Laminar shear stress promotes mitochondrial homeostasis in endothelial cells.

PubMed

Wu, Li-Hong; Chang, Hao-Chun; Ting, Pei-Ching; Wang, Danny L

2018-06-01

Vascular endothelial cells (ECs) are constantly subjected to flow-induced shear stress that is crucial for endothelial functions. Laminar shear stress (LSS) exerts atheroprotection to ECs. Mitochondrial homeostasis is essential for cellular survival. However, the effects of LSS on mitochondrial homeostasis in ECs remain unclear. Mitochondrial homeostasis in ECs exposed to LSS was examined. Cultured human umbilical vein ECs were subjected to LSS (12 dynes/cm 2 ) generated by a parallel-plate flow chamber system. ECs subjected to LSS demonstrated an increment of mitochondria in tubular form coupled with the increase of fusion proteins (Mfn2, OPA1) and the decrease of fission protein (Fis1). An increase of both long- and short- OPA1 along with a higher protease YME1L level were observed. LSS triggered a rapid phosphorylation on S637 but a decrease on S616 of fission-controlled protein Drp1. Consistently, Drp1 translocation to mitochondria was decreased in sheared ECs, suggesting that LSS promotes mitochondrial fusion. Enhanced mitochondrial biogenesis in sheared ECs was shown by the increase of mitochondrial mass and its regulatory proeins (PGC1α, TFAM, Nrf1). LSS enhances the expression of mitochondrial antioxidant enzymes and improves mitochondrial functions indicated by the increase of mitochondrial membrane potential (ΔΨm) and ATP generation. TNFα treatment decreased mitochondrial tubular network and its functions in ECs. LSS mitigated TNFα-induced mitochondrial impairments in ECs. Our results clearly indicate that LSS promotes mitochondrial homeostasis and attenuates inflammation-induced mitochondrial impairments in ECs. Our results provide novel insights into the manner of mitochondrial dynamics and functions modulated by LSS that contribute to endothelial integrity. © 2017 Wiley Periodicals, Inc.

Role of mitochondrial calcium uptake homeostasis in resting state fMRI brain networks.

PubMed

Kannurpatti, Sridhar S; Sanganahalli, Basavaraju G; Herman, Peter; Hyder, Fahmeed

2015-11-01

Mitochondrial Ca(2+) uptake influences both brain energy metabolism and neural signaling. Given that brain mitochondrial organelles are distributed in relation to vascular density, which varies considerably across brain regions, we hypothesized different physiological impacts of mitochondrial Ca(2+) uptake across brain regions. We tested the hypothesis by monitoring brain "intrinsic activity" derived from the resting state functional MRI (fMRI) blood oxygen level dependent (BOLD) fluctuations in different functional networks spanning the somatosensory cortex, caudate putamen, hippocampus and thalamus, in normal and perturbed mitochondrial Ca(2+) uptake states. In anesthetized rats at 11.7 T, mitochondrial Ca(2+) uptake was inhibited or enhanced respectively by treatments with Ru360 or kaempferol. Surprisingly, mitochondrial Ca(2+) uptake inhibition by Ru360 and enhancement by kaempferol led to similar dose-dependent decreases in brain-wide intrinsic activities in both the frequency domain (spectral amplitude) and temporal domain (resting state functional connectivity; RSFC). The fact that there were similar dose-dependent decreases in the frequency and temporal domains of the resting state fMRI-BOLD fluctuations during mitochondrial Ca(2+) uptake inhibition or enhancement indicated that mitochondrial Ca(2+) uptake and its homeostasis may strongly influence the brain's functional organization at rest. Interestingly, the resting state fMRI-derived intrinsic activities in the caudate putamen and thalamic regions saturated much faster with increasing dosage of either drug treatment than the drug-induced trends observed in cortical and hippocampal regions. Regional differences in how the spectral amplitude and RSFC changed with treatment indicate distinct mitochondrion-mediated spontaneous neuronal activity coupling within the various RSFC networks determined by resting state fMRI. Copyright © 2015 John Wiley & Sons, Ltd.

Monoamine Oxidase B Prompts Mitochondrial and Cardiac Dysfunction in Pressure Overloaded Hearts

PubMed Central

Kaludercic, Nina; Carpi, Andrea; Nagayama, Takahiro; Sivakumaran, Vidhya; Zhu, Guangshuo; Lai, Edwin W.; Bedja, Djahida; De Mario, Agnese; Chen, Kevin; Gabrielson, Kathleen L.; Lindsey, Merry L.; Pacak, Karel; Takimoto, Eiki; Shih, Jean C.; Kass, David A.; Di Lisa, Fabio

2014-01-01

Abstract Aims: Monoamine oxidases (MAOs) are mitochondrial flavoenzymes responsible for neurotransmitter and biogenic amines catabolism. MAO-A contributes to heart failure progression via enhanced norepinephrine catabolism and oxidative stress. The potential pathogenetic role of the isoenzyme MAO-B in cardiac diseases is currently unknown. Moreover, it is has not been determined yet whether MAO activation can directly affect mitochondrial function. Results: In wild type mice, pressure overload induced by transverse aortic constriction (TAC) resulted in enhanced dopamine catabolism, left ventricular (LV) remodeling, and dysfunction. Conversely, mice lacking MAO-B (MAO-B−/−) subjected to TAC maintained concentric hypertrophy accompanied by extracellular signal regulated kinase (ERK)1/2 activation, and preserved LV function, both at early (3 weeks) and late stages (9 weeks). Enhanced MAO activation triggered oxidative stress, and dropped mitochondrial membrane potential in the presence of ATP synthase inhibitor oligomycin both in neonatal and adult cardiomyocytes. The MAO-B inhibitor pargyline completely offset this change, suggesting that MAO activation induces a latent mitochondrial dysfunction, causing these organelles to hydrolyze ATP. Moreover, MAO-dependent aldehyde formation due to inhibition of aldehyde dehydrogenase 2 activity also contributed to alter mitochondrial bioenergetics. Innovation: Our study unravels a novel role for MAO-B in the pathogenesis of heart failure, showing that both MAO-driven reactive oxygen species production and impaired aldehyde metabolism affect mitochondrial function. Conclusion: Under conditions of chronic hemodynamic stress, enhanced MAO-B activity is a major determinant of cardiac structural and functional disarrangement. Both increased oxidative stress and the accumulation of aldehyde intermediates are likely liable for these adverse morphological and mechanical changes by directly targeting mitochondria. Antioxid. Redox Signal. 20, 267–280. PMID:23581564

Mitochondrion-Derived Reactive Oxygen Species Lead to Enhanced Amyloid Beta Formation

PubMed Central

Schütt, Tanja; Kurz, Christopher; Eckert, Schamim H.; Schiller, Carola; Occhipinti, Angelo; Mai, Sören; Jendrach, Marina; Eckert, Gunter P.; Kruse, Shane E.; Palmiter, Richard D.; Brandt, Ulrich; Dröse, Stephan; Wittig, Ilka; Willem, Michael; Haass, Christian; Reichert, Andreas S.; Müller, Walter E.

2012-01-01

Abstract Aims: Intracellular amyloid beta (Aβ) oligomers and extracellular Aβ plaques are key players in the progression of sporadic Alzheimer's disease (AD). Still, the molecular signals triggering Aβ production are largely unclear. We asked whether mitochondrion-derived reactive oxygen species (ROS) are sufficient to increase Aβ generation and thereby initiate a vicious cycle further impairing mitochondrial function. Results: Complex I and III dysfunction was induced in a cell model using the respiratory inhibitors rotenone and antimycin, resulting in mitochondrial dysfunction and enhanced ROS levels. Both treatments lead to elevated levels of Aβ. Presence of an antioxidant rescued mitochondrial function and reduced formation of Aβ, demonstrating that the observed effects depended on ROS. Conversely, cells overproducing Aβ showed impairment of mitochondrial function such as comprised mitochondrial respiration, strongly altered morphology, and reduced intracellular mobility of mitochondria. Again, the capability of these cells to generate Aβ was partly reduced by an antioxidant, indicating that Aβ formation was also ROS dependent. Moreover, mice with a genetic defect in complex I, or AD mice treated with a complex I inhibitor, showed enhanced Aβ levels in vivo. Innovation: We show for the first time that mitochondrion-derived ROS are sufficient to trigger Aβ production in vitro and in vivo. Conclusion: Several lines of evidence show that mitochondrion-derived ROS result in enhanced amyloidogenic amyloid precursor protein processing, and that Aβ itself leads to mitochondrial dysfunction and increased ROS levels. We propose that starting from mitochondrial dysfunction a vicious cycle is triggered that contributes to the pathogenesis of sporadic AD. Antioxid. Redox Signal. 16, 1421–1433. PMID:22229260

The metabolic enhancer piracetam ameliorates the impairment of mitochondrial function and neurite outgrowth induced by beta-amyloid peptide.

PubMed

Kurz, C; Ungerer, I; Lipka, U; Kirr, S; Schütt, T; Eckert, A; Leuner, K; Müller, W E

2010-05-01

beta-Amyloid peptide (Abeta) is implicated in the pathogenesis of Alzheimer's disease by initiating a cascade of events from mitochondrial dysfunction to neuronal death. The metabolic enhancer piracetam has been shown to improve mitochondrial dysfunction following brain aging and experimentally induced oxidative stress. We used cell lines (PC12 and HEK cells) and murine dissociated brain cells. The protective effects of piracetam in vitro and ex vivo on Abeta-induced impairment of mitochondrial function (as mitochondrial membrane potential and ATP production), on secretion of soluble Abeta and on neurite outgrowth in PC12 cells were investigated. Piracetam improves mitochondrial function of PC12 cells and acutely dissociated brain cells from young NMRI mice following exposure to extracellular Abeta(1-42). Similar protective effects against Abeta(1-42) were observed in dissociated brain cells from aged NMRI mice, or mice transgenic for mutant human amyloid precursor protein (APP) treated with piracetam for 14 days. Soluble Abeta load was markedly diminished in the brain of those animals after treatment with piracetam. Abeta production by HEK cells stably transfected with mutant human APP was elevated by oxidative stress and this was reduced by piracetam. Impairment of neuritogenesis is an important consequence of Abeta-induced mitochondrial dysfunction and Abeta-induced reduction of neurite growth in PC12 cells was substantially improved by piracetam. Our findings strongly support the concept of improving mitochondrial function as an approach to ameliorate the detrimental effects of Abeta on brain function.

Cyclin D1 Determines Mitochondrial Function In Vivo†

PubMed Central

Sakamaki, Toshiyuki; Casimiro, Mathew C.; Ju, Xiaoming; Quong, Andrew A.; Katiyar, Sanjay; Liu, Manran; Jiao, Xuanmao; Li, Anping; Zhang, Xueping; Lu, Yinan; Wang, Chenguang; Byers, Stephen; Nicholson, Robert; Link, Todd; Shemluck, Melvin; Yang, Jianguo; Fricke, Stanley T.; Novikoff, Phyllis M.; Papanikolaou, Alexandros; Arnold, Andrew; Albanese, Christopher; Pestell, Richard

2006-01-01

The cyclin D1 gene encodes a regulatory subunit of the holoenzyme that phosphorylates and inactivates the pRb tumor suppressor to promote nuclear DNA synthesis. cyclin D1 is overexpressed in human breast cancers and is sufficient for the development of murine mammary tumors. Herein, cyclin D1 is shown to perform a novel function, inhibiting mitochondrial function and size. Mitochondrial activity was enhanced by genetic deletion or antisense or small interfering RNA to cyclin D1. Global gene expression profiling and functional analysis of mammary epithelial cell-targeted cyclin D1 antisense transgenics demonstrated that cyclin D1 inhibits mitochondrial activity and aerobic glycolysis in vivo. Reciprocal regulation of these genes was observed in cyclin D1-induced mammary tumors. Cyclin D1 thus integrates nuclear DNA synthesis and mitochondrial function. PMID:16809779

Stomatin-Like Protein 2 Binds Cardiolipin and Regulates Mitochondrial Biogenesis and Function▿

PubMed Central

Christie, Darah A.; Lemke, Caitlin D.; Elias, Isaac M.; Chau, Luan A.; Kirchhof, Mark G.; Li, Bo; Ball, Eric H.; Dunn, Stanley D.; Hatch, Grant M.; Madrenas, Joaquín

2011-01-01

Stomatin-like protein 2 (SLP-2) is a widely expressed mitochondrial inner membrane protein of unknown function. Here we show that human SLP-2 interacts with prohibitin-1 and -2 and binds to the mitochondrial membrane phospholipid cardiolipin. Upregulation of SLP-2 expression increases cardiolipin content and the formation of metabolically active mitochondrial membranes and induces mitochondrial biogenesis. In human T lymphocytes, these events correlate with increased complex I and II activities, increased intracellular ATP stores, and increased resistance to apoptosis through the intrinsic pathway, ultimately enhancing cellular responses. We propose that the function of SLP-2 is to recruit prohibitins to cardiolipin to form cardiolipin-enriched microdomains in which electron transport complexes are optimally assembled. Likely through the prohibitin functional interactome, SLP-2 then regulates mitochondrial biogenesis and function. PMID:21746876

Role of Parkin and endurance training on mitochondrial turnover in skeletal muscle.

PubMed

Chen, Chris Chin Wah; Erlich, Avigail T; Hood, David A

2018-03-17

Parkin is a ubiquitin ligase that is involved in the selective removal of dysfunctional mitochondria. This process is termed mitophagy and can assist in mitochondrial quality control. Endurance training can produce adaptations in skeletal muscle toward a more oxidative phenotype, an outcome of enhanced mitochondrial biogenesis. It remains unknown whether Parkin-mediated mitophagy is involved in training-induced increases in mitochondrial content and function. Our purpose was to determine a role for Parkin in maintaining mitochondrial turnover in muscle, and its requirement in mediating mitochondrial biogenesis following endurance exercise training. Wild-type and Parkin knockout (KO) mice were trained for 6 weeks and then treated with colchicine or vehicle to evaluate the role of Parkin in mediating changes in mitochondrial content, function and acute exercise-induced mitophagy flux. Our results indicate that Parkin is required for the basal maintenance of mitochondrial function. The absence of Parkin did not significantly alter mitophagy basally; however, acute exercise produced an elevation in mitophagy flux, a response that was Parkin-dependent. Mitochondrial content was increased following training in both genotypes, but this occurred without an induction of PGC-1α signaling in KO animals. Interestingly, the increased muscle mitochondrial content in response to training did not influence basal mitophagy flux, despite an enhanced expression and localization of Parkin to mitochondria in WT animals. Furthermore, exercise-induced mitophagy flux was attenuated with training in WT animals, suggesting a lower rate of mitochondrial degradation resulting from improved organelle quality with training. In contrast, training led to a higher mitochondrial content, but with persistent dysfunction, in KO animals. Thus, the lack of a rescue of mitochondrial dysfunction with training in the absence of Parkin is the likely reason for the impaired training-induced attenuation of mitophagy flux compared to WT animals. Our study demonstrates that Parkin is required for exercise-induced mitophagy flux. Exercise-induced mitophagy is reduced with training in muscle, likely due to attenuated signaling consequent to increased mitochondrial content and quality. Our data suggest that Parkin is essential for the maintenance of basal mitochondrial function, as well as for the accumulation of normally functioning mitochondria as a result of training adaptations in muscle.

Metformin reduces hyper-reactivity of platelets from patients with polycystic ovary syndrome by improving mitochondrial integrity.

PubMed

Randriamboavonjy, Voahanginirina; Mann, W Alexander; Elgheznawy, Amro; Popp, Rüdiger; Rogowski, Paul; Dornauf, Imke; Dröse, Stefan; Fleming, Ingrid

2015-08-31

Polycystic ovary syndrome (PCOS) is associated with decreased fertility, insulin resistance and an increased risk of developing cardiovascular disease. Treating PCOS patients with metformin improves fertility and decreases cardiovascular complications. Given that platelet activation contributes to both infertility and cardiovascular disease development, we assessed platelet reactivity in PCOS patients and the consequences of metformin treatment. Compared to washed platelets from healthy donors, platelets from PCOS patients demonstrated enhanced reactivity and impaired activation of the AMP-activated kinase (AMPK). PCOS platelets also demonstrated enhanced expression of mitochondrial proteins such as the cytochrome c reductase, ATP synthase and the voltage-dependent anion channel-1. However, mitochondrial function was impaired as demonstrated by a decreased respiration rate. In parallel, the phosphorylation of dynamin-related protein-1 (Drp-1) on Ser616 was increased while that on Ser637 decreased. The latter changes were accompanied by decreased mitochondrial size. In insulin-resistant PCOS patients (HOMA-IR> 2) metformin treatment (1.7 g per day for 4 weeks to 6 months) improved insulin sensitivity, restored mitochondrial integrity and function and normalised platelet aggregation. Treatment was without effect in PCOS patients with HOMA-IR< 2. Moreover, treatment of megakaryocytes with metformin enhanced mitochondrial content and in the same cells metformin enhanced the phosphorylation of the Drp-1 on Ser637 via an AMPKα1-dependent mechanism. In conclusion, the improvement of mitochondrial integrity and platelet reactivity may contribute to the beneficial effects of metformin on cardiovascular disease.

Mitochondrial pharmacology: electron transport chain bypass as strategies to treat mitochondrial dysfunction.

PubMed

Atamna, Hani; Mackey, Jeanette; Dhahbi, Joseph M

2012-01-01

Mitochondrial dysfunction (primary or secondary) is detrimental to intermediary metabolism. Therapeutic strategies to treat/prevent mitochondrial dysfunction could be valuable for managing metabolic and age-related disorders. Here, we review strategies proposed to treat mitochondrial impairment. We then concentrate on redox-active agents, with mild-redox potential, who shuttle electrons among specific cytosolic or mitochondrial redox-centers. We propose that specific redox agents with mild redox potential (-0.1 V; 0.1 V) improve mitochondrial function because they can readily donate or accept electrons in biological systems, thus they enhance metabolic activity and prevent reactive oxygen species (ROS) production. These agents are likely to lack toxic effects because they lack the risk of inhibiting electron transfer in redox centers. This is different from redox agents with strong negative (-0.4 V; -0.2 V) or positive (0.2 V; 0.4 V) redox potentials who alter the redox status of redox-centers (i.e., become permanently reduced or oxidized). This view has been demonstrated by testing the effect of several redox active agents on cellular senescence. Methylene blue (MB, redox potential ≅10 mV) appears to readily cycle between the oxidized and reduced forms using specific mitochondrial and cytosolic redox centers. MB is most effective in delaying cell senescence and enhancing mitochondrial function in vivo and in vitro. Mild-redox agents can alter the biochemical activity of specific mitochondrial components, which then in response alters the expression of nuclear and mitochondrial genes. We present the concept of mitochondrial electron-carrier bypass as a potential result of mild-redox agents, a method to prevent ROS production, improve mitochondrial function, and delay cellular aging. Thus, mild-redox agents may prevent/delay mitochondria-driven disorders. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Developmental plasticity of mitochondrial function in American alligators, Alligator mississippiensis

PubMed Central

Crossley, Janna; Elsey, Ruth M.; Dzialowski, Edward M.; Shiels, Holly A.; Crossley, Dane A.

2016-01-01

The effect of hypoxia on cellular metabolism is well documented in adult vertebrates, but information is entirely lacking for embryonic organisms. The effect of hypoxia on embryonic physiology is particularly interesting, as metabolic responses during development may have life-long consequences, due to developmental plasticity. To this end, we investigated the effects of chronic developmental hypoxia on cardiac mitochondrial function in embryonic and juvenile American alligators (Alligator mississippiensis). Alligator eggs were incubated in 21% or 10% oxygen from 20 to 90% of embryonic development. Embryos were either harvested at 90% development or allowed to hatch and then reared in 21% oxygen for 3 yr. Ventricular mitochondria were isolated from embryonic/juvenile alligator hearts. Mitochondrial respiration and enzymatic activities of electron transport chain complexes were measured with a microrespirometer and spectrophotometer, respectively. Developmental hypoxia induced growth restriction and increased relative heart mass, and this phenotype persisted into juvenile life. Embryonic mitochondrial function was not affected by developmental hypoxia, but at the juvenile life stage, animals from hypoxic incubations had lower levels of Leak respiration and higher respiratory control ratios, which is indicative of enhanced mitochondrial efficiency. Our results suggest developmental hypoxia can have life-long consequences for alligator morphology and metabolic function. Further investigations are necessary to reveal the adaptive significance of the enhanced mitochondrial efficiency in the hypoxic phenotype. PMID:27707718

Modulating molecular chaperones improves sensory fiber recovery and mitochondrial function in diabetic peripheral neuropathy

PubMed Central

Urban, Michael J.; Pan, Pan; Farmer, Kevin L.; Zhao, Huiping; Blagg, Brian S.J.; Dobrowsky, Rick T.

2012-01-01

Quantification of intra-epidermal nerve fibers (iENFs) is an important approach to stage diabetic peripheral neuropathy (DPN) and is a promising clinical endpoint for identifying beneficial therapeutics. Mechanistically, diabetes decreases neuronal mitochondrial function and enhancing mitochondrial respiratory capacity may aid neuronal recovery from glucotoxic insults. We have proposed that modulating the activity and expression of heat shock proteins (Hsp) may be of benefit in treating DPN. KU-32 is a C-terminal Hsp90 inhibitor that improved thermal hypoalgesia in diabetic C57Bl/6 mice but it was not determined if this was associated with an increase in iENF density and mitochondrial function. After 16 weeks of diabetes, Swiss Webster mice showed decreased electrophysiological and psychosensory responses and a >30% loss of iENFs. Treatment of the mice with ten weekly doses of 20 mg/kg KU-32 significantly reversed pre-existing deficits in nerve conduction velocity and responses to mechanical and thermal stimuli. KU-32 therapy significantly reversed the pre-existing loss of iENFs despite the identification of a sub-group of drug-treated diabetic mice that showed improved thermal sensitivity but no increase in iENF density. To determine if the improved clinical indices correlated with enhanced mitochondrial activity, sensory neurons were isolated and mitochondrial bioenergetics assessed ex vivo using extracellular flux technology. Diabetes decreased maximal respiratory capacity in sensory neurons and this deficit was improved following KU-32 treatment. In conclusion, KU-32 improved physiological and morphologic markers of degenerative neuropathy and drug efficacy may be related to enhanced mitochondrial bioenergetics in sensory neurons. PMID:22465570

Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

NASA Astrophysics Data System (ADS)

Yoon, Ok Ja; Lee, Hyun Jung; Jang, Yeong Mi; Kim, Hyun Woo; Lee, Won Bok; Kim, Sung Su; Lee, Nae-Eung

2011-08-01

The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

Temporal manipulation of mitochondrial function by virulent Francisella tularensis to limit inflammation and control cell death.

PubMed

Jessop, Forrest; Schwarz, Benjamin; Heitmann, Emily; Buntyn, Robert; Wehrly, Tara; Bosio, Catharine M

2018-05-14

Francisella tularensis ssp tularensis (Ftt) is a highly pathogenic intracellular bacterium that suppresses host inflammation by impairing the metabolic shift from oxidative phosphorylation to glycolysis. Decreased mitochondrial metabolism is central to initiating a metabolic shift to glycolysis and regulating inflammation, but Ftt manipulation of host mitochondrial function has not been explored. We demonstrate using extracellular flux analysis that Ftt infection initially improves host macrophage mitochondrial bioenergetics in a capsule dependent manner. Enhancement of mitochondrial function by Ftt allowed for modest replication and inhibition of apoptosis early after infection. However, using live cell imaging we found that Ftt facilitated the loss of mitochondrial function at later time points during infection in a capsule independent fashion. This loss of function was paired with oncosis and rapid bacterial replication. Inhibition of oncosis reduced intracellular bacteria numbers, underscoring the requirement for this process during Ftt infection. These findings establish that temporal mitochondrial manipulation by Ftt is critical for maintenance of a non-inflammatory environment and subsequently aids in optimal replication and dissemination of this pathogenic organism. Copyright © 2018 American Society for Microbiology.

TAT-MTS-MCM fusion proteins reduce MMA levels and improve mitochondrial activity and liver function in MCM-deficient cells.

PubMed

Erlich-Hadad, Tal; Hadad, Rita; Feldman, Anat; Greif, Hagar; Lictenstein, Michal; Lorberboum-Galski, Haya

2018-03-01

Methylmalonic aciduria (MMA) is a disorder of organic acid metabolism resulting from a functional defect of the mitochondrial enzyme, methylmalonyl-CoA mutase (MCM). The main treatments for MMA patients are dietary restriction of propiogenic amino acids and carnitine supplementation. Liver or combined liver/kidney transplantation has been used to treat those with the most severe clinical manifestations. Thus, therapies are necessary to help improve quality of life and prevent liver, renal and neurological complications. Previously, we successfully used the TAT-MTS-Protein approach for replacing a number of mitochondrial-mutated proteins. In this targeted system, TAT, an 11 a.a peptide, which rapidly and efficiently can cross biological membranes, is fused to a mitochondrial targeting sequence (MTS), followed by the mitochondrial mature protein which sends the protein into the mitochondria. In the mitochondria, the TAT-MTS is cleaved off and the native protein integrates into its natural complexes and is fully functional. In this study, we used heterologous MTSs of human, nuclear-encoded mitochondrial proteins, to target the human MCM protein into the mitochondria. All fusion proteins reached the mitochondria and successfully underwent processing. Treatment of MMA patient fibroblasts with these fusion proteins restored mitochondrial activity such as ATP production, mitochondrial membrane potential and oxygen consumption, indicating the importance of mitochondrial function in this disease. Treatment with the fusion proteins enhanced cell viability and most importantly reduced MMA levels. Treatment also enhanced albumin and urea secretion in a CRISPR/Cas9-engineered HepG2 MUT (-/-) liver cell line. Therefore, we suggest using this TAT-MTS-Protein approach for the treatment of MMA. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Structural Modification of (-)-Epigallocatechin Gallate (EGCG) Shows Significant Enhancement in Mitochondrial Biogenesis.

PubMed

Ha, Taewoong; Kim, Mi Kyoung; Park, Kwang-Su; Jung, Woong; Choo, Hyunah; Chong, Youhoon

2018-04-18

(-)-Epigallocatechin-3-gallate (EGCG) is known as a mitochondria-targeted molecule that can prevent mitochondrial deterioration and induce mitochondrial biogenesis by modulating key regulators of mitochondrial metabolism. In this study, we tackled whether derivatization of EGCG could result in enhancement of its effects on mitochondrial biogenesis. EGCG, EGCG peracetate (AcEGCG), and its 4″- O-alkyl substituted congeners prepared by previously reported procedures were biologically evaluated. Interestingly, EGCG and AcEGCG were only marginally effective in inducing mitochondrial biogenesis, while AcEGCG congeners with an alkyl group at the 4″- O position showed significantly increased biological activity compared to their parent compound. Among these series, 3f with a methyl-branched carbonate chain at the 4″- O position of the AcEGCG scaffold showed the most enhancement in inducing mitochondrial biogenesis. Hepa1-6 cells treated with 3f exhibited increases in both mitochondrial mass (1.5 times) and relative mtDNA content to nDNA (1.5 times). As a mitochondrial biogenesis enhancer, 3f also increased expression levels of regulators for mitochondrial function, including PGC-1α (4.0 fold), p-AMPK (2.5 fold), SIRT1 (4.2 fold), ERRα (1.8 fold), NRF-1 (1.6 fold), NRF-2 (1.7 fold), and mtTFA (1.6 folds). Investigation of oxidative phosphorylation by mitochondria in the presence of 3f revealed that 3f increased the NAD + /NADH ratio, the amount of cytochrome c, ATP synthesis, and oxygen consumption in Hepa1-6 cells by 2.2, 1.4, 1.5, and 2.1 fold, respectively. Taken together, these results warrant an extensive structure-activity relationship study for EGCG derivatives to develop novel mitochondrial biogenesis enhancers.

Expression of mitochondrial regulatory genes parallels respiratory capacity and contractile function in a rat model of hypoxia-induced right ventricular hypertrophy

USDA-ARS?s Scientific Manuscript database

Chronic hypobaric hypoxia (CHH) increases load on the right ventricle (RV) resulting in RV hypertrophy. We hypothesized that CHH elicits distinct responses, i.e., the hypertrophied RV, unlike the left ventricle (LV), displaying enhanced mitochondrial respiratory and contractile function. Wistar rats...

Brain mitochondrial bioenergetics change with rapid and prolonged shifts in aggression in the honey bee, Apis mellifera.

PubMed

Rittschof, Clare C; Vekaria, Hemendra J; Palmer, Joseph H; Sullivan, Patrick G

2018-04-25

Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury. Furthermore, in the honey bee, age-related increases in aggressive tendency are associated with increased baseline brain mitochondrial respiration, as well as increased plasticity in response to metabolic fuel type in vitro Similarly, diet restriction and ketone body feeding, which commonly enhance mammalian brain mitochondrial function in vivo , cause increased aggression. Thus, even in normal behavioral contexts, brain mitochondria show a surprising degree of variation in function over both rapid and prolonged time scales, with age predicting both baseline function and plasticity in function. These results suggest that mitochondrial function is integral to modulating aggression-related neuronal signaling. We hypothesize that variation in function reflects mitochondrial calcium buffering activity, and that shifts in mitochondrial function signal to the neuronal soma to regulate gene expression and neural energetic state. Modulating brain energetic state is emerging as a critical component of the regulation of behavior in non-diseased contexts. © 2018. Published by The Company of Biologists Ltd.

Combined effects of cadmium, temperature and hypoxia-reoxygenation on mitochondrial function in rainbow trout (Oncorhynchus mykiss).

PubMed

Onukwufor, John O; Stevens, Don; Kamunde, Collins

2017-01-01

Although aquatic organisms face multiple environmental stressors that may interact to alter adverse outcomes, our knowledge of stressor-stressor interaction on cellular function is limited. We investigated the combined effects of cadmium (Cd), hypoxia-reoxygenation (H-R) and temperature on mitochondrial function. Liver mitochondria from juvenile rainbow trout were exposed to Cd (0-20μM) and H-R (0 and 5min) at 5, 13 and 25°C followed by measurements of mitochondrial Cd load, volume, complex І active (A)↔deactive (D) transition, membrane potential, ROS release and ultrastructural changes. At high temperature Cd exacerbated H-R-imposed reduction of maximal complex I (CI) respiration whereas at low temperature 5 and 10μM stimulated maximal CI respiration post H-R. The basal respiration showed a biphasic response at high temperatures with low Cd concentrations reducing the stimulatory effect of H-R and high concentrations enhancing this effect. At low temperature Cd monotonically enhanced H-R-induced stimulation of basal respiration. Cd and H-R reduced both the P/O ratio and the RCR at all 3 temperatures. Temperature rise alone increased mitochondrial Cd load and toxicity, but combined H-R and temperature exposure reduced mitochondrial Cd load but surprisingly exacerbated the mitochondrial dysfunction. Mitochondrial dysfunction induced by H-R was associated with swelling of the organelle and blocking of conversion of CІ D to A form. However, low amounts of Cd protected against H-R induced swelling and prevented the inhibition of H-R-induced CI D to A transition. Both H-R and Cd dissipated mitochondrial membrane potential Δψ m and damaged mitochondrial structure. We observed increased reactive oxygen species (H 2 O 2 ) release that together with the protection afforded by EGTA, vitamin E and N-acetylcysteine against the Δψ m dissipation suggested direct involvement of Cd and oxidative stress. Overall, our findings indicate that mitochondrial sensitivity to Cd toxicity was enhanced by the effects of H-R and temperature, and changes in mitochondrial Cd load did not always explain this effect. Copyright © 2016 Elsevier B.V. All rights reserved.

Monomeric cocoa catechins enhance β-cell function by increasing mitochondrial respiration.

PubMed

Rowley, Thomas J; Bitner, Benjamin F; Ray, Jason D; Lathen, Daniel R; Smithson, Andrew T; Dallon, Blake W; Plowman, Chase J; Bikman, Benjamin T; Hansen, Jason M; Dorenkott, Melanie R; Goodrich, Katheryn M; Ye, Liyun; O'Keefe, Sean F; Neilson, Andrew P; Tessem, Jeffery S

2017-11-01

A hallmark of type 2 diabetes (T2D) is β-cell dysfunction and the eventual loss of functional β-cell mass. Therefore, mechanisms that improve or preserve β-cell function could be used to improve the quality of life of individuals with T2D. Studies have shown that monomeric, oligomeric and polymeric cocoa flavanols have different effects on obesity, insulin resistance and glucose tolerance. We hypothesized that these cocoa flavanols may have beneficial effects on β-cell function. INS-1 832/13-derived β-cells and primary rat islets cultured with a monomeric catechin-rich cocoa flavanol fraction demonstrated enhanced glucose-stimulated insulin secretion, while cells cultured with total cocoa extract and with oligomeric or polymeric procyanidin-rich fraction demonstrated no improvement. The increased glucose-stimulated insulin secretion in the presence of the monomeric catechin-rich fraction corresponded with enhanced mitochondrial respiration, suggesting improvements in β-cell fuel utilization. Mitochondrial complex III, IV and V components are up-regulated after culture with the monomer-rich fraction, corresponding with increased cellular ATP production. The monomer-rich fraction improved cellular redox state and increased glutathione concentration, which corresponds with nuclear factor, erythroid 2 like 2 (Nrf2) nuclear localization and expression of Nrf2 target genes including nuclear respiratory factor 1 (Nrf1) and GA binding protein transcription factor alpha subunit (GABPA), essential genes for increasing mitochondrial function. We propose a model by which monomeric cocoa catechins improve the cellular redox state, resulting in Nrf2 nuclear migration and up-regulation of genes critical for mitochondrial respiration, glucose-stimulated insulin secretion and ultimately improved β-cell function. These results suggest a mechanism by which monomeric cocoa catechins exert their effects as an effective complementary strategy to benefit T2D patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Exercise and nutritional interventions for improving aging muscle health.

PubMed

Forbes, Scott C; Little, Jonathan P; Candow, Darren G

2012-08-01

Skeletal muscle mass declines with age (i.e., sarcopenia) resulting in muscle weakness and functional limitations. Sarcopenia has been associated with physiological changes in muscle morphology, protein and hormonal kinetics, insulin resistance, inflammation, and oxidative stress. The purpose of this review is to highlight how exercise and nutritional intervention strategies may benefit aging muscle. It is well known that resistance exercise training increases muscle strength and size and evidence also suggests that resistance training can increase mitochondrial content and decrease oxidative stress in older adults. Recent findings suggest that fast-velocity resistance exercise may be an effective intervention for older adults to enhance muscle power and functional capacity. Aerobic exercise training may also benefit aging skeletal muscle by enhancing mitochondrial bioenergetics, improving insulin sensitivity, and/or decreasing oxidative stress. In addition to exercise, creatine monohydrate, milk-based proteins, and essential fatty acids all have biological effects which could enhance some of the physiological adaptations from exercise training in older adults. Additional research is needed to determine whether skeletal muscle adaptations to increased activity in older adults are further enhanced with effective nutritional interventions and whether this is due to enhanced muscle protein synthesis, improved mitochondrial function, and/or a reduced inflammatory response.

Thyrotropin-releasing hormone controls mitochondrial biology in human epidermis.

PubMed

Knuever, Jana; Poeggeler, Burkhard; Gáspár, Erzsébet; Klinger, Matthias; Hellwig-Burgel, Thomas; Hardenbicker, Celine; Tóth, Balázs I; Bíró, Tamás; Paus, Ralf

2012-03-01

Mitochondrial capacity and metabolic potential are under the control of hormones, such as thyroid hormones. The most proximal regulator of the hypothalamic-pituitary-thyroid (HPT) axis, TRH, is the key hypothalamic integrator of energy metabolism via its impact on thyroid hormone secretion. Here, we asked whether TRH directly modulates mitochondrial functions in normal, TRH-receptor-positive human epidermis. Organ-cultured human skin was treated with TRH (5-100 ng/ml) for 12-48 h. TRH significantly increased epidermal immunoreactivity for the mitochondria-selective subunit I of respiratory chain complex IV (MTCO1). This resulted from an increased MTCO1 transcription and protein synthesis and a stimulation of mitochondrial biogenesis as demonstrated by transmission electron microscopy and TRH-enhanced mitochondrial DNA synthesis. TRH also significantly stimulated the transcription of several other mitochondrial key genes (TFAM, HSP60, and BMAL1), including the master regulator of mitochondrial biogenesis (PGC-1α). TRH significantly enhanced mitochondrial complex I and IV enzyme activity and enhanced the oxygen consumption of human skin samples, which shows that the stimulated mitochondria are fully vital because the main source for cellular oxygen consumption is mitochondrial endoxidation. These findings identify TRH as a potent, novel neuroendocrine stimulator of mitochondrial activity and biogenesis in human epidermal keratinocytes in situ. Thus, human epidermis offers an excellent model for dissecting neuroendocrine controls of human mitochondrial biology under physiologically relevant conditions and for exploring corresponding clinical applications.

Mitochondrial modulators in experimental Huntington's disease: reversal of mitochondrial dysfunctions and cognitive deficits.

PubMed

Mehrotra, Arpit; Kanwal, Abhinav; Banerjee, Sanjay Kumar; Sandhir, Rajat

2015-06-01

Huntington's disease (HD) is a chronic neurodegenerative condition involving impaired mitochondrial functions. The present study evaluates the therapeutic potential of combined administration of mitochondrial modulators: alpha-lipoic acid and acetyl-l-carnitine on mitochondrial dysfunctions in 3-NP-induced HD. Our results reveal 3-NP administration resulted in compromise of mitochondrial functions in terms of: (1) impaired activity of mitochondrial respiratory chain enzymes, altered cytochrome levels, reduced histochemical staining of complex-II and IV, reduced in-gel activity of complex-I to V, and reduced mRNA expression of respiratory chain complexes; (2) enhanced mitochondrial oxidative stress indicated by increased malondialdehyde, protein carbonyls, reactive oxygen species and nitrite levels, along with decreased Mn-superoxide dismutase and catalase activity; (3) mitochondrial structural changes measured by mitochondrial swelling, reduced mitochondrial membrane potential and ultra-structure changes; (4) increased cytosolic cytochrome c levels, caspase-3 and -9 activity along with altered expression of apoptotic proteins (AIF, Bim, Bad, and Bax); and (5) impaired cognitive functions assessed using Morris water maze and Y-maze. Combination of mitochondrial modulators (alpha-lipoic acid + acetyl-l-carnitine) on the other hand ameliorated 3-NP-induced mitochondrial dysfunctions, oxidative stress, histologic alterations, and behavioral deficits, suggesting their therapeutic efficacy in the management of HD. Copyright © 2015 Elsevier Inc. All rights reserved.

MitoQ protects dopaminergic neurons in a 6-OHDA induced PD model by enhancing Mfn2-dependent mitochondrial fusion via activation of PGC-1α.

PubMed

Xi, Ye; Feng, Dayun; Tao, Kai; Wang, Ronglin; Shi, Yajun; Qin, Huaizhou; Murphy, Michael P; Yang, Qian; Zhao, Gang

2018-05-26

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra compacta (SNc). Although mitochondrial dysfunction is the critical factor in the pathogenesis of PD, the underlying molecular mechanisms are not well understood, and as a result, effective medical interventions are lacking. Mitochondrial fission and fusion play important roles in the maintenance of mitochondrial function and cell viability. Here, we investigated the effects of MitoQ, a mitochondria-targeted antioxidant, in 6-hydroxydopamine (6-OHDA)-induced in vitro and in vivo PD models. We observed that 6-OHDA enhanced mitochondrial fission by decreasing the expression of Mfn1, Mfn2 and OPA1 as well as by increasing the expression of Drp1 in the dopaminergic (DA) cell line SN4741. Notably, MitoQ treatment particularly upregulated the Mfn2 protein and mRNA levels and promoted mitochondrial fusion in the presence of 6-OHDA in a Mfn2-dependent manner. In addition, MitoQ also stabilized mitochondrial morphology and function in the presence of 6-OHDA, which further suppressed the formation of reactive oxygen species (ROS), as well as ameliorated mitochondrial fragmentation and cellular apoptosis. Moreover, the activation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) was attributed to the upregulation of Mfn2 induced by MitoQ. Consistent with these findings, administration of MitoQ in 6-OHDA-treated mice significantly rescued the decrease of Mfn2 expression and the loss of DA neurons in the SNc. Taken together, our findings suggest that MitoQ protects DA neurons in a 6-OHDA induced PD model by activating PGC-1α to enhance Mfn2-dependent mitochondrial fusion. Copyright © 2018 Elsevier B.V. All rights reserved.

DJ-1 KNOCK-DOWN IMPAIRS ASTROCYTE MITOCHONDRIAL FUNCTION

PubMed Central

LARSEN, N. J.; AMBROSI, G.; MULLETT, S. J.; BERMAN, S. B.; HINKLE, D. A.

2012-01-01

Mitochondrial dysfunction has long been implicated in the pathogenesis of Parkinson’s disease (PD). PD brain tissues show evidence for mitochondrial respiratory chain Complex I deficiency. Pharmacological inhibitors of Complex I, such as rotenone, cause experimental parkinsonism. The cytoprotective protein DJ-1, whose deletion is sufficient to cause genetic PD, is also known to have mitochondria-stabilizing properties. We have previously shown that DJ-1 is over-expressed in PD astrocytes, and that DJ-1 deficiency impairs the capacity of astrocytes to protect co-cultured neurons against rotenone. Since DJ-1 modulated, astrocyte-mediated neuroprotection against rotenone may depend upon proper astrocytic mitochondrial functioning, we hypothesized that DJ-1 deficiency would impair astrocyte mitochondrial motility, fission/fusion dynamics, membrane potential maintenance, and respiration, both at baseline and as an enhancement of rotenone-induced mitochondrial dysfunction. In astrocyte-enriched cultures, we observed that DJ-1 knock-down reduced mitochondrial motility primarily in the cellular processes of both untreated and rotenone treated cells. In these same cultures, DJ-1 knock-down did not appreciably affect mitochondrial fission, fusion, or respiration, but did enhance rotenone-induced reductions in the mitochondrial membrane potential. In neuron–astrocyte co-cultures, astrocytic DJ-1 knock-down reduced astrocyte process mitochondrial motility in untreated cells, but this effect was not maintained in the presence of rotenone. In the same co-cultures, astrocytic DJ-1 knock-down significantly reduced mitochondrial fusion in the astrocyte cell bodies, but not the processes, under the same conditions of rotenone treatment in which DJ-1 deficiency is known to impair astrocyte-mediated neuroprotection. Our studies therefore demonstrated the following new findings: (i) DJ-1 deficiency can impair astrocyte mitochondrial physiology at multiple levels, (ii) astrocyte mitochondrial dynamics vary with sub-cellular region, and (iii) the physical presence of neurons can affect astrocyte mitochondrial behavior. PMID:21907265

Exercise training protects against aging-induced mitochondrial fragmentation in mouse skeletal muscle in a PGC-1α dependent manner.

PubMed

Halling, Jens Frey; Ringholm, Stine; Olesen, Jesper; Prats, Clara; Pilegaard, Henriette

2017-10-01

Aging is associated with impaired mitochondrial function, whereas exercise training enhances mitochondrial content and function in part through activation of PGC-1α. Mitochondria form dynamic networks regulated by fission and fusion with profound effects on mitochondrial functions, yet the effects of aging and exercise training on mitochondrial network structure remain unclear. This study examined the effects of aging and exercise training on mitochondrial network structure using confocal microscopy on mitochondria-specific stains in single muscle fibers from PGC-1α KO and WT mice. Hyperfragmentation of mitochondrial networks was observed in aged relative to young animals while exercise training normalized mitochondrial network structure in WT, but not in PGC-1α KO. Mitochondrial fission protein content (FIS1 and DRP1) relative to mitochondrial content was increased with aging in both WT and PGC-1α KO mice, while exercise training lowered mitochondrial fission protein content relative to mitochondrial content only in WT. Mitochondrial fusion protein content (MFN1/2 and OPA1) was unaffected by aging and lifelong exercise training in both PGC-1α KO and WT mice. The present results provide evidence that exercise training rescues aging-induced mitochondrial fragmentation in skeletal muscle by suppressing mitochondrial fission protein expression in a PGC-1α dependent manner. Copyright © 2017 Elsevier Inc. All rights reserved.

GPA protects the nigrostriatal dopamine system by enhancing mitochondrial function.

PubMed

Horvath, Tamas L; Erion, Derek M; Elsworth, John D; Roth, Robert H; Shulman, Gerald I; Andrews, Zane B

2011-07-01

Guanidinopropionic acid (GPA) increases AMPK activity, mitochondrial function and biogenesis in muscle and improves physiological function, for example during aging. Mitochondrial dysfunction is a major contributor to the pathogenesis of Parkinson's disease. Here we tested whether GPA prevents neurodegeneration of the nigrostriatal dopamine system in MPTP-treated mice. Mice were fed a diet of 1% GPA or normal chow for 4 weeks and then treated with either MPTP or saline. Indices of nigrostriatal function were examined by HPLC, immunohistochemistry, stereology, electron microscopy and mitochondrial respiration. MPTP intoxication decreased TH neurons in the SNpc of normal chow-fed mice; however GPA-fed mice remarkably exhibited no loss of TH neurons in the SNpc. MPTP caused a decrease in striatal dopamine of both normal chow- and GPA-fed mice, although this effect was significantly attenuated in GPA-fed mice. GPA-fed mice showed increased AMPK activity, mitochondrial respiration and mitochondrial number in nigrostriatal TH neurons, suggesting that the neuroprotective effects of GPA involved AMPK-dependent increases in mitochondrial function and biogenesis. MPTP treatment produced a decrease in mitochondrial number and volume in normal chow-fed mice but not GPA-fed mice. Our results show the neuroprotective properties of GPA in a mouse model of Parkinson's disease are partially mediated by AMPK and mitochondrial function. Mitochondrial dysfunction is a common problem in neurodegeneration and thus GPA may slow disease progression in other models of neurodegeneration. Copyright © 2011 Elsevier Inc. All rights reserved.

Mitochondrial Gene Therapy: Advances in Mitochondrial Gene Cloning, Plasmid Production, and Nanosystems Targeted to Mitochondria.

PubMed

Coutinho, Eduarda; Batista, Cátia; Sousa, Fani; Queiroz, João; Costa, Diana

2017-03-06

Mitochondrial gene therapy seems to be a valuable and promising strategy to treat mitochondrial disorders. The use of a therapeutic vector based on mitochondrial DNA, along with its affinity to the site of mitochondria, can be considered a powerful tool in the reestablishment of normal mitochondrial function. In line with this and for the first time, we successfully cloned the mitochondrial gene ND1 that was stably maintained in multicopy pCAG-GFP plasmid, which is used to transform E. coli. This mitochondrial-gene-based plasmid was encapsulated into nanoparticles. Furthermore, the functionalization of nanoparticles with polymers, such as cellulose or gelatin, enhances their overall properties and performance for gene therapy. The fluorescence arising from rhodamine nanoparticles in mitochondria and a fluorescence microscopy study show pCAG-GFP-ND1-based nanoparticles' cell internalization and mitochondria targeting. The quantification of GFP expression strongly supports this finding. This work highlights the viability of gene therapy based on mitochondrial DNA instigating further in vitro research and clinical translation.

Insulin and IGF-1 improve mitochondrial function in a PI-3K/Akt-dependent manner and reduce mitochondrial generation of reactive oxygen species in Huntington's disease knock-in striatal cells.

PubMed

Ribeiro, Márcio; Rosenstock, Tatiana R; Oliveira, Ana M; Oliveira, Catarina R; Rego, A Cristina

2014-09-01

Oxidative stress and mitochondrial dysfunction have been described in Huntington's disease, a disorder caused by expression of mutant huntingtin (mHtt). IGF-1 was previously shown to protect HD cells, whereas insulin prevented neuronal oxidative stress. In this work we analyzed the role of insulin and IGF-1 in striatal cells derived from HD knock-in mice on mitochondrial production of reactive oxygen species (ROS) and related antioxidant and signaling pathways influencing mitochondrial function. Insulin and IGF-1 decreased mitochondrial ROS induced by mHtt and normalized mitochondrial SOD activity, without affecting intracellular glutathione levels. IGF-1 and insulin promoted Akt phosphorylation without changing the nuclear levels of phosphorylated Nrf2 or Nrf2/ARE activity. Insulin and IGF-1 treatment also decreased mitochondrial Drp1 phosphorylation, suggesting reduced mitochondrial fragmentation, and ameliorated mitochondrial function in HD cells in a PI-3K/Akt-dependent manner. This was accompanied by increased total and phosphorylated Akt, Tfam, and mitochondrial-encoded cytochrome c oxidase II, as well as Tom20 and Tom40 in mitochondria of insulin- and IGF-1-treated mutant striatal cells. Concomitantly, insulin/IGF-1-treated mutant cells showed reduced apoptotic features. Hence, insulin and IGF-1 improve mitochondrial function and reduce mitochondrial ROS caused by mHtt by activating the PI-3K/Akt signaling pathway, in a process independent of Nrf2 transcriptional activity, but involving enhanced mitochondrial levels of Akt and mitochondrial-encoded complex IV subunit. Copyright © 2014 Elsevier Inc. All rights reserved.

Calcium-dependent mitochondrial cAMP production enhances aldosterone secretion.

PubMed

Katona, Dávid; Rajki, Anikó; Di Benedetto, Giulietta; Pozzan, Tullio; Spät, András

2015-09-05

Glomerulosa cells secrete aldosterone in response to agonists coupled to Ca(2+) increases such as angiotensin II and corticotrophin, coupled to a cAMP dependent pathway. A recently recognized interaction between Ca(2+) and cAMP is the Ca(2+)-induced cAMP formation in the mitochondrial matrix. Here we describe that soluble adenylyl cyclase (sAC) is expressed in H295R adrenocortical cells. Mitochondrial cAMP formation, monitored with a mitochondria-targeted fluorescent sensor (4mtH30), is enhanced by HCO3(-) and the Ca(2+) mobilizing agonist angiotensin II. The effect of angiotensin II is inhibited by 2-OHE, an inhibitor of sAC, and by RNA interference of sAC, but enhanced by an inhibitor of phosphodiesterase PDE2A. Heterologous expression of the Ca(2+) binding protein S100G within the mitochondrial matrix attenuates angiotensin II-induced mitochondrial cAMP formation. Inhibition and knockdown of sAC significantly reduce angiotensin II-induced aldosterone production. These data provide the first evidence for a cell-specific functional role of mitochondrial cAMP. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Zinc-dependent multi-conductance channel activity in mitochondria isolated from ischemic brain.

PubMed

Bonanni, Laura; Chachar, Mushtaque; Jover-Mengual, Teresa; Li, Hongmei; Jones, Adrienne; Yokota, Hidenori; Ofengeim, Dimitry; Flannery, Richard J; Miyawaki, Takahiro; Cho, Chang-Hoon; Polster, Brian M; Pypaert, Marc; Hardwick, J Marie; Sensi, Stefano L; Zukin, R Suzanne; Jonas, Elizabeth A

2006-06-21

Transient global ischemia is a neuronal insult that induces delayed cell death. A hallmark event in the early post-ischemic period is enhanced permeability of mitochondrial membranes. The precise mechanisms by which mitochondrial function is disrupted are, as yet, unclear. Here we show that global ischemia promotes alterations in mitochondrial membrane contact points, a rise in intramitochondrial Zn2+, and activation of large, multi-conductance channels in mitochondrial outer membranes by 1 h after insult. Mitochondrial channel activity was associated with enhanced protease activity and proteolytic cleavage of BCL-xL to generate its pro-death counterpart, deltaN-BCL-xL. The findings implicate deltaN-BCL-xL in large, multi-conductance channel activity. Consistent with this, large channel activity was mimicked by introduction of recombinant deltaN-BCL-xL to control mitochondria and blocked by introduction of a functional BCL-xL antibody to post-ischemic mitochondria via the patch pipette. Channel activity was also inhibited by nicotinamide adenine dinucleotide, indicative of a role for the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane. In vivo administration of the membrane-impermeant Zn2+ chelator CaEDTA before ischemia or in vitro application of the membrane-permeant Zn2+ chelator tetrakis-(2-pyridylmethyl) ethylenediamine attenuated channel activity, suggesting a requirement for Zn2+. These findings reveal a novel mechanism by which ischemic insults disrupt the functional integrity of the outer mitochondrial membrane and implicate deltaN-BCL-xL and VDAC in the large, Zn2+-dependent mitochondrial channels observed in post-ischemic hippocampal mitochondria.

Zinc-Dependent Multi-Conductance Channel Activity in Mitochondria Isolated from Ischemic Brain

PubMed Central

Bonanni, Laura; Chachar, Mushtaque; Jover-Mengual, Teresa; Li, Hongmei; Jones, Adrienne; Yokota, Hidenori; Ofengeim, Dimitry; Flannery, Richard J.; Miyawaki, Takahiro; Cho, Chang-Hoon; Polster, Brian M.; Pypaert, Marc; Hardwick, J. Marie; Sensi, Stefano L.; Zukin, R. Suzanne; Jonas, Elizabeth A.

2015-01-01

Transient global ischemia is a neuronal insult that induces delayed cell death. A hallmark event in the early post-ischemic period is enhanced permeability of mitochondrial membranes. The precise mechanisms by which mitochondrial function is disrupted are, as yet, unclear.Here we show that global ischemia promotes alterations in mitochondrial membrane contact points, a rise in intramitochondrial Zn2+, and activation of large, multi-conductance channels in mitochondrial outer membranes by 1 h after insult. Mitochondrial channel activity was associated with enhanced protease activity and proteolytic cleavage of BCL-xL to generate its pro-death counterpart, ΔN-BCL-xL. The findings implicate ΔN-BCL-xL in large, multi-conductance channel activity. Consistent with this, large channel activity was mimicked by introduction of recombinant ΔN-BCL-xL to control mitochondria and blocked by introduction of a functional BCL-xL antibody to post-ischemic mitochondria via the patch pipette. Channel activity was also inhibited by nicotinamide adenine dinucleotide, indicative of a role for the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane. In vivo administration of the membrane-impermeant Zn2+ chelator CaEDTA before ischemia or in vitro application of the membrane-permeant Zn2+ chelator tetrakis-(2-pyridylmethyl) ethylenediamine attenuated channel activity, suggesting a requirement for Zn2+. These findings reveal a novel mechanism by which ischemic insults disrupt the functional integrity of the outer mitochondrial membrane and implicate ΔNBCL-xL and VDAC in the large, Zn2+-dependent mitochondrial channels observed in post-ischemic hippocampal mitochondria. PMID:16793892

Nitric Oxide and Mitochondrial Function in Neurological Diseases.

PubMed

Ghasemi, Mehdi; Mayasi, Yunis; Hannoun, Anas; Eslami, Seyed Majid; Carandang, Raphael

2018-04-15

Mitochondria are key cellular organelles that play crucial roles in the energy production and regulation of cellular metabolism. Accumulating evidence suggests that mitochondrial activity can be modulated by nitric oxide (NO). As a key neurotransmitter in biologic systems, NO mediates the majority of its function through activation of the cyclic guanylyl cyclase (cGC) signaling pathway and S-nitrosylation of a variety of proteins involved in cellular functioning including those involved in mitochondrial biology. Moreover, excess NO or the formation of reactive NO species (RNS), e.g., peroxynitrite (ONOO - ), impairs mitochondrial functioning and this, in conjunction with nuclear events, eventually affects neuronal cell metabolism and survival, contributing to the pathogenesis of several neurodegenerative diseases. In this review we highlight the possible mechanisms underlying the noxious effects of excess NO and RNS on mitochondrial function including (i) negative effects on electron transport chain (ETC); (ii) ONOO - -mediated alteration in mitochondrial permeability transition; (iii) enhanced mitochondrial fragmentation and autophagy through S-nitrosylation of key proteins involved in this process such as dynamin-related protein 1 (DRP-1) and Parkin/PINK1 (protein phosphatase and tensin homolog-induced kinase 1) complex; (iv) alterations in the mitochondrial metabolic pathways including Krebs cycle, glycolysis, fatty acid metabolism, and urea cycle; and finally (v) mitochondrial ONOO - -induced nuclear toxicity and subsequent release of apoptosis-inducing factor (AIF) from mitochondria, causing neuronal cell death. These proposed mechanisms highlight the multidimensional nature of NO and its signaling in the mitochondrial function. Understanding the mechanisms by which NO mediates mitochondrial (dys)function can provide new insights into the treatment of neurodegenerative diseases. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Bruton's tyrosine kinase inhibition increases BCL-2 dependence and enhances sensitivity to venetoclax in chronic lymphocytic leukemia.

PubMed

Deng, J; Isik, E; Fernandes, S M; Brown, J R; Letai, A; Davids, M S

2017-10-01

Although the BTK inhibitor ibrutinib has transformed the management of patients with chronic lymphocytic leukemia (CLL), it does not induce substantial apoptosis in vitro, and as such the mechanisms underlying its ability to kill CLL cells are not well understood. Acalabrutinib, a more specific BTK inhibitor now in development, also appears to be highly effective in CLL, but the connection of its mechanism with CLL cell death is also unclear. Using dynamic BH3 profiling, we analyzed alterations in the function of the mitochondrial apoptotic pathway induced by ibrutinib and acalabrutinib. We studied CLL patient samples treated ex vivo with both drugs, as well as primary samples from CLL patients on clinical trials of both drugs. We found that BTK inhibition enhances mitochondrial BCL-2 dependence without significantly altering overall mitochondrial priming. Enhancement of BCL-2 dependence was accompanied by an increase in the pro-apoptotic protein BIM. In contrast, treatment with the selective BCL-2 inhibitor venetoclax enhanced overall mitochondrial priming without increasing BCL-2 dependence. Pre-treatment of CLL cells with either BTK inhibitor, whether ex vivo or in vivo in patients, enhanced killing by venetoclax. Our data suggest that BTK inhibition enhances mitochondrial BCL-2 dependence, supporting the ongoing development of clinical trials combining BTK and BCL-2 inhibition.

Bruton’s tyrosine kinase inhibition increases BCL-2 dependence and enhances sensitivity to venetoclax in chronic lymphocytic leukemia

PubMed Central

Deng, Jing; Isik, Elif; Fernandes, Stacey M.; Brown, Jennifer R.; Letai, Anthony; Davids, Matthew S.

2017-01-01

Although the BTK inhibitor ibrutinib has transformed the management of patients with CLL, it does not induce substantial apoptosis in vitro, and as such the mechanisms underlying its ability to kill CLL cells are not well understood. Acalabrutinib, a more specific BTK inhibitor now in development, also appears to be highly effective in CLL, but the connection of its mechanism with CLL cell death is also unclear. Using dynamic BH3 profiling, we analyzed alterations in the function of the mitochondrial apoptotic pathway induced by ibrutinib and acalabrutinib. We studied CLL patient samples treated ex vivo with both drugs, as well as primary samples from CLL patients on clinical trials of both drugs. We found that BTK inhibition enhances mitochondrial BCL-2 dependence without significantly altering overall mitochondrial priming. Enhancement of BCL-2 dependence was accompanied by an increase in the pro-apoptotic protein BIM. In contrast, treatment with the selective BCL-2 inhibitor venetoclax enhanced overall mitochondrial priming without increasing BCL-2 dependence. Pre-treatment of CLL cells with either BTK inhibitor, whether ex vivo or in vivo in patients, enhanced killing by venetoclax. Our data suggest that BTK inhibition enhances mitochondrial BCL2 dependence, supporting the ongoing development of clinical trials combining BTK and BCL-2 inhibition. PMID:28111464

The metabolic enhancer piracetam ameliorates the impairment of mitochondrial function and neurite outgrowth induced by ß-amyloid peptide

PubMed Central

Kurz, C; Ungerer, I; Lipka, U; Kirr, S; Schütt, T; Eckert, A; Leuner, K; Müller, WE

2010-01-01

Background and purpose: β-Amyloid peptide (Aβ) is implicated in the pathogenesis of Alzheimer's disease by initiating a cascade of events from mitochondrial dysfunction to neuronal death. The metabolic enhancer piracetam has been shown to improve mitochondrial dysfunction following brain aging and experimentally induced oxidative stress. Experimental approach: We used cell lines (PC12 and HEK cells) and murine dissociated brain cells. The protective effects of piracetam in vitro and ex vivo on Aβ-induced impairment of mitochondrial function (as mitochondrial membrane potential and ATP production), on secretion of soluble Aβ and on neurite outgrowth in PC12 cells were investigated. Key results: Piracetam improves mitochondrial function of PC12 cells and acutely dissociated brain cells from young NMRI mice following exposure to extracellular Aβ1-42. Similar protective effects against Aβ1-42 were observed in dissociated brain cells from aged NMRI mice, or mice transgenic for mutant human amyloid precursor protein (APP) treated with piracetam for 14 days. Soluble Aβ load was markedly diminished in the brain of those animals after treatment with piracetam. Aβ production by HEK cells stably transfected with mutant human APP was elevated by oxidative stress and this was reduced by piracetam. Impairment of neuritogenesis is an important consequence of Aβ-induced mitochondrial dysfunction and Aβ-induced reduction of neurite growth in PC12 cells was substantially improved by piracetam. Conclusion and implications: Our findings strongly support the concept of improving mitochondrial function as an approach to ameliorate the detrimental effects of Aβ on brain function. This article is commented on by Moncada, pp. 217–219 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.00706.x and to view related papers by Pravdic et al. and Puerta et al. visit http://dx.doi.org/10.1111/j.1476-5381.2010.00698.x and http://dx.doi.org/10.1111/j.1476-5381.2010.00663.x PMID:20218980

Alterations in Skeletal Muscle Indicators of Mitochondrial Structure and Biogenesis in Patients with Type 2 Diabetes and Heart Failure: Effects of Epicatechin Rich Cocoa

PubMed Central

Taub, Pam R.; Ramirez‐Sanchez, Israel; Ciaraldi, Theodore P.; Perkins, Guy; Murphy, Anne N.; Naviaux, Robert; Hogan, Michael; Maisel, Alan S.; Henry, Robert R.; Ceballos, Guillermo

2012-01-01

Abstract (‐)‐Epicatechin (Epi), a flavanol in cacao stimulates mitochondrial volume and cristae density and protein markers of skeletal muscle (SkM) mitochondrial biogenesis in mice. Type 2 diabetes mellitus (DM2) and heart failure (HF) are diseases associated with defects in SkM mitochondrial structure/function. A study was implemented to assess perturbations and to determine the effects of Epi‐rich cocoa in SkM mitochondrial structure and mediators of biogenesis. Five patients with DM2 and stage II/III HF consumed dark chocolate and a beverage containing approximately 100 mg of Epi per day for 3 months. We assessed changes in protein and/or activity levels of oxidative phosphorylation proteins, porin, mitofilin, nNOS, nitric oxide, cGMP, SIRT1, PGC1α, Tfam, and mitochondria volume and cristae abundance by electron microscopy from SkM. Apparent major losses in normal mitochondria structure were observed before treatment. Epi‐rich cocoa increased protein and/or activity of mediators of biogenesis and cristae abundance while not changing mitochondrial volume density. Epi‐rich cocoa treatment improves SkM mitochondrial structure and in an orchestrated manner, increases molecular markers of mitochondrial biogenesis resulting in enhanced cristae density. Future controlled studies are warranted using Epi‐rich cocoa (or pure Epi) to translate improved mitochondrial structure into enhanced cardiac and/or SkM muscle function. Clin Trans Sci 2012; Volume 5: 43–47 PMID:22376256

PDE 5 inhibitor improves insulin sensitivity by enhancing mitochondrial function in adipocytes.

PubMed

Yu, Hea Min; Chung, Hyo Kyun; Kim, Koon Soon; Lee, Jae Min; Hong, Jun Hwa; Park, Kang Seo

2017-11-04

Adipocytes are involved in many metabolic disorders. It was recently reported that phosphodiesterase type 5 (PDE5) is expressed in human adipose tissue. In addition, PDE5 inhibitors have been shown to improve insulin sensitivity in humans. However, the mechanism underlying the role of PDE5 inhibitors as an insulin sensitizer remains largely unknown. The present study was undertaken to investigate the role of the PDE5 inhibitor udenafil in insulin signaling in adipocytes and whether this is mediated through the regulation of mitochondrial function. To study the mechanism underlying the insulin sensitizing action of PDE5 inhibitors, we evaluated quantitative changes in protein or mRNA levels of mitochondrial oxidative phosphorylation (OxPhos) complex, oxygen consumption rate (OCR), and fatty acid oxidation with varying udenafil concentrations in 3T3-L1 cells. Our cell study suggested that udenafil enhanced the insulin signaling pathway in 3T3-L1 cells. Following udenafil treatment, basal mitochondrial OCR, maximal OxPhos capacity, and OxPhos gene expression significantly increased. Finally, we examined whether udenafil can affect the fatty acid oxidation process. Treatment of 3T3-L1 cells with udenafil (10 and 20 μM) significantly increased fatty acid oxidation rate in a dose-dependent manner. In addition, the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) significantly increased. We demonstrated that the PDE5 inhibitor udenafil enhances insulin sensitivity by improving mitochondrial function in 3T3-L1 cells. This might be the mechanism underlying the PDE5 inhibitor-enhanced insulin signaling in adipocytes. This also suggests that udenafil may provide benefit in the treatment of type 2 diabetes and other related cardiovascular diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Intrauterine Growth Retardation Increases the Susceptibility of Pigs to High-Fat Diet-Induced Mitochondrial Dysfunction in Skeletal Muscle

PubMed Central

Liu, Jingbo; Chen, Daiwen; Yao, Ying; Yu, Bing; Mao, Xiangbing; He, Jun; Huang, Zhiqing; Zheng, Ping

2012-01-01

It has been recognized that there is a relationship between prenatal growth restriction and the development of metabolic-related diseases in later life, a process involved in mitochondrial dysfunction. In addition, intrauterine growth retardation (IUGR) increases the susceptibility of offspring to high-fat (HF) diet-induced metabolic syndrome. Recent findings suggested that HF feeding decreased mitochondrial oxidative capacity and impaired mitochondrial function in skeletal muscle. Therefore, we hypothesized that the long-term consequences of IUGR on mitochondrial biogenesis and function make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. Normal birth weight (NBW), and IUGR pigs were allotted to control or HF diet in a completely randomized design, individually. After 4 weeks of feeding, growth performance and molecular pathways related to mitochondrial function were determined. The results showed that IUGR decreased growth performance and plasma insulin concentrations. In offspring fed a HF diet, IUGR was associated with enhanced plasma leptin levels, increased concentrations of triglyceride and malondialdehyde (MDA), and reduced glycogen and ATP contents in skeletal muscle. High fat diet-fed IUGR offspring exhibited decreased activities of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PD). These alterations in metabolic traits of IUGR pigs were accompanied by impaired mitochondrial respiration function, reduced mitochondrial DNA (mtDNA) contents, and down-regulated mRNA expression levels of genes responsible for mitochondrial biogenesis and function. In conclusion, our results suggest that IUGR make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. PMID:22523560

Mitochondrial proteome disruption in the diabetic heart through targeted epigenetic regulation at the mitochondrial heat shock protein 70 (mtHsp70) nuclear locus.

PubMed

Shepherd, Danielle L; Hathaway, Quincy A; Nichols, Cody E; Durr, Andrya J; Pinti, Mark V; Hughes, Kristen M; Kunovac, Amina; Stine, Seth M; Hollander, John M

2018-06-01

>99% of the mitochondrial proteome is nuclear-encoded. The mitochondrion relies on a coordinated multi-complex process for nuclear genome-encoded mitochondrial protein import. Mitochondrial heat shock protein 70 (mtHsp70) is a key component of this process and a central constituent of the protein import motor. Type 2 diabetes mellitus (T2DM) disrupts mitochondrial proteomic signature which is associated with decreased protein import efficiency. The goal of this study was to manipulate the mitochondrial protein import process through targeted restoration of mtHsp70, in an effort to restore proteomic signature and mitochondrial function in the T2DM heart. A novel line of cardiac-specific mtHsp70 transgenic mice on the db/db background were generated and cardiac mitochondrial subpopulations were isolated with proteomic evaluation and mitochondrial function assessed. MicroRNA and epigenetic regulation of the mtHsp70 gene during T2DM were also evaluated. MtHsp70 overexpression restored cardiac function and nuclear-encoded mitochondrial protein import, contributing to a beneficial impact on proteome signature and enhanced mitochondrial function during T2DM. Further, transcriptional repression at the mtHsp70 genomic locus through increased localization of H3K27me3 during T2DM insult was observed. Our results suggest that restoration of a key protein import constituent, mtHsp70, provides therapeutic benefit through attenuation of mitochondrial and contractile dysfunction in T2DM. Copyright © 2018 Elsevier Ltd. All rights reserved.

Protective effects of a natural product, curcumin, against amyloid β induced mitochondrial and synaptic toxicities in Alzheimer's disease

PubMed Central

Reddy, P Hemachandra; Manczak, Maria; Yin, Xiangling; Grady, Mary Catharine; Mitchell, Andrew; Kandimalla, Ramesh; Kuruva, Chandra Sekhar

2016-01-01

The purpose of our study was to investigate the protective effects of a natural product—‘curcumin’— in Alzheimer's disease (AD)-like neurons. Although much research has been done in AD, very little has been reported on the effects of curcumin on mitochondrial biogenesis, dynamics, function and synaptic activities. Therefore, the present study investigated the protective effects against amyloid β (Aβ) induced mitochondrial and synaptic toxicities. Using human neuroblastoma (SHSY5Y) cells, curcumin and Aβ, we studied the protective effects of curcumin against Aβ. Further, we also studied preventive (curcumin+Aβ) and intervention (Aβ+curcumin) effects of curcumin against Aβ in SHSY5Y cells. Using real time RT-PCR, immunoblotting and immunofluorescence analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis and synaptic genes. We also assessed mitochondrial function by measuring hydrogen peroxide, lipid peroxidation, cytochrome oxidase activity and mitochondrial ATP. Cell viability was studied using the MTT assay. Aβ was found to impair mitochondrial dynamics, reduce mitochondrial biogenesis and decrease synaptic activity and mitochondrial function. In contrast, curcumin enhanced mitochondrial fusion activity and reduced fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in curcumin treated cells. Interestingly, curcumin pre- and post-treated cells incubated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability and mitochondrial dynamics, mitochondrial biogenesis and synaptic activity. Further, the protective effects of curcumin were stronger in pretreated SHSY5Y cells than in post-treated cells, indicating that curcumin works better in prevention than treatment in AD-like neurons. Our findings suggest that curcumin is a promising drug molecule to treat AD patients. PMID:27521081

Protective effects of a natural product, curcumin, against amyloid β induced mitochondrial and synaptic toxicities in Alzheimer's disease.

PubMed

Reddy, P Hemachandra; Manczak, Maria; Yin, Xiangling; Grady, Mary Catharine; Mitchell, Andrew; Kandimalla, Ramesh; Kuruva, Chandra Sekhar

2016-12-01

The purpose of our study was to investigate the protective effects of a natural product-'curcumin'- in Alzheimer's disease (AD)-like neurons. Although much research has been done in AD, very little has been reported on the effects of curcumin on mitochondrial biogenesis, dynamics, function and synaptic activities. Therefore, the present study investigated the protective effects against amyloid β (Aβ) induced mitochondrial and synaptic toxicities. Using human neuroblastoma (SHSY5Y) cells, curcumin and Aβ, we studied the protective effects of curcumin against Aβ. Further, we also studied preventive (curcumin+Aβ) and intervention (Aβ+curcumin) effects of curcumin against Aβ in SHSY5Y cells. Using real time RT-PCR, immunoblotting and immunofluorescence analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis and synaptic genes. We also assessed mitochondrial function by measuring hydrogen peroxide, lipid peroxidation, cytochrome oxidase activity and mitochondrial ATP. Cell viability was studied using the MTT assay. Aβ was found to impair mitochondrial dynamics, reduce mitochondrial biogenesis and decrease synaptic activity and mitochondrial function. In contrast, curcumin enhanced mitochondrial fusion activity and reduced fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in curcumin treated cells. Interestingly, curcumin pre- and post-treated cells incubated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability and mitochondrial dynamics, mitochondrial biogenesis and synaptic activity. Further, the protective effects of curcumin were stronger in pretreated SHSY5Y cells than in post-treated cells, indicating that curcumin works better in prevention than treatment in AD-like neurons. Our findings suggest that curcumin is a promising drug molecule to treat AD patients. Copyright © 2016 American Federation for Medical Research.

Enhanced Mitochondrial Transient Receptor Potential Channel, Canonical Type 3-Mediated Calcium Handling in the Vasculature From Hypertensive Rats.

PubMed

Wang, Bin; Xiong, Shiqiang; Lin, Shaoyang; Xia, Weijie; Li, Qiang; Zhao, Zhigang; Wei, Xing; Lu, Zongshi; Wei, Xiao; Gao, Peng; Liu, Daoyan; Zhu, Zhiming

2017-07-15

Mitochondrial Ca 2+ homeostasis is fundamental to the regulation of mitochondrial reactive oxygen species (ROS) generation and adenosine triphosphate production. Recently, transient receptor potential channel, canonical type 3 (TRPC3), has been shown to localize to the mitochondria and to play a role in maintaining mitochondrial calcium homeostasis. Inhibition of TRPC3 attenuates vascular calcium influx in spontaneously hypertensive rats (SHRs). However, it remains elusive whether mitochondrial TRPC3 participates in hypertension by increasing mitochondrial calcium handling and ROS production. In this study we demonstrated increased TRPC3 expression in purified mitochondria in the vasculature from SHRs, which facilitates enhanced mitochondrial calcium uptake and ROS generation compared with Wistar-Kyoto rats. Furthermore, inhibition of TRPC3 by its specific inhibitor, Pyr3, significantly decreased the vascular mitochondrial ROS production and H 2 O 2 synthesis and increased adenosine triphosphate content. Administration of telmisartan can improve these abnormalities. This beneficial effect was associated with improvement of the mitochondrial respiratory function through recovering the activity of pyruvate dehydrogenase in the vasculature of SHRs. In vivo, chronic administration of telmisartan suppressed TRPC3-mediated excessive mitochondrial ROS generation and vasoconstriction in the vasculature of SHRs. More importantly, TRPC3 knockout mice exhibited significantly ameliorated hypertension through reduction of angiotensin II-induced mitochondrial ROS generation. Together, we give experimental evidence for a potential mechanism by which enhanced TRPC3 activity at the cytoplasmic and mitochondrial levels contributes to redox signaling and calcium dysregulation in the vasculature from SHRs. Angiotensin II or telmisartan can regulate [Ca 2+ ] mito , ROS production, and mitochondrial energy metabolism through targeting TRPC3. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Low testosterone levels are related to oxidative stress, mitochondrial dysfunction and altered subclinical atherosclerotic markers in type 2 diabetic male patients.

PubMed

Rovira-Llopis, Susana; Bañuls, Celia; de Marañon, Aranzazu M; Diaz-Morales, Noelia; Jover, Ana; Garzon, Sandra; Rocha, Milagros; Victor, Victor M; Hernandez-Mijares, Antonio

2017-07-01

Low testosterone levels in men are associated with type 2 diabetes and cardiovascular risk. However, the role of testosterone in mitochondrial function and leukocyte-endothelium interactions is unknown. Our aim was to evaluate the relationship between testosterone levels, metabolic parameters, oxidative stress, mitochondrial function, inflammation and leukocyte-endothelium interactions in type 2 diabetic patients. The study was performed in 280 male type 2 diabetic patients and 50 control subjects. Anthropometric and metabolic parameters, testosterone levels, reactive oxygen species (ROS) production, mitochondrial membrane potential, TNFα, adhesion molecules and leukocyte-endothelium cell interactions were evaluated. Testosterone levels were lower in diabetic patients. Total and mitochondrial ROS were increased and mitochondrial membrane potential, SOD and GSR expression levels were reduced in diabetic patients. TNFα, ICAM-1 and VCAM-1 levels, leukocyte rolling flux and adhesion were all enhanced in diabetic patients, while rolling velocity was reduced. Testosterone levels correlated negatively with glucose, HOMA-IR, HbA1c, triglycerides, nonHDL-c, ApoB, hs-CRP and AIP, and positively with HDL-c and ApoA1. The multivariable regression model showed that HDL-c, HOMA-IR and age were independently associated with testosterone. Furthermore, testosterone levels correlated positively with membrane potential and rolling velocity and negatively with ROS production, VCAM-1, rolling flux and adhesion. Our data highlight that low testosterone levels in diabetic men are related to impaired metabolic profile and mitochondrial function and enhanced inflammation and leukocyte-endothelium cell interaction, which leaves said patients at risk of cardiovascular events. Copyright © 2017 Elsevier Inc. All rights reserved.

Loss of Drp1 function alters OPA1 processing and changes mitochondrial membrane organization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moepert, Kristin; Hajek, Petr; Frank, Stephan

2009-08-01

RNAi mediated loss of Drp1 function changes mitochondrial morphology in cultured HeLa and HUVEC cells by shifting the balance of mitochondrial fission and fusion towards unopposed fusion. Over time, inhibition of Drp1 expression results in the formation of a highly branched mitochondrial network along with 'bulge'-like structures. These changes in mitochondrial morphology are accompanied by a reduction in levels of Mitofusin 1 (Mfn1) and 2 (Mfn2) and a modified proteolytic processing of OPA1 isoforms, resulting in the inhibition of cell proliferation. In addition, our data imply that bulge formation is driven by Mfn1 action along with particular proteolytic short-OPA1 (s-OPA1)more » variants: Loss of Mfn2 in the absence of Drp1 results in an increase of Mfn1 levels along with processed s-OPA1-isoforms, thereby enhancing continuous 'fusion' and bulge formation. Moreover, bulge formation might reflect s-OPA1 mitochondrial membrane remodeling activity, resulting in the compartmentalization of cytochrome c deposits. The proteins Yme1L and PHB2 appeared not associated with the observed enhanced OPA1 proteolysis upon RNAi of Drp1, suggesting the existence of other OPA1 processing controlling proteins. Taken together, Drp1 appears to affect the activity of the mitochondrial fusion machinery by unbalancing the protein levels of mitofusins and OPA1.« less

OxLDL enhances L-type Ca2+ currents via lysophosphatidylcholine-induced mitochondrial reactive oxygen species (ROS) production.

PubMed

Fearon, Ian M

2006-03-01

To examine the mechanisms underlying oxidised LDL- (oxLDL)-induced alterations in Ca(2+) currents, an effect which underlies altered vascular contractility and cardiac myocyte function. Ca(2+) currents (I(Ca)) were recorded by whole-cell patch-clamp in HEK293 cells expressing L-type Ca(2+) channel alpha(1C) subunits or isolated rat ventricular myocytes. oxLDL (but not native LDL) significantly enhanced recombinant I(Ca), an effect mimicked by 1 microM lysophosphatidylcholine (LPC). LPC failed to enhance I(Ca) either in mitochondrial electron transport chain-depleted rho(0) cells, or in the presence of rotenone (1 microM), or MPP(+) (10 microM). The LPC response was similarly ablated by ascorbate (200 microM) or TROLOX (500 microM) and by the mitochondria-targeted antioxidant, MitoQ (250 nM). In myocytes, enhancement of I(Ca) due to LPC was similarly abrogated with rotenone and MitoQ. These data suggest that LPC enhanced recombinant Ca(2+) currents due to increased mitochondrial ROS production. In support with this, LPC enhanced fluorescence in HEK293 cells and cardiac myocytes loaded with a ROS-sensitive mitochondrial dye, reduced mitotracker red. LPC up-regulates L-type Ca(2+) currents due to altered mitochondrial ROS production, an effect which mediates the response of the native I(Ca) in cardiac myocytes to oxLDL.

Enhanced J-protein interaction and compromised protein stability of mtHsp70 variants lead to mitochondrial dysfunction in Parkinson's disease.

PubMed

Goswami, Arvind Vittal; Samaddar, Madhuja; Sinha, Devanjan; Purushotham, Jaya; D'Silva, Patrick

2012-08-01

Parkinson's disease (PD) is the second most prevalent progressive neurological disorder commonly associated with impaired mitochondrial function in dopaminergic neurons. Although familial PD is multifactorial in nature, a recent genetic screen involving PD patients identified two mitochondrial Hsp70 variants (P509S and R126W) that are suggested in PD pathogenesis. However, molecular mechanisms underlying how mtHsp70 PD variants are centrally involved in PD progression is totally elusive. In this article, we provide mechanistic insights into the mitochondrial dysfunction associated with human mtHsp70 PD variants. Biochemically, the R126W variant showed severely compromised protein stability and was found highly susceptible to aggregation at physiological conditions. Strikingly, on the other hand, the P509S variant exhibits significantly enhanced interaction with J-protein cochaperones involved in folding and import machinery, thus altering the overall regulation of chaperone-mediated folding cycle and protein homeostasis. To assess the impact of mtHsp70 PD mutations at the cellular level, we developed yeast as a model system by making analogous mutations in Ssc1 ortholog. Interestingly, PD mutations in yeast (R103W and P486S) exhibit multiple in vivo phenotypes, which are associated with 'mitochondrial dysfunction', including compromised growth, impairment in protein translocation, reduced functional mitochondrial mass, mitochondrial DNA loss, respiratory incompetency and increased susceptibility to oxidative stress. In addition to that, R103W protein is prone to aggregate in vivo due to reduced stability, whereas P486S showed enhanced interaction with J-proteins, thus remarkably recapitulating the cellular defects that are observed in human PD variants. Taken together, our findings provide evidence in favor of direct involvement of mtHsp70 as a susceptibility factor in PD.

[Assessment of mitochondrial metabolic oxidative state in living cardiomyocytes with spectrally-resolved fluorescence lifetime spectroscopy of NAD(P)H].

PubMed

Cheng, Ying; Ren, Mingming; Niu, Yanyan; Qiao, Jianhua; Aneba, S; Chorvat, D; Chorvatova, A

2009-12-01

The primary function of cardiac mitochondria is the production of ATP to support heart contraction. Examination of the mitochondrial redox state is therefore crucially important to sensitively detect early signs of mitochondrial function in pathophysiological conditions, such as ischemia, diabetes and heart failure. We study fingerprinting of mitochondrial metabolic oxidative state in living cardiomyocytes with spectrally-resolved fluorescence lifetime spectroscopy of NAD(P)H, the principal electron donor in mitochondrial respiration responsible for vital ATP supply. Here NAD(P)H is studied as a marker for non-invasive fluorescent probing of the mitochondrial function. NAD(P) H fluorescence is recorded in cardiac cells following excitation with 375nm UV-light and detection by spectrally-resolved time-correlated single photon counting (TCSPC), based on the simultaneous measurement of the fluorescence spectra and fluorescence lifetimes. Modulation of NADH production and/or mitochondrial respiration is tested to study dynamic characteristics of NAD(P) H fluorescence decay. Our results show that at least a 3-exponential decay model, with 0.4-0.7ns, 1.2-1.9ns and 8.0-13. Ons lifetime pools is necessary to describe cardiomyocyte autofluorescence (AF) within 420-560nm spectral range. Increased mitochondrial NADH production by ketone bodies enhanced the fluorescence intensity, without significant change in fluorescent lifetimes. Rotenone, the inhibitor of Complex I of the mitochondrial respiratory chain, increased AF intensity and shortened the average fluorescence lifetime. Dinitrophenol (DNP), an uncoupling agent of the mitochondrial oxidative phosphorylation, lowered AF intensity, broadened the spectral shoulder at 520 nm and increased the average fluorescence lifetime. These effects are comparable to the study of NADH fluorescence decay in vitro. In the present contribution we demonstrated that spectrally-resolved fluorescence lifetime technique provides promising new tool for analysis of mitochondrial NAD(P) H fluorescence with good reproducibility in living cardiomyocytes. This approach will enhance our knowledge about cardiomyocyte oxidative metabolism and/or its dysfunction at a cellular level. In the future, this approach can prove helpful in the clinical diagnosis and treatment of mitochondrial disorder.

Mitochondrial Metabolism in Aging Heart

PubMed Central

Lesnefsky, Edward J.; Chen, Qun; Hoppel, Charles L.

2016-01-01

Altered mitochondrial metabolism is the underlying basis for the increased sensitivity in the aged heart to stress. The aged heart exhibits impaired metabolic flexibility, with a decreased capacity to oxidize fatty acids and enhanced dependence on glucose metabolism. Aging impairs mitochondrial oxidative phosphorylation, with a greater role played by the mitochondria located between the myofibrils, the interfibrillar mitochondria. With aging, there is a decrease in activity of complexes III and IV, which account for the decrease in respiration. Furthermore, aging decreases mitochondrial content among the myofibrils. The end result is that in the interfibrillar area there is an approximate 50% decrease in mitochondrial function, affecting all substrates. The defective mitochondria persist in the aged heart, leading to enhanced oxidant production and oxidative injury and the activation of oxidant signaling for cell death. Aging defects in mitochondria represent new therapeutic targets, whether by manipulation of the mitochondrial proteome, modulation of electron transport, activation of biogenesis or mitophagy, or the regulation of mitochondrial fission and fusion. These mechanisms provide new ways to attenuate cardiac disease in elders by preemptive treatment of age-related defects, in contrast to the treatment of disease-induced dysfunction. PMID:27174952

Homocysteine activates T cells by enhancing endoplasmic reticulum-mitochondria coupling and increasing mitochondrial respiration.

PubMed

Feng, Juan; Lü, Silin; Ding, Yanhong; Zheng, Ming; Wang, Xian

2016-06-01

Hyperhomocysteinemia (HHcy) accelerates atherosclerosis by increasing proliferation and stimulating cytokine secretion in T cells. However, whether homocysteine (Hcy)-mediated T cell activation is associated with metabolic reprogramming is unclear. Here, our in vivo and in vitro studies showed that Hcy-stimulated splenic T-cell activation in mice was accompanied by increased levels of mitochondrial reactive oxygen species (ROS) and calcium, mitochondrial mass and respiration. Inhibiting mitochondrial ROS production and calcium signals or blocking mitochondrial respiration largely blunted Hcy-induced T-cell interferon γ (IFN-γ) secretion and proliferation. Hcy also enhanced endoplasmic reticulum (ER) stress in T cells, and inhibition of ER stress with 4-phenylbutyric acid blocked Hcy-induced T-cell activation. Mechanistically, Hcy increased ER-mitochondria coupling, and uncoupling ER-mitochondria by the microtubule inhibitor nocodazole attenuated Hcy-stimulated mitochondrial reprogramming, IFN-γ secretion and proliferation in T cells, suggesting that juxtaposition of ER and mitochondria is required for Hcy-promoted mitochondrial function and T-cell activation. In conclusion, Hcy promotes T-cell activation by increasing ER-mitochondria coupling and regulating metabolic reprogramming.

The Permeability Transition Pore Controls Cardiac Mitochondrial Maturation and Myocyte Differentiation

PubMed Central

Hom, Jennifer R.; Quintanilla, Rodrigo A.; Hoffman, David L.; Karen L., de Mesy Bentley; Molkentin, Jeffery D.; Sheu, Shey-Shing; Porter, George A.

2011-01-01

SUMMARY Although mature myocytes rely on mitochondria as the primary source of energy, the role of mitochondria in the developing heart is not well known. Here, we find closure of the mitochondrial permeability transition pore (mPTP) drives maturation of mitochondrial structure and function and myocyte differentiation. Cardiomyocytes at embryonic day (E) 9.5, when compared to E13.5, displayed fragmented mitochondria with few cristae, a less polarized mitochondrial membrane potential, higher reactive oxygen species (ROS) levels, and an open mPTP. Pharmacologic and genetic closing of the mPTP yielded maturation of mitochondrial structure and function, lowered ROS, and increased myocyte differentiation (measured by counting Z-bands). Furthermore, myocyte differentiation was inhibited and enhanced with oxidant and antioxidant treatment, respectively, suggesting that redox signaling pathways lie downstream of mitochondria to regulate cardiac myocyte differentiation. PMID:21920313

Drp1-dependent mitophagy protects against cisplatin-induced apoptosis of renal tubular epithelial cells by improving mitochondrial function

PubMed Central

Qi, Jia; Duan, Suyan; Huang, Zhimin; Zhang, Chengning; Wu, Lin; Zeng, Ming; Zhang, Bo; Wang, Ningning; Mao, Huijuan; Zhang, Aihua; Xing, Changying; Yuan, Yanggang

2017-01-01

Cisplatin chemotherapy often causes acute kidney injury (AKI) in cancer patients. There is increasing evidence that mitochondrial dysfunction plays an important role in cisplatin-induced nephrotoxicity. Degradation of damaged mitochondria is carried out by mitophagy. Although mitophagy is considered of particular importance in protecting against AKI, little is known of the precise role of mitophagy and its molecular mechanisms during cisplatin-induced nephrotoxicity. Also, evidence that activation of mitophagy improved mitochondrial function is lacking. Furthermore, several evidences have shown that mitochondrial fission coordinates with mitophagy. The aim of this study was to investigate whether activation of mitophagy protects against mitochondrial dysfunction and renal proximal tubular cells injury during cisplatin treatment. The effect of mitochondrial fission on mitophagy was also investigated. In cultured human renal proximal tubular cells, we observed that 3-methyladenine, a pharmacological inhibitor of autophagy, blocked mitophagy and exacerbated cisplatin-induced mitochondrial dysfunction and cells injury. In contrast, autophagy activator rapamycin enhanced mitophagy and protected against the harmful effects of cisplatin on mitochondrial function and cells viability. Suppression of mitochondrial fission by knockdown of its main regulator dynamin-related protein-1 (Drp1) decreased cisplatin-induced mitophagy. Meanwhile, Drp1 suppression protected against cisplatin-induced cells injury by inhibiting mitochondrial dysfunction. Our results provide evidence that Drp1-depedent mitophagy has potential as renoprotective targets for the treatment of cisplatin-induced AKI. PMID:28423497

Downregulation of a mitochondria associated protein SLP-2 inhibits tumor cell motility, proliferation and enhances cell sensitivity to chemotherapeutic reagents.

PubMed

Wang, Yueqi; Cao, Wenfeng; Yu, Zaicheng; Liu, Zhihua

2009-09-01

Results from tissue microarray in this study and our previous reports revealed that stomatin-like protein 2 (SLP-2) is notably associated with tumorigenesis and metastasis. Many members of stomatin family are involved in tumor as mitochondrial component, and recent study has revealed that SLP-2 may also function in mitochondria. To further investigate the function of SLP-2, we used siRNA target SLP-2. Data showed that knock-down of SLP-2 potently inhibited cell motility, proliferation and slightly altered cell cycle without any significant change of apoptosis. Moreover, by combined application with different chemotherapeutic reagents, we observed the enhancement of cell chemosensitivity by SLP-2 depletion. We also confirmed that, SLP-2 localizes in mitochondria, affects mitochondrial membrane potential (MMP) and ATP production. We conclude that, SLP-2 is a mitochondrial protein and therefore, functions in energy process by MMP maintenance, and subsequently affecting cell motility, proliferation and chemosensitivity.

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/−-IRS-1+/− Double Heterozygous (IR-IRS1dh) Mice

PubMed Central

Franko, Andras; Kunze, Alexander; Böse, Marlen; von Kleist-Retzow, Jürgen-Christoph; Paulsson, Mats; Hartmann, Ursula; Wiesner, Rudolf J.

2017-01-01

Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR)+/−-insulin receptor substrate-1 (IRS-1)+/− double heterozygous (IR-IRS1dh) mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver. PMID:28556799

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/--IRS-1+/- Double Heterozygous (IR-IRS1dh) Mice.

PubMed

Franko, Andras; Kunze, Alexander; Böse, Marlen; von Kleist-Retzow, Jürgen-Christoph; Paulsson, Mats; Hartmann, Ursula; Wiesner, Rudolf J

2017-05-30

Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR) +/- -insulin receptor substrate-1 (IRS-1) +/- double heterozygous (IR-IRS1dh) mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver.

Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health

PubMed Central

Villamena, Frederick A.

2018-01-01

Impaired mitochondrial function often results in excessive production of reactive oxygen species (ROS) and is involved in the etiology of many chronic diseases, including cardiovascular disease, diabetes, neurodegenerative disorders, and cancer. Moderate levels of mitochondrial ROS, however, can protect against chronic disease by inducing upregulation of mitochondrial capacity and endogenous antioxidant defense. This phenomenon, referred to as mitohormesis, is induced through increased reliance on mitochondrial respiration, which can occur through diet or exercise. Nutritional ketosis is a safe and physiological metabolic state induced through a ketogenic diet low in carbohydrate and moderate in protein. Such a diet increases reliance on mitochondrial respiration and may, therefore, induce mitohormesis. Furthermore, the ketone β-hydroxybutyrate (BHB), which is elevated during nutritional ketosis to levels no greater than those resulting from fasting, acts as a signaling molecule in addition to its traditionally known role as an energy substrate. BHB signaling induces adaptations similar to mitohormesis, thereby expanding the potential benefit of nutritional ketosis beyond carbohydrate restriction. This review describes the evidence supporting enhancement of mitochondrial function and endogenous antioxidant defense in response to nutritional ketosis, as well as the potential mechanisms leading to these adaptations. PMID:29607218

Dopamine D2 receptor-mediated neuroprotection in a G2019S Lrrk2 genetic model of Parkinson's disease.

PubMed

Tozzi, Alessandro; Tantucci, Michela; Marchi, Saverio; Mazzocchetti, Petra; Morari, Michele; Pinton, Paolo; Mancini, Andrea; Calabresi, Paolo

2018-02-12

Parkinson's disease (PD) is a neurodegenerative disorder in which genetic and environmental factors synergistically lead to loss of midbrain dopamine (DA) neurons. Mutation of leucine-rich repeated kinase2 (Lrrk2) genes is responsible for the majority of inherited familial cases of PD and can also be found in sporadic cases. The pathophysiological role of this kinase has to be fully understood yet. Hyperactivation of Lrrk2 kinase domain might represent a predisposing factor for both enhanced striatal glutamatergic release and mitochondrial vulnerability to environmental factors that are observed in PD. To investigate possible alterations of striatal susceptibility to mitochondrial dysfunction, we performed electrophysiological recordings from the nucleus striatum of a G2019S Lrrk2 mouse model of PD, as well as molecular and morphological analyses of G2019S Lrrk2-expressing SH-SY5Y neuroblastoma cells. In G2019S mice, we found reduced striatal DA levels, according to the hypothesis of alteration of dopaminergic transmission, and increased loss of field potential induced by the mitochondrial complex I inhibitor rotenone. This detrimental effect is reversed by the D2 DA receptor agonist quinpirole via the inhibition of the cAMP/PKA intracellular pathway. Analysis of mitochondrial functions in G2019S Lrrk2-expressing SH-SY5Y cells revealed strong rotenone-induced oxidative stress characterized by reduced Ca 2+ buffering capability and ATP synthesis, production of reactive oxygen species, and increased mitochondrial fragmentation. Importantly, quinpirole was able to prevent all these changes. We suggest that the G2019S-Lrrk2 mutation is a predisposing factor for enhanced striatal susceptibility to mitochondrial dysfunction induced by exposure to mitochondrial environmental toxins and that the D2 receptor stimulation is neuroprotective on mitochondrial function, via the inhibition of cAMP/PKA intracellular pathway. We suggest new possible neuroprotective strategies for patients carrying this genetic alteration based on drugs specifically targeting Lrrk2 kinase domain and mitochondrial functionality.

Inositol trisphosphate receptor-mediated Ca2+ signalling stimulates mitochondrial function and gene expression in core myopathy patients.

PubMed

Suman, Matteo; Sharpe, Jenny A; Bentham, Robert B; Kotiadis, Vassilios N; Menegollo, Michela; Pignataro, Viviana; Molgó, Jordi; Muntoni, Francesco; Duchen, Michael R; Pegoraro, Elena; Szabadkai, Gyorgy

2018-07-01

Core myopathies are a group of childhood muscle disorders caused by mutations of the ryanodine receptor (RyR1), the Ca2+ release channel of the sarcoplasmic reticulum. These mutations have previously been associated with elevated inositol trisphosphate receptor (IP3R) levels in skeletal muscle myotubes derived from patients. However, the functional relevance and the relationship of IP3R mediated Ca2+ signalling with the pathophysiology of the disease is unclear. It has also been suggested that mitochondrial dysfunction underlies the development of central and diffuse multi-mini-cores, devoid of mitochondrial activity, which is a key pathological consequence of RyR1 mutations. Here we used muscle biopsies of central core and multi-minicore disease patients with RyR1 mutations, as well as cellular and in vivo mouse models of the disease to characterize global cellular and mitochondrial Ca2+ signalling, mitochondrial function and gene expression associated with the disease. We show that RyR1 mutations that lead to the depletion of the channel are associated with increased IP3-mediated nuclear and mitochondrial Ca2+ signals and increased mitochondrial activity. Moreover, western blot and microarray analysis indicated enhanced mitochondrial biogenesis at the transcriptional and protein levels and was reflected in increased mitochondrial DNA content. The phenotype was recapitulated by RYR1 silencing in mouse cellular myotube models. Altogether, these data indicate that remodelling of skeletal muscle Ca2+ signalling following loss of functional RyR1 mediates bioenergetic adaptation.

Magnesium and calcium-enriched deep-sea water promotes mitochondrial biogenesis by AMPK-activated signals pathway in 3T3-L1 preadipocytes.

PubMed

Ha, Byung Geun; Moon, Deok-Soo; Kim, Hyeon Ju; Shon, Yun Hee

2016-10-01

Recent studies showed that deficiencies of essential minerals including Mg, Ca, and K, and trace minerals including Se, Zn, and V, have implications for the development, prevention, and treatment of several chronic diseases including obesity and type 2 diabetes. Our previous studies revealed that balanced deep-sea water (BDSW), which is composed of desalinated water enriched with Mg and Ca, has potential as a treatment for diabetes and obesity. In this study, to determine whether BDSW regulates mitochondrial biogenesis and function, we investigated its effects on mitochondrial DNA (mtDNA) content, mitochondrial enzyme activity, expression of key transcription factors and mitochondria-specific genes, phosphorylation of signaling molecules associated with mitochondrial biogenesis, and mitochondrial function in 3T3-L1 preadipocytes. BDSW increased mitochondrial biogenesis in a dose-dependent manner. Quantitative real-time PCR revealed that BDSW enhances expression of PGC1-α, NRF1, and TFAM genes. Upregulation of these genes was supported by increased mitochondria staining, CytC oxidase activity, and AMPK phosphorylation. The stimulatory effect of BDSW on mitochondrial biogenesis and function suggests a novel mechanism for BDSW-induced anti-diabetic and anti-obesity action. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Oxidative stress–induced mitochondrial dysfunction drives inflammation and airway smooth muscle remodeling in patients with chronic obstructive pulmonary disease

PubMed Central

Wiegman, Coen H.; Michaeloudes, Charalambos; Haji, Gulammehdi; Narang, Priyanka; Clarke, Colin J.; Russell, Kirsty E.; Bao, Wuping; Pavlidis, Stelios; Barnes, Peter J.; Kanerva, Justin; Bittner, Anton; Rao, Navin; Murphy, Michael P.; Kirkham, Paul A.; Chung, Kian Fan; Adcock, Ian M.; Brightling, Christopher E.; Davies, Donna E.; Finch, Donna K.; Fisher, Andrew J.; Gaw, Alasdair; Knox, Alan J.; Mayer, Ruth J.; Polkey, Michael; Salmon, Michael; Singh, David

2015-01-01

Background Inflammation and oxidative stress play critical roles in patients with chronic obstructive pulmonary disease (COPD). Mitochondrial oxidative stress might be involved in driving the oxidative stress–induced pathology. Objective We sought to determine the effects of oxidative stress on mitochondrial function in the pathophysiology of airway inflammation in ozone-exposed mice and human airway smooth muscle (ASM) cells. Methods Mice were exposed to ozone, and lung inflammation, airway hyperresponsiveness (AHR), and mitochondrial function were determined. Human ASM cells were isolated from bronchial biopsy specimens from healthy subjects, smokers, and patients with COPD. Inflammation and mitochondrial function in mice and human ASM cells were measured with and without the presence of the mitochondria-targeted antioxidant MitoQ. Results Mice exposed to ozone, a source of oxidative stress, had lung inflammation and AHR associated with mitochondrial dysfunction and reflected by decreased mitochondrial membrane potential (ΔΨm), increased mitochondrial oxidative stress, and reduced mitochondrial complex I, III, and V expression. Reversal of mitochondrial dysfunction by the mitochondria-targeted antioxidant MitoQ reduced inflammation and AHR. ASM cells from patients with COPD have reduced ΔΨm, adenosine triphosphate content, complex expression, basal and maximum respiration levels, and respiratory reserve capacity compared with those from healthy control subjects, whereas mitochondrial reactive oxygen species (ROS) levels were increased. Healthy smokers were intermediate between healthy nonsmokers and patients with COPD. Hydrogen peroxide induced mitochondrial dysfunction in ASM cells from healthy subjects. MitoQ and Tiron inhibited TGF-β–induced ASM cell proliferation and CXCL8 release. Conclusions Mitochondrial dysfunction in patients with COPD is associated with excessive mitochondrial ROS levels, which contribute to enhanced inflammation and cell hyperproliferation. Targeting mitochondrial ROS represents a promising therapeutic approach in patients with COPD. PMID:25828268

Mitochondria-Division Inhibitor 1 Protects Against Amyloid-β induced Mitochondrial Fragmentation and Synaptic Damage in Alzheimer's Disease.

PubMed

Reddy, P Hemachandra; Manczak, Maria; Yin, XiangLing

2017-01-01

The purpose our study was to determine the protective effects of mitochondria division inhibitor 1 (Mdivi1) in Alzheimer's disease (AD). Mdivi1 is hypothesized to reduce excessive fragmentation of mitochondria and mitochondrial dysfunction in AD neurons. Very little is known about whether Mdivi1 can confer protective effects in AD. In the present study, we sought to determine the protective effects of Mdivi1 against amyloid-β (Aβ)- and mitochondrial fission protein, dynamin-related protein 1 (Drp1)-induced excessive fragmentation of mitochondria in AD progression. We also studied preventive (Mdivi1+Aβ42) and intervention (Aβ42+Mdivi1) effects against Aβ42 in N2a cells. Using real-time RT-PCR and immunoblotting analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis, and synaptic genes. We also assessed mitochondrial function by measuring H2O2, lipid peroxidation, cytochrome oxidase activity, and mitochondrial ATP. MTT assays were used to assess the cell viability. Aβ42 was found to impair mitochondrial dynamics, lower mitochondrial biogenesis, lower synaptic activity, and lower mitochondrial function. On the contrary, Mdivi1 enhanced mitochondrial fusion activity, lowered fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in Mdivi1-treated cells. Interestingly, Mdivi1 pre- and post-treated cells treated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability, mitochondrial dynamics, mitochondrial biogenesis, and synaptic activity. The protective effects of Mdivi1 were stronger in N2a+Aβ42 pre-treated with Mdivi1, than in N2a+Aβ42 cells than Mdivi1 post-treated cells, indicating that Mdivi1 works better in prevention than treatment in AD like neurons.

Selections that isolate recombinant mitochondrial genomes in animals

PubMed Central

Ma, Hansong; O'Farrell, Patrick H

2015-01-01

Homologous recombination is widespread and catalyzes evolution. Nonetheless, its existence in animal mitochondrial DNA is questioned. We designed selections for recombination between co-resident mitochondrial genomes in various heteroplasmic Drosophila lines. In four experimental settings, recombinant genomes became the sole or dominant genome in the progeny. Thus, selection uncovers occurrence of homologous recombination in Drosophila mtDNA and documents its functional benefit. Double-strand breaks enhanced recombination in the germline and revealed somatic recombination. When the recombination partner was a diverged Drosophila melanogaster genome or a genome from a different species such as Drosophila yakuba, sequencing revealed long continuous stretches of exchange. In addition, the distribution of sequence polymorphisms in recombinants allowed us to map a selected trait to a particular region in the Drosophila mitochondrial genome. Thus, recombination can be harnessed to dissect function and evolution of mitochondrial genome. DOI: http://dx.doi.org/10.7554/eLife.07247.001 PMID:26237110

Medroxyprogesterone Acetate Antagonizes Estrogen Up-Regulation of Brain Mitochondrial Function

PubMed Central

Irwin, Ronald W.; Yao, Jia; Ahmed, Syeda S.; Hamilton, Ryan T.; Cadenas, Enrique

2011-01-01

The impact of clinical progestins used in contraception and hormone therapies on the metabolic capacity of the brain has long-term implications for neurological health in pre- and postmenopausal women. Previous analyses indicated that progesterone and 17β-estradiol (E2) sustain and enhance brain mitochondrial energy-transducing capacity. Herein we determined the impact of the clinical progestin, medroxyprogesterone acetate (MPA), on glycolysis, oxidative stress, and mitochondrial function in brain. Ovariectomized female rats were treated with MPA, E2, E2+MPA, or vehicle with ovary-intact rats serving as a positive control. MPA alone and MPA plus E2 resulted in diminished mitochondrial protein levels for pyruvate dehydrogenase, cytochrome oxidase, ATP synthase, manganese-superoxide dismutase, and peroxiredoxin V. MPA alone did not rescue the ovariectomy-induced decrease in mitochondrial bioenergetic function, whereas the coadministration of E2 and MPA exhibited moderate efficacy. However, the coadministration of MPA was detrimental to antioxidant defense, including manganese-superoxide dismutase activity/expression and peroxiredoxin V expression. Accumulated lipid peroxides were cleared by E2 treatment alone but not in combination with MPA. Furthermore, MPA abolished E2-induced enhancement of mitochondrial respiration in primary cultures of the hippocampal neurons and glia. Collectively these findings indicate that the effects of MPA differ significantly from the bioenergetic profile induced by progesterone and that, overall, MPA induced a decline in glycolytic and oxidative phosphorylation protein and activity. These preclinical findings on the basis of acute exposure to MPA raise concerns regarding neurological health after chronic use of MPA in contraceptive and hormone therapy. PMID:21159850

[Anesthetic management for patients with mitochondrial disease].

PubMed

Imai, Yousuke; Yamada, Yoshitsugu

2014-01-01

Mitochondrial diseases are caused by a decrease in ATP production due to mutations of mitochondrial or mitochondria-related nuclear DNA. Their effects are likely to appear in tissues with a high energy demand, including skeletal muscle, nervous, and cardiovascular systems. Cardiac manifestations of mitochondrial diseases can be divided into cardiomyopathies, which are primarily hypertrophic and dilated cardiomyopathies, and electropathies, which are primarily conduction system disease and ventricular pre-excitation. The first principle of anesthesia for patients with mitochondrial diseases is to avoid any additional burden on the already declined metabolic functions. Appropriate oxygenation, minimization of the oxygen demand, stable cardiovascular management, maintenance of a normal blood glucose level and body temperature, and effective perioperative pain control are of importance. Most anesthetics have been reported to reduce mitochondrial functions, and although enhancement of the sensitivity and prolongation of the duration of action have been reported, they are clinically used with no major problems. Detailed preoperative evaluation of the disease condition and careful intraoperative monitoring are important for the prevention of perioperative complications.

Regulation of mitochondria-dynactin interaction and mitochondrial retrograde transport in axons.

PubMed

Drerup, Catherine M; Herbert, Amy L; Monk, Kelly R; Nechiporuk, Alex V

2017-04-17

Mitochondrial transport in axons is critical for neural circuit health and function. While several proteins have been found that modulate bidirectional mitochondrial motility, factors that regulate unidirectional mitochondrial transport have been harder to identify. In a genetic screen, we found a zebrafish strain in which mitochondria fail to attach to the dynein retrograde motor. This strain carries a loss-of-function mutation in actr10 , a member of the dynein-associated complex dynactin. The abnormal axon morphology and mitochondrial retrograde transport defects observed in actr10 mutants are distinct from dynein and dynactin mutant axonal phenotypes. In addition, Actr10 lacking the dynactin binding domain maintains its ability to bind mitochondria, arguing for a role for Actr10 in dynactin-mitochondria interaction. Finally, genetic interaction studies implicated Drp1 as a partner in Actr10-dependent mitochondrial retrograde transport. Together, this work identifies Actr10 as a factor necessary for dynactin-mitochondria interaction, enhancing our understanding of how mitochondria properly localize in axons.

Phosphatidylserine transport by Ups2-Mdm35 in respiration-active mitochondria.

PubMed

Miyata, Non; Watanabe, Yasunori; Tamura, Yasushi; Endo, Toshiya; Kuge, Osamu

2016-07-04

Phosphatidylethanolamine (PE) is an essential phospholipid for mitochondrial functions and is synthesized mainly by phosphatidylserine (PS) decarboxylase at the mitochondrial inner membrane. In Saccharomyces cerevisiae, PS is synthesized in the endoplasmic reticulum (ER), such that mitochondrial PE synthesis requires PS transport from the ER to the mitochondrial inner membrane. Here, we provide evidence that Ups2-Mdm35, a protein complex localized at the mitochondrial intermembrane space, mediates PS transport for PE synthesis in respiration-active mitochondria. UPS2- and MDM35-null mutations greatly attenuated conversion of PS to PE in yeast cells growing logarithmically under nonfermentable conditions, but not fermentable conditions. A recombinant Ups2-Mdm35 fusion protein exhibited phospholipid-transfer activity between liposomes in vitro. Furthermore, UPS2 expression was elevated under nonfermentable conditions and at the diauxic shift, the metabolic transition from glycolysis to oxidative phosphorylation. These results demonstrate that Ups2-Mdm35 functions as a PS transfer protein and enhances mitochondrial PE synthesis in response to the cellular metabolic state. © 2016 Miyata et al.

Mitochondrial Division Inhibitor 1 (mdivi-1) Protects Neurons against Excitotoxicity through the Modulation of Mitochondrial Function and Intracellular Ca2+ Signaling.

PubMed

Ruiz, Asier; Alberdi, Elena; Matute, Carlos

2018-01-01

Excessive dynamin related protein 1 (Drp1)-triggered mitochondrial fission contributes to apoptosis under pathological conditions and therefore it has emerged as a promising therapeutic target. Mitochondrial division inhibitor 1 (mdivi-1) inhibits Drp1-dependent mitochondrial fission and is neuroprotective in several models of brain ischemia and neurodegeneration. However, mdivi-1 also modulates mitochondrial function and oxidative stress independently of Drp1, and consequently the mechanisms through which it protects against neuronal injury are more complex than previously foreseen. In this study, we have analyzed the effects of mdivi-1 on mitochondrial dynamics, Ca 2+ signaling, mitochondrial bioenergetics and cell viability during neuronal excitotoxicity in vitro . Time-lapse fluorescence microscopy revealed that mdivi-1 blocked NMDA-induced mitochondrial fission but not that triggered by sustained AMPA receptor activation, showing that mdivi-1 inhibits excitotoxic mitochondrial fragmentation in a source specific manner. Similarly, mdivi-1 strongly reduced NMDA-triggered necrotic-like neuronal death and, to a lesser extent, AMPA-induced toxicity. Interestingly, neuroprotection provided by mdivi-1 against NMDA, but not AMPA, correlated with a reduction in cytosolic Ca 2+ ([Ca 2+ ] cyt ) overload and calpain activation indicating additional cytoprotective mechanisms. Indeed, mdivi-1 depolarized mitochondrial membrane and depleted ER Ca 2+ content, leading to attenuation of mitochondrial [Ca 2+ ] increase and enhancement of the integrated stress response (ISR) during NMDA receptor activation. Finally, lentiviral knockdown of Drp1 did not rescue NMDA-induced mitochondrial fission and toxicity, indicating that neuroprotective activity of mdivi-1 is Drp1-independent. Together, these results suggest that mdivi-1 induces a Drp1-independent protective phenotype that prevents predominantly NMDA receptor-mediated excitotoxicity through the modulation of mitochondrial function and intracellular Ca 2+ signaling.

Exercise Promotes Healthy Aging of Skeletal Muscle

PubMed Central

Cartee, Gregory D.; Hepple, Russell T.; Bamman, Marcas M.; Zierath, Juleen R.

2016-01-01

Primary aging is the progressive and inevitable process of bodily deterioration during adulthood. In skeletal muscle, primary aging causes defective mitochondrial energetics, and reduced muscle mass. Secondary aging refers to additional deleterious structural and functional age-related changes caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes “healthy aging” by inducing modifications in skeletal muscle. PMID:27304505

Mitochondrial transfer of mesenchymal stem cells effectively protects corneal epithelial cells from mitochondrial damage.

PubMed

Jiang, Dan; Gao, Fei; Zhang, Yuelin; Wong, David Sai Hung; Li, Qing; Tse, Hung-Fat; Xu, Goufeng; Yu, Zhendong; Lian, Qizhou

2016-11-10

Recent studies have demonstrated that mesenchymal stem cells (MSCs) can donate mitochondria to airway epithelial cells and rescue mitochondrial damage in lung injury. We sought to determine whether MSCs could donate mitochondria and protect against oxidative stress-induced mitochondrial dysfunction in the cornea. Co-culturing of MSCs and corneal epithelial cells (CECs) indicated that the efficiency of mitochondrial transfer from MSCs to CECs was enhanced by Rotenone (Rot)-induced oxidative stress. The efficient mitochondrial transfer was associated with increased formation of tunneling nanotubes (TNTs) between MSCs and CECs, tubular connections that allowed direct intercellular communication. Separation of MSCs and CECs by a transwell culture system revealed no mitochiondrial transfer from MSCs to CECs and mitochondrial function was impaired when CECs were exposed to Rot challenge. CECs with or without mitochondrial transfer from MSCs displayed a distinct survival capacity and mitochondrial oxygen consumption rate. Mechanistically, increased filopodia outgrowth in CECs for TNT formation was associated with oxidative inflammation-activated NFκB/TNFαip2 signaling pathways that could be attenuated by reactive oxygen species scavenger N-acetylcysteine (NAC) treatment. Furthermore, MSCs grown on a decellularized porcine corneal scaffold were transplanted onto an alkali-injured eye in a rabbit model. Enhanced corneal wound healing was evident following healthy MSC scaffold transplantation. And transferred mitochondria was detected in corneal epithelium. In conclusion, mitochondrial transfer from MSCs provides novel protection for the cornea against oxidative stress-induced mitochondrial damage. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.

Mitochondrial-Based Therapeutics for the Treatment of Spinal Cord Injury: Mitochondrial Biogenesis as a Potential Pharmacological Target

PubMed Central

Scholpa, Natalie E.

2017-01-01

Spinal cord injury (SCI) is characterized by an initial trauma followed by a progressive cascade of damage referred to as secondary injury. A hallmark of secondary injury is vascular disruption leading to vasoconstriction and decreased oxygen delivery, which directly reduces the ability of mitochondria to maintain homeostasis and leads to loss of ATP-dependent cellular functions, calcium overload, excitotoxicity, and oxidative stress, further exacerbating injury. Restoration of mitochondria dysfunction during the acute phases of secondary injury after SCI represents a potentially effective therapeutic strategy. This review discusses the past and present pharmacological options for the treatment of SCI as well as current research on mitochondria-targeted approaches. Increased antioxidant activity, inhibition of the mitochondrial permeability transition, alternate energy sources, and manipulation of mitochondrial morphology are among the strategies under investigation. Unfortunately, many of these tactics address single aspects of mitochondrial dysfunction, ultimately proving largely ineffective. Therefore, this review also examines the unexplored therapeutic efficacy of pharmacological enhancement of mitochondrial biogenesis, which has the potential to more comprehensively improve mitochondrial function after SCI. PMID:28935700

Mitochondrial-Based Therapeutics for the Treatment of Spinal Cord Injury: Mitochondrial Biogenesis as a Potential Pharmacological Target.

PubMed

Scholpa, Natalie E; Schnellmann, Rick G

2017-12-01

Spinal cord injury (SCI) is characterized by an initial trauma followed by a progressive cascade of damage referred to as secondary injury. A hallmark of secondary injury is vascular disruption leading to vasoconstriction and decreased oxygen delivery, which directly reduces the ability of mitochondria to maintain homeostasis and leads to loss of ATP-dependent cellular functions, calcium overload, excitotoxicity, and oxidative stress, further exacerbating injury. Restoration of mitochondria dysfunction during the acute phases of secondary injury after SCI represents a potentially effective therapeutic strategy. This review discusses the past and present pharmacological options for the treatment of SCI as well as current research on mitochondria-targeted approaches. Increased antioxidant activity, inhibition of the mitochondrial permeability transition, alternate energy sources, and manipulation of mitochondrial morphology are among the strategies under investigation. Unfortunately, many of these tactics address single aspects of mitochondrial dysfunction, ultimately proving largely ineffective. Therefore, this review also examines the unexplored therapeutic efficacy of pharmacological enhancement of mitochondrial biogenesis, which has the potential to more comprehensively improve mitochondrial function after SCI. U.S. Government work not protected by U.S. copyright.

Tauroursodeoxycholic Acid Enhances Mitochondrial Biogenesis, Neural Stem Cell Pool, and Early Neurogenesis in Adult Rats.

PubMed

Soares, Rita; Ribeiro, Filipa F; Xapelli, Sara; Genebra, Tânia; Ribeiro, Maria F; Sebastião, Ana M; Rodrigues, Cecília M P; Solá, Susana

2018-05-01

Although neurogenesis occurs in restricted regions of the adult mammalian brain, neural stem cells (NSCs) produce very few neurons during ageing or after injury. We have recently discovered that the endogenous bile acid tauroursodeoxycholic acid (TUDCA), a strong inhibitor of mitochondrial apoptosis and a neuroprotective in animal models of neurodegenerative disorders, also enhances NSC proliferation, self-renewal, and neuronal conversion by improving mitochondrial integrity and function of NSCs. In the present study, we explore the effect of TUDCA on regulation of NSC fate in neurogenic niches, the subventricular zone (SVZ) of the lateral ventricles and the hippocampal dentate gyrus (DG), using rat postnatal neurospheres and adult rats exposed to the bile acid. TUDCA significantly induced NSC proliferation, self-renewal, and neural differentiation in the SVZ, without affecting DG-derived NSCs. More importantly, expression levels of mitochondrial biogenesis-related proteins and mitochondrial antioxidant responses were significantly increased by TUDCA in SVZ-derived NSCs. Finally, intracerebroventricular administration of TUDCA in adult rats markedly enhanced both NSC proliferation and early differentiation in SVZ regions, corroborating in vitro data. Collectively, our results highlight a potential novel role for TUDCA in neurologic disorders associated with SVZ niche deterioration and impaired neurogenesis.

Mitochondrial remodeling in adipose tissue associated with obesity and treatment with rosiglitazone

PubMed Central

Wilson-Fritch, Leanne; Nicoloro, Sarah; Chouinard, My; Lazar, Mitchell A.; Chui, Patricia C.; Leszyk, John; Straubhaar, Juerg; Czech, Michael P.; Corvera, Silvia

2004-01-01

Adipose tissue plays a central role in the control of energy homeostasis through the storage and turnover of triglycerides and through the secretion of factors that affect satiety and fuel utilization. Agents that enhance insulin sensitivity, such as rosiglitazone, appear to exert their therapeutic effect through adipose tissue, but the precise mechanisms of their actions are unclear. Rosiglitazone changes the morphological features and protein profiles of mitochondria in 3T3-L1 adipocytes. To examine the relevance of these effects in vivo, we studied white adipocytes from ob/ob mice during the development of obesity and after treatment with rosiglitazone. The levels of approximately 50% of gene transcripts encoding mitochondrial proteins were decreased with the onset of obesity. About half of those genes were upregulated after treatment with rosiglitazone, and this was accompanied by an increase in mitochondrial mass and changes in mitochondrial structure. Functionally, adipocytes from rosiglitazone-treated mice displayed markedly enhanced oxygen consumption and significantly increased palmitate oxidation. These data reveal mitochondrial remodeling and increased energy expenditure in white fat in response to rosiglitazone treatment in vivo and suggest that enhanced lipid utilization in this tissue may affect whole-body energy homeostasis and insulin sensitivity. PMID:15520860

Effects of argan oil on the mitochondrial function, antioxidant system and the activity of NADPH- generating enzymes in acrylamide treated rat brain.

PubMed

Aydın, Birsen

2017-03-01

Argan oil (AO) is rich in minor compounds such as polyphenols and tocopherols which are powerful antioxidants. Acrylamide (ACR) has been classified as a neurotoxic agent in animals and humans. Mitochondrial oxidative stress and dysfunction is one of the most probable molecular mechanisms of neurodegenerative diseases. Female Sprague Dawley rats were exposed to ACR (50mg/kg i.p. three times a week), AO (6ml/kg,o.p, per day) or together for 30days. The activities of cytosolic enzymes such as xanthine oxidase (XO), glucose 6-phosphate dehydrogenase (G6PDH), glutathione-S-transferase (GST), mitochondrial oxidative stress, oxidative phosphorylation (OXPHOS) and tricarboxylic acid cycle (TCA) enzymes, mitochondrial metabolic function, adenosine triphosphate (ATP) level and acetylcholinesterase (AChE) activity were assessed in rat brain. Cytosolic and mitochondrial antioxidant enzymes were significantly diminished in the brains of rats treated with ACR compared to those in control. Besides, ACR treatment resulted in a significant reduction in brain ATP level, mitochondrial metabolic function, OXPHOS and TCA enzymes. Administration of AO restored both the cytosolic and mitochondrial oxidative stress by normalizing nicotinamide adenine dinucleotide phosphate (NADPH) generating enzymes. In addition, improved mitochondrial function primarily enhancing nicotinamide adenine dinucleotide (NADH) generated enzymes activities and ATP level in the mitochondria. The reason for AO's obvious beneficial effects in this study may be due to synergistic effects of its different bioactive compounds which is especially effective on mitochondria. Modulation of the brain mitochondrial functions and antioxidant systems by AO may lead to the development of new mitochondria-targeted antioxidants in the future. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Cell Cycle Regulators Guide Mitochondrial Activity in Radiation-Induced Adaptive Response

PubMed Central

Alexandrou, Aris T.

2014-01-01

Abstract Significance: There are accruing concerns on potential genotoxic agents present in the environment including low-dose ionizing radiation (LDIR) that naturally exists on earth's surface and atmosphere and is frequently used in medical diagnosis and nuclear industry. Although its long-term health risk is being evaluated and remains controversial, LDIR is shown to induce temporary but significant adaptive responses in mammalian cells and animals. The mechanisms guiding the mitochondrial function in LDIR-induced adaptive response represent a unique communication between DNA damage and cellular metabolism. Elucidation of the LDIR-regulated mitochondrial activity may reveal new mechanisms adjusting cellular function to cope with hazardous environmental stress. Recent Advances: Key cell cycle regulators, including Cyclin D1/CDK4 and Cyclin B1/cyclin-dependent kinase 1 (CDK1) complexes, are actively involved in the regulation of mitochondrial functions via phosphorylation of their mitochondrial targets. Accumulating new evidence supports a concept that the Cyclin B1/CDK1 complex acts as a mediator in the cross talk between radiation-induced DNA damage and mitochondrial functions to coordinate cellular responses to low-level genotoxic stresses. Critical Issues: The LDIR-mediated mitochondrial activity via Cyclin B1/CDK1 regulation is an irreplaceable network that is able to harmonize vital cellular functions with adjusted mitochondrial metabolism to enhance cellular homeostasis. Future Directions: Further investigation of the coordinative mechanism that regulates mitochondrial activities in sublethal stress conditions, including LDIR, will reveal new insights of how cells cope with genotoxic injury and will be vital for future targeted therapeutic interventions that reduce environmental injury and cancer risk. Antioxid. Redox Signal. 20, 1463–1480. PMID:24180340

Deceleration of Fusion–Fission Cycles Improves Mitochondrial Quality Control during Aging

PubMed Central

Meyer-Hermann, Michael; Osiewacz, Heinz D.

2012-01-01

Mitochondrial dynamics and mitophagy play a key role in ensuring mitochondrial quality control. Impairment thereof was proposed to be causative to neurodegenerative diseases, diabetes, and cancer. Accumulation of mitochondrial dysfunction was further linked to aging. Here we applied a probabilistic modeling approach integrating our current knowledge on mitochondrial biology allowing us to simulate mitochondrial function and quality control during aging in silico. We demonstrate that cycles of fusion and fission and mitophagy indeed are essential for ensuring a high average quality of mitochondria, even under conditions in which random molecular damage is present. Prompted by earlier observations that mitochondrial fission itself can cause a partial drop in mitochondrial membrane potential, we tested the consequences of mitochondrial dynamics being harmful on its own. Next to directly impairing mitochondrial function, pre-existing molecular damage may be propagated and enhanced across the mitochondrial population by content mixing. In this situation, such an infection-like phenomenon impairs mitochondrial quality control progressively. However, when imposing an age-dependent deceleration of cycles of fusion and fission, we observe a delay in the loss of average quality of mitochondria. This provides a rational why fusion and fission rates are reduced during aging and why loss of a mitochondrial fission factor can extend life span in fungi. We propose the ‘mitochondrial infectious damage adaptation’ (MIDA) model according to which a deceleration of fusion–fission cycles reflects a systemic adaptation increasing life span. PMID:22761564

The effects and mechanisms of mitochondrial nutrient alpha-lipoic acid on improving age-associated mitochondrial and cognitive dysfunction: an overview.

PubMed

Liu, Jiankang

2008-01-01

We have identified a group of nutrients that can directly or indirectly protect mitochondria from oxidative damage and improve mitochondrial function and named them "mitochondrial nutrients". The direct protection includes preventing the generation of oxidants, scavenging free radicals or inhibiting oxidant reactivity, and elevating cofactors of defective mitochondrial enzymes with increased Michaelis-Menten constant to stimulate enzyme activity, and also protect enzymes from further oxidation, and the indirect protection includes repairing oxidative damage by enhancing antioxidant defense systems either through activation of phase 2 enzymes or through increase in mitochondrial biogenesis. In this review, we take alpha-lipoic acid (LA) as an example of mitochondrial nutrients by summarizing the protective effects and possible mechanisms of LA and its derivatives on age-associated cognitive and mitochondrial dysfunction of the brain. LA and its derivatives improve the age-associated decline of memory, improve mitochondrial structure and function, inhibit the age-associated increase of oxidative damage, elevate the levels of antioxidants, and restore the activity of key enzymes. In addition, co-administration of LA with other mitochondrial nutrients, such as acetyl-L: -carnitine and coenzyme Q10, appears more effective in improving cognitive dysfunction and reducing oxidative mitochondrial dysfunction. Therefore, administrating mitochondrial nutrients, such as LA and its derivatives in combination with other mitochondrial nutrients to aged people and patients suffering from neurodegenerative diseases, may be an effective strategy for improving mitochondrial and cognitive dysfunction.

Antibiotic tigecycline enhances cisplatin activity against human hepatocellular carcinoma through inducing mitochondrial dysfunction and oxidative damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Jun; Song, Meijun; Zhou, Mi

Targeting mitochondrial metabolism has been recently demonstrated to be a promising therapeutic strategy for the treatment of various cancer. In this work, we demonstrate that antibiotic tigecycline is selectively against hepatocellular carcinoma (HCC) through inducing mitochondrial dysfunction and oxidative damage. Tigecycline is more effective in inhibiting proliferation and inducing apoptosis of HCC than normal liver cells. Importantly, tigecycline significantly enhances the inhibitory effects of chemotherapeutic drug cisplatin in HCC in vitro and in vivo. Mechanistically, tigecycline specifically inhibits mitochondrial translation as shown by the decreased protein levels of Cox-1 and -2 but not Cox-4 or Grp78, and increased mRNA levels of Cox-1more » and -2 but not Cox-4 in HCC cells exposed to tigecycline. In addition, tigecycline significantly induces mitochondrial dysfunction in HCC cells via decreasing mitochondrial membrane potential, complex I and IV activities, mitochondrial respiration and ATP levels. Tigecycline also increases levels of mitochondrial superoxide, hydrogen peroxide and ROS levels. Consistent with oxidative stress, oxidative damage on DNA, protein and lipid are also observed in tigecycline-treated cells. Importantly, antioxidant N-acetyl-L-cysteine (NAC) reverses the effects of tigecycline, suggesting that oxidative stress is required for the action of tigecycline in HCC cells. We further show that HCC cells have higher level of mitochondrial biogenesis than normal liver cells which might explain the different sensitivity to tigecycline between HCC and normal liver cells. Our work is the first to demonstrate that tigecycline is a promising candidate for HCC treatment and highlight the therapeutic value of targeting mitochondrial metabolism in HCC. - Highlights: • Tigecycline selectively targets HCC in vitro and in vivo. • Tigecycline enhances HCC cell response to chemotherapeutic drug. • Tigecycline inhibits mitochondrial translation and functions in HCC cells. • Tigecycline induces oxidative stress and damage in HCC cells. • Mitochondrial biogenesis and respiration is higher in HCC than normal liver cells.« less

Deletion of PRKAA triggers mitochondrial fission by inhibiting the autophagy-dependent degradation of DNM1L.

PubMed

Wang, Qilong; Wu, Shengnan; Zhu, Huaiping; Ding, Ye; Dai, Xiaoyan; Ouyang, Changhan; Han, Young-Min; Xie, Zhonglin; Zou, Ming-Hui

2017-02-01

PRKAA (protein kinase, AMP-activated, α catalytic subunit) regulates mitochondrial biogenesis, function, and turnover. However, the molecular mechanisms by which PRKAA regulates mitochondrial dynamics remain poorly characterized. Here, we report that PRKAA regulated mitochondrial fission via the autophagy-dependent degradation of DNM1L (dynamin 1-like). Deletion of Prkaa1/AMPKα1 or Prkaa2/AMPKα2 resulted in defective autophagy, DNM1L accumulation, and aberrant mitochondrial fragmentation in the mouse aortic endothelium. Furthermore, autophagy inhibition by chloroquine treatment or ATG7 small interfering RNA (siRNA) transfection, upregulated DNM1L expression and triggered DNM1L-mediated mitochondrial fragmentation. In contrast, autophagy activation by overexpression of ATG7 or chronic administration of rapamycin, the MTOR inhibitor, promoted DNM1L degradation and attenuated mitochondrial fragmentation in Prkaa2-deficient (prkaa2 -/- ) mice, suggesting that defective autophagy contributes to enhanced DNM1L expression and mitochondrial fragmentation. Additionally, the autophagic receptor protein SQSTM1/p62, which bound to DNM1L and led to its translocation into the autophagosome, was involved in DNM1L degradation by the autophagy-lysosome pathway. Gene silencing of SQSTM1 markedly reduced the association between SQSTM1 and DNM1L, impaired the degradation of DNM1L, and enhanced mitochondrial fragmentation in PRKAA-deficient endothelial cells. Finally, the genetic (DNM1L siRNA) or pharmacological (mdivi-1) inhibition of DNMA1L ablated mitochondrial fragmentation in the mouse aortic endothelium and prevented the acetylcholine-induced relaxation of isolated mouse aortas. This suggests that aberrant DNM1L is responsible for enhanced mitochondrial fragmentation and endothelial dysfunction in prkaa knockout mice. Overall, our results show that PRKAA deletion promoted mitochondrial fragmentation in vascular endothelial cells by inhibiting the autophagy-dependent degradation of DNM1L.

Structural basis of mitochondrial dysfunction in response to cytochrome c phosphorylation at tyrosine 48

PubMed Central

Moreno-Beltrán, Blas; Guerra-Castellano, Alejandra; Del Conte, Rebecca; García-Mauriño, Sofía M.; Díaz-Moreno, Sofía; González-Arzola, Katiuska; Santos-Ocaña, Carlos; Velázquez-Campoy, Adrián; De la Rosa, Miguel A.; Turano, Paola; Díaz-Moreno, Irene

2017-01-01

Regulation of mitochondrial activity allows cells to adapt to changing conditions and to control oxidative stress, and its dysfunction can lead to hypoxia-dependent pathologies such as ischemia and cancer. Although cytochrome c phosphorylation—in particular, at tyrosine 48—is a key modulator of mitochondrial signaling, its action and molecular basis remain unknown. Here we mimic phosphorylation of cytochrome c by replacing tyrosine 48 with p-carboxy-methyl-l-phenylalanine (pCMF). The NMR structure of the resulting mutant reveals significant conformational shifts and enhanced dynamics around pCMF that could explain changes observed in its functionality: The phosphomimetic mutation impairs cytochrome c diffusion between respiratory complexes, enhances hemeprotein peroxidase and reactive oxygen species scavenging activities, and hinders caspase-dependent apoptosis. Our findings provide a framework to further investigate the modulation of mitochondrial activity by phosphorylated cytochrome c and to develop novel therapeutic approaches based on its prosurvival effects. PMID:28348229

Fluctuation-driven mechanotransduction regulates mitochondrial-network structure and function

NASA Astrophysics Data System (ADS)

Bartolák-Suki, Erzsébet; Imsirovic, Jasmin; Parameswaran, Harikrishnan; Wellman, Tyler J.; Martinez, Nuria; Allen, Philip G.; Frey, Urs; Suki, Béla

2015-10-01

Cells can be exposed to irregular mechanical fluctuations, such as those arising from changes in blood pressure. Here, we report that ATP production, assessed through changes in mitochondrial membrane potential, is downregulated in vascular smooth muscle cells in culture exposed to monotonous stretch cycles when compared with cells exposed to a variable cyclic stretch that incorporates physiological levels of cycle-by-cycle variability in stretch amplitude. Variable stretch enhances ATP production by increasing the expression of ATP synthase’s catalytic domain, cytochrome c oxidase and its tyrosine phosphorylation, mitofusins and PGC-1α. Such a fluctuation-driven mechanotransduction mechanism is mediated by motor proteins and by the enhancement of microtubule-, actin- and mitochondrial-network complexity. We also show that, in aorta rings isolated from rats, monotonous stretch downregulates--whereas variable stretch maintains--physiological vessel-wall contractility through mitochondrial ATP production. Our results have implications for ATP-dependent and mechanosensitive intracellular processes.

Nrp-1 receptor targeting peptide-functionalized TPGS micellar nanosystems to deliver 10-hydroxycampothecin for enhanced cancer chemotherapy.

PubMed

Mozhi, Anbu; Ahmad, Israr; Kaleem, Qari Muhammad; Tuguntaev, Ruslan G; Eltahan, Ahmed Shaker; Wang, Chen; Yang, Rong; Li, Chan; Liang, Xing-Jie

2018-06-01

Mitochondria are considered the power house of cells where ATP is generated for cellular metabolism, and they also act as a crucial regulator of the intrinsic apoptosis pathway. During ATP synthesis, reactive oxygen species (ROS) are produced as secondary products. Overproduction of ROS can promote mitochondrial DNA mutation, dysfunction and depolarization of the mitochondrial membrane, ultimately resulting in cell death. Therefore, the destruction of mitochondria would be an effective therapeutic approach to kill malignant tumors. Herein, we formulated a PEGylated α-TOS polymeric micellar system loaded with 10-hydroxycamptothecin (HCPT) drug to inhibit the nuclear topoisomerase I enzyme and disrupt the mitochondrial membrane to induce apoptosis. In addition, tumor-penetrating CRGDK peptide-functionalized TPGS 2k specifically bound to the Nrp-1 receptor to facilitate higher cell uptake of polymeric micelles by tumor cells. Experimental studies confirmed that HCPT-loaded and peptide-functionalized TPGS 2k -TOS micelles (HLPFTTM) showed an enhanced anti-cancer effect in A549 cancer cells. Copyright © 2018 Elsevier B.V. All rights reserved.

MIDAS/GPP34, a nuclear gene product, regulates total mitochondrial mass in response to mitochondrial dysfunction.

PubMed

Nakashima-Kamimura, Naomi; Asoh, Sadamitsu; Ishibashi, Yoshitomo; Mukai, Yuri; Shidara, Yujiro; Oda, Hideaki; Munakata, Kae; Goto, Yu-Ichi; Ohta, Shigeo

2005-11-15

To investigate the regulatory system in mitochondrial biogenesis involving crosstalk between the mitochondria and nucleus, we found a factor named MIDAS (mitochondrial DNA absence sensitive factor) whose expression was enhanced by the absence of mitochondrial DNA (mtDNA). In patients with mitochondrial diseases, MIDAS expression was increased only in dysfunctional muscle fibers. A majority of MIDAS localized to mitochondria with a small fraction in the Golgi apparatus in HeLa cells. To investigate the function of MIDAS, we stably transfected HeLa cells with an expression vector carrying MIDAS cDNA or siRNA. Cells expressing the MIDAS protein and the siRNA constitutively showed an increase and decrease in the total mass of mitochondria, respectively, accompanying the regulation of a mitochondria-specific phospholipid, cardiolipin. In contrast, amounts of the mitochondrial DNA, RNA and proteins did not depend upon MIDAS. Thus, MIDAS is involved in the regulation of mitochondrial lipids, leading to increases of total mitochondrial mass in response to mitochondrial dysfunction.

Receptor Tyrosine Kinase ErbB2 Translocates into Mitochondria and Regulates Cellular Metabolism

PubMed Central

Ding, Yan; Liu, Zixing; Desai, Shruti; Zhao, Yuhua; Liu, Hao; Pannell, Lewis K; Yi, Hong; Wright, Elizabeth R; Owen, Laurie B; Dean-Colomb, Windy; Fodstad, Oystein; Lu, Jianrong; LeDoux, Susan P; Wilson, Glenn L; Tan, Ming

2012-01-01

It is well known that ErbB2, a receptor tyrosine kinase, localizes on the plasma membrane. Here we describe a novel observation that ErbB2 also localizes in mitochondria of cancer cells and patient samples. We found that ErbB2 translocates into mitochondria through the association with mtHSP70. Additionally, mitochondrial ErbB2 (mtErbB2) negatively regulates mitochondrial respiratory functions. Oxygen consumption and activities of complexes of the mitochondrial electron transport chain were decreased in mtErbB2-overexpressing cells. Mitochondrial membrane potential and the cellular ATP level also were decreased. In contrast, mtErbB2 enhanced cellular glycolysis. The translocation of ErbB2 and its impact on mitochondrial function are kinase dependent. Interestingly, cancer cells with higher levels of mtErbB2 were more resistant to ErbB2 targeting antibody trastuzumab. Our study provides a novel perspective on the metabolic regulatory function of ErbB2 and reveals that mtErbB2 plays an important role in the regulation of cellular metabolism and cancer cell resistance to therapeutics. PMID:23232401

Protecting Mitochondrial Bioenergetic Function during Resuscitation from Cardiac Arrest

PubMed Central

Gazmuri, Raúl J.; Radhakrishnan, Jeejabai

2012-01-01

Synopsis Successful resuscitation from cardiac arrest requires reestablishment of aerobic metabolism by reperfusion with oxygenated blood of tissues that have been deprived of oxygen for variables periods of time. However, reperfusion concomitantly activates pathogenic mechanisms known as “reperfusion injury.” At the core of reperfusion injury are mitochondria, playing a critical role as effectors and targets of such injury. Mitochondrial injury compromises oxidative phosphorylation and also prompts release of cytochrome c to the cytosol and bloodstream where it correlates with severity of injury. Main drivers of such injury include Ca2+ overload and oxidative stress. Preclinical work shows that limiting myocardial cytosolic Na+ overload at the time of reperfusion attenuates mitochondrial Ca2+ overload and maintains oxidative phosphorylation yielding functional myocardial benefits that include preservation of left ventricular distensibility. Preservation of left ventricular distensibility enables hemodynamically more effective chest compression. Similar myocardial effect have been reported using erythropoietin hypothesized to protect mitochondrial bioenergetic function presumably through activation of pathways similar to those activated during preconditioning. Incorporation of novel and clinical relevant strategies to protect mitochondrial bioenergetic function are expected to attenuate injury at the time of reperfusion and enhance organ viability ultimately improving resuscitation and survival from cardiac arrest. PMID:22433486

Atorvastatin affects negatively respiratory function of isolated endothelial mitochondria.

PubMed

Broniarek, Izabela; Jarmuszkiewicz, Wieslawa

2018-01-01

The purpose of this research was to elucidate the direct effects of two popular blood cholesterol-lowering drugs used to treat cardiovascular diseases, atorvastatin and pravastatin, on respiratory function, membrane potential, and reactive oxygen species formation in mitochondria isolated from human umbilical vein endothelial cells (EA.hy926 cell line). Hydrophilic pravastatin did not significantly affect endothelial mitochondria function. In contrast, hydrophobic calcium-containing atorvastatin induced a loss of outer mitochondrial membrane integrity, an increase in hydrogen peroxide formation, and reductions in maximal (phosphorylating or uncoupled) respiratory rate, membrane potential and oxidative phosphorylation efficiency. The atorvastatin-induced changes indicate an impairment of mitochondrial function at the level of ATP synthesis and at the level of the respiratory chain, likely at complex I and complex III. The atorvastatin action on endothelial mitochondria was highly dependent on calcium ions and led to a disturbance in mitochondrial calcium homeostasis. Uptake of calcium ions included in atorvastatin molecule induced mitochondrial uncoupling that enhanced the inhibition of the mitochondrial respiratory chain by atorvastatin. Our results indicate that hydrophobic calcium-containing atorvastatin, widely used as anti-atherosclerotic agent, has a direct negative action on isolated endothelial mitochondria. Copyright © 2017. Published by Elsevier Inc.

Betaine is a positive regulator of mitochondrial respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Icksoo, E-mail: icksoolee@dankook.ac.kr

2015-01-09

Highlights: • Betaine enhances cytochrome c oxidase activity and mitochondrial respiration. • Betaine increases mitochondrial membrane potential and cellular energy levels. • Betaine’s anti-tumorigenic effect might be due to a reversal of the Warburg effect. - Abstract: Betaine protects cells from environmental stress and serves as a methyl donor in several biochemical pathways. It reduces cardiovascular disease risk and protects liver cells from alcoholic liver damage and nonalcoholic steatohepatitis. Its pretreatment can rescue cells exposed to toxins such as rotenone, chloroform, and LiCl. Furthermore, it has been suggested that betaine can suppress cancer cell growth in vivo and in vitro.more » Mitochondrial electron transport chain (ETC) complexes generate the mitochondrial membrane potential, which is essential to produce cellular energy, ATP. Reduced mitochondrial respiration and energy status have been found in many human pathological conditions including aging, cancer, and neurodegenerative disease. In this study we investigated whether betaine directly targets mitochondria. We show that betaine treatment leads to an upregulation of mitochondrial respiration and cytochrome c oxidase activity in H2.35 cells, the proposed rate limiting enzyme of ETC in vivo. Following treatment, the mitochondrial membrane potential was increased and cellular energy levels were elevated. We propose that the anti-proliferative effects of betaine on cancer cells might be due to enhanced mitochondrial function contributing to a reversal of the Warburg effect.« less

VALSARTAN REGULATES MYOCARDIAL AUTOPHAGY AND MITOCHONDRIAL TURNOVER IN EXPERIMENTAL HYPERTENSION

PubMed Central

Zhang, Xin; Li, Zi-Lun; Crane, John A.; Jordan, Kyra L.; Pawar, Aditya S.; Textor, Stephen C.; Lerman, Amir; Lerman, Lilach O.

2014-01-01

Renovascular hypertension alters cardiac structure and function. Autophagy is activated during left ventricular hypertrophy and linked to adverse cardiac function. The Angiotensin II receptor blocker Valsartan lowers blood pressure and is cardioprotective, but whether it modulates autophagy in the myocardium is unclear. We hypothesized that Valsartan would alleviate autophagy and improve left ventricular myocardial mitochondrial turnover in swine renovascular hypertension. Domestic pigs were randomized to control, unilateral renovascular hypertension, and renovascular hypertension treated with Valsartan (320 mg/day) or conventional triple therapy (Reserpine+hydralazine+hydrochlorothiazide) for 4 weeks post 6-weeks of renovascular hypertension (n=7 each group). Left ventricular remodeling, function and myocardial oxygenation and microcirculation were assessed by multi-detector computer tomography, blood-oxygen-level-dependent magnetic resonance imaging and microcomputer tomography. Myocardial autophagy, markers for mitochondrial degradation and biogenesis, and mitochondrial respiratory-chain proteins were examined ex vivo. Renovascular hypertension induced left ventricular hypertrophy and myocardial hypoxia, enhanced cellular autophagy and mitochondrial degradation, and suppressed mitochondrial biogenesis. Valsartan and triple therapy similarly decreased blood pressure, but Valsartan solely alleviated left ventricular hypertrophy, ameliorated myocardial autophagy and mitophagy, and increased mitochondrial biogenesis. In contrast, triple therapy only slightly attenuated autophagy and preserved mitochondrial proteins, but elicited no improvement in mitophagy. These data suggest a novel potential role of Valsartan in modulating myocardial autophagy and mitochondrial turnover in renovascular hypertension-induced hypertensive heart disease, which may possibly bolster cardiac repair via a blood pressure-independent manner. PMID:24752430

Hyperoxia activates ATM independent from mitochondrial ROS and dysfunction.

PubMed

Resseguie, Emily A; Staversky, Rhonda J; Brookes, Paul S; O'Reilly, Michael A

2015-08-01

High levels of oxygen (hyperoxia) are often used to treat individuals with respiratory distress, yet prolonged hyperoxia causes mitochondrial dysfunction and excessive reactive oxygen species (ROS) that can damage molecules such as DNA. Ataxia telangiectasia mutated (ATM) kinase is activated by nuclear DNA double strand breaks and delays hyperoxia-induced cell death through downstream targets p53 and p21. Evidence for its role in regulating mitochondrial function is emerging, yet it has not been determined if mitochondrial dysfunction or ROS activates ATM. Because ATM maintains mitochondrial homeostasis, we hypothesized that hyperoxia induces both mitochondrial dysfunction and ROS that activate ATM. In A549 lung epithelial cells, hyperoxia decreased mitochondrial respiratory reserve capacity at 12h and basal respiration by 48 h. ROS were significantly increased at 24h, yet mitochondrial DNA double strand breaks were not detected. ATM was not required for activating p53 when mitochondrial respiration was inhibited by chronic exposure to antimycin A. Also, ATM was not further activated by mitochondrial ROS, which were enhanced by depleting manganese superoxide dismutase (SOD2). In contrast, ATM dampened the accumulation of mitochondrial ROS during exposure to hyperoxia. Our findings suggest that hyperoxia-induced mitochondrial dysfunction and ROS do not activate ATM. ATM more likely carries out its canonical response to nuclear DNA damage and may function to attenuate mitochondrial ROS that contribute to oxygen toxicity. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Pathological presentation of cardiac mitochondria in a rat model for chronic kidney disease.

PubMed

Bigelman, Einat; Cohen, Lena; Aharon-Hananel, Genya; Levy, Ran; Rozenbaum, Zach; Saada, Ann; Keren, Gad; Entin-Meer, Michal

2018-01-01

Mitochondria hold crucial importance in organs with high energy demand especially the heart. We investigated whether chronic kidney disease (CKD), which eventually culminates in cardiorenal syndrome, could affect cardiac mitochondria and assessed the potential involvement of angiotensin II (AngII) in the process. Male Lewis rats underwent 5/6 nephrectomy allowing CKD development for eight months or for eleven weeks. Short-term CKD rats were administered with AngII receptor blocker (ARB). Cardiac function was assessed by echocardiography and cardiac sections were evaluated for interstitial fibrosis and cardiomyocytes' hypertrophy. Electron microscopy was used to explore the spatial organization of the cardiomyocytes. Expression levels of mitochondrial content and activity markers were tested in order to delineate the underlying mechanisms for mitochondrial pathology in the CKD setting with or without ARB administration. CKD per-se resulted in induced cardiac interstitial fibrosis and cardiomyocytes' hypertrophy combined with a marked disruption of the mitochondrial structure. Moreover, CKD led to enhanced cytochrome C leakage to the cytosol and to enhanced PARP-1 cleavage which are associated with cellular apoptosis. ARB treatment did not improve kidney function but markedly reduced left ventricular mass, cardiomyocytes' hypertrophy and interstitial fibrosis. Interestingly, ARB administration improved the spatial organization of cardiac mitochondria and reduced their increased volume compared to untreated CKD animals. Nevertheless, ARB did not improve mitochondrial content, mitochondrial biogenesis or the respiratory enzyme activity. ARB mildly upregulated protein levels of mitochondrial fusion-related proteins. CKD results in cardiac pathological changes combined with mitochondrial damage and elevated apoptotic markers. We anticipate that the increased mitochondrial volume mainly represents mitochondrial swelling that occurs during the pathological process of cardiac hypertrophy. Chronic administration of ARB may improve the pathological appearance of the heart. Further recognition of the molecular pathways leading to mitochondrial insult and appropriate intervention is of crucial importance.

Improved mitochondrial function underlies the protective effect of pirfenidone against tubulointerstitial fibrosis in 5/6 nephrectomized rats.

PubMed

Chen, Jun-Feng; Liu, Hong; Ni, Hai-Feng; Lv, Lin-Li; Zhang, Ming-Hui; Zhang, Ai-Hua; Tang, Ri-Ning; Chen, Ping-Sheng; Liu, Bi-Cheng

2013-01-01

Dysfunctional mitochondria participate in the progression of chronic kidney disease (CKD). Pirfenidone is a newly identified anti-fibrotic drug. However, its mechanism remains unclear. Mitochondrial dysfunction is an early event that occurs prior to the onset of renal fibrosis. In this context, we investigated the protective effect of pirfenidone on mitochondria and its relevance to apoptosis and oxidative stress in renal proximal tubular cells. A remnant kidney rat model was established. Human renal proximal tubular epithelial cells (HK2) using rotenone, a mitochondrial respiratory chain complex Ι inhibitor were further investigated in vitro to examine the mitochondrial protective effect of pirfenidone. Pirfenidone protected mitochondrial structures and functions by stabilizing the mitochondrial membrane potential, maintaining ATP production and improving the mitochondrial DNA (mtDNA) copy number. Pirfenidone decreased tubular cell apoptosis by inhibiting the mitochondrial apoptotic signaling pathway. Pirfenidone also reduced oxidative stress by enhancing manganese superoxide dismutase (Mn-SOD) and inhibiting intracellular reactive oxygen species (ROS) generation, which suggested that the anti-oxidant effects occurred at least partially via the mitochondrial pathway. Pirfenidone may be effective prior to the onset of renal fibrosis because this drug exerts its anti-fibrotic effect by protection of mitochondria in renal proximal tubular cells.

Improved Mitochondrial Function Underlies the Protective Effect of Pirfenidone against Tubulointerstitial Fibrosis in 5/6 Nephrectomized Rats

PubMed Central

Chen, Jun-Feng; Liu, Hong; Ni, Hai-Feng; Lv, Lin-Li; Zhang, Ming-Hui; Zhang, Ai-Hua; Tang, Ri-Ning; Chen, Ping-Sheng; Liu, Bi-Cheng

2013-01-01

Dysfunctional mitochondria participate in the progression of chronic kidney disease (CKD). Pirfenidone is a newly identified anti-fibrotic drug. However, its mechanism remains unclear. Mitochondrial dysfunction is an early event that occurs prior to the onset of renal fibrosis. In this context, we investigated the protective effect of pirfenidone on mitochondria and its relevance to apoptosis and oxidative stress in renal proximal tubular cells. A remnant kidney rat model was established. Human renal proximal tubular epithelial cells (HK2) using rotenone, a mitochondrial respiratory chain complex Ι inhibitor were further investigated in vitro to examine the mitochondrial protective effect of pirfenidone. Pirfenidone protected mitochondrial structures and functions by stabilizing the mitochondrial membrane potential, maintaining ATP production and improving the mitochondrial DNA (mtDNA) copy number. Pirfenidone decreased tubular cell apoptosis by inhibiting the mitochondrial apoptotic signaling pathway. Pirfenidone also reduced oxidative stress by enhancing manganese superoxide dismutase (Mn-SOD) and inhibiting intracellular reactive oxygen species (ROS) generation, which suggested that the anti-oxidant effects occurred at least partially via the mitochondrial pathway. Pirfenidone may be effective prior to the onset of renal fibrosis because this drug exerts its anti-fibrotic effect by protection of mitochondria in renal proximal tubular cells. PMID:24349535

Exercise Promotes Healthy Aging of Skeletal Muscle.

PubMed

Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M; Zierath, Juleen R

2016-06-14

Primary aging is the progressive and inevitable process of bodily deterioration during adulthood. In skeletal muscle, primary aging causes defective mitochondrial energetics and reduced muscle mass. Secondary aging refers to additional deleterious structural and functional age-related changes caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle. Copyright © 2016 Elsevier Inc. All rights reserved.

Ionizing radiation induces mitochondrial reactive oxygen species production accompanied by upregulation of mitochondrial electron transport chain function and mitochondrial content under control of the cell cycle checkpoint.

PubMed

Yamamori, Tohru; Yasui, Hironobu; Yamazumi, Masayuki; Wada, Yusuke; Nakamura, Yoshinari; Nakamura, Hideo; Inanami, Osamu

2012-07-15

Whereas ionizing radiation (Ir) instantaneously causes the formation of water radiolysis products that contain some reactive oxygen species (ROS), ROS are also suggested to be released from biological sources in irradiated cells. It is now becoming clear that these ROS generated secondarily after Ir have a variety of biological roles. Although mitochondria are assumed to be responsible for this Ir-induced ROS production, it remains to be elucidated how Ir triggers it. Therefore, we conducted this study to decipher the mechanism of Ir-induced mitochondrial ROS production. In human lung carcinoma A549 cells, Ir (10 Gy of X-rays) induced a time-dependent increase in the mitochondrial ROS level. Ir also increased mitochondrial membrane potential, mitochondrial respiration, and mitochondrial ATP production, suggesting upregulation of the mitochondrial electron transport chain (ETC) function after Ir. Although we found that Ir slightly enhanced mitochondrial ETC complex II activity, the complex II inhibitor 3-nitropropionic acid failed to reduce Ir-induced mitochondrial ROS production. Meanwhile, we observed that the mitochondrial mass and mitochondrial DNA level were upregulated after Ir, indicating that Ir increased the mitochondrial content of the cell. Because irradiated cells are known to undergo cell cycle arrest under control of the checkpoint mechanisms, we examined the relationships between cell cycle and mitochondrial content and cellular oxidative stress level. We found that the cells in the G2/M phase had a higher mitochondrial content and cellular oxidative stress level than cells in the G1 or S phase, regardless of whether the cells were irradiated. We also found that Ir-induced accumulation of the cells in the G2/M phase led to an increase in cells with a high mitochondrial content and cellular oxidative stress level. This suggested that Ir upregulated mitochondrial ETC function and mitochondrial content, resulting in mitochondrial ROS production, and that Ir-induced G2/M arrest contributed to the increase in the mitochondrial ROS level by accumulating cells in the G2/M phase. Copyright © 2012 Elsevier Inc. All rights reserved.

Alcohol dehydrogenase accentuates ethanol-induced myocardial dysfunction and mitochondrial damage in mice: role of mitochondrial death pathway.

PubMed

Guo, Rui; Ren, Jun

2010-01-18

Binge drinking and alcohol toxicity are often associated with myocardial dysfunction possibly due to accumulation of the ethanol metabolite acetaldehyde although the underlying mechanism is unknown. This study was designed to examine the impact of accelerated ethanol metabolism on myocardial contractility, mitochondrial function and apoptosis using a murine model of cardiac-specific overexpression of alcohol dehydrogenase (ADH). ADH and wild-type FVB mice were acutely challenged with ethanol (3 g/kg/d, i.p.) for 3 days. Myocardial contractility, mitochondrial damage and apoptosis (death receptor and mitochondrial pathways) were examined. Ethanol led to reduced cardiac contractility, enlarged cardiomyocyte, mitochondrial damage and apoptosis, the effects of which were exaggerated by ADH transgene. In particular, ADH exacerbated mitochondrial dysfunction manifested as decreased mitochondrial membrane potential and accumulation of mitochondrial O(2) (*-). Myocardium from ethanol-treated mice displayed enhanced Bax, Caspase-3 and decreased Bcl-2 expression, the effect of which with the exception of Caspase-3 was augmented by ADH. ADH accentuated ethanol-induced increase in the mitochondrial death domain components pro-caspase-9 and cytochrome C in the cytoplasm. Neither ethanol nor ADH affected the expression of ANP, total pro-caspase-9, cytosolic and total pro-caspase-8, TNF-alpha, Fas receptor, Fas L and cytosolic AIF. Taken together, these data suggest that enhanced acetaldehyde production through ADH overexpression following acute ethanol exposure exacerbated ethanol-induced myocardial contractile dysfunction, cardiomyocyte enlargement, mitochondrial damage and apoptosis, indicating a pivotal role of ADH in ethanol-induced cardiac dysfunction possibly through mitochondrial death pathway of apoptosis.

Mitochondrial DNA Damage and Diseases.

PubMed

Singh, Gyanesh; Pachouri, U C; Khaidem, Devika Chanu; Kundu, Aman; Chopra, Chirag; Singh, Pushplata

2015-01-01

Various endogenous and environmental factors can cause mitochondrial DNA (mtDNA) damage.  One of the reasons for enhanced mtDNA damage could be its proximity to the source of oxidants, and lack of histone-like protective proteins. Moreover, mitochondria contain inadequate DNA repair pathways, and, diminished DNA repair capacity may be one of the factors responsible for high mutation frequency of the mtDNA. mtDNA damage might cause impaired mitochondrial function, and, unrepaired mtDNA damage has been frequently linked with several diseases. Exploration of mitochondrial perspective of diseases might lead to a better understanding of several diseases, and will certainly open new avenues for detection, cure, and prevention of ailments.

FOXO3a regulates BNIP3 and modulates mitochondrial calcium, dynamics, and function in cardiac stress

PubMed Central

Kohlbrenner, Erik; Gamb, Scott I.; Guenzel, Adam J.; Klaus, Katherine; Fayyaz, Ahmed U.; Nair, K. Sreekumaran; Hajjar, Roger J.

2016-01-01

The forkhead box O3a (FOXO3a) transcription factor has been shown to regulate glucose metabolism, muscle atrophy, and cell death in postmitotic cells. Its role in regulation of mitochondrial and myocardial function is not well studied. Based on previous work, we hypothesized that FOXO3a, through BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (BNIP3), modulates mitochondrial morphology and function in heart failure (HF). We modulated the FOXO3a-BNIP3 pathway in normal and phenylephrine (PE)-stressed adult cardiomyocytes (ACM) in vitro and developed a cardiotropic adeno-associated virus serotype 9 encoding dominant-negative FOXO3a (AAV9.dn-FX3a) for gene delivery in a rat model of HF with preserved ejection fraction (HFpEF). We found that FOXO3a upregulates BNIP3 expression in normal and PE-stressed ACM, with subsequent increases in mitochondrial Ca2+, leading to decreased mitochondrial membrane potential, mitochondrial fragmentation, and apoptosis. Whereas dn-FX3a attenuated the increase in BNIP3 expression and its consequences in PE-stressed ACM, AAV9.dn-FX3a delivery in an experimental model of HFpEF decreased BNIP3 expression, reversed adverse left ventricular remodeling, and improved left ventricular systolic and, particularly, diastolic function, with improvements in mitochondrial structure and function. Moreover, AAV9.dn-FX3a restored phospholamban phosphorylation at S16 and enhanced dynamin-related protein 1 phosphorylation at S637. Furthermore, FOXO3a upregulates maladaptive genes involved in mitochondrial apoptosis, autophagy, and cardiac atrophy. We conclude that FOXO3a activation in cardiac stress is maladaptive, in that it modulates Ca2+ cycling, Ca2+ homeostasis, and mitochondrial dynamics and function. Our results suggest an important role of FOXO3a in HF, making it an attractive potential therapeutic target. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/role-of-foxo3a-in-heart-failure/. PMID:27694219

Oxidative stress-induced mitochondrial dysfunction drives inflammation and airway smooth muscle remodeling in patients with chronic obstructive pulmonary disease.

PubMed

Wiegman, Coen H; Michaeloudes, Charalambos; Haji, Gulammehdi; Narang, Priyanka; Clarke, Colin J; Russell, Kirsty E; Bao, Wuping; Pavlidis, Stelios; Barnes, Peter J; Kanerva, Justin; Bittner, Anton; Rao, Navin; Murphy, Michael P; Kirkham, Paul A; Chung, Kian Fan; Adcock, Ian M

2015-09-01

Inflammation and oxidative stress play critical roles in patients with chronic obstructive pulmonary disease (COPD). Mitochondrial oxidative stress might be involved in driving the oxidative stress-induced pathology. We sought to determine the effects of oxidative stress on mitochondrial function in the pathophysiology of airway inflammation in ozone-exposed mice and human airway smooth muscle (ASM) cells. Mice were exposed to ozone, and lung inflammation, airway hyperresponsiveness (AHR), and mitochondrial function were determined. Human ASM cells were isolated from bronchial biopsy specimens from healthy subjects, smokers, and patients with COPD. Inflammation and mitochondrial function in mice and human ASM cells were measured with and without the presence of the mitochondria-targeted antioxidant MitoQ. Mice exposed to ozone, a source of oxidative stress, had lung inflammation and AHR associated with mitochondrial dysfunction and reflected by decreased mitochondrial membrane potential (ΔΨm), increased mitochondrial oxidative stress, and reduced mitochondrial complex I, III, and V expression. Reversal of mitochondrial dysfunction by the mitochondria-targeted antioxidant MitoQ reduced inflammation and AHR. ASM cells from patients with COPD have reduced ΔΨm, adenosine triphosphate content, complex expression, basal and maximum respiration levels, and respiratory reserve capacity compared with those from healthy control subjects, whereas mitochondrial reactive oxygen species (ROS) levels were increased. Healthy smokers were intermediate between healthy nonsmokers and patients with COPD. Hydrogen peroxide induced mitochondrial dysfunction in ASM cells from healthy subjects. MitoQ and Tiron inhibited TGF-β-induced ASM cell proliferation and CXCL8 release. Mitochondrial dysfunction in patients with COPD is associated with excessive mitochondrial ROS levels, which contribute to enhanced inflammation and cell hyperproliferation. Targeting mitochondrial ROS represents a promising therapeutic approach in patients with COPD. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Citral exerts its antifungal activity against Penicillium digitatum by affecting the mitochondrial morphology and function.

PubMed

Zheng, Shiju; Jing, Guoxing; Wang, Xiao; Ouyang, Qiuli; Jia, Lei; Tao, Nengguo

2015-07-01

This work investigated the effect of citral on the mitochondrial morphology and function of Penicillium digitatum. Citral at concentrations of 2.0 or 4.0 μL/mL strongly damaged mitochondria of test pathogen by causing the loss of matrix and increase of irregular mitochondria. The deformation extent of the mitochondria of P. digitatum enhanced with increasing concentrations of citral, as evidenced by a decrease in intracellular ATP content and an increase in extracellular ATP content of P. digitatum cells. Oxygen consumption showed that citral resulted in an inhibition in the tricarboxylic acid cycle (TCA) pathway of P. digitatum cells, induced a decrease in activities of citrate synthetase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinodehydrogenase and the content of citric acid, while enhancing the activity of malic dehydrogenase in P. digitatum cells. Our present results indicated that citral could damage the mitochondrial membrane permeability and disrupt the TCA pathway of P. digitatum. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mitochondrial Transfer from Wharton's Jelly Mesenchymal Stem Cell to MERRF Cybrid Reduces Oxidative Stress and Improves Mitochondrial Bioenergetics

PubMed Central

Liou, Chia-Wei; Chen, Shang-Der; Wang, Pei-Wen; Chuang, Jiin-Haur; Tiao, Mao-Meng; Hsu, Te-Yao

2017-01-01

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a maternally inherited mitochondrial disease affecting neuromuscular functions. Mt.8344A>G mutation in mitochondrial DNA (mtDNA) is the most common cause of MERRF syndrome and has been linked to an increase in reactive oxygen species (ROS) level and oxidative stress, as well as impaired mitochondrial bioenergetics. Here, we tested whether WJMSC has therapeutic potential for the treatment of MERRF syndrome through the transfer of mitochondria. The MERRF cybrid cells exhibited a high mt.8344A>G mutation ratio, enhanced ROS level and oxidative damage, impaired mitochondrial bioenergetics, defected mitochondria-dependent viability, exhibited an imbalance of mitochondrial dynamics, and are susceptible to apoptotic stress. Coculture experiments revealed that mitochondria were intercellularly conducted from the WJMSC to the MERRF cybrid. Furthermore, WJMSC transferred mitochondria exclusively to cells with defective mitochondria but not to cells with normal mitochondria. MERRF cybrid following WJMSC coculture (MF+WJ) demonstrated improvement of mt.8344A>G mutation ratio, ROS level, oxidative damage, mitochondrial bioenergetics, mitochondria-dependent viability, balance of mitochondrial dynamics, and resistance against apoptotic stress. WJMSC-derived mitochondrial transfer and its therapeutic effect were noted to be blocked by F-actin depolymerizing agent cytochalasin B. Collectively, the WJMSC ability to rescue cells with defective mitochondrial function through donating healthy mitochondria may lead to new insights into the development of more efficient strategies to treat diseases related to mitochondrial dysfunction. PMID:28607632

Late Administration of a Palladium Lipoic Acid Complex (POLY-MVA) Modifies Cardiac Mitochondria but Not Functional or Structural Manifestations of Radiation-Induced Heart Disease in a Rat Model

PubMed Central

Sridharan, Vijayalakshmi; Seawright, John W.; Antonawich, Francis J.; Garnett, Merrill; Cao, Maohua; Singh, Preeti; Boerma, Marjan

2017-01-01

Exposure of the heart to ionizing radiation can cause adverse myocardial remodeling. In small animal models, local heart irradiation causes persistent alterations in cardiac mitochondrial function and swelling. POLY-MVA is a dietary supplement that contains a palladium lipoic acid complex that targets mitochondrial complex I and has been demonstrated to have greater redox potential than lipoic acid alone. POLY-MVA improves mitochondrial function and anti-oxidant enzyme activity in the aged rat heart. In this study, we tested whether POLY-MVA can mitigate cardiac effects of ionizing radiation. Adult male rats were exposed to local heart X rays with a daily dose of 9 Gy for 5 consecutive days. Eighteen weeks after irradiation, POLY-MVA was administered orally at 1 ml/kg bodyweight per day during weekdays, for 6 weeks. Alterations in cardiac function as measured with echocardiography coincided with enhanced mitochondrial swelling, a reduction in mitochondrial expression of complex II, manifestations of adverse remodeling such as a reduction in myocardial microvessel density and an increase in collagen deposition and mast cell numbers. POLY-MVA enhanced left ventricular expression of superoxide dismutase 2, but only in sham-irradiated animals. In irradiated animals, POLY-MVA caused a reduction in markers of inflammatory infiltration, CD2 and CD68. Moreover, POLY-MVA mitigated the effects of radiation on mitochondria. Nonetheless, POLY-MVA did not mitigate adverse cardiac remodeling, suggesting that this tissue remodeling may not be alleviated by altering cardiac mitochondria alone. However, we cannot exclude the possibility that an earlier onset of POLY-MVA administration may have more profound effects on radiation-induced cardiac remodeling. PMID:28231026

Control mechanisms in mitochondrial oxidative phosphorylation☆

PubMed Central

Hroudová, Jana; Fišar, Zdeněk

2013-01-01

Distribution and activity of mitochondria are key factors in neuronal development, synaptic plasticity and axogenesis. The majority of energy sources, necessary for cellular functions, originate from oxidative phosphorylation located in the inner mitochondrial membrane. The adenosine-5’- triphosphate production is regulated by many control mechanism–firstly by oxygen, substrate level, adenosine-5’-diphosphate level, mitochondrial membrane potential, and rate of coupling and proton leak. Recently, these mechanisms have been implemented by “second control mechanisms,” such as reversible phosphorylation of the tricarboxylic acid cycle enzymes and electron transport chain complexes, allosteric inhibition of cytochrome c oxidase, thyroid hormones, effects of fatty acids and uncoupling proteins. Impaired function of mitochondria is implicated in many diseases ranging from mitochondrial myopathies to bipolar disorder and schizophrenia. Mitochondrial dysfunctions are usually related to the ability of mitochondria to generate adenosine-5’-triphosphate in response to energy demands. Large amounts of reactive oxygen species are released by defective mitochondria, similarly, decline of antioxidative enzyme activities (e.g. in the elderly) enhances reactive oxygen species production. We reviewed data concerning neuroplasticity, physiology, and control of mitochondrial oxidative phosphorylation and reactive oxygen species production. PMID:25206677

Control mechanisms in mitochondrial oxidative phosphorylation.

PubMed

Hroudová, Jana; Fišar, Zdeněk

2013-02-05

Distribution and activity of mitochondria are key factors in neuronal development, synaptic plasticity and axogenesis. The majority of energy sources, necessary for cellular functions, originate from oxidative phosphorylation located in the inner mitochondrial membrane. The adenosine-5'- triphosphate production is regulated by many control mechanism-firstly by oxygen, substrate level, adenosine-5'-diphosphate level, mitochondrial membrane potential, and rate of coupling and proton leak. Recently, these mechanisms have been implemented by "second control mechanisms," such as reversible phosphorylation of the tricarboxylic acid cycle enzymes and electron transport chain complexes, allosteric inhibition of cytochrome c oxidase, thyroid hormones, effects of fatty acids and uncoupling proteins. Impaired function of mitochondria is implicated in many diseases ranging from mitochondrial myopathies to bipolar disorder and schizophrenia. Mitochondrial dysfunctions are usually related to the ability of mitochondria to generate adenosine-5'-triphosphate in response to energy demands. Large amounts of reactive oxygen species are released by defective mitochondria, similarly, decline of antioxidative enzyme activities (e.g. in the elderly) enhances reactive oxygen species production. We reviewed data concerning neuroplasticity, physiology, and control of mitochondrial oxidative phosphorylation and reactive oxygen species production.

Distinct Mechanisms of Pathogenic DJ-1 Mutations in Mitochondrial Quality Control

PubMed Central

Strobbe, Daniela; Robinson, Alexis A.; Harvey, Kirsten; Rossi, Lara; Ferraina, Caterina; de Biase, Valerio; Rodolfo, Carlo; Harvey, Robert J.; Campanella, Michelangelo

2018-01-01

The deglycase and chaperone protein DJ-1 is pivotal for cellular oxidative stress responses and mitochondrial quality control. Mutations in PARK7, encoding DJ-1, are associated with early-onset familial Parkinson’s disease and lead to pathological oxidative stress and/or disrupted protein degradation by the proteasome. The aim of this study was to gain insights into the pathogenic mechanisms of selected DJ-1 missense mutations, by characterizing protein–protein interactions, core parameters of mitochondrial function, quality control regulation via autophagy, and cellular death following dopamine accumulation. We report that the DJ-1M26I mutant influences DJ-1 interactions with SUMO-1, in turn enhancing removal of mitochondria and conferring increased cellular susceptibility to dopamine toxicity. By contrast, the DJ-1D149A mutant does not influence mitophagy, but instead impairs Ca2+ dynamics and free radical homeostasis by disrupting DJ-1 interactions with a mitochondrial accessory protein known as DJ-1-binding protein (DJBP/EFCAB6). Thus, individual DJ-1 mutations have different effects on mitochondrial function and quality control, implying mutation-specific pathomechanisms converging on impaired mitochondrial homeostasis. PMID:29599708

Erythropoietin activates SIRT1 to protect human cardiomyocytes against doxorubicin-induced mitochondrial dysfunction and toxicity.

PubMed

Cui, Lan; Guo, Jiabin; Zhang, Qiang; Yin, Jian; Li, Jin; Zhou, Wei; Zhang, Tingfen; Yuan, Haitao; Zhao, Jun; Zhang, Li; Carmichael, Paul L; Peng, Shuangqing

2017-06-05

The hormone erythropoietin (EPO) has been demonstrated to protect against chemotherapy drug doxorubicin (DOX)-induced cardiotoxicity, but the underlying mechanism remains obscure. We hypothesized that silent mating type information regulation 2 homolog 1 (SIRT1), an NAD + -dependent protein deacetylase that activates peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), plays a crucial role in regulating mitochondrial function and mediating the beneficial effect of EPO. Our study in human cardiomyocyte AC16 cells showed that DOX-induced cytotoxicity and mitochondrial dysfunction, as manifested by decreased mitochondrial DNA (mtDNA) copy number, mitochondrial membrane potential, and increased mitochondrial superoxide accumulation, can be mitigated by EPO pretreatment. EPO was found to upregulate SIRT1 activity and protein expression to reverse DOX-induced acetylation of PGC-1α and suppression of a suite of PGC-1α-activated genes involved in mitochondrial function and biogenesis, such as nuclear respiratory factor-1 (NRF1), mitochondrial transcription factor A (TFAM), citrate synthase (CS), superoxide dismutase 2 (SOD2), cytochrome c oxidase IV (COXIV), and voltage-dependent anion channel (VDAC). Silencing of SIRT1 via small RNA interference sensitized AC16 cells to DOX-induced cytotoxicity and reduction in mtDNA copy number. Although with SIRT1 silenced, EPO could reverse to some extent DOX-induced mitochondrial superoxide accumulation, loss of mitochondrial membrane potential and ATP depletion, it failed to normalize protein expression of PGC-1α and its downstream genes. Taken together, our results indicated that EPO may activate SIRT1 to enhance mitochondrial function and protect against DOX-induced cardiotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Chronic plus binge ethanol feeding induces myocardial oxidative stress, mitochondrial and cardiovascular dysfunction, and steatosis

PubMed Central

Matyas, Csaba; Varga, Zoltan V.; Mukhopadhyay, Partha; Paloczi, Janos; Lajtos, Tamas; Erdelyi, Katalin; Nemeth, Balazs T.; Nan, Mintong; Hasko, Gyorgy; Gao, Bin

2016-01-01

Alcoholic cardiomyopathy in humans develops in response to chronic excessive alcohol consumption; however, good models of alcohol-induced cardiomyopathy in mice are lacking. Herein we describe mouse models of alcoholic cardiomyopathies induced by chronic and binge ethanol (EtOH) feeding and characterize detailed hemodynamic alterations, mitochondrial function, and redox signaling in these models. Mice were fed a liquid diet containing 5% EtOH for 10, 20, and 40 days (d) combined with single or multiple EtOH binges (5 g/kg body wt). Isocalorically pair-fed mice served as controls. Left ventricular (LV) function and morphology were assessed by invasive pressure-volume conductance approach and by echocardiography. Mitochondrial complex (I, II, IV) activities, 3-nitrotyrosine (3-NT) levels, gene expression of markers of oxidative stress (gp91phox, p47phox), mitochondrial biogenesis (PGC1α, peroxisome proliferator-activated receptor α), and fibrosis were examined. Cardiac steatosis and fibrosis were investigated by histological/immunohistochemical methods. Chronic and binge EtOH feeding (already in 10 days EtOH plus single binge group) was characterized by contractile dysfunction (decreased slope of end-systolic pressure-volume relationship and preload recruitable stroke work), impaired relaxation (decreased time constant of LV pressure decay and maximal slope of systolic pressure decrement), and vascular dysfunction (impaired arterial elastance and lower total peripheral resistance). This was accompanied by enhanced myocardial oxidative/nitrative stress (3-NT; gp91phox; p47phox; angiotensin II receptor, type 1a) and deterioration of mitochondrial complex I, II, IV activities and mitochondrial biogenesis, excessive cardiac steatosis, and higher mortality. Collectively, chronic plus binge EtOH feeding in mice leads to alcohol-induced cardiomyopathies (National Institute on Alcohol Abuse and Alcoholism models) characterized by increased myocardial oxidative/nitrative stress, impaired mitochondrial function and biogenesis, and enhanced cardiac steatosis. PMID:27106042

Chronic plus binge ethanol feeding induces myocardial oxidative stress, mitochondrial and cardiovascular dysfunction, and steatosis.

PubMed

Matyas, Csaba; Varga, Zoltan V; Mukhopadhyay, Partha; Paloczi, Janos; Lajtos, Tamas; Erdelyi, Katalin; Nemeth, Balazs T; Nan, Mintong; Hasko, Gyorgy; Gao, Bin; Pacher, Pal

2016-06-01

Alcoholic cardiomyopathy in humans develops in response to chronic excessive alcohol consumption; however, good models of alcohol-induced cardiomyopathy in mice are lacking. Herein we describe mouse models of alcoholic cardiomyopathies induced by chronic and binge ethanol (EtOH) feeding and characterize detailed hemodynamic alterations, mitochondrial function, and redox signaling in these models. Mice were fed a liquid diet containing 5% EtOH for 10, 20, and 40 days (d) combined with single or multiple EtOH binges (5 g/kg body wt). Isocalorically pair-fed mice served as controls. Left ventricular (LV) function and morphology were assessed by invasive pressure-volume conductance approach and by echocardiography. Mitochondrial complex (I, II, IV) activities, 3-nitrotyrosine (3-NT) levels, gene expression of markers of oxidative stress (gp91phox, p47phox), mitochondrial biogenesis (PGC1α, peroxisome proliferator-activated receptor α), and fibrosis were examined. Cardiac steatosis and fibrosis were investigated by histological/immunohistochemical methods. Chronic and binge EtOH feeding (already in 10 days EtOH plus single binge group) was characterized by contractile dysfunction (decreased slope of end-systolic pressure-volume relationship and preload recruitable stroke work), impaired relaxation (decreased time constant of LV pressure decay and maximal slope of systolic pressure decrement), and vascular dysfunction (impaired arterial elastance and lower total peripheral resistance). This was accompanied by enhanced myocardial oxidative/nitrative stress (3-NT; gp91phox; p47phox; angiotensin II receptor, type 1a) and deterioration of mitochondrial complex I, II, IV activities and mitochondrial biogenesis, excessive cardiac steatosis, and higher mortality. Collectively, chronic plus binge EtOH feeding in mice leads to alcohol-induced cardiomyopathies (National Institute on Alcohol Abuse and Alcoholism models) characterized by increased myocardial oxidative/nitrative stress, impaired mitochondrial function and biogenesis, and enhanced cardiac steatosis. Copyright © 2016 the American Physiological Society.

Overexpression of PGC-1α increases peroxisomal activity and mitochondrial fatty acid oxidation in human primary myotubes.

PubMed

Huang, Tai-Yu; Zheng, Donghai; Houmard, Joseph A; Brault, Jeffrey J; Hickner, Robert C; Cortright, Ronald N

2017-04-01

Peroxisomes are indispensable organelles for lipid metabolism in humans, and their biogenesis has been assumed to be under regulation by peroxisome proliferator-activated receptors (PPARs). However, recent studies in hepatocytes suggest that the mitochondrial proliferator PGC-1α (peroxisome proliferator-activated receptor gamma coactivator-1α) also acts as an upstream transcriptional regulator for enhancing peroxisomal abundance and associated activity. It is unknown whether the regulatory mechanism(s) for enhancing peroxisomal function is through the same node as mitochondrial biogenesis in human skeletal muscle (HSkM) and whether fatty acid oxidation (FAO) is affected. Primary myotubes from vastus lateralis biopsies from lean donors (BMI = 24.0 ± 0.6 kg/m 2 ; n = 6) were exposed to adenovirus encoding human PGC-1α or GFP control. Peroxisomal biogenesis proteins (peroxins) and genes ( PEXs ) responsible for proliferation and functions were assessed by Western blotting and real-time qRT-PCR, respectively. [1- 14 C]palmitic acid and [1- 14 C]lignoceric acid (exclusive peroxisomal-specific substrate) were used to assess mitochondrial oxidation of peroxisomal-derived metabolites. After overexpression of PGC-1α, 1 ) peroxisomal membrane protein 70 kDa (PMP70), PEX19, and mitochondrial citrate synthetase protein content were significantly elevated ( P < 0.05), 2 ) PGC-1α , PMP70 , key PEXs , and peroxisomal β-oxidation mRNA expression levels were significantly upregulated ( P < 0.05), and 3 ) a concomitant increase in lignoceric acid oxidation by both peroxisomal and mitochondrial activity was observed ( P < 0.05). These novel findings demonstrate that, in addition to the proliferative effect on mitochondria, PGC-1α can induce peroxisomal activity and accompanying elevations in long-chain and very-long-chain fatty acid oxidation by a peroxisomal-mitochondrial functional cooperation, as observed in HSkM cells. Copyright © 2017 the American Physiological Society.

Mitofusin gain and loss of function drive pathogenesis in Drosophila models of CMT2A neuropathy.

PubMed

El Fissi, Najla; Rojo, Manuel; Aouane, Aїcha; Karatas, Esra; Poliacikova, Gabriela; David, Claudine; Royet, Julien; Rival, Thomas

2018-06-13

Charcot-Marie-Tooth disease type 2A (CMT2A) is caused by dominant alleles of the mitochondrial pro-fusion factor Mitofusin 2 (MFN2). To address the consequences of these mutations on mitofusin activity and neuronal function, we generate Drosophila models expressing in neurons the two most frequent substitutions (R94Q and R364W, the latter never studied before) and two others localizing to similar domains (T105M and L76P). All alleles trigger locomotor deficits associated with mitochondrial depletion at neuromuscular junctions, decreased oxidative metabolism and increased mtDNA mutations, but they differently alter mitochondrial morphology and organization. Substitutions near or within the GTPase domain (R94Q, T105M) result in loss of function and provoke aggregation of unfused mitochondria. In contrast, mutations within helix bundle 1 (R364W, L76P) enhance mitochondrial fusion, as demonstrated by the rescue of mitochondrial alterations and locomotor deficits by over-expression of the fission factor DRP1. In conclusion, we show that both dominant negative and dominant active forms of mitofusin can cause CMT2A-associated defects and propose for the first time that excessive mitochondrial fusion drives CMT2A pathogenesis in a large number of patients. © 2018 The Authors.

Phytochemicals prevent mitochondrial membrane permeabilization and protect SH-SY5Y cells against apoptosis induced by PK11195, a ligand for outer membrane translocator protein.

PubMed

Wu, Yuqiu; Shamoto-Nagai, Masayo; Maruyama, Wakako; Osawa, Toshihiko; Naoi, Makoto

2017-01-01

Epidemiological studies present the beneficial effects of dietary habits on prevention of aging-associated decline of brain function. Phytochemicals, the second metabolites of food, protect neuronal cells from cell death in cellular models of neurodegenerative disorders, and the neuroprotective activity has been ascribed to the anti-oxidant and anti-inflammatory functions. In this paper, the cellular mechanism of neuroprotection by phytochemicals was investigated, using the cellular model of mitochondrial apoptosis induced by PK11195, a ligand of outer membrane translocator protein, in SH-SY5Y cells. PK11195 induced mitochondrial membrane permeabilization with rapid transit production of superoxide (superoxide flashes) and calcium release from mitochondria, and activated apoptosis signal pathway. Study on the structure-activity relationship of astaxanthin, ferulic acid derivatives, and sesame lignans revealed that these phytochemicals inhibited mitochondrial membrane permeabilization and protected cells from apoptosis. Ferulic acid derivatives and sesame lignans inhibited or enhanced the mitochondrial pore formation and cell death by PK11195 according to their amphiphilic properties, not directly depending on the antioxidant activity. Regulation of pore formation at mitochondrial membrane is discussed as a novel mechanism behind neuroprotective activity of phytochemicals in aging and age-associated neurodegenerative disorders, and also behind dual functions of phytochemicals in neuronal and cancer cells.

Dynamic Adaptation of Liver Mitochondria to Chronic Alcohol Feeding in Mice

PubMed Central

Han, Derick; Ybanez, Maria D.; Johnson, Heather S.; McDonald, Jeniece N.; Mesropyan, Lusine; Sancheti, Harsh; Martin, Gary; Martin, Alanna; Lim, Atalie M; Dara, Lily; Cadenas, Enrique; Tsukamoto, Hidekazu; Kaplowitz, Neil

2012-01-01

Liver mitochondria undergo dynamic alterations following chronic alcohol feeding to mice. Intragastric alcohol feeding to mice resulted in 1) increased state III respiration (109% compared with control) in isolated liver mitochondria, probably due to increased levels of complexes I, IV, and V being incorporated into the respiratory chain; 2) increased mitochondrial NAD+ and NADH levels (∼2-fold), with no change in the redox status; 3) alteration in mitochondrial morphology, with increased numbers of elongated mitochondria; and 4) enhanced mitochondrial biogenesis in the liver, which corresponded with an up-regulation of PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α). Oral alcohol feeding to mice, which is associated with less liver injury and steatosis, slightly enhanced respiration in isolated liver mitochondria (30.8% compared with control), lower than the striking increase caused by intragastric alcohol feeding. Mitochondrial respiration increased with both oral and intragastric alcohol feeding despite extensive N-acetylation of mitochondrial proteins. The alcohol-induced mitochondrial alterations are probably an adaptive response to enhance alcohol metabolism in the liver. Isolated liver mitochondria from alcohol-treated mice had a greater rate of acetaldehyde metabolism and respiration when treated with acetaldehyde than control. Aldehyde dehydrogenase-2 levels were unaltered in response to alcohol, suggesting that the greater acetaldehyde metabolism by isolated mitochondria from alcohol-treated mice was due to increased mitochondrial respiration that regenerated NAD+, the rate-limiting substrate in alcohol/acetaldehyde metabolism. Overall, our work suggests that mitochondrial plasticity in the liver may be an important adaptive response to the metabolic stress caused by alcohol intake and could potentially play a role in many other vital functions performed by the liver. PMID:23086958

Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer's disease.

PubMed

Sharoar, M G; Shi, Q; Ge, Y; He, W; Hu, X; Perry, G; Zhu, X; Yan, R

2016-09-01

Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains.

Translating the basic knowledge of mitochondrial functions to metabolic therapy: role of L-carnitine.

PubMed

Marcovina, Santica M; Sirtori, Cesare; Peracino, Andrea; Gheorghiade, Mihai; Borum, Peggy; Remuzzi, Giuseppe; Ardehali, Hossein

2013-02-01

Mitochondria play important roles in human physiological processes, and therefore, their dysfunction can lead to a constellation of metabolic and nonmetabolic abnormalities such as a defect in mitochondrial gene expression, imbalance in fuel and energy homeostasis, impairment in oxidative phosphorylation, enhancement of insulin resistance, and abnormalities in fatty acid metabolism. As a consequence, mitochondrial dysfunction contributes to the pathophysiology of insulin resistance, obesity, diabetes, vascular disease, and chronic heart failure. The increased knowledge on mitochondria and their role in cellular metabolism is providing new evidence that these disorders may benefit from mitochondrial-targeted therapies. We review the current knowledge of the contribution of mitochondrial dysfunction to chronic diseases, the outcomes of experimental studies on mitochondrial-targeted therapies, and explore the potential of metabolic modulators in the treatment of selected chronic conditions. As an example of such modulators, we evaluate the efficacy of the administration of L-carnitine and its analogues acetyl and propionyl L-carnitine in several chronic diseases. L-carnitine is intrinsically involved in mitochondrial metabolism and function as it plays a key role in fatty acid oxidation and energy metabolism. In addition to the transportation of free fatty acids across the inner mitochondrial membrane, L-carnitine modulates their oxidation rate and is involved in the regulation of vital cellular functions such as apoptosis. Thus, L-carnitine and its derivatives show promise in the treatment of chronic conditions and diseases associated with mitochondrial dysfunction but further translational studies are needed to fully explore their potential. Copyright © 2013 Mosby, Inc. All rights reserved.

Bcl-2 is a novel interacting partner for the 2-oxoglutarate carrier and a key regulator of mitochondrial glutathione

PubMed Central

Wilkins, Heather M.; Marquardt, Kristin; Lash, Lawrence H.; Linseman, Daniel A.

2011-01-01

Despite making up only a minor fraction of the total cellular glutathione, recent studies indicate that the mitochondrial glutathione pool is essential for cell survival. Selective depletion of mitochondrial glutathione is sufficient to sensitize cells to mitochondrial oxidative stress (MOS)1 and intrinsic apoptosis. Glutathione is synthesized exclusively in the cytoplasm and must be actively transported into mitochondria. Therefore, regulation of mitochondrial glutathione transport is a key factor in maintaining the antioxidant status of mitochondria. Bcl-2 is resident in the outer mitochondrial membrane where it acts as a central regulator of the intrinsic apoptotic cascade. In addition, Bcl-2 displays an antioxidant-like function that has been linked experimentally to the regulation of cellular glutathione content. We have previously demonstrated a novel interaction between recombinant Bcl-2 and reduced glutathione (GSH) which was antagonized by either Bcl-2 homology-3 domain (BH3) mimetics or a BH3-only protein, recombinant Bim. These previous findings prompted us to investigate if this novel Bcl-2/GSH interaction might play a role in regulating mitochondrial glutathione transport. Incubation of primary cultures of cerebellar granule neurons (CGNs) with the BH3 mimetic, HA14-1, induced MOS and caused specific depletion of the mitochondrial glutathione pool. Bcl-2 was co-immunoprecipitated with GSH following chemical cross-linking in CGNs and this Bcl-2/GSH interaction was antagonized by pre-incubation with HA14-1. Moreover, both HA14-1 and recombinant Bim inhibited GSH transport into isolated rat brain mitochondria. To further investigate a possible link between Bcl-2 function and mitochondrial glutathione transport, we next examined if Bcl-2 associated with the 2-oxoglutarate carrier (OGC), an inner mitochondrial membrane protein known to transport glutathione in liver and kidney. Following co-transfection of CHO cells, Bcl-2 was co-immunoprecipitated with OGC and this novel interaction was significantly enhanced by glutathione monoethylester (GSH-MEE). Similarly, recombinant Bcl-2 interacted with recombinant OGC in the presence of GSH. Bcl-2 and OGC co-transfection in CHO cells significantly increased the mitochondrial glutathione pool. Finally, the ability of Bcl-2 to protect CHO cells from apoptosis induced by hydrogen peroxide was significantly attenuated by the OGC inhibitor phenylsuccinate. These data suggest that GSH binding by Bcl-2 enhances its affinity for the OGC. Bcl-2 and OGC appear to act in a coordinated manner to increase the mitochondrial glutathione pool and enhance resistance of cells to oxidative stress. We conclude that regulation of mitochondrial glutathione transport is a principal mechanism by which Bcl-2 suppresses MOS. PMID:22115789

Miro1 Regulates Activity-Driven Positioning of Mitochondria within Astrocytic Processes Apposed to Synapses to Regulate Intracellular Calcium Signaling

PubMed Central

Stephen, Terri-Leigh; Higgs, Nathalie F.; Sheehan, David F.; Al Awabdh, Sana; López-Doménech, Guillermo; Arancibia-Carcamo, I. Lorena

2015-01-01

It is fast emerging that maintaining mitochondrial function is important for regulating astrocyte function, although the specific mechanisms that govern astrocyte mitochondrial trafficking and positioning remain poorly understood. The mitochondrial Rho-GTPase 1 protein (Miro1) regulates mitochondrial trafficking and detachment from the microtubule transport network to control activity-dependent mitochondrial positioning in neurons. However, whether Miro proteins are important for regulating signaling-dependent mitochondrial dynamics in astrocytic processes remains unclear. Using live-cell confocal microscopy of rat organotypic hippocampal slices, we find that enhancing neuronal activity induces transient mitochondrial remodeling in astrocytes, with a concomitant, transient reduction in mitochondrial trafficking, mediated by elevations in intracellular Ca2+. Stimulating neuronal activity also induced mitochondrial confinement within astrocytic processes in close proximity to synapses. Furthermore, we show that the Ca2+-sensing EF-hand domains of Miro1 are important for regulating mitochondrial trafficking in astrocytes and required for activity-driven mitochondrial confinement near synapses. Additionally, activity-dependent mitochondrial positioning by Miro1 reciprocally regulates the levels of intracellular Ca2+ in astrocytic processes. Thus, the regulation of intracellular Ca2+ signaling, dependent on Miro1-mediated mitochondrial positioning, could have important consequences for astrocyte Ca2+ wave propagation, gliotransmission, and ultimately neuronal function. SIGNIFICANCE STATEMENT Mitochondria are key cellular organelles that play important roles in providing cellular energy and buffering intracellular calcium ions. The mechanisms that control mitochondrial distribution within the processes of glial cells called astrocytes and the impact this may have on calcium signaling remains unclear. We show that activation of glutamate receptors or increased neuronal activity leads to the altered transport of mitochondria and their positioning at synapses dependent on a key mitochondrial trafficking protein called Miro1. We also show that, the control of mitochondrial movement and stopping by Miro plays an important role in regulating astrocyte calcium responses. Thus the regulation of intracellular calcium signaling, by Miro-mediated mitochondrial positioning, could have important consequences for astrocyte signaling and neuron–glial interactions. PMID:26631479

DDX3 DEAD-box RNA helicase plays a central role in mitochondrial protein quality control in Leishmania

PubMed Central

Padmanabhan, Prasad Kottayil; Zghidi-Abouzid, Ouafa; Samant, Mukesh; Dumas, Carole; Aguiar, Bruno Guedes; Estaquier, Jerome; Papadopoulou, Barbara

2016-01-01

DDX3 is a highly conserved member of ATP-dependent DEAD-box RNA helicases with multiple functions in RNA metabolism and cellular signaling. Here, we describe a novel function for DDX3 in regulating the mitochondrial stress response in the parasitic protozoan Leishmania. We show that genetic inactivation of DDX3 leads to the accumulation of mitochondrial reactive oxygen species (ROS) associated with a defect in hydrogen peroxide detoxification. Upon stress, ROS production is greatly enhanced, causing mitochondrial membrane potential loss, mitochondrial fragmentation, and cell death. Importantly, this phenotype is exacerbated upon oxidative stress in parasites forced to use the mitochondrial oxidative respiratory machinery. Furthermore, we show that in the absence of DDX3, levels of major components of the unfolded protein response as well as of polyubiquitinated proteins increase in the parasite, particularly in the mitochondrion, as an indicator of mitochondrial protein damage. Consistent with these findings, immunoprecipitation and mass-spectrometry studies revealed potential interactions of DDX3 with key components of the cellular stress response, particularly the antioxidant response, the unfolded protein response, and the AAA-ATPase p97/VCP/Cdc48, which is essential in mitochondrial protein quality control by driving proteosomal degradation of polyubiquitinated proteins. Complementation studies using DDX3 deletion mutants lacking conserved motifs within the helicase core support that binding of DDX3 to ATP is essential for DDX3's function in mitochondrial proteostasis. As a result of the inability of DDX3-depleted Leishmania to recover from ROS damage and to survive various stresses in the host macrophage, parasite intracellular development was impaired. Collectively, these observations support a central role for the Leishmania DDX3 homolog in preventing ROS-mediated damage and in maintaining mitochondrial protein quality control. PMID:27735940

O-GlcNAcomic Profiling Identifies Widespread O-Linked β-N-Acetylglucosamine Modification (O-GlcNAcylation) in Oxidative Phosphorylation System Regulating Cardiac Mitochondrial Function*♦

PubMed Central

Ma, Junfeng; Liu, Ting; Wei, An-Chi; Banerjee, Partha; O'Rourke, Brian; Hart, Gerald W.

2015-01-01

Dynamic cycling of O-linked β-N-acetylglucosamine (O-GlcNAc) on nucleocytoplasmic proteins serves as a nutrient sensor to regulate numerous biological processes. However, mitochondrial protein O-GlcNAcylation and its effects on function are largely unexplored. In this study, we performed a comparative analysis of the proteome and O-GlcNAcome of cardiac mitochondria from rats acutely (12 h) treated without or with thiamet-G (TMG), a potent and specific inhibitor of O-GlcNAcase. We then determined the functional consequences in mitochondria isolated from the two groups. O-GlcNAcomic profiling finds that over 88 mitochondrial proteins are O-GlcNAcylated, with the oxidative phosphorylation system as a major target. Moreover, in comparison with controls, cardiac mitochondria from TMG-treated rats did not exhibit altered protein abundance but showed overall elevated O-GlcNAcylation of many proteins. However, O-GlcNAc was unexpectedly down-regulated at certain sites of specific proteins. Concomitantly, TMG treatment resulted in significantly increased mitochondrial oxygen consumption rates, ATP production rates, and enhanced threshold for permeability transition pore opening by Ca2+. Our data reveal widespread and dynamic mitochondrial protein O-GlcNAcylation, serving as a regulator to their function. PMID:26446791

Quercetin attenuates mitochondrial dysfunction and biogenesis via upregulated AMPK/SIRT1 signaling pathway in OA rats.

PubMed

Qiu, Linan; Luo, Yuju; Chen, Xiaojuan

2018-07-01

Despite the severity of osteoarthritis (OA), current medical therapy strategies for OA aim at symptom control and pain reduction, as there is no ideal drug for effective OA treatment. OA rat model was used to explore the therapeutic function of quercetin on remission of OA, by determining the reactive oxygen species (ROS) levels, mitochondrial function and extracellular matrix integrity. Quercetin could attenuate ROS generation and augment the glutathione (GSH) and glutathione peroxidase (GPx) expression levels in OA rat. Quercetin not only enhanced mitochondrial membrane potential, oxygen consumption, adenosine triphosphate (ATP) levels in mitochondria, but also increased the mitochondrial copy number. Furthermore, the interlukin (IL)-1β-induced accumulation of nitric oxide (NO), matrixmetalloproteinase (MMP)-3) and MMP-13 could be suppressed by quercetin. Finally, we confirmed that the therapeutic properties of quercetin on OA might function through the adenosine monophosphate-activated protein kinase/sirtuin 1 (AMPK/SIRT1) signaling pathway. In summary, quercetin could alleviate OA through attenuating the ROS levels, reversing the mitochondrial dysfunction and keeping the integrality of extracellular matrix of joint cartilage. The underlying mechanism might involve the regulation of AMPK/SIRT1 signaling pathway. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Mitochondrial DNA Damage and Diseases

PubMed Central

Singh, Gyanesh; Pachouri, U C; Khaidem, Devika Chanu; Kundu, Aman; Chopra, Chirag; Singh, Pushplata

2015-01-01

Various endogenous and environmental factors can cause mitochondrial DNA (mtDNA) damage.  One of the reasons for enhanced mtDNA damage could be its proximity to the source of oxidants, and lack of histone-like protective proteins. Moreover, mitochondria contain inadequate DNA repair pathways, and, diminished DNA repair capacity may be one of the factors responsible for high mutation frequency of the mtDNA. mtDNA damage might cause impaired mitochondrial function, and, unrepaired mtDNA damage has been frequently linked with several diseases. Exploration of mitochondrial perspective of diseases might lead to a better understanding of several diseases, and will certainly open new avenues for detection, cure, and prevention of ailments. PMID:27508052

MOXI Is a Mitochondrial Micropeptide That Enhances Fatty Acid β-Oxidation.

PubMed

Makarewich, Catherine A; Baskin, Kedryn K; Munir, Amir Z; Bezprozvannaya, Svetlana; Sharma, Gaurav; Khemtong, Chalermchai; Shah, Akansha M; McAnally, John R; Malloy, Craig R; Szweda, Luke I; Bassel-Duby, Rhonda; Olson, Eric N

2018-06-26

Micropeptide regulator of β-oxidation (MOXI) is a conserved muscle-enriched protein encoded by an RNA transcript misannotated as non-coding. MOXI localizes to the inner mitochondrial membrane where it associates with the mitochondrial trifunctional protein, an enzyme complex that plays a critical role in fatty acid β-oxidation. Isolated heart and skeletal muscle mitochondria from MOXI knockout mice exhibit a diminished ability to metabolize fatty acids, while transgenic MOXI overexpression leads to enhanced β-oxidation. Additionally, hearts from MOXI knockout mice preferentially oxidize carbohydrates over fatty acids in an isolated perfused heart system compared to wild-type (WT) animals. MOXI knockout mice also exhibit a profound reduction in exercise capacity, highlighting the role of MOXI in metabolic control. The functional characterization of MOXI provides insight into the regulation of mitochondrial metabolism and energy homeostasis and underscores the regulatory potential of additional micropeptides that have yet to be identified. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Balneotherapy and coenzyme Q10 in clinical and experimental medicine.

PubMed

Gvozdjakova, Anna; Kucharska, Jarmila; Sykora, L'ubomir; Singh, Ram B

2014-01-01

Balneotherapy or Spa therapy is used in neurological, cardiovascular, musculoskeletal, dermatological and gynecological diseases, in infertility as well as in metabolic disturbances. Beneficial effects of balneotherapy at the metabolic level is not fully understood. Authors have documented enhancement of antioxidants concentrations (coenzyme Q10- CoQ(10-OX) and alpha-tocopherol) of women with gynecological diseases by treatment with natural mineral water (Spa Lucky balneotherapy, Slovakia). In an experiment with rats, drinking of Spa Lucky mineral water decreased oxidative stress and enhanced concentrations of antioxidants CoQ(9-OX), CoQ(10-OX) in the myocardium, and alpha-tocopherol in uterus, ovaries and myocardium. Drinking of Spa Lucky water by rats stimulated myocardial mitochondrial respiration and energy production, and diminished skeletal muscle mitochondrial function. Simultaneous ingestion of coenzyme Q10 with drinking spa water returned mitochondrial parameters to the values of the control group. This pilot study helps explain the role of antioxidants, oxidative stress and mitochondrial energy production in beneficial effects of Spa Lucky balneotherapy.

Cannabidiol Protects against Doxorubicin-Induced Cardiomyopathy by Modulating Mitochondrial Function and Biogenesis.

PubMed

Hao, Enkui; Mukhopadhyay, Partha; Cao, Zongxian; Erdélyi, Katalin; Holovac, Eileen; Liaudet, Lucas; Lee, Wen-Shin; Haskó, György; Mechoulam, Raphael; Pacher, Pál

2015-01-06

Doxorubicin (DOX) is a widely used, potent chemotherapeutic agent; however, its clinical application is limited because of its dose-dependent cardiotoxicity. DOX's cardiotoxicity involves increased oxidative/nitrative stress, impaired mitochondrial function in cardiomyocytes/endothelial cells and cell death. Cannabidiol (CBD) is a nonpsychotropic constituent of marijuana, which is well tolerated in humans, with antioxidant, antiinflammatory and recently discovered antitumor properties. We aimed to explore the effects of CBD in a well-established mouse model of DOX-induced cardiomyopathy. DOX-induced cardiomyopathy was characterized by increased myocardial injury (elevated serum creatine kinase and lactate dehydrogenase levels), myocardial oxidative and nitrative stress (decreased total glutathione content and glutathione peroxidase 1 activity, increased lipid peroxidation, 3-nitrotyrosine formation and expression of inducible nitric oxide synthase mRNA), myocardial cell death (apoptotic and poly[ADP]-ribose polymerase 1 [PARP]-dependent) and cardiac dysfunction (decline in ejection fraction and left ventricular fractional shortening). DOX also impaired myocardial mitochondrial biogenesis (decreased mitochondrial copy number, mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1-alpha, peroxisome proliferator-activated receptor alpha, estrogen-related receptor alpha), reduced mitochondrial function (attenuated complex I and II activities) and decreased myocardial expression of uncoupling protein 2 and 3 and medium-chain acyl-CoA dehydrogenase mRNA. Treatment with CBD markedly improved DOX-induced cardiac dysfunction, oxidative/nitrative stress and cell death. CBD also enhanced the DOX-induced impaired cardiac mitochondrial function and biogenesis. These data suggest that CBD may represent a novel cardioprotective strategy against DOX-induced cardiotoxicity, and the above-described effects on mitochondrial function and biogenesis may contribute to its beneficial properties described in numerous other models of tissue injury.

Cannabidiol Protects against Doxorubicin-Induced Cardiomyopathy by Modulating Mitochondrial Function and Biogenesis

PubMed Central

Hao, Enkui; Mukhopadhyay, Partha; Cao, Zongxian; Erdélyi, Katalin; Holovac, Eileen; Liaudet, Lucas; Lee, Wen-Shin; Haskó, György; Mechoulam, Raphael; Pacher, Pál

2015-01-01

Doxorubicin (DOX) is a widely used, potent chemotherapeutic agent; however, its clinical application is limited because of its dose-dependent cardiotoxicity. DOX’s cardiotoxicity involves increased oxidative/nitrative stress, impaired mitochondrial function in cardiomyocytes/endothelial cells and cell death. Cannabidiol (CBD) is a nonpsychotropic constituent of marijuana, which is well tolerated in humans, with antioxidant, antiinflammatory and recently discovered antitumor properties. We aimed to explore the effects of CBD in a well-established mouse model of DOX-induced cardiomyopathy. DOX-induced cardiomyopathy was characterized by increased myocardial injury (elevated serum creatine kinase and lactate dehydrogenase levels), myocardial oxidative and nitrative stress (decreased total glutathione content and glutathione peroxidase 1 activity, increased lipid peroxidation, 3-nitrotyrosine formation and expression of inducible nitric oxide synthase mRNA), myocardial cell death (apoptotic and poly[ADP]-ribose polymerase 1 [PARP]-dependent) and cardiac dysfunction (decline in ejection fraction and left ventricular fractional shortening). DOX also impaired myocardial mitochondrial biogenesis (decreased mitochondrial copy number, mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1-alpha, peroxisome proliferator-activated receptor alpha, estrogen-related receptor alpha), reduced mitochondrial function (attenuated complex I and II activities) and decreased myocardial expression of uncoupling protein 2 and 3 and medium-chain acyl-CoA dehydrogenase mRNA. Treatment with CBD markedly improved DOX-induced cardiac dysfunction, oxidative/nitrative stress and cell death. CBD also enhanced the DOX-induced impaired cardiac mitochondrial function and biogenesis. These data suggest that CBD may represent a novel cardioprotective strategy against DOX-induced cardiotoxicity, and the above-described effects on mitochondrial function and biogenesis may contribute to its beneficial properties described in numerous other models of tissue injury. PMID:25569804

Proteomic Profiling of Mitochondrial Enzymes during Skeletal Muscle Aging.

PubMed

Staunton, Lisa; O'Connell, Kathleen; Ohlendieck, Kay

2011-03-07

Mitochondria are of central importance for energy generation in skeletal muscles. Expression changes or functional alterations in mitochondrial enzymes play a key role during myogenesis, fibre maturation, and various neuromuscular pathologies, as well as natural fibre aging. Mass spectrometry-based proteomics suggests itself as a convenient large-scale and high-throughput approach to catalogue the mitochondrial protein complement and determine global changes during health and disease. This paper gives a brief overview of the relatively new field of mitochondrial proteomics and discusses the findings from recent proteomic surveys of mitochondrial elements in aged skeletal muscles. Changes in the abundance, biochemical activity, subcellular localization, and/or posttranslational modifications in key mitochondrial enzymes might be useful as novel biomarkers of aging. In the long term, this may advance diagnostic procedures, improve the monitoring of disease progression, help in the testing of side effects due to new drug regimes, and enhance our molecular understanding of age-related muscle degeneration.

Mitochondrial Dysfunction, Through Impaired Autophagy, Leads to Endoplasmic Reticulum Stress, Deregulated Lipid Metabolism, and Pancreatitis in Animal Models.

PubMed

Biczo, Gyorgy; Vegh, Eszter T; Shalbueva, Natalia; Mareninova, Olga A; Elperin, Jason; Lotshaw, Ethan; Gretler, Sophie; Lugea, Aurelia; Malla, Sudarshan R; Dawson, David; Ruchala, Piotr; Whitelegge, Julian; French, Samuel W; Wen, Li; Husain, Sohail Z; Gorelick, Fred S; Hegyi, Peter; Rakonczay, Zoltan; Gukovsky, Ilya; Gukovskaya, Anna S

2018-02-01

Little is known about the signaling pathways that initiate and promote acute pancreatitis (AP). The pathogenesis of AP has been associated with abnormal increases in cytosolic Ca 2+ , mitochondrial dysfunction, impaired autophagy, and endoplasmic reticulum (ER) stress. We analyzed the mechanisms of these dysfunctions and their relationships, and how these contribute to development of AP in mice and rats. Pancreatitis was induced in C57BL/6J mice (control) and mice deficient in peptidylprolyl isomerase D (cyclophilin D, encoded by Ppid) by administration of L-arginine (also in rats), caerulein, bile acid, or an AP-inducing diet. Parameters of pancreatitis, mitochondrial function, autophagy, ER stress, and lipid metabolism were measured in pancreatic tissue, acinar cells, and isolated mitochondria. Some mice with AP were given trehalose to enhance autophagic efficiency. Human pancreatitis tissues were analyzed by immunofluorescence. Mitochondrial dysfunction in pancreas of mice with AP was induced by either mitochondrial Ca 2+ overload or through a Ca 2+ overload-independent pathway that involved reduced activity of ATP synthase (80% inhibition in pancreatic mitochondria isolated from rats or mice given L-arginine). Both pathways were mediated by cyclophilin D and led to mitochondrial depolarization and fragmentation. Mitochondrial dysfunction caused pancreatic ER stress, impaired autophagy, and deregulation of lipid metabolism. These pathologic responses were abrogated in cyclophilin D-knockout mice. Administration of trehalose largely prevented trypsinogen activation, necrosis, and other parameters of pancreatic injury in mice with L-arginine AP. Tissues from patients with pancreatitis had markers of mitochondrial damage and impaired autophagy, compared with normal pancreas. In different animal models, we find a central role for mitochondrial dysfunction, and for impaired autophagy as its principal downstream effector, in development of AP. In particular, the pathway involving enhanced interaction of cyclophilin D with ATP synthase mediates L-arginine-induced pancreatitis, a model of severe AP the pathogenesis of which has remained unknown. Strategies to restore mitochondrial and/or autophagic function might be developed for treatment of AP. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

Alpha-lipoic acid attenuates endoplasmic reticulum stress-induced insulin resistance by improving mitochondrial function in HepG2 cells.

PubMed

Lei, Lin; Zhu, Yiwei; Gao, Wenwen; Du, Xiliang; Zhang, Min; Peng, Zhicheng; Fu, Shoupeng; Li, Xiaobing; Zhe, Wang; Li, Xinwei; Liu, Guowen

2016-10-01

Alpha-lipoic acid (ALA) has been reported to have beneficial effects for improving insulin sensitivity. However, the underlying molecular mechanism of the beneficial effects remains poorly understood. Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are considered causal factors that induce insulin resistance. In this study, we investigated the effect of ALA on the modulation of insulin resistance in ER-stressed HepG2 cells, and we explored the potential mechanism of this effect. HepG2 cells were incubated with tunicamycin (Tun) for 6h to establish an ER stress cell model. Tun treatment induced ER stress, mitochondrial dysfunction and insulin resistance. Interestingly, ALA had no significant effect on ER stress signals. Pretreatment of the ER stress cell model with ALA for 24h improved insulin sensitivity, restored the expression levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes and increased intracellular ATP production. Moreover, ALA augmented the β-oxidation capacity of the mitochondria. Importantly, ALA treatment could decrease oligomycin-induced mitochondrial dysfunction and then improved insulin resistance. Taken together, our data suggest that ALA prevents ER stress-induced insulin resistance by enhancing mitochondrial function. Copyright © 2016 Elsevier Inc. All rights reserved.

NLRX1 prevents mitochondrial induced apoptosis and enhances macrophage antiviral immunity by interacting with influenza virus PB1-F2 protein

PubMed Central

Jaworska, Joanna; Coulombe, François; Downey, Jeffrey; Tzelepis, Fanny; Shalaby, Karim; Tattoli, Ivan; Berube, Julie; Rousseau, Simon; Martin, James G.; Girardin, Stephen E.; McCullers, Jonathan A.; Divangahi, Maziar

2014-01-01

To subvert host immunity, influenza A virus (IAV) induces early apoptosis in innate immune cells by disrupting mitochondria membrane potential via its polymerase basic protein 1-frame 2 (PB1-F2) accessory protein. Whether immune cells have mechanisms to counteract PB1-F2–mediated apoptosis is currently unknown. Herein, we define that the host mitochondrial protein nucleotide-binding oligomerization domain-like receptor (NLR)X1 binds to viral protein PB1-F2, preventing IAV-induced macrophage apoptosis and promoting both macrophage survival and type I IFN signaling. We initially observed that Nlrx1-deficient mice infected with IAV exhibited increased pulmonary viral replication, as well as enhanced inflammatory-associated pulmonary dysfunction and morbidity. Analysis of the lungs of IAV-infected mice revealed markedly enhanced leukocyte recruitment but impaired production of type I IFN in Nlrx1−/− mice. Impaired type I IFN production and enhanced viral replication was recapitulated in Nlrx1−/− macrophages and was associated with increased mitochondrial mediated apoptosis. Through gain- and loss-of-function strategies for protein interaction, we identified that NLRX1 directly bound PB1-F2 in the mitochondria of macrophages. Using a recombinant virus lacking PB1-F2, we confirmed that deletion of PB1-F2 abrogated NLRX1-dependent macrophage type I IFN production and apoptosis. Thus, our results demonstrate that NLRX1 acts as a mitochondrial sentinel protecting macrophages from PB1-F2–induced apoptosis and preserving their antiviral function. We further propose that NLRX1 is critical for macrophage immunity against IAV infection by sensing the extent of viral replication and maintaining a protective balance between antiviral immunity and excessive inflammation within the lungs. PMID:24799673

Ferulic acid with ascorbic acid synergistically extenuates the mitochondrial dysfunction during beta-adrenergic catecholamine induced cardiotoxicity in rats.

PubMed

Yogeeta, Surinder Kumar; Raghavendran, Hanumantha Rao Balaji; Gnanapragasam, Arunachalam; Subhashini, Rajakannu; Devaki, Thiruvengadam

2006-10-27

Disruption of mitochondria and free radical mediated tissue injury have been reported during cardiotoxicity induced by isoproterenol (ISO), a beta-adrenergic catecholamine. The present study was designed to investigate the effect of the combination of ferulic acid (FA) and ascorbic acid (AA) on the mitochondrial damage in ISO induced cardiotoxicity. Induction of rats with ISO (150 mg/kg b.wt., i.p.) for 2 days resulted in a significant decrease in the activities of respiratory chain enzymes (NADH dehydrogenase and cytochrome c-oxidase), tricarboxylic acid cycle enzymes (isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, alpha-ketoglutarate dehydrogenase), mitochondrial antioxidants (GPx, GST, SOD, CAT, GSH), cytochromes (b, c, c1, aa3) and in the level of mitochondrial phospholipids. A marked elevation in mitochondrial lipid peroxidation, mitochondrial levels of cholesterol, triglycerides and free fatty acids were also observed in ISO intoxicated rats. Pre-co-treatment with the combination of FA (20 mg/kg b.wt.) and AA (80 mg/kg b.wt.) orally for 6 days significantly enhanced the attenuation of these functional abnormalities and restored normal mitochondrial function when compared to individual drug treated groups. Mitigation of ISO induced biochemical and morphological changes in mitochondria were more pronounced with a combination of FA and AA rather than the individual drug treated groups. Transmission electron microscopic observations also correlated with these biochemical parameters. Hence, these findings demonstrate the synergistic ameliorative potential of FA and AA on mitochondrial function during beta-adrenergic catecholamine induced cardiotoxicity and associated oxidative stress in rats.

PINK1 deficiency enhances autophagy and mitophagy induction.

PubMed

Gómez-Sánchez, Rubén; Yakhine-Diop, Sokhna M S; Bravo-San Pedro, José M; Pizarro-Estrella, Elisa; Rodríguez-Arribas, Mario; Climent, Vicente; Martin-Cano, Francisco E; González-Soltero, María E; Tandon, Anurag; Fuentes, José M; González-Polo, Rosa A

2016-03-01

Parkinson's disease (PD) is a neurodegenerative disorder with poorly understood etiology. Increasing evidence suggests that age-dependent compromise of the maintenance of mitochondrial function is a key risk factor. Several proteins encoded by PD-related genes are associated with mitochondria including PTEN-induced putative kinase 1 (PINK1), which was first identified as a gene that is upregulated by PTEN. Loss-of-function PINK1 mutations induce mitochondrial dysfunction and, ultimately, neuronal cell death. To mitigate the negative effects of altered cellular functions cells possess a degradation mechanism called autophagy for recycling damaged components; selective elimination of dysfunctional mitochondria by autophagy is termed mitophagy. Our study indicates that autophagy and mitophagy are upregulated in PINK1-deficient cells, and is the first report to demonstrate efficient fluxes by one-step analysis. We propose that autophagy is induced to maintain cellular homeostasis under conditions of non-regulated mitochondrial quality control.

PINK1 deficiency enhances autophagy and mitophagy induction

PubMed Central

Gómez-Sánchez, Rubén; Yakhine-Diop, Sokhna M S; Bravo-San Pedro, José M; Pizarro-Estrella, Elisa; Rodríguez-Arribas, Mario; Climent, Vicente; Martin-Cano, Francisco E; González-Soltero, María E; Tandon, Anurag; Fuentes, José M; González-Polo, Rosa A

2016-01-01

Parkinson's disease (PD) is a neurodegenerative disorder with poorly understood etiology. Increasing evidence suggests that age-dependent compromise of the maintenance of mitochondrial function is a key risk factor. Several proteins encoded by PD-related genes are associated with mitochondria including PTEN-induced putative kinase 1 (PINK1), which was first identified as a gene that is upregulated by PTEN. Loss-of-function PINK1 mutations induce mitochondrial dysfunction and, ultimately, neuronal cell death. To mitigate the negative effects of altered cellular functions cells possess a degradation mechanism called autophagy for recycling damaged components; selective elimination of dysfunctional mitochondria by autophagy is termed mitophagy. Our study indicates that autophagy and mitophagy are upregulated in PINK1-deficient cells, and is the first report to demonstrate efficient fluxes by one-step analysis. We propose that autophagy is induced to maintain cellular homeostasis under conditions of non-regulated mitochondrial quality control. PMID:27308585

Grape seed proanthocyanidin extract protects human umbilical vein endothelial cells from indoxyl sulfate-induced injury via ameliorating mitochondrial dysfunction.

PubMed

Lu, Zhaoyu; Lu, Fuhua; Zheng, Yanqun; Zeng, Yuqun; Zou, Chuan; Liu, Xusheng

2016-01-01

To investigate the effects of grape seed proanthocyanidin extract (GSPE) on indoxyl sulfate-induced Human Umbilical Vein Endothelial Cells (HUVECs) injury in vitro and study its mechanism. HUVECs were incubated with indoxyl sulfate at concentrations in the range found in uremic patients. Then we determined the effect of indoxyl sulfate on endothelial phenotype, endothelial function, ROS (reactive oxygen species), cell apoptosis and mitochondrial function. In addition, we detected whether GSPE can suppress the injury of HUVECs induced by indoxyl sulfate and probe the mechanism underlying the protective effects of GSPE by analyzing mitochondrial dysfunction. GSPE treatment significantly attenuated indoxyl sulfate-induced HVUECs injury in a dose- and time-dependent manner. GSPE-enhanced eNOS and VE-cadherin expression, inhibited intracellular ROS level and cell apoptosis, adjust mitochondrial membrane potential and reduced 8-hydroxy-desoxyguanosine (8-OHdG) level induced by indoxyl sulfate. These results suggest that GSPE prevents HUVECs from indoxyl sulfate-induced injury by ameliorating mitochondrial dysfunction and may be a promising agent for treating uremia toxin-induced injury.

The plant i-AAA protease controls the turnover of an essential mitochondrial protein import component.

PubMed

Opalińska, Magdalena; Parys, Katarzyna; Murcha, Monika W; Jańska, Hanna

2018-01-29

Mitochondria are multifunctional organelles that play a central role in energy metabolism. Owing to the life-essential functions of these organelles, mitochondrial content, quality and dynamics are tightly controlled. Across the species, highly conserved ATP-dependent proteases prevent malfunction of mitochondria through versatile activities. This study focuses on a molecular function of the plant mitochondrial inner membrane-embedded AAA protease (denoted i -AAA) FTSH4, providing its first bona fide substrate. Here, we report that the abundance of the Tim17-2 protein, an essential component of the TIM17:23 translocase (Tim17-2 together with Tim50 and Tim23), is directly controlled by the proteolytic activity of FTSH4. Plants that are lacking functional FTSH4 protease are characterized by significantly enhanced capacity of preprotein import through the TIM17:23-dependent pathway. Taken together, with the observation that FTSH4 prevents accumulation of Tim17-2, our data point towards the role of this i -AAA protease in the regulation of mitochondrial biogenesis in plants. © 2018. Published by The Company of Biologists Ltd.

Complex IV Deficient Surf1−/− Mice Initiate Mitochondrial Stress Responses

PubMed Central

Pulliam, Daniel A.; Deepa, Sathyaseelan S.; Liu, Yuhong; Hill, Shauna; Lin, Ai-Ling; Bhattacharya, Arunabh; Shi, Yun; Sloane, Lauren; Viscomi, Carlo; Zeviani, Massimo; Van Remmen, Holly

2014-01-01

Summary Mutations in SURF1 cytochrome c oxidase (COX) assembly protein are associated with Leigh’s syndrome, a human mitochondrial disorder that manifests as severe mitochondrial phenotypes and early lethality. In contrast, mice lacking the Surf1 protein (Surf1−/−) are viable and were previously shown to have enhanced longevity and a greater than 50% reduction in COX activity. We measured mitochondrial function in heart and skeletal muscle, and despite the significant reduction in COX activity, we found little or no difference in reactive oxygen species (ROS) generation, membrane potential, ATP production or respiration in isolated mitochondria from Surf1−/− mice compared to wild-type. However, blood lactate levels are elevated and Surf1−/− mice have reduced running endurance, suggesting compromised mitochondrial energy metabolism in vivo. Decreased COX activity in Surf1−/− mice is associated with increased markers of mitochondrial biogenesis (PGC-1α and VDAC) in both heart and skeletal muscle. While mitochondrial biogenesis is a common response in the two tissues, skeletal muscle have an up-regulation of the mitochondrial unfolded protein response (UPRMT) and heart exhibits induction of the Nrf2 antioxidant response pathway. These data are the first to report induction of the UPRMT in a mammalian model of diminished COX activity. In addition our results suggest that impaired mitochondrial function can lead to induction of mitochondrial stress pathways to confer protective effects on cellular homeostasis. Loss of complex IV assembly factor Surf1 in mice results in compensatory responses including mitochondrial biogenesis, the nrf2 pathway and the mitochondrial unfolded protein response. This compensatory response may contribute to the lack of deleterious phenotypes under basal conditions. PMID:24911525

Drosophila mitochondrial topoisomerase III alpha affects the aging process via maintenance of mitochondrial function and genome integrity.

PubMed

Tsai, Han-Zen; Lin, Ren-Kuo; Hsieh, Tao-Shih

2016-04-12

Mitochondria play important roles in providing metabolic energy and key metabolites for synthesis of cellular building blocks. Mitochondria have additional functions in other cellular processes, including programmed cell death and aging. A previous study revealed Drosophila mitochondrial topoisomerase III alpha (Top3α) contributes to the maintenance of the mitochondrial genome and male germ-line stem cells. However, the involvement of mitochondrial Top3α in the mitochondrion-mediated aging process remains unclear. In this study, the M1L flies, in which Top3α protein lacks the mitochondrial import sequence and is thus present in cell nuclei but not in mitochondria, is used as a model system to examine the role of mitochondrial Top3α in the aging of fruit flies. Here, we reported that M1L flies exhibit mitochondrial defects which affect the aging process. First, we observed that M1L flies have a shorter life span, which was correlated with a significant reduction in the mitochondrial DNA copy number, the mitochondrial membrane potential, and ATP content compared with those of both wildtype and transgene-rescued flies of the same age. Second, we performed a mobility assay and electron microscopic analysis to demonstrate that the locomotion defect and mitophagy of M1L flies were enhanced with age, as compared with the controls. Finally, we showed that the correlation between the mtDNA deletion level and aging in M1L flies resembles what was reported in mammalian systems. The results reported here demonstrate that mitochondrial Top3α ablation results in mitochondrial genome instability and its dysfunction, thereby accelerating the aging process.

Altered expression of prohibitin in psoriatic lesions and its cellular implication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Soon Young; Kim, Younghwa; Hwang, Ha Young

2007-08-31

Psoriasis is characterized by excessive proliferation of keratinocytes accompanying acanthosis and incomplete differentiation. Prohibitin was investigated by examining its function of HaCaT as well as psoriasis. Psoriatic involved skin revealed high level of prohibitin in the basal layer. Prohibitin was analyzed by applying RNAi (PHBi) with HaCaT, which demonstrated increased S-phase. PHBi showed enhanced sensitivity to anthralin-mediated cell death due to enhanced loss of mitochondrial membrane potential, suggesting a protective role of prohibitin against apoptosis. Collectively, prohibitin plays a role both in cell cycle regulation and in maintaining mitochondrial integrity, implying its association with pathogenesis of psoriasis.

Cisplatin Induces a Mitochondrial-ROS Response That Contributes to Cytotoxicity Depending on Mitochondrial Redox Status and Bioenergetic Functions

PubMed Central

Marullo, Rossella; Werner, Erica; Degtyareva, Natalya; Moore, Bryn; Altavilla, Giuseppe; Ramalingam, Suresh S.; Doetsch, Paul W.

2013-01-01

Cisplatin is one of the most effective and widely used anticancer agents for the treatment of several types of tumors. The cytotoxic effect of cisplatin is thought to be mediated primarily by the generation of nuclear DNA adducts, which, if not repaired, cause cell death as a consequence of DNA replication and transcription blockage. However, the ability of cisplatin to induce nuclear DNA (nDNA) damage per se is not sufficient to explain its high degree of effectiveness nor the toxic effects exerted on normal, post-mitotic tissues. Oxidative damage has been observed in vivo following exposure to cisplatin in several tissues, suggesting a role for oxidative stress in the pathogenesis of cisplatin-induced dose-limiting toxicities. However, the mechanism of cisplatin-induced generation of ROS and their contribution to cisplatin cytotoxicity in normal and cancer cells is still poorly understood. By employing a panel of normal and cancer cell lines and the budding yeast Saccharomyces cerevisiae as model system, we show that exposure to cisplatin induces a mitochondrial-dependent ROS response that significantly enhances the cytotoxic effect caused by nDNA damage. ROS generation is independent of the amount of cisplatin-induced nDNA damage and occurs in mitochondria as a consequence of protein synthesis impairment. The contribution of cisplatin-induced mitochondrial dysfunction in determining its cytotoxic effect varies among cells and depends on mitochondrial redox status, mitochondrial DNA integrity and bioenergetic function. Thus, by manipulating these cellular parameters, we were able to enhance cisplatin cytotoxicity in cancer cells. This study provides a new mechanistic insight into cisplatin-induced cell killing and may lead to the design of novel therapeutic strategies to improve anticancer drug efficacy. PMID:24260552

Indian Ginseng (Withania somnifera) supplementation ameliorates oxidative stress and mitochondrial dysfunctions in experimental model of stroke.

PubMed

Sood, Abhilasha; Mehrotra, Arpit; Dhawan, Devinder K; Sandhir, Rajat

2018-04-18

Stroke is an increasingly prevalent clinical condition and second leading cause of death globally. The present study evaluated the therapeutic potential of Indian Ginseng, also known as Withania somnifera (WS), supplementation on middle cerebral artery occlusion (MCAO) induced mitochondrial dysfunctions in experimental model of ischemic stroke. Stroke was induced in animals by occluding the middle cerebral artery, followed by reperfusion injury. Ischemia reperfusion injury resulted in increased oxidative stress indicated by increased reactive oxygen species and protein carbonyl levels; compromised antioxidant system; in terms of reduced superoxide dismutase and catalase activity, along with reduction in GSH levels and the redox ratio, impaired mitochondrial functions and enhanced expression of apoptosis markers. Ischemia reperfusion injury induced mitochondrial dysfunctions in terms of (i) reduced activity of the mitochondrial respiratory chain enzymes, (ii) reduced histochemical staining of complex-II and IV, (iii) reduced in-gel activity of mitochondrial complex-I to V, (iv) mitochondrial structural changes in terms of increased mitochondrial swelling, reduced mitochondrial membrane potential and ultrastructural changes. Additionally, an increase in the activity of caspase-3 and caspase-9 was also observed, along with altered expression of apoptotic proteins Bcl-2 and Bax in MCAO animals. MCAO animals also showed significant impairment in cognitive functions assessed using Y maze test. WS pre-supplementation, on the other hand ameliorated MCAO induced oxidative stress, mitochondrial dysfunctions, apoptosis and cognitive impairments. The results show protective effect of WS pre-supplementation in ischemic stroke and are suggestive of its potential application in stroke management.

Functional linkage between NOXA and Bim in mitochondrial apoptotic events.

PubMed

Han, Jie; Goldstein, Leslie A; Hou, Wen; Rabinowich, Hannah

2007-06-01

NOXA is a BH3-only protein whose expression is induced by certain p53-depenent or independent apoptotic stimuli. Both NOXA and Bim are avid binders of Mcl-1, but a functional linkage between these BH3-only proteins has not yet been reported. In this study, we demonstrate that Mcl-1 binding of endogenously induced NOXA interferes with the ability of Mcl-1 to efficiently sequester endogenous Bim, as Bim is displaced from its complex with Mcl-1. Induced NOXA significantly enhances the UV sensitivity of cells, and the ensuing mitochondrial depolarization is entirely abrogated by Bim knockdown. These results demonstrate a Mcl-1-mediated cross-talk between endogenous NOXA and Bim that occurs upstream of the Bak/Bax-dependent execution of UV-induced mitochondrial depolarization. The current findings demonstrate that the mitochondrial response to an induced expression of NOXA is executed by endogenous Bim and suggest a plausible mechanism for the observed NOXA-Bim linkage.

Caloric Restriction-Induced Extension of Chronological Lifespan Requires Intact Respiration in Budding Yeast.

PubMed

Kwon, Young-Yon; Lee, Sung-Keun; Lee, Cheol-Koo

2017-04-01

Caloric restriction (CR) has been shown to extend lifespan and prevent cellular senescence in various species ranging from yeast to humans. Many effects of CR may contribute to extend lifespan. Specifically, CR prevents oxidative damage from reactive oxygen species (ROS) by enhancing mitochondrial function. In this study, we characterized 33 single electron transport chain (ETC) gene-deletion strains to identify CR-induced chronological lifespan (CLS) extension mechanisms. Interestingly, defects in 17 of these 33 ETC gene-deleted strains showed loss of both respiratory function and CR-induced CLS extension. On the contrary, the other 16 respiration-capable mutants showed increased CLS upon CR along with increased mitochondrial membrane potential (MMP) and intracellular adenosine triphosphate (ATP) levels, with decreased mitochondrial superoxide generation. We measured the same parameters in the 17 non-respiratory mutants upon CR. CR simultaneously increased MMP and mitochondrial superoxide generation without altering intracellular ATP levels. In conclusion, respiration is essential for CLS extension by CR and is important for balancing MMP, ROS, and ATP levels.

Rapid Communication: Dietary selenium improves skeletal muscle mitochondrial biogenesis in young equine athletes.

PubMed

White, S H; Wohlgemuth, S; Li, C; Warren, L K

2017-09-01

Exercise is known to promote mitochondrial biogenesis in skeletal muscle as well as enhance mitochondrial function and efficiency in human and rodent models. These adaptations help to decrease exercise-associated production of reactive oxygen species, which can negatively affect health and performance if antioxidant mechanisms are overwhelmed. Little is known about the adaptations of mitochondria in response to exercise training in the growing horse or if supplementation with a dietary antioxidant can improve mitochondrial function. To evaluate the separate and combined effects of selenium (Se) supplementation, training, and an acute strenuous exercise bout on mitochondrial adaptations in young horses, 30 American Quarter Horse yearlings were randomly assigned to an exercise training group or a no-training group and, within each group, received either 0.1 or 0.3 mg Se/kg DM for 14 wk. The study was split into 2 phases (wk 0 to 8 and wk 9 to 14), with half of the trained horses switched to the opposite dietary treatment in Phase 2. At the end of each phase, all horses underwent a 120-min submaximal exercise test (SET; SET 1 and SET 2). Biopsies of the middle gluteal muscle were collected before and after each phase of the study and in response to each SET and analyzed for markers of mitochondrial number and function. At rest, horses receiving 0.3 mg Se/kg DM had higher citrate synthase activity ( = 0.021) than horses receiving 0.1 mg Se/kg DM, indicating higher mitochondrial content. In contrast, cytochrome oxidase (CCO) activity was not affected by dietary Se overall, but horses that were dropped from 0.3 mg Se/kg DM to 0.1 mg Se/kg DM during Phase 2 showed a decrease ( = 0.034) in integrated CCO activity from wk 9 to 14, suggesting impaired mitochondrial function. Mitochondrial enzyme activities were unaffected by an acute, strenuous exercise bout (SET 1 and SET 2). Our relatively low-intensity exercise training protocol did not appear to induce functional mitochondrial adaptations. However, elevated dietary Se may impart beneficial effects on mitochondrial biogenesis during growth and training. A more strenuous exercise training protocol should be investigated to determine the potential benefits of elevated dietary Se for elite equine athletes.

A Select Subset of Electron Transport Chain Genes Associated with Optic Atrophy Link Mitochondria to Axon Regeneration in Caenorhabditis elegans.

PubMed

Knowlton, Wendy M; Hubert, Thomas; Wu, Zilu; Chisholm, Andrew D; Jin, Yishi

2017-01-01

The role of mitochondria within injured neurons is an area of active interest since these organelles are vital for the production of cellular energy in the form of ATP. Using mechanosensory neurons of the nematode Caenorhabditis elegans to test regeneration after neuronal injury in vivo , we surveyed genes related to mitochondrial function for effects on axon regrowth after laser axotomy. Genes involved in mitochondrial transport, calcium uptake, mitophagy, or fission and fusion were largely dispensable for axon regrowth, with the exception of eat-3/Opa1 . Surprisingly, many genes encoding components of the electron transport chain were dispensable for regrowth, except for the iron-sulfur proteins gas-1, nduf-2.2, nduf-7 , and isp-1 , and the putative oxidoreductase rad-8 . In these mutants, axonal development was essentially normal and axons responded normally to injury by forming regenerative growth cones, but were impaired in subsequent axon extension. Overexpression of nduf-2.2 or isp-1 was sufficient to enhance regrowth, suggesting that mitochondrial function is rate-limiting in axon regeneration. Moreover, loss of function in isp-1 reduced the enhanced regeneration caused by either a gain-of-function mutation in the calcium channel EGL-19 or overexpression of the MAP kinase DLK-1. While the cellular function of RAD-8 remains unclear, our genetic analyses place rad-8 in the same pathway as other electron transport genes in axon regeneration. Unexpectedly, rad-8 regrowth defects were suppressed by altered function in the ubiquinone biosynthesis gene clk-1 . Furthermore, we found that inhibition of the mitochondrial unfolded protein response via deletion of atfs-1 suppressed the defective regrowth in nduf-2.2 mutants. Together, our data indicate that while axon regeneration is not significantly affected by general dysfunction of cellular respiration, it is sensitive to the proper functioning of a select subset of electron transport chain genes, or to the cellular adaptations used by neurons under conditions of injury.

A Select Subset of Electron Transport Chain Genes Associated with Optic Atrophy Link Mitochondria to Axon Regeneration in Caenorhabditis elegans

PubMed Central

Knowlton, Wendy M.; Hubert, Thomas; Wu, Zilu; Chisholm, Andrew D.; Jin, Yishi

2017-01-01

The role of mitochondria within injured neurons is an area of active interest since these organelles are vital for the production of cellular energy in the form of ATP. Using mechanosensory neurons of the nematode Caenorhabditis elegans to test regeneration after neuronal injury in vivo, we surveyed genes related to mitochondrial function for effects on axon regrowth after laser axotomy. Genes involved in mitochondrial transport, calcium uptake, mitophagy, or fission and fusion were largely dispensable for axon regrowth, with the exception of eat-3/Opa1. Surprisingly, many genes encoding components of the electron transport chain were dispensable for regrowth, except for the iron-sulfur proteins gas-1, nduf-2.2, nduf-7, and isp-1, and the putative oxidoreductase rad-8. In these mutants, axonal development was essentially normal and axons responded normally to injury by forming regenerative growth cones, but were impaired in subsequent axon extension. Overexpression of nduf-2.2 or isp-1 was sufficient to enhance regrowth, suggesting that mitochondrial function is rate-limiting in axon regeneration. Moreover, loss of function in isp-1 reduced the enhanced regeneration caused by either a gain-of-function mutation in the calcium channel EGL-19 or overexpression of the MAP kinase DLK-1. While the cellular function of RAD-8 remains unclear, our genetic analyses place rad-8 in the same pathway as other electron transport genes in axon regeneration. Unexpectedly, rad-8 regrowth defects were suppressed by altered function in the ubiquinone biosynthesis gene clk-1. Furthermore, we found that inhibition of the mitochondrial unfolded protein response via deletion of atfs-1 suppressed the defective regrowth in nduf-2.2 mutants. Together, our data indicate that while axon regeneration is not significantly affected by general dysfunction of cellular respiration, it is sensitive to the proper functioning of a select subset of electron transport chain genes, or to the cellular adaptations used by neurons under conditions of injury. PMID:28539870

ONC201 kills breast cancer cells in vitro by targeting mitochondria.

PubMed

Greer, Yoshimi Endo; Porat-Shliom, Natalie; Nagashima, Kunio; Stuelten, Christina; Crooks, Dan; Koparde, Vishal N; Gilbert, Samuel F; Islam, Celia; Ubaldini, Ashley; Ji, Yun; Gattinoni, Luca; Soheilian, Ferri; Wang, Xiantao; Hafner, Markus; Shetty, Jyoti; Tran, Bao; Jailwala, Parthav; Cam, Maggie; Lang, Martin; Voeller, Donna; Reinhold, William C; Rajapakse, Vinodh; Pommier, Yves; Weigert, Roberto; Linehan, W Marston; Lipkowitz, Stanley

2018-04-06

We report a novel mechanism of action of ONC201 as a mitochondria-targeting drug in cancer cells. ONC201 was originally identified as a small molecule that induces transcription of TNF-related apoptosis-inducing ligand (TRAIL) and subsequently kills cancer cells by activating TRAIL death receptors. In this study, we examined ONC201 toxicity on multiple human breast and endometrial cancer cell lines. ONC201 attenuated cell viability in all cancer cell lines tested. Unexpectedly, ONC201 toxicity was not dependent on either TRAIL receptors nor caspases. Time-lapse live cell imaging revealed that ONC201 induces cell membrane ballooning followed by rupture, distinct from the morphology of cells undergoing apoptosis. Further investigation found that ONC201 induces phosphorylation of AMP-dependent kinase and ATP loss. Cytotoxicity and ATP depletion were significantly enhanced in the absence of glucose, suggesting that ONC201 targets mitochondrial respiration. Further analysis indicated that ONC201 indirectly inhibits mitochondrial respiration. Confocal and electron microscopic analysis demonstrated that ONC201 triggers mitochondrial structural damage and functional impairment. Moreover, ONC201 decreased mitochondrial DNA (mtDNA). RNAseq analysis revealed that ONC201 suppresses expression of multiple mtDNA-encoded genes and nuclear-encoded mitochondrial genes involved in oxidative phosphorylation and other mitochondrial functions. Importantly, fumarate hydratase deficient cancer cells and multiple cancer cell lines with reduced amounts of mtDNA were resistant to ONC201. These results indicate that cells not dependent on mitochondrial respiration are ONC201-resistant. Our data demonstrate that ONC201 kills cancer cells by disrupting mitochondrial function and further suggests that cancer cells that are dependent on glycolysis will be resistant to ONC201.

ONC201 kills breast cancer cells in vitro by targeting mitochondria

PubMed Central

Greer, Yoshimi Endo; Porat-Shliom, Natalie; Nagashima, Kunio; Stuelten, Christina; Crooks, Dan; Koparde, Vishal N.; Gilbert, Samuel F.; Islam, Celia; Ubaldini, Ashley; Ji, Yun; Gattinoni, Luca; Soheilian, Ferri; Wang, Xiantao; Hafner, Markus; Shetty, Jyoti; Tran, Bao; Jailwala, Parthav; Cam, Maggie; Lang, Martin; Voeller, Donna; Reinhold, William C.; Rajapakse, Vinodh; Pommier, Yves; Weigert, Roberto; Linehan, W. Marston; Lipkowitz, Stanley

2018-01-01

We report a novel mechanism of action of ONC201 as a mitochondria-targeting drug in cancer cells. ONC201 was originally identified as a small molecule that induces transcription of TNF-related apoptosis-inducing ligand (TRAIL) and subsequently kills cancer cells by activating TRAIL death receptors. In this study, we examined ONC201 toxicity on multiple human breast and endometrial cancer cell lines. ONC201 attenuated cell viability in all cancer cell lines tested. Unexpectedly, ONC201 toxicity was not dependent on either TRAIL receptors nor caspases. Time-lapse live cell imaging revealed that ONC201 induces cell membrane ballooning followed by rupture, distinct from the morphology of cells undergoing apoptosis. Further investigation found that ONC201 induces phosphorylation of AMP-dependent kinase and ATP loss. Cytotoxicity and ATP depletion were significantly enhanced in the absence of glucose, suggesting that ONC201 targets mitochondrial respiration. Further analysis indicated that ONC201 indirectly inhibits mitochondrial respiration. Confocal and electron microscopic analysis demonstrated that ONC201 triggers mitochondrial structural damage and functional impairment. Moreover, ONC201 decreased mitochondrial DNA (mtDNA). RNAseq analysis revealed that ONC201 suppresses expression of multiple mtDNA-encoded genes and nuclear-encoded mitochondrial genes involved in oxidative phosphorylation and other mitochondrial functions. Importantly, fumarate hydratase deficient cancer cells and multiple cancer cell lines with reduced amounts of mtDNA were resistant to ONC201. These results indicate that cells not dependent on mitochondrial respiration are ONC201-resistant. Our data demonstrate that ONC201 kills cancer cells by disrupting mitochondrial function and further suggests that cancer cells that are dependent on glycolysis will be resistant to ONC201. PMID:29719618

The Parkinson disease-related protein DJ-1 counteracts mitochondrial impairment induced by the tumour suppressor protein p53 by enhancing endoplasmic reticulum-mitochondria tethering.

PubMed

Ottolini, Denis; Calì, Tito; Negro, Alessandro; Brini, Marisa

2013-06-01

DJ-1 was first identified as an oncogene. More recently, mutations in its gene have been found causative for autosomal recessive familial Parkinson disease. Numerous studies support the DJ-1 role in the protection against oxidative stress and maintenance of mitochondria structure; however, the mechanism of its protective function remains largely unknown. We investigated whether mitochondrial Ca(2+) homeostasis, a key parameter in cell physiology, could be a target for DJ-1 action. Here, we show that DJ-1 modulates mitochondrial Ca(2+) transients induced upon cell stimulation with an 1,4,5-inositol-tris-phosphate agonist by favouring the endoplasmic reticulum (ER)-mitochondria tethering. A reduction of DJ-1 levels results in mitochondria fragmentation and decreased mitochondrial Ca(2+) uptake in stimulated cells. To functionally couple these effects with the well-recognized cytoprotective role of DJ-1, we investigated its action in respect to the tumour suppressor p53. p53 overexpression in HeLa cells impairs their ability to accumulate Ca(2+) in the mitochondrial matrix, causes alteration of the mitochondrial morphology and reduces ER-mitochondria contact sites. Mitochondrial impairments are independent from Drp1 activation, since the co-expression of the dominant negative mutant of Drp1 failed to abolish them. DJ-1 overexpression prevents these alterations by re-establishing the ER-mitochondria tethering. Similarly, the co-expression of the pro-fusion protein Mitofusin 2 blocks the effects induced by p53 on mitochondria, confirming that the modulation of the ER-mitochondria contact sites is critical to mitochondria integrity. Thus, the impairment of ER-mitochondria communication, as a consequence of DJ-1 loss-of-function, may be detrimental for mitochondria-related processes and be at the basis of mitochondrial dysfunction observed in Parkinson disease.

Chronic aerobic exercise training attenuates aortic stiffening and endothelial dysfunction through preserving aortic mitochondrial function in aged rats.

PubMed

Gu, Qi; Wang, Bing; Zhang, Xiao-Feng; Ma, Yan-Ping; Liu, Jian-Dong; Wang, Xiao-Ze

2014-08-01

Aging leads to large vessel arterial stiffening and endothelial dysfunction, which are important determinants of cardiovascular risk. The aim of present work was to assess the effects of chronic aerobic exercise training on aortic stiffening and endothelial dysfunction in aged rats and investigate the underlying mechanism about mitochondrial function. Chronic aerobic exercise training attenuated aortic stiffening with age marked by reduced collagen concentration, increased elastin concentration and reduced pulse wave velocity (PWV), and prevented aging-related endothelial dysfunction marked by improved endothelium-mediated vascular relaxation of aortas in response to acetylcholine. Chronic aerobic exercise training abated oxidative stress and nitrosative stress in aortas of aged rats. More importantly, we found that chronic aerobic exercise training in old rats preserved aortic mitochondrial function marked by reduced reactive oxygen species (ROS) formation and mitochondrial swelling, increased ATP formation and mitochondrial DNA content, and restored activities of complexes I and III and electron-coupling capacity between complexes I and III and between complexes II and III. In addition, it was found that chronic aerobic exercise training in old rats enhanced protein expression of uncoupling protein 2 (UCP-2), peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), manganese superoxide dismutase (Mn-SOD), aldehyde dehydrogenase 2 (ALDH-2), prohibitin (PHB) and AMP-activated kinase (AMPK) phosphorylation in aortas. In conclusion, chronic aerobic exercise training preserved mitochondrial function in aortas, which, at least in part, explained the aorta-protecting effects of exercise training in aging. Copyright © 2014 Elsevier Inc. All rights reserved.

Multistage Targeting Strategy Using Magnetic Composite Nanoparticles for Synergism of Photothermal Therapy and Chemotherapy.

PubMed

Wang, Yi; Wei, Guoqing; Zhang, Xiaobin; Huang, Xuehui; Zhao, Jingya; Guo, Xing; Zhou, Shaobing

2018-03-01

Mitochondrial-targeting therapy is an emerging strategy for enhanced cancer treatment. In the present study, a multistage targeting strategy using doxorubicin-loaded magnetic composite nanoparticles is developed for enhanced efficacy of photothermal and chemical therapy. The nanoparticles with a core-shell-SS-shell architecture are composed of a core of Fe 3 O 4 colloidal nanocrystal clusters, an inner shell of polydopamine (PDA) functionalized with triphenylphosphonium (TPP), and an outer shell of methoxy poly(ethylene glycol) linked to the PDA by disulfide bonds. The magnetic core can increase the accumulation of nanoparticles at the tumor site for the first stage of tumor tissue targeting. After the nanoparticles enter the tumor cells, the second stage of mitochondrial targeting is realized as the mPEG shell is detached from the nanoparticles by redox responsiveness to expose the TPP. Using near-infrared light irradiation at the tumor site, a photothermal effect is generated from the PDA photosensitizer, leading to a dramatic decrease in mitochondrial membrane potential. Simultaneously, the loaded doxorubicin can rapidly enter the mitochondria and subsequently damage the mitochondrial DNA, resulting in cell apoptosis. Thus, the synergism of photothermal therapy and chemotherapy targeting the mitochondria significantly enhances the cancer treatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exercise training in Tgαq*44 mice during the progression of chronic heart failure: cardiac vs. peripheral (soleus muscle) impairments to oxidative metabolism.

PubMed

Grassi, Bruno; Majerczak, Joanna; Bardi, Eleonora; Buso, Alessia; Comelli, Marina; Chlopicki, Stefan; Guzik, Magdalena; Mavelli, Irene; Nieckarz, Zenon; Salvadego, Desy; Tyrankiewicz, Urszula; Skórka, Tomasz; Bottinelli, Roberto; Zoladz, Jerzy A; Pellegrino, Maria Antonietta

2017-08-01

Cardiac function, skeletal (soleus) muscle oxidative metabolism, and the effects of exercise training were evaluated in a transgenic murine model (Tgα q *44) of chronic heart failure during the critical period between the occurrence of an impairment of cardiac function and the stage at which overt cardiac failure ensues (i.e., from 10 to 12 mo of age). Forty-eight Tgα q *44 mice and 43 wild-type FVB controls were randomly assigned to control groups and to groups undergoing 2 mo of intense exercise training (spontaneous running on an instrumented wheel). In mice evaluated at the beginning and at the end of training we determined: exercise performance (mean distance covered daily on the wheel); cardiac function in vivo (by magnetic resonance imaging); soleus mitochondrial respiration ex vivo (by high-resolution respirometry); muscle phenotype [myosin heavy chain (MHC) isoform content; citrate synthase (CS) activity]; and variables related to the energy status of muscle fibers [ratio of phosphorylated 5'-AMP-activated protein kinase (AMPK) to unphosphorylated AMPK] and mitochondrial biogenesis and function [peroxisome proliferative-activated receptor-γ coactivator-α (PGC-1α)]. In the untrained Tgα q *44 mice functional impairments of exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed. The impairment of mitochondrial respiration was related to the function of complex I of the respiratory chain, and it was not associated with differences in CS activity, MHC isoforms, p-AMPK/AMPK, and PGC-1α levels. Exercise training improved exercise performance and cardiac function, but it did not affect mitochondrial respiration, even in the presence of an increased percentage of type 1 MHC isoforms. Factors "upstream" of mitochondria were likely mainly responsible for the improved exercise performance. NEW & NOTEWORTHY Functional impairments in exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed in transgenic chronic heart failure mice, evaluated in the critical period between the occurrence of an impairment of cardiac function and the terminal stage of the disease. Exercise training improved exercise performance and cardiac function, but it did not affect the impaired mitochondrial respiration. Factors "upstream" of mitochondria, including an enhanced cardiovascular O 2 delivery, were mainly responsible for the functional improvement. Copyright © 2017 the American Physiological Society.

Sustained Activation of Akt Elicits Mitochondrial Dysfunction to Block Plasmodium falciparum Infection in the Mosquito Host

PubMed Central

Drexler, Anna L.; Antonova-Koch, Yevgeniya; Sakaguchi, Danielle; Napoli, Eleonora; Wong, Sarah; Price, Mark S.; Eigenheer, Richard; Phinney, Brett S.; Pakpour, Nazzy; Pietri, Jose E.; Cheung, Kong; Georgis, Martha; Riehle, Michael

2013-01-01

The overexpression of activated, myristoylated Akt in the midgut of female transgenic Anopheles stephensi results in resistance to infection with the human malaria parasite Plasmodium falciparum but also decreased lifespan. In the present study, the understanding of mitochondria-dependent midgut homeostasis has been expanded to explain this apparent paradox in an insect of major medical importance. Given that Akt signaling is essential for cell growth and survival, we hypothesized that sustained Akt activation in the mosquito midgut would alter the balance of critical pathways that control mitochondrial dynamics to enhance parasite killing at some cost to survivorship. Toxic reactive oxygen and nitrogen species (RNOS) rise to high levels in the midgut after blood feeding, due to a combination of high NO production and a decline in FOXO-dependent antioxidants. Despite an apparent increase in mitochondrial biogenesis in young females (3 d), energy deficiencies were apparent as decreased oxidative phosphorylation and increased [AMP]/[ATP] ratios. In addition, mitochondrial mass was lower and accompanied by the presence of stalled autophagosomes in the posterior midgut, a critical site for blood digestion and stem cell-mediated epithelial maintenance and repair, and by functional degradation of the epithelial barrier. By 18 d, the age at which An. stephensi would transmit P. falciparum to human hosts, mitochondrial dysfunction coupled to Akt-mediated repression of autophagy/mitophagy was more evident and midgut epithelial structure was markedly compromised. Inhibition of RNOS by co-feeding of the nitric-oxide synthase inhibitor L-NAME at infection abrogated Akt-dependent killing of P. falciparum that begins within 18 h of infection in 3–5 d old mosquitoes. Hence, Akt-induced changes in mitochondrial dynamics perturb midgut homeostasis to enhance parasite resistance and decrease mosquito infective lifespan. Further, quality control of mitochondrial function in the midgut is necessary for the maintenance of midgut health as reflected in energy homeostasis and tissue repair and renewal. PMID:23468624

Protosappanin B protects PC12 cells against oxygen-glucose deprivation-induced neuronal death by maintaining mitochondrial homeostasis via induction of ubiquitin-dependent p53 protein degradation.

PubMed

Zeng, Ke-Wu; Liao, Li-Xi; Zhao, Ming-Bo; Song, Fang-Jiao; Yu, Qian; Jiang, Yong; Tu, Peng-Fei

2015-03-15

Protosappanin B (PTB) is a bioactive dibenzoxocin derivative isolated from Caesalpinia sappan L. Here, we investigated the neuroprotective effects and the potential mechanisms of PTB on oxygen-glucose deprivation (OGD)-injured PC12 cells. Results showed that PTB significantly increased cell viability, inhibited cell apoptosis and up-regulated the expression of growth-associated protein 43 (a marker of neural outgrowth). Moreover, our study revealed that PTB effectively maintained mitochondrial homeostasis by up-regulation of mitochondrial membrane potential (MMP), inhibition of cytochrome c release from mitochondria and inactivation of mitochondrial caspase-9/3 apoptosis pathway. Further study showed that PTB significantly promoted cytoplasmic component degradation of p53 protein, a key negative regulator for mitochondrial function, resulting in a release of Bcl-2 from p53-Bcl-2 complex and an enhancing translocation of Bcl-2 to mitochondrial outer membrane. Finally, we found the degradation of p53 protein was induced by PTB via activation of a MDM2-dependent ubiquitination process. Taken together, our findings provided a new viewpoint of neuronal protection strategy for anoxia and ischemic injury with natural small molecular dibenzoxocin derivative by activating ubiquitin-dependent p53 protein degradation as well as increasing mitochondrial function. Copyright © 2015 Elsevier B.V. All rights reserved.

Accelerated recovery of renal mitochondrial and tubule homeostasis with SIRT1/PGC-1α activation following ischemia–reperfusion injury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Funk, Jason A., E-mail: funkj@musc.edu; Schnellmann, Rick G., E-mail: schnell@musc.edu; Ralph H. Johnson VA Medical Center, Charleston, SC 29401

Kidney ischemia–reperfusion (I/R) injury elicits cellular injury in the proximal tubule, and mitochondrial dysfunction is a pathological consequence of I/R. Promoting mitochondrial biogenesis (MB) as a repair mechanism after injury may offer a unique strategy to restore both mitochondrial and organ function. Rats subjected to bilateral renal pedicle ligation for 22 min were treated once daily with the SIRT1 activator SRT1720 (5 mg/kg) starting 24 h after reperfusion until 72 h–144 h. SIRT1 expression was elevated in the renal cortex of rats after I/R + vehicle treatment (IRV), but was associated with less nuclear localization. SIRT1 expression was even furthermore » augmented and nuclear localization was restored in the kidneys of rats after I/R + SRT1720 treatment (IRS). PGC-1α was elevated at 72 h–144 h in IRV and IRS kidneys; however, SRT1720 treatment induced deacetylation of PGC-1α, a marker of activation. Mitochondrial proteins ATP synthase β, COX I, and NDUFB8, as well as mitochondrial respiration, were diminished 24 h–144 h in IRV rats, but were partially or fully restored in IRS rats. Urinary kidney injury molecule-1 (KIM-1) was persistently elevated in both IRV and IRS rats; however, KIM-1 tissue expression was attenuated in IRS rats. Additionally, sustained loss of Na{sup +},K{sup +}–ATPase expression and basolateral localization and elevated vimentin in IRV rats was normalized in IRS rats, suggesting restoration of a differentiated, polarized tubule epithelium. The results suggest that SRT1720 treatment expedited recovery of mitochondrial protein expression and function by enhancing MB, which was associated with faster proximal tubule repair. Targeting MB may offer unique therapeutic strategy following ischemic injury. - Highlights: • We examined recovery of mitochondrial and renal function after ischemia–reperfusion. • SRT1720 treatment after I/R induced mitochondrial biogenesis via SIRT1/PGC-1α. • Recovery of mitochondrial function was expedited with SRT1720 treatment. • Restoration of tubule homeostasis was expedited with SRT1720 treatment. • Activators of SIRT1 and PGC-1α may offer new therapeutic targets for AKI.« less

Emerging (and converging) pathways in Parkinson's disease: keeping mitochondrial wellness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cieri, Domenico; Brini, Marisa; Calì, Tito

The selective cell loss in the ventral component of the substantia nigra pars compacta and the presence of alpha-synuclein (α-syn)-rich intraneuronal inclusions called Lewy bodies are the pathological hallmarks of Parkinson's disease (PD), the most common motor system disorder whose aetiology remains largely elusive. Although most cases of PD are idiopathic, there are rare familial forms of the disease that can be traced to single gene mutations that follow Mendelian inheritance pattern. The study of several nuclear encoded proteins whose mutations are linked to the development of autosomal recessive and dominant forms of familial PD enhanced our understanding of biochemicalmore » and cellular mechanisms contributing to the disease and suggested that many signs of neurodegeneration result from compromised mitochondrial function. Here we present an overview of the current understanding of PD-related mitochondrial dysfunction including defects in bioenergetics and Ca{sup 2+} homeostasis, mitochondrial DNA mutations, altered mitochondrial dynamics and autophagy. We emphasize, in particular, the convergence of many “apparently” different pathways towards a common route involving mitochondria. Understanding whether mitochondrial dysfunction in PD represents the cause or the consequence of the disease is challenging and will help to define the pathogenic processes at the basis of the PD onset and progression. - Highlights: • Mitochondrial dysfunctions are a common feature of neurodegenerative diseases. • Many familial PD related proteins ensure mitochondrial function. • Mutations in PD genes differently affect mitochondria related activities.« less

Rapamycin enhances survival in a Drosophila model of mitochondrial disease.

PubMed

Wang, Adrienne; Mouser, Jacob; Pitt, Jason; Promislow, Daniel; Kaeberlein, Matt

2016-12-06

Pediatric mitochondrial disorders are a devastating category of diseases caused by deficiencies in mitochondrial function. Leigh Syndrome (LS) is the most common of these diseases with symptoms typically appearing within the first year of birth and progressing rapidly until death, usually by 6-7 years of age. Our lab has recently shown that genetic inhibition of the mechanistic target of rapamycin (TOR) rescues the short lifespan of yeast mutants with defective mitochondrial function, and that pharmacological inhibition of TOR by administration of rapamycin significantly rescues the shortened lifespan, neurological symptoms, and neurodegeneration in a mouse model of LS. However, the mechanism by which TOR inhibition exerts these effects, and the extent to which these effects can extend to other models of mitochondrial deficiency, are unknown. Here, we probe the effects of TOR inhibition in a Drosophila model of complex I deficiency. Treatment with rapamycin robustly suppresses the lifespan defect in this model of LS, without affecting behavioral phenotypes. Interestingly, this increased lifespan in response to TOR inhibition occurs in an autophagy-independent manner. Further, we identify a fat storage defect in the ND2 mutant flies that is rescued by rapamycin, supporting a model that rapamycin exerts its effects on mitochondrial disease in these animals by altering metabolism.

Mitochondrial NADH Fluorescence is Enhanced by Complex I Binding

PubMed Central

Blinova, Ksenia; Levine, Rodney L.; Boja, Emily S.; Griffiths, Gary L.; Shi, Zhen-Dan; Ruddy, Brian; Balaban, Robert S.

2012-01-01

Mitochondrial NADH fluorescence has been a useful tool in evaluating mitochondrial energetics both in vitro and in vivo. Mitochondrial NADH fluorescence is enhanced several fold in the matrix through extended fluorescence lifetimes (EFL). However, the actual binding sites responsible for NADH EFL are unknown. We tested the hypothesis that NADH binding to Complex I is a significant source of mitochondrial NADH fluorescence enhancement. To test this hypothesis, the effect of Complex I binding on NADH fluorescence efficiency was evaluated in purified protein, and in native gels of the entire porcine heart mitochondria proteome. To avoid the oxidation of NADH in these preparations, we conducted the binding experiments under anoxic conditions in a specially designed apparatus. Purified intact Complex I enhanced NADH fluorescence in native gels approximately 10 fold. However, no enhancement was detected in denatured individual Complex I subunit proteins. In the Clear and Ghost native gels of the entire mitochondrial proteome, NADH fluorescence enhancement was localized to regions where NADH oxidation occurred in the presence of oxygen. Inhibitor and mass spectroscopy studies revealed that the fluorescence enhancement was specific to Complex I proteins. No fluorescence enhancement was detected for MDH or other dehydrogenases in this assay system, at physiological mole fractions of the matrix proteins. These data suggest that NADH associated with Complex I significantly contributes to the overall mitochondrial NADH fluorescence signal and provides an explanation for the well established close correlation of mitochondrial NADH fluorescence and the metabolic state. PMID:18702505

Carbon monoxide stimulates astrocytic mitochondrial biogenesis via L-type Ca{sup 2+} channel-mediated PGC-1α/ERRα activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Yoon Kyung; Park, Joon Ha; Baek, Yi-Yong

Carbon monoxide (CO), derived by the enzymatic reaction of heme oxygenase (HO), is a cellular regulator of energy metabolism and cytoprotection; however, its underlying mechanism has not been clearly elucidated. Astrocytes pre-exposed to the CO-releasing compound CORM-2 increased mitochondrial biogenesis, mitochondrial electron transport components (cytochrome c, Cyt c; cytochrome c oxidase subunit 2, COX2), and ATP synthesis. The increased mitochondrial function was correlated with activation of AMP-activated protein kinase α and upregulation of HO-1, peroxisome proliferators-activated receptor γ-coactivator-1α (PGC-1α), and estrogen-related receptor α (ERRα). These events elicited by CORM-2 were suppressed by Ca{sup 2+} chelators, a HO inhibitor, and anmore » L-type Ca{sup 2+} channel blocker, but not other Ca{sup 2+} channel inhibitors. Among the HO byproducts, combined CORM-2 and bilirubin treatment effectively increased PGC-1α, Cyt c and COX2 expression, mitochondrial biogenesis, and ATP synthesis, and these increases were blocked by Ca{sup 2+} chelators. Moreover, cerebral ischemia significantly increased HO-1, PGC-1α, and ERRα levels, subsequently increasing Cyt c and COX2 expression, in wild-type mice, compared with HO-1{sup +/−} mice. These results suggest that HO-1-derived CO enhances mitochondrial biogenesis in astrocytes by activating L-type Ca{sup 2+} channel-mediated PGC-1α/ERRα axis, leading to maintenance of astrocyte function and neuroprotection/recovery against damage of brain function. - Highlights: • CORM-pretreated astrocytes induces mitochondrial biogenesis by activating L-type Ca{sup 2+} channel-mediated PGC-1α stabilization. • Cerebral ischemia increased electron transport chain proteins (e.g. Cyt c and COX2), in WT mice, compared with HO-1{sup +/−} mice. • CO/HO-1 pathway increases astrocytic mitochondrial functions via a PGC-1α/ERRα axis.« less

The AMPK-PPARGC1A pathway is required for antimicrobial host defense through activation of autophagy.

PubMed

Yang, Chul-Su; Kim, Jwa-Jin; Lee, Hye-Mi; Jin, Hyo Sun; Lee, Sang-Hee; Park, Ji-Hoon; Kim, Soung Jung; Kim, Jin-Man; Han, Yong-Mahn; Lee, Myung-Shik; Kweon, Gi Ryang; Shong, Minho; Jo, Eun-Kyeong

2014-05-01

AMP-activated protein kinase (AMPK) is a crucial energy sensor and plays a key role in integration of cellular functions to maintain homeostasis. Despite this, it is largely unknown whether targeting the AMPK pathway can be used as a therapeutic strategy for infectious diseases. Herein, we show that AMPK activation robustly induces antibacterial autophagy, which contributes to antimicrobial defense against Mycobacterium tuberculosis (Mtb). AMPK activation led to inhibition of Mtb-induced phosphorylation of the mechanistic target of rapamycin (MTOR) in macrophages. In addition, AMPK activation increased the genes involved in oxidative phosphorylation, mitochondrial ATP production, and biogenesis in Mtb-infected macrophages. Notably, peroxisome proliferator-activated receptor-gamma, coactivator 1α (PPARGC1A) was required for AMPK-mediated antimicrobial activity, as well as enhancement of mitochondrial function and biogenesis, in macrophages. Further, the AMPK-PPARGC1A pathway was involved in the upregulation of multiple autophagy-related genes via CCAAT/enhancer binding protein (C/EBP), β (CEBPB). PPARGC1A knockdown inhibited the AMPK-mediated induction of autophagy and impaired the fusion of phagosomes with MAP1LC3B (LC3B) autophagosomes in Mtb-infected macrophages. The link between autophagy, mitochondrial function, and antimicrobial activity was further demonstrated by studying LysMCre-mediated knockout of atg7, demonstrating mitochondrial ultrastructural defects and dysfunction, as well as blockade of antimicrobial activity against mycobacteria. Collectively, our results identify the AMPK-PPARGC1A axis as contributing to autophagy activation leading to an antimicrobial response, as a novel host defense mechanism.

Increased mitochondrial function downstream from KDM5A histone demethylase rescues differentiation in pRB-deficient cells

PubMed Central

Váraljai, Renáta; Islam, Abul B.M.M.K.; Beshiri, Michael L.; Rehman, Jalees; Lopez-Bigas, Nuria; Benevolenskaya, Elizaveta V.

2015-01-01

The retinoblastoma tumor suppressor protein pRb restricts cell growth through inhibition of cell cycle progression. Increasing evidence suggests that pRb also promotes differentiation, but the mechanisms are poorly understood, and the key question remains as to how differentiation in tumor cells can be enhanced in order to diminish their aggressive potential. Previously, we identified the histone demethylase KDM5A (lysine [K]-specific demethylase 5A), which demethylates histone H3 on Lys4 (H3K4), as a pRB-interacting protein counteracting pRB's role in promoting differentiation. Here we show that loss of Kdm5a restores differentiation through increasing mitochondrial respiration. This metabolic effect is both necessary and sufficient to induce the expression of a network of cell type-specific signaling and structural genes. Importantly, the regulatory functions of pRB in the cell cycle and differentiation are distinct because although restoring differentiation requires intact mitochondrial function, it does not necessitate cell cycle exit. Cells lacking Rb1 exhibit defective mitochondria and decreased oxygen consumption. Kdm5a is a direct repressor of metabolic regulatory genes, thus explaining the compensatory role of Kdm5a deletion in restoring mitochondrial function and differentiation. Significantly, activation of mitochondrial function by the mitochondrial biogenesis regulator Pgc-1α (peroxisome proliferator-activated receptor γ-coactivator 1α; also called PPARGC1A) a coactivator of the Kdm5a target genes, is sufficient to override the differentiation block. Overexpression of Pgc-1α, like KDM5A deletion, inhibits cell growth in RB-negative human cancer cell lines. The rescue of differentiation by loss of KDM5A or by activation of mitochondrial biogenesis reveals the switch to oxidative phosphorylation as an essential step in restoring differentiation and a less aggressive cancer phenotype. PMID:26314709

Downregulation of Pink1 influences mitochondrial fusion–fission machinery and sensitizes to neurotoxins in dopaminergic cells

PubMed Central

Rojas-Charry, Liliana; Cookson, Mark R.; Niño, Andrea; Arboleda, Humberto; Arboleda, Gonzalo

2016-01-01

It is now well established that mitochondria are organelles that, far from being static, are subject to a constant process of change. This process, which has been called mitochondrial dynamics, includes processes of both fusion and fission. Loss of Pink1 (PTEN-induced putative kinase 1) function is associated with early onset recessive Parkinson’s disease and it has been proposed that mitochondrial dynamics might be affected by loss of the mitochondrial kinase. Here, we report the effects of silencing Pink1 on mitochondrial fusion and fission events in dopaminergic neuron cell lines. Cells lacking Pink1 were more sensitive to cell death induced by C2-Ceramide, which inhibits proliferation and induces apoptosis. In the same cell lines, mitochondrial morphology was fragmented and this was enhanced by application of forskolin, which stimulates the cAMP pathway that phosphorylates Drp1 and thereby inactivates it. Cells lacking Pink1 had lower Drp1 and Mfn2 expression. Based on these data, we propose that Pink1 may exert a neuroprotective role in part by limiting mitochondrial fission. PMID:24792327

Prolonged Fasting Identifies Heat Shock Protein 10 as a Sirtuin 3 Substrate

PubMed Central

Lu, Zhongping; Chen, Yong; Aponte, Angel M.; Battaglia, Valentina; Gucek, Marjan; Sack, Michael N.

2015-01-01

Although Sirtuin 3 (SIRT3), a mitochondrially enriched deacetylase and activator of fat oxidation, is down-regulated in response to high fat feeding, the rate of fatty acid oxidation and mitochondrial protein acetylation are invariably enhanced in this dietary milieu. These paradoxical data implicate that additional acetylation modification-dependent levels of regulation may be operational under nutrient excess conditions. Because the heat shock protein (Hsp) Hsp10-Hsp60 chaperone complex mediates folding of the fatty acid oxidation enzyme medium-chain acyl-CoA dehydrogenase, we tested whether acetylation-dependent mitochondrial protein folding contributes to this regulatory discrepancy. We demonstrate that Hsp10 is a functional SIRT3 substrate and that, in response to prolonged fasting, SIRT3 levels modulate mitochondrial protein folding. Acetyl mutagenesis of Hsp10 lysine 56 alters Hsp10-Hsp60 binding, conformation, and protein folding. Consistent with Hsp10-Hsp60 regulation of fatty acid oxidation enzyme integrity, medium-chain acyl-CoA dehydrogenase activity and fat oxidation are elevated by Hsp10 acetylation. These data identify acetyl modification of Hsp10 as a nutrient-sensing regulatory node controlling mitochondrial protein folding and metabolic function. PMID:25505263

Activating Nrf-2 Signaling Depresses Unilateral Ureteral Obstruction-Evoked Mitochondrial Stress-Related Autophagy, Apoptosis and Pyroptosis in Kidney

PubMed Central

Chung, Shue Dong; Lai, Ting Yu; Chien, Chiang Ting; Yu, Hong Jen

2012-01-01

Exacerbated oxidative stress and inflammation may induce three types of programmed cell death, autophagy, apoptosis and pyroptosis in unilateral ureteral obstruction (UUO) kidney. Sulforaphane activating NF-E2-related nuclear factor erythroid-2 (Nrf-2) signaling may ameliorate UUO-induced renal damage. UUO was induced in the left kidney of female Wistar rats. The level of renal blood flow, cortical and medullary oxygen tension and reactive oxygen species (ROS) was evaluated. Fibrosis, ED-1 (macrophage/monocyte) infiltration, oxidative stress, autophagy, apoptosis and pyroptosis were evaluated by immunohistochemistry and Western blot in UUO kidneys. Effects of sulforaphane, an Nrf-2 activator, on Nrf-2- and mitochondrial stress-related proteins and renal injury were examined. UUO decreased renal blood flow and oxygen tension and increased renal ROS, 3-nitrotyrosine stain, ED-1 infiltration and fibrosis. Enhanced renal tubular Beclin-1 expression started at 4 h UUO and further enhanced at 3d UUO, whereas increased Atg-5-Atg12 and LC3-II expression were found at 3d UUO. Increased renal Bax/Bcl-2 ratio, caspase 3 and PARP fragments, apoptosis formation associated with increased caspase 1 and IL-1β expression for pyroptosis formation were started from 3d UUO. UUO reduced nuclear Nrf-2 translocation, increased cytosolic and inhibitory Nrf-2 expression, increased cytosolic Bax translocation to mitochondrial and enhanced mitochondrial Cytochrome c release into cytosol of the UUO kidneys. Sulforaphane significantly increased nuclear Nrf-2 translocation and decreased mitochondrial Bax translocation and Cytochrome c release into cytosol resulting in decreased renal injury. In conclusion, sulforaphane via activating Nrf-2 signaling preserved mitochondrial function and suppressed UUO-induced renal oxidative stress, inflammation, fibrosis, autophagy, apoptosis and pyroptosis. PMID:23071780

Enhanced expression of the DNA damage-inducible gene DIN7 results in increased mutagenesis of mitochondrial DNA in Saccharomyces cerevisiae.

PubMed

Koprowski, P; Fikus, M U; Dzierzbicki, P; Mieczkowski, P; Lazowska, J; Ciesla, Z

2003-08-01

We reported previously that the product of DIN7, a DNA damage-inducible gene of Saccharomyces cerevisiae, belongs to the XPG family of proteins, which are involved in DNA repair and replication. This family includes the S. cerevisiae protein Rad2p and its human homolog XPGC, Rad27p and its mammalian homolog FEN-1, and Exonuclease I (Exo I). Interestingly, Din7p is the only member of the XPG family which specifically functions in mitochondria. We reported previously that overexpression of DIN7 results in a mitochondrial mutator phenotype. In the present study we wished to test the hypothesis that this phenotype is dependent on the nuclease activity of Din7p. For this purpose, we constructed two alleles, din7-D78A and din7-D173A, which encode proteins in which highly conserved aspartates important for the nuclease activity of the XPG proteins have been replaced by alanines. Here, we report that overexpression of the mutant alleles, in contrast to DIN7, fails to increase the frequency of mitochondrial petite mutants or erythromycin-resistant (Er) mutants. Also, overproduction of din7-D78Ap does not result in destabilization of poly GT tracts in mitochondrial DNA (mtDNA), the phenotype observed in cells that overexpress Din7p. We also show that petite mutants induced by enhanced synthesis of wild-type Din7p exhibit gross rearrangements of mtDNA, and that this correlates with enhanced recombination within the mitochondrial cyt b gene. These results suggest that the stability of the mitochondrial genome of S. cerevisiae is modulated by the level of the nuclease Din7p.

Cyclophilin D Promotes Brain Mitochondrial F1FO ATP Synthase Dysfunction in Aging Mice

PubMed Central

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

Brain aging is the known strongest risk factor for Alzheimer’s disease (AD). In recent years, mitochondrial deficits have been proposed to be a common mechanism linking brain aging to AD. Therefore, to elucidate the causative mechanisms of mitochondrial dysfunction in aging brains is of paramount importance for our understanding of the pathogenesis of AD, in particular its sporadic form. Cyclophilin D (CypD) is a specific mitochondrial protein. Recent studies have shown that F1FO ATP synthase oligomycin sensitivity conferring protein (OSCP) is a binding partner of CypD. The interaction of CypD with OSCP modulates F1FO ATP synthase function and mediates mitochondrial permeability transition pore (mPTP) opening. Here, we have found that increased CypD expression, enhanced CypD/OSCP interaction, and selective loss of OSCP are prominent brain mitochondrial changes in aging mice. Along with these changes, brain mitochondria from the aging mice demonstrated decreased F1FO ATP synthase activity and defective F1FO complex coupling. In contrast, CypD deficient mice exhibited substantially mitigated brain mitochondrial F1FO ATP synthase dysfunction with relatively preserved mitochondrial function during aging. Interestingly, the aging-related OSCP loss was also dramatically attenuated by CypD depletion. Therefore, the simplest interpretation of this study is that CypD promotes F1FO ATP synthase dysfunction and the resultant mitochondrial deficits in aging brains. In addition, in view of CypD and F1FO ATP synthase alterations seen in AD brains, the results further suggest that CypD-mediated F1FO ATP synthase deregulation is a shared mechanism linking mitochondrial deficits in brain aging and AD. PMID:27834780

Cyclophilin D Promotes Brain Mitochondrial F1FO ATP Synthase Dysfunction in Aging Mice.

PubMed

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

Brain aging is the known strongest risk factor for Alzheimer's disease (AD). In recent years, mitochondrial deficits have been proposed to be a common mechanism linking brain aging to AD. Therefore, to elucidate the causative mechanisms of mitochondrial dysfunction in aging brains is of paramount importance for our understanding of the pathogenesis of AD, in particular its sporadic form. Cyclophilin D (CypD) is a specific mitochondrial protein. Recent studies have shown that F1FO ATP synthase oligomycin sensitivity conferring protein (OSCP) is a binding partner of CypD. The interaction of CypD with OSCP modulates F1FO ATP synthase function and mediates mitochondrial permeability transition pore (mPTP) opening. Here, we have found that increased CypD expression, enhanced CypD/OSCP interaction, and selective loss of OSCP are prominent brain mitochondrial changes in aging mice. Along with these changes, brain mitochondria from the aging mice demonstrated decreased F1FO ATP synthase activity and defective F1FO complex coupling. In contrast, CypD deficient mice exhibited substantially mitigated brain mitochondrial F1FO ATP synthase dysfunction with relatively preserved mitochondrial function during aging. Interestingly, the aging-related OSCP loss was also dramatically attenuated by CypD depletion. Therefore, the simplest interpretation of this study is that CypD promotes F1FO ATP synthase dysfunction and the resultant mitochondrial deficits in aging brains. In addition, in view of CypD and F1FO ATP synthase alterations seen in AD brains, the results further suggest that CypD-mediated F1FO ATP synthase deregulation is a shared mechanism linking mitochondrial deficits in brain aging and AD.

Mitochondrial dysfunction enhances cisplatin resistance in human gastric cancer cells via the ROS-activated GCN2-eIF2α-ATF4-xCT pathway

PubMed Central

Wang, Sheng-Fan; Chen, Meng-Shian; Chou, Yueh-Ching; Ueng, Yune-Fang; Yin, Pen-Hui; Yeh, Tien-Shun; Lee, Hsin-Chen

2016-01-01

Mitochondrial DNA mutations and defects in mitochondrial enzymes have been identified in gastric cancers, and they might contribute to cancer progression. In previous studies, mitochondrial dysfunction was induced by oligomycin-enhanced chemoresistance to cisplatin. Herein, we dissected the regulatory mechanism for mitochondrial dysfunction-enhanced cisplatin resistance in human gastric cancer cells. Repeated cisplatin treatment-induced cisplatin-resistant cells exhibited high SLC7A11 (xCT) expression, and xCT inhibitors (sulfasalazine or erastin), xCT siRNA, or a GSH synthesis inhibitor (buthionine sulphoximine, BSO) could sensitize these cells to cisplatin. Clinically, the high expression of xCT was associated with a poorer prognosis for gastric cancer patients under adjuvant chemotherapy. Moreover, we found that mitochondrial dysfunction enhanced cisplatin resistance and up-regulated xCT expression, as well as intracellular glutathione (GSH). The xCT inhibitors, siRNA against xCT or BSO decreased mitochondrial dysfunction-enhanced cisplatin resistance. We further demonstrated that the upregulation of the eIF2α-ATF4 pathway contributed to mitochondrial dysfunction-induced xCT expression, and activated eIF2α kinase GCN2, but not PERK, stimulated the eIF2α-ATF4-xCT pathway in response to mitochondrial dysfunction-increased reactive oxygen species (ROS) levels. In conclusion, our results suggested that the ROS-activated GCN2-eIF2α-ATF4-xCT pathway might contribute to mitochondrial dysfunction-enhanced cisplatin resistance and could be a potential target for gastric cancer therapy. PMID:27708226

Mitochondrial dysfunction enhances cisplatin resistance in human gastric cancer cells via the ROS-activated GCN2-eIF2α-ATF4-xCT pathway.

PubMed

Wang, Sheng-Fan; Chen, Meng-Shian; Chou, Yueh-Ching; Ueng, Yune-Fang; Yin, Pen-Hui; Yeh, Tien-Shun; Lee, Hsin-Chen

2016-11-08

Mitochondrial DNA mutations and defects in mitochondrial enzymes have been identified in gastric cancers, and they might contribute to cancer progression. In previous studies, mitochondrial dysfunction was induced by oligomycin-enhanced chemoresistance to cisplatin. Herein, we dissected the regulatory mechanism for mitochondrial dysfunction-enhanced cisplatin resistance in human gastric cancer cells. Repeated cisplatin treatment-induced cisplatin-resistant cells exhibited high SLC7A11 (xCT) expression, and xCT inhibitors (sulfasalazine or erastin), xCT siRNA, or a GSH synthesis inhibitor (buthionine sulphoximine, BSO) could sensitize these cells to cisplatin. Clinically, the high expression of xCT was associated with a poorer prognosis for gastric cancer patients under adjuvant chemotherapy. Moreover, we found that mitochondrial dysfunction enhanced cisplatin resistance and up-regulated xCT expression, as well as intracellular glutathione (GSH). The xCT inhibitors, siRNA against xCT or BSO decreased mitochondrial dysfunction-enhanced cisplatin resistance. We further demonstrated that the upregulation of the eIF2α-ATF4 pathway contributed to mitochondrial dysfunction-induced xCT expression, and activated eIF2α kinase GCN2, but not PERK, stimulated the eIF2α-ATF4-xCT pathway in response to mitochondrial dysfunction-increased reactive oxygen species (ROS) levels. In conclusion, our results suggested that the ROS-activated GCN2-eIF2α-ATF4-xCT pathway might contribute to mitochondrial dysfunction-enhanced cisplatin resistance and could be a potential target for gastric cancer therapy.

Mitochondrial respiratory complex I probed by delayed luminescence spectroscopy

NASA Astrophysics Data System (ADS)

Baran, Irina; Ionescu, Diana; Privitera, Simona; Scordino, Agata; Mocanu, Maria Magdalena; Musumeci, Francesco; Grasso, Rosaria; Gulino, Marisa; Iftime, Adrian; Tofolean, Ioana Teodora; Garaiman, Alexandru; Goicea, Alexandru; Irimia, Ruxandra; Dimancea, Alexandru; Ganea, Constanta

2013-12-01

The role of mitochondrial complex I in ultraweak photon-induced delayed photon emission [delayed luminescence (DL)] of human leukemia Jurkat T cells was probed by using complex I targeting agents like rotenone, menadione, and quercetin. Rotenone, a complex I-specific inhibitor, dose-dependently increased the mitochondrial level of reduced nicotinamide adenine dinucleotide (NADH), decreased clonogenic survival, and induced apoptosis. A strong correlation was found between the mitochondrial levels of NADH and oxidized flavin mononucleotide (FMNox) in rotenone-, menadione- and quercetin-treated cells. Rotenone enhanced DL dose-dependently, whereas quercetin and menadione inhibited DL as well as NADH or FMNox. Collectively, the data suggest that DL of Jurkat cells originates mainly from mitochondrial complex I, which functions predominantly as a dimer and less frequently as a tetramer. In individual monomers, both pairs of pyridine nucleotide (NADH/reduced nicotinamide adenine dinucleotide phosphate) sites and flavin (FMN-a/FMN-b) sites appear to bind cooperatively their specific ligands. Enhancement of delayed red-light emission by rotenone suggests that the mean time for one-electron reduction of ubiquinone or FMN-a by the terminal Fe/S center (N2) is 20 or 284 μs, respectively. All these findings suggest that DL spectroscopy could be used as a reliable, sensitive, and robust technique to probe electron flow within complex I in situ.

Continued clearance of apoptotic cells critically depends on the phagocyte Ucp2 protein.

PubMed

Park, Daeho; Han, Claudia Z; Elliott, Michael R; Kinchen, Jason M; Trampont, Paul C; Das, Soumita; Collins, Sheila; Lysiak, Jeffrey J; Hoehn, Kyle L; Ravichandran, Kodi S

2011-08-21

Rapid and efficient removal of apoptotic cells by phagocytes is important during development, tissue homeostasis and in immune responses. Efficient clearance depends on the capacity of a single phagocyte to ingest multiple apoptotic cells successively, and to process the corpse-derived cellular material. However, the factors that influence continued clearance by phagocytes are not known. Here we show that the mitochondrial membrane potential of the phagocyte critically controls engulfment capacity, with lower potential enhancing engulfment and vice versa. The mitochondrial membrane protein Ucp2, which acts to lower the mitochondrial membrane potential, was upregulated in phagocytes engulfing apoptotic cells. Loss of Ucp2 reduced phagocytic capacity, whereas Ucp2 overexpression enhanced engulfment. Mutational and pharmacological studies indicated a direct role for Ucp2-mediated mitochondrial function in phagocytosis. Macrophages from Ucp2-deficient mice were impaired in phagocytosis in vitro, and Ucp2-deficient mice showed profound in vivo defects in clearing dying cells in the thymus and testes. Collectively, these data indicate that mitochondrial membrane potential and Ucp2 are key molecular determinants of apoptotic cell clearance. As Ucp2 is linked to metabolic diseases and atherosclerosis, this newly discovered role for Ucp2 in apoptotic cell clearance has implications for the complex aetiology and pathogenesis of these diseases.

Silencing of mitochondrial NADP{sup +}-dependent isocitrate dehydrogenase gene enhances glioma radiosensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Sung Youl; Yoo, Young Hyun; Park, Jeen-Woo, E-mail: parkjw@knu.ac.kr

Highlights: •Silencing of the IDPm gene enhances IR-induced autophagy in glioma cells. •Autophagy inhibition augmented apoptosis of irradiated glioma cells. •Results offer a redox-active therapeutic strategy for the treatment of cancer. -- Abstract: Reactive oxygen species (ROS) levels are elevated in organisms that have been exposed to ionizing radiation and are protagonists in the induction of cell death. Recently, we demonstrated that the control of mitochondrial redox balance and the cellular defense against oxidative damage are primary functions of mitochondrial NADP{sup +}-dependent isocitrate dehydrogenase (IDPm) via the supply of NADPH for antioxidant systems. In the present study, we report anmore » autophagic response to ionizing radiation in A172 glioma cells transfected with small interfering RNA (siRNA) targeting the IDPm gene. Autophagy in A172 transfectant cells was associated with enhanced autophagolysosome formation and GFP–LC3 punctuation/aggregation. Furthermore, we found that the inhibition of autophagy by chloroquine augmented apoptotic cell death of irradiated A172 cells transfected with IDPm siRNA. Taken together, our data suggest that autophagy functions as a survival mechanism in A172 cells against ionizing radiation-induced apoptosis and the sensitizing effect of IDPm siRNA and autophagy inhibitor on the ionizing radiation-induced apoptotic cell death of glioma cells offers a novel redox-active therapeutic strategy for the treatment of cancer.« less

Role of heteromeric gap junctions in the cytotoxicity of cisplatin.

PubMed

Tong, Xuhui; Dong, Shuying; Yu, Meiling; Wang, Qin; Tao, Liang

2013-08-09

In several systems, the presence of gap junctions made of a single connexin has been shown to enhance the cytotoxicity of cisplatin. However, most gap junction channels in vivo appear to be heteromeric (composed of more than one connexin isoform). Here we explore in HeLa cells the cytotoxicity to cisplatin that is enhanced by heteromeric gap junctions composed of Cx26 and Cx32, which have been shown to be more selective among biological permeants than the corresponding homomeric channels. We found that survival and subsequent proliferation of cells exposed to cisplatin were substantially reduced when gap junctions were present than when there were no gap junctions. Functional inhibition of gap junctions by oleamide enhanced survival/proliferation, and enhancement of gap junctions by retinoic acid decreased survival/proliferation. These effects occurred only in high density cultures, and the treatments were without effect when there was no opportunity for gap junction formation. The presence of functional gap junctions enhanced apoptosis as reflected in markers of both early-stage and late-stage apoptosis. Furthermore, analysis of caspases 3, 8 and 9 showed that functional gap junctions specifically induced apoptosis by the mitochondrial pathway. These results demonstrate that heteromeric Cx26/Cx32 gap junctions increase the cytotoxicity of cisplatin by induction of apoptosis via the mitochondrial pathway. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

α-Lactalbumin-oleic acid complex kills tumor cells by inducing excess energy metabolism but inhibiting mRNA expression of the related enzymes.

PubMed

Fang, B; Zhang, M; Ge, K S; Xing, H Z; Ren, F Z

2018-06-01

Previous studies have demonstrated that the anti-tumor α-lactalbumin-oleic acid complex (α-LA-OA) may target the glycolysis of tumor cells. However, few data are available regarding the effects of α-LA-OA on energy metabolism. In this study, we measured glycolysis and mitochondrial functions in HeLa cells in response to α-LA-OA using the XF flux analyzer (Seahorse Bioscience, North Billerica, MA). The gene expression of enzymes involved in glycolysis, tricarboxylic acid cycle, electron transfer chain, and ATP synthesis were also evaluated. Our results show that α-LA-OA significantly enhanced the basal glycolysis and glycolytic capacity. Mitochondrial oxidative phosphorylation, including the basal respiration, maximal respiration, spare respiratory capacity and ATP production were also improved in response to α-LA-OA. The enhanced mitochondrial functions maybe partly due to the increased capacity of utilizing fatty acids and glutamine as the substrate. However, the gene expressions of pyruvate kinase M2, lactate dehydrogenase A, aconitate hydratase, and isocitrate dehydrogenase 1 were inhibited, suggesting an insufficient ability for the glycolysis process and the tricarboxylic acid cycle. The increased expression of acetyl-coenzyme A acyltransferase 2, a central enzyme involved in the β-oxidation of fatty acids, would enhance the unbalance due to the decreased expression of electron transfer flavoprotein β subunit, which acts as the electron acceptor. These results indicated that α-LA-OA may induce oxidative stress due to conditions in which the ATP production is exceeding the energy demand. Our results may help clarify the mechanism of apoptosis induced by reactive oxygen species and mitochondrial destruction. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

PGC-1α-Dependent Mitochondrial Adaptation Is Necessary to Sustain IL-2-Induced Activities in Human NK Cells

PubMed Central

Jara, Claudia; Ibañez, Jorge; Ahumada, Viviana; Acuña-Castillo, Claudio; Martin, Adrian; Córdova, Alexandra

2016-01-01

Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in antitumor defense reactions. NK cell effector functions are critically dependent on cytokines and metabolic activity. Among various cytokines modulating NK cell function, interleukin-2 (IL-2) can induce a more potent cytotoxic activity defined as lymphokine activated killer activity (LAK). Our aim was to determine if IL-2 induces changes at the mitochondrial level in NK cells to support the bioenergetic demand for performing this enhanced cytotoxic activity more efficiently. Purified human NK cells were cultured with high IL-2 concentrations to develop LAK activity, which was assessed by the ability of NK cells to lyse NK-resistant Daudi cells. Here we show that, after 72 h of culture of purified human NK cells with enough IL-2 to induce LAK activity, both the mitochondrial mass and the mitochondrial membrane potential increased in a PGC-1α-dependent manner. In addition, oligomycin, an inhibitor of ATP synthase, inhibited IL-2-induced LAK activity at 48 and 72 h of culture. Moreover, the secretion of IFN-γ from NK cells with LAK activity was also partially dependent on PGC-1α expression. These results indicate that PGC-1α plays a crucial role in regulating mitochondrial function involved in the maintenance of LAK activity in human NK cells stimulated with IL-2. PMID:27413259

PGC-1α-Dependent Mitochondrial Adaptation Is Necessary to Sustain IL-2-Induced Activities in Human NK Cells.

PubMed

Miranda, Dante; Jara, Claudia; Ibañez, Jorge; Ahumada, Viviana; Acuña-Castillo, Claudio; Martin, Adrian; Córdova, Alexandra; Montoya, Margarita

2016-01-01

Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in antitumor defense reactions. NK cell effector functions are critically dependent on cytokines and metabolic activity. Among various cytokines modulating NK cell function, interleukin-2 (IL-2) can induce a more potent cytotoxic activity defined as lymphokine activated killer activity (LAK). Our aim was to determine if IL-2 induces changes at the mitochondrial level in NK cells to support the bioenergetic demand for performing this enhanced cytotoxic activity more efficiently. Purified human NK cells were cultured with high IL-2 concentrations to develop LAK activity, which was assessed by the ability of NK cells to lyse NK-resistant Daudi cells. Here we show that, after 72 h of culture of purified human NK cells with enough IL-2 to induce LAK activity, both the mitochondrial mass and the mitochondrial membrane potential increased in a PGC-1α-dependent manner. In addition, oligomycin, an inhibitor of ATP synthase, inhibited IL-2-induced LAK activity at 48 and 72 h of culture. Moreover, the secretion of IFN-γ from NK cells with LAK activity was also partially dependent on PGC-1α expression. These results indicate that PGC-1α plays a crucial role in regulating mitochondrial function involved in the maintenance of LAK activity in human NK cells stimulated with IL-2.

Curcumin prevents mitochondrial dysfunction in the brain of the senescence-accelerated mouse-prone 8.

PubMed

Eckert, Gunter P; Schiborr, Christina; Hagl, Stephanie; Abdel-Kader, Reham; Müller, Walter E; Rimbach, Gerald; Frank, Jan

2013-04-01

The aging brain suffers mitochondrial dysfunction and a reduced availability of energy in the form of ATP, which in turn may cause or promote the decline in cognitive, sensory, and motor function observed with advancing age. There is a need for animal models that display some of the pathological features of human brain aging in order to study their prevention by e.g. dietary factors. We thus investigated the suitability of the fast-aging senescence-accelerated mouse-prone 8 (SAMP8) strain and its normally aging control senescence-accelerated mouse-resistant 1 (SAMR1) as a model for the age-dependent changes in mitochondrial function in the brain. To this end, 2-months old male SAMR1 (n=10) and SAMP8 mice (n=7) were fed a Western type diet (control groups) for 5months and one group of SAMP8 mice (n=6) was fed an identical diet fortified with 500mg curcumin per kg. Dissociated brain cells and brain tissue homogenates were analyzed for malondialdehyde, heme oxygenase-1 mRNA, mitochondrial membrane potential (MMP), ATP concentrations, protein levels of mitochondrial marker proteins for mitochondrial membranes (TIMM, TOMM), the mitochondrial permeability transition pore (ANT1, VDAC1, TSPO), respiration complexes, and fission and fusion (Fis, Opa1, Mfn1, Drp1). Dissociated brain cells isolated from SAMP8 mice showed significantly reduced MMP and ATP levels, probably due to significantly diminished complex V protein expression, and increased expression of TSPO. Fission and fusion marker proteins indicate enhanced mitochondrial fission in brains of SAMP8 mice. Treatment of SAMP8 mice with curcumin improved MMP and ATP and restored mitochondrial fusion, probably by up-regulating nuclear factor PGC1α protein expression. In conclusion, SAMP8 compared to SAMR1 mice are a suitable model to study age-dependent changes in mitochondrial function and curcumin emerges as a promising nutraceutical for the prevention of neurodegenerative diseases that are accompanied or caused by mitochondrial dysfunction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ganoderma lucidum ameliorate mitochondrial damage in isoproterenol-induced myocardial infarction in rats by enhancing the activities of TCA cycle enzymes and respiratory chain complexes.

PubMed

Sudheesh, N P; Ajith, T A; Janardhanan, K K

2013-04-30

Decreased mitochondrial function has been suggested to be one of the important pathological events in isoproterenol (ISO)-induced cardiotoxicity. In this communication, we have evaluated the protective effect of Ganoderma lucidum against ISO induced cardiac toxicity and mitochondrial dysfunction. Cardiac toxicity was assessed by determining the activities of creatine kinase (CK) and lactate dehydrogenases (LDH) after subcutaneous injection of ISO (85 mg/kg) at an interval of 24h for 2 days. The animals were sacrificed 24h after last ISO administration. G. lucidum (100 and 250 mg/kg, p.o.) was given to the rats once daily for 15 days prior to the ISO challenge. Similarly, α-Tocopherol (100mg/kg, p.o) was kept as the standard. To assess the extent of cardiac mitochondrial damage, the activities of Krebs cycle dehydrogenases and mitochondrial complexes I, II, III, and IV as well as the level of ROS and mitochondrial membrane potential (ΔΨmt) were evaluated. Administration of G. lucidum and α-tocopherol significantly protected the elevated activities of CK and LDH. Further, the activities of mitochondrial enzymes and the level of ΔΨmt were significantly enhanced and the level of ROS was significantly declined in the G. lucidum and α-tocopherol treatments. The present study concluded that the cardiac mitochondrial enzymes are markedly declined by the ISO challenge and the administration G. lucidum and α-Tocopherol significantly protected mitochondria by preventing the decline of antioxidant status and ΔΨmt or by directly scavenging the free radicals. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Mitochondrial vulnerability and increased susceptibility to nutrient-induced cytotoxicity in fibroblasts from leigh syndrome French canadian patients.

PubMed

Burelle, Yan; Bemeur, Chantal; Rivard, Marie-Eve; Thompson Legault, Julie; Boucher, Gabrielle; Morin, Charles; Coderre, Lise; Des Rosiers, Christine

2015-01-01

Mutations in LRPPRC are responsible for the French Canadian variant of Leigh Syndrome (LSFC), a severe disorder characterized biochemically by a tissue-specific deficiency of cytochrome c oxidase (COX) and clinically by the occurrence of severe and deadly acidotic crises. Factors that precipitate these crises remain unclear. To better understand the physiopathology and identify potential treatments, we performed a comprehensive analysis of mitochondrial function in LSFC and control fibroblasts. Furthermore, we have used this cell-based model to screen for conditions that promote premature cell death in LSFC cells and test the protective effect of ten interventions targeting well-defined aspects of mitochondrial function. We show that, despite maintaining normal ATP levels, LSFC fibroblasts present several mitochondrial functional abnormalities under normal baseline conditions, which likely impair their capacity to respond to stress. This includes mitochondrial network fragmentation, impaired oxidative phosphorylation capacity, lower membrane potential, increased sensitivity to Ca2+-induced permeability transition, but no changes in reactive oxygen species production. We also show that LSFC fibroblasts display enhanced susceptibility to cell death when exposed to palmitate, an effect that is potentiated by high lactate, while high glucose or acidosis alone or in combination were neutral. Furthermore, we demonstrate that compounds that are known to promote flux through the electron transport chain independent of phosphorylation (methylene blue, dinitrophenol), or modulate fatty acid (L-carnitine) or Krebs cycle metabolism (propionate) are protective, while antioxidants (idebenone, N-acetyl cysteine, resveratrol) exacerbate palmitate plus lactate-induced cell death. Collectively, beyond highlighting multiple alterations in mitochondrial function and increased susceptibility to nutrient-induced cytotoxicity in LSFC fibroblasts, these results raise questions about the nature of the diets, particularly excess fat intake, as well as on the use of antioxidants in patients with LSFC and, possibly, other COX defects.

Protective effects of dietary avocado oil on impaired electron transport chain function and exacerbated oxidative stress in liver mitochondria from diabetic rats.

PubMed

Ortiz-Avila, Omar; Gallegos-Corona, Marco Alonso; Sánchez-Briones, Luis Alberto; Calderón-Cortés, Elizabeth; Montoya-Pérez, Rocío; Rodriguez-Orozco, Alain R; Campos-García, Jesús; Saavedra-Molina, Alfredo; Mejía-Zepeda, Ricardo; Cortés-Rojo, Christian

2015-08-01

Electron transport chain (ETC) dysfunction, excessive ROS generation and lipid peroxidation are hallmarks of mitochondrial injury in the diabetic liver, with these alterations also playing a role in the development of non-alcoholic fatty liver disease (NAFLD). Enhanced mitochondrial sensitivity to lipid peroxidation during diabetes has been also associated to augmented content of C22:6 in membrane phospholipids. Thus, we aimed to test whether avocado oil, a rich source of C18:1 and antioxidants, attenuates the deleterious effects of diabetes on oxidative status of liver mitochondria by decreasing unsaturation of acyl chains of membrane lipids and/or by improving ETC functionality and decreasing ROS generation. Streptozocin-induced diabetes elicited a noticeable increase in the content of C22:6, leading to augmented mitochondrial peroxidizability index and higher levels of lipid peroxidation. Mitochondrial respiration and complex I activity were impaired in diabetic rats with a concomitant increase in ROS generation using a complex I substrate. This was associated to a more oxidized state of glutathione, All these alterations were prevented by avocado oil except by the changes in mitochondrial fatty acid composition. Avocado oil did not prevented hyperglycemia and polyphagia although did normalized hyperlipidemia. Neither diabetes nor avocado oil induced steatosis. These results suggest that avocado oil improves mitochondrial ETC function by attenuating the deleterious effects of oxidative stress in the liver of diabetic rats independently of a hypoglycemic effect or by modifying the fatty acid composition of mitochondrial membranes. These findings might have also significant implications in the progression of NAFLD in experimental models of steatosis.

Air pollution induces enhanced mitochondrial oxidative stress in cystic fibrosis airway epithelium.

PubMed

Kamdar, O; Le, Wei; Zhang, J; Ghio, A J; Rosen, G D; Upadhyay, D

2008-10-29

We studied the effects of airborne particulate matters (PM) on cystic fibrosis (CF) epithelium. We noted that PM enhanced human CF bronchial epithelial apoptosis, activated caspase-9 and PARP-1; and reduced mitochondrial membrane potential. Mitochondrial inhibitors (4,4-diisothiocyanatostilbene-2,2'disulfonic acid, rotenone and thenoyltrifluoroacetone) blocked PM-induced generation of reactive oxygen species and apoptosis. PM upregulated pro-apoptotic Bad, Bax, p53 and p21; and enhanced mitochondrial localization of Bax. The anti-apoptotic Bcl-2, Bcl-xl, Mcl-1 and Xiap remained unchanged; however, overexpression of Bcl-xl blocked PM-induced apoptosis. Accordingly, we provide the evidence that PM enhances oxidative stress and mitochondrial signaling mediated apoptosis via the modulation of Bcl family proteins in CF.

ALDH2 restores exhaustive exercise-induced mitochondrial dysfunction in skeletal muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Qiuping; Zheng, Jianheng; Qiu, Jun

Background: Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is highly expressed in heart and skeletal muscles, and is the major enzyme that metabolizes acetaldehyde and toxic aldehydes. The cardioprotective effects of ALDH2 during cardiac ischemia/reperfusion injury have been recognized. However, less is known about the function of ALDH2 in skeletal muscle. This study was designed to evaluate the effect of ALDH2 on exhaustive exercise-induced skeletal muscle injury. Methods: We created transgenic mice expressing ALDH2 in skeletal muscles. Male wild-type C57/BL6 (WT) and ALDH2 transgenic mice (ALDH2-Tg), 8-weeks old, were challenged with exhaustive exercise for 1 week to induce skeletal muscle injury. Animalsmore » were sacrificed 24 h post-exercise and muscle tissue was excised. Results: ALDH2-Tg mice displayed significantly increased treadmill exercise capacity compared to WT mice. Exhaustive exercise caused an increase in mRNA levels of the muscle atrophy markers, Atrogin-1 and MuRF1, and reduced mitochondrial biogenesis and fusion in WT skeletal muscles; these effects were attenuated in ALDH2-Tg mice. Exhaustive exercise also enhanced mitochondrial autophagy pathway activity, including increased conversion of LC3-I to LC3-II and greater expression of Beclin1 and Bnip3; the effects of which were mitigated by ALDH2 overexpression. In addition, ALDH2-Tg reversed the increase of an oxidative stress biomarker (4-hydroxynonenal) and decreased levels of mitochondrial antioxidant proteins, including manganese superoxide dismutase and NAD(P)H:quinone oxidoreductase 1, in skeletal muscle induced by exhaustive exercise. Conclusion: ALDH2 may reverse skeletal muscle mitochondrial dysfunction due to exhaustive exercise by regulating mitochondria dynamic remodeling and enhancing the quality of mitochondria. - Highlights: • Skeletal muscle ALDH2 expression and activity declines during exhaustive exercise. • ALDH2 overexpression enhances physical performance and restores muscle atrophy. • ALDH2 overexpression attenuates exercise-induced mitochondrial oxidative stress.« less

Protein kinase C epsilon regulates mitochondrial pools of Nampt and NAD following resveratrol and ischemic preconditioning in the rat cortex

PubMed Central

Morris-Blanco, Kahlilia C; Cohan, Charles H; Neumann, Jake T; Sick, Thomas J; Perez-Pinzon, Miguel A

2014-01-01

Preserving mitochondrial pools of nicotinamide adenine dinucleotide (NAD) or nicotinamide phosphoribosyltransferase (Nampt), an enzyme involved in NAD production, maintains mitochondrial function and confers neuroprotection after ischemic stress. However, the mechanisms involved in regulating mitochondrial-localized Nampt or NAD have not been defined. In this study, we investigated the roles of protein kinase C epsilon (PKCɛ) and AMP-activated protein kinase (AMPK) in regulating mitochondrial pools of Nampt and NAD after resveratrol or ischemic preconditioning (IPC) in the cortex and in primary neuronal-glial cortical cultures. Using the specific PKCɛ agonist ψɛRACK, we found that PKCɛ induced robust activation of AMPK in vitro and in vivo and that AMPK was required for PKCɛ-mediated ischemic neuroprotection. In purified mitochondrial fractions, PKCɛ enhanced Nampt levels in an AMPK-dependent manner and was required for increased mitochondrial Nampt after IPC or resveratrol treatment. Analysis of intrinsic NAD autofluorescence using two-photon microscopy revealed that PKCɛ modulated NAD in the mitochondrial fraction. Further assessments of mitochondrial NAD concentrations showed that PKCɛ has a key role in regulating the mitochondrial NAD+/nicotinamide adenine dinucleotide reduced (NADH) ratio after IPC and resveratrol treatment in an AMPK- and Nampt-dependent manner. These findings indicate that PKCɛ is critical to increase or maintain mitochondrial Nampt and NAD after pathways of ischemic neuroprotection in the brain. PMID:24667915

An Actin-Dependent Step in Mitochondrial Fission Mediated by the ER-Associated Formin INF2

PubMed Central

Korobova, Farida; Ramabhadran, Vinay; Higgs, Henry N.

2013-01-01

Mitochondrial fission is fundamentally important to cellular physiology. The dynamin-related protein Drp1 mediates fission, and interaction between mitochondrion and endoplasmic reticulum (ER) enhances fission. However, the mechanism for Drp1 recruitment to mitochondria is unclear, although previous results implicate actin involvement. Here, we found that actin polymerization through ER-localized inverted formin 2 (INF2) was required for efficient mitochondrial fission in mammalian cells. INF2 functioned upstream of Drp1. Actin filaments appeared to accumulate between mitochondria and INF2-enriched ER membranes at constriction sites. Thus, INF2-induced actin filaments may drive initial mitochondrial constriction, which allows Drp1-driven secondary constriction. Because INF2 mutations can lead to Charcot-Marie-Tooth disease, our results provide a potential cellular mechanism for this disease state. PMID:23349293

Inhibition of mTOR Prevents ROS Production Initiated by Ethidium Bromide-Induced Mitochondrial DNA Depletion

PubMed Central

Nacarelli, Timothy; Azar, Ashley; Sell, Christian

2014-01-01

The regulation of mitochondrial mass and DNA content involves a complex interaction between mitochondrial DNA replication machinery, functional components of the electron transport chain, selective clearance of mitochondria, and nuclear gene expression. In order to gain insight into cellular responses to mitochondrial stress, we treated human diploid fibroblasts with ethidium bromide at concentrations that induced loss of mitochondrial DNA over a period of 7 days. The decrease in mitochondrial DNA was accompanied by a reduction in steady state levels of the mitochondrial DNA binding protein, TFAM, a reduction in several electron transport chain protein levels, increased mitochondrial and total cellular ROS, and activation of p38 MAPK. However, there was an increase in mitochondrial mass and voltage dependent anion channel levels. In addition, mechanistic target of rapamycin (mTOR) activity, as judged by p70S6K targets, was decreased while steady state levels of p62/SQSTM1 and Parkin were increased. Treatment of cells with rapamycin created a situation in which cells were better able to adapt to the mitochondrial dysfunction, resulting in decreased ROS and increased cell viability but did not prevent the reduction in mitochondrial DNA. These effects may be due to a more efficient flux through the electron transport chain, increased autophagy, or enhanced AKT signaling, coupled with a reduced growth rate. Together, the results suggest that mTOR activity is affected by mitochondrial stress, which may be part of the retrograde signal system required for normal mitochondrial homeostasis. PMID:25104948

Genetically enhancing mitochondrial antioxidant activity improves muscle function in aging

PubMed Central

Umanskaya, Alisa; Santulli, Gaetano; Andersson, Daniel C.; Reiken, Steven R.; Marks, Andrew R.

2014-01-01

Age-related skeletal muscle dysfunction is a leading cause of morbidity that affects up to half the population aged 80 or greater. Here we tested the effects of increased mitochondrial antioxidant activity on age-dependent skeletal muscle dysfunction using transgenic mice with targeted overexpression of the human catalase gene to mitochondria (MCat mice). Aged MCat mice exhibited improved voluntary exercise, increased skeletal muscle specific force and tetanic Ca2+ transients, decreased intracellular Ca2+ leak and increased sarcoplasmic reticulum (SR) Ca2+ load compared with age-matched wild type (WT) littermates. Furthermore, ryanodine receptor 1 (the sarcoplasmic reticulum Ca2+ release channel required for skeletal muscle contraction; RyR1) from aged MCat mice was less oxidized, depleted of the channel stabilizing subunit, calstabin1, and displayed increased single channel open probability (Po). Overall, these data indicate a direct role for mitochondrial free radicals in promoting the pathological intracellular Ca2+ leak that underlies age-dependent loss of skeletal muscle function. This study harbors implications for the development of novel therapeutic strategies, including mitochondria-targeted antioxidants for treatment of mitochondrial myopathies and other healthspan-limiting disorders. PMID:25288763

A TSPO ligand prevents mitochondrial sterol accumulation and dysfunction during myocardial ischemia-reperfusion in hypercholesterolemic rats.

PubMed

Musman, Julien; Paradis, Stéphanie; Panel, Mathieu; Pons, Sandrine; Barau, Caroline; Caccia, Claudio; Leoni, Valerio; Ghaleh, Bijan; Morin, Didier

2017-10-15

A major cause of cell death during myocardial ischemia-reperfusion is mitochondrial dysfunction. We previously showed that the reperfusion of an ischemic myocardium was associated with an accumulation of cholesterol into mitochondria and a concomitant strong generation of auto-oxidized oxysterols. The inhibition of mitochondrial accumulation of cholesterol abolished the formation of oxysterols and prevented mitochondrial injury at reperfusion. The aim of this study was to investigate the impact of hypercholesterolemia on sterol and oxysterol accumulation in rat cardiac cytosols and mitochondria and to analyse the effect of the translocator protein ligand 4'-chlorodiazepam on this accumulation and mitochondrial function. Hypercholesterolemic ZDF fa/fa rats or normocholesterolemic lean rats were submitted to 30min of coronary artery occlusion followed by 15min reperfusion where cardiac cytosols and mitochondria were isolated. Hypercholesterolemia increased the cellular cardiac concentrations of cholesterol, cholesterol precursors and oxysterols both in cytosol and mitochondria in non-ischemic conditions. It also amplified the accumulation of all these compounds in cardiac cells and the alteration of mitochondrial function with ischemia-reperfusion. Administration of 4'-chlorodiazepam to ZDF fa/fa rats had no effect on the enhancement of sterols and oxysterols observed in the cytosols but inhibited cholesterol transfer to the mitochondria. It also alleviated the mitochondrial accumulation of all the investigated sterols and oxysterols. This was associated with a restoration of oxidative phosphorylation and a prevention of mitochondrial transition pore opening. The inhibition of cholesterol accumulation with TSPO ligands represents an interesting strategy to protect the mitochondria during ischemia-reperfusion in hypercholesterolemic conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

RecA-Dependent DNA Repair Results in Increased Heteroplasmy of the Arabidopsis Mitochondrial Genome1[C][W

PubMed Central

Miller-Messmer, Marie; Kühn, Kristina; Bichara, Marc; Le Ret, Monique; Imbault, Patrice; Gualberto, José M.

2012-01-01

Plant mitochondria have very active DNA recombination activities that are responsible for its plastic structures and that should be involved in the repair of double-strand breaks in the mitochondrial genome. Little is still known on plant mitochondrial DNA repair, but repair by recombination is believed to be a major determinant in the rapid evolution of plant mitochondrial genomes. In flowering plants, mitochondria possess at least two eubacteria-type RecA proteins that should be core components of the mitochondrial repair mechanisms. We have performed functional analyses of the two Arabidopsis (Arabidopsis thaliana) mitochondrial RecAs (RECA2 and RECA3) to assess their potential roles in recombination-dependent repair. Heterologous expression in Escherichia coli revealed that RECA2 and RECA3 have overlapping as well as specific activities that allow them to partially complement bacterial repair pathways. RECA2 and RECA3 have similar patterns of expression, and mutants of either display the same molecular phenotypes of increased recombination between intermediate-size repeats, thus suggesting that they act in the same recombination pathways. However, RECA2 is essential past the seedling stage and should have additional important functions. Treatment of plants with several DNA-damaging drugs further showed that RECA3 is required for different recombination-dependent repair pathways that significantly contribute to plant fitness under stress. Replication repair of double-strand breaks results in the accumulation of crossovers that increase the heteroplasmic state of the mitochondrial DNA. It was shown that these are transmitted to the plant progeny, enhancing the potential for mitochondrial genome evolution. PMID:22415515

SIRT3 aggravates metformin-induced energy stress and apoptosis in ovarian cancer cells.

PubMed

Wu, Yao; Gao, Wei-Nan; Xue, Ya-Nan; Zhang, Li-Chao; Zhang, Juan-Juan; Lu, Sheng-Yao; Yan, Xiao-Yu; Yu, Hui-Mei; Su, Jing; Sun, Lian-Kun

2018-06-15

Increasing evidence suggests that mitochondrial respiratory chain complex I participates in carcinogenesis and cancer progression by providing energy and maintaining mitochondrial function. However, the role of complex I in ovarian cancer is largely unknown. In this study we showed that metformin, considered to be an inhibitor of complex I, simultaneously inhibited cell growth and induced mitochondrial-related apoptosis in human ovarian cancer cells. Metformin interrupted cellular energy metabolism mainly by causing damage to complex I that impacted mitochondrial function. Additionally, treatment with metformin increased the activation of sirtuin 3 (SIRT3), a mitochondrial deacetylase. We demonstrated that SIRT3 overexpression aggravated metformin-induced apoptosis, energy stress and mitochondrial dysfunction. Moreover, treatment with metformin or SIRT3 overexpression increased activation of AMP-activated protein kinase (AMPK), a major sensor of cellular energy status. AMPK compensated for energy loss by increasing glycolysis. The impact of this was assessed by reducing glucose levels in the media or by using inhibitors (2-deoxyglucose, Compound C) of glycolysis and AMPK. The combination of these factors with metformin intensified cytotoxicity through further downregulation of ATP. Our study outlines an important role for SIRT3 in the antitumor effect of mitochondrial complex I inhibitors in human ovarian cancer cells. This effect appears to be mediated by induction of energy stress and apoptosis. Strategies that target the mitochondria could be enhanced by modulating glycolysis to further aggravate energy stress that may increase the antitumor effect. Copyright © 2018 Elsevier Inc. All rights reserved.

Melatonin enhances neural stem cell differentiation and engraftment by increasing mitochondrial function.

PubMed

Mendivil-Perez, Miguel; Soto-Mercado, Viviana; Guerra-Librero, Ana; Fernandez-Gil, Beatriz I; Florido, Javier; Shen, Ying-Qiang; Tejada, Miguel A; Capilla-Gonzalez, Vivian; Rusanova, Iryna; Garcia-Verdugo, José M; Acuña-Castroviejo, Darío; López, Luis Carlos; Velez-Pardo, Carlos; Jimenez-Del-Rio, Marlene; Ferrer, José M; Escames, Germaine

2017-09-01

Neural stem cells (NSCs) are regarded as a promising therapeutic approach to protecting and restoring damaged neurons in neurodegenerative diseases (NDs) such as Parkinson's disease and Alzheimer's disease (PD and AD, respectively). However, new research suggests that NSC differentiation is required to make this strategy effective. Several studies have demonstrated that melatonin increases mature neuronal markers, which reflects NSC differentiation into neurons. Nevertheless, the possible involvement of mitochondria in the effects of melatonin during NSC differentiation has not yet been fully established. We therefore tested the impact of melatonin on NSC proliferation and differentiation in an attempt to determine whether these actions depend on modulating mitochondrial activity. We measured proliferation and differentiation markers, mitochondrial structural and functional parameters as well as oxidative stress indicators and also evaluated cell transplant engraftment. This enabled us to show that melatonin (25 μM) induces NSC differentiation into oligodendrocytes and neurons. These effects depend on increased mitochondrial mass/DNA/complexes, mitochondrial respiration, and membrane potential as well as ATP synthesis in NSCs. It is also interesting to note that melatonin prevented oxidative stress caused by high levels of mitochondrial activity. Finally, we found that melatonin enriches NSC engraftment in the ND mouse model following transplantation. We concluded that a combined therapy involving transplantation of NSCs pretreated with pharmacological doses of melatonin could efficiently restore neuronal cell populations in PD and AD mouse models depending on mitochondrial activity promotion. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

ΔN-Bcl-xL, a therapeutic target for neuroprotection

PubMed Central

Park, Han-A; Jonas, Elizabeth A.

2017-01-01

The B-cell lymphoma-extra large (Bcl-xL) is a mitochondrial anti-apoptotic protein that plays a role in neuroprotection. However, during excitotoxic stimulation, Bcl-xL undergoes caspase-dependent cleavage and produces a fragmented form, ΔN-Bcl-xL. Accumulation of ΔN-Bcl-xL is associated with mitochondrial dysfunction and neuronal death. Therefore, strategies to inhibit the activity or formation of ΔN-Bcl-xL protect the brain against excitotoxic injuries. Our team found that the pharmacological inhibitor ABT-737 exerts dose dependent effects in primary neurons. When primary hippocampal neurons were treated with 1 μM ABT-737, glutamate-mediated mitochondrial damage and neuronal death were exacerbated, whereas 10 nM ABT-737, a 100-fold lower concentration, protected mitochondrial function and enhanced neuronal viability against glutamate toxicity. In addition, we suggested acute vs. prolonged formation of ΔN-Bcl-xL may have different effects on mitochondrial or neuronal functions. Unlike acute production of ΔN-Bcl-xL by glutamate, overexpression of ΔN-Bcl-xL did not cause drastic changes in neuronal viability. We predicted that neurons undergo adaptation and may activate altered metabolism to compensate for ΔN-Bcl-xL-mediated mitochondrial dysfunction. Although the detailed mechanism of ABT-mediated neurotoxicity neuroprotection is still unclear, our study shows that the mitochondrial membrane protein ΔN-Bcl-xL is a central target for interventions. PMID:29239317

Inhibition of the Mitochondrial Fission Protein Drp1 Improves Survival in a Murine Cardiac Arrest Model

PubMed Central

Sharp, Willard W.; Beiser, David G.; Fang, Yong Hu; Han, Mei; Piao, Lin; Varughese, Justin; Archer, Stephen L.

2015-01-01

Objectives Survival following sudden cardiac arrest is poor despite advances in cardiopulmonary resuscitation (CPR) and the use of therapeutic hypothermia. Dynamin related protein 1 (Drp1), a regulator of mitochondrial fission, is an important determinant of reactive oxygen species generation, myocardial necrosis, and left ventricular function following ischemia/reperfusion injury, but its role in cardiac arrest is unknown. We hypothesized that Drp1 inhibition would improve survival, cardiac hemodynamics, and mitochondrial function in an in vivo model of cardiac arrest. Design Laboratory investigation. Setting University laboratory Interventions Anesthetized and ventilated adult female C57BL/6 wild-type mice underwent an 8-min KCl induced cardiac arrest followed by 90 seconds of CPR. Mice were then blindly randomized to a single intravenous injection of Mdivi-1 (0.24 mg/kg), a small molecule Drp1 inhibitor or vehicle (DMSO). Measurements and Main Results Following resuscitation from cardiac arrest, mitochondrial fission was evidenced by Drp1 translocation to the mitochondrial membrane and a decrease in mitochondrial size. Mitochondrial fission was associated with increased lactate and evidence of oxidative damage. Mdivi-1 administration during CPR inhibited Drp1 activation, preserved mitochondrial morphology, and decreased oxidative damage. Mdivi-1 also reduced the time to return of spontaneous circulation (ROSC) 116±4 vs. 143±7 sec (p<. 001) during CPR and enhanced myocardial performance post-ROSC. These improvements were associated with significant increases in survival (65% vs. 33%) and improved neurological scores up to 72 hours post cardiac arrest. Conclusions Post cardiac arrest inhibition of Drp1 improves time to ROSC and myocardial hemodynamics resulting in improved survival and neurological outcomes in a murine model of cardiac arrest. Pharmacological targeting of mitochondrial fission may be a promising therapy for cardiac arrest. PMID:25599491

Identity and function of a cardiac mitochondrial small conductance Ca2+-activated K+ channel splice variant

PubMed Central

Yang, MeiYing; Camara, Amadou K.S.; Aldakkak, Mohammed; Kwok, Wai-Meng; Stowe, David F.

2017-01-01

We provide evidence for location and function of a small conductance, Ca2+-activated K+ (SKCa) channel isoform 3 (SK3) in mitochondria (m) of guinea pig, rat and human ventricular myocytes. SKCa agonists protected isolated hearts and mitochondria against ischemia/reperfusion (IR) injury; SKCa antagonists worsened IR injury. Intravenous infusion of a SKCa channel agonist/antagonist, respectively, in intact rats was effective in reducing/enhancing regional infarct size induced by coronary artery occlusion. Localization of SK3 in mitochondria was evidenced by Western blot of inner mitochondrial membrane, immunocytochemical staining of cardiomyocytes, and immunogold labeling of isolated mitochondria. We identified a SK3 splice variant in guinea pig (SK3.1, aka SK3a) and human ventricular cells (SK3.2) by amplifying mRNA, and show mitochondrial expression in mouse atrial tumor cells (HL-1) by transfection with full length and truncated SK3.1 protein. We found that the Nterminus is not required for mitochondrial trafficking but the C-terminus beyond the Ca2+ calmodulin binding domain is required for Ca2+ sensing to induce mK+ influx and/or promote mitochondrial localization. In isolated guinea pig mitochondria and in SK3 overexpressed HL-1 cells, mK+ influx was driven by adding CaCl2. Moreover, there was a greater fall in membrane potential (ΔΨm), and enhanced cell death with simulated cell injury after silencing SK3.1 with siRNA. Although SKCa channel opening protects the heart and mitochondria against IR injury, the mechanism for favorable bioenergetics effects resulting from SKCa channel opening remains unclear. SKCa channels could play an essential role in restraining cardiac mitochondria from inducing oxidative stress-induced injury resulting from mCa2+ overload. PMID:28342809

Resveratrol counteracts bone loss via mitofilin-mediated osteogenic improvement of mesenchymal stem cells in senescence-accelerated mice

PubMed Central

Lv, Ya-Jie; Yang, Yi; Sui, Bing-Dong; Hu, Cheng-Hu; Zhao, Pan; Liao, Li; Chen, Ji; Zhang, Li-Qiang; Yang, Tong-Tao; Zhang, Shao-Feng; Jin, Yan

2018-01-01

Rational: Senescence of mesenchymal stem cells (MSCs) and the related functional decline of osteogenesis have emerged as the critical pathogenesis of osteoporosis in aging. Resveratrol (RESV), a small molecular compound that safely mimics the effects of dietary restriction, has been well documented to extend lifespan in lower organisms and improve health in aging rodents. However, whether RESV promotes function of senescent stem cells in alleviating age-related phenotypes remains largely unknown. Here, we intend to investigate whether RESV counteracts senescence-associated bone loss via osteogenic improvement of MSCs and the underlying mechanism. Methods: MSCs derived from bone marrow (BMMSCs) and the bone-specific, senescence-accelerated, osteoblastogenesis/osteogenesis-defective mice (the SAMP6 strain) were used as experimental models. In vivo application of RESV was performed at 100 mg/kg intraperitoneally once every other day for 2 months, and in vitro application of RESV was performed at 10 μM. Bone mass, bone formation rates and osteogenic differentiation of BMMSCs were primarily evaluated. Metabolic statuses of BMMSCs and the mitochondrial activity, transcription and morphology were also examined. Mitofilin expression was assessed at both mRNA and protein levels, and short hairpin RNA (shRNA)-based gene knockdown was applied for mechanistic experiments. Results: Chronic intermittent application of RESV enhances bone formation and counteracts accelerated bone loss, with RESV improving osteogenic differentiation of senescent BMMSCs. Furthermore, in rescuing osteogenic decline under BMMSC senescence, RESV restores cellular metabolism through mitochondrial functional recovery via facilitating mitochondrial autonomous gene transcription. Molecularly, in alleviating senescence-associated mitochondrial disorders of BMMSCs, particularly the mitochondrial morphological alterations, RESV upregulates Mitofilin, also known as inner membrane protein of mitochondria (Immt) or Mic60, which is the core component of the mitochondrial contact site and cristae organizing system (MICOS). Moreover, Mitofilin is revealed to be indispensable for mitochondrial homeostasis and osteogenesis of BMMSCs, and that insufficiency of Mitofilin leads to BMMSC senescence and bone loss. More importantly, Mitofilin mediates resveratrol-induced mitochondrial and osteogenic improvements of BMMSCs in senescence. Conclusion: Our findings uncover osteogenic functional improvements of senescent MSCs as critical impacts in anti-osteoporotic practice of RESV, and unravel Mitofilin as a novel mechanism mediating RESV promotion on mitochondrial function in stem cell senescence. PMID:29721087

Resveratrol counteracts bone loss via mitofilin-mediated osteogenic improvement of mesenchymal stem cells in senescence-accelerated mice.

PubMed

Lv, Ya-Jie; Yang, Yi; Sui, Bing-Dong; Hu, Cheng-Hu; Zhao, Pan; Liao, Li; Chen, Ji; Zhang, Li-Qiang; Yang, Tong-Tao; Zhang, Shao-Feng; Jin, Yan

2018-01-01

Rational: Senescence of mesenchymal stem cells (MSCs) and the related functional decline of osteogenesis have emerged as the critical pathogenesis of osteoporosis in aging. Resveratrol (RESV), a small molecular compound that safely mimics the effects of dietary restriction, has been well documented to extend lifespan in lower organisms and improve health in aging rodents. However, whether RESV promotes function of senescent stem cells in alleviating age-related phenotypes remains largely unknown. Here, we intend to investigate whether RESV counteracts senescence-associated bone loss via osteogenic improvement of MSCs and the underlying mechanism. Methods: MSCs derived from bone marrow (BMMSCs) and the bone-specific, senescence-accelerated, osteoblastogenesis/osteogenesis-defective mice (the SAMP6 strain) were used as experimental models. In vivo application of RESV was performed at 100 mg/kg intraperitoneally once every other day for 2 months, and in vitro application of RESV was performed at 10 μM. Bone mass, bone formation rates and osteogenic differentiation of BMMSCs were primarily evaluated. Metabolic statuses of BMMSCs and the mitochondrial activity, transcription and morphology were also examined. Mitofilin expression was assessed at both mRNA and protein levels, and short hairpin RNA (shRNA)-based gene knockdown was applied for mechanistic experiments. Results: Chronic intermittent application of RESV enhances bone formation and counteracts accelerated bone loss, with RESV improving osteogenic differentiation of senescent BMMSCs. Furthermore, in rescuing osteogenic decline under BMMSC senescence, RESV restores cellular metabolism through mitochondrial functional recovery via facilitating mitochondrial autonomous gene transcription. Molecularly, in alleviating senescence-associated mitochondrial disorders of BMMSCs, particularly the mitochondrial morphological alterations, RESV upregulates Mitofilin, also known as inner membrane protein of mitochondria (Immt) or Mic60, which is the core component of the mitochondrial contact site and cristae organizing system (MICOS). Moreover, Mitofilin is revealed to be indispensable for mitochondrial homeostasis and osteogenesis of BMMSCs, and that insufficiency of Mitofilin leads to BMMSC senescence and bone loss. More importantly, Mitofilin mediates resveratrol-induced mitochondrial and osteogenic improvements of BMMSCs in senescence. Conclusion: Our findings uncover osteogenic functional improvements of senescent MSCs as critical impacts in anti-osteoporotic practice of RESV, and unravel Mitofilin as a novel mechanism mediating RESV promotion on mitochondrial function in stem cell senescence.

Nicotinamide riboside attenuates alcohol induced liver injuries via activation of SirT1/PGC-1α/mitochondrial biosynthesis pathway.

PubMed

Wang, Sufan; Wan, Ting; Ye, Mingtong; Qiu, Yun; Pei, Lei; Jiang, Rui; Pang, Nengzhi; Huang, Yuanling; Liang, Baoxia; Ling, Wenhua; Lin, Xiaojun; Zhang, Zhenfeng; Yang, Lili

2018-07-01

Nicotinamide riboside (NR) is a nicotinamide adenine dinucleotide (NAD + ) precursor which is present in foods such as milk and beer. It was reported that NR can prevent obesity, increase longevity, and promote liver regeneration. However, whether NR can prevent ethanol-induced liver injuries is not known. This study aimed to explore the effect of NR on ethanol induced liver injuries and the underlying mechanisms. We fed C57BL/6 J mice with Lieber-DeCarli ethanol liquid diet with or without 400 mg/kg·bw NR for 16 days. Liver injuries and SirT1-PGC-1α-mitochondrial function were analyzed. In in vitro experiments, HepG2 cells (CYP2E1 over-expressing cells) were incubated with ethanol ± 0.5 mmol/L NR. Lipid accumulation and mitochondrial function were compared. SirT1 knockdown in HepG2 cells were further applied to confirm the role of SirT1 in the protection of NR on lipid accumulation. We found that ethanol significantly decreased the expression and activity of hepatic SirT1 and induced abnormal expression of enzymes of lipid metabolism in mice. Both in vivo and in vitro experiments showed that NR activated SirT1 through increasing NAD + levels, decreased oxidative stress, increased deacetylation of PGC-1α and mitochondrial function. In SirT1 knockdown HepG2 cells, NR lost its ability in enhancing mitochondrial function, and its protection against lipid accumulation induced by ethanol. NR can protect against ethanol induced liver injuries via replenishing NAD + , reducing oxidative stress, and activating SirT1-PGC-1α-mitochondrial biosynthesis. Our data indicate that SirT1 plays an important role in the protection of NR against lipid accumulation and mitochondrial dysfunctions induced by ethanol. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Unraveling the mechanism of neuroprotection of curcumin in arsenic induced cholinergic dysfunctions in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, Pranay; Yadav, Rajesh S.; Department of Crimnology and Forensic Science, Harisingh Gour University, Sagar 470 003

Earlier, we found that arsenic induced cholinergic deficits in rat brain could be protected by curcumin. In continuation to this, the present study is focused to unravel the molecular mechanisms associated with the protective efficacy of curcumin in arsenic induced cholinergic deficits. Exposure to arsenic (20 mg/kg body weight, p.o) for 28 days in rats resulted to decrease the expression of CHRM2 receptor gene associated with mitochondrial dysfunctions as evident by decrease in the mitochondrial membrane potential, activity of mitochondrial complexes and enhanced apoptosis both in the frontal cortex and hippocampus in comparison to controls. The ultrastructural images of arsenicmore » exposed rats, assessed by transmission electron microscope, exhibited loss of myelin sheath and distorted cristae in the mitochondria both in the frontal cortex and hippocampus as compared to controls. Simultaneous treatment with arsenic (20 mg/kg body weight, p.o) and curcumin (100 mg/kg body weight, p.o) for 28 days in rats was found to protect arsenic induced changes in the mitochondrial membrane potential and activity of mitochondrial complexes both in frontal cortex and hippocampus. Alterations in the expression of pro- and anti-apoptotic proteins and ultrastructural damage in the frontal cortex and hippocampus following arsenic exposure were also protected in rats simultaneously treated with arsenic and curcumin. The data of the present study reveal that curcumin could protect arsenic induced cholinergic deficits by modulating the expression of pro- and anti-apoptotic proteins in the brain. More interestingly, arsenic induced functional and ultrastructural changes in the brain mitochondria were also protected by curcumin. - Highlights: • Neuroprotective mechanism of curcumin in arsenic induced cholinergic deficits studied • Curcumin protected arsenic induced enhanced expression of stress markers in rat brain • Arsenic compromised mitochondrial electron transport chain protected by curcumin • Functional and structural changes in mitochondria by arsenic protected by curcumin.« less

Spinosad induces programmed cell death involves mitochondrial dysfunction and cytochrome C release in Spodoptera frugiperda Sf9 cells.

PubMed

Yang, Mingjun; Wang, Bo; Gao, Jufang; Zhang, Yang; Xu, Wenping; Tao, Liming

2017-02-01

Spinosad, a reduced-risk insecticide, acts on the nicotinic acetylcholine receptors and the gamma-aminobutyric acid receptor in the nervous system of target insects. However, its mechanism of action in non-neural insect cells is unclear. This study aimed to evaluate mitochondrial functional changes associated with spinosad in Spodoptera frugiperda (Sf9) insect cells. Our results indicate that in Sf9 cells, spinosad induces programmed cell death and mitochondrial dysfunction through enhanced reactive oxygen species production, mitochondrial permeability transition pore (mPTP) opening, and mitochondrial membrane potential collapse, eventually leading to cytochrome C release and apoptosis. The cytochrome C release induced by spinosad treatment was partly inhibited by the mPTP inhibitors cyclosporin A and bongkrekic acid. Subsequently, we found that spinosad downregulated Bcl-2 expression and upregulated p53 and Bax expressions, activated caspase-9 and caspase-3, and triggered PARP cleavage in Sf9 cells. These findings suggested that spinosad-induced programmed cell death was modulated by mitochondrial dysfunction and cytochrome C release. Copyright © 2016 Elsevier Ltd. All rights reserved.

Naringin Improves Neuronal Insulin Signaling, Brain Mitochondrial Function, and Cognitive Function in High-Fat Diet-Induced Obese Mice.

PubMed

Wang, Dongmei; Yan, Junqiang; Chen, Jing; Wu, Wenlan; Zhu, Xiaoying; Wang, Yong

2015-10-01

The epidemic and experimental studies have confirmed that the obesity induced by high-fat diet not only caused neuronal insulin resistance, but also induced brain mitochondrial dysfunction as well as learning impairment in mice. Naringin has been reported to posses biological functions which are beneficial to human cognitions, but its protective effects on HFD-induced cognitive deficits and underlying mechanisms have not been well characterized. In the present study Male C57BL/6 J mice were fed either a control or high-fat diet for 20 weeks and then randomized into four groups treated with their respective diets including control diet, control diet + naringin, high-fat diet (HFD), and high-fat diet + naringin (HFDN). The behavioral performance was assessed by using novel object recognition test and Morris water maze test. Hippocampal mitochondrial parameters were analyzed. Then the protein levels of insulin signaling pathway and the AMP-activated protein kinase (AMPK) in the hippocampus were detected by Western blot method. Our results showed that oral administration of naringin significantly improved the learning and memory abilities as evidenced by increasing recognition index by 52.5% in the novel object recognition test and inducing a 1.05-fold increase in the crossing-target number in the probe test, and ameliorated mitochondrial dysfunction in mice caused by HFD consumption. Moreover, naringin significantly enhanced insulin signaling pathway as indicated by a 34.5% increase in the expression levels of IRS-1, a 47.8% decrease in the p-IRS-1, a 1.43-fold increase in the p-Akt, and a 1.89-fold increase in the p-GSK-3β in the hippocampus of the HFDN mice versus HFD mice. Furthermore, the AMPK activity significantly increased in the naringin-treated (100 mg kg(-1) d(-1)) group. These findings suggest that an enhancement in insulin signaling and a decrease in mitochondrial dysfunction through the activation of AMPK may be one of the mechanisms that naringin improves cognitive functions in HFD-induced obese mice.

N-acetyl-cysteine increases cellular dysfunction in progressive chronic kidney damage after acute kidney injury by dampening endogenous antioxidant responses.

PubMed

Small, David M; Sanchez, Washington Y; Roy, Sandrine F; Morais, Christudas; Brooks, Heddwen L; Coombes, Jeff S; Johnson, David W; Gobe, Glenda C

2018-05-01

Oxidative stress and mitochondrial dysfunction exacerbate acute kidney injury (AKI), but their role in any associated progress to chronic kidney disease (CKD) remains unclear. Antioxidant therapies often benefit AKI, but their benefits in CKD are controversial since clinical and preclinical investigations often conflict. Here we examined the influence of the antioxidant N-acetyl-cysteine (NAC) on oxidative stress and mitochondrial function during AKI (20-min bilateral renal ischemia plus reperfusion/IR) and progression to chronic kidney pathologies in mice. NAC (5% in diet) was given to mice 7 days prior and up to 21 days post-IR (21d-IR). NAC treatment resulted in the following: prevented proximal tubular epithelial cell apoptosis at early IR (40-min postischemia), yet enhanced interstitial cell proliferation at 21d-IR; increased transforming growth factor-β1 expression independent of IR time; and significantly dampened nuclear factor-like 2-initiated cytoprotective signaling at early IR. In the long term, NAC enhanced cellular metabolic impairment demonstrated by increased peroxisome proliferator activator-γ serine-112 phosphorylation at 21d-IR. Intravital multiphoton microscopy revealed increased endogenous fluorescence of nicotinamide adenine dinucleotide (NADH) in cortical tubular epithelial cells during ischemia, and at 21d-IR that was not attenuated with NAC. Fluorescence lifetime imaging microscopy demonstrated persistent metabolic impairment by increased free/bound NADH in the cortex at 21d-IR that was enhanced by NAC. Increased mitochondrial dysfunction in remnant tubular cells was demonstrated at 21d-IR by tetramethylrhodamine methyl ester fluorimetry. In summary, NAC enhanced progression to CKD following AKI not only by dampening endogenous cellular antioxidant responses at time of injury but also by enhancing persistent kidney mitochondrial and metabolic dysfunction.

Low abundance of the matrix arm of complex I in mitochondria predicts longevity in mice

PubMed Central

Miwa, Satomi; Jow, Howsun; Baty, Karen; Johnson, Amy; Czapiewski, Rafal; Saretzki, Gabriele; Treumann, Achim; von Zglinicki, Thomas

2014-01-01

Mitochondrial function is an important determinant of the ageing process; however, the mitochondrial properties that enable longevity are not well understood. Here we show that optimal assembly of mitochondrial complex I predicts longevity in mice. Using an unbiased high-coverage high-confidence approach, we demonstrate that electron transport chain proteins, especially the matrix arm subunits of complex I, are decreased in young long-living mice, which is associated with improved complex I assembly, higher complex I-linked state 3 oxygen consumption rates and decreased superoxide production, whereas the opposite is seen in old mice. Disruption of complex I assembly reduces oxidative metabolism with concomitant increase in mitochondrial superoxide production. This is rescued by knockdown of the mitochondrial chaperone, prohibitin. Disrupted complex I assembly causes premature senescence in primary cells. We propose that lower abundance of free catalytic complex I components supports complex I assembly, efficacy of substrate utilization and minimal ROS production, enabling enhanced longevity. PMID:24815183

Respiromics - An integrative analysis linking mitochondrial bioenergetics to molecular signatures.

PubMed

Walheim, Ellen; Wiśniewski, Jacek R; Jastroch, Martin

2018-03-01

Energy metabolism is challenged upon nutrient stress, eventually leading to a variety of metabolic diseases that represent a major global health burden. Here, we combine quantitative mitochondrial respirometry (Seahorse technology) and proteomics (LC-MS/MS-based total protein approach) to understand how molecular changes translate to changes in mitochondrial energy transduction during diet-induced obesity (DIO) in the liver. The integrative analysis reveals that significantly increased palmitoyl-carnitine respiration is supported by an array of proteins enriching lipid metabolism pathways. Upstream of the respiratory chain, the increased capacity for ATP synthesis during DIO associates strongest to mitochondrial uptake of pyruvate, which is routed towards carboxylation. At the respiratory chain, robust increases of complex I are uncovered by cumulative analysis of single subunit concentrations. Specifically, nuclear-encoded accessory subunits, but not mitochondrial-encoded or core units, appear to be permissive for enhanced lipid oxidation. Our integrative analysis, that we dubbed "respiromics", represents an effective tool to link molecular changes to functional mechanisms in liver energy metabolism, and, more generally, can be applied for mitochondrial analysis in a variety of metabolic and mitochondrial disease models. Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.

Mitochondria-Targeted Antioxidant Prevents Cardiac Dysfunction Induced by Tafazzin Gene Knockdown in Cardiac Myocytes

PubMed Central

He, Quan; Harris, Nicole; Ren, Jun; Han, Xianlin

2014-01-01

Tafazzin, a mitochondrial acyltransferase, plays an important role in cardiolipin side chain remodeling. Previous studies have shown that dysfunction of tafazzin reduces cardiolipin content, impairs mitochondrial function, and causes dilated cardiomyopathy in Barth syndrome. Reactive oxygen species (ROS) have been implicated in the development of cardiomyopathy and are also the obligated byproducts of mitochondria. We hypothesized that tafazzin knockdown increases ROS production from mitochondria, and a mitochondria-targeted antioxidant prevents tafazzin knockdown induced mitochondrial and cardiac dysfunction. We employed cardiac myocytes transduced with an adenovirus containing tafazzin shRNA as a model to investigate the effects of the mitochondrial antioxidant, mito-Tempo. Knocking down tafazzin decreased steady state levels of cardiolipin and increased mitochondrial ROS. Treatment of cardiac myocytes with mito-Tempo normalized tafazzin knockdown enhanced mitochondrial ROS production and cellular ATP decline. Mito-Tempo also significantly abrogated tafazzin knockdown induced cardiac hypertrophy, contractile dysfunction, and cell death. We conclude that mitochondria-targeted antioxidant prevents cardiac dysfunction induced by tafazzin gene knockdown in cardiac myocytes and suggest mito-Tempo as a potential therapeutic for Barth syndrome and other dilated cardiomyopathies resulting from mitochondrial oxidative stress. PMID:25247053

Resveratrol improves mitochondrial function in the remnant kidney from 5/6 nephrectomized rats.

PubMed

Hui, Yan; Lu, Miaomiao; Han, Yarong; Zhou, Hongli; Liu, Wei; Li, Lijing; Jin, Ruixia

2017-05-01

Mitochondrial dysfunction is involved in the pathogenesis of chronic kidney disease (CKD). Resveratrol has been demonstrated to be beneficial for the recovery of kidney diseases. In this study, the 5/6 nephrectomized rat was used as a CKD model and the TGF-β1-exposed mouse mesangial cells were used as an in vitro model. Pathological examination showed that resveratrol treatment attenuated glomerular injury in the remnant kidney of 5/6 nephrectomized rat. Additionally, resveratrol improved mitochondrial function in vivo and in vitro, as evidenced by increasing mitochondrial membrane potential, increasing ATP, decreasing reactive oxygen species production and enhancing activities of complex I and III. Furthermore, the dysregulated expressions of electron transport chain proteins and fission/fusion proteins in the kidney of 5/6 nephrectomize rats and TGF-β1-exposed mesangial cells were restored by resveratrol. Finally, upregulated sirt1 and PGC-1α deacetylation were found after treatment with resveratrol in vivo and in vitro, which may contribute to the mitochondrial protective effects of resveratrol. The results demonstrate that resveratrol protects the mitochondria of kidney in 5/6 nephrectomized rats and TGF-β1 induced mesangial cells. The study provides new insights into the renoprotective mechanisms of resveratrol. Copyright © 2017 Elsevier GmbH. All rights reserved.

Effect of CCS on the Accumulation of FALS SOD1 Mutant-containing Aggregates and on Mitochondrial Translocation of SOD1 Mutants: Implication of a Free Radical Hypothesis

PubMed Central

Kim, Ha Kun; Chung, Youn Wook; Chock, P. Boon; Yim, Moon B.

2011-01-01

Missense mutations of SOD1 are linked to familial amyotrophic lateral sclerosis (FALS) through a yet-to-be identified toxic-gain-of-function. One of the proposed mechanisms involves enhanced aggregate formation. However, a recent study showed that dual transgenic mice overexpressing both G93A and CCS copper chaperone (G93A/CCS) exhibit no SOD1-positive aggregates yet show accelerated FALS symptoms with enhanced mitochondrial pathology compared to G93A mice. Using a dicistronic mRNA to simultaneously generate hSOD1 mutants, G93A, A4V and G85R, and hCCS in AAV293 cells, we revealed: (i) CCS is degraded primarily via a macroautophagy pathway. It forms a stable heterodimer with inactive G85R, and via its novel copper chaperone-independent molecular chaperone activity facilitates G85R degradation via a macroautophagy-mediated pathway. For active G93A and A4V, CCS catalyzes their maturation to form active and soluble homodimers. (ii) CCS reduces, under non-oxidative conditions, yet facilitates in the presence of H2O2, mitochondrial translocation of inactive SOD1 mutants. These results, together with previous reports showing FALS SOD1 mutants enhanced free radical-generating activity, provide a mechanistic explanation for the observations with G93A/CCS dual transgenic mice and suggest that free radical generation by FALS SOD1, enhanced by CCS, may, in part, be responsible for the FALS SOD1 mutant-linked aggregation, mitochondrial translocation, and degradation. PMID:21354101

In Vivo Mitochondrial Oxygen Tension Measured by a Delayed Fluorescence Lifetime Technique

PubMed Central

Mik, Egbert G.; Johannes, Tanja; Zuurbier, Coert J.; Heinen, Andre; Houben-Weerts, Judith H. P. M.; Balestra, Gianmarco M.; Stap, Jan; Beek, Johan F.; Ince, Can

2008-01-01

Mitochondrial oxygen tension (mitoPO2) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO2 in vivo exists. Here we report in vivo measurement of mitoPO2 and the recovery of mitoPO2 histograms in rat liver by a novel optical technique under normal and pathological circumstances. The technique is based on oxygen-dependent quenching of the delayed fluorescence lifetime of protoporphyrin IX. Application of 5-aminolevulinic acid enhanced mitochondrial protoporphyrin IX levels and induced oxygen-dependent delayed fluorescence in various tissues, without affecting mitochondrial respiration. Using fluorescence microscopy, we demonstrate in isolated hepatocytes that the signal is of mitochondrial origin. The delayed fluorescence lifetime was calibrated in isolated hepatocytes and isolated perfused livers. Ultimately, the technique was applied to measure mitoPO2 in rat liver in vivo. The results demonstrate mitoPO2 values of ∼30–40 mmHg. mitoPO2 was highly sensitive to small changes in inspired oxygen concentration around atmospheric oxygen level. Ischemia-reperfusion interventions showed altered mitoPO2 distribution, which flattened overall compared to baseline conditions. The reported technology is scalable from microscopic to macroscopic applications, and its reliance on an endogenous compound greatly enhances its potential field of applications. PMID:18641065

Antioxidant and Antitumor Activity of a Bioactive Polyphenolic Fraction Isolated from the Brewing Process

NASA Astrophysics Data System (ADS)

Tatullo, Marco; Simone, Grazia Maria; Tarullo, Franco; Irlandese, Gianfranco; Vito, Danila De; Marrelli, Massimo; Santacroce, Luigi; Cocco, Tiziana; Ballini, Andrea; Scacco, Salvatore

2016-10-01

There is increasing interest in identifying natural bioactive compounds that can improve mitochondrial functionality and regulate apoptosis. The brewery industry generates wastewater that could yield a natural extract containing bioactive phenolic compounds. Polyphenols act as antioxidants and have been documented to protect the human body from degenerative diseases such as cardiovascular diseases or cancer. The main aims of our research were to determine the phenolic profile of a crude extract obtained (at pilot scale) from a brewery waste stream and to evaluate the biochemical activity of this extract on the mitochondrial function of a cancer cell line (SH-SY5Y). This work is a basic translational pilot study. The total phenolic content was determined by the Folin-Ciocalteu assay, which revealed that 2.30% of the extract consisted of phenolic compounds. The polyphenols, identified and quantified by reverse-phase-high-performance liquid chromatography and mass spectrometry (RP-HPLC/MS), were mainly flavonoids. After cell culture, the tumoral cells treated with the polyphenolic extract showed enhanced mitochondrial oxidative function, which is likely related to a decrease in oxidative stress and an increase in mitochondrial biogenesis. This type of brewery waste stream, properly treated, may be a promising source of natural antioxidants to replace the synthetic antioxidants currently used in the food industry.

Antioxidant and Antitumor Activity of a Bioactive Polyphenolic Fraction Isolated from the Brewing Process

PubMed Central

Tatullo, Marco; Simone, Grazia Maria; Tarullo, Franco; Irlandese, Gianfranco; Vito, Danila De; Marrelli, Massimo; Santacroce, Luigi; Cocco, Tiziana; Ballini, Andrea; Scacco, Salvatore

2016-01-01

There is increasing interest in identifying natural bioactive compounds that can improve mitochondrial functionality and regulate apoptosis. The brewery industry generates wastewater that could yield a natural extract containing bioactive phenolic compounds. Polyphenols act as antioxidants and have been documented to protect the human body from degenerative diseases such as cardiovascular diseases or cancer. The main aims of our research were to determine the phenolic profile of a crude extract obtained (at pilot scale) from a brewery waste stream and to evaluate the biochemical activity of this extract on the mitochondrial function of a cancer cell line (SH-SY5Y). This work is a basic translational pilot study. The total phenolic content was determined by the Folin–Ciocalteu assay, which revealed that 2.30% of the extract consisted of phenolic compounds. The polyphenols, identified and quantified by reverse-phase-high-performance liquid chromatography and mass spectrometry (RP-HPLC/MS), were mainly flavonoids. After cell culture, the tumoral cells treated with the polyphenolic extract showed enhanced mitochondrial oxidative function, which is likely related to a decrease in oxidative stress and an increase in mitochondrial biogenesis. This type of brewery waste stream, properly treated, may be a promising source of natural antioxidants to replace the synthetic antioxidants currently used in the food industry. PMID:27786308

Gene-by-environment interactions that disrupt mitochondrial homeostasis cause neurodegeneration in C. elegans Parkinson's models.

PubMed

Kim, Hanna; Perentis, Rylee J; Caldwell, Guy A; Caldwell, Kim A

2018-05-10

Parkinson's disease (PD) is a complex multifactorial disorder where environmental factors interact with genetic susceptibility. Accumulating evidence suggests that mitochondria have a central role in the progression of neurodegeneration in sporadic and/or genetic forms of PD. We previously reported that exposure to a secondary metabolite from the soil bacterium, Streptomyces venezuelae, results in age- and dose-dependent dopaminergic (DA) neurodegeneration in Caenorhabditis elegans and human SH-SY5Y neurons. Initial characterization of this environmental factor indicated that neurodegeneration occurs through a combination of oxidative stress, mitochondrial complex I impairment, and proteostatic disruption. Here we present extended evidence to elucidate the interaction between this bacterial metabolite and mitochondrial dysfunction in the development of DA neurodegeneration. We demonstrate that it causes a time-dependent increase in mitochondrial fragmentation through concomitant changes in the gene expression of mitochondrial fission and fusion components. In particular, the outer mitochondrial membrane fission and fusion genes, drp-1 (a dynamin-related GTPase) and fzo-1 (a mitofusin homolog), are up- and down-regulated, respectively. Additionally, eat-3, an inner mitochondrial membrane fusion component, an OPA1 homolog, is also down regulated. These changes are associated with a metabolite-induced decline in mitochondrial membrane potential and enhanced DA neurodegeneration that is dependent on PINK-1 function. Genetic analysis also indicates an association between the cell death pathway and drp-1 following S. ven exposure. Metabolite-induced neurotoxicity can be suppressed by DA-neuron-specific RNAi knockdown of eat-3. AMPK activation by 5-amino-4-imidazole carboxamide riboside (AICAR) ameliorated metabolite- or PINK-1-induced neurotoxicity; however, it enhanced neurotoxicity under normal conditions. These studies underscore the critical role of mitochondrial dynamics in DA neurodegeneration. Moreover, given the largely undefined environmental components of PD etiology, these results highlight a response to an environmental factor that defines distinct mechanisms underlying a potential contributor to the progressive DA neurodegeneration observed in PD.

The mitochondrial uniporter controls fight or flight heart rate increases.

PubMed

Wu, Yuejin; Rasmussen, Tyler P; Koval, Olha M; Joiner, Mei-Ling A; Hall, Duane D; Chen, Biyi; Luczak, Elizabeth D; Wang, Qiongling; Rokita, Adam G; Wehrens, Xander H T; Song, Long-Sheng; Anderson, Mark E

2015-01-20

Heart rate increases are a fundamental adaptation to physiological stress, while inappropriate heart rate increases are resistant to current therapies. However, the metabolic mechanisms driving heart rate acceleration in cardiac pacemaker cells remain incompletely understood. The mitochondrial calcium uniporter (MCU) facilitates calcium entry into the mitochondrial matrix to stimulate metabolism. We developed mice with myocardial MCU inhibition by transgenic expression of a dominant-negative (DN) MCU. Here, we show that DN-MCU mice had normal resting heart rates but were incapable of physiological fight or flight heart rate acceleration. We found that MCU function was essential for rapidly increasing mitochondrial calcium in pacemaker cells and that MCU-enhanced oxidative phoshorylation was required to accelerate reloading of an intracellular calcium compartment before each heartbeat. Our findings show that MCU is necessary for complete physiological heart rate acceleration and suggest that MCU inhibition could reduce inappropriate heart rate increases without affecting resting heart rate.

Role and Treatment of Mitochondrial DNA-Related Mitochondrial Dysfunction in Sporadic Neurodegenerative Diseases

PubMed Central

Swerdlow, Russell H.

2012-01-01

Several sporadic neurodegenerative diseases display phenomena that directly or indirectly relate to mitochondrial function. Data suggesting altered mitochondrial function in these diseases could arise from mitochondrial DNA (mtDNA) are reviewed. Approaches for manipulating mitochondrial function and minimizing the downstream consequences of mitochondrial dysfunction are discussed. PMID:21902672

Nutritional support contributes to recuperation in a rat model of aplastic anemia by enhancing mitochondrial function.

PubMed

Yang, Guang; Zhao, Lifen; Liu, Bing; Shan, Yujia; Li, Yang; Zhou, Huimin; Jia, Li

2018-02-01

Acquired aplastic anemia (AA) is a hematopoietic stem cell disease that leads to hematopoietic disorder and peripheral blood pancytopenia. We investigated whether nutritional support is helpful to AA recovery. We established a rat model with AA. A nutrient mixture was administered to rats with AA through different dose gavage once per day for 55 d. Animals in this study were assigned to one of five groups: normal control (NC; group includes normal rats); AA (rats with AA); high dose (AA + nutritional mixture, 2266.95 mg/kg/d); medium dose (1511.3 mg/kg/d); and low dose (1057.91 mg/kg/d). The effects of nutrition administration on general status and mitochondrial function of rats with AA were evaluated. The nutrient mixture with which the rats were supplemented significantly improved weight, peripheral blood parameters, and histologic parameters of rats with AA in a dose-dependent manner. Furthermore, we observed that the number of mitochondria in the liver, spleen, kidney, and brain was increased after supplementation by transmission electron microscopy analysis. Nutrient administration also improved mitochondrial DNA content, adenosine triphosphate content, and membrane potential but inhibited oxidative stress, thus, repairing the mitochondrial dysfunction of the rats with AA. Taken together, nutrition supplements may contribute to the improvement of mitochondrial function and play an important role in the recuperation of rats with AA. Copyright © 2017 Elsevier Inc. All rights reserved.

Nicotinamide Forestalls Pathology and Cognitive Decline in Alzheimer Mice: Evidence for Improved Neuronal Bioenergetics and Autophagy Procession

PubMed Central

Liu, Dong; Pitta, Michael; Jiang, Haiyang; Lee, Jong-Hwan; Zhang, Guofeng; Chen, Xinzhi; Kawamoto, Elisa M.; Mattson, Mark P.

2012-01-01

Impaired brain energy metabolism and oxidative stress are implicated in cognitive decline and the pathological accumulations of amyloid β-peptide (Aβ) and hyperphosphorylated Tau (p-Tau) in Alzheimer's disease (AD). To determine whether improving brain energy metabolism will forestall disease progress in AD, the impact of the NAD+ precursor nicotinamide on brain cell mitochondrial function and macroautophagy, bioenergetics-related signaling and cognitive performance were studied in cultured neurons and in a mouse model of AD. Oxidative stress resulted in decreased mitochondrial mass, mitochondrial degeneration and autophagosome accumulation in neurons. Nicotinamide preserved mitochondrial integrity and autophagy function, and reduced neuronal vulnerability to oxidative/metabolic insults and Aβ toxicity. NAD+ biosynthesis, autophagy and PI3K signaling were required for the neuroprotective action of nicotinamide. Treatment of 3xTgAD mice with nicotinamide for 8 months resulted in improved cognitive performance, and reduced Aβ and p-Tau pathologies in hippocampus and cerebral cortex. Nicotinamide treatment preserved mitochondrial integrity, and improved autophagy-lysosome procession by enhancing lysosome/autolysosome acidification to reduce autophagosome accumulation. Treatment of 3xTgAD mice with nicotinamide resulted in elevated levels of activated neuroplasticity-related kinases (Akt and ERKs) and the transcription factor cyclic AMP response element-binding protein in the hippocampus and cerebral cortex. Thus, nicotinamide suppresses AD pathology and cognitive decline in a mouse model of AD by a mechanism involving improved brain bioenergetics with preserved functionality of mitochondria and the autophagy system. PMID:23273573

Msh1p counteracts oxidative lesion-induced instability of mtDNA and stimulates mitochondrial recombination in Saccharomyces cerevisiae.

PubMed

Kaniak, Aneta; Dzierzbicki, Piotr; Rogowska, Agata T; Malc, Ewa; Fikus, Marta; Ciesla, Zygmunt

2009-03-01

The proximity of the mitochondrial genome to the respiratory chain, a major source of ROS (radical oxygen species), makes mtDNA more vulnerable to oxidative damage than nuclear DNA. Mitochondrial BER (base excision repair) is generally considered to be the main pathway involved in the prevention of oxidative lesion-induced mutations in mtDNA. However, we previously demonstrated that the increased frequency of mitochondrial Oli(r) mutants in an ogg1Delta strain, lacking the activity of a crucial mtBER glycosylase, is reduced in the presence of plasmids encoding Msh1p, the mitochondrial homologue of the bacterial mismatch protein MutS. This finding suggested that Msh1p might be involved in the prevention of mitochondrial mutagenesis induced by oxidative stress. Here we show that a double mutant carrying the msh1-R813W allele, encoding a variant of the protein defective in the ATP hydrolysis activity, combined with deletion of SOD2, encoding the mitochondrial superoxide dismutase, displays a synergistic effect on the frequency of Oli(r) mutants, indicating that Msh1p prevents generation of oxidative lesion-induced mitochondrial mutations. We also show that double mutants carrying the msh1-R813W allele, combined with deletion of either OGG1 or APN1, the latter resulting in deficiency of the Apn1 endonuclease, exhibit a synergistic effect on the frequency of respiration-defective mutants having gross rearrangements of the mitochondrial genome. This suggests that Msh1p, Ogg1p and Apn1p play overlapping functions in maintaining the stability of mtDNA. In addition, we demonstrate, using a novel ARG8(m) recombination assay, that a surplus of Msh1p results in enhanced mitochondrial recombination. Interestingly, the mutant forms of the protein, msh1p-R813W and msh1p-G776D, fail to stimulate recombination. We postulate that the Msh1p-enhanced homologous recombination may play an important role in the prevention of oxidative lesion-induced rearrangements of the mitochondrial genome.

Intramitochondrial Ascorbic Acid Enhances the Formation of Mitochondrial Superoxide Induced by Peroxynitrite via a Ca2+-Independent Mechanism

PubMed Central

Guidarelli, Andrea; Cerioni, Liana; Fiorani, Mara; Cantoni, Orazio

2017-01-01

Exposure of U937 cells to peroxynitrite promotes mitochondrial superoxide formation via a mechanism dependent on both inhibition of complex III and increased mitochondrial Ca2+ accumulation. Otherwise inactive concentrations of the oxidant produced the same maximal effects in the presence of either complex III inhibitors or agents mobilizing Ca2+ from the ryanodine receptor and enforcing its mitochondrial accumulation. l-Ascorbic acid (AA) produced similar enhancing effects in terms of superoxide formation, DNA strand scission and cytotoxicity. However, AA failed to enhance the intra-mitochondrial concentration of Ca2+ and the effects observed in cells supplemented with peroxinitrite, while insensitive to manipulations preventing the mobilization of Ca2+, or the mitochondrial accumulation of the cation, were also detected in human monocytes and macrophages, which do not express the ryanodine receptor. In all these cell types, mitochondrial permeability transition-dependent toxicity was detected in cells exposed to AA/peroxynitrite and, based on the above criteria, these responses also appeared Ca2+-independent. The enhancing effects of AA are therefore similar to those mediated by bona fide complex III inhibitors, although the vitamin failed to directly inhibit complex III, and in fact enhanced its sensitivity to the inhibitory effects of peroxynitrite. PMID:28767071

Ameliorating Endothelial Mitochondrial Dysfunction Restores Coronary Function via Transient Receptor Potential Vanilloid 1-Mediated Protein Kinase A/Uncoupling Protein 2 Pathway.

PubMed

Xiong, Shiqiang; Wang, Peijian; Ma, Liqun; Gao, Peng; Gong, Liuping; Li, Li; Li, Qiang; Sun, Fang; Zhou, Xunmei; He, Hongbo; Chen, Jing; Yan, Zhencheng; Liu, Daoyan; Zhu, Zhiming

2016-02-01

Coronary heart disease arising from atherosclerosis is a leading cause of cardiogenic death worldwide. Mitochondria are the principal source of reactive oxygen species (ROS), and defective oxidative phosphorylation by the mitochondrial respiratory chain contributes to ROS generation. Uncoupling protein 2 (UCP2), an adaptive antioxidant defense factor, protects against mitochondrial ROS-induced endothelial dysfunction in atherosclerosis. The activation of transient receptor potential vanilloid 1 (TRPV1) attenuates vascular dysfunction. Therefore, whether TRPV1 activation antagonizes coronary lesions by alleviating endothelial mitochondrial dysfunction and enhancing the activity of the protein kinase A/UCP2 pathway warrants examination. ApoE(-/-), ApoE(-/-)/TRPV1(-/-), and ApoE(-/-)/UCP2(-/-) mice were fed standard chow, a high-fat diet (HFD), or the HFD plus 0.01% capsaicin. HFD intake profoundly impaired coronary vasodilatation and myocardial perfusion and shortened the survival duration of ApoE(-/-) mice. TRPV1 or UCP2 deficiency exacerbated HFD-induced coronary dysfunction and was associated with increased ROS generation and reduced nitric oxide production in the endothelium. The activation of TRPV1 by capsaicin upregulated UCP2 expression via protein kinase A phosphorylation, thereby alleviating endothelial mitochondrial dysfunction and inhibiting mitochondrial ROS generation. In vivo, dietary capsaicin supplementation enhanced coronary relaxation and prolonged the survival duration of HFD-fed ApoE(-/-) mice. These effects were not observed in ApoE(-/-) mice lacking the TRPV1 or UCP2 gene. The upregulation of protein kinase A /UCP2 via TRPV1 activation ameliorates coronary dysfunction and prolongs the lifespan of atherosclerotic mice by ameliorating endothelial mitochondrial dysfunction. Dietary capsaicin supplementation may represent a promising intervention for the primary prevention of coronary heart disease. © 2015 American Heart Association, Inc.

Blocking mitochondrial cyclophilin D ameliorates TSH-impaired defensive barrier of artery.

PubMed

Liu, Xiaojing; Du, Heng; Chai, Qiang; Jia, Qing; Liu, Lu; Zhao, Meng; Li, Jun; Tang, Hui; Chen, Wenbin; Zhao, Lifang; Fang, Li; Gao, Ling; Zhao, Jiajun

2018-05-01

Endothelial cells (ECs) constitute the defensive barrier of vasculature, which maintains the vascular homeostasis. Mitochondrial oxidative stress (mitoOS) in ECs significantly affects the initiation and progression of vascular diseases. The higher serum thyroid stimulating hormone (TSH) level is being recognized as a nonconventional risk factor responsible for the increased risk of cardiovascular diseases in subclinical hypothyroidism (SCH). However, effects and underlying mechanisms of elevated TSH on ECs are still ambiguous. We sought to investigate whether cyclophilin D (CypD), emerging as a crucial mediator in mitoOS, regulates effects of TSH on ECs. SCH patients with TSH > = 10mIU/L showed a positive correlation between serum TSH and endothelin-1 levels. When TSH levels declined to normal in these subjects after levothyroxine therapy, serum endothelin-1 levels were significantly reduced. Supplemented with exogenous thyroxine to keep normal thyroid hormones, thyroid-specific TSH receptor (TSHR)-knockout mice with injection of exogenous TSH exhibited elevated serum TSH levels, significant endothelial oxidative injuries and disturbed endothelium-dependent vasodilation. However, Tshr -/- mice resisted to TSH-impaired vasotonia. We further confirmed that elevated TSH triggered excessive mitochondrial permeability transition pore (mPTP) opening and mitochondrial oxidative damages in mouse aorta, as well as in cultured ECs. Genetic or pharmacological inhibition of CypD (the key regulator for mPTP opening) attenuated TSH-induced mitochondrial oxidative damages and further rescued endothelial functions. Finally, we confirmed that elevated TSH could activate CypD by enhancing CypD acetylation via inhibiting adenosine monophosphate-activated protein kinase/sirtuin-3 signaling pathway in ECs. These findings reveal that elevated TSH triggers mitochondrial perturbations in ECs and provide insights that blocking mitochondrial CypD enhances the defensive ability of ECs under TSH exposure. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Deficient mitochondrial biogenesis in IL-2 activated NK cells correlates with impaired PGC1-α upregulation in elderly humans.

PubMed

Miranda, Dante; Jara, Claudia; Mejias, Sophia; Ahumada, Viviana; Cortez-San Martin, Marcelo; Ibañez, Jorge; Hirsch, Sandra; Montoya, Margarita

2018-05-18

Immunosenescence has been described as age-associated changes in the immune function which are thought to be responsible for the increased morbidity with age. Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in immune defense against tumor and microbial diseases. Interestingly, aging-related NK cell dysfunction is associated with features of aging such as tumor incidence, reduced vaccination efficacy, and short survival due to infection. It is known that NK cell effector functions are critically dependent on cytokines and metabolic activity. Our aim was to determine whether there is a difference in purified human NK cell function in response to high concentration of IL-2 between young and elder donors. Here, we report that the stimulation of human NK cells with IL-2 (2000 U/mL) enhance NK cell cytotoxic activity from both young and elderly donors. However, while NK cells from young people responded to IL-2 signaling by increasing mitochondrial mass and mitochondrial membrane potential, no increase in these mitochondrial functional parameters was seen in purified NK cells from elderly subjects. Moreover, as purified NK cells from the young exhibited an almost three-fold increase in PGC-1α expression after IL-2 (2000 U/mL) stimulation, PGC-1α expression was inhibited in purified NK cells from elders. Furthermore, this response upon PGC-1α expression after IL-2 stimulation promoted an increase in ROS production in NK cells from elderly humans, while no increase in ROS production was observed in NK cells of young donors. Our data show that IL-2 stimulates NK cell effector function through a signaling pathway which involves a PGC-1α-dependent mitochondrial function in young NK cells, however it seems that NK cells from older donors exhibit an altered IL-2 signaling which affects mitochondrial function associated with an increased production of ROS which could represent a feature of NK cell senescence. Copyright © 2018 Elsevier Inc. All rights reserved.

Mitochondrial ATF2 translocation contributes to apoptosis induction and BRAF inhibitor resistance in melanoma through the interaction of Bim with VDAC1.

PubMed

Gao, Zongwei; Shang, Qingjuan; Liu, Zhaoyun; Deng, Chun; Guo, Chunbao

2015-11-03

The mitochondrial accumulation of ATF2 is involved in tumor suppressor activities via cytochrome c release in melanoma cells. However, the signaling pathways that connect mitochondrial ATF2 accumulation and cytochrome c release are not well documented. Several melanoma cell lines, B16F10, K1735M2, A375 and A375-R1, were treated with paclitaxel and vemurafenib to test the function of mitochondrial ATF2 and its connection to Bim and voltage-dependent anion channel 1 (VDAC1). Immunoprecipitation analysis was performed to investigate the functional interaction between the involved proteins. VDAC1 oligomerization was evaluated using an EGS-based crosslinking assay. The expression and migration of ATF2 to the mitochondria accounted for paclitaxel stimuli and acquired resistance to BRAF inhibitors. Mitochondrial ATF2 facilitated Bim stabilization through the inhibition of its degradation by the proteasome, thereby promoting cytochrome c release and inducing apoptosis in B16F10 and A375 cells. Studies using B16F10 and A375 cells genetically modified for ATF2 indicated that mitochondrial ATF2 was able to dissociate Bim from the Mcl-1/Bim complex to trigger VDAC1 oligomerization. Immunoprecipitation analysis revealed that Bim interacts with VDAC1, and this interaction was remarkably enhanced during apoptosis. These results reveal that mitochondrial ATF2 is associated with the induction of apoptosis and BRAF inhibitor resistance through Bim activation, which might suggest potential novel therapies for the targeted induction of apoptosis in melanoma therapy.

Mitochondrial ATF2 translocation contributes to apoptosis induction and BRAF inhibitor resistance in melanoma through the interaction of Bim with VDAC1

PubMed Central

Deng, Chun; Guo, Chunbao

2015-01-01

Background The mitochondrial accumulation of ATF2 is involved in tumor suppressor activities via cytochrome c release in melanoma cells. However, the signaling pathways that connect mitochondrial ATF2 accumulation and cytochrome c release are not well documented. Methods Several melanoma cell lines, B16F10, K1735M2, A375 and A375-R1, were treated with paclitaxel and vemurafenib to test the function of mitochondrial ATF2 and its connection to Bim and voltage-dependent anion channel 1 (VDAC1). Immunoprecipitation analysis was performed to investigate the functional interaction between the involved proteins. VDAC1 oligomerization was evaluated using an EGS-based crosslinking assay. Results The expression and migration of ATF2 to the mitochondria accounted for paclitaxel stimuli and acquired resistance to BRAF inhibitors. Mitochondrial ATF2 facilitated Bim stabilization through the inhibition of its degradation by the proteasome, thereby promoting cytochrome c release and inducing apoptosis in B16F10 and A375 cells. Studies using B16F10 and A375 cells genetically modified for ATF2 indicated that mitochondrial ATF2 was able to dissociate Bim from the Mcl-1/Bim complex to trigger VDAC1 oligomerization. Immunoprecipitation analysis revealed that Bim interacts with VDAC1, and this interaction was remarkably enhanced during apoptosis. Conclusion These results reveal that mitochondrial ATF2 is associated with the induction of apoptosis and BRAF inhibitor resistance through Bim activation, which might suggest potential novel therapies for the targeted induction of apoptosis in melanoma therapy. PMID:26462148

PDGF-AA-induced filamentous mitochondria benefit dermal papilla cells in cellular migration.

PubMed

Mifude, C; Kaseda, K

2015-06-01

Human dermal papilla cells (HDPCs) play essential roles in hair follicular morphogenesis and postnatal hair growth cycles. Previous reports demonstrated that platelet-derived growth factor-AA (PDGF-AA) enhanced the formation of dermal condensates in hair follicular development. Additionally, PDGF-AA induces/maintains the anagen phase of the hair cycle. It is likely that mitochondrial morphology and functions are tightly coupled with maintenance of these energy-demanding activities. However, little is known about the mitochondrial regulation in HDPCs. Thus, we investigated the PDGF-involved mitochondrial regulation in HDPCs. The mitochondrial morphologies of HDPCs were examined in the presence or absence of PDGF-AA under a fluorescent microscope. ATP production and cellular motility were investigated. The relationship between mitochondrial morphology and the cellular functions was discussed. We observed that primary HDPCs contained mitochondria with filamentous and/or rounded morphologies. Both types of mitochondria showed similar membrane potentials. Interestingly, in the presence of PDGF-AA, but not PDGF-BB, the balance between the two morphologies shifted towards the filamentous form. Concomitantly, both mitochondrial enzymatic activity and total cellular ATP level were augmented by PDGF-AA. These two parameters were closely correlated, suggesting the mitochondrial involvement in the PDGF-augmented ATP production. Moreover, PDGF-AA accelerated the migration of HDPCs in a gap-filling assay, but did not change the rate of cellular proliferation. Notably, filamentous mitochondria dominated migrating HDPCs. PDGF-AA benefits HDPCs in the process of migration, by increasing the number of filamentous mitochondria. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

The methyl donor S-adenosylmethionine prevents liver hypoxia and dysregulation of mitochondrial bioenergetic function in a rat model of alcohol-induced fatty liver disease.

PubMed

King, Adrienne L; Mantena, Sudheer K; Andringa, Kelly K; Millender-Swain, Telisha; Dunham-Snary, Kimberly J; Oliva, Claudia R; Griguer, Corinne E; Bailey, Shannon M

2016-10-01

Mitochondrial dysfunction and bioenergetic stress play an important role in the etiology of alcoholic liver disease. Previous studies from our laboratory show that the primary methyl donor S-Adenosylmethionine (SAM) minimizes alcohol-induced disruptions in several mitochondrial functions in the liver. Herein, we expand on these earlier observations to determine whether the beneficial actions of SAM against alcohol toxicity extend to changes in the responsiveness of mitochondrial respiration to inhibition by nitric oxide (NO), induction of the mitochondrial permeability transition (MPT) pore, and the hypoxic state of the liver. For this, male Sprague-Dawley rats were pair-fed control and alcohol-containing liquid diets with and without SAM for 5 weeks and liver hypoxia, mitochondrial respiration, MPT pore induction, and NO-dependent control of respiration were examined. Chronic alcohol feeding significantly enhanced liver hypoxia, whereas SAM supplementation attenuated hypoxia in livers of alcohol-fed rats. SAM supplementation prevented alcohol-mediated decreases in mitochondrial state 3 respiration and cytochrome c oxidase activity. Mitochondria isolated from livers of alcohol-fed rats were more sensitive to calcium-mediated MPT pore induction (i.e., mitochondrial swelling) than mitochondria from pair-fed controls, whereas SAM treatment normalized sensitivity for calcium-induced swelling in mitochondria from alcohol-fed rats. Liver mitochondria from alcohol-fed rats showed increased sensitivity to NO-dependent inhibition of respiration compared with pair-fed controls. In contrast, mitochondria isolated from the livers of SAM treated alcohol-fed rats showed no change in the sensitivity to NO-mediated inhibition of respiration. Collectively, these findings indicate that the hepato-protective effects of SAM against alcohol toxicity are mediated, in part, through a mitochondrial mechanism involving preservation of key mitochondrial bioenergetic parameters and the attenuation of hypoxic stress. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Treatment with geraniol ameliorates methionine-choline-deficient diet-induced non-alcoholic steatohepatitis in rats.

PubMed

Chen, Jun; Fan, Xiaoxia; Zhou, Lin; Gao, Xiaogang

2016-07-01

Non-alcoholic steatohepatitis (NASH) is one of the most common causes of chronic liver disease and is considered to be a causative factor of cryptogenic cirrhosis and hepatocellular carcinoma. The aim of this work was to investigate whether treatment with geraniol (a monoterpene) attenuated NASH induced by methionine-choline-deficient (MCD) diet in rats. Rats were fed with MCD diet to induce NASH and treated with geraniol (200 mg/kg/day) for 10 weeks. Treatment with geraniol reduced histological scores, fibrosis, and apoptosis in livers, lowered activities of alanine aminotransferase and aspartate aminotransferase in serum, and attenuated hepatic fat accumulation in rats fed with MCD diet. Treatment with geraniol preserved hepatic mitochondrial function, evidenced by reduced mitochondrial reactive oxygen species formation, enhanced adenosine triphosphate formation and membrane integrity, restored mitochondrial electron transport chain enzyme activity, and increased mitochondrial DNA content in rats fed with MCD diet. Treatment with geraniol reduced uncoupling protein 2 protein expression, and enhanced protein expression of prohibitin, mRNA expression of peroxisome proliferator-activated receptor α, and activity of mitochondrial carnitine palmitoyl transferase-I in livers of rats fed with MCD diet. Treatment with geraniol abated oxidative stress, evidenced by reduced malondialdehyde and 3-nitrotyrosine formation, enhanced activity of glutathione S-epoxide transferase, and down-regulated expression of inducible nitric oxide synthase and cytochrome P450 2E1 in livers of rats fed with MCD diet. Treatment with geraniol reduced myeloperoxidase activity and protein expression of tumor necrosis factor alpha and IL-6 in livers of rats fed with MCD diet. Treatment with geraniol attenuated MCD-induced NASH in rats. © 2015 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Carbon monoxide improves neuronal differentiation and yield by increasing the functioning and number of mitochondria.

PubMed

Almeida, Ana S; Sonnewald, Ursula; Alves, Paula M; Vieira, Helena L A

2016-08-01

The process of cell differentiation goes hand-in-hand with metabolic adaptations, which are needed to provide energy and new metabolites. Carbon monoxide (CO) is an endogenous cytoprotective molecule able to inhibit cell death and improve mitochondrial metabolism. Neuronal differentiation processes were studied using the NT2 cell line, which is derived from human testicular embryonic teratocarcinoma and differentiates into post-mitotic neurons upon retinoic acid treatment. CO-releasing molecule A1 (CORM-A1) was used do deliver CO into cell culture. CO treatment improved NT2 neuronal differentiation and yield, since there were more neurons and the total cell number increased following the differentiation process. CO supplementation enhanced the mitochondrial population in post-mitotic neurons derived from NT2 cells, as indicated by an increase in mitochondrial DNA. CO treatment during neuronal differentiation increased the extent of the classical metabolic change that occurs during neuronal differentiation, from glycolytic to more oxidative metabolism, by decreasing the ratio of lactate production and glucose consumption. The expression of pyruvate and lactate dehydrogenases was higher, indicating an augmented oxidative metabolism. Moreover, these findings were corroborated by an increased percentage of (13) C incorporation from [U-(13) C]glucose into the tricarboxylic acid cycle metabolites malate and citrate, and also glutamate and aspartate in CO-treated cells. Finally, under low levels of oxygen (5%), which enhances glycolytic metabolism, some of the enhancing effects of CO on mitochondria were not observed. In conclusion, our data show that CO improves neuronal and mitochondrial yield by stimulation of tricarboxylic acid cycle activity, and thus oxidative metabolism of NT2 cells during the process of neuronal differentiation. The process of cell differentiation is coupled with metabolic adaptations. Carbon monoxide (CO) is an endogenous cytoprotective gasotransmitter able to prevent cell death and improve mitochondrial metabolism. Herein CO supplementation improved neuronal differentiation yield, by enhancing mitochondrial population and promoting the classical metabolic change that occurs during neuronal differentiation, from glycolytic to oxidative metabolism. © 2016 International Society for Neurochemistry.

Oncostatin M (OSM) protects against cardiac ischaemia/reperfusion injury in diabetic mice by regulating apoptosis, mitochondrial biogenesis and insulin sensitivity.

PubMed

Sun, Dongdong; Li, Shuang; Wu, Hao; Zhang, Mingming; Zhang, Xiaotian; Wei, Liping; Qin, Xing; Gao, Erhe

2015-06-01

Oncostatin M (OSM) exhibits many unique biological activities by activating Oβ receptor. However, its role in myocardial I/R injury in diabetic mice remains unknown. The involvement of OSM was assessed in diabetic mice which underwent myocardial I/R injury by OSM treatment or genetic deficiency of OSM receptor Oβ. Its mechanism on cardiomyocyte apoptosis, mitochondrial biogenesis and insulin sensitivity were further studied. OSM alleviated cardiac I/R injury by inhibiting cardiomyocyte apoptosis through inhibition of inositol pyrophosphate 7 (IP7) production, thus activating PI3K/Akt/BAD pathway, decreasing Bax expression while up-regulating Bcl-2 expression and decreasing the ratio of Bax to Bcl-2 in db/db mice. OSM enhanced mitochondrial biogenesis and mitochondrial function in db/db mice subjected to cardiac I/R injury. On the contrary, OSM receptor Oβ knockout exacerbated cardiac I/R injury, increased IP7 production, enhanced cardiomyocyte apoptosis, impaired mitochondrial biogenesis, glucose homoeostasis and insulin sensitivity in cardiac I/R injured diabetic mice. Inhibition of IP7 production by TNP (IP6K inhibitor) exerted similar effects of OSM. The mechanism of OSM on cardiac I/R injury in diabetic mice is partly associated with IP7/Akt and adenine mononucleotide protein kinase/PGC-1α pathway. OSM protects against cardiac I/R Injury by regulating apoptosis, insulin sensitivity and mitochondrial biogenesis in diabetic mice through inhibition of IP7 production. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Niemann-Pick Type C2 Protein Regulates Free Cholesterol Accumulation and Influences Hepatic Stellate Cell Proliferation and Mitochondrial Respiration Function.

PubMed

Wang, Yuan-Hsi; Twu, Yuh-Ching; Wang, Chung-Kwe; Lin, Fu-Zhen; Lee, Chun-Ya; Liao, Yi-Jen

2018-06-05

Liver fibrosis is the first step toward the progression to cirrhosis, portal hypertension, and hepatocellular carcinoma. A high-cholesterol diet is associated with liver fibrosis via the accumulation of free cholesterol in hepatic stellate cells (HSCs). Niemann-Pick type C2 (NPC2) plays an important role in the regulation of intracellular free cholesterol homeostasis via direct binding with free cholesterol. Previously, we reported that NPC2 was downregulated in liver cirrhosis tissues. Loss of NPC2 enhanced the accumulation of free cholesterol in HSCs and made them more susceptible to transforming growth factor (TGF)-β1. In this study, we showed that knockdown of NPC2 resulted in marked increases in platelet-derived growth factor BB (PDGF-BB)-induced HSC proliferation through enhanced extracellular signal-regulated kinases (ERK), p38, c-Jun N-terminal kinases (JNK), and protein kinase B (AKT) phosphorylation. In contrast, NPC2 overexpression decreased PDGF-BB-induced cell proliferation by inhibiting p38, JNK, and AKT phosphorylation. Although NPC2 expression did not affect caspase-related apoptosis, the autophagy marker light chain 3β (LC3B) was decreased in NPC2 knockdown, and free cholesterol accumulated in the HSCs. The mitochondrial respiration functions (such as oxygen consumption rate, ATP production, and maximal respiratory capacity) were decreased in NPC2 knockdown, and free cholesterol accumulated in the HSCs, while NPC2-overexpressed cells remained normal. In addition, NPC2 expression did not affect the susceptibility of HSCs to lipopolysaccharides (LPS), and U18666A treatment induced free cholesterol accumulation, which enhanced LPS-induced Toll-like receptor 4 (TLR4), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 phosphorylation, interleukin (IL)-1 and IL-6 expression. Our study demonstrated that NPC2-mediated free cholesterol homeostasis controls HSC proliferation and mitochondrial function.

Mitochondrial Ceramide-Rich Macrodomains Functionalize Bax upon Irradiation

PubMed Central

Lee, Hyunmi; Rotolo, Jimmy A.; Mesicek, Judith; Penate-Medina, Tuula; Rimner, Andreas; Liao, Wen-Chieh; Yin, Xianglei; Ragupathi, Govind; Ehleiter, Desiree; Gulbins, Erich; Zhai, Dayong; Reed, John C.; Haimovitz-Friedman, Adriana; Fuks, Zvi; Kolesnick, Richard

2011-01-01

Background Evidence indicates that Bax functions as a “lipidic” pore to regulate mitochondrial outer membrane permeabilization (MOMP), the apoptosis commitment step, through unknown membrane elements. Here we show mitochondrial ceramide elevation facilitates MOMP-mediated cytochrome c release in HeLa cells by generating a previously-unrecognized mitochondrial ceramide-rich macrodomain (MCRM), which we visualize and isolate, into which Bax integrates. Methodology/Principal Findings MCRMs, virtually non-existent in resting cells, form upon irradiation coupled to ceramide synthase-mediated ceramide elevation, optimizing Bax insertion/oligomerization and MOMP. MCRMs are detected by confocal microscopy in intact HeLa cells and isolated biophysically as a light membrane fraction from HeLa cell lysates. Inhibiting ceramide generation using a well-defined natural ceramide synthase inhibitor, Fumonisin B1, prevented radiation-induced Bax insertion, oligomerization and MOMP. MCRM deconstruction using purified mouse hepatic mitochondria revealed ceramide alone is non-apoptogenic. Rather Bax integrates into MCRMs, oligomerizing therein, conferring 1–2 log enhanced cytochrome c release. Consistent with this mechanism, MCRM Bax isolates as high molecular weight “pore-forming” oligomers, while non-MCRM membrane contains exclusively MOMP-incompatible monomeric Bax. Conclusions/Significance Our recent studies in the C. elegans germline indicate that mitochondrial ceramide generation is obligate for radiation-induced apoptosis, although a mechanism for ceramide action was not delineated. Here we demonstrate that ceramide, generated in the mitochondrial outer membrane of mammalian cells upon irradiation, forms a platform into which Bax inserts, oligomerizes and functionalizes as a pore. We posit conceptualization of ceramide as a membrane-based stress calibrator, driving membrane macrodomain organization, which in mitochondria regulates intensity of Bax-induced MOMP, and is pharmacologically tractable in vitro and in vivo. PMID:21695182

Functional Effect of Pim1 Depends upon Intracellular Localization in Human Cardiac Progenitor Cells

PubMed Central

Samse, Kaitlen; Emathinger, Jacqueline; Hariharan, Nirmala; Quijada, Pearl; Ilves, Kelli; Völkers, Mirko; Ormachea, Lucia; De La Torre, Andrea; Orogo, Amabel M.; Alvarez, Roberto; Din, Shabana; Mohsin, Sadia; Monsanto, Megan; Fischer, Kimberlee M.; Dembitsky, Walter P.; Gustafsson, Åsa B.; Sussman, Mark A.

2015-01-01

Human cardiac progenitor cells (hCPC) improve heart function after autologous transfer in heart failure patients. Regenerative potential of hCPCs is severely limited with age, requiring genetic modification to enhance therapeutic potential. A legacy of work from our laboratory with Pim1 kinase reveals effects on proliferation, survival, metabolism, and rejuvenation of hCPCs in vitro and in vivo. We demonstrate that subcellular targeting of Pim1 bolsters the distinct cardioprotective effects of this kinase in hCPCs to increase proliferation and survival, and antagonize cellular senescence. Adult hCPCs isolated from patients undergoing left ventricular assist device implantation were engineered to overexpress Pim1 throughout the cell (PimWT) or targeted to either mitochondrial (Mito-Pim1) or nuclear (Nuc-Pim1) compartments. Nuc-Pim1 enhances stem cell youthfulness associated with decreased senescence-associated β-galactosidase activity, preserved telomere length, reduced expression of p16 and p53, and up-regulation of nucleostemin relative to PimWT hCPCs. Alternately, Mito-Pim1 enhances survival by increasing expression of Bcl-2 and Bcl-XL and decreasing cell death after H2O2 treatment, thereby preserving mitochondrial integrity superior to PimWT. Mito-Pim1 increases the proliferation rate by up-regulation of cell cycle modulators Cyclin D, CDK4, and phospho-Rb. Optimal stem cell traits such as proliferation, survival, and increased youthful properties of aged hCPCs are enhanced after targeted Pim1 localization to mitochondrial or nuclear compartments. Targeted Pim1 overexpression in hCPCs allows for selection of the desired phenotypic properties to overcome patient variability and improve specific stem cell characteristics. PMID:25882843

Functional Effect of Pim1 Depends upon Intracellular Localization in Human Cardiac Progenitor Cells.

PubMed

Samse, Kaitlen; Emathinger, Jacqueline; Hariharan, Nirmala; Quijada, Pearl; Ilves, Kelli; Völkers, Mirko; Ormachea, Lucia; De La Torre, Andrea; Orogo, Amabel M; Alvarez, Roberto; Din, Shabana; Mohsin, Sadia; Monsanto, Megan; Fischer, Kimberlee M; Dembitsky, Walter P; Gustafsson, Åsa B; Sussman, Mark A

2015-05-29

Human cardiac progenitor cells (hCPC) improve heart function after autologous transfer in heart failure patients. Regenerative potential of hCPCs is severely limited with age, requiring genetic modification to enhance therapeutic potential. A legacy of work from our laboratory with Pim1 kinase reveals effects on proliferation, survival, metabolism, and rejuvenation of hCPCs in vitro and in vivo. We demonstrate that subcellular targeting of Pim1 bolsters the distinct cardioprotective effects of this kinase in hCPCs to increase proliferation and survival, and antagonize cellular senescence. Adult hCPCs isolated from patients undergoing left ventricular assist device implantation were engineered to overexpress Pim1 throughout the cell (PimWT) or targeted to either mitochondrial (Mito-Pim1) or nuclear (Nuc-Pim1) compartments. Nuc-Pim1 enhances stem cell youthfulness associated with decreased senescence-associated β-galactosidase activity, preserved telomere length, reduced expression of p16 and p53, and up-regulation of nucleostemin relative to PimWT hCPCs. Alternately, Mito-Pim1 enhances survival by increasing expression of Bcl-2 and Bcl-XL and decreasing cell death after H2O2 treatment, thereby preserving mitochondrial integrity superior to PimWT. Mito-Pim1 increases the proliferation rate by up-regulation of cell cycle modulators Cyclin D, CDK4, and phospho-Rb. Optimal stem cell traits such as proliferation, survival, and increased youthful properties of aged hCPCs are enhanced after targeted Pim1 localization to mitochondrial or nuclear compartments. Targeted Pim1 overexpression in hCPCs allows for selection of the desired phenotypic properties to overcome patient variability and improve specific stem cell characteristics. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Assessment of mitochondrial dysfunction-related, drug-induced hepatotoxicity in primary rat hepatocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Cong; Sekine, Shuichi, E-mail: ssekine@facult

Evidence that mitochondrial dysfunction plays a central role in drug-induced liver injury is rapidly accumulating. In contrast to physiological conditions, in which almost all adenosine triphosphate (ATP) in hepatocytes is generated in mitochondria via aerobic respiration, the high glucose content and limited oxygen supply of conventional culture systems force primary hepatocytes to generate most ATP via cytosolic glycolysis. Thus, such anaerobically poised cells are resistant to xenobiotics that impair mitochondrial function, and are not suitable to identify drugs with mitochondrial liabilities. In this study, primary rat hepatocytes were cultured in galactose-based medium, instead of the conventional glucose-based medium, and inmore » hyperoxia to improve the reliance of energy generation on aerobic respiration. Activation of mitochondria was verified by diminished cellular lactate release and increased oxygen consumption. These conditions improved sensitivity to the mitochondrial complex I inhibitor rotenone. Since oxidative stress is also a general cause of mitochondrial impairment, cells were exposed to test compounds in the presence of transferrin to increase the generation of reactive oxygen species via increased uptake of iron. Finally, 14 compounds with reported mitochondrial liabilities were tested to validate this new drug-induced mitochondrial toxicity assay. Overall, the culture of primary rat hepatocytes in galactose, hyperoxia and transferrin is a useful model for the identification of mitochondrial dysfunction-related drug-induced hepatotoxicity. - Highlights: • Drug-induced mitochondrial toxicity was evaluated using primary rat hepatocytes. • Galactose and hyperoxia could activate OXPHOS in primary rat hepatocytes. • Cells with enhanced OXPHOS exhibit improved sensitivity to mitochondrial toxins. • Transferrin potentiate mitochondrial toxicity via increased ROS production.« less

Decreasing mitochondrial fission diminishes vascular smooth muscle cell migration and ameliorates intimal hyperplasia

PubMed Central

Wang, Li; Yu, Tianzheng; Lee, Hakjoo; O'Brien, Dawn K.; Sesaki, Hiromi; Yoon, Yisang

2015-01-01

Aims Vascular smooth muscle cell (VSMC) migration in response to arterial wall injury is a critical process in the development of intimal hyperplasia. Cell migration is an energy-demanding process that is predicted to require mitochondrial function. Mitochondria are morphologically dynamic, undergoing continuous shape change through fission and fusion. However, the role of mitochondrial morphology in VSMC migration is not well understood. The aim of the study is to understand how mitochondrial fission contributes to VSMC migration and provides its in vivo relevance in the mouse model of intimal hyperplasia. Methods and results In primary mouse VSMCs, the chemoattractant PDGF induced mitochondrial shortening through the mitochondrial fission protein dynamin-like protein 1 (DLP1)/Drp1. Perturbation of mitochondrial fission by expressing the dominant-negative mutant DLP1-K38A or by DLP1 silencing greatly decreased PDGF-induced lamellipodia formation and VSMC migration, indicating that mitochondrial fission is an important process in VSMC migration. PDGF induced an augmentation of mitochondrial energetics as well as ROS production, both of which were found to be necessary for VSMC migration. Mechanistically, the inhibition of mitochondrial fission induced an increase of mitochondrial inner membrane proton leak in VSMCs, abrogating the PDGF-induced energetic enhancement and an ROS increase. In an in vivo model of intimal hyperplasia, transgenic mice expressing DLP1-K38A displayed markedly reduced ROS levels and neointima formation in response to femoral artery wire injury. Conclusions Mitochondrial fission is an integral process in cell migration, and controlling mitochondrial fission can limit VSMC migration and the pathological intimal hyperplasia by altering mitochondrial energetics and ROS levels. PMID:25587046

Opposite effects of statins on mitochondria of cardiac and skeletal muscles: a ‘mitohormesis’ mechanism involving reactive oxygen species and PGC-1

PubMed Central

Bouitbir, Jamal; Charles, Anne-Laure; Echaniz-Laguna, Andoni; Kindo, Michel; Daussin, Frédéric; Auwerx, Johan; Piquard, François; Geny, Bernard; Zoll, Joffrey

2012-01-01

Aims Statins protect against cardiovascular-related mortality but induce skeletal muscle toxicity. To investigate mechanisms of statins, we tested the hypothesis that statins optimized cardiac mitochondrial function but impaired vulnerable skeletal muscle by inducing different level of reactive oxygen species (ROS). Methods and results In atrium of patients treated with statins, ROS production was decreased and oxidative capacities were enhanced together with an extensive augmentation of mRNAs expression of peroxisome proliferator-activated receptor gamma co-activator (PGC-1) family. However, in deltoid biopsies from patients with statin-induced muscular myopathy, oxidative capacities were decreased together with ROS increase and a collapse of PGC-1 mRNA expression. Several animal and cell culture experiments were conducted and showed by using ROS scavengers that ROS production was the triggering factor responsible of atorvastatin-induced activation of mitochondrial biogenesis pathway and improvement of antioxidant capacities in heart. Conversely, in skeletal muscle, the large augmentation of ROS production following treatment induced mitochondrial impairments, and reduced mitochondrial biogenesis mechanisms. Quercetin, an antioxidant molecule, was able to counteract skeletal muscle deleterious effects of atorvastatin in rat. Conclusion Our findings identify statins as a new activating factor of cardiac mitochondrial biogenesis and antioxidant capacities, and suggest the importance of ROS/PGC-1 signalling pathway as a key element in regulation of mitochondrial function in cardiac as well as skeletal muscles. PMID:21775390

Effect of excess iron on oxidative stress and gluconeogenesis through hepcidin during mitochondrial dysfunction.

PubMed

Lee, Hyo Jung; Choi, Joo Sun; Lee, Hye Ja; Kim, Won-Ho; Park, Sang Ick; Song, Jihyun

2015-12-01

Excessive tissue iron levels are a risk factor for insulin resistance and type 2 diabetes, which are associated with alterations in iron metabolism. However, the mechanisms underlying this association are not well understood. This study used human liver SK-HEP-1 cells to examine how excess iron induces mitochondrial dysfunction and how hepcidin controls gluconeogenesis. Excess levels of reactive oxygen species (ROS) and accumulated iron due to iron overload induced mitochondrial dysfunction, leading to a decrease in cellular adenosine triphosphate content and cytochrome c oxidase III expression, with an associated increase in gluconeogenesis. Disturbances in mitochondrial function caused excess iron deposition and unbalanced expression of iron metabolism-related proteins such as hepcidin, ferritin H and ferroportin during the activation of p38 mitogen-activated protein kinase (MAPK) and CCAAT/enhancer-binding protein alpha (C/EBPα), which are responsible for increased phosphoenolpyruvate carboxykinase expression. Desferoxamine and n-acetylcysteine ameliorated these deteriorations by inhibiting p38 MAPK and C/EBPα activity through iron chelation and ROS scavenging activity. Based on experiments using hepcidin shRNA and hepcidin overexpression, the activation of hepcidin affects ROS generation and iron deposition, which disturbs mitochondrial function and causes an imbalance in iron metabolism and increased gluconeogenesis. Repression of hepcidin activity can reverse these changes. Our results demonstrate that iron overload is associated with mitochondrial dysfunction and that together they can cause abnormal hepatic gluconeogenesis. Hepcidin expression may modulate this disorder by regulating ROS generation and iron deposition. Copyright © 2015 Elsevier Inc. All rights reserved.

Creatine Enhances Mitochondrial-Mediated Oligodendrocyte Survival After Demyelinating Injury

PubMed Central

Nanescu, Sonia E.

2017-01-01

Chronic oligodendrocyte loss, which occurs in the demyelinating disorder multiple sclerosis (MS), contributes to axonal dysfunction and neurodegeneration. Current therapies are able to reduce MS severity, but do not prevent transition into the progressive phase of the disease, which is characterized by chronic neurodegeneration. Therefore, pharmacological compounds that promote oligodendrocyte survival could be beneficial for neuroprotection in MS. Here, we investigated the role of creatine, an organic acid involved in adenosine triphosphate (ATP) buffering, in oligodendrocyte function. We found that creatine increased mitochondrial ATP production directly in oligodendrocyte lineage cell cultures and exerted robust protection on oligodendrocytes by preventing cell death in both naive and lipopolysaccharide-treated mixed glia. Moreover, lysolecithin-mediated demyelination in mice deficient in the creatine-synthesizing enzyme guanidinoacetate-methyltransferase (Gamt) did not affect oligodendrocyte precursor cell recruitment, but resulted in exacerbated apoptosis of regenerated oligodendrocytes in central nervous system (CNS) lesions. Remarkably, creatine administration into Gamt-deficient and wild-type mice with demyelinating injury reduced oligodendrocyte apoptosis, thereby increasing oligodendrocyte density and myelin basic protein staining in CNS lesions. We found that creatine did not affect the recruitment of macrophages/microglia into lesions, suggesting that creatine affects oligodendrocyte survival independently of inflammation. Together, our results demonstrate a novel function for creatine in promoting oligodendrocyte viability during CNS remyelination. SIGNIFICANCE STATEMENT We report that creatine enhances oligodendrocyte mitochondrial function and protects against caspase-dependent oligodendrocyte apoptosis during CNS remyelination. This work has important implications for the development of therapeutic targets for diseases characterized by oligodendrocyte death, including multiple sclerosis. PMID:28069926

Mitochondrial targeting of the human peptide methionine sulfoxide reductase (MSRA), an enzyme involved in the repair of oxidized proteins.

PubMed

Hansel, Alfred; Kuschel, Lioba; Hehl, Solveig; Lemke, Cornelius; Agricola, Hans-Jürgen; Hoshi, Toshinori; Heinemann, Stefan H

2002-06-01

Peptide methionine sulfoxide reductase (MSRA) catalyzes the reduction of methionine sulfoxide to methionine. This widely expressed enzyme constitutes an important repair mechanism for oxidatively damaged proteins, which accumulate during the manifestation of certain degenerative diseases and aging processes. In addition, it is discussed to be involved in regulatory processes. Here we address the question of how the enzyme's diverse functions are reflected in its subcellular localization. Using fusions of the human version of MSRA with the enhanced green fluorescence protein expressed in various mammalian cell lines, we show a distinct localization at mitochondria. The N-terminal 23 amino acid residues contain the signal for this mitochondrial targeting. Activity tests showed that they are not required for enzyme function. Mitochondrial localization of native MSRA in mouse and rat liver slices was verified with an MSRA-specific antibody by using immunohistochemical methods. The protein was located in the mitochondrial matrix, as demonstrated by using pre-embedding immunostaining and electron microscopy. Mitochondria are the major source of reactive oxygen species (ROS). Therefore, MSRA has to be considered an important means for the general reduction of ROS release from mitochondria.

Pharmacological approaches to restore mitochondrial function

PubMed Central

Andreux, Pénélope A.; Houtkooper, Riekelt H.; Auwerx, Johan

2014-01-01

Mitochondrial dysfunction is not only a hallmark of rare inherited mitochondrial disorders, but is also implicated in age-related diseases, including those that affect the metabolic and nervous system, such as type 2 diabetes and Parkinson’s disease. Numerous pathways maintain and/or restore proper mitochondrial function, including mitochondrial biogenesis, mitochondrial dynamics, mitophagy, and the mitochondrial unfolded protein response. New and powerful phenotypic assays in cell-based models, as well as multicellular organisms, have been developed to explore these different aspects of mitochondrial function. Modulating mitochondrial function has therefore emerged as an attractive therapeutic strategy for a range of diseases, which has spurred active drug discovery efforts in this area. PMID:23666487

Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function

PubMed Central

Ciron, C.; Lengacher, S.; Dusonchet, J.; Aebischer, P.; Schneider, B.L.

2012-01-01

Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity. PMID:22246294

Neurometabolic mechanisms for memory enhancement and neuroprotection of methylene blue

PubMed Central

Rojas, Julio C.; Bruchey, Aleksandra K.; Gonzalez-Lima, F.

2011-01-01

This paper provides the first review of the memory-enhancing and neuroprotective metabolic mechanisms of action of methylene blue in vivo. These mechanisms have important implications as a new neurobiological approach to improve normal memory and to treat memory impairment and neurodegeneration associated with mitochondrial dysfunction. Methylene blue’s action is unique because its neurobiological effects are not determined by regular drug-receptor interactions or drug-response paradigms. Methylene blue shows a hormetic dose-response, with opposite effects at low and high doses. At low doses, methylene blue is an electron cycler in the mitochondrial electron transport chain, with unparalleled antioxidant and cell respiration-enhancing properties that affect the function of the nervous system in a versatile manner. A major role of the respiratory enzyme cytochrome oxidase on the memory-enhancing effects of methylene blue is supported by available data. The memory-enhancing effects have been associated with improvement of memory consolidation in a network-specific and use-dependent fashion. In addition, low doses of methylene blue have also been used for neuroprotection against mitochondrial dysfunction in humans and experimental models of disease. The unique auto-oxidizing property of methylene blue and its pleiotropic effects on a number of tissue oxidases explain its potent neuroprotective effects at low doses. The evidence reviewed supports a mechanistic role of low-dose methylene blue as a promising and safe intervention for improving memory and for the treatment of acute and chronic conditions characterized by increased oxidative stress, neurodegeneration and memory impairment. PMID:22067440

ALS-associated mutation SOD1G93A leads to abnormal mitochondrial dynamics in osteocytes.

PubMed

Wang, Huan; Yi, Jianxun; Li, Xuejun; Xiao, Yajuan; Dhakal, Kamal; Zhou, Jingsong

2018-01-01

While the death of motor neuron is a pathological hallmark of amyotrophic lateral sclerosis (ALS), defects in other cell types or organs may also actively contribute to ALS disease progression. ALS patients experience progressive skeletal muscle wasting that may not only exacerbate neuronal degeneration, but likely has a significant impact on bone function. In our previous published study, we have discovered severe bone loss in an ALS mouse model with overexpression of ALS-associated mutation SOD1 G93A (G93A). Here we further provide a mechanistic understanding of the bone loss in ALS animal and cellular models. Combining mitochondrial fluorescent indicators and confocal live cell imaging, we discovered abnormalities in mitochondrial network and dynamics in primary osteocytes derived from the same ALS mouse model G93A. Those mitochondrial defects occur in ALS mice after the onset of neuromuscular symptoms, indicating that mitochondria in bone cells respond to muscle atrophy during ALS disease progression. To examine whether ALS mutation has a direct contribution to mitochondrial dysfunction independent of muscle atrophy, we evaluated mitochondrial morphology and motility in cultured osteocytes (MLO-Y4) with overexpression of mitochondrial targeted SOD1 G93A . Compared with osteocytes overexpressing the wild type SOD1 as a control, the SOD1 G93A osteocytes showed similar defects in mitochondrial network and dynamic as that of the primary osteocytes derived from the ALS mouse model. In addition, we further discovered that overexpression of SOD1 G93A enhanced the expression level of dynamin-related protein 1 (Drp1), a key protein promoting mitochondrial fission activity, and reduced the expression level of optic atrophy protein 1 (OPA1), a key protein related to mitochondrial fusion. A specific mitochondrial fission inhibitor (Mdivi-1) partially reversed the effect of SOD1 G93A on mitochondrial network and dynamics, indicating that SOD1 G93A likely promotes mitochondrial fission, but suppresses the fusion activity. Our data provide the first evidence that mitochondria show abnormality in osteocytes derived from an ALS mouse model. The accumulation of mutant SOD1 G93A protein inside mitochondria directly causes dysfunction in mitochondrial dynamics in cultured MLO-Y4 osteocytes. In addition, the ALS mutation SOD1 G93A -mediated dysfunction in mitochondrial dynamics is associated with an enhanced apoptosis in osteocytes, which could be a potential mechanism underlying the bone loss during ALS progression. Copyright © 2017 Elsevier Inc. All rights reserved.

Mitochondrial Vulnerability and Increased Susceptibility to Nutrient-Induced Cytotoxicity in Fibroblasts from Leigh Syndrome French Canadian Patients

PubMed Central

Burelle, Yan; Thompson Legault, Julie; Boucher, Gabrielle; Morin, Charles; Coderre, Lise; Des Rosiers, Christine

2015-01-01

Mutations in LRPPRC are responsible for the French Canadian variant of Leigh Syndrome (LSFC), a severe disorder characterized biochemically by a tissue-specific deficiency of cytochrome c oxidase (COX) and clinically by the occurrence of severe and deadly acidotic crises. Factors that precipitate these crises remain unclear. To better understand the physiopathology and identify potential treatments, we performed a comprehensive analysis of mitochondrial function in LSFC and control fibroblasts. Furthermore, we have used this cell-based model to screen for conditions that promote premature cell death in LSFC cells and test the protective effect of ten interventions targeting well-defined aspects of mitochondrial function. We show that, despite maintaining normal ATP levels, LSFC fibroblasts present several mitochondrial functional abnormalities under normal baseline conditions, which likely impair their capacity to respond to stress. This includes mitochondrial network fragmentation, impaired oxidative phosphorylation capacity, lower membrane potential, increased sensitivity to Ca2+-induced permeability transition, but no changes in reactive oxygen species production. We also show that LSFC fibroblasts display enhanced susceptibility to cell death when exposed to palmitate, an effect that is potentiated by high lactate, while high glucose or acidosis alone or in combination were neutral. Furthermore, we demonstrate that compounds that are known to promote flux through the electron transport chain independent of phosphorylation (methylene blue, dinitrophenol), or modulate fatty acid (L-carnitine) or Krebs cycle metabolism (propionate) are protective, while antioxidants (idebenone, N-acetyl cysteine, resveratrol) exacerbate palmitate plus lactate-induced cell death. Collectively, beyond highlighting multiple alterations in mitochondrial function and increased susceptibility to nutrient-induced cytotoxicity in LSFC fibroblasts, these results raise questions about the nature of the diets, particularly excess fat intake, as well as on the use of antioxidants in patients with LSFC and, possibly, other COX defects. PMID:25835550

Effect of CCS on the accumulation of FALS SOD1 mutant-containing aggregates and on mitochondrial translocation of SOD1 mutants: implication of a free radical hypothesis.

PubMed

Kim, Ha Kun; Chung, Youn Wook; Chock, P Boon; Yim, Moon B

2011-05-15

Missense mutations of SOD1 are linked to familial amyotrophic lateral sclerosis (FALS) through a yet-to-be identified toxic-gain-of-function. One of the proposed mechanisms involves enhanced aggregate formation. However, a recent study showed that dual transgenic mice overexpressing both G93A and CCS copper chaperone (G93A/CCS) exhibit no SOD1-positive aggregates yet show accelerated FALS symptoms with enhanced mitochondrial pathology compared to G93A mice. Using a dicistronic mRNA to simultaneously generate hSOD1 mutants, G93A, A4V and G85R, and hCCS in AAV293 cells, we revealed: (i) CCS is degraded primarily via a macroautophagy pathway. It forms a stable heterodimer with inactive G85R, and via its novel copper chaperone-independent molecular chaperone activity facilitates G85R degradation via a macroautophagy-mediated pathway. For active G93A and A4V, CCS catalyzes their maturation to form active and soluble homodimers. (ii) CCS reduces, under non-oxidative conditions, yet facilitates in the presence of H(2)O(2), mitochondrial translocation of inactive SOD1 mutants. These results, together with previous reports showing FALS SOD1 mutants enhanced free radical-generating activity, provide a mechanistic explanation for the observations with G93A/CCS dual transgenic mice and suggest that free radical generation by FALS SOD1, enhanced by CCS, may, in part, be responsible for the FALS SOD1 mutant-linked aggregation, mitochondrial translocation, and degradation. Published by Elsevier Inc.

Improved health-span and lifespan in mtDNA mutator mice treated with the mitochondrially targeted antioxidant SkQ1

PubMed Central

Shabalina, Irina G.; Vyssokikh, Mikhail Yu.; Gibanova, Natalia; Csikasz, Robert I.; Edgar, Daniel; Hallden-Waldemarson, Anne; Rozhdestvenskaya, Zinaida; Bakeeva, Lora E.; Vays, Valeria B.; Pustovidko, Antonina V.; Skulachev, Maxim V.; Cannon, Barbara; Skulachev, Vladimir P.; Nedergaard, Jan

2017-01-01

MtDNA mutator mice exhibit marked features of premature aging. We find that these mice treated from age of ≈100 days with the mitochondria-targeted antioxidant SkQ1 showed a delayed appearance of traits of aging such as kyphosis, alopecia, lowering of body temperature, body weight loss, as well as ameliorated heart, kidney and liver pathologies. These effects of SkQ1 are suggested to be related to an alleviation of the effects of an enhanced reactive oxygen species (ROS) level in mtDNA mutator mice: the increased mitochondrial ROS released due to mitochondrial mutations probably interact with polyunsaturated fatty acids in cardiolipin, releasing malondialdehyde and 4-hydroxynonenal that form protein adducts and thus diminishes mitochondrial functions. SkQ1 counteracts this as it scavenges mitochondrial ROS. As the results, the normal mitochondrial ultrastructure is preserved in liver and heart; the phosphorylation capacity of skeletal muscle mitochondria as well as the thermogenic capacity of brown adipose tissue is also improved. The SkQ1-treated mice live significantly longer (335 versus 290 days). These data may be relevant in relation to treatment of mitochondrial diseases particularly and the process of aging in general. PMID:28209927

Molecular bases of caloric restriction regulation of neuronal synaptic plasticity.

PubMed

Fontán-Lozano, Angela; López-Lluch, Guillermo; Delgado-García, José María; Navas, Placido; Carrión, Angel Manuel

2008-10-01

Aging is associated with the decline of cognitive properties. This situation is magnified when neurodegenerative processes associated with aging appear in human patients. Neuronal synaptic plasticity events underlie cognitive properties in the central nervous system. Caloric restriction (CR; either a decrease in food intake or an intermittent fasting diet) can extend life span and increase disease resistance. Recent studies have shown that CR can have profound effects on brain function and vulnerability to injury and disease. Moreover, CR can stimulate the production of new neurons from stem cells (neurogenesis) and can enhance synaptic plasticity, which modulate pain sensation, enhance cognitive function, and may increase the ability of the brain to resist aging. The beneficial effects of CR appear to be the result of a cellular stress response stimulating the production of proteins that enhance neuronal plasticity and resistance to oxidative and metabolic insults; they include neurotrophic factors, neurotransmitter receptors, protein chaperones, and mitochondrial biosynthesis regulators. In this review, we will present and discuss the effect of CR in synaptic processes underlying analgesia and cognitive improvement in healthy, sick, and aging animals. We will also discuss the possible role of mitochondrial biogenesis induced by CR in regulation of neuronal synaptic plasticity.

Sirt3 binds to and deacetylates mitochondrial pyruvate carrier 1 to enhance its activity.

PubMed

Liang, Lei; Li, Qingguo; Huang, Liyong; Li, Dawei; Li, Xinxiang

2015-12-25

Mitochondrial pyruvate carrier (MPC), composed of MPC1 and MPC2, can modulate pyruvate oxidation in mitochondrial and MPC1 expression correlates with poor prognosis of multiple cancers. Here, we reported that MPC1 is acetylated and its main acetylation sites are: K45 and K46. Sirt3 binds to and deacetylates MPC1. High glucose decreases MPC1 acetylation level by increasing Sirt3-MPC1 binding. Furthermore, acetylation mimic mutation of MPC1 reduces it activity and abolishes its function in inhibition of colon cancer cell growth. These results reveal a novel post-translational regulation of MPC1 by Sirt3, which is important for its activity and colon cancer cell growth. Copyright © 2015 Elsevier Inc. All rights reserved.

Peroxisome Proliferator-Activated Receptor (PPAR) γ and PPARα Agonists Modulate Mitochondrial Fusion-Fission Dynamics: Relevance to Reactive Oxygen Species (ROS)-Related Neurodegenerative Disorders?

PubMed Central

Zolezzi, Juan M.; Silva-Alvarez, Carmen; Ordenes, Daniela; Godoy, Juan A.; Carvajal, Francisco J.; Santos, Manuel J.; Inestrosa, Nibaldo C.

2013-01-01

Recent studies showed that the activation of the retinoid X receptor, which dimerizes with peroxisome proliferator-activated receptors (PPARs), leads to an enhanced clearance of Aβ from the brain of transgenic mice model of Alzheimer’s disease (AD), because an increased expression of apolipoprotein E and it main transporters. However, the effects observed must involve additional underlying mechanisms that have not been yet explored. Several studies conducted in our laboratory suggest that part of the effects observed for the PPARs agonist might involves mitochondrial function and, particularly, mitochondrial dynamics. In the present study we assessed the effects of oxidative stress challenge on mitochondrial morphology and mitochondrial dynamics-related proteins in hippocampal neurons. Using immunofluorescence, we evaluated the PPARγ co-activator 1α (PGC-1α), dynamin related protein 1 (DRP1), mitochondrial fission protein 1 (FIS1), and mitochondrial length, in order to determine if PPARs agonist pre-treatment is able to protect mitochondrial population from hippocampal neurons through modulation of the mitochondrial fusion-fission events. Our results suggest that both a PPARγ agonist (ciglitazone) and a PPARα agonist (WY 14.643) are able to protect neurons by modulating mitochondrial fusion and fission, leading to a better response of neurons to oxidative stress, suggesting that a PPAR based therapy could acts simultaneously in different cellular components. Additionally, our results suggest that PGC-1α and mitochondrial dynamics should be further studied in future therapy research oriented to ameliorate neurodegenerative disorders, such as AD. PMID:23675519

Inhibitor-induced oxidation of the nucleus and cytosol in Arabidopsis thaliana: implications for organelle to nucleus retrograde signalling

PubMed Central

Karpinska, Barbara; Alomrani, Sarah Owdah

2017-01-01

Concepts of organelle-to-nucleus signalling pathways are largely based on genetic screens involving inhibitors of chloroplast and mitochondrial functions such as norflurazon, lincomycin (LINC), antimycin A (ANT) and salicylhydroxamic acid. These inhibitors favour enhanced cellular oxidation, but their precise effects on the cellular redox state are unknown. Using the in vivo reduction–oxidation (redox) reporter, roGFP2, inhibitor-induced changes in the glutathione redox potentials of the nuclei and cytosol were measured in Arabidopsis thaliana root, epidermal and stomatal guard cells, together with the expression of nuclear-encoded chloroplast and mitochondrial marker genes. All the chloroplast and mitochondrial inhibitors increased the degree of oxidation in the nuclei and cytosol. However, inhibitor-induced oxidation was less marked in stomatal guard cells than in epidermal or root cells. Moreover, LINC and ANT caused a greater oxidation of guard cell nuclei than the cytosol. Chloroplast and mitochondrial inhibitors significantly decreased the abundance of LHCA1 and LHCB1 transcripts. The levels of WHY1, WHY3 and LEA5 transcripts were increased in the presence of inhibitors. Chloroplast inhibitors decreased AOXA1 mRNA levels, while mitochondrial inhibitors had the opposite effect. Inhibitors that are used to characterize retrograde signalling pathways therefore have similar general effects on cellular redox state and gene expression. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’. PMID:28808105

The evolution of a mechanism of cell suicide.

PubMed

Blackstone, N W; Green, D R

1999-01-01

In the vertebrates, programmed cell death or apoptosis frequently involves the relocalization of mitochondrial cytochrome c to the cytoplasm. This prominent role in the regulation of apoptosis is in addition to the primary function of cytochrome c in the mitochondrial electron transport chain. These seemingly divergent roles become plausible when considering the symbiotic origin of the mitochondrion. Symbiosis involves conflicts between levels of selection, in this case between the primitive host cell and the protomitochondria. In an aerobic environment, selection on the protomitochondria may have favored routine manipulations of the host cell's phenotype using products and by-products of oxidative phosphorylation, in particular reactive oxygen species (ROS). Blocking the mitochondrial electron transport chain by removing cytochrome c enhances the production of ROS; thus cytochrome c release by protomitochondria may have altered the host cell's phenotype via enhanced ROS production. Subsequently, this signaling pathway may have been refined by selection so that cytochrome c itself became the trigger for changes in the host's phenotype. A mechanism of apoptosis in metazoans may thus be a vestige of evolutionary conflicts within the eukaryotic cell.

Phosphatase and Tensin Homolog Deleted on Chromosome 10 (PTEN) Signaling Regulates Mitochondrial Biogenesis and Respiration via Estrogen-related Receptor α (ERRα)*

PubMed Central

Li, Yang; He, Lina; Zeng, Ni; Sahu, Divya; Cadenas, Enrique; Shearn, Colin; Li, Wei; Stiles, Bangyan L.

2013-01-01

Mitochondrial abnormalities are associated with cancer development, yet how oncogenic signals affect mitochondrial functions has not been fully understood. In this study, we investigate the relationship between mitochondrial alterations and PI3K/protein kinase B (AKT) signaling activation using hepatocytes and liver tissues as our experimental models. We show here that liver-specific deletion of Pten, which leads to activation of PI3K/AKT, is associated with elevated oxidative stress, increased mitochondrial mass, and augmented respiration accompanied by enhanced glycolysis. Consistent with these observations, estrogen-related receptor α (ERRα), an orphan nuclear receptor known for its role in mitochondrial biogenesis, is up-regulated in the absence of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Our pharmacological and genetic studies show that PI3K/AKT activity regulates the expression of ERRα and mitochondrial biogenesis/respiration. Furthermore, cAMP-response element-binding protein, as a downstream target of AKT, plays a role in the regulation of ERRα, independent of PKA signaling. ERRα regulates reactive oxygen species production, and ERRα knockdown attenuates proliferation and colony-forming potential in Pten-null hepatocytes. Finally, analysis of clinical datasets from liver tissues showed a negative correlation between expressions of ERRα and PTEN in patients with liver cancer. Therefore, this study has established a previously unrecognized link between a growth signal and mitochondrial metabolism. PMID:23836899

Expression of a truncated form of the endoplasmic reticulum chaperone protein, σ1 receptor, promotes mitochondrial energy depletion and apoptosis.

PubMed

Shioda, Norifumi; Ishikawa, Kiyoshi; Tagashira, Hideaki; Ishizuka, Toru; Yawo, Hiromu; Fukunaga, Kohji

2012-07-06

The σ1 receptor (σ(1)R) regulates endoplasmic reticulum (ER)/mitochondrial interorganellar Ca(2+) mobilization through the inositol 1,4,5-trisphosphate receptor (IP(3)R). Here, we observed that expression of a novel splice variant of σ(1)R, termed short form σ(1)R (σ(1)SR), has a detrimental effect on mitochondrial energy production and cell survival. σ(1)SR mRNA lacks 47 ribonucleotides encoding exon 2, resulting in a frameshift and formation of a truncated receptor. σ(1)SR localizes primarily in the ER at perinuclear regions and forms a complex with σ(1)R but not with IP(3)R in the mitochondrion-associated ER membrane. Overexpression of both σ(1)R and the truncated isoform promotes mitochondrial elongation with increased ER mitochondrial contact surface. σ(1)R overexpression increases the efficiency of mitochondrial Ca(2+) uptake in response to IP(3)R-driven stimuli, whereas σ(1)SR overexpression reduces it. Most importantly, σ(1)R promotes ATP production via increased mitochondrial Ca(2+) uptake, promoting cell survival in the presence of ER stress. By contrast, σ(1)SR suppresses ATP production following ER stress, enhancing cell death. Taken together, the newly identified σ(1)SR isoform interferes with σ(1)R function relevant to mitochondrial energy production under ER stress conditions, promoting cellular apoptosis.

p53-PGC-1α Pathway Mediates Oxidative Mitochondrial Damage and Cardiomyocyte Necrosis Induced by Monoamine Oxidase-A Upregulation: Role in Chronic Left Ventricular Dysfunction in Mice

PubMed Central

Villeneuve, Christelle; Guilbeau-Frugier, Céline; Sicard, Pierre; Lairez, Olivier; Ordener, Catherine; Duparc, Thibaut; De Paulis, Damien; Couderc, Bettina; Spreux-Varoquaux, Odile; Tortosa, Florence; Garnier, Anne; Knauf, Claude; Valet, Philippe; Borchi, Elisabetta; Nediani, Chiara; Gharib, Abdallah; Ovize, Michel; Delisle, Marie-Bernadette; Mialet-Perez, Jeanne

2013-01-01

Abstract Aims: Oxidative stress and mitochondrial dysfunction participate together in the development of heart failure (HF). mRNA levels of monoamine oxidase-A (MAO-A), a mitochondrial enzyme that produces hydrogen peroxide (H2O2), increase in several models of cardiomyopathies. Therefore, we hypothesized that an increase in cardiac MAO-A could cause oxidative stress and mitochondrial damage, leading to cardiac dysfunction. In the present study, we evaluated the consequences of cardiac MAO-A augmentation on chronic oxidative damage, cardiomyocyte survival, and heart function, and identified the intracellular pathways involved. Results: We generated transgenic (Tg) mice with cardiac-specific MAO-A overexpression. Tg mice displayed cardiac MAO-A activity levels similar to those found in HF and aging. As expected, Tg mice showed a significant decrease in the cardiac amounts of the MAO-A substrates serotonin and norepinephrine. This was associated with enhanced H2O2 generation in situ and mitochondrial DNA oxidation. As a consequence, MAO-A Tg mice demonstrated progressive loss of cardiomyocytes by necrosis and ventricular failure, which were prevented by chronic treatment with the MAO-A inhibitor clorgyline and the antioxidant N-acetyl-cystein. Interestingly, Tg hearts exhibited p53 accumulation and downregulation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial function. This was concomitant with cardiac mitochondrial ultrastructural defects and ATP depletion. In vitro, MAO-A adenovirus transduction of neonatal cardiomyocytes mimicked the results in MAO-A Tg mice, triggering oxidative stress-dependent p53 activation, leading to PGC-1α downregulation, mitochondrial impairment, and cardiomyocyte necrosis. Innovation and Conclusion: We provide the first evidence that MAO-A upregulation in the heart causes oxidative mitochondrial damage, p53-dependent repression of PGC-1α, cardiomyocyte necrosis, and chronic ventricular dysfunction. Antioxid. Redox Signal. 18, 5–18. PMID:22738191

Mono-epoxy-tocotrienol-α enhances wound healing in diabetic mice and stimulates in vitro angiogenesis and cell migration.

PubMed

Xu, Cheng; Bentinger, Magnus; Savu, Octavian; Moshfegh, Ali; Sunkari, Vivekananda; Dallner, Gustav; Swiezewska, Ewa; Catrina, Sergiu-Bogdan; Brismar, Kerstin; Tekle, Michael

2017-01-01

Diabetes mellitus is characterized by hyperglycemia and capillary hypoxia that causes excessive production of free radicals and impaired antioxidant defense, resulting in oxidative stress and diabetes complications such as impaired wound healing. We have previously shown that modified forms of tocotrienols possess beneficial effects on the biosynthesis of the mevalonate pathway lipids including increase in mitochondrial CoQ. The aim of this study is to investigate the effects of mono-epoxy-tocotrienol-α on in vitro and in vivo wound healing models as well as its effects on mitochondrial function. Gene profiling analysis and gene expression studies on HepG2 cells and human dermal fibroblasts were performed by microarray and qPCR, respectively. In vitro wound healing using human fibroblasts was studied by scratch assay and in vitro angiogenesis using human dermal microvascular endothelial cells was studied by the tube formation assay. In vivo wound healing was performed in the diabetic db/db mouse model. For the study of mitochondrial functions and oxygen consumption rate Seahorse XF-24 was employed. In vitro, significant increase in wound closure and cell migration (p<0.05) both in normal and high glucose and in endothelial tube formation (angiogenesis) (p<0.005) were observed. Microarray profiling analysis showed a 20-fold increase of KIF26A gene expression and 11-fold decrease of lanosterol synthase expression. Expression analysis by qPCR showed significant increase of the growth factors VEGFA and PDGFB. The epoxidated compound induced a significantly higher basal and reserve mitochondrial capacity in both HDF and HepG2 cells. Additionally, in vivo wound healing in db/db mice, demonstrated a small but significant enhancement on wound healing upon local application of the compound compared to treatment with vehicle alone. Mono-epoxy-tocotrienol-α seems to possess beneficial effects on wound healing by increasing the expression of genes involved in cell growth, motility and angiogenes as well as on mitochondrial function. Copyright © 2017 Elsevier Inc. All rights reserved.

Global analyses of Ceratocystis cacaofunesta mitochondria: from genome to proteome.

PubMed

Ambrosio, Alinne Batista; do Nascimento, Leandro Costa; Oliveira, Bruno V; Teixeira, Paulo José P L; Tiburcio, Ricardo A; Toledo Thomazella, Daniela P; Leme, Adriana F P; Carazzolle, Marcelo F; Vidal, Ramon O; Mieczkowski, Piotr; Meinhardt, Lyndel W; Pereira, Gonçalo A G; Cabrera, Odalys G

2013-02-11

The ascomycete fungus Ceratocystis cacaofunesta is the causal agent of wilt disease in cacao, which results in significant economic losses in the affected producing areas. Despite the economic importance of the Ceratocystis complex of species, no genomic data are available for any of its members. Given that mitochondria play important roles in fungal virulence and the susceptibility/resistance of fungi to fungicides, we performed the first functional analysis of this organelle in Ceratocystis using integrated "omics" approaches. The C. cacaofunesta mitochondrial genome (mtDNA) consists of a single, 103,147-bp circular molecule, making this the second largest mtDNA among the Sordariomycetes. Bioinformatics analysis revealed the presence of 15 conserved genes and 37 intronic open reading frames in C. cacaofunesta mtDNA. Here, we predicted the mitochondrial proteome (mtProt) of C. cacaofunesta, which is comprised of 1,124 polypeptides - 52 proteins that are mitochondrially encoded and 1,072 that are nuclearly encoded. Transcriptome analysis revealed 33 probable novel genes. Comparisons among the Gene Ontology results of the predicted mtProt of C. cacaofunesta, Neurospora crassa and Saccharomyces cerevisiae revealed no significant differences. Moreover, C. cacaofunesta mitochondria were isolated, and the mtProt was subjected to mass spectrometric analysis. The experimental proteome validated 27% of the predicted mtProt. Our results confirmed the existence of 110 hypothetical proteins and 7 novel proteins of which 83 and 1, respectively, had putative mitochondrial localization. The present study provides the first partial genomic analysis of a species of the Ceratocystis genus and the first predicted mitochondrial protein inventory of a phytopathogenic fungus. In addition to the known mitochondrial role in pathogenicity, our results demonstrated that the global function analysis of this organelle is similar in pathogenic and non-pathogenic fungi, suggesting that its relevance in the lifestyle of these organisms should be based on a small number of specific proteins and/or with respect to differential gene regulation. In this regard, particular interest should be directed towards mitochondrial proteins with unknown function and the novel protein that might be specific to this species. Further functional characterization of these proteins could enhance our understanding of the role of mitochondria in phytopathogenicity.

Global analyses of Ceratocystis cacaofunesta mitochondria: from genome to proteome

PubMed Central

2013-01-01

Background The ascomycete fungus Ceratocystis cacaofunesta is the causal agent of wilt disease in cacao, which results in significant economic losses in the affected producing areas. Despite the economic importance of the Ceratocystis complex of species, no genomic data are available for any of its members. Given that mitochondria play important roles in fungal virulence and the susceptibility/resistance of fungi to fungicides, we performed the first functional analysis of this organelle in Ceratocystis using integrated “omics” approaches. Results The C. cacaofunesta mitochondrial genome (mtDNA) consists of a single, 103,147-bp circular molecule, making this the second largest mtDNA among the Sordariomycetes. Bioinformatics analysis revealed the presence of 15 conserved genes and 37 intronic open reading frames in C. cacaofunesta mtDNA. Here, we predicted the mitochondrial proteome (mtProt) of C. cacaofunesta, which is comprised of 1,124 polypeptides - 52 proteins that are mitochondrially encoded and 1,072 that are nuclearly encoded. Transcriptome analysis revealed 33 probable novel genes. Comparisons among the Gene Ontology results of the predicted mtProt of C. cacaofunesta, Neurospora crassa and Saccharomyces cerevisiae revealed no significant differences. Moreover, C. cacaofunesta mitochondria were isolated, and the mtProt was subjected to mass spectrometric analysis. The experimental proteome validated 27% of the predicted mtProt. Our results confirmed the existence of 110 hypothetical proteins and 7 novel proteins of which 83 and 1, respectively, had putative mitochondrial localization. Conclusions The present study provides the first partial genomic analysis of a species of the Ceratocystis genus and the first predicted mitochondrial protein inventory of a phytopathogenic fungus. In addition to the known mitochondrial role in pathogenicity, our results demonstrated that the global function analysis of this organelle is similar in pathogenic and non-pathogenic fungi, suggesting that its relevance in the lifestyle of these organisms should be based on a small number of specific proteins and/or with respect to differential gene regulation. In this regard, particular interest should be directed towards mitochondrial proteins with unknown function and the novel protein that might be specific to this species. Further functional characterization of these proteins could enhance our understanding of the role of mitochondria in phytopathogenicity. PMID:23394930

TrxR2 deficiencies promote chondrogenic differentiation and induce apoptosis of chondrocytes through mitochondrial reactive oxygen species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Jidong; Xu, Jing; Fei, Yao

Thioredoxin reductase 2 (TrxR2) is a selenium (Se) containing protein. Se deficiency is associated with an endemic osteoarthropathy characterized by impaired cartilage formation. It is unclear whether TrxR2 have roles in cartilage function. We examined the effects of TrxR2 on chondrogenic ATDC5 cells through shRNA-mediated gene silencing of TrxR2. We demonstrated TrxR2 deficiencies could enhance chondrogenic differentiation and apoptosis of ATDC5 cells. TrxR2 deficiencies increased accumulation of cartilage glycosaminoglycans (GAGs) and mineralization. TrxR2 deficiencies also stimulated expression of extracellular (ECM) gene including Collagen II and Aggrecan. The enhanced chondrogenic properties were further confirmed by activation of Akt signaling which aremore » required for chondrogenesis. In addition, TrxR2 deficiencies promoted chondrocyte proliferation through acceleration of cell cycle progression by increase in both S and G2/M phase cell distribution accompanied with induction of parathyroid hormone-related protein (PTHrP). Moreover, TrxR2 deficiencies induced chondrocyte death via apoptosis and increased cell sensitivity to exogenous oxidative stress. Furthermore, TrxR2 deficiencies induced emission of mitochondrial reactive oxygen species (ROS) without alteration of mitochondrial membrane potential and intracellular ATP content. Finally, treatment of TrxR2 deficiency cells with N-acetylcysteine (NAC) inhibited mitochondrial ROS production and chondrocyte apoptosis. NAC also prevented chondrogenic differentiation of TrxR2 deficiency cells by suppression of ECM gene expression, GAGs accumulation and mineralization, as well as attenuation of Akt signaling. Thus, TrxR2-mediated mitochondrial integrity is indispensable for chondrogenic differentiation of ATDC5 cells. TrxR2 deficiency-induced impaired proliferation and death of chondrocytes may be the pathological mechanism of the osteoarthropathy due to Se deficiency. Notably, this study also uncover the roles of mitochondrial ROS which could stimulate cartilage ECM synthesis that offer novel insights for development of therapeutic agent to prevent cartilage degeneration in human disease. - Highlights: • TrxR2 deficiencies enhance chondrogenic differentiation. • TrxR2 deficiencies stimulate chondrocyte proliferation. • TrxR2 deficiencies induce chondrocyte apoptosis. • TrxR2 deficiencies increase emission of mitochondrial ROS. • Mitochondrial ROS regulate chondrocyte proliferation, differentiation, and apoptosis.« less

Enhanced mitochondrial complex gene function and reduced liver size may mediate improved feed efficiency of beef cattle during compensatory growth

USDA-ARS?s Scientific Manuscript database

Growing ruminants maintained under dietary restriction for extended periods will exhibit compensatory growth when reverted to ad libitum feeding. This period of compensatory growth is associated with increased feed efficiency, lower basal energy requirements, and changes in circulating concentration...

Bardoxolone-methyl inhibits migration and metabolism in MCF7 cells.

PubMed

Refaat, Alaa; Pararasa, Chathyan; Arif, Muhammed; Brown, James E P; Carmichael, Amtul; Ali, Sameh S; Sakurai, Hiroaki; Griffiths, Helen R

2017-02-01

Bardoxolone-methyl (BAR) is reported to have anti-inflammatory, anti-proliferative and anti-fibrotic effects. BAR activates Nrf2 and may ameliorate oxidative stress through induction of antioxidant genes. However, off-target effects, probably concentration and NFkB-dependent, have limited the clinical use of BAR. Nrf2 regulates expression of antioxidant and mitochondrial genes and has been proposed as a target for both obesity and breast cancer. Therefore, we explored whether BAR can alter migration and proliferation in the MCF7 cell line and whether metabolic function is affected by BAR. Incubation with BAR caused a time-dependent migratory inhibition and an associated decrease in mitochondrial respiration. Both migratory and mitochondrial inhibition by BAR were further enhanced in the presence of fatty acids. In addition to the activation of Nrf2, BAR altered the expression of target mRNA GCLC and UCP1. After 24 h, BAR inhibited both glycolytic capacity, reserve (p < 0.05) and oxidative phosphorylation (p < 0.001) with an associated increase in mitochondrial ROS and loss of intracellular glutathione in MCF7 cells; however, impairment of mitochondrial activity was prevented by N-acetyl cysteine. The fatty acid, palmitate, increased mitochondrial ROS, impaired migration and oxidative phosphorylation but palmitate toxicity towards MCF7 could not be inhibited by N-acetyl cysteine suggesting that they exert effects through different pathways. BAR-activated AKT, induced DNA damage and inhibited cell proliferation. When the proteasome was inhibited, there was loss of BAR-mediated changes in p65 phosphorylation and SOD2 expression suggesting non-canonical NFkB signaling effects. These data suggest that BAR-induced ROS are important in inhibiting MCF7 migration and metabolism by negatively affecting glycolytic capacity and mitochondrial function.

Mitochondrial function at extreme high altitude.

PubMed

Murray, Andrew J; Horscroft, James A

2016-03-01

At high altitude, barometric pressure falls and with it inspired P(O2), potentially compromising O2 delivery to the tissues. With sufficient acclimatisation, the erythropoietic response increases red cell mass such that arterial O2 content (C(aO2)) is restored; however arterial P(O2)(P(aO2)) remains low, and the diffusion of O2 from capillary to mitochondrion is impaired. Mitochondrial respiration and aerobic capacity are thus limited, whilst reactive oxygen species (ROS) production increases. Restoration of P(aO2) with supplementary O2 does not fully restore aerobic capacity in acclimatised individuals, possibly indicating a peripheral impairment. With prolonged exposure to extreme high altitude (>5500 m), muscle mitochondrial volume density falls, with a particular loss of the subsarcolemmal population. It is not clear whether this represents acclimatisation or deterioration, but it does appear to be regulated, with levels of the mitochondrial biogenesis factor PGC-1α falling, and shows similarities to adapted Tibetan highlanders. Qualitative changes in mitochondrial function also occur, and do so at more moderate high altitudes with shorter periods of exposure. Electron transport chain complexes are downregulated, possibly mitigating the increase in ROS production. Fatty acid oxidation capacity is decreased and there may be improvements in biochemical coupling at the mitochondrial inner membrane that enhance O2 efficiency. Creatine kinase expression falls, possibly impairing high-energy phosphate transfer from the mitochondria to myofibrils. In climbers returning from the summit of Everest, cardiac energetic reserve (phosphocreatine/ATP) falls, but skeletal muscle energetics are well preserved, possibly supporting the notion that mitochondrial remodelling is a core feature of acclimatisation to extreme high altitude. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

LL-37 attenuates inflammatory impairment via mTOR signaling-dependent mitochondrial protection.

PubMed

Sun, Wenyan; Zheng, Yan; Lu, Zhuoyang; Wang, Hui; Feng, Zhihui; Wang, Juan; Xiao, Shengxiang; Liu, Feng; Liu, Jiankang

2014-09-01

The human cationic antimicrobial protein LL-37 is a multifunctional host defense peptide with a wide range of immunomodulatory activities. Previous work has shown that LL-37 exerts both pro- and anti-inflammatory effects. The role of mitochondria in the skin inflammatory effects of LL-37 has not been well studied. Therefore, our aim was to investigate the immunomodulatory effect of LL-37 in HaCaT cells and to delineate the underlying mechanisms related to mitochondrial function. Immunohistochemistry results from tissue microarrays showed strong cytoplasmic LL-37 staining in inflammatory cells in chronic dermatic inflammation. Using exogenous LL-37 stimulation and LL-37 knockdown and overexpression, LL-37 was demonstrated to dramatically reduce the mRNA levels and protein secretion of inflammatory cytokines including IL-6, IL-8, IL-1α and tumor necrosis factor-α (TNF-α), which are induced by lipopolysaccharides (LPS). The anti-inflammatory effects of LL-37 are dependent upon its ability to increase mitochondrial biogenesis and to maintain mitochondrial homeostasis. Furthermore, we observed that LL-37 enhances the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK1/2) and mammalian target of rapamycin (mTOR). The mTOR inhibitor rapamycin can neutralize the protective effects of LL-37 on mitochondria. In conclusion, these results suggest that high LL-37 expression levels correlate with chronic skin inflammation; mitochondrial dysfunction occurs in HaCaT cells during inflammation; and LL-37 attenuates inflammatory impairment by stimulating mitochondrial biogenesis and protecting mitochondrial function, which are dependent upon mTOR signaling. These findings provide new insights into targeting mitochondria with LL-37 to prevent skin inflammatory reactions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Accelerated recovery of renal mitochondrial and tubule homeostasis with SIRT1/PGC-1α activation following ischemia-reperfusion injury.

PubMed

Funk, Jason A; Schnellmann, Rick G

2013-12-01

Kidney ischemia-reperfusion (I/R) injury elicits cellular injury in the proximal tubule, and mitochondrial dysfunction is a pathological consequence of I/R. Promoting mitochondrial biogenesis (MB) as a repair mechanism after injury may offer a unique strategy to restore both mitochondrial and organ function. Rats subjected to bilateral renal pedicle ligation for 22 min were treated once daily with the SIRT1 activator SRT1720 (5mg/kg) starting 24h after reperfusion until 72h-144 h. SIRT1 expression was elevated in the renal cortex of rats after I/R+vehicle treatment (IRV), but was associated with less nuclear localization. SIRT1 expression was even further augmented and nuclear localization was restored in the kidneys of rats after I/R+SRT1720 treatment (IRS). PGC-1α was elevated at 72 h-144 h in IRV and IRS kidneys; however, SRT1720 treatment induced deacetylation of PGC-1α, a marker of activation. Mitochondrial proteins ATP synthase β, COX I, and NDUFB8, as well as mitochondrial respiration, were diminished 24h-144 h in IRV rats, but were partially or fully restored in IRS rats. Urinary kidney injury molecule-1 (KIM-1) was persistently elevated in both IRV and IRS rats; however, KIM-1 tissue expression was attenuated in IRS rats. Additionally, sustained loss of Na(+),K(+)-ATPase expression and basolateral localization and elevated vimentin in IRV rats was normalized in IRS rats, suggesting restoration of a differentiated, polarized tubule epithelium. The results suggest that SRT1720 treatment expedited recovery of mitochondrial protein expression and function by enhancing MB, which was associated with faster proximal tubule repair. Targeting MB may offer unique therapeutic strategy following ischemic injury. © 2013. Published by Elsevier Inc. All rights reserved.

BID links ferroptosis to mitochondrial cell death pathways.

PubMed

Neitemeier, Sandra; Jelinek, Anja; Laino, Vincenzo; Hoffmann, Lena; Eisenbach, Ina; Eying, Roman; Ganjam, Goutham K; Dolga, Amalia M; Oppermann, Sina; Culmsee, Carsten

2017-08-01

Ferroptosis has been defined as an oxidative and iron-dependent pathway of regulated cell death that is distinct from caspase-dependent apoptosis and established pathways of death receptor-mediated regulated necrosis. While emerging evidence linked features of ferroptosis induced e.g. by erastin-mediated inhibition of the X c - system or inhibition of glutathione peroxidase 4 (Gpx4) to an increasing number of oxidative cell death paradigms in cancer cells, neurons or kidney cells, the biochemical pathways of oxidative cell death remained largely unclear. In particular, the role of mitochondrial damage in paradigms of ferroptosis needs further investigation. In the present study, we find that erastin-induced ferroptosis in neuronal cells was accompanied by BID transactivation to mitochondria, loss of mitochondrial membrane potential, enhanced mitochondrial fragmentation and reduced ATP levels. These hallmarks of mitochondrial demise are also established features of oxytosis, a paradigm of cell death induced by X c - inhibition by millimolar concentrations of glutamate. Bid knockout using CRISPR/Cas9 approaches preserved mitochondrial integrity and function, and mediated neuroprotective effects against both, ferroptosis and oxytosis. Furthermore, the BID-inhibitor BI-6c9 inhibited erastin-induced ferroptosis, and, in turn, the ferroptosis inhibitors ferrostatin-1 and liproxstatin-1 prevented mitochondrial dysfunction and cell death in the paradigm of oxytosis. These findings show that mitochondrial transactivation of BID links ferroptosis to mitochondrial damage as the final execution step in this paradigm of oxidative cell death. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Mitochondrial-targeted DNA delivery using a DF-MITO-Porter, an innovative nano carrier with cytoplasmic and mitochondrial fusogenic envelopes

NASA Astrophysics Data System (ADS)

Yamada, Yuma; Kawamura, Eriko; Harashima, Hideyoshi

2012-08-01

Mitochondrial gene therapy has the potential for curing a variety of diseases that are associated with mitochondrial DNA mutations and/or defects. To achieve this, it will be necessary to deliver therapeutic agents into the mitochondria in diseased cells. A number of mitochondrial drug delivery systems have been reported to date. However, reports of mitochondrial-targeted DNA delivery are limited. To achieve this, the therapeutic agent must be taken up by the cell (1), after which, the multi-processes associated with intracellular trafficking must be sophisticatedly regulated so as to release the agent from the endosome and deliver it to the cytosol (2) and to pass through the mitochondrial membrane (3). We report herein on the mitochondrial delivery of oligo DNA as a model therapeutic using a Dual Function (DF)-MITO-Porter, an innovative nano carrier designed for mitochondrial delivery. The critical structural elements of the DF-MITO-Porter include mitochondria-fusogenic inner envelopes and endosome-fusogenic outer envelopes, modified with octaarginine which greatly assists in cellular uptake. Inside the cell, the carrier passes through the endosomal and mitochondrial membranes via step-wise membrane fusion. When the oligo DNA was packaged in the DF-MITO-Porter, cellular uptake efficiency was strongly enhanced. Intracellular observation using confocal laser scanning microscopy showed that the DF-MITO-Porter was effectively released from endosomes. Moreover, the findings confirmed that the mitochondrial targeting activity of the DF-MITO-Porter was significantly higher than that of a carrier without outer endosome-fusogenic envelopes. These results support the conclusion that mitochondrial-targeted DNA delivery using a DF-MITO-Porter can be achieved when intracellular trafficking is optimally regulated.

Skeletal muscle mitochondria: a major player in exercise, health and disease.

PubMed

Russell, Aaron P; Foletta, Victoria C; Snow, Rod J; Wadley, Glenn D

2014-04-01

Maintaining skeletal muscle mitochondrial content and function is important for sustained health throughout the lifespan. Exercise stimulates important key stress signals that control skeletal mitochondrial biogenesis and function. Perturbations in mitochondrial content and function can directly or indirectly impact skeletal muscle function and consequently whole-body health and wellbeing. This review will describe the exercise-stimulated stress signals and molecular mechanisms positively regulating mitochondrial biogenesis and function. It will then discuss the major myopathies, neuromuscular diseases and conditions such as diabetes and ageing that have dysregulated mitochondrial function. Finally, the impact of exercise and potential pharmacological approaches to improve mitochondrial function in diseased populations will be discussed. Exercise activates key stress signals that positively impact major transcriptional pathways that transcribe genes involved in skeletal muscle mitochondrial biogenesis, fusion and metabolism. The positive impact of exercise is not limited to younger healthy adults but also benefits skeletal muscle from diseased populations and the elderly. Impaired mitochondrial function can directly influence skeletal muscle atrophy and contribute to the risk or severity of disease conditions. Pharmacological manipulation of exercise-induced pathways that increase skeletal muscle mitochondrial biogenesis and function in critically ill patients, where exercise may not be possible, may assist in the treatment of chronic disease. This review highlights our understanding of how exercise positively impacts skeletal muscle mitochondrial biogenesis and function. Exercise not only improves skeletal muscle mitochondrial health but also enables us to identify molecular mechanisms that may be attractive targets for therapeutic manipulation. This article is part of a Special Issue entitled Frontiers of mitochondrial research. Copyright © 2013 Elsevier B.V. All rights reserved.

Inhibition of MCU forces extramitochondrial adaptations governing physiological and pathological stress responses in heart

PubMed Central

Rasmussen, Tyler P.; Wu, Yuejin; Joiner, Mei-ling A.; Koval, Olha M.; Wilson, Nicholas R.; Luczak, Elizabeth D.; Wang, Qinchuan; Chen, Biyi; Gao, Zhan; Zhu, Zhiyong; Wagner, Brett A.; Soto, Jamie; McCormick, Michael L.; Kutschke, William; Weiss, Robert M.; Yu, Liping; Boudreau, Ryan L.; Abel, E. Dale; Zhan, Fenghuang; Spitz, Douglas R.; Buettner, Garry R.; Song, Long-Sheng; Zingman, Leonid V.; Anderson, Mark E.

2015-01-01

Myocardial mitochondrial Ca2+ entry enables physiological stress responses but in excess promotes injury and death. However, tissue-specific in vivo systems for testing the role of mitochondrial Ca2+ are lacking. We developed a mouse model with myocardial delimited transgenic expression of a dominant negative (DN) form of the mitochondrial Ca2+ uniporter (MCU). DN-MCU mice lack MCU-mediated mitochondrial Ca2+ entry in myocardium, but, surprisingly, isolated perfused hearts exhibited higher O2 consumption rates (OCR) and impaired pacing induced mechanical performance compared with wild-type (WT) littermate controls. In contrast, OCR in DN-MCU–permeabilized myocardial fibers or isolated mitochondria in low Ca2+ were not increased compared with WT, suggesting that DN-MCU expression increased OCR by enhanced energetic demands related to extramitochondrial Ca2+ homeostasis. Consistent with this, we found that DN-MCU ventricular cardiomyocytes exhibited elevated cytoplasmic [Ca2+] that was partially reversed by ATP dialysis, suggesting that metabolic defects arising from loss of MCU function impaired physiological intracellular Ca2+ homeostasis. Mitochondrial Ca2+ overload is thought to dissipate the inner mitochondrial membrane potential (ΔΨm) and enhance formation of reactive oxygen species (ROS) as a consequence of ischemia-reperfusion injury. Our data show that DN-MCU hearts had preserved ΔΨm and reduced ROS during ischemia reperfusion but were not protected from myocardial death compared with WT. Taken together, our findings show that chronic myocardial MCU inhibition leads to previously unanticipated compensatory changes that affect cytoplasmic Ca2+ homeostasis, reprogram transcription, increase OCR, reduce performance, and prevent anticipated therapeutic responses to ischemia-reperfusion injury. PMID:26153425

Curcumin analog EF24 induces apoptosis via ROS-dependent mitochondrial dysfunction in human colorectal cancer cells.

PubMed

He, Guodong; Feng, Chen; Vinothkumar, Rajamanickam; Chen, Weiqian; Dai, Xuanxuan; Chen, Xi; Ye, Qingqing; Qiu, Chenyu; Zhou, Huiping; Wang, Yi; Liang, Guang; Xie, Yubo; Wu, Wei

2016-12-01

Colorectal cancer is the most commonly diagnosed malignancy with high mortality rates worldwide. Improved therapeutic strategies with minimal adverse side effects are urgently needed. In this study, the anti-tumor effects of EF24, a novel analog of the natural compound curcumin, were evaluated in colorectal cancer cells. The anti-tumor activity of EF24 on human colon cancer lines (HCT-116, SW-620, and HT-29) was determined by measures of cell cycle arrest, apoptosis, and mitochondrial function. The contribution of ROS in the EF24-induced anti-tumor activity was evaluated by measures of H 2 O 2 and pretreatment with an ROS scavenger, NAC. The findings indicated that EF24 treatment dose-dependently inhibited cell viability and caused cell cycle arrest at G2/M phase in all the tested colon cancer cell lines. Furthermore, we demonstrated that EF24 treatment induced apoptosis effectively via enhancing intracellular accumulation of ROS in both HCT-116 and SW-620 cells, but with moderate effects in HT-29 cells. We found that EF24 treatment decreased the mitochondrial membrane potential in the colon cancer cells, leading to the release of mitochondrial cytochrome c. Also, EF24 induced activation of caspases 9 and 3, causing decreased Bcl-2 protein expression and Bcl-2/Bax ratio. Pretreatment with NAC, a ROS scavenger, abrogated the EF24-induced cell death, apoptosis, cell cycle arrest, and mitochondrial dysfunction, suggesting an upstream ROS generation which was responsible for the anticancer effects of EF24. Our findings support an anticancer mechanism by which EF24 enhanced ROS accumulation in colon cancer cells, thereby resulting in mitochondrial membrane collapse and activated intrinsic apoptotic signaling. Thus, EF24 could be a potential candidate for therapeutic application of colon cancer.

The Alzheimer's Disease Mitochondrial Cascade Hypothesis: Progress and Perspectives

PubMed Central

Swerdlow, Russell H.; Burns, Jeffrey M.; Khan, Shaharyar M.

2013-01-01

Ten years ago we first proposed the Alzheimer's disease (AD) mitochondrial cascade hypothesis. This hypothesis maintains gene inheritance defines an individual's baseline mitochondrial function; inherited and environmental factors determine rates at which mitochondrial function changes over time; and baseline mitochondrial function and mitochondrial change rates influence AD chronology. Our hypothesis unequivocally states in sporadic, late-onset AD, mitochondrial function affects amyloid precursor protein (APP) expression, APP processing, or beta amyloid (Aβ) accumulation and argues if an amyloid cascade truly exists, mitochondrial function triggers it. We now review the state of the mitochondrial cascade hypothesis, and discuss it in the context of recent AD biomarker studies, diagnostic criteria, and clinical trials. Our hypothesis predicts biomarker changes reflect brain aging, new AD definitions clinically stage brain aging, and removing brain Aβ at any point will marginally impact cognitive trajectories. Our hypothesis, therefore, offers unique perspective into what sporadic, late-onset AD is and how to best treat it. PMID:24071439

Direct effects of mitochondrial dysfunction on poor bone health in Leigh syndrome.

PubMed

Kato, Hiroki; Han, Xu; Yamaza, Haruyoshi; Masuda, Keiji; Hirofuji, Yuta; Sato, Hiroshi; Pham, Thanh Thi Mai; Taguchi, Tomoaki; Nonaka, Kazuaki

2017-11-04

Mitochondrial diseases are the result of aberrant mitochondrial function caused by mutations in either nuclear or mitochondrial DNA. Poor bone health has recently been suggested as a symptom of mitochondrial diseases; however, a direct link between decreased mitochondrial function and poor bone health in mitochondrial disease has not been demonstrated. In this study, stem cells from human exfoliated deciduous teeth (SHED) were isolated from a child with Leigh syndrome (LS), a mitochondrial disease, and the effects of decreased mitochondrial function on poor bone health were analyzed. Compared with control SHED, LS SHED displayed decreased osteoblastic differentiation and calcium mineralization. The intracellular and mitochondrial calcium levels were lower in LS SHED than in control SHED. Furthermore, the mitochondrial activity of LS SHED was decreased compared with control SHED both with and without osteoblastic differentiation. Our results indicate that decreased osteoblast differentiation potential and osteoblast function contribute to poor bone health in mitochondrial diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Induction of Mitochondrial Dysfunction and Oxidative Damage by Antibiotic Drug Doxycycline Enhances the Responsiveness of Glioblastoma to Chemotherapy

PubMed Central

Tan, Qian; Yan, Xiaoqiong; Song, Lin; Yi, Hongxiang; Li, Ping; Sun, Guobin; Yu, Danfang; Li, Le; Zeng, Zheng; Guo, Zhenli

2017-01-01

Background Inducing mitochondrial dysfunction has been recently demonstrated to be an alternative therapeutic strategy for cancer treatment. Doxycycline is an antibiotic that has been shown to have anti-cancer activities in various cancers by way of targeting mitochondria. In this work, we examined whether doxycycline can be repurposed for glioblastoma treatment. Material/Methods The effects of doxycycline on the growth, survival, and mitochondrial metabolisms of glioblastoma were investigated. The efficacy of a combination of doxycycline with temozolomide was examined using xenograft mouse model in total number of 40 mice. Results Doxycycline targeted glioblastoma cell lines, regardless of their origin, through inhibiting growth and inducing cell death, accompanied by a significant decrease in proliferating cell nuclear antigen (PCNA) and increase in cleaved caspase-3. In addition, doxycycline significantly sensitized glioblastoma cell response to temozolomide in vitro and in vivo. Mechanistically, doxycycline disrupted mitochondrial functions through decreasing mitochondrial membrane potential and mitochondrial respiration. Inducing mitochondrial dysfunctions by using doxycycline led to energy crisis, oxidative stress, and damage as shown by the decreased levels of ATP and the elevated levels of mitochondrial superoxide, intracellular ROS, 8-OHdG, protein carbonylation, and lipid peroxidation. An antioxidant N-acetyl-L-cysteine (NAC) significantly abolished the anti-proliferative and pro-apoptotic effects of doxycycline, demonstrating that doxycycline acts on glioblastoma via inducing oxidative stress. Conclusions In our study, we show that the antibiotic doxycycline is effective in targeting glioblastoma through inducing mitochondrial dysfunctions and oxidative stress. Our work also demonstrated the importance of mitochondrial metabolism in glioblastoma. PMID:28842551

Induction of Mitochondrial Dysfunction and Oxidative Damage by Antibiotic Drug Doxycycline Enhances the Responsiveness of Glioblastoma to Chemotherapy.

PubMed

Tan, Qian; Yan, Xiaoqiong; Song, Lin; Yi, Hongxiang; Li, Ping; Sun, Guobin; Yu, Danfang; Li, Le; Zeng, Zheng; Guo, Zhenlin

2017-08-26

BACKGROUND Inducing mitochondrial dysfunction has been recently demonstrated to be an alternative therapeutic strategy for cancer treatment. Doxycycline is an antibiotic that has been shown to have anti-cancer activities in various cancers by way of targeting mitochondria. In this work, we examined whether doxycycline can be repurposed for glioblastoma treatment. MATERIAL AND METHODS The effects of doxycycline on the growth, survival, and mitochondrial metabolisms of glioblastoma were investigated. The efficacy of a combination of doxycycline with temozolomide was examined using xenograft mouse model in total number of 40 mice. RESULTS Doxycycline targeted glioblastoma cell lines, regardless of their origin, through inhibiting growth and inducing cell death, accompanied by a significant decrease in proliferating cell nuclear antigen (PCNA) and increase in cleaved caspase-3. In addition, doxycycline significantly sensitized glioblastoma cell response to temozolomide in vitro and in vivo. Mechanistically, doxycycline disrupted mitochondrial functions through decreasing mitochondrial membrane potential and mitochondrial respiration. Inducing mitochondrial dysfunctions by using doxycycline led to energy crisis, oxidative stress, and damage as shown by the decreased levels of ATP and the elevated levels of mitochondrial superoxide, intracellular ROS, 8-OHdG, protein carbonylation, and lipid peroxidation. An antioxidant N-acetyl-L-cysteine (NAC) significantly abolished the anti-proliferative and pro-apoptotic effects of doxycycline, demonstrating that doxycycline acts on glioblastoma via inducing oxidative stress. CONCLUSIONS In our study, we show that the antibiotic doxycycline is effective in targeting glioblastoma through inducing mitochondrial dysfunctions and oxidative stress. Our work also demonstrated the importance of mitochondrial metabolism in glioblastoma.

MicroRNA-210 regulates mitochondrial free radical response to hypoxia and krebs cycle in cancer cells by targeting iron sulfur cluster protein ISCU.

PubMed

Favaro, Elena; Ramachandran, Anassuya; McCormick, Robert; Gee, Harriet; Blancher, Christine; Crosby, Meredith; Devlin, Cecilia; Blick, Christopher; Buffa, Francesca; Li, Ji-Liang; Vojnovic, Borivoj; Pires das Neves, Ricardo; Glazer, Peter; Iborra, Francisco; Ivan, Mircea; Ragoussis, Jiannis; Harris, Adrian L

2010-04-26

Hypoxia in cancers results in the upregulation of hypoxia inducible factor 1 (HIF-1) and a microRNA, hsa-miR-210 (miR-210) which is associated with a poor prognosis. In human cancer cell lines and tumours, we found that miR-210 targets the mitochondrial iron sulfur scaffold protein ISCU, required for assembly of iron-sulfur clusters, cofactors for key enzymes involved in the Krebs cycle, electron transport, and iron metabolism. Down regulation of ISCU was the major cause of induction of reactive oxygen species (ROS) in hypoxia. ISCU suppression reduced mitochondrial complex 1 activity and aconitase activity, caused a shift to glycolysis in normoxia and enhanced cell survival. Cancers with low ISCU had a worse prognosis. Induction of these major hallmarks of cancer show that a single microRNA, miR-210, mediates a new mechanism of adaptation to hypoxia, by regulating mitochondrial function via iron-sulfur cluster metabolism and free radical generation.

Protective Mechanisms of Mitochondria and Heart Function in Diabetes

PubMed Central

Tocchetti, Carlo G.; Bhatt, Niraj; Paolocci, Nazareno; Cortassa, Sonia

2015-01-01

Abstract Significance: The heart depends on continuous mitochondrial ATP supply and maintained redox balance to properly develop force, particularly under increased workload. During diabetes, however, myocardial energetic-redox balance is perturbed, contributing to the systolic and diastolic dysfunction known as diabetic cardiomyopathy (DC). Critical Issues: How these energetic and redox alterations intertwine to influence the DC progression is still poorly understood. Excessive bioavailability of both glucose and fatty acids (FAs) play a central role, leading, among other effects, to mitochondrial dysfunction. However, where and how this nutrient excess affects mitochondrial and cytoplasmic energetic/redox crossroads remains to be defined in greater detail. Recent Advances: We review how high glucose alters cellular redox balance and affects mitochondrial DNA. Next, we address how lipid excess, either stored in lipid droplets or utilized by mitochondria, affects performance in diabetic hearts by influencing cardiac energetic and redox assets. Finally, we examine how the reciprocal energetic/redox influence between mitochondrial and cytoplasmic compartments shapes myocardial mechanical activity during the course of DC, focusing especially on the glutathione and thioredoxin systems. Future Directions: Protecting mitochondria from losing their ability to generate energy, and to control their own reactive oxygen species emission is essential to prevent the onset and/or to slow down DC progression. We highlight mechanisms enforced by the diabetic heart to counteract glucose/FAs surplus-induced damage, such as lipid storage, enhanced mitochondria-lipid droplet interaction, and upregulation of key antioxidant enzymes. Learning more on the nature and location of mechanisms sheltering mitochondrial functions would certainly help in further optimizing therapies for human DC. Antioxid. Redox Signal. 22, 1563–1586. PMID:25674814

Fasting and refeeding differentially regulate NLRP3 inflammasome activation in human subjects.

PubMed

Traba, Javier; Kwarteng-Siaw, Miriam; Okoli, Tracy C; Li, Jessica; Huffstutler, Rebecca D; Bray, Amanda; Waclawiw, Myron A; Han, Kim; Pelletier, Martin; Sauve, Anthony A; Siegel, Richard M; Sack, Michael N

2015-11-03

Activation of the NLRP3 inflammasome is associated with metabolic dysfunction, and intermittent fasting has been shown to improve clinical presentation of NLRP3 inflammasome-linked diseases. As mitochondrial perturbations, which function as a damage-associated molecular pattern, exacerbate NLRP3 inflammasome activation, we investigated whether fasting blunts inflammasome activation via sirtuin-mediated augmentation of mitochondrial integrity. We performed a clinical study of 19 healthy volunteers. Each subject underwent a 24-hour fast and then was fed a fixed-calorie meal. Blood was drawn during the fasted and fed states and analyzed for NRLP3 inflammasome activation. We enrolled an additional group of 8 healthy volunteers to assess the effects of the sirtuin activator, nicotinamide riboside, on NLRP3 inflammasome activation. In the fasting/refeeding study, individuals showed less NLRP3 inflammasome activation in the fasted state compared with that in refed conditions. In a human macrophage line, depletion of the mitochondrial-enriched sirtuin deacetylase SIRT3 increased NLRP3 inflammasome activation in association with excessive mitochondrial ROS production. Furthermore, genetic and pharmacologic SIRT3 activation blunted NLRP3 activity in parallel with enhanced mitochondrial function in cultured cells and in leukocytes extracted from healthy volunteers and from refed individuals but not in those collected during fasting. Together, our data indicate that nutrient levels regulate the NLRP3 inflammasome, in part through SIRT3-mediated mitochondrial homeostatic control. Moreover, these results suggest that deacetylase-dependent inflammasome attenuation may be amenable to targeting in human disease. ClinicalTrials.gov NCT02122575 and NCT00442195. Division of Intramural Research, NHLBI of the NIH.

Enhancing mitochondrial proteostasis reduces amyloid-β proteotoxicity.

PubMed

Sorrentino, Vincenzo; Romani, Mario; Mouchiroud, Laurent; Beck, John S; Zhang, Hongbo; D'Amico, Davide; Moullan, Norman; Potenza, Francesca; Schmid, Adrien W; Rietsch, Solène; Counts, Scott E; Auwerx, Johan

2017-12-14

Alzheimer's disease is a common and devastating disease characterized by aggregation of the amyloid-β peptide. However, we know relatively little about the underlying molecular mechanisms or how to treat patients with Alzheimer's disease. Here we provide bioinformatic and experimental evidence of a conserved mitochondrial stress response signature present in diseases involving amyloid-β proteotoxicity in human, mouse and Caenorhabditis elegans that involves the mitochondrial unfolded protein response and mitophagy pathways. Using a worm model of amyloid-β proteotoxicity, GMC101, we recapitulated mitochondrial features and confirmed that the induction of this mitochondrial stress response was essential for the maintenance of mitochondrial proteostasis and health. Notably, increasing mitochondrial proteostasis by pharmacologically and genetically targeting mitochondrial translation and mitophagy increases the fitness and lifespan of GMC101 worms and reduces amyloid aggregation in cells, worms and in transgenic mouse models of Alzheimer's disease. Our data support the relevance of enhancing mitochondrial proteostasis to delay amyloid-β proteotoxic diseases, such as Alzheimer's disease.

Characterization, design, and function of the mitochondrial proteome: from organs to organisms.

PubMed

Lotz, Christopher; Lin, Amanda J; Black, Caitlin M; Zhang, Jun; Lau, Edward; Deng, Ning; Wang, Yueju; Zong, Nobel C; Choi, Jeong H; Xu, Tao; Liem, David A; Korge, Paavo; Weiss, James N; Hermjakob, Henning; Yates, John R; Apweiler, Rolf; Ping, Peipei

2014-02-07

Mitochondria are a common energy source for organs and organisms; their diverse functions are specialized according to the unique phenotypes of their hosting environment. Perturbation of mitochondrial homeostasis accompanies significant pathological phenotypes. However, the connections between mitochondrial proteome properties and function remain to be experimentally established on a systematic level. This uncertainty impedes the contextualization and translation of proteomic data to the molecular derivations of mitochondrial diseases. We present a collection of mitochondrial features and functions from four model systems, including two cardiac mitochondrial proteomes from distinct genomes (human and mouse), two unique organ mitochondrial proteomes from identical genetic codons (mouse heart and mouse liver), as well as a relevant metazoan out-group (drosophila). The data, composed of mitochondrial protein abundance and their biochemical activities, capture the core functionalities of these mitochondria. This investigation allowed us to redefine the core mitochondrial proteome from organs and organisms, as well as the relevant contributions from genetic information and hosting milieu. Our study has identified significant enrichment of disease-associated genes and their products. Furthermore, correlational analyses suggest that mitochondrial proteome design is primarily driven by cellular environment. Taken together, these results connect proteome feature with mitochondrial function, providing a prospective resource for mitochondrial pathophysiology and developing novel therapeutic targets in medicine.

Mitochondrial respiration controls lysosomal function during inflammatory T cell responses

PubMed Central

Baixauli, Francesc; Acín-Pérez, Rebeca; Villarroya-Beltrí, Carolina; Mazzeo, Carla; Nuñez-Andrade, Norman; Gabandé-Rodriguez, Enrique; Dolores Ledesma, Maria; Blázquez, Alberto; Martin, Miguel Angel; Falcón-Pérez, Juan Manuel; Redondo, Juan Miguel; Enríquez, Jose Antonio; Mittelbrunn, Maria

2016-01-01

Summary The endolysosomal system is critical for the maintenance of cellular homeostasis. However, how endolysosomal compartment is regulated by mitochondrial function is largely unknown. We have generated a mouse model with defective mitochondrial function in CD4+ T lymphocytes by genetic deletion of the mitochondrial transcription factor A (Tfam). Mitochondrial respiration-deficiency impairs lysosome function, promotes p62 and sphingomyelin accumulation and disrupts endolysosomal trafficking pathways and autophagy, thus linking a primary mitochondrial dysfunction to a lysosomal storage disorder. The impaired lysosome function in Tfam-deficient cells subverts T cell differentiation toward pro-inflammatory subsets and exacerbates the in vivo inflammatory response. Restoration of NAD+ levels improves lysosome function and corrects the inflammatory defects in Tfam-deficient T cells. Our results uncover a mechanism by which mitochondria regulate lysosome function to preserve T cell differentiation and effector functions, and identify novel strategies for intervention in mitochondrial-related diseases. PMID:26299452

Mitochondrial calcium ion and membrane potential transients follow the pattern of epileptiform discharges in hippocampal slice cultures.

PubMed

Kovács, Richard; Kardos, Julianna; Heinemann, Uwe; Kann, Oliver

2005-04-27

Emerging evidence suggests that mitochondrial dysfunction contributes to the pathophysiology of epilepsy. Recurrent mitochondrial Ca2+ ion load during seizures might act on mitochondrial membrane potential (DeltaPsim) and proton motive force. By using electrophysiology and confocal laser-scanning microscopy, we investigated the effects of epileptiform activity, as induced by low-Mg2+ ion perfusion in hippocampal slice cultures, on changes in DeltaPsim and in mitochondrial Ca2+ ion concentration ([Ca2+]m). The mitochondrial compartment was identified by monitoring DeltaPsim in the soma and dendrites of patched CA3 pyramidal cells using the mitochondria-specific voltage-sensitive dye rhodamine-123 (Rh-123). Interictal activity was accompanied by localized mitochondrial depolarization that was restricted to a few mitochondria in small dendrites. In contrast, robust Rh-123 release into the cytosol was observed during seizure-like events (SLEs), indicating simultaneous depolarization of mitochondria. This was critically dependent on Ca2+ ion uptake and extrusion, because inhibition of the mitochondrial Ca2+ ion uniporter by Ru360 and the mitochondrial Na+/Ca2+ ion exchanger by 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one but not the inhibitor of mitochondrial permeability transition pore, cyclosporin A, decreased the SLE-associated mitochondrial depolarization. The Ca2+ ion dependence of simultaneous mitochondrial depolarization suggested enhanced Ca2+ ion cycling across mitochondrial membranes during epileptiform activity. Indeed, [Ca2+]m fluctuated during interictal activity in single dendrites, and these fluctuations spread over the entire mitochondrial compartment during SLEs, as revealed using mitochondria-specific dyes (rhod-2 and rhod-ff) and spatial frequency-based image analysis. These findings strengthen the hypothesis that epileptic activity results in Ca2+ ion-dependent changes in mitochondrial function that might contribute to the neuronal injury during epilepsy.

Uncoupling of oxidative phosphorylation and ATP synthase reversal within the hyperthermic heart

PubMed Central

Power, Amelia; Pearson, Nicholas; Pham, Toan; Cheung, Carlos; Phillips, Anthony; Hickey, Anthony

2014-01-01

Abstract Heart failure is a common cause of death with hyperthermia, and the exact cause of hyperthermic heart failure appears elusive. We hypothesize that the energy supply (ATP) of the heart may become impaired due to increased inner‐mitochondrial membrane permeability and inefficient oxidative phosphorylation (OXPHOS). Therefore, we assessed isolated working heart and mitochondrial function. Ex vivo working rat hearts were perfused between 37 and 43.5°C and showed break points in all functional parameters at ~40.5°C. Mitochondrial high‐resolution respirometry coupled to fluorometry was employed to determine the effects of hyperthermia on OXPHOS and mitochondrial membrane potential (ΔΨ) in vitro using a comprehensive metabolic substrate complement with isolated mitochondria. Relative to 37 and 40°C, 43°C elevated Leak O2 flux and depressed OXPHOS O2 flux and ∆Ψ. Measurement of steady‐state ATP production from mitochondria revealed decreased ATP synthesis capacity, and a negative steady‐state P:O ratio at 43°C. This approach offers a more powerful analysis of the effects of temperature on OXPHOS that cannot be measured using simple measures such as the traditional respiratory control ratio (RCR) or P:O ratio, which, respectively, can only approach 1 or 0 with inner‐membrane failure. At 40°C there was only a slight enhancement of the Leak O2 flux and this did not significantly affect ATP production rate. Therefore, during mild hyperthermia (40°C) there is no enhancement of ATP supply by mitochondria, to accompany increasing cardiac energy demands, while between this and critical hyperthermia (43°C), mitochondria become net consumers of ATP. This consumption may contribute to cardiac failure or permanent damage during severe hyperthermia. PMID:25263202

GSNOR Deficiency Enhances In Situ Skeletal Muscle Strength, Fatigue Resistance, and RyR1 S-Nitrosylation Without Impacting Mitochondrial Content and Activity

PubMed Central

Moon, Younghye; Cao, Yenong; Zhu, Jingjing; Xu, Yuanyuan; Balkan, Wayne; Buys, Emmanuel S.; Diaz, Francisca; Kerrick, W. Glenn; Hare, Joshua M.

2017-01-01

Abstract Aim: Nitric oxide (NO) plays important, but incompletely defined roles in skeletal muscle. NO exerts its regulatory effects partly though S-nitrosylation, which is balanced by denitrosylation by enzymes such as S-nitrosoglutathione reductase (GSNOR), whose functions in skeletal muscle remain to be fully deciphered. Results: GSNOR null (GSNOR−/−) tibialis anterior (TA) muscles showed normal growth and were stronger and more fatigue resistant than controls in situ. However, GSNOR−/− lumbrical muscles showed normal contractility and Ca2+ handling in vitro, suggesting important differences in GSNOR function between muscles or between in vitro and in situ environments. GSNOR−/− TA muscles exhibited normal mitochondrial content, and capillary densities, but reduced type IIA fiber content. GSNOR inhibition did not impact mitochondrial respiratory complex I, III, or IV activities. These findings argue that enhanced GSNOR−/− TA contractility is not driven by changes in mitochondrial content or activity, fiber type, or blood vessel density. However, loss of GSNOR led to RyR1 hypernitrosylation, which is believed to increase muscle force output under physiological conditions. cGMP synthesis by soluble guanylate cyclase (sGC) was decreased in resting GSNOR−/− muscle and was more responsive to agonist (DETANO, BAY 41, and BAY 58) stimulation, suggesting that GSNOR modulates cGMP production in skeletal muscle. Innovation: GSNOR may act as a “brake” on skeletal muscle contractile performance under physiological conditions by modulating nitrosylation/denitrosylation balance. Conclusions: GSNOR may play important roles in skeletal muscle contractility, RyR1 S-nitrosylation, fiber type specification, and sGC activity. Antioxid. Redox Signal. 26, 165–181. PMID:27412893

Notch3/Akt signaling contributes to OSM-induced protection against cardiac ischemia/reperfusion injury.

PubMed

Zhang, Mingming; Wang, Chen; Hu, Jianqiang; Lin, Jie; Zhao, Zhijing; Shen, Min; Gao, Haokao; Li, Na; Liu, Min; Zheng, Pengfei; Qiu, Cuiting; Gao, Erhe; Wang, Haichang; Sun, Dongdong

2015-09-01

Oncostatin M (OSM) exhibits many unique biological activities by activating the Oβ receptor. However, its role in myocardial ischemia/reperfusion injury (I/R injury) in mice remains unknown. We investigated whether Notch3/Akt signaling is involved in the regulation of OSM-induced protection against cardiac I/R injury. The effects of OSM were assessed in mice that underwent myocardial I/R injury by OSM treatment or by genetic deficiency of the OSM receptor Oβ. We investigated its effects on cardiomyocyte apoptosis and mitochondrial biogenesis and whether Notch3/Akt signaling was involved in the regulation of OSM-induced protection against cardiac I/R injury. The mice underwent 30 min of ischemia followed by 3 h of reperfusion and were randomized to be treated with Notch3 siRNA (siNotch3) or lentivirus carrying Notch3 cDNA (Notch3) 72 h before coronary artery ligation. Myocardial infarct size, cardiac function, cardiomyocyte apoptosis and mitochondria morphology in mice that underwent cardiac I/R injury were compared between groups. OSM alleviated cardiac I/R injury by inhibiting cardiomyocyte apoptosis through promotion of Notch3 production, thus activating the PI3K/Akt pathway. OSM enhanced mitochondrial biogenesis and mitochondrial function in mice subjected to cardiac I/R injury. In contrast, OSM receptor Oβ knock out exacerbated cardiac I/R injury, decreased Notch3 production, enhanced cardiomyocyte apoptosis, and impaired mitochondrial biogenesis in cardiac I/R injured mice. The mechanism of OSM on cardiac I/R injury is partly mediated by the Notch3/Akt pathway. These results suggest a novel role of Notch3/Akt signaling that contributes to OSM-induced protection against cardiac I/R injury.

Creatine Enhances Mitochondrial-Mediated Oligodendrocyte Survival After Demyelinating Injury.

PubMed

Chamberlain, Kelly A; Chapey, Kristen S; Nanescu, Sonia E; Huang, Jeffrey K

2017-02-08

Chronic oligodendrocyte loss, which occurs in the demyelinating disorder multiple sclerosis (MS), contributes to axonal dysfunction and neurodegeneration. Current therapies are able to reduce MS severity, but do not prevent transition into the progressive phase of the disease, which is characterized by chronic neurodegeneration. Therefore, pharmacological compounds that promote oligodendrocyte survival could be beneficial for neuroprotection in MS. Here, we investigated the role of creatine, an organic acid involved in adenosine triphosphate (ATP) buffering, in oligodendrocyte function. We found that creatine increased mitochondrial ATP production directly in oligodendrocyte lineage cell cultures and exerted robust protection on oligodendrocytes by preventing cell death in both naive and lipopolysaccharide-treated mixed glia. Moreover, lysolecithin-mediated demyelination in mice deficient in the creatine-synthesizing enzyme guanidinoacetate-methyltransferase ( Gamt ) did not affect oligodendrocyte precursor cell recruitment, but resulted in exacerbated apoptosis of regenerated oligodendrocytes in central nervous system (CNS) lesions. Remarkably, creatine administration into Gamt -deficient and wild-type mice with demyelinating injury reduced oligodendrocyte apoptosis, thereby increasing oligodendrocyte density and myelin basic protein staining in CNS lesions. We found that creatine did not affect the recruitment of macrophages/microglia into lesions, suggesting that creatine affects oligodendrocyte survival independently of inflammation. Together, our results demonstrate a novel function for creatine in promoting oligodendrocyte viability during CNS remyelination. SIGNIFICANCE STATEMENT We report that creatine enhances oligodendrocyte mitochondrial function and protects against caspase-dependent oligodendrocyte apoptosis during CNS remyelination. This work has important implications for the development of therapeutic targets for diseases characterized by oligodendrocyte death, including multiple sclerosis. Copyright © 2017 Chamberlain et al.

Molecular chaperone TRAP1 regulates a metabolic switch between mitochondrial respiration and aerobic glycolysis

PubMed Central

Yoshida, Soichiro; Tsutsumi, Shinji; Muhlebach, Guillaume; Sourbier, Carole; Lee, Min-Jung; Lee, Sunmin; Vartholomaiou, Evangelia; Tatokoro, Manabu; Beebe, Kristin; Miyajima, Naoto; Mohney, Robert P.; Chen, Yang; Hasumi, Hisashi; Xu, Wanping; Fukushima, Hiroshi; Nakamura, Ken; Koga, Fumitaka; Kihara, Kazunori; Trepel, Jane; Picard, Didier; Neckers, Leonard

2013-01-01

TRAP1 (TNF receptor-associated protein), a member of the HSP90 chaperone family, is found predominantly in mitochondria. TRAP1 is broadly considered to be an anticancer molecular target. However, current inhibitors cannot distinguish between HSP90 and TRAP1, making their utility as probes of TRAP1-specific function questionable. Some cancers express less TRAP1 than do their normal tissue counterparts, suggesting that TRAP1 function in mitochondria of normal and transformed cells is more complex than previously appreciated. We have used TRAP1-null cells and transient TRAP1 silencing/overexpression to show that TRAP1 regulates a metabolic switch between oxidative phosphorylation and aerobic glycolysis in immortalized mouse fibroblasts and in human tumor cells. TRAP1-deficiency promotes an increase in mitochondrial respiration and fatty acid oxidation, and in cellular accumulation of tricarboxylic acid cycle intermediates, ATP and reactive oxygen species. At the same time, glucose metabolism is suppressed. TRAP1-deficient cells also display strikingly enhanced invasiveness. TRAP1 interaction with and regulation of mitochondrial c-Src provide a mechanistic basis for these phenotypes. Taken together with the observation that TRAP1 expression is inversely correlated with tumor grade in several cancers, these data suggest that, in some settings, this mitochondrial molecular chaperone may act as a tumor suppressor. PMID:23564345

The numbers of individual mitochondrial DNA molecules and mitochondrial DNA nucleoids in yeast are co-regulated by the general amino acid control pathway.

PubMed

MacAlpine, D M; Perlman, P S; Butow, R A

2000-02-15

Mitochondrial DNA (mtDNA) is inherited as a protein-DNA complex (the nucleoid). We show that activation of the general amino acid response pathway in rho(+) and rho(-) petite cells results in an increased number of nucleoids without an increase in mtDNA copy number. In rho(-) cells, activation of the general amino acid response pathway results in increased intramolecular recombination between tandemly repeated sequences of rho(-) mtDNA to produce small, circular oligomers that are packaged into individual nucleoids, resulting in an approximately 10-fold increase in nucleoid number. The parsing of mtDNA into nucleoids due to general amino acid control requires Ilv5p, a mitochondrial protein that also functions in branched chain amino acid biosynthesis, and one or more factors required for mtDNA recombination. Two additional proteins known to function in mtDNA recombination, Abf2p and Mgt1p, are also required for parsing mtDNA into a larger number of nucleoids, although expression of these proteins is not under general amino acid control. Increased nucleoid number leads to increased mtDNA transmission, suggesting a mechanism to enhance mtDNA inheritance under amino acid starvation conditions.

Associations between fatty acid oxidation, hepatic mitochondrial function, and plasma acylcarnitine levels in mice.

PubMed

Bjørndal, Bodil; Alterås, Eva Katrine; Lindquist, Carine; Svardal, Asbjørn; Skorve, Jon; Berge, Rolf K

2018-01-01

The 4-thia fatty acid tetradecylthiopropionic acid (TTP) is known to inhibit mitochondrial β-oxidation, and can be used as chemically induced hepatic steatosis-model in rodents, while 3-thia fatty acid tetradecylthioacetic acid (TTA) stimulates fatty acid oxidation through activation of peroxisome proliferator activated receptor alpha (PPARα). We wished to determine how these two compounds affected in vivo respiration and mitochondrial efficiency, with an additional goal to elucidate whether mitochondrial function is reflected in plasma acylcarnitine levels. C57BL/6 mice were divided in 4 groups of 10 mice and fed a control low-fat diet, low-fat diets with 0.4% ( w /w) TTP, 0.4% TTA or a combination of these two fatty acids for three weeks ( n  = 10). At sacrifice, β-oxidation and oxidative phosphorylation (OXPHOS) capacity was analysed in fresh liver samples. Hepatic mitochondria were studied using transmission electron microscopy. Lipid classes were measured in plasma, heart and liver, acylcarnitines were measured in plasma, and gene expression was measured in liver. The TTP diet resulted in hepatic lipid accumulation, plasma L-carnitine and acetylcarnitine depletion and elevated palmitoylcarnitine and non-esterified fatty acid levels. No significant lipid accumulation was observed in heart. The TTA supplement resulted in enhanced hepatic β-oxidation, accompanied by an increased level of acetylcarnitine and palmitoylcarnitine in plasma. Analysis of mitochondrial respiration showed that TTP reduced oxidative phosphorylation, while TTA increased the maximum respiratory capacity of the electron transport system. Combined treatment with TTP and TTA resulted in a profound stimulation of genes involved in the PPAR-response and L-carnitine metabolism, and partly prevented triacylglycerol accumulation in the liver concomitant with increased peroxisomal β-oxidation and depletion of plasma acetylcarnitines. Despite an increased number of mitochondria in the liver of TTA + TTP fed mice, the OXPHOS capacity was significantly reduced. This study indicates that fatty acid β-oxidation directly affects mitochondrial respiratory capacity in liver. As plasma acylcarnitines reflected the reduced mitochondrial β-oxidation in TTP-fed mice, they could be useful tools to monitor mitochondrial function. As mitochondrial dysfunction is a major determinant of metabolic disease, this supports their use as plasma markers of cardiovascular risk in humans. Results however indicate that high PPAR activation obscures the interpretation of plasma acylcarnitine levels.

Hydrogen sulfide epigenetically attenuates homocysteine-induced mitochondrial toxicity mediated through NMDA receptor in mouse brain endothelial (bEnd3) cells†

PubMed Central

Kamat, Pradip K.; Kalani, Anuradha; Tyagi, Suresh C.; Tyagi, Neetu

2014-01-01

Previously we have showed that homocysteine (Hcy) caused oxidative stress and altered mitochondrial function. Hydrogen sulphide (H2S) has potent anti-inflammatory, anti-oxidative and anti-apoptotic effects. Therefore, in the present study we examined whether H2S ameliorates Hcy-induced mitochondrial toxicity which led to endothelial dysfunction in part, by epigenetic alterations in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to 100μM Hcy treatment in the presence or absence of 30μM NaHS (donor of H2S) for 24hrs. Hcy-activate NMDA receptor and induced mitochondrial toxicity by increased levels of Ca2+, NADPH-oxidase-4 (NOX-4) expression, mitochondrial dehydrogenase activity and decreased the level of nitrate, superoxide dismutase (SOD-2) expression, mitochondria membrane potentials, ATP production. To confirm the role of epigenetic, 5′-azacitidine (an epigenetic modulator) treatment was given to the cells. Pretreatment with NaHS (30μM) attenuated the Hcy-induced increased expression of DNMT1, DNMT3a, Ca2+ and decreased expression of DNMT3b in bEND3 cells. Furthermore, NaHS treatment also enhanced mitochondrial oxidative stress (NOX4, ROS, and NO) and restored ATP that indicates its protective effects against mitochondrial toxicity. Additional, NaHS significantly alleviated Hcy-induced LC3-I/II, CSE, Atg3/7 and low p62 expression which confirm its effect on mitophagy. Likewise, NaHS also restored level of eNOS, CD31, VE-Cadherin and ET-1 and maintains endothelial function in Hcy treated cells. Molecular inhibition of NMDA receptor by using small interfering RNA showed protective effect whereas inhibition of H2S production by propargylglycine (PG) (inhibitor of enzyme CSE) showed mitotoxic effect. Taken together, results demonstrate that, administration of H2S protected the cells from HHcy-induced mitochondrial toxicity and endothelial dysfunction. PMID:25056869

Defining a Model for Mitochondrial Function in mESC Differentiation

EPA Science Inventory

Defining a Model for Mitochondrial Function in mESC DifferentiationDefining a Model for Mitochondrial Function in mESC Differentiation Differentiating embryonic stem cells (ESCs) undergo mitochondrial maturation leading to a switch from a system dependent upon glycolysis to a re...

Bioenergetic Insufficiencies Due to Metabolic Alterations Regulated by the Inhibitory Receptor PD-1 Are an Early Driver of CD8(+) T Cell Exhaustion.

PubMed

Bengsch, Bertram; Johnson, Andy L; Kurachi, Makoto; Odorizzi, Pamela M; Pauken, Kristen E; Attanasio, John; Stelekati, Erietta; McLane, Laura M; Paley, Michael A; Delgoffe, Greg M; Wherry, E John

2016-08-16

Dynamic reprogramming of metabolism is essential for T cell effector function and memory formation. However, the regulation of metabolism in exhausted CD8(+) T (Tex) cells is poorly understood. We found that during the first week of chronic lymphocytic choriomeningitis virus (LCMV) infection, before severe dysfunction develops, virus-specific CD8(+) T cells were already unable to match the bioenergetics of effector T cells generated during acute infection. Suppression of T cell bioenergetics involved restricted glucose uptake and use, despite persisting mechanistic target of rapamycin (mTOR) signaling and upregulation of many anabolic pathways. PD-1 regulated early glycolytic and mitochondrial alterations and repressed transcriptional coactivator PGC-1α. Improving bioenergetics by overexpression of PGC-1α enhanced function in developing Tex cells. Therapeutic reinvigoration by anti-PD-L1 reprogrammed metabolism in a subset of Tex cells. These data highlight a key metabolic control event early in exhaustion and suggest that manipulating glycolytic and mitochondrial metabolism might enhance checkpoint blockade outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Tauroursodeoxycholic acid increases neural stem cell pool and neuronal conversion by regulating mitochondria-cell cycle retrograde signaling

PubMed Central

Xavier, Joana M; Morgado, Ana L; Rodrigues, Cecília MP; Solá, Susana

2014-01-01

The low survival and differentiation rates of stem cells after either transplantation or neural injury have been a major concern of stem cell-based therapy. Thus, further understanding long-term survival and differentiation of stem cells may uncover new targets for discovery and development of novel therapeutic approaches. We have previously described the impact of mitochondrial apoptosis-related events in modulating neural stem cell (NSC) fate. In addition, the endogenous bile acid, tauroursodeoxycholic acid (TUDCA) was shown to be neuroprotective in several animal models of neurodegenerative disorders by acting as an anti-apoptotic and anti-oxidant molecule at the mitochondrial level. Here, we hypothesize that TUDCA might also play a role on NSC fate decision. We found that TUDCA prevents mitochondrial apoptotic events typical of early-stage mouse NSC differentiation, preserves mitochondrial integrity and function, while enhancing self-renewal potential and accelerating cell cycle exit of NSCs. Interestingly, TUDCA prevention of mitochondrial alterations interfered with NSC differentiation potential by favoring neuronal rather than astroglial conversion. Finally, inhibition of mitochondrial reactive oxygen species (mtROS) scavenger and adenosine triphosphate (ATP) synthase revealed that the effect of TUDCA is dependent on mtROS and ATP regulation levels. Collectively, these data underline the importance of mitochondrial stress control of NSC fate decision and support a new role for TUDCA in this process. PMID:25483094

XPD localizes in mitochondria and protects the mitochondrial genome from oxidative DNA damage.

PubMed

Liu, Jing; Fang, Hongbo; Chi, Zhenfen; Wu, Zan; Wei, Di; Mo, Dongliang; Niu, Kaifeng; Balajee, Adayabalam S; Hei, Tom K; Nie, Linghu; Zhao, Yongliang

2015-06-23

Xeroderma pigmentosum group D (XPD/ERCC2) encodes an ATP-dependent helicase that plays essential roles in both transcription and nucleotide excision repair of nuclear DNA, however, whether or not XPD exerts similar functions in mitochondria remains elusive. In this study, we provide the first evidence that XPD is localized in the inner membrane of mitochondria, and cells under oxidative stress showed an enhanced recruitment of XPD into mitochondrial compartment. Furthermore, mitochondrial reactive oxygen species production and levels of oxidative stress-induced mitochondrial DNA (mtDNA) common deletion were significantly elevated, whereas capacity for oxidative damage repair of mtDNA was markedly reduced in both XPD-suppressed human osteosarcoma (U2OS) cells and XPD-deficient human fibroblasts. Immunoprecipitation-mass spectrometry analysis was used to identify interacting factor(s) with XPD and TUFM, a mitochondrial Tu translation elongation factor was detected to be physically interacted with XPD. Similar to the findings in XPD-deficient cells, mitochondrial common deletion and oxidative damage repair capacity in U2OS cells were found to be significantly altered after TUFM knock-down. Our findings clearly demonstrate that XPD plays crucial role(s) in protecting mitochondrial genome stability by facilitating an efficient repair of oxidative DNA damage in mitochondria. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

The novel tumor suppressor p33ING2 enhances UVB-induced apoptosis in human melanoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, M.Y.; Ng, Kin Cheung P.; Li Gang

The roles of p33ING2 as a tumor suppressor candidate have been shown through regulation of gene transcription, induction of cell cycle arrest, and apoptosis. As p33ING2 shares 58.9% homology with p33ING1b, we hypothesized that p33ING2 shares functional similarities with p33ING1b. We previously found that p33ING1b cooperates with p53 to enhance UVB-induced apoptosis. Here, we report that overexpression of p33ING2 enhanced apoptosis in UVB-irradiated and non-irradiated melanoma MMRU cells. We demonstrate that enhancement of apoptosis by p33ING2 requires the presence of functional p53. Furthermore, we found that overexpression of p33ING2 significantly downregulated the expression of Bcl-2 after UVB irradiation, resulting inmore » an increased Bax/Bcl-2 ratio. Moreover, we found that p33ING2 promoted Bax translocation to mitochondria, altered the mitochondrial membrane potential, and induced cytochrome c release and thus the activation of caspases 9 and 3. In addition, we showed that under non-stress conditions p33ING2 upregulates Fas expression and activates caspase 8. Taken together, we demonstrate that p33ING2 cooperates with p53 to regulate apoptosis via activation of both the mitochondrial/intrinsic and death-receptor/extrinsic apoptotic pathways.« less

Palladium alpha-lipoic acid complex formulation enhances activities of Krebs cycle dehydrogenases and respiratory complexes I-IV in the heart of aged rats.

PubMed

Sudheesh, N P; Ajith, T A; Janardhanan, K K; Krishnan, C V

2009-08-01

Age-related decline in the capacity to withstand stress, such as ischemia and reperfusion, results in congestive heart failure. Though the mechanisms underlying cardiac decay are not clear, age dependent somatic damages to mitochondrial DNA (mtDNA), loss of mitochondrial function, and a resultant increase in oxidative stress in heart muscle cells may be responsible for the increased risk for cardiovascular diseases. The effect of a safe nutritional supplement, POLY-MVA, containing the active ingredient palladium alpha-lipoic acid complex, was evaluated on the activities of the Krebs cycle enzymes such as isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase as well as mitochondrial complexes I, II, III, and IV in heart mitochondria of aged male albino rats of Wistar strain. Administration of 0.05 ml/kg of POLY-MVA (which is equivalent to 0.38 mg complexed alpha-lipoic acid/kg, p.o), once daily for 30 days, was significantly (p<0.05) effective to enhance the Krebs cycle dehydrogenases, and mitochondrial electron transport chain complexes. The unique electronic and redox properties of palladium alpha-lipoic acid complex appear to be a key to this physiological effectiveness. The results strongly suggest that this formulation might be effective to protect the aging associated risk of cardiovascular and neurodegenerative diseases.

Manganese ions enhance mitochondrial H2O2 emission from Krebs cycle oxidoreductases by inducing permeability transition.

PubMed

Bonke, Erik; Siebels, Ilka; Zwicker, Klaus; Dröse, Stefan

2016-10-01

Manganese-induced toxicity has been linked to mitochondrial dysfunction and an increased generation of reactive oxygen species (ROS). We could recently show in mechanistic studies that Mn 2+ ions induce hydrogen peroxide (H 2 O 2 ) production from the ubiquinone binding site of mitochondrial complex II (II Q ) and generally enhance H 2 O 2 formation by accelerating the rate of superoxide dismutation. The present study with intact mitochondria reveals that manganese additionally enhances H 2 O 2 emission by inducing mitochondrial permeability transition (mPT). In mitochondria fed by NADH-generating substrates, the combination of Mn 2+ and different respiratory chain inhibitors led to a dynamically increasing H 2 O 2 emission which was sensitive to the mPT inhibitor cyclosporine A (CsA) as well as Ru-360, an inhibitor of the mitochondrial calcium uniporter (MCU). Under these conditions, flavin-containing enzymes of the mitochondrial matrix, e.g. the mitochondrial 2-oxoglutaratedehydrogenase (OGDH), were major sources of ROS. With succinate as substrate, Mn 2+ stimulated ROS production mainly at complex II, whereby the applied succinate concentration had a marked effect on the tendency for mPT. Also Ca 2+ increased the rate of H 2 O 2 emission by mPT, while no direct effect on ROS-production of complex II was observed. The present study reveals a complex scenario through which manganese affects mitochondrial H 2 O 2 emission: stimulating its production from distinct sites (e.g. site II Q ), accelerating superoxide dismutation and enhancing the emission via mPT which also leads to the loss of soluble components of the mitochondrial antioxidant systems and favors the ROS production from flavin-containing oxidoreductases of the Krebs cycle. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial Recombination and Introgression during Speciation by Hybridization.

PubMed

Leducq, Jean-Baptiste; Henault, Mathieu; Charron, Guillaume; Nielly-Thibault, Lou; Terrat, Yves; Fiumera, Heather L; Shapiro, B Jesse; Landry, Christian R

2017-08-01

Genome recombination is a major source of genotypic diversity and contributes to adaptation and speciation following interspecies hybridization. The contribution of recombination in these processes has been thought to be largely limited to the nuclear genome because organelles are mostly uniparentally inherited in animals and plants, which prevents recombination. Unicellular eukaryotes such as budding yeasts do, however, transmit mitochondria biparentally, suggesting that during hybridization, both parents could provide alleles that contribute to mitochondrial functions such as respiration and metabolism in hybrid populations or hybrid species. We examined the dynamics of mitochondrial genome transmission and evolution during speciation by hybridization in the natural budding yeast Saccharomyces paradoxus. Using population-scale mitochondrial genome sequencing in two endemic North American incipient species SpB and SpC and their hybrid species SpC*, we found that both parental species contributed to the hybrid mitochondrial genome through recombination. We support our findings by showing that mitochondrial recombination between parental types is frequent in experimental crosses that recreate the early step of this speciation event. In these artificial hybrids, we observed that mitochondrial genome recombination enhances phenotypic variation among diploid hybrids, suggesting that it could play a role in the phenotypic differentiation of hybrid species. Like the nuclear genome, the mitochondrial genome can, therefore, also play a role in hybrid speciation. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Plasma Amino Acids Stimulate Uncoupled Respiration of Muscle Subsarcolemmal Mitochondria in Lean but Not Obese Humans.

PubMed

Kras, Katon A; Hoffman, Nyssa; Roust, Lori R; Patel, Shivam H; Carroll, Chad C; Katsanos, Christos S

2017-12-01

Obesity is associated with mitochondrial dysfunction in skeletal muscle. Increasing the plasma amino acid (AA) concentrations stimulates mitochondrial adenosine triphosphate (ATP) production in lean individuals. To determine whether acute elevation in plasma AAs enhances muscle mitochondrial respiration and ATP production in subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in obese adults. Assessment of SS and IMF mitochondrial function during saline (i.e., control) and AA infusions. Eligible participants were healthy lean (body mass index, <25 kg/m2; age, 37 ± 3 years; n = 10) and obese (body mass index >30 kg/m2; age 35 ± 3 years; n = 11) subjects. Single trial of saline infusion followed by AA infusion. SS and IMF mitochondria were isolated from muscle biopsies collected at the end of the saline and AA infusions. Mitochondrial respiration and ATP production. AA infusion increased adenosine 5'-diphosphate (ADP)-stimulated respiration and ATP production rates of SS mitochondria in the lean (P < 0.05), but not obese, subjects. Furthermore, AA infusion increased the uncoupled (i.e., non-ADP-stimulated) respiration of SS mitochondria in the lean subjects only (P < 0.05). AA infusion had no effect on any of these parameters in IMF mitochondria in either lean or obese subjects (P > 0.05). Increasing the plasma AA concentrations enhances the capacity for respiration and ATP production of muscle SS, but not IMF, mitochondria in lean individuals, in parallel with increases in uncoupled respiration. However, neither of these parameters increases in muscle SS or IMF mitochondria in obese individuals. Copyright © 2017 Endocrine Society

Cholesterol contributes to dopamine-neuronal loss in MPTP mouse model of Parkinson's disease: Involvement of mitochondrial dysfunctions and oxidative stress.

PubMed

Paul, Rajib; Choudhury, Amarendranath; Kumar, Sanjeev; Giri, Anirudha; Sandhir, Rajat; Borah, Anupom

2017-01-01

Hypercholesterolemia is a known contributor to the pathogenesis of Alzheimer's disease while its role in the occurrence of Parkinson's disease (PD) is only conjecture and far from conclusive. Altered antioxidant homeostasis and mitochondrial functions are the key mechanisms in loss of dopaminergic neurons in the substantia nigra (SN) region of the midbrain in PD. Hypercholesterolemia is reported to cause oxidative stress and mitochondrial dysfunctions in the cortex and hippocampus regions of the brain in rodents. However, the impact of hypercholesterolemia on the midbrain dopaminergic neurons in animal models of PD remains elusive. We tested the hypothesis that hypercholesterolemia in MPTP model of PD would potentiate dopaminergic neuron loss in SN by disrupting mitochondrial functions and antioxidant homeostasis. It is evident from the present study that hypercholesterolemia in naïve animals caused dopamine neuronal loss in SN with subsequent reduction in striatal dopamine levels producing motor impairment. Moreover, in the MPTP model of PD, hypercholesterolemia exacerbated MPTP-induced reduction of striatal dopamine as well as dopaminergic neurons in SN with motor behavioral depreciation. Activity of mitochondrial complexes, mainly complex-I and III, was impaired severely in the nigrostriatal pathway of hypercholesterolemic animals treated with MPTP. Hypercholesterolemia caused oxidative stress in the nigrostriatal pathway with increased generation of hydroxyl radicals and enhanced activity of antioxidant enzymes, which were further aggravated in the hypercholesterolemic mice with Parkinsonism. In conclusion, our findings provide evidence of increased vulnerability of the midbrain dopaminergic neurons in PD with hypercholesterolemia.

Essential role for uncoupling protein-3 in mitochondrial adaptation to fasting but not in fatty acid oxidation or fatty acid anion export.

PubMed

Seifert, Erin L; Bézaire, Véronic; Estey, Carmen; Harper, Mary-Ellen

2008-09-12

Uncoupling protein-3 (UCP3) is a mitochondrial inner membrane protein expressed most abundantly in skeletal muscle and to a lesser extent in heart and brown adipose tissue. Evidence supports a role for UCP3 in fatty acid oxidation (FAO); however, the underlying mechanism has not been explored. In 2001 we proposed a role for UCP3 in fatty acid export, leading to higher FAO rates (Himms-Hagen, J., and Harper, M. E. (2001) Exp. Biol. Med. (Maywood) 226, 78-84). Specifically, this widely held hypothesis states that during elevated FAO rates, UCP3 exports fatty acid anions, thereby maintaining mitochondrial co-enzyme A availability; reactivation of exported fatty acid anions would ultimately enable increased FAO. Here we tested mechanistic aspects of this hypothesis as well as its functional implications, namely increased FAO rates. Using complementary mechanistic approaches in mitochondria from wild-type and Ucp3(-/-) mice, we find that UCP3 is not required for FAO regardless of substrate type or supply rate covering a 20-fold range. Fatty acid anion export and reoxidation during elevated FAO, although present in skeletal muscle mitochondria, are independent of UCP3 abundance. Interestingly, UCP3 was found to be necessary for the fasting-induced enhancement of FAO rate and capacity, possibly via mitigated mitochondrial oxidative stress. Thus, although our observations indicate that UCP3 can impact FAO rates, the mechanistic basis is not via an integral function for UCP3 in the FAO machinery. Overall our data indicate a function for UCP3 in mitochondrial adaptation to perturbed cellular energy balance and integrate previous observations that have linked UCP3 to reduced oxidative stress and FAO.

Decreased Mitochondrial Pyruvate Transport Activity in the Diabetic Heart: ROLE OF MITOCHONDRIAL PYRUVATE CARRIER 2 (MPC2) ACETYLATION.

PubMed

Vadvalkar, Shraddha S; Matsuzaki, Satoshi; Eyster, Craig A; Giorgione, Jennifer R; Bockus, Lee B; Kinter, Caroline S; Kinter, Michael; Humphries, Kenneth M

2017-03-17

Alterations in mitochondrial function contribute to diabetic cardiomyopathy. We have previously shown that heart mitochondrial proteins are hyperacetylated in OVE26 mice, a transgenic model of type 1 diabetes. However, the universality of this modification and its functional consequences are not well established. In this study, we demonstrate that Akita type 1 diabetic mice exhibit hyperacetylation. Functionally, isolated Akita heart mitochondria have significantly impaired maximal (state 3) respiration with physiological pyruvate (0.1 mm) but not with 1.0 mm pyruvate. In contrast, pyruvate dehydrogenase activity is significantly decreased regardless of the pyruvate concentration. We found that there is a 70% decrease in the rate of pyruvate transport in Akita heart mitochondria but no decrease in the mitochondrial pyruvate carriers 1 and 2 (MPC1 and MPC2). The potential role of hyperacetylation in mediating this impaired pyruvate uptake was examined. The treatment of control mitochondria with the acetylating agent acetic anhydride inhibits pyruvate uptake and pyruvate-supported respiration in a similar manner to the pyruvate transport inhibitor α-cyano-4-hydroxycinnamate. A mass spectrometry selective reactive monitoring assay was developed and used to determine that acetylation of lysines 19 and 26 of MPC2 is enhanced in Akita heart mitochondria. Expression of a double acetylation mimic of MPC2 (K19Q/K26Q) in H9c2 cells was sufficient to decrease the maximal cellular oxygen consumption rate. This study supports the conclusion that deficient pyruvate transport activity, mediated in part by acetylation of MPC2, is a contributor to metabolic inflexibility in the diabetic heart. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

High-Density Lipoprotein Maintains Skeletal Muscle Function by Modulating Cellular Respiration in Mice

PubMed Central

Lehti, Maarit; Donelan, Elizabeth; Abplanalp, William; Al-Massadi, Omar; Habegger, Kirk; Weber, Jon; Ress, Chandler; Mansfeld, Johannes; Somvanshi, Sonal; Trivedi, Chitrang; Keuper, Michaela; Ograjsek, Teja; Striese, Cynthia; Cucuruz, Sebastian; Pfluger, Paul T.; Krishna, Radhakrishna; Gordon, Scott M.; Silva, R. A. Gangani D.; Luquet, Serge; Castel, Julien; Martinez, Sarah; D'Alessio, David; Davidson, W. Sean; Hofmann, Susanna M.

2014-01-01

Background Abnormal glucose metabolism is a central feature of disorders with increased rates of cardio-vascular disease (CVD). Low levels of high density lipoprotein (HDL) are a key predictor for CVD. We used genetic mouse models with increased HDL levels (apoA-I tg) and reduced HDL levels (apoA-I ko) to investigate whether HDL modulates mitochondrial bioenergetics in skeletal muscle. Methods and Results ApoA-I ko mice exhibited fasting hyperglycemia and impaired glucose tolerance test (GTT) compared to wild type (wt) mice. Mitochondria isolated from gastrocnemius muscle of apoA-I ko mice displayed markedly blunted ATP synthesis. Endurance capacity (EC) during exercise exhaustion test was impaired in apoA-I ko mice. HDL directly enhanced glucose oxidation by increasing glycolysis and mitochondrial respiration rate (OCR) in C2C12 muscle cells. ApoA-I tg mice exhibited lower fasting glucose levels, improved GTT, increased lactate levels, reduced fat mass, associated with protection against age-induced decline of EC compared to wt mice. Circulating levels of fibroblast growth factor 21 (FGF21), a novel biomarker for mitochondrial respiratory chain deficiencies and inhibitor of white adipose lipolysis, were significantly reduced in apoA-I tg mice. Consistent with an increase in glucose utilization of skeletal muscle, genetically increased HDL and apoA-I levels in mice prevented high fat diet-induced impairment of glucose homeostasis. Conclusions In view of impaired mitochondrial function and decreased HDL levels in T2D, our findings indicate that HDL-raising therapies may preserve muscle mitochondrial function and address key aspects of T2D beyond CVD. PMID:24170386

Human, donkey and cow milk differently affects energy efficiency and inflammatory state by modulating mitochondrial function and gut microbiota.

PubMed

Trinchese, Giovanna; Cavaliere, Gina; Canani, Roberto Berni; Matamoros, Sebastien; Bergamo, Paolo; De Filippo, Chiara; Aceto, Serena; Gaita, Marcello; Cerino, Pellegrino; Negri, Rossella; Greco, Luigi; Cani, Patrice D; Mollica, Maria Pina

2015-11-01

Different nutritional components are able, by modulating mitochondrial function and gut microbiota composition, to influence body composition, metabolic homeostasis and inflammatory state. In this study, we aimed to evaluate the effects produced by the supplementation of different milks on energy balance, inflammatory state, oxidative stress and antioxidant/detoxifying enzyme activities and to investigate the role of the mitochondrial efficiency and the gut microbiota in the regulation of metabolic functions in an animal model. We compared the intake of human milk, gold standard for infant nutrition, with equicaloric supplementation of donkey milk, the best substitute for newborns due to its nutritional properties, and cow milk, the primary marketed product. The results showed a hypolipidemic effect produced by donkey and human milk intake in parallel with enhanced mitochondrial activity/proton leakage. Reduced mitochondrial energy efficiency and proinflammatory signals (tumor necrosis factor α, interleukin-1 and lipopolysaccharide levels) were associated with a significant increase of antioxidants (total thiols) and detoxifying enzyme activities (glutathione-S-transferase, NADH quinone oxidoreductase) in donkey- and human milk-treated animals. The beneficial effects were attributable, at least in part, to the activation of the nuclear factor erythroid-2-related factor-2 pathway. Moreover, the metabolic benefits induced by human and donkey milk may be related to the modulation of gut microbiota. In fact, milk treatments uniquely affected the proportions of bacterial phyla and genera, and we hypothesized that the increased concentration of fecal butyrate in human and donkey milk-treated rats was related to the improved lipid and glucose metabolism and detoxifying activities. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Centella asiatica increases hippocampal synaptic density and improves memory and executive function in aged mice.

PubMed

Gray, Nora E; Zweig, Jonathan A; Caruso, Maya; Martin, Marjoen D; Zhu, Jennifer Y; Quinn, Joseph F; Soumyanath, Amala

2018-06-19

Centella asiatica is a plant used for centuries to enhance memory. We have previously shown that a water extract of Centella asiatica (CAW) attenuates age-related spatial memory deficits in mice and improves neuronal health. Yet the effect of CAW on other cognitive domains remains unexplored as does its mechanism of improving age-related cognitive impairment. This study investigates the effects of CAW on a variety of cognitive tasks as well as on synaptic density and mitochondrial and antioxidant pathways. Twenty-month-old CB6F1 mice were treated with CAW (2 mg/ml) in their drinking water for 2 weeks prior to behavioral testing. Learning, memory, and executive function were assessed using the novel object recognition task (NORT), object location memory task (OLM), and odor discrimination reversal learning (ODRL) test. Tissue was collected for Golgi analysis of spine density as well as assessment of mitochondrial, antioxidant, and synaptic proteins. CAW improved performance in all behavioral tests suggesting effects on hippocampal and cortical dependent memory as well as on prefrontal cortex mediated executive function. There was also an increase in synaptic density in the treated animals, which was accompanied by increased expression of the antioxidant response gene NRF2 as well as the mitochondrial marker porin. These data show that CAW can increase synaptic density as well as antioxidant and mitochondrial proteins and improve multiple facets of age-related cognitive impairment. Because mitochondrial dysfunction and oxidative stress also accompany cognitive impairment in many pathological conditions this suggests a broad therapeutic utility of CAW. © 2018 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.

The Rise of Mitochondria in Medicine

PubMed Central

Picard, Martin; Wallace, Douglas C; Burelle, Yan

2016-01-01

Once considered exclusively the cell's powerhouse, mitochondria are now recognized to perform multiple essential cellular functions beyond energy production, impacting most areas of cell biology and medicine. Since the emergence of molecular biology and the discovery of pathogenic mitochondrial DNA defects in the 1980's, research advances have revealed a number of common human diseases which share an underlying pathogenesis involving mitochondrial dysfunction. Mitochondria undergo function-defining dynamic shape changes, communicate with each other, regulate gene expression within the nucleus, modulate synaptic transmission within the brain, release molecules that contribute to oncogenic transformation and trigger inflammatory responses systemically, and influence the regulation of complex physiological systems. Novel “mitopathogenic” mechanisms are thus being uncovered across a number of medical disciplines including genetics, oncology, neurology, immunology, and critical care medicine. Increasing knowledge of the bioenergetic aspects of human disease has provided new opportunities for diagnosis, therapy, prevention, and in connecting various domains of medicine. In this article, we overview specific aspects of mitochondrial biology that have contributed to – and likely will continue to enhance the progress of modern medicine. PMID:27423788

CDK1 enhances mitochondrial bioenergetics for radiation-induced DNA repair

DOE PAGES

Qin, Lili; Fan, Ming; Candas, Demet; ...

2015-12-06

Nuclear DNA repair capacity is a critical determinant of cell fate under genotoxic stress conditions. DNA repair is a well-defined energy-consuming process. However, it is unclear how DNA repair is fueled and whether mitochondrial energy production contributes to nuclear DNA repair. Here, we report a dynamic enhancement of oxygen consumption and mitochondrial ATP generation in irradiated normal cells, paralleled with increased mitochondrial relocation of the cell-cycle kinase CDK1 and nuclear DNA repair. The basal and radiation-induced mitochondrial ATP generation is reduced significantly in cells harboring CDK1 phosphorylation-deficient mutant complex I subunits. Similarly, mitochondrial ATP generation and nuclear DNA repair aremore » also compromised severely in cells harboring mitochondrially targeted, kinase-deficient CDK1. These findings demonstrate a mechanism governing the communication between mitochondria and the nucleus by which CDK1 boosts mitochondrial bioenergetics to meet the increased cellular fuel demand for DNA repair and cell survival under genotoxic stress conditions.« less

Acidosis overrides oxygen deprivation to maintain mitochondrial function and cell survival

PubMed Central

Khacho, Mireille; Tarabay, Michelle; Patten, David; Khacho, Pamela; MacLaurin, Jason G.; Guadagno, Jennifer; Bergeron, Richard; Cregan, Sean P.; Harper, Mary-Ellen; Park, David S.; Slack, Ruth S.

2014-01-01

Sustained cellular function and viability of high-energy demanding post-mitotic cells rely on the continuous supply of ATP. The utilization of mitochondrial oxidative phosphorylation for efficient ATP generation is a function of oxygen levels. As such, oxygen deprivation, in physiological or pathological settings, has profound effects on cell metabolism and survival. Here we show that mild extracellular acidosis, a physiological consequence of anaerobic metabolism, can reprogramme the mitochondrial metabolic pathway to preserve efficient ATP production regardless of oxygen levels. Acidosis initiates a rapid and reversible homeostatic programme that restructures mitochondria, by regulating mitochondrial dynamics and cristae architecture, to reconfigure mitochondrial efficiency, maintain mitochondrial function and cell survival. Preventing mitochondrial remodelling results in mitochondrial dysfunction, fragmentation and cell death. Our findings challenge the notion that oxygen availability is a key limiting factor in oxidative metabolism and brings forth the concept that mitochondrial morphology can dictate the bioenergetic status of post-mitotic cells. PMID:24686499

Ischemic preconditioning improves mitochondrial tolerance to experimental calcium overload.

PubMed

Crestanello, Juan A; Doliba, Nicolai M; Babsky, Andriy M; Doliba, Natalia M; Niibori, Koki; Whitman, Glenn J R; Osbakken, Mary D

2002-04-01

Ca(2+) overload leads to mitochondrial uncoupling, decreased ATP synthesis, and myocardial dysfunction. Pharmacologically opening of mitochondrial K(ATP) channels decreases mitochondrial Ca(2+) uptake, improving mitochondrial function during Ca(2+) overload. Ischemic preconditioning (IPC), by activating mitochondrial K(ATP) channels, may attenuate mitochondrial Ca(2+) overload and improve mitochondrial function during reperfusion. The purpose of these experiments was to study the effect of IPC (1) on mitochondrial function and (2) on mitochondrial tolerance to experimental Ca(2+) overload. Rat hearts (n = 6/group) were subjected to (a) 30 min of equilibration, 25 min of ischemia, and 30 min of reperfusion (Control) or (b) two 5-min episodes of ischemic preconditioning, 25 min of ischemia, and 30 min of reperfusion (IPC). Developed pressure (DP) was measured. Heart mitochondria were isolated at end-Equilibration (end-EQ) and at end-Reperfusion (end-RP). Mitochondrial respiratory function (state 2, oxygen consumption with substrate only; state 3, oxygen consumption stimulated by ADP; state 4, oxygen consumption after cessation of ADP phosphorylation; respiratory control index (RCI, state 3/state 4); rate of oxidative phosphorylation (ADP/Deltat), and ADP:O ratio) was measured with polarography using alpha-ketoglutarate as a substrate in the presence of different Ca(2+) concentrations (0 to 5 x 10(-7) M) to simulate Ca(2+) overload. IPC improved DP at end-RP. IPC did not improve preischemic mitochondrial respiratory function or preischemic mitochondrial response to Ca(2+) loading. IPC improved state 3, ADP/Deltat, and RCI during RP. Low Ca(2+) levels (0.5 and 1 x 10(-7) M) stimulated mitochondrial function in both groups predominantly in IPC. The Control group showed evidence of mitochondrial uncoupling at lower Ca(2+) concentrations (1 x 10(-7) M). IPC preserved state 3 at high Ca(2+) concentrations. The cardioprotective effect of IPC results, in part, from preserving mitochondrial function during reperfusion and increasing mitochondrial tolerance to Ca(2+) loading at end-RP. Activation of mitochondrial K(ATP) channels by IPC and their improvement in Ca(2+) homeostasis during RP may be the mechanism underlying this protection.

RNA Seq analysis of the role of calcium chloride stress and electron transport in mitochondria for malachite green decolorization by Aspergillus niger.

PubMed

Gomaa, Ola M; Selim, Nabila S; Wee, Josephine; Linz, John E

2017-08-01

Aspergillus niger was previously demonstrated to decolorize the commercial dye malachite green (MG) and this process was enhanced under calcium chloride (CaCl 2 ) treatment. Previous data also suggested that the decolorization process is related to mitochondrial cytochrome c. In the current work, we analyzed in depth the specific relationship between CaCl 2 treatment and MG decolorization. Gene expression analysis (RNA Seq) using Next Generation Sequencing (NGS) revealed up-regulation of 28 genes that are directly or indirectly associated with stress response functions as early as 30min of CaCl 2 treatment; these data further strengthen our previous findings that CaCl 2 treatment induces a stress response in A. niger which enhances the ability to decolorize MG. A significant increase in fluorescence observed by MitoTracker dye suggests that CaCl 2 treatment also increased mitochondrial membrane potential. Isolated mitochondrial membrane protein fractions obtained from A. niger grown under standard growth conditions decolorized MG in the presence of NADH and decolorization was enhanced in samples isolated from CaCl 2 -treated A. niger cultures. Treatment of whole mitochondrial fraction with KCN which inhibits electron transport by cytochrome c oxidase and Triton-X 100 which disrupts mitochondrial membrane integrity suggests that cyanide sensitive cytochrome c oxidase activity is a key biochemical step in MG decolorization. This suggestion was confirmed by the addition of palladium α-lipoic acid complex (PLAC) which resulted in an initial increase in decolorization. Although the role of cytochrome c and cytochrome c oxidase was confirmed at the biochemical level, changes in levels of transcripts encoding these enzymes after CaCl 2 treatment were not found to be statistically significant in RNA Seq analysis. These data suggest that the regulation of cytochrome c enzymes occur predominantly at the post-transcriptional level under CaCl 2 stress. Thus, using global transcriptomics and biochemical approaches, our study provides a molecular association between fungal mitochondrial electron transfer systems and MG decolorization. Copyright © 2017 Elsevier Inc. All rights reserved.

A novel role of the ferric reductase Cfl1 in cell wall integrity, mitochondrial function, and invasion to host cells in Candida albicans.

PubMed

Yu, Qilin; Dong, Yijie; Xu, Ning; Qian, Kefan; Chen, Yulu; Zhang, Biao; Xing, Laijun; Li, Mingchun

2014-11-01

Candida albicans is an important opportunistic pathogen, causing both superficial mucosal infections and life-threatening systemic diseases. Iron acquisition is an important factor for pathogen-host interaction and also a significant element for the pathogenicity of this organism. Ferric reductases, which convert ferric iron into ferrous iron, are important components of the high-affinity iron uptake system. Sequence analyses have identified at least 17 putative ferric reductase genes in C. albicans genome. CFL1 was the first ferric reductase identified in C. albicans. However, little is known about its roles in C. albicans physiology and pathogenicity. In this study, we found that disruption of CFL1 led to hypersensitivity to chemical and physical cell wall stresses, activation of the cell wall integrity (CWI) pathway, abnormal cell wall composition, and enhanced secretion, indicating a defect in CWI in this mutant. Moreover, this mutant showed abnormal mitochondrial activity and morphology, suggesting a link between ferric reductases and mitochondrial function. In addition, this mutant displayed decreased ability of adhesion to both the polystyrene microplates and buccal epithelial cells and invasion of host epithelial cells. These findings revealed a novel role of C. albicans Cfl1 in maintenance of CWI, mitochondrial function, and interaction between this pathogen and the host. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Pharmacologic Effects on Mitochondrial Function

ERIC Educational Resources Information Center

Cohen, Bruce H.

2010-01-01

The vast majority of energy necessary for cellular function is produced in mitochondria. Free-radical production and apoptosis are other critical mitochondrial functions. The complex structure, electrochemical properties of the inner mitochondrial membrane (IMM), and genetic control from both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) are…

Peroxiredoxin 3 Is a Redox-Dependent Target of Thiostrepton in Malignant Mesothelioma Cells

PubMed Central

Newick, Kheng; Cunniff, Brian; Preston, Kelsey; Held, Paul; Arbiser, Jack; Pass, Harvey; Mossman, Brooke; Shukla, Arti; Heintz, Nicholas

2012-01-01

Thiostrepton (TS) is a thiazole antibiotic that inhibits expression of FOXM1, an oncogenic transcription factor required for cell cycle progression and resistance to oncogene-induced oxidative stress. The mechanism of action of TS is unclear and strategies that enhance TS activity will improve its therapeutic potential. Analysis of human tumor specimens showed FOXM1 is broadly expressed in malignant mesothelioma (MM), an intractable tumor associated with asbestos exposure. The mechanism of action of TS was investigated in a cell culture model of human MM. As for other tumor cell types, TS inhibited expression of FOXM1 in MM cells in a dose-dependent manner. Suppression of FOXM1 expression and coincidental activation of ERK1/2 by TS were abrogated by pre-incubation of cells with the antioxidant N-acetyl-L-cysteine (NAC), indicating its mechanism of action in MM cells is redox-dependent. Examination of the mitochondrial thioredoxin reductase 2 (TR2)-thioredoxin 2 (TRX2)-peroxiredoxin 3 (PRX3) antioxidant network revealed that TS modifies the electrophoretic mobility of PRX3. Incubation of recombinant human PRX3 with TS in vitro also resulted in PRX3 with altered electrophoretic mobility. The cellular and recombinant species of modified PRX3 were resistant to dithiothreitol and SDS and suppressed by NAC, indicating that TS covalently adducts cysteine residues in PRX3. Reduction of endogenous mitochondrial TRX2 levels by the cationic triphenylmethane gentian violet (GV) promoted modification of PRX3 by TS and significantly enhanced its cytotoxic activity. Our results indicate TS covalently adducts PRX3, thereby disabling a major mitochondrial antioxidant network that counters chronic mitochondrial oxidative stress. Redox-active compounds like GV that modify the TR2/TRX2 network may significantly enhance the efficacy of TS, thereby providing a combinatorial approach for exploiting redox-dependent perturbations in mitochondrial function as a therapeutic approach in mesothelioma. PMID:22761781

Metabolic reprogramming during neuronal differentiation.

PubMed

Agostini, M; Romeo, F; Inoue, S; Niklison-Chirou, M V; Elia, A J; Dinsdale, D; Morone, N; Knight, R A; Mak, T W; Melino, G

2016-09-01

Newly generated neurons pass through a series of well-defined developmental stages, which allow them to integrate into existing neuronal circuits. After exit from the cell cycle, postmitotic neurons undergo neuronal migration, axonal elongation, axon pruning, dendrite morphogenesis and synaptic maturation and plasticity. Lack of a global metabolic analysis during early cortical neuronal development led us to explore the role of cellular metabolism and mitochondrial biology during ex vivo differentiation of primary cortical neurons. Unexpectedly, we observed a huge increase in mitochondrial biogenesis. Changes in mitochondrial mass, morphology and function were correlated with the upregulation of the master regulators of mitochondrial biogenesis, TFAM and PGC-1α. Concomitant with mitochondrial biogenesis, we observed an increase in glucose metabolism during neuronal differentiation, which was linked to an increase in glucose uptake and enhanced GLUT3 mRNA expression and platelet isoform of phosphofructokinase 1 (PFKp) protein expression. In addition, glutamate-glutamine metabolism was also increased during the differentiation of cortical neurons. We identified PI3K-Akt-mTOR signalling as a critical regulator role of energy metabolism in neurons. Selective pharmacological inhibition of these metabolic pathways indicate existence of metabolic checkpoint that need to be satisfied in order to allow neuronal differentiation.

Metabolic reprogramming during neuronal differentiation

PubMed Central

Agostini, M; Romeo, F; Inoue, S; Niklison-Chirou, M V; Elia, A J; Dinsdale, D; Morone, N; Knight, R A; Mak, T W; Melino, G

2016-01-01

Newly generated neurons pass through a series of well-defined developmental stages, which allow them to integrate into existing neuronal circuits. After exit from the cell cycle, postmitotic neurons undergo neuronal migration, axonal elongation, axon pruning, dendrite morphogenesis and synaptic maturation and plasticity. Lack of a global metabolic analysis during early cortical neuronal development led us to explore the role of cellular metabolism and mitochondrial biology during ex vivo differentiation of primary cortical neurons. Unexpectedly, we observed a huge increase in mitochondrial biogenesis. Changes in mitochondrial mass, morphology and function were correlated with the upregulation of the master regulators of mitochondrial biogenesis, TFAM and PGC-1α. Concomitant with mitochondrial biogenesis, we observed an increase in glucose metabolism during neuronal differentiation, which was linked to an increase in glucose uptake and enhanced GLUT3 mRNA expression and platelet isoform of phosphofructokinase 1 (PFKp) protein expression. In addition, glutamate–glutamine metabolism was also increased during the differentiation of cortical neurons. We identified PI3K–Akt–mTOR signalling as a critical regulator role of energy metabolism in neurons. Selective pharmacological inhibition of these metabolic pathways indicate existence of metabolic checkpoint that need to be satisfied in order to allow neuronal differentiation. PMID:27058317

Endothelial AMPK Activation Induces Mitochondrial Biogenesis and Stress Adaptation via eNOS-Dependent mTORC1 Signaling

PubMed Central

Li, Chunying; Reif, Michaella M; Craige, Siobhan; Kant, Shashi; Keaney, John F.

2016-01-01

Metabolic stress sensors like AMP-activated protein kinase (AMPK) are known to confer stress adaptation and promote longevity in lower organisms. This study demonstrates that activating the metabolic stress sensor AMP-activated protein kinase (AMPK) in endothelial cells helps maintain normal cellular function by promoting mitochondrial biogenesis and stress adaptation. To better define the mechanisms whereby AMPK promotes endothelial stress resistance, we used 5-aminoimidazole-4-carboxamide riboside (AICAR) to chronically activate AMPK and observed stimulation of mitochondrial biogenesis in wild type mouse endothelium, but not in endothelium from endothelial nitric oxide synthase knockout (eNOS-null) mice. Interestingly, AICAR-enhanced mitochondrial biogenesis was blocked by pretreatment with the mammalian target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin. Further, AICAR stimulated mTORC1 as determined by phosphorylation of its known downstream effectors in wild type, but not eNOS-null, endothelial cells. Together these data indicate that eNOS is needed to couple AMPK activation to mTORC1 and thus promote mitochondrial biogenesis and stress adaptation in the endothelium. These data suggest a novel mechanism for mTORC1 activation that is significant for investigations in vascular dysfunction. PMID:26989010

TSA protects H9c2 cells against thapsigargin-induced apoptosis related to endoplasmic reticulum stress-mediated mitochondrial injury.

PubMed

Li, Zhiping; Liu, Yan; Dai, Xinlun; Zhou, Qiangqiang; Liu, Xueli; Li, Zeyu; Chen, Xia

2017-05-01

Endoplasmic reticulum stress (ERS) activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. Recently, TSA has shown protective effects on ERS and its mechanisms related to ER pathway has been previously characterized. However, whether TSA exerts its protective role via metabolic events remain largely undefined. Objectives : To explore the possible involvement of the metabolic changes during ERS and to better understand how TSA influence mitochondrial function to facilitate cellular adaptation. Results : TSA is an inhibitor of histone deacetylase which could significantly inhibit H9c2 cell apoptosis induced by Thapsigargin (TG). It also intervene the decrease of mitochondrial membrane potential. By immunofluorescence staining, we have shown that GRP78 was concentrated in the perinuclear region and co-localized with ER. However, treatments with TG and TSA could let it overlap with the mitochondrial marker MitoTracker. Cellular fractionation also confirmed the location of GRP78 in mitochondrion. TSA decreases ERS-induced cell apoptosis and mitochondrial injury may related to enhance the location of GRP78 in mitochondrion.

Effects of local irradiation combined with sunitinib on early remodeling, mitochondria, and oxidative stress in the rat heart

PubMed Central

Sridharan, Vijayalakshmi; Thomas, Chanice J.; Cao, Maohua; Melnyk, Stepan B.; Pavliv, Oleksandra; Joseph, Jacob; Singh, Sharda P.; Sharma, Sunil; Moros, Eduardo G.; Boerma, Marjan

2016-01-01

Background and Purpose Thoracic (chemo)radiation therapy is increasingly administered with tyrosine kinase inhibitors (TKI). While TKI have adverse effects on the heart, it is unknown whether combination with other cancer therapies causes enhanced toxicity. We used an animal model to investigate whether radiation and sunitinib interact in their effects on the heart. Material and Methods Male Sprague-Dawley rats received local heart irradiation (9 Gy per day, 5 days). Oral sunitinib (8 or 15 mg/kg bodyweight per day) started on day 1 of irradiation and continued for 2 weeks. Cardiac function was examined with echocardiography. Cardiac remodeling, cell death, left ventricular (LV) oxidative stress markers, mitochondrial morphology and membrane permeability transition pore (mPTP) opening were assessed. Results Cardiac diameter, stroke volume, and LV volume, mass and anterior wall thickness increased in time, but only in the vehicle group. Sunitinib reduced LV inner diameter and volume in systole, which were counteracted by radiation. Sunitinib and radiation showed enhanced effects on mitochondrial morphology and mPTP opening, but not on cardiac troponin I, mast cell numbers or markers of oxidative stress. Conclusions This study found no early enhanced effects of radiation and sunitinib on cardiac function or structure. Long-term effects remain to be determined. PMID:27072940

Atrial natriuretic peptide regulates lipid mobilization and oxygen consumption in human adipocytes by activating AMPK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Souza, Sandra C.; Chau, Mary D.L.; Yang, Qing

2011-07-08

Highlights: {yields} Treatment of differentiated human adipocytes with atrial natriuretic peptide (ANP) increased lipolysis and oxygen consumption by activating AMP-activated protein kinase (AMPK). {yields} ANP stimulated lipid mobilization by selective activation of the alpha2 subunit of AMPK and increased energy utilization through activation of both the alpha1 and alpha2 subunits of AMPK. {yields} ANP enhanced adipocyte mitochondrial oxidative capacity as evidenced by induction of oxidative mitochondrial genes and increase in oxygen consumption. {yields} Exposure of human adipocytes to fatty acids and (TNF{alpha}) induced insulin resistance and decreased expression of mitochondrial genes which was restored to normal by ANP. -- Abstract:more » Atrial natriuretic peptide (ANP) has been shown to regulate lipid and carbohydrate metabolism providing a possible link between cardiovascular function and metabolism by mediating the switch from carbohydrate to lipid mobilization and oxidation. ANP exerts a potent lipolytic effect via cGMP-dependent protein kinase (cGK)-I mediated-stimulation of AMP-activated protein kinase (AMPK). Activation of the ANP/cGK signaling cascade also promotes muscle mitochondrial biogenesis and fat oxidation. Here we demonstrate that ANP regulates lipid metabolism and oxygen utilization in differentiated human adipocytes by activating the alpha2 subunit of AMPK. ANP treatment increased lipolysis by seven fold and oxygen consumption by two fold, both of which were attenuated by inhibition of AMPK activity. ANP-induced lipolysis was shown to be mediated by the alpha2 subunit of AMPK as introduction of dominant-negative alpha2 subunit of AMPK attenuated ANP effects on lipolysis. ANP-induced activation of AMPK enhanced mitochondrial oxidative capacity as evidenced by a two fold increase in oxygen consumption and induction of mitochondrial genes, including carnitine palmitoyltransferase 1A (CPT1a) by 1.4-fold, cytochrome C (CytC) by 1.3-fold, and peroxisome proliferator-activated receptor-{gamma} coactivator-1{alpha} (PGC-1{alpha}) by 1.4-fold. Treatment of human adipocytes with fatty acids and tumor necrosis factor {alpha} (TNF{alpha}) induced insulin resistance and down-regulation of mitochondrial genes, which was restored by ANP treatment. These results show that ANP regulates lipid catabolism and enhances energy dissipation through AMPK activation in human adipocytes.« less

Effect of moderate exercise on peritoneal neutrophils from juvenile rats.

PubMed

Braz, Glauber Ruda; Ferreira, Diorginis Soares; Pedroza, Anderson Apolonio; da Silva, Aline Isabel; Sousa, Shirley Maria; Pithon-Curi, Tania Cristina; Lagranha, Claudia

2015-09-01

Previous studies showed that moderate exercise in adult rats enhances neutrophil function, although no studies were performed in juvenile rats. We evaluated the effects of moderate exercise on the neutrophil function in juvenile rats. Viability and neutrophils function were evaluated. Moderate exercise did not impair the viability and mitochondrial transmembrane potential of neutrophils, whereas there was greater reactive oxygen species production (164%; p < 0.001) and phagocytic capacity (29%; p < 0.05). Our results suggest that moderate exercise in juvenile rats improves neutrophil function, similar to adults.

A Creatine-Driven Substrate Cycle Enhances Energy Expenditure and Thermogenesis in Beige Fat

PubMed Central

Kazak, Lawrence; Chouchani, Edward T.; Jedrychowski, Mark P.; Erickson, Brian K.; Shinoda, Kosaku; Cohen, Paul; Vetrivelan, Ramalingam; Lu, Gina Z.; Laznik-Bogoslavski, Dina; Hasenfuss, Sebastian C.; Kajimura, Shingo; Gygi, Steve P.; Spiegelman, Bruce M.

2015-01-01

SUMMARY Thermogenic brown and beige adipose tissues dissipate chemical energy as heat, and their thermogenic activities can combat obesity and diabetes. Herein the functional adaptations to cold of brown and beige adipose depots are examined using quantitative mitochondrial proteomics. We identify arginine/creatine metabolism as a beige adipose signature and demonstrate that creatine enhances respiration in beige fat mitochondria when ADP is limiting. In murine beige fat, cold exposure stimulates mitochondrial Creatine Kinase activity and induces coordinated expression of genes associated with creatine metabolism. Pharmacological reduction of creatine levels decreases whole body energy expenditure after administration of a β3-agonist and reduces the adipose metabolic rate. Genes of creatine metabolism are compensatorily induced when UCP1-dependent thermogenesis is ablated, and creatine reduction in Ucp1-deficient mice reduces core body temperature. These findings link a futile cycle of creatine metabolism to adipose tissue energy expenditure and thermal homeostasis. PMID:26496606

Altered mitochondrial acetylation profiles in a kainic acid model of temporal lobe epilepsy.

PubMed

Gano, Lindsey B; Liang, Li-Ping; Ryan, Kristen; Michel, Cole R; Gomez, Joe; Vassilopoulos, Athanassios; Reisdorph, Nichole; Fritz, Kristofer S; Patel, Manisha

2018-08-01

Impaired bioenergetics and oxidative damage in the mitochondria are implicated in the etiology of temporal lobe epilepsy, and hyperacetylation of mitochondrial proteins has recently emerged as a critical negative regulator of mitochondrial functions. However, the roles of mitochondrial acetylation and activity of the primary mitochondrial deacetylase, SIRT3, have not been explored in acquired epilepsy. We investigated changes in mitochondrial acetylation and SIRT3 activity in the development of chronic epilepsy in the kainic acid rat model of TLE. Hippocampal measurements were made at 48 h, 1 week and 12 weeks corresponding to the acute, latent and chronic stages of epileptogenesis. Assessment of hippocampal bioenergetics demonstrated a ≥ 27% decrease in the ATP/ADP ratio at all phases of epileptogenesis (p < 0.05), whereas cellular NAD+ levels were decreased by ≥ 41% in the acute and latent time points (p < 0.05), but not in chronically epileptic rats. In spontaneously epileptic rats, we found decreased protein expression of SIRT3 and a 60% increase in global mitochondrial acetylation, as well as enhanced acetylation of the known SIRT3 substrates MnSOD, Ndufa9 of Complex I and IDH2 (all p < 0.05), suggesting SIRT3 dysfunction in chronic epilepsy. Mass spectrometry-based acetylomics investigation of hippocampal mitochondria demonstrated a 79% increase in unique acetylated proteins from rats in the chronic phase vs. controls. Pathway analysis identified numerous mitochondrial bioenergetic pathways affected by mitochondrial acetylation. These results suggest SIRT3 dysfunction and aberrant protein acetylation may contribute to mitochondrial dysfunction in chronic epilepsy. Copyright © 2018 Elsevier Inc. All rights reserved.

Rat liver mitochondrial damage under acute or chronic carbon tetrachloride-induced intoxication: Protection by melatonin and cranberry flavonoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheshchevik, V.T.; Department of Biochemistry, Yanka Kupala Grodno State University, Len. Kom. Blvd. - 50, 230017 Grodno; Lapshina, E.A.

In current societies, the risk of toxic liver damage has markedly increased. The aim of the present work was to carry out further research into the mechanism(s) of liver mitochondrial damage induced by acute (0.8 g/kg body weight, single injection) or chronic (1.6 g/ kg body weight, 30 days, biweekly injections) carbon tetrachloride – induced intoxication and to evaluate the hepatoprotective potential of the antioxidant, melatonin, as well as succinate and cranberry flavonoids in rats. Acute intoxication resulted in considerable impairment of mitochondrial respiratory parameters in the liver. The activity of mitochondrial succinate dehydrogenase (complex II) decreased (by 25%, pmore » < 0.05). Short-term melatonin treatment (10 mg/kg, three times) of rats did not reduce the degree of toxic mitochondrial dysfunction but decreased the enhanced NO production. After 30-day chronic intoxication, no significant change in the respiratory activity of liver mitochondria was observed, despite marked changes in the redox-balance of mitochondria. The activities of the mitochondrial enzymes, succinate dehydrogenase and glutathione peroxidase, as well as that of cytoplasmic catalase in liver cells were inhibited significantly. Mitochondria isolated from the livers of the rats chronically treated with CCl{sub 4} displayed obvious irreversible impairments. Long-term melatonin administration (10 mg/kg, 30 days, daily) to chronically intoxicated rats diminished the toxic effects of CCl{sub 4}, reducing elevated plasma activities of alanine aminotransferase and aspartate aminotransferase and bilirubin concentration, prevented accumulation of membrane lipid peroxidation products in rat liver and resulted in apparent preservation of the mitochondrial ultrastructure. The treatment of the animals by the complex of melatonin (10 mg/kg) plus succinate (50 mg/kg) plus cranberry flavonoids (7 mg/kg) was even more effective in prevention of toxic liver injury and liver mitochondria damage. Highlights: ► After 30-day chronic CCl{sub 4} intoxication mitochondria displayed considerable changes. ► The functional parameters of mitochondria were similar to the control values. ► Melatonin + succinate + flavonoids prevented mitochondrial ultrastructure damage. ► The above complex enhanced regenerative processes in the liver.« less

A role for Mfb1p in region-specific anchorage of high-functioning mitochondria and lifespan in Saccharomyces cerevisiae

PubMed Central

Pernice, Wolfgang M.; Vevea, Jason D.; Pon, Liza A.

2016-01-01

Previous studies indicate that replicative lifespan in daughter cells of Sacchraromyces cerevisiae depends on the preferential inheritance of young, high-functioning mitochondria. We report here that mitochondria are functionally segregated even within single mother cells in S. cerevisiae. A high-functioning population of mitochondria accumulates at the tip of the mother cell distal to the bud. We find that the mitochondrial F-box protein (Mfb1p) localizes to mitochondria in the mother tip and is required for mitochondrial anchorage at that site, independent of the previously identified anchorage protein Num1p. Deletion of MFB1 results in loss of the mother-tip-localized mitochondrial population, defects in mitochondrial function and premature replicative ageing. Inhibiting mitochondrial inheritance to buds, by deletion of MMR1, in mfb1Δ cells restores mitochondrial distribution, promotes mitochondrial function and extends replicative lifespan. Our results identify a mechanism that retains a reservoir of high-functioning mitochondria in mother cells and thereby preserves maternal reproductive capacity. PMID:26839174

The generation of oxidative stress-induced rearrangements in Saccharomyces cerevisiae mtDNA is dependent on the Nuc1 (EndoG/ExoG) nuclease and is enhanced by inactivation of the MRX complex.

PubMed

Dzierzbicki, Piotr; Kaniak-Golik, Aneta; Malc, Ewa; Mieczkowski, Piotr; Ciesla, Zygmunt

2012-12-01

Oxidative stress is known to enhance the frequency of two major types of alterations in the mitochondrial genome of Saccharomyces cerevisiae: point mutations and large deletions resulting in the generation of respiration-deficient petite rhō mutants. We investigated the effect of antimycin A, a well-known agent inducing oxidative stress, on the stability of mtDNA. We show that antimycin enhances exclusively the generation of respiration-deficient petite mutants and this is accompanied by a significant increase in the level of reactive oxygen species (ROS) and in a marked drop of cellular ATP. Whole mitochondrial genome sequencing revealed that mtDNAs of antimycin-induced petite mutants are deleted for most of the wild-type sequence and usually contain one of the active origins of mtDNA replication: ori1, ori2 ori3 or ori5. We show that the frequency of antimycin-induced rhō mutants is significantly elevated in mutants deleted either for the RAD50 or XRS2 gene, both encoding the components of the MRX complex, which is known to be involved in the repair of double strand breaks (DSBs) in DNA. Furthermore, enhanced frequency of rhō mutants in cultures of antimycin-treated cells lacking Rad50 was further increased by the simultaneous absence of the Ogg1 glycosylase, an important enzyme functioning in mtBER. We demonstrate also that rad50Δ and xrs2Δ deletion mutants display a considerable reduction in the frequency of allelic mitochondrial recombination, suggesting that it is the deficiency in homologous recombination which is responsible for enhanced rearrangements of mtDNA in antimycin-treated cells of these mutants. Finally, we show that the generation of large-scale mtDNA deletions induced by antimycin is markedly decreased in a nuc1Δ mutant lacking the activity of the Nuc1 nuclease, an ortholog of the mammalian mitochondrial nucleases EndoG and ExoG. This result indicates that the nuclease plays an important role in processing of oxidative stress-induced lesions in the mitochondrial genome. Copyright © 2012 Elsevier B.V. All rights reserved.

Contributions of Bcl-xL to acute and long term changes in bioenergetics during neuronal plasticity.

PubMed

Jonas, Elizabeth A

2014-08-01

Mitochondria manufacture and release metabolites and manage calcium during neuronal activity and synaptic transmission, but whether long term alterations in mitochondrial function contribute to the neuronal plasticity underlying changes in organism behavior patterns is still poorly understood. Although normal neuronal plasticity may determine learning, in contrast a persistent decline in synaptic strength or neuronal excitability may portend neurite retraction and eventual somatic death. Anti-death proteins such as Bcl-xL not only provide neuroprotection at the neuronal soma during cell death stimuli, but also appear to enhance neurotransmitter release and synaptic growth and development. It is proposed that Bcl-xL performs these functions through its ability to regulate mitochondrial release of bioenergetic metabolites and calcium, and through its ability to rapidly alter mitochondrial positioning and morphology. Bcl-xL also interacts with proteins that directly alter synaptic vesicle recycling. Bcl-xL translocates acutely to sub-cellular membranes during neuronal activity to achieve changes in synaptic efficacy. After stressful stimuli, pro-apoptotic cleaved delta N Bcl-xL (ΔN Bcl-xL) induces mitochondrial ion channel activity leading to synaptic depression and this is regulated by caspase activation. During physiological states of decreased synaptic stimulation, loss of mitochondrial Bcl-xL and low level caspase activation occur prior to the onset of long term decline in synaptic efficacy. The degree to which Bcl-xL changes mitochondrial membrane permeability may control the direction of change in synaptic strength. The small molecule Bcl-xL inhibitor ABT-737 has been useful in defining the role of Bcl-xL in synaptic processes. Bcl-xL is crucial to the normal health of neurons and synapses and its malfunction may contribute to neurodegenerative disease. Copyright © 2013. Published by Elsevier B.V.

Resveratrol Improves the Mitochondrial Function and Fertilization Outcome of Bovine Oocytes

PubMed Central

TAKEO, Shun; SATO, Daichi; KIMURA, Koji; MONJI, Yasunori; KUWAYAMA, Takehito; KAWAHARA-MIKI, Ryoka; IWATA, Hisataka

2013-01-01

The aim of the present study was to address the effect of resveratrol-mediated upregulation of sirtuin 1 (SIRT1) during oocyte maturation on mitochondrial function, the developmental ability of oocytes and on mechanisms responsible for blockage of polyspermic fertilization. Oocytes collected from slaughterhouse-derived ovaries were cultured in TCM-199 medium supplemented with 10% FCS and 0 or 20 µM resveratrol (Res). We examined the effect of Res on SIRT1 expression in in vitro-matured oocytes (Exp 1); fertilization and developmental ability (Exp 2); mitochondrial DNA copy number (Mt number), ATP content and mitochondrial membrane potential in matured oocytes (Exp 3); and the time required for proteinase to dissolve the zona pellucida following in vitro fertilization (as a marker of zona pellucida hardening), as well as on the distribution of cortical granules before and after fertilization (Exp 4). In Exp 1, the 20 µM Res treatment upregulated protein expression of SIRT1 in oocytes. In Exp 2, Res treatment improved the ratio of normal fertilization and the total cell number of blastocysts. In Exp 3, Res treatment significantly increased the ATP content in matured oocytes. Additionally, Res increased the overall Mt number and mitochondrial membrane potential, but the effect was donor-dependent. In Exp 4, Res-induced zona hardening improved the distribution and exocytosis of cortical granules after in vitro fertilization. In conclusion, Res improved the quality of oocytes by improving mitochondrial quantity and quality. In addition, Res added to the maturation medium enhanced SIRT1 protein expression in oocytes and improved fertilization via reinforcement of the mechanisms responsible for blockage of polyspermic fertilization. PMID:24390595

Fasting and refeeding differentially regulate NLRP3 inflammasome activation in human subjects

PubMed Central

Traba, Javier; Kwarteng-Siaw, Miriam; Okoli, Tracy C.; Li, Jessica; Huffstutler, Rebecca D.; Bray, Amanda; Waclawiw, Myron A.; Han, Kim; Pelletier, Martin; Sauve, Anthony A.; Siegel, Richard M.; Sack, Michael N.

2015-01-01

BACKGROUND. Activation of the NLRP3 inflammasome is associated with metabolic dysfunction, and intermittent fasting has been shown to improve clinical presentation of NLRP3 inflammasome–linked diseases. As mitochondrial perturbations, which function as a damage-associated molecular pattern, exacerbate NLRP3 inflammasome activation, we investigated whether fasting blunts inflammasome activation via sirtuin-mediated augmentation of mitochondrial integrity. METHODS. We performed a clinical study of 19 healthy volunteers. Each subject underwent a 24-hour fast and then was fed a fixed-calorie meal. Blood was drawn during the fasted and fed states and analyzed for NRLP3 inflammasome activation. We enrolled an additional group of 8 healthy volunteers to assess the effects of the sirtuin activator, nicotinamide riboside, on NLRP3 inflammasome activation. RESULTS. In the fasting/refeeding study, individuals showed less NLRP3 inflammasome activation in the fasted state compared with that in refed conditions. In a human macrophage line, depletion of the mitochondrial-enriched sirtuin deacetylase SIRT3 increased NLRP3 inflammasome activation in association with excessive mitochondrial ROS production. Furthermore, genetic and pharmacologic SIRT3 activation blunted NLRP3 activity in parallel with enhanced mitochondrial function in cultured cells and in leukocytes extracted from healthy volunteers and from refed individuals but not in those collected during fasting. CONCLUSIONS. Together, our data indicate that nutrient levels regulate the NLRP3 inflammasome, in part through SIRT3-mediated mitochondrial homeostatic control. Moreover, these results suggest that deacetylase-dependent inflammasome attenuation may be amenable to targeting in human disease. TRIAL REGISTRATION. ClinicalTrials.gov NCT02122575 and NCT00442195. FUNDING. Division of Intramural Research, NHLBI of the NIH. PMID:26529255

Mitochondrial dysfunction due to oxidative mitochondrial DNA damage is reduced through cooperative actions of diverse proteins.

PubMed

O'Rourke, Thomas W; Doudican, Nicole A; Mackereth, Melinda D; Doetsch, Paul W; Shadel, Gerald S

2002-06-01

The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2 Delta strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues.

SIRT3 activator Honokiol attenuates β-Amyloid by modulating amyloidogenic pathway

PubMed Central

Lynd, Tyler; Briggs, Gwyneth; Adamek, Danielle; Jones, Ellery; Heiner, Jake; Majrashi, Mohammed; Moore, Timothy; Amin, Rajesh; Suppiramaniam, Vishnu

2018-01-01

Honokiol (poly-phenolic lignan from Magnolia grandiflora) is a Sirtuin-3 (SIRT3) activator which exhibit antioxidant activity and augment mitochondrial functions in several experimental models. Modern evidence suggests the critical role of SIRT3 in the progression of several metabolic and neurodegenerative diseases. Amyloid beta (Aβ), the precursor to extracellular senile plaques, accumulates in the brains of patients with Alzheimer’s disease (AD) and is related to the development of cognitive impairment and neuronal cell death. Aβ is generated from amyloid-β precursor protein (APP) through sequential cleavages, first by β-secretase and then by γ-secretase. Drugs modulating this pathway are believed to be one of the most promising strategies for AD treatment. In the present study, we found that Honokiol significantly enhanced SIRT3 expression, reduced reactive oxygen species generation and lipid peroxidation, enhanced antioxidant activities, and mitochondrial function thereby reducing Aβ and sAPPβ levels in Chinese Hamster Ovarian (CHO) cells (carrying the amyloid precursor protein-APP and Presenilin PS1 mutation). Mechanistic studies revealed that Honokiol affects neither protein levels of APP nor α-secretase activity. In contrast, Honokiol increased the expression of AMPK, CREB, and PGC-1α, thereby inhibiting β-secretase activity leading to reduced Aβ levels. These results suggest that Honokiol is an activator of SIRT3 capable of improving antioxidant activity, mitochondrial energy regulation, while decreasing Aβ, thereby indicating it to be a lead compound for AD drug development. PMID:29324783

Resveratrol Co-Treatment Attenuates the Effects of HIV Protease Inhibitors on Rat Body Weight and Enhances Cardiac Mitochondrial Respiration

PubMed Central

Symington, Burger; Mapanga, Rudo F.; Norton, Gavin R.

2017-01-01

Since the early 1990s human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) emerged as a global health pandemic, with sub-Saharan Africa the hardest hit. While the successful roll-out of antiretroviral (ARV) therapy provided significant relief to HIV-positive individuals, such treatment can also elicit damaging side-effects. Here especially HIV protease inhibitors (PIs) are implicated in the onset of cardio-metabolic complications such as type-2 diabetes and coronary heart disease. As there is a paucity of data regarding suitable co-treatments within this context, this preclinical study investigated whether resveratrol (RSV), aspirin (ASP) or vitamin C (VitC) co-treatment is able to blunt side-effects in a rat model of chronic PI exposure (Lopinavir/Ritonavir treatment for 4 months). Body weights and weight gain, blood metabolite levels (total cholesterol, HDL, LDL, triglycerides), echocardiography and cardiac mitochondrial respiration were assessed in PI-treated rats ± various co-treatments. Our data reveal that PI treatment significantly lowered body weight and cardiac respiratory function while no significant changes were found for heart function and blood metabolite levels. Moreover, all co-treatments ameliorated the PI-induced decrease in body weight after 4 months of PI treatment, while RSV co-treatment enhanced cardiac mitochondrial respiratory capacity in PI-treated rats. This pilot study therefore provides novel hypotheses regarding RSV co-treatment that should be further assessed in greater detail. PMID:28107484

Zinc and calcium alter the relationship between mitochondrial respiration, ROS and membrane potential in rainbow trout (Oncorhynchus mykiss) liver mitochondria.

PubMed

Sharaf, Mahmoud S; Stevens, Don; Kamunde, Collins

2017-08-01

At excess levels, zinc (Zn) disrupts mitochondrial functional integrity and induces oxidative stress in aquatic organisms. Although much is known about the modulation of Zn toxicity by calcium (Ca) in fish, their interactions at the mitochondrial level have scarcely been investigated. Here we assessed the individual and combined effects of Zn and Ca on the relationship between mitochondrial respiration, ROS and membrane potential (ΔΨ mt ) in rainbow trout liver mitochondria. We tested if cation uptake through the mitochondrial calcium uniporter (MCU) is a prerequisite for Zn- and/or Ca-induced alteration of mitochondrial function. Furthermore, using our recently developed real-time multi-parametric method, we investigated the changes in respiration, ΔΨ mt , and reactive oxygen species (ROS, as hydrogen peroxide (H 2 O 2 )) release associated with Ca-induced mitochondrial depolarization imposed by transient and permanent openings of the mitochondrial permeability transition pore (mPTP). We found that independent of the MCU, Zn precipitated an immediate depolarization of the ΔΨ mt that was associated with relatively slow enhancement of H 2 O 2 release, inhibition of respiration and reversal of the positive correlation between ROS and ΔΨ mt . In contrast, an equitoxic dose of Ca caused transient depolarization, and stimulation of both respiration and H 2 O 2 release, effects that were completely abolished when the MCU was blocked. Contrary to our expectation that mitochondrial transition ROS Spike (mTRS) would be sensitive to both Zn and Ca, only Ca suppressed it. Moreover, Zn and Ca in combination immediately depolarized the ΔΨ mt , and caused transient and sustained stimulation of respiration and H 2 O 2 release, respectively. Lastly, we uncovered and characterized an mPTP-independent Ca-induced depolarization spike that was associated with exposure to moderately elevated levels of Ca. Importantly, we showed the stimulation of ROS release associated with highly elevated but not unrealistic Ca loads was not the cause but a result of mPTP opening in the high conductance mode. Copyright © 2017 Elsevier B.V. All rights reserved.

Paraoxonase 2 prevents the development of heart failure.

PubMed

Li, Wei; Kennedy, David; Shao, Zhili; Wang, Xi; Kamdar, Andre Klaassen; Weber, Malory; Mislick, Kayla; Kiefer, Kathryn; Morales, Rommel; Agatisa-Boyle, Brendan; Shih, Diana M; Reddy, Srinivasa T; Moravec, Christine S; Tang, W H Wilson

2018-05-02

Mitochondrial oxidation is a major source of reactive oxygen species (ROS) and mitochondrial dysfunction plays a central role in development of heart failure (HF). Paraoxonase 2 deficient (PON2-def) mitochondria are impaired in function. In this study, we tested whether PON2-def aggravates HF progression. Using qPCR, immunoblotting and lactonase activity assay, we demonstrate that PON2 activity was significantly decreased in failing hearts despite increased PON2 expression. To determine the cardiac-specific function of PON2, we performed heart transplantations in which PON2-def and wild type (WT) donor hearts were implanted into WT recipient mice. Beating scores of the donor hearts, assessed at 4 weeks post-transplantation, were significantly decreased in PON2-def hearts when compared to WT donor hearts. By using a transverse aortic constriction (TAC) model, we found PON2 deficiency significantly exacerbated left ventricular remodeling and cardiac fibrosis post-TAC. We further demonstrated PON2 deficiency significantly enhanced ROS generation in heart tissues post-TAC. ROS generation was measured through dihydroethidium (DHE) using high-pressure liquid chromatography (HPLC) with a fluorescent detector. By using neonatal cardiomyocytes treated with CoCl 2 to mimic hypoxia, we found PON2 deficiency dramatically increased ROS generation in the cardiomyocytes upon CoCl 2 treatment. In response to a short CoCl 2 exposure, cell viability and succinate dehydrogenase (SDH) activity assessed by MTT assay were significantly diminished in PON2-def cardiomyocytes compared to those in WT cardiomyocytes. PON2-def cardiomyocytes also had lower baseline SDH activity. By using adult mouse cardiomyocytes and mitochondrial ToxGlo assay, we found impaired cellular ATP generation in PON2-def cells compared to that in WT cells, suggesting that PON2 is necessary for proper mitochondrial function. Our study suggests a cardioprotective role for PON2 in both experimental and human heart failure, which may be associated with the ability of PON2 to improve mitochondrial function and diminish ROS generation. Copyright © 2018 Elsevier Inc. All rights reserved.

Roles of mitochondrial fragmentation and reactive oxygen species in mitochondrial dysfunction and myocardial insulin resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Tomoyuki; Saotome, Masao, E-mail: msaotome@hama-med.ac.jp; Nobuhara, Mamoru

Purpose: Evidence suggests an association between aberrant mitochondrial dynamics and cardiac diseases. Because myocardial metabolic deficiency caused by insulin resistance plays a crucial role in heart disease, we investigated the role of dynamin-related protein-1 (DRP1; a mitochondrial fission protein) in the pathogenesis of myocardial insulin resistance. Methods and Results: DRP1-expressing H9c2 myocytes, which had fragmented mitochondria with mitochondrial membrane potential (ΔΨ{sub m}) depolarization, exhibited attenuated insulin signaling and 2-deoxy-D-glucose (2-DG) uptake, indicating insulin resistance. Treatment of the DRP1-expressing myocytes with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (TMPyP) significantly improved insulin resistance and mitochondrial dysfunction. When myocytes were exposed to hydrogen peroxide (H{sub 2}O{sub 2}),more » they increased DRP1 expression and mitochondrial fragmentation, resulting in ΔΨ{sub m} depolarization and insulin resistance. When DRP1 was suppressed by siRNA, H{sub 2}O{sub 2}-induced mitochondrial dysfunction and insulin resistance were restored. Our results suggest that a mutual enhancement between DRP1 and reactive oxygen species could induce mitochondrial dysfunction and myocardial insulin resistance. In palmitate-induced insulin-resistant myocytes, neither DRP1-suppression nor TMPyP restored the ΔΨ{sub m} depolarization and impaired 2-DG uptake, however they improved insulin signaling. Conclusions: A mutual enhancement between DRP1 and ROS could promote mitochondrial dysfunction and inhibition of insulin signal transduction. However, other mechanisms, including lipid metabolite-induced mitochondrial dysfunction, may be involved in palmitate-induced insulin resistance. - Highlights: • DRP1 promotes mitochondrial fragmentation and insulin-resistance. • A mutual enhancement between DRP1 and ROS ipromotes insulin-resistance. • Palmitate increases DRP1 expression and induces insulin-resistance. • Inhibition of DRP or ROS failed to improve palmitate-induced insulin-resistance. • Mitochondrial dysfunction by lipid metabolites would induce insulin-resistance.« less

Agaricus blazei extract attenuates rotenone-induced apoptosis through its mitochondrial protective and antioxidant properties in SH-SY5Y neuroblastoma cells.

PubMed

Venkatesh Gobi, Veerappan; Rajasankar, Srinivasagam; Ramkumar, Muthu; Dhanalakshmi, Chinnasamy; Manivasagam, Thamilarasan; Justin Thenmozhi, Arokiasamy; Essa, Musthafa Mohamed; Chidambaram, Ranganathan

2018-02-01

The present study was aimed to find out the effect of Agaricus blazei mushroom extract against rotenone-induced cellular model. SH-SY5Y neuroblastoma cells are divided into four experimental groups (control, rotenone (100 nM), A. blazei (5 μg/ml) + rotenone (100 nM), and A. blazei alone treated) based on MTT assay, cells were allowed to measure the ROS, TBARS levels, and antioxidants activities. Finally, mitochondrial transmembrane potential (MMP) and expressions of apoptotic proteins were also analyzed. Pre-treatment with A. blazei significantly enhanced cell viability, attenuated rotenone-induced ROS, MMP, and apoptosis. Our results indicated that anti-apoptotic properties of this natural compound due to its antioxidant and mitochondrial protective function protect rotenone-induced cytotoxicity. Therefore, it may be concluded that A. blazei can be further developed as a promising drug for the treatment of Parkinson's disease (PD).

NAD⁺ repletion improves mitochondrial and stem cell function and enhances life span in mice.

PubMed

Zhang, Hongbo; Ryu, Dongryeol; Wu, Yibo; Gariani, Karim; Wang, Xu; Luan, Peiling; D'Amico, Davide; Ropelle, Eduardo R; Lutolf, Matthias P; Aebersold, Ruedi; Schoonjans, Kristina; Menzies, Keir J; Auwerx, Johan

2016-06-17

Adult stem cells (SCs) are essential for tissue maintenance and regeneration yet are susceptible to senescence during aging. We demonstrate the importance of the amount of the oxidized form of cellular nicotinamide adenine dinucleotide (NAD(+)) and its effect on mitochondrial activity as a pivotal switch to modulate muscle SC (MuSC) senescence. Treatment with the NAD(+) precursor nicotinamide riboside (NR) induced the mitochondrial unfolded protein response and synthesis of prohibitin proteins, and this rejuvenated MuSCs in aged mice. NR also prevented MuSC senescence in the mdx (C57BL/10ScSn-Dmd(mdx)/J) mouse model of muscular dystrophy. We furthermore demonstrate that NR delays senescence of neural SCs and melanocyte SCs and increases mouse life span. Strategies that conserve cellular NAD(+) may reprogram dysfunctional SCs and improve life span in mammals. Copyright © 2016, American Association for the Advancement of Science.

Thyroid hormone-induced oxidative stress.

PubMed

Venditti, P; Di Meo, S

2006-02-01

Hypermetabolic state in hyperthyroidism is associated with tissue oxidative injury. Available data indicate that hyperthyroid tissues exhibit an increased ROS and RNS production. The increased mitochondrial ROS generation is a side effect of the enhanced level of electron carriers, by which hyperthyroid tissues increase their metabolic capacity. Investigations of antioxidant defence system have returned controversial results. Moreover, other thyroid hormone-linked biochemical changes increase tissue susceptibility to oxidative challenge, which exacerbates the injury and dysfunction they suffer under stressful conditions. Mitochondria, as a primary target for oxidative stress, might account for hyperthyroidism linked tissue dysfunction. This is consistent with the inverse relationship found between functional recovery of ischemic hyperthyroid hearts and mitochondrial oxidative damage and respiration impairment. However, thyroid hormone-activated mitochondrial mechanisms provide protection against excessive tissue dysfunction, including increased expression of uncoupling proteins, proteolytic enzymes and transcriptional coactivator PGC-1, and stimulate opening of permeability transition pores.

Mitochondria-targeted antioxidant mitotempo protects mitochondrial function against amyloid beta toxicity in primary cultured mouse neurons.

PubMed

Hu, Hongtao; Li, Mo

2016-09-09

Mitochondrial defects including excess reactive oxygen species (ROS) production and compromised ATP generation are featured pathology in Alzheimer's disease (AD). Amyloid beta (Aβ)-mediated mitochondrial ROS overproduction disrupts intra-neuronal Redox balance, in turn exacerbating mitochondrial dysfunction leading to neuronal injury. Previous studies have found the beneficial effects of mitochondria-targeted antioxidants in preventing mitochondrial dysfunction and neuronal injury in AD animal and cell models, suggesting that mitochondrial ROS scavengers hold promise for the treatment of this neurological disorder. In this study, we have determined that mitotempo, a novel mitochondria-targeted antioxidant protects mitochondrial function from the toxicity of Aβ in primary cultured neurons. Our results showed that Aβ-promoted mitochondrial superoxide production and neuronal lipid oxidation were significantly suppressed by the application of mitotempo. Moreover, mitotempo also demonstrated protective effects on mitochondrial bioenergetics evidenced by preserved mitochondrial membrane potential, cytochrome c oxidase activity as well as ATP production. In addition, the Aβ-induced mitochondrial DNA (mtDNA) depletion and decreased expression levels of mtDNA replication-related DNA polymerase gamma (DNA pol γ) and Twinkle were substantially mitigated by mitotempo. Therefore, our study suggests that elimination of excess mitochondrial ROS rescues mitochondrial function in Aβ-insulted neruons; and mitotempo has the potential to be a promising therapeutic agent to protect mitochondrial and neuronal function in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial functionality in female reproduction.

PubMed

Gąsior, Łukasz; Daszkiewicz, Regina; Ogórek, Mateusz; Polański, Zbigniew

2017-01-04

In most animal species female germ cells are the source of mitochondrial genome for the whole body of individuals. As a source of mitochondrial DNA for future generations the mitochondria in the female germ line undergo dynamic quantitative and qualitative changes. In addition to maintaining the intact template of mitochondrial genome from one generation to another, mitochondrial role in oocytes is much more complex and pleiotropic. The quality of mitochondria determines the ability of meiotic divisions, fertilization ability, and activation after fertilization or sustaining development of a new embryo. The presence of normal number of functional mitochondria is also crucial for proper implantation and pregnancy maintaining. This article addresses issues of mitochondrial role and function in mammalian oocyte and presents new approaches in studies of mitochondrial function in female germ cells.

Mitochondrial morphology transitions and functions: implications for retrograde signaling?

PubMed Central

Picard, Martin; Shirihai, Orian S.; Gentil, Benoit J.

2013-01-01

In response to cellular and environmental stresses, mitochondria undergo morphology transitions regulated by dynamic processes of membrane fusion and fission. These events of mitochondrial dynamics are central regulators of cellular activity, but the mechanisms linking mitochondrial shape to cell function remain unclear. One possibility evaluated in this review is that mitochondrial morphological transitions (from elongated to fragmented, and vice-versa) directly modify canonical aspects of the organelle's function, including susceptibility to mitochondrial permeability transition, respiratory properties of the electron transport chain, and reactive oxygen species production. Because outputs derived from mitochondrial metabolism are linked to defined cellular signaling pathways, fusion/fission morphology transitions could regulate mitochondrial function and retrograde signaling. This is hypothesized to provide a dynamic interface between the cell, its genome, and the fluctuating metabolic environment. PMID:23364527

The extracellular redox state modulates mitochondrial function, gluconeogenesis, and glycogen synthesis in murine hepatocytes.

PubMed

Nocito, Laura; Kleckner, Amber S; Yoo, Elsia J; Jones Iv, Albert R; Liesa, Marc; Corkey, Barbara E

2015-01-01

Circulating redox state changes, determined by the ratio of reduced/oxidized pairs of different metabolites, have been associated with metabolic diseases. However, the pathogenic contribution of these changes and whether they modulate normal tissue function is unclear. As alterations in hepatic gluconeogenesis and glycogen metabolism are hallmarks that characterize insulin resistance and type 2 diabetes, we tested whether imposed changes in the extracellular redox state could modulate these processes. Thus, primary hepatocytes were treated with different ratios of the following physiological extracellular redox couples: β-hydroxybutyrate (βOHB)/acetoacetate (Acoc), reduced glutathione (GSH)/oxidized glutathione (GSSG), and cysteine/cystine. Exposure to a more oxidized ratio via extracellular βOHB/Acoc, GSH/GSSG, and cysteine/cystine in hepatocytes from fed mice increased intracellular hydrogen peroxide without causing oxidative damage. On the other hand, addition of more reduced ratios of extracellular βOHB/Acoc led to increased NAD(P)H and maximal mitochondrial respiratory capacity in hepatocytes. Greater βOHB/Acoc ratios were also associated with decreased β-oxidation, as expected with enhanced lipogenesis. In hepatocytes from fasted mice, a more extracellular reduced state of βOHB/Acoc led to increased alanine-stimulated gluconeogenesis and enhanced glycogen synthesis capacity from added glucose. Thus, we demonstrated for the first time that the extracellular redox state regulates the major metabolic functions of the liver and involves changes in intracellular NADH, hydrogen peroxide, and mitochondrial respiration. Because redox state in the blood can be communicated to all metabolically sensitive tissues, this work confirms the hypothesis that circulating redox state may be an important regulator of whole body metabolism and contribute to alterations associated with metabolic diseases.

The Extracellular Redox State Modulates Mitochondrial Function, Gluconeogenesis, and Glycogen Synthesis in Murine Hepatocytes

PubMed Central

Nocito, Laura; Kleckner, Amber S.; Yoo, Elsia J.; Jones IV, Albert R.; Liesa, Marc; Corkey, Barbara E.

2015-01-01

Circulating redox state changes, determined by the ratio of reduced/oxidized pairs of different metabolites, have been associated with metabolic diseases. However, the pathogenic contribution of these changes and whether they modulate normal tissue function is unclear. As alterations in hepatic gluconeogenesis and glycogen metabolism are hallmarks that characterize insulin resistance and type 2 diabetes, we tested whether imposed changes in the extracellular redox state could modulate these processes. Thus, primary hepatocytes were treated with different ratios of the following physiological extracellular redox couples: β-hydroxybutyrate (βOHB)/acetoacetate (Acoc), reduced glutathione (GSH)/oxidized glutathione (GSSG), and cysteine/cystine. Exposure to a more oxidized ratio via extracellular βOHB/Acoc, GSH/GSSG, and cysteine/cystine in hepatocytes from fed mice increased intracellular hydrogen peroxide without causing oxidative damage. On the other hand, addition of more reduced ratios of extracellular βOHB/Acoc led to increased NAD(P)H and maximal mitochondrial respiratory capacity in hepatocytes. Greater βOHB/Acoc ratios were also associated with decreased β-oxidation, as expected with enhanced lipogenesis. In hepatocytes from fasted mice, a more extracellular reduced state of βOHB/Acoc led to increased alanine-stimulated gluconeogenesis and enhanced glycogen synthesis capacity from added glucose. Thus, we demonstrated for the first time that the extracellular redox state regulates the major metabolic functions of the liver and involves changes in intracellular NADH, hydrogen peroxide, and mitochondrial respiration. Because redox state in the blood can be communicated to all metabolically sensitive tissues, this work confirms the hypothesis that circulating redox state may be an important regulator of whole body metabolism and contribute to alterations associated with metabolic diseases. PMID:25816337

Sulforaphane is anticonvulsant and improves mitochondrial function.

PubMed

Carrasco-Pozo, Catalina; Tan, Kah Ni; Borges, Karin

2015-12-01

The nuclear factor erythroid 2-related factor 2 pathway (Nrf2) has been previously identified to protect the brain against various impacts. Here, we investigated the effect of the Nrf2 activator sulforaphane in various seizure models and hippocampal mitochondrial bioenergetics. We found that daily injections of sulforaphane for 5 days elevated the seizure thresholds to 6 Hz stimulation and fluorothyl-, but not pentylenetetrazole-induced tonic seizures and protected mice against pilocarpine-induced status epilepticus (SE). Also, sulforaphane increased the antioxidant defences within hippocampal formations and blood plasma. In addition, sulforaphane treatment reduced the extent of hippocampal lipid peroxidation 24 h post-SE and protected hippocampal mitochondria against SE-induced reduction in state 2 and uncoupler-stimulated state 3 respiration. SE-mediated partial loss of rotenone-sensitive and complex II-driven respiration was reduced, consistent with the enhanced activities of complexes I and II in sulforaphane-treated SE mice. In mitochondria isolated from both no SE and SE mice, sulforaphane increased state 3 respiration and respiration linked to ATP synthesis, which may contribute to its anticonvulsant and antioxidant effects by providing more ATP for cellular vital and protective functions. However, sulforaphane did not prevent SE-induced hippocampal cell death. In conclusion, sulforaphane and/or Nrf2 activation are viable anticonvulsant strategies, which are antioxidant and enhance mitochondrial function, especially the ability to produce ATP. Sulforaphane was anticonvulsant in two acute mouse models of epilepsy and protected mice against pilocarpine-induced status epilepticus (SE). We also found antioxidant effects of sulforaphane in mouse plasma and hippocampal formations, exhibited by increased catalase and superoxide dismutase (SOD) activity, as well as increased abilities of hippocampal mitochondria to produce ATP. These effects likely underlie sulforaphane's anticonvulsant mechanisms of action. © 2015 International Society for Neurochemistry.

EET Enhances Renal Function in Obese Mice Resulting in Restoration of Mfn1/2 -HO-1 Signaling, and Decrease in Hypertension through Inhibition of Sodium Chloride Co-Transporter.

PubMed

Schragenheim, Joseph; Bellner, Lars; Cao, Jian; Singh, Shailendra P; Bamshad, David; McClung, John A; Maayan, Omri; Meissner, Aliza; Grant, Ilana; Stier, Charles T; Abraham, Nader G

2018-05-19

We have previously reported that epoxyeicosatrienoic acid (EET) has multiple beneficial effects on renal and adipose tissue function, in addition to its vasodilatory action; it increases insulin sensitivity and inhibits inflammation. In an examination of the signaling mechanisms by which EET reduces renal and peri-renal fat function, we hypothesized that EET ameliorates obesity-induced renal dysfunction by improving sodium excretion, reducing the sodium-chloride cotransporter NCC, lowering blood pressure, and enhancing mitochondrial and thermogenic gene levels in PGC-1α dependent mice. EET-agonist treatment normalized glucose metabolism, renal ENaC and NCC protein expression, urinary sodium excretion and blood pressure in obese (db/db) mice. A marked improvement in mitochondrial integrity, thermogenic genes, and PGC-1α-HO-1-adiponectin signaling occurred. Knockout of PGC-1α in EET-treated mice resulted in a reversal of these beneficial effects including a decrease in sodium excretion, elevation of blood pressure and an increase in the pro-inflammatory adipokine nephroblastoma overexpressed gene (NOV). In the elucidation of the effects of EET on peri-renal adipose tissue, EET increased adiponectin, mitochondrial integrity, thermogenic genes and decreased NOV, i.e. "Browning' peri-renal adipose phenotype that occurs under high fat diets. Taken together, these data demonstrate a critical role of an EET agonist in the restoration of healthy adipose tissue with reduced release of inflammatory molecules, such as AngII and NOV, thereby preventing their detrimental impact on sodium absorption and NCC levels and the development of obesity-induced renal dysfunction. Copyright © 2018. Published by Elsevier Inc.

Mitochondrial ferritin affects mitochondria by stabilizing HIF-1α in retinal pigment epithelium: implications for the pathophysiology of age-related macular degeneration.

PubMed

Wang, Xiying; Yang, Hongkuan; Yanagisawa, Daijiro; Bellier, Jean-Pierre; Morino, Katsutaro; Zhao, Shiguang; Liu, Ping; Vigers, Piers; Tooyama, Ikuo

2016-11-01

Mitochondrial ferritin (FtMt) is believed to play an antioxidant role via iron regulation, and FtMt gene mutation has been reported in age-related macular degeneration (AMD). However, little is known about FtMt's functions in the retina and any links to AMD. In this study, we observed age-related increase in FtMt and hypoxia-inducible factor-1α (HIF-1α) in murine retinal pigment epithelium (RPE). FtMt overexpression in ARPE-19 cells stabilized HIF-1α, and increased the secretion of vascular endothelial growth factor. Conversely, HIF-1α stabilization reduced the protein level of the mature, functional form of FtMt. FtMt-overexpressing ARPE-19 cells exhibited less oxidative phosphorylation but unchanged production of adenosine triphosphate, enhanced mitochondrial fission, and triggered mitophagy in a HIF-1α-dependent manner. These findings suggest that increased FtMt in RPE may be protective via triggering mitophagy but cause wet AMD by inducing neovascularization due to increased vascular endothelial growth factor secretion. However, reduced level of functional FtMt in RPE under hypoxia may allow dry AMD through susceptibility to age-related stress. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Mitochondria-Translocated PGK1 Functions as a Protein Kinase to Coordinate Glycolysis and the TCA Cycle in Tumorigenesis.

PubMed

Li, Xinjian; Jiang, Yuhui; Meisenhelder, Jill; Yang, Weiwei; Hawke, David H; Zheng, Yanhua; Xia, Yan; Aldape, Kenneth; He, Jie; Hunter, Tony; Wang, Liwei; Lu, Zhimin

2016-03-03

It is unclear how the Warburg effect that exemplifies enhanced glycolysis in the cytosol is coordinated with suppressed mitochondrial pyruvate metabolism. We demonstrate here that hypoxia, EGFR activation, and expression of K-Ras G12V and B-Raf V600E induce mitochondrial translocation of phosphoglycerate kinase 1 (PGK1); this is mediated by ERK-dependent PGK1 S203 phosphorylation and subsequent PIN1-mediated cis-trans isomerization. Mitochondrial PGK1 acts as a protein kinase to phosphorylate pyruvate dehydrogenase kinase 1 (PDHK1) at T338, which activates PDHK1 to phosphorylate and inhibit the pyruvate dehydrogenase (PDH) complex. This reduces mitochondrial pyruvate utilization, suppresses reactive oxygen species production, increases lactate production, and promotes brain tumorigenesis. Furthermore, PGK1 S203 and PDHK1 T338 phosphorylation levels correlate with PDH S293 inactivating phosphorylation levels and poor prognosis in glioblastoma patients. This work highlights that PGK1 acts as a protein kinase in coordinating glycolysis and the tricarboxylic acid (TCA) cycle, which is instrumental in cancer metabolism and tumorigenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Impaired adenosine monophosphate-activated protein kinase signalling in dorsal root ganglia neurons is linked to mitochondrial dysfunction and peripheral neuropathy in diabetes.

PubMed

Roy Chowdhury, Subir K; Smith, Darrell R; Saleh, Ali; Schapansky, Jason; Marquez, Alexandra; Gomes, Suzanne; Akude, Eli; Morrow, Dwane; Calcutt, Nigel A; Fernyhough, Paul

2012-06-01

Mitochondrial dysfunction occurs in sensory neurons and may contribute to distal axonopathy in animal models of diabetic neuropathy. The adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) signalling axis senses the metabolic demands of cells and regulates mitochondrial function. Studies in muscle, liver and cardiac tissues have shown that the activity of adenosine monophosphate-activated protein kinase and PGC-1α is decreased under hyperglycaemia. In this study, we tested the hypothesis that deficits in adenosine monophosphate-activated protein kinase/PGC-1α signalling in sensory neurons underlie impaired axonal plasticity, suboptimal mitochondrial function and development of neuropathy in rodent models of type 1 and type 2 diabetes. Phosphorylation and expression of adenosine monophosphate-activated protein kinase/PGC-1α and mitochondrial respiratory chain complex proteins were downregulated in dorsal root ganglia of both streptozotocin-diabetic rats and db/db mice. Adenoviral-mediated manipulation of endogenous adenosine monophosphate-activated protein kinase activity using mutant proteins modulated neurotrophin-directed neurite outgrowth in cultures of sensory neurons derived from adult rats. Addition of resveratrol to cultures of sensory neurons derived from rats after 3-5 months of streptozotocin-induced diabetes, significantly elevated adenosine monophosphate-activated protein kinase levels, enhanced neurite outgrowth and normalized mitochondrial inner membrane polarization in axons. The bioenergetics profile (maximal oxygen consumption rate, coupling efficiency, respiratory control ratio and spare respiratory capacity) was aberrant in cultured sensory neurons from streptozotocin-diabetic rats and was corrected by resveratrol treatment. Finally, resveratrol treatment for the last 2 months of a 5-month period of diabetes reversed thermal hypoalgesia and attenuated foot skin intraepidermal nerve fibre loss and reduced myelinated fibre mean axonal calibre in streptozotocin-diabetic rats. These data suggest that the development of distal axonopathy in diabetic neuropathy is linked to nutrient excess and mitochondrial dysfunction via defective signalling of the adenosine monophosphate-activated protein kinase/PGC-1α pathway.

Novel Cancer Therapeutics with Allosteric Modulation of the Mitochondrial C-Raf-DAPK Complex by Raf Inhibitor Combination Therapy.

PubMed

Tsai, Yi-Ta; Chuang, Mei-Jen; Tang, Shou-Hung; Wu, Sheng-Tang; Chen, Yu-Chi; Sun, Guang-Huan; Hsiao, Pei-Wen; Huang, Shih-Ming; Lee, Hwei-Jen; Yu, Cheng-Ping; Ho, Jar-Yi; Lin, Hui-Kuan; Chen, Ming-Rong; Lin, Chung-Chih; Chang, Sun-Yran; Lin, Victor C; Yu, Dah-Shyong; Cha, Tai-Lung

2015-09-01

Mitochondria are the powerhouses of cells. Mitochondrial C-Raf is a potential cancer therapeutic target, as it regulates mitochondrial function and is localized to the mitochondria by its N-terminal domain. However, Raf inhibitor monotherapy can induce S338 phosphorylation of C-Raf (pC-Raf(S338)) and impede therapy. This study identified the interaction of C-Raf with S308 phosphorylated DAPK (pDAPK(S308)), which together became colocalized in the mitochondria to facilitate mitochondrial remodeling. Combined use of the Raf inhibitors sorafenib and GW5074 had synergistic anticancer effects in vitro and in vivo, but targeted mitochondrial function, rather than the canonical Raf signaling pathway. C-Raf depletion in knockout MEF(C-Raf-/-) or siRNA knockdown ACHN renal cancer cells abrogated the cytotoxicity of combination therapy. Crystal structure simulation showed that GW5074 bound to C-Raf and induced a C-Raf conformational change that enhanced sorafenib-binding affinity. In the presence of pDAPK(S308), this drug-target interaction compromised the mitochondrial targeting effect of the N-terminal domain of C-Raf, which induced two-hit damages to cancer cells. First, combination therapy facilitated pC-Raf(S338) and pDAPK(S308) translocation from mitochondria to cytoplasm, leading to mitochondrial dysfunction and reactive oxygen species (ROS) generation. Second, ROS facilitated PP2A-mediated dephosphorylation of pDAPK(S308) to DAPK. PP2A then dissociated from the C-Raf-DAPK complex and induced profound cancer cell death. Increased pDAPK(S308) modification was also observed in renal cancer tissues, which correlated with poor disease-free survival and poor overall survival in renal cancer patients. Besides mediating the anticancer effect, pDAPK(S308) may serve as a predictive biomarker for Raf inhibitors combination therapy, suggesting an ideal preclinical model that is worthy of clinical translation. ©2015 American Association for Cancer Research.

Loss of Mitochondrial Function Impairs Lysosomes.

PubMed

Demers-Lamarche, Julie; Guillebaud, Gérald; Tlili, Mouna; Todkar, Kiran; Bélanger, Noémie; Grondin, Martine; Nguyen, Angela P; Michel, Jennifer; Germain, Marc

2016-05-06

Alterations in mitochondrial function, as observed in neurodegenerative diseases, lead to disrupted energy metabolism and production of damaging reactive oxygen species. Here, we demonstrate that mitochondrial dysfunction also disrupts the structure and function of lysosomes, the main degradation and recycling organelle. Specifically, inhibition of mitochondrial function, following deletion of the mitochondrial protein AIF, OPA1, or PINK1, as well as chemical inhibition of the electron transport chain, impaired lysosomal activity and caused the appearance of large lysosomal vacuoles. Importantly, our results show that lysosomal impairment is dependent on reactive oxygen species. Given that alterations in both mitochondrial function and lysosomal activity are key features of neurodegenerative diseases, this work provides important insights into the etiology of neurodegenerative diseases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Comparative effects of avocado oil and losartan on blood pressure, renal vascular function, and mitochondrial oxidative stress in hypertensive rats.

PubMed

Márquez-Ramírez, Cristian Adrián; Hernández de la Paz, José Lucio; Ortiz-Avila, Omar; Raya-Farias, Andrés; González-Hernández, Juan Carlos; Rodríguez-Orozco, Alain Raimundo; Salgado-Garciglia, Rafael; Saavedra-Molina, Alfredo; Godínez-Hernández, Daniel; Cortés-Rojo, Christian

2018-03-20

Angiotensin II (Ang-II) antagonism alleviates hypertensive kidney damage by improving mitochondrial function and decreasing oxidative stress. This condition also is associated with altered renal vascular tone due to enhanced constriction by Ang-II. Thus, approaches ameliorating these events are desirable to alleviate kidney damage. Avocado oil, a source of antioxidants and oleic acid, is known to improve mitochondrial function, while oleic acid has antihypertensive effects. Therefore, the aim of this study was to test whether avocado oil counteracts, to a similar degree as the Ang-II blocker losartan, the deleterious effects of hypertension on blood pressure, renal vascular performance, kidney mitochondrial function, and oxidative stress. Hypertensive rats induced with Nω-nitro-l-arginine methyl ester (L-NAME) were supplemented during 45 d with avocado oil or losartan. Vascular responses were analyzed in perfused kidney. Membrane potential, reactive oxygen species levels, and glutathione were analyzed in isolated kidney mitochondria. In hypertensive rats, avocado oil decreased 21.2% and 15.5% diastolic and systolic blood pressures, respectively, and alleviated impaired renal vasodilation. Hypertension decreased membrane potential by 83.7% and augmented reactive oxygen species levels by 51% in mitochondria fueled with a complex I substrate, whereas it augmented the levels of oxidized glutathione in 48%. These alterations were normalized by avocado oil at a comparable degree to losartan. Because avocado oil mimicked the effects of losartan, we propose that the effects of avocado oil might be mediated by decreasing the actions of Ang-II on mitochondria. These results suggest that avocado oil intake might be a nutritional approach to attenuate the deleterious effects of hypertension on kidney. Copyright © 2018 Elsevier Inc. All rights reserved.

Cold ischemia contributes to the development of chronic rejection and mitochondrial injury after cardiac transplantation.

PubMed

Schneeberger, Stefan; Amberger, Albert; Mandl, Julia; Hautz, Theresa; Renz, Oliver; Obrist, Peter; Meusburger, Hugo; Brandacher, Gerald; Mark, Walter; Strobl, Daniela; Troppmair, Jakob; Pratschke, Johann; Margreiter, Raimund; Kuznetsov, Andrey V

2010-12-01

Chronic rejection (CR) remains an unsolved hurdle for long-term heart transplant survival. The effect of cold ischemia (CI) on progression of CR and the mechanisms resulting in functional deficit were investigated by studying gene expression, mitochondrial function, and enzymatic activity. Allogeneic (Lew→F344) and syngeneic (Lew→Lew) heart transplantations were performed with or without 10 h of CI. After evaluation of myocardial contraction, hearts were excised at 2, 10, 40, and 60 days for investigation of vasculopathy, gene expression, enzymatic activities, and mitochondrial respiration. Gene expression studies identified a gene cluster coding for subunits of the mitochondrial electron transport chain regulated in response to CI and CR. Myocardial performance, mitochondrial function, and mitochondrial marker enzyme activities declined in all allografts with time after transplantation. These declines were more rapid and severe in CI allografts (CR-CI) and correlated well with progression of vasculopathy and fibrosis. Mitochondria related gene expression and mitochondrial function are substantially compromised with the progression of CR and show that CI impacts on progression, gene profile, and mitochondrial function of CR. Monitoring mitochondrial function and enzyme activity might allow for earlier detection of CR and cardiac allograft dysfunction. © 2010 The Authors. Journal compilation © 2010 European Society for Organ Transplantation.

Mitoprotective antioxidant EUK-134 stimulates fatty acid oxidation and prevents hypertrophy in H9C2 cells.

PubMed

Purushothaman, Sreeja; Nair, R Renuka

2016-09-01

Oxidative stress is an important contributory factor for the development of cardiovascular diseases like hypertension-induced hypertrophy. Mitochondrion is the major source of reactive oxygen species. Hence, protecting mitochondria from oxidative damage can be an effective therapeutic strategy for the prevention of hypertensive heart disease. Conventional antioxidants are not likely to be cardioprotective, as they cannot protect mitochondria from oxidative damage. EUK-134 is a salen-manganese complex with superoxide dismutase and catalase activity. The possible role of EUK-134, a mitoprotective antioxidant, in the prevention of hypertrophy of H9C2 cells was examined. The cells were stimulated with phenylephrine (50 μM), and hypertrophy was assessed based on cell volume and expression of brain natriuretic peptide and calcineurin. Enhanced myocardial lipid peroxidation and protein carbonyl content, accompanied by nuclear factor-kappa B gene expression, confirmed the presence of oxidative stress in hypertrophic cells. Metabolic shift was evident from reduction in the expression of medium-chain acyl-CoA dehydrogenase. Mitochondrial oxidative stress was confirmed by the reduced expression of mitochondria-specific antioxidant peroxiredoxin-3 and enhanced mitochondrial superoxide production. Compromised mitochondrial function was apparent from reduced mitochondrial membrane potential. Pretreatment with EUK-134 (10 μM) was effective in the prevention of hypertrophic changes in H9C2 cells, reduction of oxidative stress, and prevention of metabolic shift. EUK-134 treatment improved the oxidative status of mitochondria and reversed hypertrophy-induced reduction of mitochondrial membrane potential. Supplementation with EUK-134 is therefore identified as a novel approach to attenuate cardiac hypertrophy and lends scope for the development of EUK-134 as a therapeutic agent in the management of human cardiovascular disease.

Eicosapentaenoic acid but not docosahexaenoic acid restores skeletal muscle mitochondrial oxidative capacity in old mice

PubMed Central

Johnson, Matthew L; Lalia, Antigoni Z; Dasari, Surendra; Pallauf, Maximilian; Fitch, Mark; Hellerstein, Marc K; Lanza, Ian R

2015-01-01

Mitochondrial dysfunction is often observed in aging skeletal muscle and is implicated in age-related declines in physical function. Early evidence suggests that dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve mitochondrial function. Here, we show that 10 weeks of dietary eicosapentaenoic acid (EPA) supplementation partially attenuated the age-related decline in mitochondrial function in mice, but this effect was not observed with docosahexaenoic acid (DHA). The improvement in mitochondrial function with EPA occurred in the absence of any changes in mitochondrial abundance or biogenesis, which was evaluated from RNA sequencing, large-scale proteomics, and direct measurements of muscle mitochondrial protein synthesis rates. We find that EPA improves muscle protein quality, specifically by decreasing mitochondrial protein carbamylation, a post-translational modification that is driven by inflammation. These results demonstrate that EPA attenuated the age-related loss of mitochondrial function and improved mitochondrial protein quality through a mechanism that is likely linked with anti-inflammatory properties of n-3 PUFAs. Furthermore, we demonstrate that EPA and DHA exert some common biological effects (anticoagulation, anti-inflammatory, reduced FXR/RXR activation), but also exhibit many distinct biological effects, a finding that underscores the importance of evaluating the therapeutic potential of individual n-3 PUFAs. PMID:26010060

Mitochondrial impairments contribute to spatial learning and memory dysfunction induced by chronic tramadol administration in rat: Protective effect of physical exercise.

PubMed

Mehdizadeh, Hajar; Pourahmad, Jalal; Taghizadeh, Ghorban; Vousooghi, Nasim; Yoonessi, Ali; Naserzadeh, Parvaneh; Behzadfar, Ladan; Rouini, Mohammad Reza; Sharifzadeh, Mohammad

2017-10-03

Despite the worldwide use of tramadol, few studies have been conducted about its effects on memory and mitochondrial function, and controversial results have been reported. Recently, there has been an increasing interest in physical exercise as a protective approach to neuronal and cognitive impairments. Therefore, the aim of this study was to investigate the effects of physical exercise on spatial learning and memory and brain mitochondrial function in tramadol-treated rats. After completion of 2-week (short-term) and 4-week (long-term) treadmill exercise regimens, male Wistar rats received tramadol (20, 40, 80mg/kg/day) intraperitoneally for 30days. Then spatial learning and memory was assessed by Morris water maze test (MWM). Moreover, brain mitochondrial function was evaluated by determination of mitochondrial reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP), mitochondrial swelling and cytochrome c release from mitochondria. Chronic administration of tramadol impaired spatial learning and memory as well as brain mitochondrial function as indicated by increased ROS level, MMP collapse, increased mitochondrial swelling and cytochrome c release from mitochondria. Conversely, treadmill exercise significantly attenuated the impairments of spatial learning and memory and brain mitochondrial dysfunction induced by tramadol. The results revealed that chronic tramadol treatment caused memory impairments through induction of brain mitochondrial dysfunction. Furthermore, pre-exposure to physical exercise markedly mitigated these impairments through its positive effects on brain mitochondrial function. Copyright © 2017. Published by Elsevier Inc.

Intravitreal delivery of AAV-NDI1 provides functional benefit in a murine model of Leber hereditary optic neuropathy.

PubMed

Chadderton, Naomi; Palfi, Arpad; Millington-Ward, Sophia; Gobbo, Oliverio; Overlack, Nora; Carrigan, Matthew; O'Reilly, Mary; Campbell, Matthew; Ehrhardt, Carsten; Wolfrum, Uwe; Humphries, Peter; Kenna, Paul F; Farrar, G Jane

2013-01-01

Leber hereditary optic neuropathy (LHON) is a mitochondrially inherited form of visual dysfunction caused by mutations in several genes encoding subunits of the mitochondrial respiratory NADH-ubiquinone oxidoreductase complex (complex I). Development of gene therapies for LHON has been impeded by genetic heterogeneity and the need to deliver therapies to the mitochondria of retinal ganglion cells (RGCs), the cells primarily affected in LHON. The therapy under development entails intraocular injection of a nuclear yeast gene NADH-quinone oxidoreductase (NDI1) that encodes a single subunit complex I equivalent and as such is mutation independent. NDI1 is imported into mitochondria due to an endogenous mitochondrial localisation signal. Intravitreal injection represents a clinically relevant route of delivery to RGCs not previously used for NDI1. In this study, recombinant adenoassociated virus (AAV) serotype 2 expressing NDI1 (AAV-NDI1) was shown to protect RGCs in a rotenone-induced murine model of LHON. AAV-NDI1 significantly reduced RGC death by 1.5-fold and optic nerve atrophy by 1.4-fold. This led to a significant preservation of retinal function as assessed by manganese enhanced magnetic resonance imaging and optokinetic responses. Intraocular injection of AAV-NDI1 overcomes many barriers previously associated with developing therapies for LHON and holds great therapeutic promise for a mitochondrial disorder for which there are no effective therapies.

Hexokinase II acts through UCP3 to suppress mitochondrial reactive oxygen species production and maintain aerobic respiration.

PubMed

Mailloux, Ryan J; Dumouchel, Tyler; Aguer, Céline; deKemp, Rob; Beanlands, Rob; Harper, Mary-Ellen

2011-07-15

UCP3 (uncoupling protein-3) mitigates mitochondrial ROS (reactive oxygen species) production, but the mechanisms are poorly understood. Previous studies have also examined UCP3 effects, including decreased ROS production, during metabolic states when fatty acid oxidation is high (e.g. a fasting state). However, the role of UCP3 when carbohydrate oxidation is high (e.g. fed state) has remained largely unexplored. In the present study, we show that mitochondrial-bound HK (hexokinase) II curtails oxidative stress and enhances aerobic metabolism of glucose in the fed state in a UCP3-dependent manner. Genetic knockout or inhibition of UCP3 significantly decreased mitochondrial-bound HKII. Furthermore, UCP3 was required for the HKII-mediated decrease in mitochondrial ROS emission. Intriguingly, the UCP3-mediated modulation of mitochondria-associated HKII was only observed in cells cultured under high-glucose conditions. UCP3 was required to maintain high rates of aerobic metabolism in high-glucose-treated cells and in muscle of fed mice. Deficiency in UCP3 resulted in a metabolic shift that favoured anaerobic glycolytic metabolism, increased glucose uptake and increased sensitivity to oxidative challenge. PET (positron emission tomography) of [18F]fluoro-deoxyglucose uptake confirmed these findings in UCP3-knockout and wild-type mice. Collectively, our findings link the anti-oxidative and metabolic functions of UCP3 through a surprising molecular connection with mitochondrial-bound HKII.

Cellular determinants involving mitochondrial dysfunction, oxidative stress and apoptosis correlate with the synergic cytotoxicity of epigallocatechin-3-gallate and menadione in human leukemia Jurkat T cells.

PubMed

Tofolean, Ioana Teodora; Ganea, Constanta; Ionescu, Diana; Filippi, Alexandru; Garaiman, Alexandru; Goicea, Alexandru; Gaman, Mihnea-Alexandru; Dimancea, Alexandru; Baran, Irina

2016-01-01

We have investigated the growth-suppressive action of epigallocatechin-3-gallate (EGCG) on human leukemia Jurkat T cells. Results show a strong correlation between the dose-dependent reduction of clonogenic survival following acute EGCG treatments and the EGCG-induced decline of the mitochondrial level of Ca(2+). The cell killing ability of EGCG was synergistically enhanced by menadione. In addition, the cytotoxic effect of EGCG applied alone or in combination with menadione was accompanied by apoptosis induction. We also observed that in acute treatments EGCG displays strong antioxidant properties in the intracellular milieu, but concurrently triggers some oxidative stress generating mechanisms that can fully develop on a longer timescale. In parallel, EGCG dose-dependently induced mitochondrial depolarization during exposure, but this condition was subsequently reversed to a persistent hyperpolarized mitochondrial state that was dependent on the activity of respiratory Complex I. Fluorimetric measurements suggest that EGCG is a mitochondrial Complex III inhibitor and indicate that EGCG evokes a specific cellular fluorescence with emission at 400nm and two main excitation bands (at 330nm and 350nm) that may originate from a mitochondrial supercomplex containing dimeric Complex III and dimeric ATP-synthase, and therefore could provide a valuable means to characterize the functional properties of the respiratory chain. Copyright © 2015 Elsevier Ltd. All rights reserved.

ATP Maintenance via Two Types of ATP Regulators Mitigates Pathological Phenotypes in Mouse Models of Parkinson's Disease.

PubMed

Nakano, Masaki; Imamura, Hiromi; Sasaoka, Norio; Yamamoto, Masamichi; Uemura, Norihito; Shudo, Toshiyuki; Fuchigami, Tomohiro; Takahashi, Ryosuke; Kakizuka, Akira

2017-08-01

Parkinson's disease is assumed to be caused by mitochondrial dysfunction in the affected dopaminergic neurons in the brain. We have recently created small chemicals, KUSs (Kyoto University Substances), which can reduce cellular ATP consumption. By contrast, agonistic ligands of ERRs (estrogen receptor-related receptors) are expected to raise cellular ATP levels via enhancing ATP production. Here, we show that esculetin functions as an ERR agonist, and its addition to culture media enhances glycolysis and mitochondrial respiration, leading to elevated cellular ATP levels. Subsequently, we show the neuroprotective efficacies of KUSs, esculetin, and GSK4716 (an ERRγ agonist) against cell death in Parkinson's disease models. In the surviving neurons, ATP levels and expression levels of α-synuclein and CHOP (an ER stress-mediated cell death executor) were all rectified. We propose that maintenance of ATP levels, by inhibiting ATP consumption or enhancing ATP production, or both, would be a promising therapeutic strategy for Parkinson's disease. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

MAP4 Mechanism that Stabilizes Mitochondrial Permeability Transition in Hypoxia: Microtubule Enhancement and DYNLT1 Interaction with VDAC1

PubMed Central

Zhang, Yi-ming; Zhang, Jia-ping; Hu, Jiong-yu; Zhang, Qiong; Dai, Xia; Teng, Miao; Zhang, Dong-xia; Huang, Yue-sheng

2011-01-01

Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption. In this study, we established the hypoxic (1% O2) cell models of rat cardiomyocytes, H9c2 and HeLa cells to further test MAP4 function. We demonstrated that increase in the pool of MAP4 could promote the stabilization of MT networks by increasing the synthesis and polymerization of tubulin in hypoxia. Results showed MAP4 overexpression could enhance cell viability and ATP content under hypoxic conditions. Subsequently we employed a yeast two-hybrid system to tag a protein interacting with mitochondria, dynein light chain Tctex-type 1 (DYNLT1), by hVDAC1 bait. We confirmed that DYNLT1 had protein-protein interactions with voltage-dependent anion channel 1 (VDAC1) using co-immunoprecipitation; and immunofluorescence technique showed that DYNLT1 was closely associated with MTs and VDAC1. Furthermore, DYNLT1 interactions with MAP4 were explored using a knockdown technique. We thus propose two possible mechanisms triggered by MAP4: (1) stabilization of MT networks, (2) DYNLT1 modulation, which is connected with VDAC1, and inhibition of hypoxia-induced mitochondrial permeabilization. PMID:22164227

Reduction of protein translation and activation of autophagy protect against PINK1 pathogenesis in Drosophila melanogaster.

PubMed

Liu, Song; Lu, Bingwei

2010-12-09

Mutations in PINK1 and Parkin cause familial, early onset Parkinson's disease. In Drosophila melanogaster, PINK1 and Parkin mutants show similar phenotypes, such as swollen and dysfunctional mitochondria, muscle degeneration, energy depletion, and dopaminergic (DA) neuron loss. We previously showed that PINK1 and Parkin genetically interact with the mitochondrial fusion/fission pathway, and PINK1 and Parkin were recently proposed to form a mitochondrial quality control system that involves mitophagy. However, the in vivo relationships among PINK1/Parkin function, mitochondrial fission/fusion, and autophagy remain unclear; and other cellular events critical for PINK1 pathogenesis remain to be identified. Here we show that PINK1 genetically interacted with the protein translation pathway. Enhanced translation through S6K activation significantly exacerbated PINK1 mutant phenotypes, whereas reduction of translation showed suppression. Induction of autophagy by Atg1 overexpression also rescued PINK1 mutant phenotypes, even in the presence of activated S6K. Downregulation of translation and activation of autophagy were already manifested in PINK1 mutant, suggesting that they represent compensatory cellular responses to mitochondrial dysfunction caused by PINK1 inactivation, presumably serving to conserve energy. Interestingly, the enhanced PINK1 mutant phenotype in the presence of activated S6K could be fully rescued by Parkin, apparently in an autophagy-independent manner. Our results reveal complex cellular responses to PINK1 inactivation and suggest novel therapeutic strategies through manipulation of the compensatory responses.

Reduction of Protein Translation and Activation of Autophagy Protect against PINK1 Pathogenesis in Drosophila melanogaster

PubMed Central

Liu, Song; Lu, Bingwei

2010-01-01

Mutations in PINK1 and Parkin cause familial, early onset Parkinson's disease. In Drosophila melanogaster, PINK1 and Parkin mutants show similar phenotypes, such as swollen and dysfunctional mitochondria, muscle degeneration, energy depletion, and dopaminergic (DA) neuron loss. We previously showed that PINK1 and Parkin genetically interact with the mitochondrial fusion/fission pathway, and PINK1 and Parkin were recently proposed to form a mitochondrial quality control system that involves mitophagy. However, the in vivo relationships among PINK1/Parkin function, mitochondrial fission/fusion, and autophagy remain unclear; and other cellular events critical for PINK1 pathogenesis remain to be identified. Here we show that PINK1 genetically interacted with the protein translation pathway. Enhanced translation through S6K activation significantly exacerbated PINK1 mutant phenotypes, whereas reduction of translation showed suppression. Induction of autophagy by Atg1 overexpression also rescued PINK1 mutant phenotypes, even in the presence of activated S6K. Downregulation of translation and activation of autophagy were already manifested in PINK1 mutant, suggesting that they represent compensatory cellular responses to mitochondrial dysfunction caused by PINK1 inactivation, presumably serving to conserve energy. Interestingly, the enhanced PINK1 mutant phenotype in the presence of activated S6K could be fully rescued by Parkin, apparently in an autophagy-independent manner. Our results reveal complex cellular responses to PINK1 inactivation and suggest novel therapeutic strategies through manipulation of the compensatory responses. PMID:21151574

Effect of CoQ homologues on reactive oxygen generation by mitochondria.

PubMed

Imada, Isuke; Sato, Eisuke F; Kira, Yukimi; Inoue, Masayasu

2008-01-01

Effect of CoQ compounds (Qs) on reactive oxygen (ROS) generation by mitochondrial complex I was studied using rat liver mitochondria and chemiluminescence probe L012. Kinetic analysis revealed that short chain Qs, such as Q2 and idebenone enhanced ROS generation by mitochondrial NADH oxidase system by a succinate-inhibitable mechanism. Lipid peroxidation in mitochondrial membranes induced by NADH and iron was inhibited by short chain Qs. The inhibitory activity was enhanced by co-oxidation of succinate as determined by chemiluminescence method and by electron spin resonance spectroscopy. These results suggested that the reduced form of short chain Qs inhibited mitochondrial ROS generation and lipid peroxidation.

Energy metabolism determines the sensitivity of human hepatocellular carcinoma cells to mitochondrial inhibitors and biguanide drugs.

PubMed

Hsu, Chia-Chi; Wu, Ling-Chia; Hsia, Cheng-Yuan; Yin, Pen-Hui; Chi, Chin-Wen; Yeh, Tien-Shun; Lee, Hsin-Chen

2015-09-01

Human hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide particularly in Asia. Deregulation of cellular energetics was recently included as one of the cancer hallmarks. Compounds that target the mitochondria in cancer cells were proposed to have therapeutic potential. Biguanide drugs which inhibit mitochondrial complex I and repress mTOR signaling are clinically used to treat type 2 diabetes mellitus patients (T2DM) and were recently found to reduce the risk of HCC in T2DM patients. However, whether alteration of energy metabolism is involved in regulating the sensitivity of HCC to biguanide drugs is still unclear. In the present study, we treated four HCC cell lines with mitochondrial inhibitors (rotenone and oligomycin) and biguanide drugs (metformin and phenformin), and found that the HCC cells which had a higher mitochondrial respiration rate were more sensitive to these treatments; whereas the HCC cells which exhibited higher glycolysis were more resistant. When glucose was replaced by galactose in the medium, the altered energy metabolism from glycolysis to mitochondrial respiration in the HCC cells enhanced the cellular sensitivity to mitochondrial inhibitors and biguanides. The energy metabolism change enhanced AMP-activated protein kinase (AMPK) activation, mTOR repression and downregulation of cyclin D1 and Mcl-1 in response to the mitochondrial inhibitors and biguanides. In conclusion, our results suggest that increased mitochondrial oxidative metabolism upregulates the sensitivity of HCC to biguanide drugs. Enhancing the mitochondrial oxidative metabolism in combination with biguanide drugs may be a therapeutic strategy for HCC.

Sources, mechanisms, and consequences of chemical-induced mitochondrial toxicity

PubMed Central

Meyer, Joel N.; Chan, Sherine S. L.

2017-01-01

Mitochondrial function is critical for health, as demonstrated by the effects of mitochondrial toxicity, mutations in genes encoding mitochondrial proteins, and the role of mitochondrial dysfunction in many chronic diseases. However, much basic mitochondrial biology is still being discovered. Furthermore, the details of how different environmental exposures affect mitochondria, how mitochondria respond to stressors, and how genetic variation affecting mitochondrial function alters response to exposures are areas of rapid research growth. This Special Issue was created to highlight and review cutting-edge areas of research into chemical effects on mitochondrial function. We anticipate that it will stimulate additional research into the mechanisms by which chemical exposures impact mitochondria, the biological processes that protect mitochondria from such impacts, and the health consequences that result when defense and homeostatic mechanisms are overcome. PMID:28627407

Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

PubMed

Zuo, Li; Pannell, Benjamin K; Re, Anthony T; Best, Thomas M; Wagner, Peter D

2015-12-01

Po2 cycling, often referred to as intermittent hypoxia, involves exposing tissues to brief cycles of low oxygen environments immediately followed by hyperoxic conditions. After experiencing long-term hypoxia, muscle can be damaged during the subsequent reintroduction of oxygen, which leads to muscle dysfunction via reperfusion injury. The protective effect and mechanism behind Po2 cycling in skeletal muscle during reoxygenation have yet to be fully elucidated. We hypothesize that Po2 cycling effectively increases muscle fatigue resistance through reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and certain mitochondrial channels during reoxygenation. Using a dihydrofluorescein fluorescent probe, we detected the production of ROS in mouse diaphragmatic skeletal muscle in real time under confocal microscopy. Muscles treated with Po2 cycling displayed significantly attenuated ROS levels (n = 5; P < 0.001) as well as enhanced force generation compared with controls during reperfusion (n = 7; P < 0.05). We also used inhibitors for signaling molecules or membrane channels such as ROS, Akt, ERK, as well as chemical stimulators to close mitochondrial ATP-sensitive potassium channel (KATP) or open mitochondrial permeability transition pore (mPTP). All these blockers or stimulators abolished improved muscle function with Po2 cycling treatment. This current investigation has discovered a correlation between KATP and mPTP and the Po2 cycling pathway in diaphragmatic skeletal muscle. Thus we have identified a unique signaling pathway that may involve ROS, Akt, ERK, and mitochondrial channels responsible for Po2 cycling protection during reoxygenation conditions in the diaphragm. Copyright © 2015 the American Physiological Society.

Mitochondrial and Plasma Membrane Pools of Stomatin-Like Protein 2 Coalesce at the Immunological Synapse during T Cell Activation

PubMed Central

Christie, Darah A.; Kirchhof, Mark G.; Vardhana, Santosh; Dustin, Michael L.; Madrenas, Joaquín

2012-01-01

Stomatin-like protein 2 (SLP-2) is a member of the stomatin – prohibitin – flotillin – HflC/K (SPFH) superfamily. Recent evidence indicates that SLP-2 is involved in the organization of cardiolipin-enriched microdomains in mitochondrial membranes and the regulation of mitochondrial biogenesis and function. In T cells, this role translates into enhanced T cell activation. Although the major pool of SLP-2 is associated with mitochondria, we show here that there is an additional pool of SLP-2 associated with the plasma membrane of T cells. Both plasma membrane-associated and mitochondria-associated pools of SLP-2 coalesce at the immunological synapse (IS) upon T cell activation. SLP-2 is not required for formation of IS nor for the re-localization of mitochondria to the IS because SLP-2-deficient T cells showed normal re-localization of these organelles in response to T cell activation. Interestingly, upon T cell activation, we found the surface pool of SLP-2 mostly excluded from the central supramolecular activation complex, and enriched in the peripheral area of the IS where signalling TCR microclusters are located. Based on these results, we propose that SLP-2 facilitates the compartmentalization not only of mitochondrial membranes but also of the plasma membrane into functional microdomains. In this latter location, SLP-2 may facilitate the optimal assembly of TCR signalosome components. Our data also suggest that there may be a net exchange of membrane material between mitochondria and plasma membrane, explaining the presence of some mitochondrial proteins in the plasma membrane. PMID:22623988

Cholesterol contributes to dopamine-neuronal loss in MPTP mouse model of Parkinson’s disease: Involvement of mitochondrial dysfunctions and oxidative stress

PubMed Central

Kumar, Sanjeev; Giri, Anirudha; Sandhir, Rajat

2017-01-01

Hypercholesterolemia is a known contributor to the pathogenesis of Alzheimer’s disease while its role in the occurrence of Parkinson’s disease (PD) is only conjecture and far from conclusive. Altered antioxidant homeostasis and mitochondrial functions are the key mechanisms in loss of dopaminergic neurons in the substantia nigra (SN) region of the midbrain in PD. Hypercholesterolemia is reported to cause oxidative stress and mitochondrial dysfunctions in the cortex and hippocampus regions of the brain in rodents. However, the impact of hypercholesterolemia on the midbrain dopaminergic neurons in animal models of PD remains elusive. We tested the hypothesis that hypercholesterolemia in MPTP model of PD would potentiate dopaminergic neuron loss in SN by disrupting mitochondrial functions and antioxidant homeostasis. It is evident from the present study that hypercholesterolemia in naïve animals caused dopamine neuronal loss in SN with subsequent reduction in striatal dopamine levels producing motor impairment. Moreover, in the MPTP model of PD, hypercholesterolemia exacerbated MPTP-induced reduction of striatal dopamine as well as dopaminergic neurons in SN with motor behavioral depreciation. Activity of mitochondrial complexes, mainly complex-I and III, was impaired severely in the nigrostriatal pathway of hypercholesterolemic animals treated with MPTP. Hypercholesterolemia caused oxidative stress in the nigrostriatal pathway with increased generation of hydroxyl radicals and enhanced activity of antioxidant enzymes, which were further aggravated in the hypercholesterolemic mice with Parkinsonism. In conclusion, our findings provide evidence of increased vulnerability of the midbrain dopaminergic neurons in PD with hypercholesterolemia. PMID:28170429

Profiling of the Tox21 Chemical Collection for Mitochondrial Function: I. Compounds that Decrease Mitochondrial Membrane Potential

EPA Science Inventory

Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding how different environmental chemicals and drug-like molecules impact mitochondrial function rep...

MitProNet: A Knowledgebase and Analysis Platform of Proteome, Interactome and Diseases for Mammalian Mitochondria

PubMed Central

Mao, Song; Chai, Xiaoqiang; Hu, Yuling; Hou, Xugang; Tang, Yiheng; Bi, Cheng; Li, Xiao

2014-01-01

Mitochondrion plays a central role in diverse biological processes in most eukaryotes, and its dysfunctions are critically involved in a large number of diseases and the aging process. A systematic identification of mitochondrial proteomes and characterization of functional linkages among mitochondrial proteins are fundamental in understanding the mechanisms underlying biological functions and human diseases associated with mitochondria. Here we present a database MitProNet which provides a comprehensive knowledgebase for mitochondrial proteome, interactome and human diseases. First an inventory of mammalian mitochondrial proteins was compiled by widely collecting proteomic datasets, and the proteins were classified by machine learning to achieve a high-confidence list of mitochondrial proteins. The current version of MitProNet covers 1124 high-confidence proteins, and the remainders were further classified as middle- or low-confidence. An organelle-specific network of functional linkages among mitochondrial proteins was then generated by integrating genomic features encoded by a wide range of datasets including genomic context, gene expression profiles, protein-protein interactions, functional similarity and metabolic pathways. The functional-linkage network should be a valuable resource for the study of biological functions of mitochondrial proteins and human mitochondrial diseases. Furthermore, we utilized the network to predict candidate genes for mitochondrial diseases using prioritization algorithms. All proteins, functional linkages and disease candidate genes in MitProNet were annotated according to the information collected from their original sources including GO, GEO, OMIM, KEGG, MIPS, HPRD and so on. MitProNet features a user-friendly graphic visualization interface to present functional analysis of linkage networks. As an up-to-date database and analysis platform, MitProNet should be particularly helpful in comprehensive studies of complicated biological mechanisms underlying mitochondrial functions and human mitochondrial diseases. MitProNet is freely accessible at http://bio.scu.edu.cn:8085/MitProNet. PMID:25347823

Decreased Mitochondrial Pyruvate Transport Activity in the Diabetic Heart

PubMed Central

Vadvalkar, Shraddha S.; Matsuzaki, Satoshi; Eyster, Craig A.; Giorgione, Jennifer R.; Bockus, Lee B.; Kinter, Caroline S.; Kinter, Michael

2017-01-01

Alterations in mitochondrial function contribute to diabetic cardiomyopathy. We have previously shown that heart mitochondrial proteins are hyperacetylated in OVE26 mice, a transgenic model of type 1 diabetes. However, the universality of this modification and its functional consequences are not well established. In this study, we demonstrate that Akita type 1 diabetic mice exhibit hyperacetylation. Functionally, isolated Akita heart mitochondria have significantly impaired maximal (state 3) respiration with physiological pyruvate (0.1 mm) but not with 1.0 mm pyruvate. In contrast, pyruvate dehydrogenase activity is significantly decreased regardless of the pyruvate concentration. We found that there is a 70% decrease in the rate of pyruvate transport in Akita heart mitochondria but no decrease in the mitochondrial pyruvate carriers 1 and 2 (MPC1 and MPC2). The potential role of hyperacetylation in mediating this impaired pyruvate uptake was examined. The treatment of control mitochondria with the acetylating agent acetic anhydride inhibits pyruvate uptake and pyruvate-supported respiration in a similar manner to the pyruvate transport inhibitor α-cyano-4-hydroxycinnamate. A mass spectrometry selective reactive monitoring assay was developed and used to determine that acetylation of lysines 19 and 26 of MPC2 is enhanced in Akita heart mitochondria. Expression of a double acetylation mimic of MPC2 (K19Q/K26Q) in H9c2 cells was sufficient to decrease the maximal cellular oxygen consumption rate. This study supports the conclusion that deficient pyruvate transport activity, mediated in part by acetylation of MPC2, is a contributor to metabolic inflexibility in the diabetic heart. PMID:28154187

Epoxyeicosatrienoic Acids Regulate Adipocyte Differentiation of Mouse 3T3 Cells, Via PGC-1α Activation, Which Is Required for HO-1 Expression and Increased Mitochondrial Function

PubMed Central

Waldman, Maayan; Bellner, Lars; Vanella, Luca; Schragenheim, Joseph; Sodhi, Komal; Singh, Shailendra P.; Lin, Daohong; Lakhkar, Anand; Li, Jiangwei; Hochhauser, Edith; Arad, Michael; Darzynkiewicz, Zbigniew; Kappas, Atallah

2016-01-01

Epoxyeicosatrienoic acid (EET) contributes to browning of white adipose stem cells to ameliorate obesity/diabetes and insulin resistance. In the current study, we show that EET altered preadipocyte function, enhanced peroxisome proliferation-activated receptor γ coactivator α (PGC-1α) expression, and increased mitochondrial function in the 3T3-L1 preadipocyte subjected to adipogenesis. Cells treated with EET resulted in an increase, P < 0.05, in PGC-1α and a decrease in mitochondria-derived ROS (MitoSox), P < 0.05. The EET increase in heme oxygenase-1 (HO-1) levels is dependent on activation of PGC-1α as cells deficient in PGC-1α (PGC-1α knockout adipocyte cell) have an impaired ability to express HO-1, P < 0.02. Additionally, adipocytes treated with EET exhibited an increase in mitochondrial superoxide dismutase (SOD) in a PGC-1α-dependent manner, P < 0.05. The increase in PGC-1α was associated with an increase in β-catenin, P < 0.05, adiponectin expression, P < 0.05, and lipid accumulation, P < 0.02. EET decreased heme levels and mitochondria-derived ROS (MitoSox), P < 0.05, compared to adipocytes that were untreated. EET also decreased mesoderm-specific transcript (MEST) mRNA and protein levels (P < 0.05). Adipocyte secretion of EET act in an autocrine/paracrine manner to increase PGC-1α is required for activation of HO-1 expression. This is the first study to dissect the mechanism by which the antiadipogenic and anti-inflammatory lipid, EET, induces the PGC-1α signaling cascade and reprograms the adipocyte phenotype by regulating mitochondrial function and HO-1 expression, leading to an increase in healthy, that is, small, adipocytes and a decrease in adipocyte enlargement and terminal differentiation. This is manifested by an increase in mitochondrial function and an increase in the canonical Wnt signaling cascade during adipocyte proliferation and terminal differentiation. PMID:27224420

Psychological Stress and Mitochondria: A Systematic Review.

PubMed

Picard, Martin; McEwen, Bruce S

Mitochondria are multifunctional life-sustaining organelles that represent a potential intersection point between psychosocial experiences and biological stress responses. This article provides a systematic review of the effects of psychological stress on mitochondrial structure and function. A systematic review of the literature investigating the effects of psychological stress on mitochondrial function was conducted. The review focused on experimentally controlled studies allowing us to draw causal inference about the effect of induced psychological stress on mitochondria. A total of 23 studies met the inclusion criteria. All studies involved male laboratory animals, and most demonstrated that acute and chronic stressors influenced specific facets of mitochondrial function, particularly within the brain. Nineteen studies showed significant adverse effects of psychological stress on mitochondria and four found increases in function or size after stress. In humans, only six observational studies were available, none with experimental designs, and most only measured biological markers that do not directly reflect mitochondrial function, such as mitochondrial DNA copy number. Overall, evidence supports the notion that acute and chronic stressors influence various aspects of mitochondrial biology, and that chronic stress exposure can lead to molecular and functional recalibrations among mitochondria. Limitations of current animal and human studies are discussed. Maladaptive mitochondrial changes that characterize this subcellular state of stress are termed mitochondrial allostatic load. Prospective studies with sensitive measures of specific mitochondrial outcomes will be needed to establish the link between psychosocial stressors, emotional states, the resulting neuroendocrine and immune processes, and mitochondrial energetics relevant to mind-body research in humans.

Cytosolic Irradiation of Femtosecond Laser Induces Mitochondria-dependent Apoptosis-like Cell Death via Intrinsic Reactive Oxygen Cascades

PubMed Central

Yoon, Jonghee; Ryu, Seung-wook; Lee, Seunghee; Choi, Chulhee

2015-01-01

High-intensity femtosecond lasers have recently been used to irreversibly disrupt nanoscale structures, such as intracellular organelles, and to modify biological functions in a reversible manner: so-called nanosurgery and biophotomodulation. Femtosecond laser pulses above the threshold intensity sufficient for reversible biophotomodulation can cause irreversible changes in the irradiated cell, eventually leading to cell death. Here, we demonstrated that cytosolic irradiation with a femtosecond laser produced intrinsic cascades of reactive oxygen species (ROS), which led to rapid apoptosis-like cell death via a caspase and poly (ADP-ribose) polymerase 1 (PARP-1) signaling pathway. We further showed that cells with enhanced mitochondrial fusion activity are more resilient to laser-induced stress compared to those with enforced mitochondrial fission. Taken together, these findings provide fundamental insight into how optical stimulation intervenes in intrinsic cellular signaling pathways and functions. PMID:25648455

Cytosolic irradiation of femtosecond laser induces mitochondria-dependent apoptosis-like cell death via intrinsic reactive oxygen cascades.

PubMed

Yoon, Jonghee; Ryu, Seung-Wook; Lee, Seunghee; Choi, Chulhee

2015-02-04

High-intensity femtosecond lasers have recently been used to irreversibly disrupt nanoscale structures, such as intracellular organelles, and to modify biological functions in a reversible manner: so-called nanosurgery and biophotomodulation. Femtosecond laser pulses above the threshold intensity sufficient for reversible biophotomodulation can cause irreversible changes in the irradiated cell, eventually leading to cell death. Here, we demonstrated that cytosolic irradiation with a femtosecond laser produced intrinsic cascades of reactive oxygen species (ROS), which led to rapid apoptosis-like cell death via a caspase and poly (ADP-ribose) polymerase 1 (PARP-1) signaling pathway. We further showed that cells with enhanced mitochondrial fusion activity are more resilient to laser-induced stress compared to those with enforced mitochondrial fission. Taken together, these findings provide fundamental insight into how optical stimulation intervenes in intrinsic cellular signaling pathways and functions.

Each Monomer of the Dimeric Accessory Protein for Human Mitochondrial DNA Polymerase Has a Distinct Role in Conferring Processivity*

PubMed Central

Lee, Young-Sam; Lee, Sujin; Demeler, Borries; Molineux, Ian J.; Johnson, Kenneth A.; Yin, Y. Whitney

2010-01-01

The accessory protein polymerase (pol) γB of the human mitochondrial DNA polymerase stimulates the synthetic activity of the catalytic subunit. pol γB functions by both accelerating the polymerization rate and enhancing polymerase-DNA interaction, thereby distinguishing itself from the accessory subunits of other DNA polymerases. The molecular basis for the unique functions of human pol γB lies in its dimeric structure, where the pol γB monomer proximal to pol γA in the holoenzyme strengthens the interaction with DNA, and the distal pol γB monomer accelerates the reaction rate. We further show that human pol γB exhibits a catalytic subunit- and substrate DNA-dependent dimerization. By duplicating the monomeric pol γB of lower eukaryotes, the dimeric mammalian proteins confer additional processivity to the holoenzyme polymerase. PMID:19858216

Ketogenic diets, mitochondria, and neurological diseases

PubMed Central

Gano, Lindsey B.; Patel, Manisha; Rho, Jong M.

2014-01-01

The ketogenic diet (KD) is a broad-spectrum therapy for medically intractable epilepsy and is receiving growing attention as a potential treatment for neurological disorders arising in part from bioenergetic dysregulation. The high-fat/low-carbohydrate “classic KD”, as well as dietary variations such as the medium-chain triglyceride diet, the modified Atkins diet, the low-glycemic index treatment, and caloric restriction, enhance cellular metabolic and mitochondrial function. Hence, the broad neuroprotective properties of such therapies may stem from improved cellular metabolism. Data from clinical and preclinical studies indicate that these diets restrict glycolysis and increase fatty acid oxidation, actions which result in ketosis, replenishment of the TCA cycle (i.e., anaplerosis), restoration of neurotransmitter and ion channel function, and enhanced mitochondrial respiration. Further, there is mounting evidence that the KD and its variants can impact key signaling pathways that evolved to sense the energetic state of the cell, and that help maintain cellular homeostasis. These pathways, which include PPARs, AMP-activated kinase, mammalian target of rapamycin, and the sirtuins, have all been recently implicated in the neuroprotective effects of the KD. Further research in this area may lead to future therapeutic strategies aimed at mimicking the pleiotropic neuroprotective effects of the KD. PMID:24847102

Eicosapentaenoic acid and arachidonic acid differentially regulate adipogenesis, acquisition of a brite phenotype and mitochondrial function in primary human adipocytes.

PubMed

Fleckenstein-Elsen, Manuela; Dinnies, Daniela; Jelenik, Tomas; Roden, Michael; Romacho, Tania; Eckel, Jürgen

2016-09-01

n-3 and n-6 PUFAs have several opposing biological effects and influence white adipose tissue (WAT) function. The recent discovery of thermogenic UCP1-expressing brite adipocytes within WAT raised the question whether n-3 and n-6 PUFAs exert differential effects on brite adipocyte formation and mitochondrial function. Primary human preadipocytes were treated with n-3 PUFAs (eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) or n-6 PUFA (arachidonic acid, ARA) during differentiation, and adipogenesis, white and brite gene expression markers, mitochondrial content and function were analyzed at day 12 of differentiation. Adipogenesis was equally increased by n-3 and n-6 PUFAs. The n-6 PUFA ARA increased lipid droplet size and expression of the white-specific marker TCF21 while decreased mitochondrial protein expression and respiratory function. In contrast, EPA increased expression of the brown adipocyte-related genes UCP1 and CPT1B, and improved mitochondrial function of adipocytes. The opposing effects of EPA and ARA on gene expression and mitochondrial function were also observed in cells treated from day 8 to 12 of adipocyte differentiation. EPA promotes brite adipogenesis and improves parameters of mitochondrial function, such as increased expression of CPTB1, citrate synthase activity and higher maximal respiratory capacity, while ARA reduced mitochondrial spare respiratory capacity in vitro. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mitochondrial Ubiquitin Ligase in Cardiovascular Disorders.

PubMed

Yu, Tao; Zhang, Yinfeng; Li, Pei-Feng

2017-01-01

Mitochondrial dynamics play a critical role in cellular responses and physiological process. However, their dysregulation leads to a functional degradation, which results in a diverse array of common disorders, including cardiovascular disease. In this background, the mitochondrial ubiquitin ligase has been attracting substantial research interest in recent years. Mitochondrial ubiquitin ligase is localized in the mitochondrial outer membrane, where it plays an essential role in the regulation of mitochondrial dynamics and apoptosis. In this chapter, we provide a comprehensive overview of the functions of mitochondrial ubiquitin ligases identified hitherto, with a special focus on cardiovascular disorders.

Regulation of Mitochondrial Function and Cellular Energy Metabolism by Protein Kinase C-λ/ι: A Novel Mode of Balancing Pluripotency

PubMed Central

Mahato, Biraj; Home, Pratik; Rajendran, Ganeshkumar; Paul, Arindam; Saha, Biswarup; Ganguly, Avishek; Ray, Soma; Roy, Nairita; Swerdlow, Russell H.; Paul, Soumen

2014-01-01

Pluripotent stem cells (PSCs) contain functionally immature mitochondria and rely upon high rates of glycolysis for their energy requirements. Thus, altered mitochondrial function and promotion of aerobic glycolysis is key to maintain and induce pluripotency. However, signaling mechanisms that regulate mitochondrial function and reprogram metabolic preferences in self-renewing vs. differentiated PSC populations are poorly understood. Here, using murine embryonic stem cells (ESCs) as a model system, we demonstrate that atypical protein kinase C isoform, PKC lambda/iota (PKCλ/ι), is a key regulator of mitochondrial function in ESCs. Depletion of PKCλ/ι in ESCs maintains their pluripotent state as evident from germline offsprings. Interestingly, loss of PKCλ/ι in ESCs leads to impairment in mitochondrial maturation, organization and a metabolic shift toward glycolysis under differentiating condition. Our mechanistic analyses indicate that a PKCλ/ι-HIF1α-PGC1α axis regulates mitochondrial respiration and balances pluripotency in ESCs. We propose that PKCλ/ι could be a crucial regulator of mitochondrial function and energy metabolism in stem cells and other cellular contexts. PMID:25142417

Insulin stimulates mitochondrial fusion and function in cardiomyocytes via the Akt-mTOR-NFκB-Opa-1 signaling pathway.

PubMed

Parra, Valentina; Verdejo, Hugo E; Iglewski, Myriam; Del Campo, Andrea; Troncoso, Rodrigo; Jones, Deborah; Zhu, Yi; Kuzmicic, Jovan; Pennanen, Christian; Lopez-Crisosto, Camila; Jaña, Fabián; Ferreira, Jorge; Noguera, Eduard; Chiong, Mario; Bernlohr, David A; Klip, Amira; Hill, Joseph A; Rothermel, Beverly A; Abel, Evan Dale; Zorzano, Antonio; Lavandero, Sergio

2014-01-01

Insulin regulates heart metabolism through the regulation of insulin-stimulated glucose uptake. Studies have indicated that insulin can also regulate mitochondrial function. Relevant to this idea, mitochondrial function is impaired in diabetic individuals. Furthermore, the expression of Opa-1 and mitofusins, proteins of the mitochondrial fusion machinery, is dramatically altered in obese and insulin-resistant patients. Given the role of insulin in the control of cardiac energetics, the goal of this study was to investigate whether insulin affects mitochondrial dynamics in cardiomyocytes. Confocal microscopy and the mitochondrial dye MitoTracker Green were used to obtain three-dimensional images of the mitochondrial network in cardiomyocytes and L6 skeletal muscle cells in culture. Three hours of insulin treatment increased Opa-1 protein levels, promoted mitochondrial fusion, increased mitochondrial membrane potential, and elevated both intracellular ATP levels and oxygen consumption in cardiomyocytes in vitro and in vivo. Consequently, the silencing of Opa-1 or Mfn2 prevented all the metabolic effects triggered by insulin. We also provide evidence indicating that insulin increases mitochondrial function in cardiomyocytes through the Akt-mTOR-NFκB signaling pathway. These data demonstrate for the first time in our knowledge that insulin acutely regulates mitochondrial metabolism in cardiomyocytes through a mechanism that depends on increased mitochondrial fusion, Opa-1, and the Akt-mTOR-NFκB pathway.

Insulin Stimulates Mitochondrial Fusion and Function in Cardiomyocytes via the Akt-mTOR-NFκB-Opa-1 Signaling Pathway

PubMed Central

Parra, Valentina; Verdejo, Hugo E.; Iglewski, Myriam; del Campo, Andrea; Troncoso, Rodrigo; Jones, Deborah; Zhu, Yi; Kuzmicic, Jovan; Pennanen, Christian; Lopez‑Crisosto, Camila; Jaña, Fabián; Ferreira, Jorge; Noguera, Eduard; Chiong, Mario; Bernlohr, David A.; Klip, Amira; Hill, Joseph A.; Rothermel, Beverly A.; Abel, Evan Dale; Zorzano, Antonio; Lavandero, Sergio

2014-01-01

Insulin regulates heart metabolism through the regulation of insulin-stimulated glucose uptake. Studies have indicated that insulin can also regulate mitochondrial function. Relevant to this idea, mitochondrial function is impaired in diabetic individuals. Furthermore, the expression of Opa-1 and mitofusins, proteins of the mitochondrial fusion machinery, is dramatically altered in obese and insulin-resistant patients. Given the role of insulin in the control of cardiac energetics, the goal of this study was to investigate whether insulin affects mitochondrial dynamics in cardiomyocytes. Confocal microscopy and the mitochondrial dye MitoTracker Green were used to obtain three-dimensional images of the mitochondrial network in cardiomyocytes and L6 skeletal muscle cells in culture. Three hours of insulin treatment increased Opa-1 protein levels, promoted mitochondrial fusion, increased mitochondrial membrane potential, and elevated both intracellular ATP levels and oxygen consumption in cardiomyocytes in vitro and in vivo. Consequently, the silencing of Opa-1 or Mfn2 prevented all the metabolic effects triggered by insulin. We also provide evidence indicating that insulin increases mitochondrial function in cardiomyocytes through the Akt-mTOR-NFκB signaling pathway. These data demonstrate for the first time in our knowledge that insulin acutely regulates mitochondrial metabolism in cardiomyocytes through a mechanism that depends on increased mitochondrial fusion, Opa-1, and the Akt-mTOR-NFκB pathway. PMID:24009260

Normalization of CD4+ T Cell Metabolism Reverses Lupus

PubMed Central

Yin, Yiming; Choi, Seung-Chul; Xu, Zhiwei; Perry, Daniel J.; Seay, Howard; Croker, Byron P.; Sobel, Eric S.; Brusko, Todd M.; Morel, Laurence

2015-01-01

Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which autoreactive CD4+ T cells play an essential role. CD4+ T cells rely on glycolysis for inflammatory effector functions, but recent studies have shown that mitochondrial metabolism supports their chronic activation. How these processes contribute to lupus is unclear. Here, we show that both glycolysis and mitochondrial oxidative metabolism are elevated in CD4+ T cells from lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice as compared to non-autoimmune controls. In vitro, both the mitochondrial metabolism inhibitor metformin and the glucose metabolism inhibitor 2-Deoxy-D-glucose (2DG) reduced IFNγ production, although at different stages of activation. Metformin also restored the defective IL-2 production by TC CD4+ T cells. In vivo, treatment of TC mice and other lupus models with a combination of metformin and 2DG normalized T cell metabolism and reversed disease biomarkers. Further, CD4+ T cells from SLE patients also exhibited enhanced glycolysis and mitochondrial metabolism that correlated with their activation status, and their excessive IFNγ production was significantly reduced by metformin in vitro. These results suggest that normalization of T cell metabolism through the dual inhibition of glycolysis and mitochondrial metabolism is a promising therapeutic venue for SLE. PMID:25673763

Ubiquinol-10 supplementation activates mitochondria functions to decelerate senescence in senescence-accelerated mice.

PubMed

Tian, Geng; Sawashita, Jinko; Kubo, Hiroshi; Nishio, Shin-ya; Hashimoto, Shigenari; Suzuki, Nobuyoshi; Yoshimura, Hidekane; Tsuruoka, Mineko; Wang, Yaoyong; Liu, Yingye; Luo, Hongming; Xu, Zhe; Mori, Masayuki; Kitano, Mitsuaki; Hosoe, Kazunori; Takeda, Toshio; Usami, Shin-ichi; Higuchi, Keiichi

2014-06-01

The present study was conducted to define the relationship between the anti-aging effect of ubiquinol-10 supplementation and mitochondrial activation in senescence-accelerated mouse prone 1 (SAMP1) mice. Here, we report that dietary supplementation with ubiquinol-10 prevents age-related decreases in the expression of sirtuin gene family members, which results in the activation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a major factor that controls mitochondrial biogenesis and respiration, as well as superoxide dismutase 2 (SOD2) and isocitrate dehydrogenase 2 (IDH2), which are major mitochondrial antioxidant enzymes. Ubiquinol-10 supplementation can also increase mitochondrial complex I activity and decrease levels of oxidative stress markers, including protein carbonyls, apurinic/apyrimidinic sites, malondialdehydes, and increase the reduced glutathione/oxidized glutathione ratio. Furthermore, ubiquinol-10 may activate Sirt1 and PGC-1α by increasing cyclic adenosine monophosphate (cAMP) levels that, in turn, activate cAMP response element-binding protein (CREB) and AMP-activated protein kinase (AMPK). These results show that ubiquinol-10 may enhance mitochondrial activity by increasing levels of SIRT1, PGC-1α, and SIRT3 that slow the rate of age-related hearing loss and protect against the progression of aging and symptoms of age-related diseases.

In Vivo Microscopy Reveals Extensive Embedding of Capillaries within the Sarcolemma of Skeletal Muscle Fibers

PubMed Central

Glancy, Brian; Hsu, Li-Yueh; Dao, Lam; Bakalar, Matthew; French, Stephanie; Chess, David J.; Taylor, Joni L.; Picard, Martin; Aponte, Angel; Daniels, Mathew P.; Esfahani, Shervin; Cushman, Samuel; Balaban, Robert S.

2013-01-01

Objective To provide insight into mitochondrial function in vivo, we evaluated the 3D spatial relationship between capillaries, mitochondria, and muscle fibers in live mice. Methods 3D volumes of in vivo murine Tibialis anterior muscles were imaged by multi-photon microscopy (MPM). Muscle fiber type, mitochondrial distribution, number of capillaries, and capillary-to-fiber contact were assessed. The role of myoglobin-facilitated diffusion was examined in myoglobin knockout mice. Distribution of GLUT4 was also evaluated in the context of the capillary and mitochondrial network. Results MPM revealed that 43.6 ± 3.3% of oxidative fiber capillaries had ≥ 50% of their circumference embedded in a groove in the sarcolemma, in vivo. Embedded capillaries were tightly associated with dense mitochondrial populations lateral to capillary grooves and nearly absent below the groove. Mitochondrial distribution, number of embedded capillaries, and capillary-to-fiber contact were proportional to fiber oxidative capacity and unaffected by myoglobin knockout. GLUT4 did not preferentially localize to embedded capillaries. Conclusions Embedding capillaries in the sarcolemma may provide a regulatory mechanism to optimize delivery of oxygen to heterogeneous groups of muscle fibers. We hypothesize that mitochondria locate to paravascular regions due to myofibril voids created by embedded capillaries, not to enhance the delivery of oxygen to the mitochondria. PMID:25279425

Differential regulation of mitochondrial pyruvate carrier genes modulates respiratory capacity and stress tolerance in yeast.

PubMed

Timón-Gómez, Alba; Proft, Markus; Pascual-Ahuir, Amparo

2013-01-01

Mpc proteins are highly conserved from yeast to humans and are necessary for the uptake of pyruvate at the inner mitochondrial membrane, which is used for leucine and valine biosynthesis and as a fuel for respiration. Our analysis of the yeast MPC gene family suggests that amino acid biosynthesis, respiration rate and oxidative stress tolerance are regulated by changes in the Mpc protein composition of the mitochondria. Mpc2 and Mpc3 are highly similar but functionally different: Mpc2 is most abundant under fermentative non stress conditions and important for amino acid biosynthesis, while Mpc3 is the most abundant family member upon salt stress or when high respiration rates are required. Accordingly, expression of the MPC3 gene is highly activated upon NaCl stress or during the transition from fermentation to respiration, both types of regulation depend on the Hog1 MAP kinase. Overexpression experiments show that gain of Mpc2 function leads to a severe respiration defect and ROS accumulation, while Mpc3 stimulates respiration and enhances tolerance to oxidative stress. Our results identify the regulated mitochondrial pyruvate uptake as an important determinant of respiration rate and stress resistance.

Ketones prevent synaptic dysfunction induced by mitochondrial respiratory complex inhibitors

PubMed Central

Kim, Do Young; Vallejo, Johana; Rho, Jong M

2010-01-01

Abstract Ketones have previously shown beneficial effects in models of neurodegenerative disorders, particularly against associated mitochondrial dysfunction and cognitive impairment. However, evidence of a synaptic protective effect of ketones remains lacking. We tested the effects of ketones on synaptic impairment induced by mitochondrial respiratory complex (MRC) inhibitors using electrophysiological, reactive oxygen species (ROS) imaging and biochemical techniques. MRC inhibitors dose-dependently suppressed both population spike (PS) and field potential amplitudes in the CA1 hippocampus. Pre-treatment with ketones strongly prevented changes in the PS, whereas partial protection was seen in the field potential. Rotenone (Rot; 100 nmol/L), a MRC I inhibitor, suppressed synaptic function without altering ROS levels and PS depression by Rot was unaffected by antioxidants. In contrast, antioxidant-induced PS recovery against the MRC II inhibitor 3-nitropropionic acid (3-NP; 1 mmol/L) was similar to the synaptic protective effects of ketones. Ketones also suppressed ROS generation induced by 3-NP. Finally, ketones reversed the decreases in ATP levels caused by Rot and 3-NP. In summary, our data demonstrate that ketones can preserve synaptic function in CA1 hippocampus induced by MRC dysfunction, likely through an antioxidant action and enhanced ATP generation. PMID:20374433

Eicosapentaenoic acid but not docosahexaenoic acid restores skeletal muscle mitochondrial oxidative capacity in old mice.

PubMed

Johnson, Matthew L; Lalia, Antigoni Z; Dasari, Surendra; Pallauf, Maximilian; Fitch, Mark; Hellerstein, Marc K; Lanza, Ian R

2015-10-01

Mitochondrial dysfunction is often observed in aging skeletal muscle and is implicated in age-related declines in physical function. Early evidence suggests that dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve mitochondrial function. Here, we show that 10 weeks of dietary eicosapentaenoic acid (EPA) supplementation partially attenuated the age-related decline in mitochondrial function in mice, but this effect was not observed with docosahexaenoic acid (DHA). The improvement in mitochondrial function with EPA occurred in the absence of any changes in mitochondrial abundance or biogenesis, which was evaluated from RNA sequencing, large-scale proteomics, and direct measurements of muscle mitochondrial protein synthesis rates. We find that EPA improves muscle protein quality, specifically by decreasing mitochondrial protein carbamylation, a post-translational modification that is driven by inflammation. These results demonstrate that EPA attenuated the age-related loss of mitochondrial function and improved mitochondrial protein quality through a mechanism that is likely linked with anti-inflammatory properties of n-3 PUFAs. Furthermore, we demonstrate that EPA and DHA exert some common biological effects (anticoagulation, anti-inflammatory, reduced FXR/RXR activation), but also exhibit many distinct biological effects, a finding that underscores the importance of evaluating the therapeutic potential of individual n-3 PUFAs. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Loss of mitochondrial exo/endonuclease EXOG affects mitochondrial respiration and induces ROS-mediated cardiomyocyte hypertrophy.

PubMed

Tigchelaar, Wardit; Yu, Hongjuan; de Jong, Anne Margreet; van Gilst, Wiek H; van der Harst, Pim; Westenbrink, B Daan; de Boer, Rudolf A; Silljé, Herman H W

2015-01-15

Recently, a locus at the mitochondrial exo/endonuclease EXOG gene, which has been implicated in mitochondrial DNA repair, was associated with cardiac function. The function of EXOG in cardiomyocytes is still elusive. Here we investigated the role of EXOG in mitochondrial function and hypertrophy in cardiomyocytes. Depletion of EXOG in primary neonatal rat ventricular cardiomyocytes (NRVCs) induced a marked increase in cardiomyocyte hypertrophy. Depletion of EXOG, however, did not result in loss of mitochondrial DNA integrity. Although EXOG depletion did not induce fetal gene expression and common hypertrophy pathways were not activated, a clear increase in ribosomal S6 phosphorylation was observed, which readily explains increased protein synthesis. With the use of a Seahorse flux analyzer, it was shown that the mitochondrial oxidative consumption rate (OCR) was increased 2.4-fold in EXOG-depleted NRVCs. Moreover, ATP-linked OCR was 5.2-fold higher. This increase was not explained by mitochondrial biogenesis or alterations in mitochondrial membrane potential. Western blotting confirmed normal levels of the oxidative phosphorylation (OXPHOS) complexes. The increased OCR was accompanied by a 5.4-fold increase in mitochondrial ROS levels. These increased ROS levels could be normalized with specific mitochondrial ROS scavengers (MitoTEMPO, mnSOD). Remarkably, scavenging of excess ROS strongly attenuated the hypertrophic response. In conclusion, loss of EXOG affects normal mitochondrial function resulting in increased mitochondrial respiration, excess ROS production, and cardiomyocyte hypertrophy. Copyright © 2015 the American Physiological Society.

Calcineurin Regulates Myocardial Function during Acute Endotoxemia

PubMed Central

Joshi, Mandar S.; Julian, Mark W.; Huff, Jennifer E.; Bauer, John A.; Xia, Yong; Crouser, Elliott D.

2006-01-01

Rationale: Cyclosporin A (CsA) is known to preserve cardiac contractile function during endotoxemia, but the mechanism is unclear. Increased nitric oxide (NO) production and altered mitochondrial function are implicated as mechanisms contributing to sepsis-induced cardiac dysfunction, and CsA has the capacity to reduce NO production and inhibit mitochondrial dysfunction relating to the mitochondrial permeability transition (MPT). Objectives: We hypothesized that CsA would protect against endotoxin-mediated cardiac contractile dysfunction by attenuating NO production and preserving mitochondrial function. Methods: Left ventricular function was measured continuously over 4 h in cats assigned as follows: control animals (n = 7); LPS alone (3 mg/kg, n = 8); and CsA (6 mg/kg, n = 7), a calcineurin inhibitor that blocks the MPT, or tacrolimus (FK506, 0.1 mg/kg, n = 7), a calcineurin inhibitor lacking MPT activity, followed in 30 min by LPS. Myocardial tissue was then analyzed for NO synthase-2 expression, tissue nitration, protein carbonylation, and mitochondrial morphology and function. Measurements and Main Results: LPS treatment resulted in impaired left ventricular contractility, altered mitochondrial morphology and function, and increased protein nitration. As hypothesized, CsA pretreatment normalized cardiac performance and mitochondrial respiration and reduced myocardial protein nitration. Unexpectedly, FK506 pretreatment had similar effects, normalizing both cardiac and mitochondrial parameters. However, CsA and FK506 pretreatments markedly increased protein carbonylation in the myocardium despite elevated manganese superoxide dismutase activity during endotoxemia. Conclusions: Our data indicate that calcineurin is a critical regulator of mitochondrial respiration, tissue nitration, protein carbonylation, and contractile function in the heart during acute endotoxemia. PMID:16424445

Mitochondrial Ion Channels in Cancer Transformation

PubMed Central

Madamba, Stephen M.; Damri, Kevin N.; Dejean, Laurent M.; Peixoto, Pablo M.

2015-01-01

Cancer transformation involves reprograming of mitochondrial function to avert cell death mechanisms, monopolize energy metabolism, accelerate mitotic proliferation, and promote metastasis. Mitochondrial ion channels have emerged as promising therapeutic targets because of their connection to metabolic and apoptotic functions. This mini review discusses how mitochondrial channels may be associated with cancer transformation and expands on the possible involvement of mitochondrial protein import complexes in pathophysiological process. PMID:26090338

Physical exercise prevents cognitive impairment by enhancing hippocampal neuroplasticity and mitochondrial function in doxorubicin-induced chemobrain.

PubMed

Park, Hye-Sang; Kim, Chang-Ju; Kwak, Hyo-Bum; No, Mi-Hyun; Heo, Jun-Won; Kim, Tae-Woon

2018-05-01

Although chemotherapy increases the survival rate of patients with various cancers, such treatment can induce acute or long-term cognitive dysfunction a phenomenon known as post-chemotherapy cognitive impairment (PCCI) or "chemobrain." Exercise is known to positively affect brain function. Thus, the present study aimed to determine whether symptoms of chemobrain and disruptions in the neuroplasticity and functioning of hippocampal mitochondria can be prevented or relieved by exercise. Wistar rats were separated into the following groups: control, control plus exercise, chemobrain, and chemobrain plus exercise. For chemobrain induction, 2 mg/kg of doxorubicin (DOX) a widely utilized chemotherapeutic agent among patients with breast cancer was dissolved in saline and directly injected to the abdomen once every 4 weeks. The exercise groups were subjected to low-intensity treadmill, 6 days per week for 4 weeks. The Morris water maze and step-down avoidance tests were conducted to evaluate cognitive function, while neuroplasticity and mitochondrial function were assessed in the hippocampus and dentate gyrus. Decreased cognitive function were observed in the chemobrain group, along with decreases in levels of neurogenesis, brain derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB), Ca 2+ retention in hippocampus. Rats of the chemobrain group also exhibited an increase in apoptosis, H 2 O 2 emission and permeability transition pore by hippocampal mitochondria. However, exercise attenuated impairments in cognitive function, neuroplasticity, and mitochondrial function induced by DOX treatment. Therefore, the findings of the present study indicate that low-intensity exercise may assist in preventing cognitive dysfunction during or after chemotherapy in patients with various cancers, including breast cancer. Copyright © 2018 Elsevier Ltd. All rights reserved.

Uncoupling of oxidative phosphorylation and ATP synthase reversal within the hyperthermic heart.

PubMed

Power, Amelia; Pearson, Nicholas; Pham, Toan; Cheung, Carlos; Phillips, Anthony; Hickey, Anthony

2014-09-01

Heart failure is a common cause of death with hyperthermia, and the exact cause of hyperthermic heart failure appears elusive. We hypothesize that the energy supply (ATP) of the heart may become impaired due to increased inner-mitochondrial membrane permeability and inefficient oxidative phosphorylation (OXPHOS). Therefore, we assessed isolated working heart and mitochondrial function. Ex vivo working rat hearts were perfused between 37 and 43.5°C and showed break points in all functional parameters at ~40.5°C. Mitochondrial high-resolution respirometry coupled to fluorometry was employed to determine the effects of hyperthermia on OXPHOS and mitochondrial membrane potential (ΔΨ) in vitro using a comprehensive metabolic substrate complement with isolated mitochondria. Relative to 37 and 40°C, 43°C elevated Leak O2 flux and depressed OXPHOS O2 flux and ∆Ψ. Measurement of steady-state ATP production from mitochondria revealed decreased ATP synthesis capacity, and a negative steady-state P:O ratio at 43°C. This approach offers a more powerful analysis of the effects of temperature on OXPHOS that cannot be measured using simple measures such as the traditional respiratory control ratio (RCR) or P:O ratio, which, respectively, can only approach 1 or 0 with inner-membrane failure. At 40°C there was only a slight enhancement of the Leak O2 flux and this did not significantly affect ATP production rate. Therefore, during mild hyperthermia (40°C) there is no enhancement of ATP supply by mitochondria, to accompany increasing cardiac energy demands, while between this and critical hyperthermia (43°C), mitochondria become net consumers of ATP. This consumption may contribute to cardiac failure or permanent damage during severe hyperthermia. © 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Transcranial near-infrared photobiomodulation attenuates memory impairment and hippocampal oxidative stress in sleep-deprived mice.

PubMed

Salehpour, Farzad; Farajdokht, Fereshteh; Erfani, Marjan; Sadigh-Eteghad, Saeed; Shotorbani, Siamak Sandoghchian; Hamblin, Michael R; Karimi, Pouran; Rasta, Seyed Hossein; Mahmoudi, Javad

2018-03-01

Sleep deprivation (SD) causes oxidative stress in the hippocampus and subsequent memory impairment. In this study, the effect of near-infrared (NIR) photobiomodulation (PBM) on learning and memory impairment induced by acute SD was investigated. The mice were subjected to an acute SD protocol for 72 h. Simultaneously, NIR PBM using a laser at 810 nm was delivered (once a day for 3 days) transcranially to the head to affect the entire brain of mice. The Barnes maze and the What-Where-Which task were used to assess spatial and episodic-like memories. The hippocampal levels of antioxidant enzymes and oxidative stress biomarkers were evaluated. The results showed that NIR PBM prevented cognitive impairment induced by SD. Moreover, NIR PBM therapy enhanced the antioxidant status and increased mitochondrial activity in the hippocampus of SD mice. Our findings revealed that hippocampus-related mitochondrial damage and extensive oxidative stress contribute to the occurrence of memory impairment. In contrast, NIR PBM reduced hippocampal oxidative damage, supporting the ability of 810 nm laser light to improve the antioxidant defense system and maintain mitochondrial survival. This confirms that non-invasive transcranial NIR PBM therapy ameliorates hippocampal dysfunction, which is reflected in enhanced memory function. Copyright © 2018 Elsevier B.V. All rights reserved.

Multilayered control of peroxisomal activity upon salt stress in Saccharomyces cerevisiae.

PubMed

Manzanares-Estreder, Sara; Espí-Bardisa, Joan; Alarcón, Benito; Pascual-Ahuir, Amparo; Proft, Markus

2017-06-01

Peroxisomes are dynamic organelles and the sole location for fatty acid β-oxidation in yeast cells. Here, we report that peroxisomal function is crucial for the adaptation to salt stress, especially upon sugar limitation. Upon stress, multiple layers of control regulate the activity and the number of peroxisomes. Activated Hog1 MAP kinase triggers the induction of genes encoding enzymes for fatty acid activation, peroxisomal import and β-oxidation through the Adr1 transcriptional activator, which transiently associates with genes encoding fatty acid metabolic enzymes in a stress- and Hog1-dependent manner. Moreover, Na + and Li + stress increases the number of peroxisomes per cell in a Hog1-independent manner, which depends instead of the retrograde pathway and the dynamin related GTPases Dnm1 and Vps1. The strong activation of the Faa1 fatty acyl-CoA synthetase, which specifically localizes to lipid particles and peroxisomes, indicates that adaptation to salt stress requires the enhanced mobilization of fatty acids from internal lipid stores. Furthermore, the activation of mitochondrial respiration during stress depends on peroxisomes, mitochondrial acetyl-carnitine uptake is essential for salt resistance and the number of peroxisomes attached to the mitochondrial network increases during salt adaptation, which altogether indicates that stress-induced peroxisomal β-oxidation triggers enhanced respiration upon salt shock. © 2017 John Wiley & Sons Ltd.

Mitochondrial translocation of EGFR regulates mitochondria dynamics and promotes metastasis in NSCLC.

PubMed

Che, Ting-Fang; Lin, Ching-Wen; Wu, Yi-Ying; Chen, Yu-Ju; Han, Chia-Li; Chang, Yih-leong; Wu, Chen-Tu; Hsiao, Tzu-Hung; Hong, Tse-Ming; Yang, Pan-Chyr

2015-11-10

Dysfunction of the mitochondria is well-known for being associated with cancer progression. In the present study, we analyzed the mitochondria proteomics of lung cancer cell lines with different invasion abilities and found that EGFR is highly expressed in the mitochondria of highly invasive non-small-cell lung cancer (NSCLC) cells. EGF induces the mitochondrial translocation of EGFR; further, it leads to mitochondrial fission and redistribution in the lamellipodia, upregulates cellular ATP production, and enhances motility in vitro and in vivo. Moreover, EGFR can regulate mitochondrial dynamics by interacting with Mfn1 and disturbing Mfn1 polymerization. Overexpression of Mfn1 reverses the phenotypes resulting from EGFR mitochondrial translocation. We show that the mitochondrial EGFR expressions are higher in paired samples of the metastatic lymph node as compared with primary lung tumor and are inversely correlated with the overall survival in NSCLC patients. Therefore, our results demonstrate that besides the canonical role of EGFR as a receptor tyrosine, the mitochondrial translocation of EGFR may enhance cancer invasion and metastasis through regulating mitochondria dynamics.

Strenuous exercise induces mitochondrial damage in skeletal muscle of old mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sangho; Kim, Minjung; Lim, Wonchung

Strenuous exercise is known to cause excessive ROS generation and inflammation. However, the mechanisms responsible for the regulation of mitochondrial integrity in the senescent muscle during high-intensity exercise (HE) are not well studied. Here, we show that HE suppresses up-regulation of mitochondrial function despite increase in mitochondrial copy number, following excessive ROS production, proinflammatory cytokines and NFκB activation. Moreover, HE in the old group resulted in the decreasing of both fusion (Mfn2) and fission (Drp1) proteins that may contribute to alteration of mitochondrial morphology. This study suggests that strenuous exercise does not reverse age-related mitochondrial damage and dysfunction by themore » increased ROS and inflammation. - Highlights: • Effect of exercise on mitochondrial function of aged skeletal muscles was studied. • Strenuous exercise triggered excessive ROS production and inflammatory cytokines. • Strenuous exercise suppressed mitochondrial function in senescent muscle.« less

Exercise-stimulated FGF23 promotes exercise performance via controlling the excess reactive oxygen species production and enhancing mitochondrial function in skeletal muscle.

PubMed

Li, Dong-Jie; Fu, Hui; Zhao, Ting; Ni, Min; Shen, Fu-Ming

2016-05-01

Physical exercise induces many adaptive changes in skeletal muscle and the whole body and improves metabolic characteristics. Fibroblast growth-factor 23 (FGF23) is a unique member of the FGF family that acts as a hormone regulating phosphate metabolism, calcitriol concentration, and kidney functions. The role of FGF23 in exercise and skeletal muscle is largely unknown yet. C57BL/6J mice were exercised on a motor treadmill. Mice serum FGF23 levels; FGF23 mRNA expression in various organs including the liver, heart, skeletal muscle tissue, and thyroid; and FGF23 receptor Klotho mRNA expression were examined using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and immunoblotting, respectively, after a single bout of acute exercise (60min), exhaustive exercise, and chronic prolonged exercise (60min every day for one week). C57BL/6J mice were injected with recombinant FGF23 (100mg/kg, twice per day, i.p.) or vehicle control (saline) for 3days, and then the exercise performance, reactive oxygen species (ROS), H2O2 production, and mitochondrial functional biomarkers in muscle (gene expression of sirtuin 1, PPAR-δ, PGC-1α and mitochondrial transcription factor A [TFAM], and citrate synthase activity) were assayed. Three forms of exercise, acute exercise, exhaustive exercise, and chronic exercise, increased serum FGF23 levels. However, only chronic exercise upregulated FGF23 mRNA and protein expression in skeletal muscle. FGF23 mRNA expression in the heart, liver, and thyroid was not affected. FGF23 protein was mainly located in the cytoplasm in skeletal muscle tissue and the localization of FGF23 was not altered by exercise. Exogenous FGF23 treatment significantly extended the time to exhaustion and reduced the exercise-induced ROS and H2O2 production. FGF23 treatment increased the mRNA level of PPAR-δ and citrate synthase activity, but did not influence the mRNA expression of sirtuin 1, PGC-1α, and TFAM in skeletal muscle. These results demonstrate that exercise-stimulated FGF23 promotes exercise performance via controlling the excess ROS production and enhancing mitochondrial function in skeletal muscle, which reveals an entirely novel role of FGF23 in skeletal muscle. Copyright © 2016 Elsevier Inc. All rights reserved.

Hydroxytyrosol prevents diet-induced metabolic syndrome and attenuates mitochondrial abnormalities in obese mice.

PubMed

Cao, Ke; Xu, Jie; Zou, Xuan; Li, Yuan; Chen, Cong; Zheng, Adi; Li, Hao; Li, Hua; Szeto, Ignatius Man-Yau; Shi, Yujie; Long, Jiangang; Liu, Jiankang; Feng, Zhihui

2014-02-01

A Mediterranean diet rich in olive oil has profound influence on health outcomes including metabolic syndrome. However, the active compound and detailed mechanisms still remain unclear. Hydroxytyrosol (HT), a major polyphenolic compound in virgin olive oil, has received increased attention for its antioxidative activity and regulation of mitochondrial function. Here, we investigated whether HT is the active compound in olive oil exerting a protective effect against metabolic syndrome. In this study, we show that HT could prevent high-fat-diet (HFD)-induced obesity, hyperglycemia, hyperlipidemia, and insulin resistance in C57BL/6J mice after 17 weeks supplementation. Within liver and skeletal muscle tissues, HT could decrease HFD-induced lipid deposits through inhibition of the SREBP-1c/FAS pathway, ameliorate HFD-induced oxidative stress by enhancing antioxidant enzyme activities, normalize expression of mitochondrial complex subunits and mitochondrial fission marker Drp1, and eventually inhibit apoptosis activation. Moreover, in muscle tissue, the levels of mitochondrial carbonyl protein were decreased and mitochondrial complex activities were significantly improved by HT supplementation. In db/db mice, HT significantly decreased fasting glucose, similar to metformin. Notably, HT decreased serum lipid, at which metformin failed. Also, HT was more effective at decreasing the oxidation levels of lipids and proteins in both liver and muscle tissue. Similar to the results in the HFD model, HT decreased muscle mitochondrial carbonyl protein levels and improved mitochondrial complex activities in db/db mice. Our study links the olive oil component HT to diabetes and metabolic disease through changes that are not limited to decreases in oxidative stress, suggesting a potential pharmaceutical or clinical use of HT in metabolic syndrome treatment. Copyright © 2013 Elsevier Inc. All rights reserved.

Nuclear modifier MTO2 modulates the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae.

PubMed

He, Xiangyu; Zhu, Xiaoyu; Wang, Xuexiang; Wang, Wei; Dai, Yu; Yan, Qingfeng

2013-01-01

The phenotypic manifestations of mitochondrial DNA (mtDNA) mutations are modulated by mitochondrial DNA haplotypes, nuclear modifier genes and environmental factors. The yeast mitochondrial 15S rRNA C1477G (P(R) or P(R) 454) mutation corresponds to the human 12S rRNA C1494T and A1555G mutations, which are well known as primary factors for aminoglycoside-induced nonsyndromic deafness. Here we report that the deletion of the nuclear modifier gene MTO2 suppressed the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae. First, the strain with a single mtDNA C1477G mutation exhibited hypersensitivity to neomycin. Functional assays indicated that the steady-state transcription level of mitochondrial DNA, the mitochondrial respiratory rate, and the membrane potential decreased significantly after neomycin treatment. The impaired mitochondria could not produce sufficient energy to maintain cell viability. Second, when the mto2 null and the mitochondrial C1477G mutations co-existed (mto2(P(R))), the oxygen consumption rate in the double mutant decreased markedly compared to that of the control strains (MTO2(P(S)), mto2(P(S)) and MTO2(P(R))). The expression levels of the key glycolytic genes HXK2, PFK1 and PYK1 in the mto2(P(R)) strain were stimulated by neomycin and up-regulated by 89%, 112% and 55%, respectively. The enhanced glycolysis compensated for the respiratory energy deficits, and could be inhibited by the glycolytic enzyme inhibitor. Our findings in yeast will provide a new insight into the pathogenesis of human deafness.

Post onset, oral rapamycin treatment delays development of mitochondrial encephalopathy only at supramaximal doses.

PubMed

Felici, Roberta; Buonvicino, Daniela; Muzzi, Mirko; Cavone, Leonardo; Guasti, Daniele; Lapucci, Andrea; Pratesi, Sara; De Cesaris, Francesco; Luceri, Francesca; Chiarugi, Alberto

2017-05-01

Mitochondrial encephalopathies are fatal, infantile neurodegenerative disorders caused by a deficit of mitochondrial functioning, for which there is urgent need to identify efficacious pharmacological treatments. Recent evidence shows that rapamycin administered both intraperitoneally or in the diet delays disease onset and enhances survival in the Ndufs4 null mouse model of mitochondrial encephalopathy. To delineate the clinical translatability of rapamycin in treatment of mitochondrial encephalopathy, we evaluated the drug's effects on disease evolution and mitochondrial parameters adopting treatment paradigms with fixed daily, oral doses starting at symptom onset in Ndufs4 knockout mice. Molecular mechanisms responsible for the pharmacodynamic effects of rapamycin were also evaluated. We found that rapamycin did not affect disease development at clinically-relevant doses (0.5 mg kg -1 ). Conversely, an oral dose previously adopted for intraperitoneal administration (8 mg kg -1 ) delayed development of neurological symptoms and increased median survival by 25%. Neurological improvement and lifespan were not further increased when the dose raised to 20 mg kg -1 . Notably, rapamycin at 8 mg kg -1 did not affect the reduced expression of respiratory complex subunits, as well as mitochondrial number and mtDNA content. This treatment regimen however significantly ameliorated architecture of mitochondria cristae in motor cortex and cerebellum. However, reduction of mTOR activity by rapamycin was not consistently found within the brain of knockout mice. Overall, data show the ability of rapamycin to improve ultrastructure of dysfunctional mitochondria and corroborate its therapeutic potential in mitochondrial disorders. The non-clinical standard doses required, however, raise concerns about its rapid and safe clinical transferability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exercise training improves vascular mitochondrial function

PubMed Central

Park, Song-Young; Rossman, Matthew J.; Gifford, Jayson R.; Bharath, Leena P.; Bauersachs, Johann; Richardson, Russell S.; Abel, E. Dale; Symons, J. David

2016-01-01

Exercise training is recognized to improve cardiac and skeletal muscle mitochondrial respiratory capacity; however, the impact of chronic exercise on vascular mitochondrial respiratory function is unknown. We hypothesized that exercise training concomitantly increases both vascular mitochondrial respiratory capacity and vascular function. Arteries from both sedentary (SED) and swim-trained (EX, 5 wk) mice were compared in terms of mitochondrial respiratory function, mitochondrial content, markers of mitochondrial biogenesis, redox balance, nitric oxide (NO) signaling, and vessel function. Mitochondrial complex I and complex I + II state 3 respiration and the respiratory control ratio (complex I + II state 3 respiration/complex I state 2 respiration) were greater in vessels from EX relative to SED mice, despite similar levels of arterial citrate synthase activity and mitochondrial DNA content. Furthermore, compared with the SED mice, arteries from EX mice displayed elevated transcript levels of peroxisome proliferative activated receptor-γ coactivator-1α and the downstream targets cytochrome c oxidase subunit IV isoform 1, isocitrate dehydrogenase (Idh) 2, and Idh3a, increased manganese superoxide dismutase protein expression, increased endothelial NO synthase phosphorylation (Ser1177), and suppressed reactive oxygen species generation (all P < 0.05). Although there were no differences in EX and SED mice concerning endothelium-dependent and endothelium-independent vasorelaxation, phenylephrine-induced vasocontraction was blunted in vessels from EX compared with SED mice, and this effect was normalized by NOS inhibition. These training-induced increases in vascular mitochondrial respiratory capacity and evidence of improved redox balance, which may, at least in part, be attributable to elevated NO bioavailability, have the potential to protect against age- and disease-related challenges to arterial function. PMID:26825520

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1

PubMed Central

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Background: Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. Methods: The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Results: Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (CcO), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 (P<0.05). Conclusion: The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression. PMID:27830025

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1.

PubMed

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (C c O), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 ( P <0.05). The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression.

Vulnerable Parkin Loss-of-Function Drosophila Dopaminergic Neurons Have Advanced Mitochondrial Aging, Mitochondrial Network Loss and Transiently Reduced Autophagosome Recruitment.

PubMed

Cackovic, Juliana; Gutierrez-Luke, Susana; Call, Gerald B; Juba, Amber; O'Brien, Stephanie; Jun, Charles H; Buhlman, Lori M

2018-01-01

Selective degeneration of substantia nigra dopaminergic (DA) neurons is a hallmark pathology of familial Parkinson's disease (PD). While the mechanism of degeneration is elusive, abnormalities in mitochondrial function and turnover are strongly implicated. An Autosomal Recessive-Juvenile Parkinsonism (AR-JP) Drosophila melanogaster model exhibits DA neurodegeneration as well as aberrant mitochondrial dynamics and function. Disruptions in mitophagy have been observed in parkin loss-of-function models, and changes in mitochondrial respiration have been reported in patient fibroblasts. Whether loss of parkin causes selective DA neurodegeneration in vivo as a result of lost or decreased mitophagy is unknown. This study employs the use of fluorescent constructs expressed in Drosophila DA neurons that are functionally homologous to those of the mammalian substantia nigra. We provide evidence that degenerating DA neurons in parkin loss-of-function mutant flies have advanced mitochondrial aging, and that mitochondrial networks are fragmented and contain swollen organelles. We also found that mitophagy initiation is decreased in park ( Drosophila parkin/PARK2 ortholog) homozygous mutants, but autophagosome formation is unaffected, and mitochondrial network volumes are decreased. As the fly ages, autophagosome recruitment becomes similar to control, while mitochondria continue to show signs of damage, and climbing deficits persist. Interestingly, aberrant mitochondrial morphology, aging and mitophagy initiation were not observed in DA neurons that do not degenerate. Our results suggest that parkin is important for mitochondrial homeostasis in vulnerable Drosophila DA neurons, and that loss of parkin-mediated mitophagy may play a role in degeneration of relevant DA neurons or motor deficits in this model.

Yeast mitochondria: an overview of mitochondrial biology and the potential of mitochondrial systems biology.

PubMed

Malina, Carl; Larsson, Christer; Nielsen, Jens

2018-08-01

Mitochondria are dynamic organelles of endosymbiotic origin that are essential components of eukaryal cells. They contain their own genetic machinery, have multicopy genomes and like their bacterial ancestors they consist of two membranes. However, the majority of the ancestral genome has been lost or transferred to the nuclear genome of the host, preserving only a core set of genes involved in oxidative phosphorylation. Mitochondria perform numerous biological tasks ranging from bioenergetics to production of protein co-factors, including heme and iron-sulfur clusters. Due to the importance of mitochondria in many cellular processes, mitochondrial dysfunction is implicated in a wide variety of human disorders. Much of our current knowledge on mitochondrial function and dysfunction comes from studies using Saccharomyces cerevisiae. This yeast has good fermenting capacity, rendering tolerance to mutations that inactivate oxidative phosphorylation and complete loss of mitochondrial DNA. Here, we review yeast mitochondrial metabolism and function with focus on S. cerevisiae and its contribution in understanding mitochondrial biology. We further review how systems biology studies, including mathematical modeling, has allowed gaining new insight into mitochondrial function, and argue that this approach may enable us to gain a holistic view on how mitochondrial function interacts with different cellular processes.

Cyclophilin D is required for mitochondrial removal by autophagy in cardiac cells

PubMed Central

Carreira, Raquel S.; Lee, Youngil; Ghochani, Mariam; Gustafsson, Åsa B.; Gottlieb, Roberta A.

2013-01-01

Autophagy is a highly regulated intracellular degradation process by which cells remove cytosolic long-lived proteins and damaged organelles. The mitochondrial permeability transition (MPT) results in mitochondrial depolarization and increased reactive oxygen species production, which can trigger autophagy. Therefore, we hypothesized that the MPT may have a role in signaling autophagy in cardiac cells. Mitochondrial membrane potential was lower in HL-1 cells subjected to starvation compared to cells maintained in full medium. Mitochondrial membrane potential was preserved in starved cells treated with cyclosporin A (CsA), suggesting the MPT pore is associated with starvation-induced depolarization. Starvation-induced autophagy in HL-1 cells, neonatal rat cardiomyocytes and adult mouse cardiomyocytes was inhibited by CsA. Starvation failed to induce autophagy in CypD-deficient murine cardiomyocytes, whereas in myocytes from mice overexpressing CypD the levels of autophagy were enhanced even under fed conditions. Collectively, these results demonstrate a role for CypD and the MPT in the initiation of autophagy. We also analyzed the role of the MPT in the degradation of mitochondria by biochemical analysis and electron microscopy. HL-1 cells subjected to starvation in the presence of CsA had higher levels of mitochondrial proteins (by Western blot), more mitochondria and less autophagosomes (by electron microscopy) then cells starved in the absence of CsA. Our results suggest a physiologic function for CypD and the MPT in the regulation of starvation-induced autophagy. Starvation-induced autophagy regulated by CypD and the MPT may represent a homeostatic mechanism for cellular and mitochondrial quality control. PMID:20364102

What Is Mitochondrial Disease?

MedlinePlus

... Review Mitochondrial Structure, Function and Diseases Review Cell Biology of Diagnosis and Treatment of Mitochondrial Diseases Review ... Factories and Much More The conventional teaching in biology and medicine is that mitochondria function only as “ ...

Mitochondrial Dynamics: Coupling Mitochondrial Fitness with Healthy Aging.

PubMed

Sebastián, David; Palacín, Manuel; Zorzano, Antonio

2017-03-01

Aging is associated with a decline in mitochondrial function and the accumulation of abnormal mitochondria. However, the precise mechanisms by which aging promotes these mitochondrial alterations and the role of the latter in aging are still not fully understood. Mitochondrial dynamics is a key process regulating mitochondrial function and quality. Altered expression of some mitochondrial dynamics proteins has been recently associated with aging and with age-related alterations in yeast, Caenorhabditis elegans, mice, and humans. Here, we review the link between alterations in mitochondrial dynamics, aging, and age-related impairment. We propose that the dysregulation of mitochondrial dynamics leads to age-induced accumulation of unhealthy mitochondria and contributes to alterations linked to aging, such as diabetes and neurodegeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lower Intrinsic ADP-Stimulated Mitochondrial Respiration Underlies In Vivo Mitochondrial Dysfunction in Muscle of Male Type 2 Diabetic Patients

PubMed Central

Phielix, Esther; Schrauwen-Hinderling, Vera B.; Mensink, Marco; Lenaers, Ellen; Meex, Ruth; Hoeks, Joris; Kooi, Marianne Eline; Moonen-Kornips, Esther; Sels, Jean-Pierre; Hesselink, Matthijs K.C.; Schrauwen, Patrick

2008-01-01

OBJECTIVE—A lower in vivo mitochondrial function has been reported in both type 2 diabetic patients and first-degree relatives of type 2 diabetic patients. The nature of this reduction is unknown. Here, we tested the hypothesis that a lower intrinsic mitochondrial respiratory capacity may underlie lower in vivo mitochondrial function observed in diabetic patients. RESEARCH DESIGN AND METHODS—Ten overweight diabetic patients, 12 first-degree relatives, and 16 control subjects, all men, matched for age and BMI, participated in this study. Insulin sensitivity was measured with a hyperinsulinemic-euglycemic clamp. Ex vivo intrinsic mitochondrial respiratory capacity was determined in permeabilized skinned muscle fibers using high-resolution respirometry and normalized for mitochondrial content. In vivo mitochondrial function was determined by measuring phosphocreatine recovery half-time after exercise using 31P-magnetic resonance spectroscopy. RESULTS—Insulin-stimulated glucose disposal was lower in diabetic patients compared with control subjects (11.2 ± 2.8 vs. 28.9 ± 3.7 μmol · kg−1 fat-free mass · min−1, respectively; P = 0.003), with intermediate values for first-degree relatives (22.1 ± 3.4 μmol · kg−1 fat-free mass · min−1). In vivo mitochondrial function was 25% lower in diabetic patients (P = 0.034) and 23% lower in first-degree relatives, but the latter did not reach statistical significance (P = 0.08). Interestingly, ADP-stimulated basal respiration was 35% lower in diabetic patients (P = 0.031), and fluoro-carbonyl cyanide phenylhydrazone–driven maximal mitochondrial respiratory capacity was 31% lower in diabetic patients (P = 0.05) compared with control subjects with intermediate values for first-degree relatives. CONCLUSIONS—A reduced basal ADP-stimulated and maximal mitochondrial respiratory capacity underlies the reduction in in vivo mitochondrial function, independent of mitochondrial content. A reduced capacity at both the level of the electron transport chain and phosphorylation system underlies this impaired mitochondrial capacity. PMID:18678616

A creatine-driven substrate cycle enhances energy expenditure and thermogenesis in beige fat.

PubMed

Kazak, Lawrence; Chouchani, Edward T; Jedrychowski, Mark P; Erickson, Brian K; Shinoda, Kosaku; Cohen, Paul; Vetrivelan, Ramalingam; Lu, Gina Z; Laznik-Bogoslavski, Dina; Hasenfuss, Sebastian C; Kajimura, Shingo; Gygi, Steve P; Spiegelman, Bruce M

2015-10-22

Thermogenic brown and beige adipose tissues dissipate chemical energy as heat, and their thermogenic activities can combat obesity and diabetes. Herein the functional adaptations to cold of brown and beige adipose depots are examined using quantitative mitochondrial proteomics. We identify arginine/creatine metabolism as a beige adipose signature and demonstrate that creatine enhances respiration in beige-fat mitochondria when ADP is limiting. In murine beige fat, cold exposure stimulates mitochondrial creatine kinase activity and induces coordinated expression of genes associated with creatine metabolism. Pharmacological reduction of creatine levels decreases whole-body energy expenditure after administration of a β3-agonist and reduces beige and brown adipose metabolic rate. Genes of creatine metabolism are compensatorily induced when UCP1-dependent thermogenesis is ablated, and creatine reduction in Ucp1-deficient mice reduces core body temperature. These findings link a futile cycle of creatine metabolism to adipose tissue energy expenditure and thermal homeostasis. PAPERCLIP. Copyright © 2015 Elsevier Inc. All rights reserved.

Altered mitochondrial function and oxidative stress in leukocytes of anorexia nervosa patients.

PubMed

Victor, Victor M; Rovira-Llopis, Susana; Saiz-Alarcon, Vanessa; Sangüesa, Maria C; Rojo-Bofill, Luis; Bañuls, Celia; Falcón, Rosa; Castelló, Raquel; Rojo, Luis; Rocha, Milagros; Hernández-Mijares, Antonio

2014-01-01

Anorexia nervosa is a common illness among adolescents and is characterised by oxidative stress. The effects of anorexia on mitochondrial function and redox state in leukocytes from anorexic subjects were evaluated. A multi-centre, cross-sectional case-control study was performed. Our study population consisted of 20 anorexic patients and 20 age-matched controls, all of which were Caucasian women. Anthropometric and metabolic parameters were evaluated in the study population. To assess whether anorexia nervosa affects mitochondrial function and redox state in leukocytes of anorexic patients, we measured mitochondrial oxygen consumption, membrane potential, reactive oxygen species production, glutathione levels, mitochondrial mass, and complex I and III activity in polymorphonuclear cells. Mitochondrial function was impaired in the leukocytes of the anorexic patients. This was evident in a decrease in mitochondrial O2 consumption (P<0.05), mitochondrial membrane potential (P<0.01) and GSH levels (P<0.05), and an increase in ROS production (P<0.05) with respect to control subjects. Furthermore, a reduction of mitochondrial mass was detected in leukocytes of the anorexic patients (P<0.05), while the activity of mitochondrial complex I (P<0.001), but not that of complex III, was found to be inhibited in the same population. Oxidative stress is produced in the leukocytes of anorexic patients and is closely related to mitochondrial dysfunction. Our results lead us to propose that the oxidative stress that occurs in anorexia takes place at mitochondrial complex I. Future research concerning mitochondrial dysfunction and oxidative stress should aim to determine the physiological mechanism involved in this effect and the physiological impact of anorexia.

Impaired complex IV activity in response to loss of LRPPRC function can be compensated by mitochondrial hyperfusion

PubMed Central

Rolland, Stéphane G.; Motori, Elisa; Memar, Nadin; Hench, Jürgen; Frank, Stephan; Winklhofer, Konstanze F.; Conradt, Barbara

2013-01-01

Mitochondrial morphology changes in response to various stimuli but the significance of this is unclear. In a screen for mutants with abnormal mitochondrial morphology, we identified MMA-1, the Caenorhabditis elegans homolog of the French Canadian Leigh Syndrome protein LRPPRC (leucine-rich pentatricopeptide repeat containing). We demonstrate that reducing mma-1 or LRPPRC function causes mitochondrial hyperfusion. Reducing mma-1/LRPPRC function also decreases the activity of complex IV of the electron transport chain, however without affecting cellular ATP levels. Preventing mitochondrial hyperfusion in mma-1 animals causes larval arrest and embryonic lethality. Furthermore, prolonged LRPPRC knock-down in mammalian cells leads to mitochondrial fragmentation and decreased levels of ATP. These findings indicate that in a mma-1/LRPPRC–deficient background, hyperfusion allows mitochondria to maintain their functions despite a reduction in complex IV activity. Our data reveal an evolutionary conserved mechanism that is triggered by reduced complex IV function and that induces mitochondrial hyperfusion to transiently compensate for a drop in the activity of the electron transport chain. PMID:23878239

OXPHOS-Dependent Cells Identify Environmental Disruptors of Mitochondrial Function

EPA Science Inventory

Mitochondrial dysfunction is associated with numerous chronic diseases including metabolic syndrome. Environmental chemicals can impair mitochondrial function through numerous mechanisms such as membrane disruption, complex inhibition and electron transport chain uncoupling. Curr...

Regulation of mitochondrial function and cellular energy metabolism by protein kinase C-λ/ι: a novel mode of balancing pluripotency.

PubMed

Mahato, Biraj; Home, Pratik; Rajendran, Ganeshkumar; Paul, Arindam; Saha, Biswarup; Ganguly, Avishek; Ray, Soma; Roy, Nairita; Swerdlow, Russell H; Paul, Soumen

2014-11-01

Pluripotent stem cells (PSCs) contain functionally immature mitochondria and rely upon high rates of glycolysis for their energy requirements. Thus, altered mitochondrial function and promotion of aerobic glycolysis are key to maintain and induce pluripotency. However, signaling mechanisms that regulate mitochondrial function and reprogram metabolic preferences in self-renewing versus differentiated PSC populations are poorly understood. Here, using murine embryonic stem cells (ESCs) as a model system, we demonstrate that atypical protein kinase C isoform, PKC lambda/iota (PKCλ/ι), is a key regulator of mitochondrial function in ESCs. Depletion of PKCλ/ι in ESCs maintains their pluripotent state as evident from germline offsprings. Interestingly, loss of PKCλ/ι in ESCs leads to impairment in mitochondrial maturation, organization, and a metabolic shift toward glycolysis under differentiating condition. Our mechanistic analyses indicate that a PKCλ/ι-hypoxia-inducible factor 1α-PGC1α axis regulates mitochondrial respiration and balances pluripotency in ESCs. We propose that PKCλ/ι could be a crucial regulator of mitochondrial function and energy metabolism in stem cells and other cellular contexts. © 2014 AlphaMed Press.

4-Methylene-2-octyl-5-oxotetrahydrofuran-3-carboxylic Acid (C75), an Inhibitor of Fatty-acid Synthase, Suppresses the Mitochondrial Fatty Acid Synthesis Pathway and Impairs Mitochondrial Function*

PubMed Central

Chen, Cong; Han, Xiao; Zou, Xuan; Li, Yuan; Yang, Liang; Cao, Ke; Xu, Jie; Long, Jiangang; Liu, Jiankang; Feng, Zhihui

2014-01-01

4-Methylene-2-octyl-5-oxotetrahydrofuran-3-carboxylic acid (C75) is a synthetic fatty-acid synthase (FASN) inhibitor with potential therapeutic effects in several cancer models. Human mitochondrial β-ketoacyl-acyl carrier protein synthase (HsmtKAS) is a key enzyme in the newly discovered mitochondrial fatty acid synthesis pathway that can produce the substrate for lipoic acid (LA) synthesis. HsmtKAS shares conserved catalytic domains with FASN, which are responsible for binding to C75. In our study, we explored the possible effect of C75 on HsmtKAS and mitochondrial function. C75 treatment decreased LA content, impaired mitochondrial function, increased reactive oxygen species content, and reduced cell viability. HsmtKAS but not FASN knockdown had an effect that was similar to C75 treatment. In addition, an LA supplement efficiently inhibited C75-induced mitochondrial dysfunction and oxidative stress. Overexpression of HsmtKAS showed cellular protection against low dose C75 addition, whereas there was no protective effect upon high dose C75 addition. In summary, the mitochondrial fatty acid synthesis pathway has a vital role in mitochondrial function. Besides FASN, C75 might also inhibit HsmtKAS, thereby reducing LA production, impairing mitochondrial function, and potentially having toxic effects. LA supplements sufficiently ameliorated the toxicity of C75, showing that a combination of C75 and LA may be a reliable cancer treatment. PMID:24784139

BAX inhibitor-1 is a Ca2+ channel critically important for immune cell function and survival

PubMed Central

Lisak, D; Schacht, T; Gawlitza, A; Albrecht, P; Aktas, O; Koop, B; Gliem, M; Hofstetter, H H; Zanger, K; Bultynck, G; Parys, J B; De Smedt, H; Kindler, T; Adams-Quack, P; Hahn, M; Waisman, A; Reed, J C; Hövelmeyer, N; Methner, A

2016-01-01

The endoplasmic reticulum (ER) serves as the major intracellular Ca2+ store and has a role in the synthesis and folding of proteins. BAX (BCL2-associated X protein) inhibitor-1 (BI-1) is a Ca2+ leak channel also implicated in the response against protein misfolding, thereby connecting the Ca2+ store and protein-folding functions of the ER. We found that BI-1-deficient mice suffer from leukopenia and erythrocytosis, have an increased number of splenic marginal zone B cells and higher abundance and nuclear translocation of NF-κB (nuclear factor-κ light-chain enhancer of activated B cells) proteins, correlating with increased cytosolic and ER Ca2+ levels. When put into culture, purified knockout T cells and even more so B cells die spontaneously. This is preceded by increased activity of the mitochondrial initiator caspase-9 and correlated with a significant surge in mitochondrial Ca2+ levels, suggesting an exhausted mitochondrial Ca2+ buffer capacity as the underlying cause for cell death in vitro. In vivo, T-cell-dependent experimental autoimmune encephalomyelitis and B-cell-dependent antibody production are attenuated, corroborating the ex vivo results. These results suggest that BI-1 has a major role in the functioning of the adaptive immune system by regulating intracellular Ca2+ homeostasis in lymphocytes. PMID:26470731

Design and rationale of a 16-week adjunctive randomized placebo-controlled trial of mitochondrial agents for the treatment of bipolar depression.

PubMed

Dean, Olivia M; Turner, Alyna; Malhi, Gin S; Ng, Chee; Cotton, Sue M; Dodd, Seetal; Sarris, Jerome; Samuni, Yuval; Tanious, Michelle; Dowling, Nathan; Waterdrinker, Astrid; Smith, Deidre; Berk, Michael

2015-01-01

Bipolar disorder places a significant burden on individuals, caregivers and family, and the broader community. Current treatments are believed to be more effective against manic symptoms, leaving a shortfall in recovery during the depressive phase of the illness. The current study draws on recent evidence suggesting that, in addition to increased oxidative load, alterations in mitochondrial function occur in bipolar disorder. This 16-week study aims to explore the potential benefits of N-acetylcysteine (NAC) alone or in combination (CT) with selected nutraceuticals believed to enhance mitochondrial function. The study includes adults diagnosed with bipolar disorder currently experiencing an episode of depression. Participants are asked to take NAC, CT, or placebo in addition to any usual treatments. A post-discontinuation visit is conducted 4 weeks following the treatment phase. The primary outcome of the study will be mean change on the Montgomery-Asberg Depression Rating Scale. Secondary outcomes include functioning, substance use, mania ratings, and quality of life. Blood samples will be collected at baseline and week 16 to explore biochemical alterations following treatment. This study may provide a novel adjunctive treatment for bipolar depression. Analysis of biological samples may assist in understanding the therapeutic benefits and the underlying etiology of bipolar depression. Australian and New Zealand Clinical Trial Registry ACTRN12612000830897.

Flow cytometric evaluation of antibiotic effects on viability and mitochondrial function of refrigerated spermatozoa of Nile tilapia

USGS Publications Warehouse

Segovia, M.; Jenkins, J.A.; Paniagua-Chavez, C.; Tiersch, T.R.

2000-01-01

Improved techniques for storage and evaluation of fish sperm would enhance breeding programs around the world. The goal of this study was to test the effect of antibiotics on refrigerated sperm from Nile tilapia (Oreochromis niloticus) by use of flow cytometry with 2 dual-staining protocols for objective assessment of sperm quality. Concentrations of 1 x 109 sperm/mL were suspended in Ringer's buffer at 318 mOsmol/kg (pH 8.0). The fluorescent stains Sybr 14 (10 ??M), propidium iodide (2.4 mM), and rhodamine 123 (0.13 ??M) were used to assess cell viability and mitochondrial function. Three concentrations of ampicillin, gentamicin, and an antibiotic/antimycotic solution were added to fresh spermatozoa. Motility estimates and flow cytometry measurements were made daily during 7 d of refrigerated storage (4 ??C). The highest concentrations of gentamicin and antibiotic/antimycotic and all 3 concentrations of ampicillin significantly reduced sperm viability. The highest of each of the 3 antibiotic concentrations significantly reduced mitochondrial function. This study demonstrates that objective sperm quality assessments can be made using flow cytometry and that addition of antibiotics at appropriate concentrations can lengthen refrigerated storage time for tilapia spermatozoa. With minor modifications, these protocols can be adapted for use with sperm from other species and with other tissue types.

Quantifying small molecule phenotypic effects using mitochondrial morpho-functional fingerprinting and machine learning.

PubMed

Blanchet, Lionel; Smeitink, Jan A M; van Emst-de Vries, Sjenet E; Vogels, Caroline; Pellegrini, Mina; Jonckheere, An I; Rodenburg, Richard J T; Buydens, Lutgarde M C; Beyrath, Julien; Willems, Peter H G M; Koopman, Werner J H

2015-01-26

In primary fibroblasts from Leigh Syndrome (LS) patients, isolated mitochondrial complex I deficiency is associated with increased reactive oxygen species levels and mitochondrial morpho-functional changes. Empirical evidence suggests these aberrations constitute linked therapeutic targets for small chemical molecules. However, the latter generally induce multiple subtle effects, meaning that in vitro potency analysis or single-parameter high-throughput cell screening are of limited use to identify these molecules. We combine automated image quantification and artificial intelligence to discriminate between primary fibroblasts of a healthy individual and a LS patient based upon their mitochondrial morpho-functional phenotype. We then evaluate the effects of newly developed Trolox variants in LS patient cells. This revealed that Trolox ornithylamide hydrochloride best counterbalanced mitochondrial morpho-functional aberrations, effectively scavenged ROS and increased the maximal activity of mitochondrial complexes I, IV and citrate synthase. Our results suggest that Trolox-derived antioxidants are promising candidates in therapy development for human mitochondrial disorders.

Quantifying small molecule phenotypic effects using mitochondrial morpho-functional fingerprinting and machine learning

NASA Astrophysics Data System (ADS)

Blanchet, Lionel; Smeitink, Jan A. M.; van Emst-de Vries, Sjenet E.; Vogels, Caroline; Pellegrini, Mina; Jonckheere, An I.; Rodenburg, Richard J. T.; Buydens, Lutgarde M. C.; Beyrath, Julien; Willems, Peter H. G. M.; Koopman, Werner J. H.

2015-01-01

In primary fibroblasts from Leigh Syndrome (LS) patients, isolated mitochondrial complex I deficiency is associated with increased reactive oxygen species levels and mitochondrial morpho-functional changes. Empirical evidence suggests these aberrations constitute linked therapeutic targets for small chemical molecules. However, the latter generally induce multiple subtle effects, meaning that in vitro potency analysis or single-parameter high-throughput cell screening are of limited use to identify these molecules. We combine automated image quantification and artificial intelligence to discriminate between primary fibroblasts of a healthy individual and a LS patient based upon their mitochondrial morpho-functional phenotype. We then evaluate the effects of newly developed Trolox variants in LS patient cells. This revealed that Trolox ornithylamide hydrochloride best counterbalanced mitochondrial morpho-functional aberrations, effectively scavenged ROS and increased the maximal activity of mitochondrial complexes I, IV and citrate synthase. Our results suggest that Trolox-derived antioxidants are promising candidates in therapy development for human mitochondrial disorders.

Synthesis of cytochrome C oxidase 2: a p53-dependent metabolic regulator that promotes respiratory function and protects glioma and colon cancer cells from hypoxia-induced cell death.

PubMed

Wanka, C; Brucker, D P; Bähr, O; Ronellenfitsch, M; Weller, M; Steinbach, J P; Rieger, J

2012-08-16

P53 has an important role in the processing of starvation signals. P53-dependent molecular mediators of the Warburg effect reduce glucose consumption and promote mitochondrial function. We therefore hypothesized that the retention of wild-type p53 characteristic of primary glioblastomas limits metabolic demands induced by deregulated signal transduction in the presence of hypoxia and nutrient depletion. Here we report that short hairpin RNA-mediated gene suppression of wild-type p53 or ectopic expression of mutant temperature-sensitive dominant-negative p53(V135A) increased glucose consumption and lactate production, decreased oxygen consumption and enhanced hypoxia-induced cell death in p53 wild-type human glioblastoma cells. Similarly, genetic knockout of p53 in HCT116 colon carcinoma cells resulted in reduced respiration and hypersensitivity towards hypoxia-induced cell death. Further, wild-type p53 gene silencing reduced the expression of synthesis of cytochrome c oxidase 2 (SCO2), an effector necessary for respiratory chain function. An SCO2 transgene reverted the metabolic phenotype and restored resistance towards hypoxia in p53-depleted and p53 mutant glioma cells in a rotenone-sensitive manner, demonstrating that this effect was dependent on intact oxidative phosphorylation. Supplementation with methyl-pyruvate, a mitochondrial substrate, rescued p53 wild-type but not p53 mutant cells from hypoxic cell death, demonstrating a p53-mediated selective aptitude to metabolize mitochondrial substrates. Further, SCO2 gene silencing in p53 wild-type glioma cells sensitized these cells towards hypoxia. Finally, lentiviral gene suppression of SCO2 significantly enhanced tumor necrosis in a subcutaneous HCT116 xenograft tumor model, compatible with impaired energy metabolism in these cells. These findings demonstrate that glioma and colon cancer cells with p53 wild-type status can skew the Warburg effect and thereby reduce their vulnerability towards tumor hypoxia in an SCO2-dependent manner. Targeting SCO2 may therefore represent a valuable strategy to enhance sensitivity towards hypoxia and may complement strategies targeting glucose metabolism.

Relaxation Response Induces Temporal Transcriptome Changes in Energy Metabolism, Insulin Secretion and Inflammatory Pathways

PubMed Central

Joseph, Marie G.; Denninger, John W.; Fricchione, Gregory L.; Benson, Herbert; Libermann, Towia A.

2013-01-01

The relaxation response (RR) is the counterpart of the stress response. Millennia-old practices evoking the RR include meditation, yoga and repetitive prayer. Although RR elicitation is an effective therapeutic intervention that counteracts the adverse clinical effects of stress in disorders including hypertension, anxiety, insomnia and aging, the underlying molecular mechanisms that explain these clinical benefits remain undetermined. To assess rapid time-dependent (temporal) genomic changes during one session of RR practice among healthy practitioners with years of RR practice and also in novices before and after 8 weeks of RR training, we measured the transcriptome in peripheral blood prior to, immediately after, and 15 minutes after listening to an RR-eliciting or a health education CD. Both short-term and long-term practitioners evoked significant temporal gene expression changes with greater significance in the latter as compared to novices. RR practice enhanced expression of genes associated with energy metabolism, mitochondrial function, insulin secretion and telomere maintenance, and reduced expression of genes linked to inflammatory response and stress-related pathways. Interactive network analyses of RR-affected pathways identified mitochondrial ATP synthase and insulin (INS) as top upregulated critical molecules (focus hubs) and NF-κB pathway genes as top downregulated focus hubs. Our results for the first time indicate that RR elicitation, particularly after long-term practice, may evoke its downstream health benefits by improving mitochondrial energy production and utilization and thus promoting mitochondrial resiliency through upregulation of ATPase and insulin function. Mitochondrial resiliency might also be promoted by RR-induced downregulation of NF-κB-associated upstream and downstream targets that mitigates stress. PMID:23650531

Tetrahydrocannabinol induces brain mitochondrial respiratory chain dysfunction and increases oxidative stress: a potential mechanism involved in cannabis-related stroke.

PubMed

Wolff, Valérie; Schlagowski, Anna-Isabel; Rouyer, Olivier; Charles, Anne-Laure; Singh, François; Auger, Cyril; Schini-Kerth, Valérie; Marescaux, Christian; Raul, Jean-Sébastien; Zoll, Joffrey; Geny, Bernard

2015-01-01

Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities V max (complexes I, III, and IV activities), V succ (complexes II, III, and IV activities), V tmpd (complex IV activity), together with mitochondrial coupling (V max/V 0), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H2O2) production, measured with Amplex Red. THC significantly decreased V max (-71%; P < 0.0001), V succ (-65%; P < 0.0001), and V tmpd (-3.5%; P < 0.001). Mitochondrial coupling (V max/V 0) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H2O2 production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke.

GLP-1 promotes mitochondrial metabolism in vascular smooth muscle cells by enhancing endoplasmic reticulum-mitochondria coupling.

PubMed

Morales, Pablo E; Torres, Gloria; Sotomayor-Flores, Cristian; Peña-Oyarzún, Daniel; Rivera-Mejías, Pablo; Paredes, Felipe; Chiong, Mario

2014-03-28

Incretin GLP-1 has important metabolic effects on several tissues, mainly through the regulation of glucose uptake and usage. One mechanism for increasing cell metabolism is modulating endoplasmic reticulum (ER)-mitochondria communication, as it allows for a more efficient transfer of Ca(2+) into the mitochondria, thereby increasing activity. Control of glucose metabolism is essential for proper vascular smooth muscle cell (VSMC) function. GLP-1 has been shown to produce varied metabolic actions, but whether it regulates glucose metabolism in VSMC remains unknown. In this report, we show that GLP-1 increases mitochondrial activity in the aortic cell line A7r5 by increasing ER-mitochondria coupling. GLP-1 increases intracellular glucose and diminishes glucose uptake without altering glycogen content. ATP, mitochondrial potential and oxygen consumption increase at 3h of GLP-1 treatment, paralleled by increased Ca(2+) transfer from the ER to the mitochondria. Furthermore, GLP-1 increases levels of Mitofusin-2 (Mfn2), an ER-mitochondria tethering protein, via a PKA-dependent mechanism. Accordingly, PKA inhibition and Mfn2 down-regulation prevented mitochondrial Ca(2+) increases in GLP-1 treated cells. Inhibiting both Ca(2+) release from the ER and Ca(2+) entry into mitochondria as well as diminishing Mfn2 levels blunted the increase in mitochondrial activity in response to GLP-1. Altogether, these results strongly suggest that GLP-1 increases ER-mitochondria communication in VSMC, resulting in higher mitochondrial activity. Copyright © 2014 Elsevier Inc. All rights reserved.

Efficacy of PLGA-loaded apigenin nanoparticles in Benzo[a]pyrene and ultraviolet-B induced skin cancer of mice: mitochondria mediated apoptotic signalling cascades.

PubMed

Das, Sreemanti; Das, Jayeeta; Samadder, Asmita; Paul, Avijit; Khuda-Bukhsh, Anisur Rahman

2013-12-01

Skin cancer is increasing at an alarming rate and becoming resistant to conventional chemotherapy necessitating improved drug delivery system. We loaded apigenin (Ap), a dietary flavonoid having anti-cancer property, with poly (lactic-co-glycolide) (PLGA) nanoparticles (NAp) to explore if nano-encapsulation could enhance anti-carcinogenic effect against ultra-violet B (UVB) and Benzo(a)pyrene (BaP) induced skin tumor and mitochondrial dysfunction in mice. Particle size, morphology and zeta potential of NAp were determined using dynamic light scattering and atomic force microscopy. Tumor incidence and multiplicity in UVB-BaP induced mice with/without NAp treatment were ascertained and their histolopathological sections and chromosomal aberrations were studied. ROS accumulation and mitochondrial functioning through relevant markers like mitochondrial transmembrane potential were analyzed. Mitochondrial volume changes/swelling, cytochrome c (cyt c) release, mRNA and protein expressions of Apaf-1, bax, bcl-2, cyt c, cleaved caspase-9 and 3 were studied. Results showed that NAp produced better effects than Ap, due to their smaller size, and faster mobility. NAp reduced tissue damage and frequency of chromosomal aberrations, increased ROS accumulation to mediate mitochondrial-apoptosis through modulation of several apoptotic markers and mitochondrial matrix swelling. NAp showed ameliorative potentials in combating skin cancer and therefore has greater prospect of use in therapeutic management of skin cancer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mitochondrial DNA as an inflammatory mediator in cardiovascular diseases.

PubMed

Nakayama, Hiroyuki; Otsu, Kinya

2018-03-06

Mitochondria play a central role in multiple cellular functions, including energy production, calcium homeostasis, and cell death. Currently, growing evidence indicates the vital roles of mitochondria in triggering and maintaining inflammation. Chronic inflammation without microbial infection - termed sterile inflammation - is strongly involved in the development of heart failure. Sterile inflammation is triggered by the activation of pattern recognition receptors (PRRs) that sense endogenous ligands called damage-associated molecular patterns (DAMPs). Mitochondria release multiple DAMPs including mitochondrial DNA, peptides, and lipids, which induce inflammation via the stimulation of multiple PRRs. Among the mitochondrial DAMPs, mitochondrial DNA (mtDNA) is currently highlighted as the DAMP that mediates the activation of multiple PRRs, including Toll-like receptor 9, Nod-like receptors, and cyclic GMP-AMP synthetase/stimulator of interferon gene pathways. These PRR signalling pathways, in turn, lead to the activation of nuclear factor-κB and interferon regulatory factor, which enhances the transcriptional activity of inflammatory cytokines and interferons, and induces the recruitment of inflammatory cells. As the heart is an organ comprising abundant mitochondria for its ATP consumption (needed to maintain constant cyclic contraction and relaxation), the generation of massive amounts of mitochondrial radical oxygen species and mitochondrial DAMPs are predicted to occur and promote cardiac inflammation. Here, we will focus on the role of mtDNA in cardiac inflammation and review the mechanism and pathological significance of mtDNA-induced inflammatory responses in cardiac diseases. © 2018 The Author(s).

Editing activity for eliminating mischarged tRNAs is essential in mammalian mitochondria

PubMed Central

Hilander, Taru; Zhou, Xiao-Long; Konovalova, Svetlana; Zhang, Fu-Ping; Euro, Liliya; Chilov, Dmitri; Poutanen, Matti; Chihade, Joseph

2018-01-01

Abstract Accuracy of protein synthesis is enabled by the selection of amino acids for tRNA charging by aminoacyl-tRNA synthetases (ARSs), and further enhanced by the proofreading functions of some of these enzymes for eliminating tRNAs mischarged with noncognate amino acids. Mouse models of editing-defective cytoplasmic alanyl-tRNA synthetase (AlaRS) have previously demonstrated the importance of proofreading for cytoplasmic protein synthesis, with embryonic lethal and progressive neurodegeneration phenotypes. Mammalian mitochondria import their own set of nuclear-encoded ARSs for translating critical polypeptides of the oxidative phosphorylation system, but the importance of editing by the mitochondrial ARSs for mitochondrial proteostasis has not been known. We demonstrate here that the human mitochondrial AlaRS is capable of editing mischarged tRNAs in vitro, and that loss of the proofreading activity causes embryonic lethality in mice. These results indicate that tRNA proofreading is essential in mammalian mitochondria, and cannot be overcome by other quality control mechanisms. PMID:29228266

Mitochondrial support of persistent presynaptic vesicle mobilization with age-dependent synaptic growth after LTP

PubMed Central

Smith, Heather L; Bourne, Jennifer N; Cao, Guan; Chirillo, Michael A; Ostroff, Linnaea E; Watson, Deborah J; Harris, Kristen M

2016-01-01

Mitochondria support synaptic transmission through production of ATP, sequestration of calcium, synthesis of glutamate, and other vital functions. Surprisingly, less than 50% of hippocampal CA1 presynaptic boutons contain mitochondria, raising the question of whether synapses without mitochondria can sustain changes in efficacy. To address this question, we analyzed synapses from postnatal day 15 (P15) and adult rat hippocampus that had undergone theta-burst stimulation to produce long-term potentiation (TBS-LTP) and compared them to control or no stimulation. At 30 and 120 min after TBS-LTP, vesicles were decreased only in presynaptic boutons that contained mitochondria at P15, and vesicle decrement was greatest in adult boutons containing mitochondria. Presynaptic mitochondrial cristae were widened, suggesting a sustained energy demand. Thus, mitochondrial proximity reflected enhanced vesicle mobilization well after potentiation reached asymptote, in parallel with the apparently silent addition of new dendritic spines at P15 or the silent enlargement of synapses in adults. DOI: http://dx.doi.org/10.7554/eLife.15275.001 PMID:27991850

Mitoepigenetics and drug addiction.

PubMed

Sadakierska-Chudy, Anna; Frankowska, Małgorzata; Filip, Małgorzata

2014-11-01

Being the center of energy production in eukaryotic cells, mitochondria are also crucial for various cellular processes including intracellular Ca(2+) signaling and generation of reactive oxygen species (ROS). Mitochondria contain their own circular DNA which encodes not only proteins, transfer RNA and ribosomal RNAs but also non-coding RNAs. The most recent line of evidence indicates the presence of 5-methylcytosine and 5-hydroxymethylcytosine in mitochondrial DNA (mtDNA); thus, the level of gene expression - in a way similar to nuclear DNA - can be regulated by direct epigenetic modifications. Up to now, very little data shows the possibility of epigenetic regulation of mtDNA. Mitochondria and mtDNA are particularly important in the nervous system and may participate in the initiation of drug addiction. In fact, some addictive drugs enhance ROS production and generate oxidative stress that in turn alters mitochondrial and nuclear gene expression. This review summarizes recent findings on mitochondrial function, mtDNA copy number and epigenetics in drug addiction. Copyright © 2014 Elsevier Inc. All rights reserved.

Mitochondrial bioenergetics decay in aging: beneficial effect of melatonin.

PubMed

Paradies, Giuseppe; Paradies, Valeria; Ruggiero, Francesca M; Petrosillo, Giuseppe

2017-11-01

Aging is a biological process characterized by progressive decline in physiological functions, increased oxidative stress, reduced capacity to respond to stresses, and increased risk of contracting age-associated disorders. Mitochondria are referred to as the powerhouse of the cell through their role in the oxidative phosphorylation to generate ATP. These organelles contribute to the aging process, mainly through impairment of electron transport chain activity, opening of the mitochondrial permeability transition pore and increased oxidative stress. These events lead to damage to proteins, lipids and mitochondrial DNA. Cardiolipin, a phospholipid of the inner mitochondrial membrane, plays a pivotal role in several mitochondrial bioenergetic processes as well as in mitochondrial-dependent steps of apoptosis and in mitochondrial membrane stability and dynamics. Cardiolipin alterations are associated with mitochondrial bienergetics decline in multiple tissues in a variety of physiopathological conditions, as well as in the aging process. Melatonin, the major product of the pineal gland, is considered an effective protector of mitochondrial bioenergetic function. Melatonin preserves mitochondrial function by preventing cardiolipin oxidation and this may explain, at least in part, the protective role of this compound in mitochondrial physiopathology and aging. Here, mechanisms through which melatonin exerts its protective role against mitochondrial dysfunction associated with aging and age-associated disorders are discussed.

Neuroprotective effect of curcumin as evinced by abrogation of rotenone-induced motor deficits, oxidative and mitochondrial dysfunctions in mouse model of Parkinson's disease.

PubMed

Khatri, Dharmendra K; Juvekar, Archana R

Curcumin, a natural polyphenolic compound extracted from rhizomes of Curcuma longa (turmeric), a plant in the ginger family (Zingiberaceae) has been used worldwide and extensively in Southeast Asia. Curcumin exhibited numerous biological and pharmacological activities including potent antioxidant, cardiovascular disease, anticancer, anti-inflammatory effects and neurodegenerative disorders in cell cultures and animal models. Hence, the present study was designed in order to explore the possible neuroprotective role of curcumin against rotenone induced cognitive impairment, oxidative and mitochondrial dysfunction in mice. Chronic administration of rotenone (1mg/kg i.p.) for a period of three weeks significantly impaired cognitive function (actophotometer, rotarod and open field test), oxidative defense (increased lipid peroxidation, nitrite concentration and decreased activity of superoxide dismutase, catalase and reduced glutathione level) and mitochondrial complex (II and III) enzymes activities as compared to normal control group. Three weeks of curcumin (50, 100 and 200mg/kg, p.o.) treatment significantly improved behavioral alterations, oxidative damage and mitochondrial enzyme complex activities as compared to negative control (rotenone treated) group. Curcumin treated mice also mitigated enhanced acetylcholine esterase enzyme level as compared to negative control group. We found that curcumin restored motor deficits and enhanced the activities of antioxidant enzymes suggesting its antioxidant potential in vivo. The findings of the present study conclude neuroprotective role of curcumin against rotenone induced Parkinson's in mice and offer strong justification for the therapeutic prospective of this compound in the management of PD. Copyright © 2016. Published by Elsevier Inc.

Up-regulation of avian uncoupling protein in cold-acclimated and hyperthyroid ducklings prevents reactive oxygen species production by skeletal muscle mitochondria.

PubMed

Rey, Benjamin; Roussel, Damien; Romestaing, Caroline; Belouze, Maud; Rouanet, Jean-Louis; Desplanches, Dominique; Sibille, Brigitte; Servais, Stéphane; Duchamp, Claude

2010-04-28

Although identified in several bird species, the biological role of the avian homolog of mammalian uncoupling proteins (avUCP) remains extensively debated. In the present study, the functional properties of isolated mitochondria were examined in physiological or pharmacological situations that induce large changes in avUCP expression in duckling skeletal muscle. The abundance of avUCP mRNA, as detected by RT-PCR in gastrocnemius muscle but not in the liver, was markedly increased by cold acclimation (CA) or pharmacological hyperthyroidism but was down-regulated by hypothyroidism. Activators of UCPs, such as superoxide with low doses of fatty acids, stimulated a GDP-sensitive proton conductance across the inner membrane of muscle mitochondria from CA or hyperthyroid ducklings. The stimulation was much weaker in controls and not observed in hypothyroid ducklings or in any liver mitochondrial preparations. The production of endogenous mitochondrial reactive oxygen species (ROS) was much lower in muscle mitochondria from CA and hyperthyroid ducklings than in the control or hypothyroid groups. The addition of GDP markedly increased the mitochondrial ROS production of CA or hyperthyroid birds up to, or above, the level of control or hypothyroid ducklings. Differences in ROS production among groups could not be attributed to changes in antioxidant enzyme activities (superoxide dismutase or glutathione peroxidase). This work provides the first functional in vitro evidence that avian UCP regulates mitochondrial ROS production in situations of enhanced metabolic activity.

Up-regulation of avian uncoupling protein in cold-acclimated and hyperthyroid ducklings prevents reactive oxygen species production by skeletal muscle mitochondria

PubMed Central

2010-01-01

Background Although identified in several bird species, the biological role of the avian homolog of mammalian uncoupling proteins (avUCP) remains extensively debated. In the present study, the functional properties of isolated mitochondria were examined in physiological or pharmacological situations that induce large changes in avUCP expression in duckling skeletal muscle. Results The abundance of avUCP mRNA, as detected by RT-PCR in gastrocnemius muscle but not in the liver, was markedly increased by cold acclimation (CA) or pharmacological hyperthyroidism but was down-regulated by hypothyroidism. Activators of UCPs, such as superoxide with low doses of fatty acids, stimulated a GDP-sensitive proton conductance across the inner membrane of muscle mitochondria from CA or hyperthyroid ducklings. The stimulation was much weaker in controls and not observed in hypothyroid ducklings or in any liver mitochondrial preparations. The production of endogenous mitochondrial reactive oxygen species (ROS) was much lower in muscle mitochondria from CA and hyperthyroid ducklings than in the control or hypothyroid groups. The addition of GDP markedly increased the mitochondrial ROS production of CA or hyperthyroid birds up to, or above, the level of control or hypothyroid ducklings. Differences in ROS production among groups could not be attributed to changes in antioxidant enzyme activities (superoxide dismutase or glutathione peroxidase). Conclusion This work provides the first functional in vitro evidence that avian UCP regulates mitochondrial ROS production in situations of enhanced metabolic activity. PMID:20426850

Astaxanthin prevents pulmonary fibrosis by promoting myofibroblast apoptosis dependent on Drp1-mediated mitochondrial fission

PubMed Central

Zhang, Jinjin; Xu, Pan; Wang, Youlei; Wang, Meirong; Li, Hongbo; Lin, Shengcui; Mao, Cuiping; Wang, Bingsi; Song, Xiaodong; Lv, Changjun

2015-01-01

Promotion of myofibroblast apoptosis is a potential therapeutic strategy for pulmonary fibrosis. This study investigated the antifibrotic effect of astaxanthin on the promotion of myofibroblast apoptosis based on dynamin-related protein-1 (Drp1)-mediated mitochondrial fission in vivo and in vitro. Results showed that astaxanthin can inhibit lung parenchymal distortion and collagen deposition, as well as promote myofibroblast apoptosis. Astaxanthin demonstrated pro-apoptotic function in myofibroblasts by contributing to mitochondrial fission, thereby leading to apoptosis by increasing the Drp1 expression and enhancing Drp1 translocation into the mitochondria. Two specific siRNAs were used to demonstrate that Drp1 is necessary to promote astaxanthin-induced mitochondrial fission and apoptosis in myofibroblasts. Drp1-associated genes, such as Bcl-2-associated X protein, cytochrome c, tumour suppressor gene p53 and p53-up-regulated modulator of apoptosis, were highly up-regulated in the astaxanthin group compared with those in the sham group. This study revealed that astaxanthin can prevent pulmonary fibrosis by promoting myofibroblast apoptosis through a Drp1-dependent molecular pathway. Furthermore, astaxanthin provides a potential therapeutic value in pulmonary fibrosis treatment. PMID:26119034

The Ablation of Mitochondrial Protein Phosphatase Pgam5 Confers Resistance Against Metabolic Stress.

PubMed

Sekine, Shiori; Yao, Akari; Hattori, Kazuki; Sugawara, Sho; Naguro, Isao; Koike, Masato; Uchiyama, Yasuo; Takeda, Kohsuke; Ichijo, Hidenori

2016-03-01

Phosphoglycerate mutase family member 5 (PGAM5) is a mitochondrial protein phosphatase that has been reported to be involved in various stress responses from mitochondrial quality control to cell death. However, its roles in vivo are largely unknown. Here, we show that Pgam5-deficient mice are resistant to several metabolic insults. Under cold stress combined with fasting, Pgam5-deficient mice better maintained body temperature than wild-type mice and showed an extended survival rate. Serum triglycerides and lipid content in brown adipose tissue (BAT), a center of adaptive thermogenesis, were severely reduced in Pgam5-deficient mice. Moreover, although Pgam5 deficiency failed to maintain proper mitochondrial integrity in BAT, it reciprocally resulted in the dramatic induction of fibroblast growth factor 21 (FGF21) that activates various functions of BAT including thermogenesis. Thus, the enhancement of lipid metabolism and FGF21 may contribute to the cold resistance of Pgam5-deficient mice under fasting condition. Finally, we also found that Pgam5-deficient mice are resistant to high-fat-diet-induced obesity. Our study uncovered that PGAM5 is involved in the whole-body metabolism in response to stresses that impose metabolic challenges on mitochondria.

Targeted iron oxide nanoparticles for the enhancement of radiation therapy

PubMed Central

Hauser, Anastasia K.; Mitov, Mihail I.; Daley, Emily F.; McGarry, Ronald C.; Anderson, Kimberly W.; Hilt, J. Zach

2017-01-01

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. PMID:27521615

Enhanced resistance to permeability transition in interfibrillar cardiac mitochondria in dogs: effects of aging and long-term aldosterone infusion

PubMed Central

Asemu, Girma; O'Connell, Kelly A.; Cox, James W.; Dabkowski, Erinne R.; Xu, Wenhong; Ribeiro, Rogerio F.; Shekar, Kadambari C.; Hecker, Peter A.; Rastogi, Sharad; Sabbah, Hani N.; Hoppel, Charles L.

2013-01-01

Functional differences between subsarcolemmal and interfibrillar cardiac mitochondria (SSM and IFM) have been observed with aging and pathological conditions in rodents. Results are contradictory, and there is little information from large animal models. We assessed the respiratory function and resistance to mitochondrial permeability transition (MPT) in SSM and IFM from healthy young (1 yr) and old (8 yr) female beagles and in old beagles with hypertension and left ventricular (LV) wall thickening induced by 16 wk of aldosterone infusion. MPT was assessed in SSM and IFM by Ca2+ retention and swelling. Healthy young and old beagles had similar mitochondrial structure, respiratory function, and Ca2+-induced MPT within SSM and IFM subpopulations. On the other hand, oxidative capacity and resistance to Ca2+-induced MPT were significantly greater in IFM compared with SSM in all groups. Old beagles treated with aldosterone had greater LV wall thickness and worse diastolic filling but normal LV chamber volume and systolic function. Treatment with aldosterone did not alter mitochondrial respiratory function but accelerated Ca2+-induced MPT in SSM, but not IFM, compared with healthy old and young beagles. In conclusion, in a large animal model, oxidative capacity and resistance to MPT were greater in IFM than in SSM. Furthermore, aldosterone infusion increased susceptibility to MPT in SSM, but not IFM. Together this suggests that SSM are less resilient to acute stress than IFM in the healthy heart and are more susceptible to the development of pathology with chronic stress. PMID:23241318

Enhanced resistance to permeability transition in interfibrillar cardiac mitochondria in dogs: effects of aging and long-term aldosterone infusion.

PubMed

Asemu, Girma; O'Connell, Kelly A; Cox, James W; Dabkowski, Erinne R; Xu, Wenhong; Ribeiro, Rogerio F; Shekar, Kadambari C; Hecker, Peter A; Rastogi, Sharad; Sabbah, Hani N; Hoppel, Charles L; Stanley, William C

2013-02-15

Functional differences between subsarcolemmal and interfibrillar cardiac mitochondria (SSM and IFM) have been observed with aging and pathological conditions in rodents. Results are contradictory, and there is little information from large animal models. We assessed the respiratory function and resistance to mitochondrial permeability transition (MPT) in SSM and IFM from healthy young (1 yr) and old (8 yr) female beagles and in old beagles with hypertension and left ventricular (LV) wall thickening induced by 16 wk of aldosterone infusion. MPT was assessed in SSM and IFM by Ca(2+) retention and swelling. Healthy young and old beagles had similar mitochondrial structure, respiratory function, and Ca(2+)-induced MPT within SSM and IFM subpopulations. On the other hand, oxidative capacity and resistance to Ca(2+)-induced MPT were significantly greater in IFM compared with SSM in all groups. Old beagles treated with aldosterone had greater LV wall thickness and worse diastolic filling but normal LV chamber volume and systolic function. Treatment with aldosterone did not alter mitochondrial respiratory function but accelerated Ca(2+)-induced MPT in SSM, but not IFM, compared with healthy old and young beagles. In conclusion, in a large animal model, oxidative capacity and resistance to MPT were greater in IFM than in SSM. Furthermore, aldosterone infusion increased susceptibility to MPT in SSM, but not IFM. Together this suggests that SSM are less resilient to acute stress than IFM in the healthy heart and are more susceptible to the development of pathology with chronic stress.

SMG-1 kinase attenuates mitochondrial ROS production but not cell respiration deficits during hyperoxia.

PubMed

Resseguie, Emily A; Brookes, Paul S; O'Reilly, Michael A

Supplemental oxygen (hyperoxia) used to treat individuals in respiratory distress causes cell injury by enhancing the production of toxic reactive oxygen species (ROS) and inhibiting mitochondrial respiration. The suppressor of morphogenesis of genitalia (SMG-1) kinase is activated during hyperoxia and promotes cell survival by phosphorylating the tumor suppressor p53 on serine 15. Here, we investigate whether SMG-1 and p53 blunt this vicious cycle of progressive ROS production and decline in mitochondrial respiration seen during hyperoxia. Human lung adenocarcinoma A549 and H1299 or colon carcinoma HCT116 cells were depleted of SMG-1, UPF-1, or p53 using RNA interference, and then exposed to room air (21% oxygen) or hyperoxia (95% oxygen). Immunoblotting was used to evaluate protein expression; a Seahorse Bioanalyzer was used to assess cellular respiration; and flow cytometry was used to evaluate fluorescence intensity of cells stained with mitochondrial or redox sensitive dyes. Hyperoxia increased mitochondrial and cytoplasmic ROS and suppressed mitochondrial respiration without changing mitochondrial mass or membrane potential. Depletion of SMG-1 or its cofactor, UPF1, significantly enhanced hyperoxia-induced mitochondrial but not cytosolic ROS abundance. They did not affect mitochondrial mass, membrane potential, or hyperoxia-induced deficits in mitochondrial respiration. Genetic depletion of p53 in A549 cells and ablation of the p53 gene in H1299 or HCT116 cells revealed that SMG-1 influences mitochondrial ROS through activation of p53. Our findings show that hyperoxia does not promote a vicious cycle of progressive mitochondrial ROS and dysfunction because SMG-1-p53 signaling attenuates production of mitochondrial ROS without preserving respiration. This suggests antioxidant therapies that blunt ROS production during hyperoxia may not suffice to restore cellular respiration.

A Molecular Approach to Mitophagy and Mitochondrial Dynamics

PubMed Central

Yoo, Seung-Min; Jung, Yong-Keun

2018-01-01

Mitochondrial quality control systems are essential for the maintenance of functional mitochondria. At the organelle level, they include mitochondrial biogenesis, fusion and fission, to compensate for mitochondrial function, and mitophagy, for degrading damaged mitochondria. Specifically, in mitophagy, the target mitochondria are recognized by the autophagosomes and delivered to the lysosome for degradation. In this review, we describe the mechanisms of mitophagy and the factors that play an important role in this process. In particular, we focus on the roles of mitophagy adapters and receptors in the recognition of damaged mitochondria by autophagosomes. In addition, we also address a functional association of mitophagy with mitochondrial dynamics through the interaction of mitophagy adaptor and receptor proteins with mitochondrial fusion and fission proteins. PMID:29370689

Monomeric Alpha-Synuclein Exerts a Physiological Role on Brain ATP Synthase

PubMed Central

Ludtmann, Marthe H.R.; Angelova, Plamena R.; Ninkina, Natalia N.; Gandhi, Sonia

2016-01-01

Misfolded α-synuclein is a key factor in the pathogenesis of Parkinson's disease (PD). However, knowledge about a physiological role for the native, unfolded α-synuclein is limited. Using brains of mice lacking α-, β-, and γ-synuclein, we report that extracellular monomeric α-synuclein enters neurons and localizes to mitochondria, interacts with ATP synthase subunit α, and modulates ATP synthase function. Using a combination of biochemical, live-cell imaging and mitochondrial respiration analysis, we found that brain mitochondria of α-, β-, and γ-synuclein knock-out mice are uncoupled, as characterized by increased mitochondrial respiration and reduced mitochondrial membrane potential. Furthermore, synuclein deficiency results in reduced ATP synthase efficiency and lower ATP levels. Exogenous application of low unfolded α-synuclein concentrations is able to increase the ATP synthase activity that rescues the mitochondrial phenotypes observed in synuclein deficiency. Overall, the data suggest that α-synuclein is a previously unrecognized physiological regulator of mitochondrial bioenergetics through its ability to interact with ATP synthase and increase its efficiency. This may be of particular importance in times of stress or PD mutations leading to energy depletion and neuronal cell toxicity. SIGNIFICANCE STATEMENT Misfolded α-synuclein aggregations in the form of Lewy bodies have been shown to be a pathological hallmark in histological staining of Parkinson's disease (PD) patient brains. It is known that misfolded α-synuclein is a key driver in PD pathogenesis, but the physiological role of unfolded monomeric α-synuclein remains unclear. Using neuronal cocultures and isolated brain mitochondria of α-, β-, and γ-synuclein knock-out mice and monomeric α-synuclein, this current study shows that α-synuclein in its unfolded monomeric form improves ATP synthase efficiency and mitochondrial function. The ability of monomeric α-synuclein to enhance ATP synthase efficiency under physiological conditions may be of importance when α-synuclein undergoes the misfolding and aggregation reported in PD. PMID:27733604

Ethanol Influences on Bax Translocation, Mitochondrial Membrane Potential, and Reactive Oxygen Species Generation are Modulated by Vitamin E and Brain-Derived Neurotrophic Factor

PubMed Central

Heaton, Marieta Barrow; Paiva, Michael; Siler-Marsiglio, Kendra

2011-01-01

Background This study investigated ethanol influences on intracellular events which predispose developing neurons toward apoptosis, and the capacity of the antioxidant α-tocopherol (vitamin E) and the neurotrophin brain-derived neurotrophic factor (BDNF) to modulate these effects. Assessments were made of the following: (1) ethanol-induced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane, a key upstream event in the initiation of apoptotic cell death; (2) disruption of the mitochondrial membrane potential (MMP) as a result of ethanol exposure, an important process in triggering the apoptotic cascade; and (3) generation of damaging reactive oxygen species (ROS) as a function of ethanol exposure. Methods These interactions were investigated in cultured postnatal day 8 neonatal rat cerebellar granule cells, a population vulnerable to developmental ethanol exposure in vivo and in vitro. Bax mitochondrial translocation was analyzed via subcellular fractionation followed by Western blot, and mitochondrial membrane integrity was determined using the lipophilic dye, JC-1, which exhibits potential-dependent accumulation in the mitochondrial membrane as a function of the MMP. Results Brief ethanol exposure in these preparations precipitated Bax translocation, but both vitamin E and BDNF reduced this effect to control levels. Ethanol treatment also resulted in a disturbance of the MMP, and this effect was blunted by the antioxidant and the neurotrophin. ROS generation was enhanced by a short ethanol exposure in these cells, but the production of these harmful free radicals was diminished to control levels by co-treatment with either vitamin E or BDNF. Conclusions These results indicate that both antioxidants and neurotrophic factors have the potential to ameliorate ethanol neurotoxicity, and suggest possible interventions which could be implemented in preventing or lessening the severity of the damaging effects of ethanol in the developing central nervous system seen in the fetal alcohol syndrome (FAS). PMID:21332533

Lactate and Pyruvate Are Major Sources of Energy for Stallion Sperm with Dose Effects on Mitochondrial Function, Motility, and ROS Production.

PubMed

Darr, Christa R; Varner, Dickson D; Teague, Sheila; Cortopassi, Gino A; Datta, Sandipan; Meyers, Stuart A

2016-08-01

Stallion sperm rely primarily on oxidative phosphorylation for production of ATP used in sperm motility and metabolism. The objective of the study was to identify which substrates included in Biggers, Whitten, and Whittingham (BWW) media are key to optimal mitochondrial function through measurements of sperm motility parameters, mitochondrial oxygen consumption, and cellular reactive oxygen species (ROS) production. It was expected that mitochondrial substrates, pyruvate and lactate, would support sperm motility and mitochondrial function better than the glycolytic substrate, glucose, due to direct utilization within the mitochondria. Measurements were performed after incubation in modified BWW media with varying concentrations of lactate, pyruvate, and glucose. The effects of media and duration of incubation on sperm motility, ROS production, and oxygen consumption were determined using a linear mixed-effects model. Duplicate ejaculates from four stallions were used in three separate experiments to determine the effects of substrate availability and concentration on sperm motility and mitochondrial function and the relationship of oxygen consumption with cellular ROS production. The present results indicate that lactate and pyruvate are the most important sources of energy for stallion sperm motility and velocity, and elicit a dose-dependent response. Additionally, lactate and pyruvate are ideal for maximal mitochondrial function, as sperm in these media operate at a very high level of their bioenergetic capability due to the high rate of energy metabolism. Moreover, we found that addition of glucose to the media is not necessary for short-term storage of equine sperm, and may even result in reduction of mitochondrial function. Finally, we have confirmed that ROS production can be the result of mitochondrial dysfunction as well as intense mitochondrial activity. © 2016 by the Society for the Study of Reproduction, Inc.

Functional Diversity of Human Mitochondrial J-proteins Is Independent of Their Association with the Inner Membrane Presequence Translocase.

PubMed

Sinha, Devanjan; Srivastava, Shubhi; D'Silva, Patrick

2016-08-12

Mitochondrial J-proteins play a critical role in governing Hsp70 activity and, hence, are essential for organellar protein translocation and folding. In contrast to yeast, which has a single J-protein Pam18, humans involve two J-proteins, DnaJC15 and DnaJC19, associated with contrasting cellular phenotype, to transport proteins into the mitochondria. Mutation in DnaJC19 results in dilated cardiomyopathy and ataxia syndrome, whereas expression of DnaJC15 regulates the response of cancer cells to chemotherapy. In the present study we have comparatively assessed the biochemical properties of the J-protein paralogs in relation to their association with the import channel. Both DnaJC15 and DnaJC19 formed two distinct subcomplexes with Magmas at the import channel. Knockdown analysis suggested an essential role for Magmas and DnaJC19 in organellar protein translocation and mitochondria biogenesis, whereas DnaJC15 had dispensable supportive function. The J-proteins were found to have equal affinity for Magmas and could stimulate mitochondrial Hsp70 ATPase activity by equivalent levels. Interestingly, we observed that DnaJC15 exhibits bifunctional properties. At the translocation channel, it involves conserved interactions and mechanism to translocate the precursors into mitochondria. In addition to protein transport, DnaJC15 also showed a dual role in yeast where its expression elicited enhanced sensitivity of cells to cisplatin that required the presence of a functional J-domain. The amount of DnaJC15 expressed in the cell was directly proportional to the sensitivity of cells. Our analysis indicates that the differential cellular phenotype displayed by human mitochondrial J-proteins is independent of their activity and association with Magmas at the translocation channel. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

N-terminal functional domain of Gasdermin A3 regulates mitochondrial homeostasis via mitochondrial targeting.

PubMed

Lin, Pei-Hsuan; Lin, Hsien-Yi; Kuo, Cheng-Chin; Yang, Liang-Tung

2015-06-24

The epidermis forms a critical barrier that is maintained by orchestrated programs of proliferation, differentiation, and cell death. Gene mutations that disturb this turnover process may cause skin diseases. Human GASDERMIN A (GSDMA) is frequently silenced in gastric cancer cell lines and its overexpression has been reported to induce apoptosis. GSDMA has also been linked with airway hyperresponsiveness in genetic association studies. The function of GSDMA in the skin was deduced by dominant mutations in mouse gasdermin A3 (Gsdma3), which caused skin inflammation and hair loss. However, the mechanism for the autosomal dominance of Gsdma3 mutations and the mode of Gsdma3's action remain unanswered. We demonstrated a novel function of Gsdma3 in modulating mitochondrial oxidative stress. We showed that Gsdma3 is regulated by intramolecular fold-back inhibition, which is disrupted by dominant mutations in the C-terminal domain. The unmasked N-terminal domain of Gsdma3 associates with Hsp90 and is delivered to mitochondrial via mitochondrial importer receptor Tom70, where it interacts with the mitochondrial chaperone Trap1 and causes increased production of mitochondrial reactive oxygen species (ROS), dissipation of mitochondrial membrane potential, and mitochondrial permeability transition (MPT). Overexpression of the C-terminal domain of Gsdma3 as well as pharmacological interventions of mitochondrial translocation, ROS production, and MPT pore opening alleviate the cell death induced by Gsdma3 mutants. Our results indicate that the genetic mutations in the C-terminal domain of Gsdma3 are gain-of-function mutations which unmask the N-terminal functional domain of Gsdma3. Gsdma3 regulates mitochondrial oxidative stress through mitochondrial targeting. Since mitochondrial ROS has been shown to promote epidermal differentiation, we hypothesize that Gsdma3 regulates context-dependent response of keratinocytes to differentiation and cell death signals by impinging on mitochondria.

Enhanced oxidative stress and aberrant mitochondrial biogenesis in human neuroblastoma SH-SY5Y cells during methamphetamine induced apoptosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, C.-W.; Ping, Y.-H.; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan

2007-05-01

Methamphetamine (METH) is an abused drug that may cause psychiatric and neurotoxic damage, including degeneration of monoaminergic terminals and apoptosis of non-monoaminergic cells in Brain. The cellular and molecular mechanisms underlying these METH-induced neurotoxic effects remain to be clarified. In this study, we performed a time course assessment to investigate the effects of METH on intracellular oxidative stress and mitochondrial alterations in a human dopaminergic neuroblastoma SH-SY5Y cell line. We characterized that METH induces a temporal sequence of several cellular events including, firstly, a decrease in mitochondrial membrane potential within 1 h of the METH treatment, secondly, an extensive declinemore » in mitochondrial membrane potential and increase in the level of reactive oxygen species (ROS) after 8 h of the treatment, thirdly, an increase in mitochondrial mass after the drug treatment for 24 h, and finally, a decrease in mtDNA copy number and mitochondrial proteins per mitochondrion as well as the occurrence of apoptosis after 48 h of the treatment. Importantly, vitamin E attenuated the METH-induced increases in intracellular ROS level and mitochondrial mass, and prevented METH-induced cell death. Our observations suggest that enhanced oxidative stress and aberrant mitochondrial biogenesis may play critical roles in METH-induced neurotoxic effects.« less

Changes in mitochondrial function and mitochondria associated protein expression in response to 2-weeks of high intensity interval training

PubMed Central

Vincent, Grace; Lamon, Séverine; Gant, Nicholas; Vincent, Peter J.; MacDonald, Julia R.; Markworth, James F.; Edge, Johann A.; Hickey, Anthony J. R.

2015-01-01

Purpose: High-intensity short-duration interval training (HIT) stimulates functional and metabolic adaptation in skeletal muscle, but the influence of HIT on mitochondrial function remains poorly studied in humans. Mitochondrial metabolism as well as mitochondrial-associated protein expression were tested in untrained participants performing HIT over a 2-week period. Methods: Eight males performed a single-leg cycling protocol (12 × 1 min intervals at 120% peak power output, 90 s recovery, 4 days/week). Muscle biopsies (vastus lateralis) were taken pre- and post-HIT. Mitochondrial respiration in permeabilized fibers, citrate synthase (CS) activity and protein expression of peroxisome proliferator-activated receptor gamma coactivator (PGC-1α) and respiratory complex components were measured. Results: HIT training improved peak power and time to fatigue. Increases in absolute oxidative phosphorylation (OXPHOS) capacities and CS activity were observed, but not in the ratio of CCO to the electron transport system (CCO/ETS), the respiratory control ratios (RCR-1 and RCR-2) or mitochondrial-associated protein expression. Specific increases in OXPHOS flux were not apparent after normalization to CS, indicating that gross changes mainly resulted from increased mitochondrial mass. Conclusion: Over only 2 weeks HIT significantly increased mitochondrial function in skeletal muscle independently of detectable changes in mitochondrial-associated and mitogenic protein expression. PMID:25759671

Mitochondrial telomerase reverse transcriptase binds to and protects mitochondrial DNA and function from damage.

PubMed

Haendeler, Judith; Dröse, Stefan; Büchner, Nicole; Jakob, Sascha; Altschmied, Joachim; Goy, Christine; Spyridopoulos, Ioakim; Zeiher, Andreas M; Brandt, Ulrich; Dimmeler, Stefanie

2009-06-01

The enzyme telomerase and its catalytic subunit the telomerase reverse transcriptase (TERT) are important for maintenance of telomere length in the nucleus. Recent studies provided evidence for a mitochondrial localization of TERT. Therefore, we investigated the exact localization of TERT within the mitochondria and its function. Here, we demonstrate that TERT is localized in the matrix of the mitochondria. TERT binds to mitochondrial DNA at the coding regions for ND1 and ND2. Binding of TERT to mitochondrial DNA protects against ethidium bromide-induced damage. TERT increases overall respiratory chain activity, which is most pronounced at complex I and dependent on the reverse transcriptase activity of the enzyme. Moreover, mitochondrial reactive oxygen species are increased after genetic ablation of TERT by shRNA. Mitochondrially targeted TERT and not wild-type TERT revealed the most prominent protective effect on H(2)O(2)-induced apoptosis. Lung fibroblasts from 6-month-old TERT(-/-) mice (F2 generation) showed increased sensitivity toward UVB radiation and heart mitochondria exhibited significantly reduced respiratory chain activity already under basal conditions, demonstrating the protective function of TERT in vivo. Mitochondrial TERT exerts a novel protective function by binding to mitochondrial DNA, increasing respiratory chain activity and protecting against oxidative stress-induced damage.

Mechanisms Underlying the Essential Role of Mitochondrial Membrane Lipids in Yeast Chronological Aging

PubMed Central

Medkour, Younes; Dakik, Paméla; McAuley, Mélissa; Mohammad, Karamat; Mitrofanova, Darya

2017-01-01

The functional state of mitochondria is vital to cellular and organismal aging in eukaryotes across phyla. Studies in the yeast Saccharomyces cerevisiae have provided evidence that age-related changes in some aspects of mitochondrial functionality can create certain molecular signals. These signals can then define the rate of cellular aging by altering unidirectional and bidirectional communications between mitochondria and other organelles. Several aspects of mitochondrial functionality are known to impact the replicative and/or chronological modes of yeast aging. They include mitochondrial electron transport, membrane potential, reactive oxygen species, and protein synthesis and proteostasis, as well as mitochondrial synthesis of iron-sulfur clusters, amino acids, and NADPH. Our recent findings have revealed that the composition of mitochondrial membrane lipids is one of the key aspects of mitochondrial functionality affecting yeast chronological aging. We demonstrated that exogenously added lithocholic bile acid can delay chronological aging in yeast because it elicits specific changes in mitochondrial membrane lipids. These changes allow mitochondria to operate as signaling platforms that delay yeast chronological aging by orchestrating an institution and maintenance of a distinct cellular pattern. In this review, we discuss molecular and cellular mechanisms underlying the essential role of mitochondrial membrane lipids in yeast chronological aging. PMID:28593023

Avocado Oil Improves Mitochondrial Function and Decreases Oxidative Stress in Brain of Diabetic Rats.

PubMed

Ortiz-Avila, Omar; Esquivel-Martínez, Mauricio; Olmos-Orizaba, Berenice Eridani; Saavedra-Molina, Alfredo; Rodriguez-Orozco, Alain R; Cortés-Rojo, Christian

2015-01-01

Diabetic encephalopathy is a diabetic complication related to the metabolic alterations featuring diabetes. Diabetes is characterized by increased lipid peroxidation, altered glutathione redox status, exacerbated levels of ROS, and mitochondrial dysfunction. Although the pathophysiology of diabetic encephalopathy remains to be clarified, oxidative stress and mitochondrial dysfunction play a crucial role in the pathogenesis of chronic diabetic complications. Taking this into consideration, the aim of this work was to evaluate the effects of 90-day avocado oil intake in brain mitochondrial function and oxidative status in streptozotocin-induced diabetic rats (STZ rats). Avocado oil improves brain mitochondrial function in diabetic rats preventing impairment of mitochondrial respiration and mitochondrial membrane potential (ΔΨ m ), besides increasing complex III activity. Avocado oil also decreased ROS levels and lipid peroxidation and improved the GSH/GSSG ratio as well. These results demonstrate that avocado oil supplementation prevents brain mitochondrial dysfunction induced by diabetes in association with decreased oxidative stress.

Homozygous YME1L1 mutation causes mitochondriopathy with optic atrophy and mitochondrial network fragmentation.

PubMed

Hartmann, Bianca; Wai, Timothy; Hu, Hao; MacVicar, Thomas; Musante, Luciana; Fischer-Zirnsak, Björn; Stenzel, Werner; Gräf, Ralph; van den Heuvel, Lambert; Ropers, Hans-Hilger; Wienker, Thomas F; Hübner, Christoph; Langer, Thomas; Kaindl, Angela M

2016-08-06

Mitochondriopathies often present clinically as multisystemic disorders of primarily high-energy consuming organs. Assembly, turnover, and surveillance of mitochondrial proteins are essential for mitochondrial function and a key task of AAA family members of metalloproteases. We identified a homozygous mutation in the nuclear encoded mitochondrial escape 1-like 1 gene YME1L1, member of the AAA protease family, as a cause of a novel mitochondriopathy in a consanguineous pedigree of Saudi Arabian descent. The homozygous missense mutation, located in a highly conserved region in the mitochondrial pre-sequence, inhibits cleavage of YME1L1 by the mitochondrial processing peptidase, which culminates in the rapid degradation of YME1L1 precursor protein. Impaired YME1L1 function causes a proliferation defect and mitochondrial network fragmentation due to abnormal processing of OPA1. Our results identify mutations in YME1L1 as a cause of a mitochondriopathy with optic nerve atrophy highlighting the importance of YME1L1 for mitochondrial functionality in humans.

Imbalance of mitochondrial dynamics in Drosophila models of amyotrophic lateral sclerosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altanbyek, Volodya; Cha, Sun-Joo; Kang, Ga-Un

Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative disease, characterized by progressive and selective loss of motor neurons in the brain and spinal cord. DNA/RNA-binding proteins such as TDP-43, FUS, and TAF15 have been linked with the sporadic and familial forms of ALS. However, the exact pathogenic mechanism of ALS is still unknown. Recently, we found that ALS-causing genes such as TDP-43, FUS, and TAF15 genetically interact with mitochondrial dynamics regulatory genes. In this study, we show that mitochondrial fission was highly enhanced in muscles and motor neurons of TDP-43, FUS, and TAF15-induced fly models of ALS. Furthermore, themore » mitochondrial fission defects were rescued by co-expression of mitochondrial dynamics regulatory genes such as Marf, Opa1, and the dominant negative mutant form of Drp1. Moreover, we found that the expression level of Marf was decreased in ALS-induced flies. These results indicate that the imbalance of mitochondrial dynamics caused by instability of Marf is linked to the pathogenesis of TDP-43, FUS, and TAF15-associated ALS. - Highlights: • Mitochondrial fission is highly enhanced in TDP-43, FUS, and TAF15-induced fly models of ALS. • Excessive mitochondrial fragmentation in fly models of ALS is restored by mitochondrial dynamics regulatory genes. • Level of Marf protein is decreased in TDP-43, FUS, and TAF15-mediated ALS. • Imbalance of mitochondrial dynamics caused by Marf instability is linked to the pathogenesis of ALS.« less

MICOS and phospholipid transfer by Ups2-Mdm35 organize membrane lipid synthesis in mitochondria.

PubMed

Aaltonen, Mari J; Friedman, Jonathan R; Osman, Christof; Salin, Bénédicte; di Rago, Jean-Paul; Nunnari, Jodi; Langer, Thomas; Tatsuta, Takashi

2016-06-06

Mitochondria exert critical functions in cellular lipid metabolism and promote the synthesis of major constituents of cellular membranes, such as phosphatidylethanolamine (PE) and phosphatidylcholine. Here, we demonstrate that the phosphatidylserine decarboxylase Psd1, located in the inner mitochondrial membrane, promotes mitochondrial PE synthesis via two pathways. First, Ups2-Mdm35 complexes (SLMO2-TRIAP1 in humans) serve as phosphatidylserine (PS)-specific lipid transfer proteins in the mitochondrial intermembrane space, allowing formation of PE by Psd1 in the inner membrane. Second, Psd1 decarboxylates PS in the outer membrane in trans, independently of PS transfer by Ups2-Mdm35. This latter pathway requires close apposition between both mitochondrial membranes and the mitochondrial contact site and cristae organizing system (MICOS). In MICOS-deficient cells, limiting PS transfer by Ups2-Mdm35 and reducing mitochondrial PE accumulation preserves mitochondrial respiration and cristae formation. These results link mitochondrial PE metabolism to MICOS, combining functions in protein and lipid homeostasis to preserve mitochondrial structure and function. © 2016 Aaltonen et al.

MITOCHONDRIAL DISEASES PART II: MOUSE MODELS OF OXPHOS DEFICIENCIES CAUSED BY DEFECTS IN REGULATORY FACTORS AND OTHER COMPONENTS REQUIRED FOR MITOCHONDRIAL FUNCTION

PubMed Central

Iommarini, Luisa; Peralta, Susana; Torraco, Alessandra; Diaz, Francisca

2015-01-01

Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well to other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without been intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms. PMID:25640959

The destiny of Ca(2+) released by mitochondria.

PubMed

Takeuchi, Ayako; Kim, Bongju; Matsuoka, Satoshi

2015-01-01

Mitochondrial Ca(2+) is known to regulate diverse cellular functions, for example energy production and cell death, by modulating mitochondrial dehydrogenases, inducing production of reactive oxygen species, and opening mitochondrial permeability transition pores. In addition to the action of Ca(2+) within mitochondria, Ca(2+) released from mitochondria is also important in a variety of cellular functions. In the last 5 years, the molecules responsible for mitochondrial Ca(2+) dynamics have been identified: a mitochondrial Ca(2+) uniporter (MCU), a mitochondrial Na(+)-Ca(2+) exchanger (NCLX), and a candidate for a mitochondrial H(+)-Ca(2+) exchanger (Letm1). In this review, we focus on the mitochondrial Ca(2+) release system, and discuss its physiological and pathophysiological significance. Accumulating evidence suggests that the mitochondrial Ca(2+) release system is not only crucial in maintaining mitochondrial Ca(2+) homeostasis but also participates in the Ca(2+) crosstalk between mitochondria and the plasma membrane and between mitochondria and the endoplasmic/sarcoplasmic reticulum.

MELAS syndrome and cardiomyopathy: linking mitochondrial function to heart failure pathogenesis.

PubMed

Hsu, Ying-Han R; Yogasundaram, Haran; Parajuli, Nirmal; Valtuille, Lucas; Sergi, Consolato; Oudit, Gavin Y

2016-01-01

Heart failure remains an important clinical burden, and mitochondrial dysfunction plays a key role in its pathogenesis. The heart has a high metabolic demand, and mitochondrial function is a key determinant of myocardial performance. In mitochondrial disorders, hypertrophic remodeling is the early pattern of cardiomyopathy with progression to dilated cardiomyopathy, conduction defects and ventricular pre-excitation occurring in a significant proportion of patients. Cardiac dysfunction occurs in approximately a third of patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, a stereotypical example of a mitochondrial disorder leading to a cardiomyopathy. We performed unique comparative ultrastructural and gene expression in a MELAS heart compared with non-failing controls. Our results showed a remarkable increase in mitochondrial inclusions and increased abnormal mitochondria in MELAS cardiomyopathy coupled with variable sarcomere thickening, heterogeneous distribution of affected cardiomyocytes and a greater elevation in the expression of disease markers. Investigation and management of patients with mitochondrial cardiomyopathy should follow the well-described contemporary heart failure clinical practice guidelines and include an important role of medical and device therapies. Directed metabolic therapy is lacking, but current research strategies are dedicated toward improving mitochondrial function in patients with mitochondrial disorders.

Herba Cistanches stimulates cellular glutathione redox cycling by reactive oxygen species generated from mitochondrial respiration in H9c2 cardiomyocytes.

PubMed

Wong, Hoi Shan; Ko, Kam Ming

2013-01-01

Earlier findings demonstrated that pretreatment of Herba Cistanches [the dried whole plant of Cistanche deserticola Y.C. Ma (Orobanchaceae)], a "Yang-invigorating" Chinese tonic herb, stimulated the ATP-generation capacity (ATP-GC) in mitochondria isolated from rat heart ex vivo. The enhancement of mitochondrial ATP-GC by Herba Cistanches was associated with induction of glutathione antioxidant status and protection against ischemia/reperfusion (I/R) injury in rat hearts. This study investigated the relationship between enhancements in mitochondrial ATP-GC and glutathione antioxidant status in H9c2 cardiomyocytes using a semipurified fraction of Herba Cistanches (HCF1). HCF1 (10-300 ng/mL) was tested for its effects on mitochondrial ATP generation, glutathione antioxidant status and protection against oxidant injury in H9c2 cardiomyocytes and rat hearts. HCF1 at 30 ng/mL increased mitochondrial ATP-GC and ADP-stimulated state 3 respiration (by 50 and 100%, respectively) in H9c2 cardiomyocytes. The stimulation of mitochondrial respiration was associated with the induction of mitochondrial uncoupling (27%) and enhancement of cellular glutathione redox cycling as well as protection against hypoxia/reoxygenation (hypox/reoxy)-induced apoptosis (by 60%). While HCF1 treatment increased reactive oxygen species generation from mitochondrial respiration in H9c2 cardiomyocytes, pretreatment with antioxidants (DMTU) abrogated the HCF1-induced cellular responses and the associated cytoprotective effect. HCF1 pretreatment (1.14 and 3.41 mg/kg × 14) also protected against myocardial I/R injury in rats (by 13 and 32%), presumably mediated by the induction of glutathione antioxidant response. The long-term intake of HCF1 may offer a prospect for the prevention of ischemic heart disease.

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics inmore » oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. - Highlights: • Demonstrated first time the link between the mPTP to mitochondrial dynamics. • The role of Cyclophilin D in the regulation of Drp1-mediated mitochondrial fission. • CsA as a potential target for governing oxidative stress related neuropathology.« less

Din7 and Mhr1 expression levels regulate double-strand-break-induced replication and recombination of mtDNA at ori5 in yeast.

PubMed

Ling, Feng; Hori, Akiko; Yoshitani, Ayako; Niu, Rong; Yoshida, Minoru; Shibata, Takehiko

2013-06-01

The Ntg1 and Mhr1 proteins initiate rolling-circle mitochondrial (mt) DNA replication to achieve homoplasmy, and they also induce homologous recombination to maintain mitochondrial genome integrity. Although replication and recombination profoundly influence mitochondrial inheritance, the regulatory mechanisms that determine the choice between these pathways remain unknown. In Saccharomyces cerevisiae, double-strand breaks (DSBs) introduced by Ntg1 at the mitochondrial replication origin ori5 induce homologous DNA pairing by Mhr1, and reactive oxygen species (ROS) enhance production of DSBs. Here, we show that a mitochondrial nuclease encoded by the nuclear gene DIN7 (DNA damage inducible gene) has 5'-exodeoxyribonuclease activity. Using a small ρ(-) mtDNA bearing ori5 (hypersuppressive; HS) as a model mtDNA, we revealed that DIN7 is required for ROS-enhanced mtDNA replication and recombination that are both induced at ori5. Din7 overproduction enhanced Mhr1-dependent mtDNA replication and increased the number of residual DSBs at ori5 in HS-ρ(-) cells and increased deletion mutagenesis at the ori5 region in ρ(+) cells. However, simultaneous overproduction of Mhr1 suppressed all of these phenotypes and enhanced homologous recombination. Our results suggest that after homologous pairing, the relative activity levels of Din7 and Mhr1 modulate the preference for replication versus homologous recombination to repair DSBs at ori5.

p21{sup WAF1/CIP1} deficiency induces mitochondrial dysfunction in HCT116 colon cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ae Jeong; Jee, Hye Jin; Song, Naree

2013-01-11

Highlights: Black-Right-Pointing-Pointer p21{sup -/-} HCT116 cells exhibited an increase in mitochondrial mass. Black-Right-Pointing-Pointer The expression levels of PGC-1{alpha} and AMPK were upregulated in p21{sup -/-} HCT116 cells. Black-Right-Pointing-Pointer The proliferation of p21{sup -/-} HCT116 cells in galactose medium was significantly impaired. Black-Right-Pointing-Pointer p21 may play a role in maintaining proper mitochondrial mass and respiratory function. -- Abstract: p21{sup WAF1/CIP1} is a critical regulator of cell cycle progression. However, the role of p21 in mitochondrial function remains poorly understood. In this study, we examined the effect of p21 deficiency on mitochondrial function in HCT116 human colon cancer cells. We found thatmore » there was a significant increase in the mitochondrial mass of p21{sup -/-} HCT116 cells, as measured by 10-N-nonyl-acridine orange staining, as well as an increase in the mitochondrial DNA content. In contrast, p53{sup -/-} cells had a mitochondrial mass comparable to that of wild-type HCT116 cells. In addition, the expression levels of the mitochondrial biogenesis regulators PGC-1{alpha} and TFAM and AMPK activity were also elevated in p21{sup -/-} cells, indicating that p21 deficiency induces the rate of mitochondrial biogenesis through the AMPK-PGC-1{alpha} axis. However, the increase in mitochondrial biogenesis in p21{sup -/-} cells did not accompany an increase in the cellular steady-state level of ATP. Furthermore, p21{sup -/-} cells exhibited significant proliferation impairment in galactose medium, suggesting that p21 deficiency induces a defect in the mitochondrial respiratory chain in HCT116 cells. Taken together, our results suggest that the loss of p21 results in an aberrant increase in the mitochondrial mass and in mitochondrial dysfunction in HCT116 cells, indicating that p21 is required to maintain proper mitochondrial mass and respiratory function.« less

Impaired Cerebral Mitochondrial Oxidative Phosphorylation Function in a Rat Model of Ventricular Fibrillation and Cardiopulmonary Resuscitation

PubMed Central

Fu, Yue; Xu, Wen; Jiang, Longyuan; Huang, Zitong

2014-01-01

Postcardiac arrest brain injury significantly contributes to mortality and morbidity in patients suffering from cardiac arrest (CA). Evidence that shows that mitochondrial dysfunction appears to be a key factor in tissue damage after ischemia/reperfusion is accumulating. However, limited data are available regarding the cerebral mitochondrial dysfunction during CA and cardiopulmonary resuscitation (CPR) and its relationship to the alterations of high-energy phosphate. Here, we sought to identify alterations of mitochondrial morphology and oxidative phosphorylation function as well as high-energy phosphates during CA and CPR in a rat model of ventricular fibrillation (VF). We found that impairment of mitochondrial respiration and partial depletion of adenosine triphosphate (ATP) and phosphocreatine (PCr) developed in the cerebral cortex and hippocampus following a prolonged cardiac arrest. Optimal CPR might ameliorate the deranged phosphorus metabolism and preserve mitochondrial function. No obvious ultrastructural abnormalities of mitochondria have been found during CA. We conclude that CA causes cerebral mitochondrial dysfunction along with decay of high-energy phosphates, which would be mitigated with CPR. This study may broaden our understanding of the pathogenic processes underlying global cerebral ischemic injury and provide a potential therapeutic strategy that aimed at preserving cerebral mitochondrial function during CA. PMID:24696844

Glutaredoxin-2 controls cardiac mitochondrial dynamics and energetics in mice, and protects against human cardiac pathologies.

PubMed

Kanaan, Georges N; Ichim, Bianca; Gharibeh, Lara; Maharsy, Wael; Patten, David A; Xuan, Jian Ying; Reunov, Arkadiy; Marshall, Philip; Veinot, John; Menzies, Keir; Nemer, Mona; Harper, Mary-Ellen

2018-04-01

Glutaredoxin 2 (GRX2), a mitochondrial glutathione-dependent oxidoreductase, is central to glutathione homeostasis and mitochondrial redox, which is crucial in highly metabolic tissues like the heart. Previous research showed that absence of Grx2, leads to impaired mitochondrial complex I function, hypertension and cardiac hypertrophy in mice but the impact on mitochondrial structure and function in intact cardiomyocytes and in humans has not been explored. We hypothesized that Grx2 controls cardiac mitochondrial dynamics and function in cellular and mouse models, and that low expression is associated with human cardiac dysfunction. Here we show that Grx2 absence impairs mitochondrial fusion, ultrastructure and energetics in primary cardiomyocytes and cardiac tissue. Moreover, provision of the glutathione precursor, N-acetylcysteine (NAC) to Grx2-/- mice did not restore glutathione redox or prevent impairments. Using genetic and histopathological data from the human Genotype-Tissue Expression consortium we demonstrate that low GRX2 is associated with fibrosis, hypertrophy, and infarct in the left ventricle. Altogether, GRX2 is important in the control of cardiac mitochondrial structure and function, and protects against human cardiac pathologies. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Tongluo Xingnao Effervescent Tablet preserves mitochondrial energy metabolism and attenuates cognition deficits in APPswe/PS1De9 mice.

PubMed

Dai, Yuan; Ma, Tao; Ren, Xiangyi; Wei, Jiangping; Fu, Wenjun; Ma, Yuntong; Xu, Shijun; Zhang, Zhanjun

2016-09-06

Tongluo Xingnao Effervescent Tablet (TXET), a traditional Chinese herbal formula composed of Ligusticum chuanxiong hor, Scutellaria baicalensis Georgi and Angelica sinensis, has been widely used to treat Alzheimer's disease (AD) and related dementias for decades in China. In the present study, we investigated the effects of TXET on mitochondrial function, energy metabolism and cognitive amelioration in the APPswe/PS1De9 transgenetic mouse model of AD. The energy charge and phosphocreatine, activity of the mitochondrial electron transport chain complexes, mitochondrial membrane potential, activity of Na(+)-K(+) ATPase and the expression levels of Bcl-2 and Bax in the brains were measured, respectively. TXET exhibits significant protection on mitochondrial function and energy supply in addition to ameliorating cognitive decline in APPswe/PS1De9 mice. TXET rescues mitochondrial function by increasing the mitochondrial membrane potential, energy charge levels, activity of respiratory chain complexes and Na(+)-K(+) ATPase activity. These findings suggest that TXET may attenuate cognition impairment through the restoration of mitochondrial function and energy metabolism in the brains in APPswe/PS1De9 mice. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mitochondrial functions of RECQL4 are required for the prevention of aerobic glycolysis-dependent cell invasion.

PubMed

Kumari, Jyoti; Hussain, Mansoor; De, Siddharth; Chandra, Suruchika; Modi, Priyanka; Tikoo, Shweta; Singh, Archana; Sagar, Chandrasekhar; Sepuri, Naresh Babu V; Sengupta, Sagar

2016-04-01

Germline mutations in RECQL4 helicase are associated with Rothmund-Thomson syndrome, which is characterized by a predisposition to cancer. RECQL4 localizes to the mitochondria, where it acts as an accessory factor during mitochondrial DNA replication. To understand the specific mitochondrial functions of RECQL4, we created isogenic cell lines, in which the mitochondrial localization of the helicase was either retained or abolished. The mitochondrial integrity was affected due to the absence of RECQL4 in mitochondria, leading to a decrease in F1F0-ATP synthase activity. In cells where RECQL4 does not localize to mitochondria, the membrane potential was decreased, whereas ROS levels increased due to the presence of high levels of catalytically inactive SOD2. Inactive SOD2 accumulated owing to diminished SIRT3 activity. Lack of the mitochondrial functions of RECQL4 led to aerobic glycolysis that, in turn, led to an increased invasive capability within these cells. Together, this study demonstrates for the first time that, owing to its mitochondrial functions, the accessory mitochondrial replication helicase RECQL4 prevents the invasive step in the neoplastic transformation process. © 2016. Published by The Company of Biologists Ltd.

Cord blood-derived CD34+ hematopoietic cells with low mitochondrial mass are enriched in hematopoietic repopulating stem cell function.

PubMed

Romero-Moya, Damia; Bueno, Clara; Montes, Rosa; Navarro-Montero, Oscar; Iborra, Francisco J; López, Luis Carlos; Martin, Miguel; Menendez, Pablo

2013-07-01

The homeostasis of the hematopoietic stem/progenitor cell pool relies on a fine-tuned balance between self-renewal, differentiation and proliferation. Recent studies have proposed that mitochondria regulate these processes. Although recent work has contributed to understanding the role of mitochondria during stem cell differentiation, it remains unclear whether the mitochondrial content/function affects human hematopoietic stem versus progenitor function. We found that mitochondrial mass correlates strongly with mitochondrial membrane potential in CD34(+) hematopoietic stem/progenitor cells. We, therefore, sorted cord blood CD34(+) cells on the basis of their mitochondrial mass and analyzed the in vitro homeostasis and clonogenic potential as well as the in vivo repopulating potential of CD34(+) cells with high (CD34(+) Mito(High)) versus low (CD34(+) Mito(Low)) mitochondrial mass. The CD34(+) Mito(Low) fraction contained 6-fold more CD34(+)CD38(-) primitive cells and was enriched in hematopoietic stem cell function, as demonstrated by its significantly greater hematopoietic reconstitution potential in immuno-deficient mice. In contrast, the CD34(+) Mito(High) fraction was more enriched in hematopoietic progenitor function with higher in vitro clonogenic capacity. In vitro differentiation of CD34(+) Mito(Low) cells was significantly delayed as compared to that of CD34(+) Mito(High) cells. The eventual complete differentiation of CD34(+) Mito(Low) cells, which coincided with a robust expansion of the CD34(-) differentiated progeny, was accompanied by mitochondrial adaptation, as shown by significant increases in ATP production and expression of the mitochondrial genes ND1 and COX2. In conclusion, cord blood CD34(+) cells with low levels of mitochondrial mass are enriched in hematopoietic repopulating stem cell function whereas high levels of mitochondrial mass identify hematopoietic progenitors. A mitochondrial response underlies hematopoietic stem/progenitor cell differentiation and proliferation of lineage-committed CD34(-) cells.

Integrative Identification of Arabidopsis Mitochondrial Proteome and Its Function Exploitation through Protein Interaction Network

PubMed Central

Cui, Jian; Liu, Jinghua; Li, Yuhua; Shi, Tieliu

2011-01-01

Mitochondria are major players on the production of energy, and host several key reactions involved in basic metabolism and biosynthesis of essential molecules. Currently, the majority of nucleus-encoded mitochondrial proteins are unknown even for model plant Arabidopsis. We reported a computational framework for predicting Arabidopsis mitochondrial proteins based on a probabilistic model, called Naive Bayesian Network, which integrates disparate genomic data generated from eight bioinformatics tools, multiple orthologous mappings, protein domain properties and co-expression patterns using 1,027 microarray profiles. Through this approach, we predicted 2,311 candidate mitochondrial proteins with 84.67% accuracy and 2.53% FPR performances. Together with those experimental confirmed proteins, 2,585 mitochondria proteins (named CoreMitoP) were identified, we explored those proteins with unknown functions based on protein-protein interaction network (PIN) and annotated novel functions for 26.65% CoreMitoP proteins. Moreover, we found newly predicted mitochondrial proteins embedded in particular subnetworks of the PIN, mainly functioning in response to diverse environmental stresses, like salt, draught, cold, and wound etc. Candidate mitochondrial proteins involved in those physiological acitivites provide useful targets for further investigation. Assigned functions also provide comprehensive information for Arabidopsis mitochondrial proteome. PMID:21297957

Impaired adenosine monophosphate-activated protein kinase signalling in dorsal root ganglia neurons is linked to mitochondrial dysfunction and peripheral neuropathy in diabetes

PubMed Central

Smith, Darrell R.; Saleh, Ali; Schapansky, Jason; Marquez, Alexandra; Gomes, Suzanne; Akude, Eli; Morrow, Dwane; Calcutt, Nigel A.; Fernyhough, Paul

2012-01-01

Mitochondrial dysfunction occurs in sensory neurons and may contribute to distal axonopathy in animal models of diabetic neuropathy. The adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) signalling axis senses the metabolic demands of cells and regulates mitochondrial function. Studies in muscle, liver and cardiac tissues have shown that the activity of adenosine monophosphate-activated protein kinase and PGC-1α is decreased under hyperglycaemia. In this study, we tested the hypothesis that deficits in adenosine monophosphate-activated protein kinase/PGC-1α signalling in sensory neurons underlie impaired axonal plasticity, suboptimal mitochondrial function and development of neuropathy in rodent models of type 1 and type 2 diabetes. Phosphorylation and expression of adenosine monophosphate-activated protein kinase/PGC-1α and mitochondrial respiratory chain complex proteins were downregulated in dorsal root ganglia of both streptozotocin-diabetic rats and db/db mice. Adenoviral-mediated manipulation of endogenous adenosine monophosphate-activated protein kinase activity using mutant proteins modulated neurotrophin-directed neurite outgrowth in cultures of sensory neurons derived from adult rats. Addition of resveratrol to cultures of sensory neurons derived from rats after 3–5 months of streptozotocin-induced diabetes, significantly elevated adenosine monophosphate-activated protein kinase levels, enhanced neurite outgrowth and normalized mitochondrial inner membrane polarization in axons. The bioenergetics profile (maximal oxygen consumption rate, coupling efficiency, respiratory control ratio and spare respiratory capacity) was aberrant in cultured sensory neurons from streptozotocin-diabetic rats and was corrected by resveratrol treatment. Finally, resveratrol treatment for the last 2 months of a 5-month period of diabetes reversed thermal hypoalgesia and attenuated foot skin intraepidermal nerve fibre loss and reduced myelinated fibre mean axonal calibre in streptozotocin-diabetic rats. These data suggest that the development of distal axonopathy in diabetic neuropathy is linked to nutrient excess and mitochondrial dysfunction via defective signalling of the adenosine monophosphate-activated protein kinase/PGC-1α pathway. PMID:22561641

Ubiquinol-10 Supplementation Activates Mitochondria Functions to Decelerate Senescence in Senescence-Accelerated Mice

PubMed Central

Tian, Geng; Sawashita, Jinko; Kubo, Hiroshi; Nishio, Shin-ya; Hashimoto, Shigenari; Suzuki, Nobuyoshi; Yoshimura, Hidekane; Tsuruoka, Mineko; Wang, Yaoyong; Liu, Yingye; Luo, Hongming; Xu, Zhe; Mori, Masayuki; Kitano, Mitsuaki; Hosoe, Kazunori; Takeda, Toshio; Usami, Shin-ichi

2014-01-01

Abstract Aim: The present study was conducted to define the relationship between the anti-aging effect of ubiquinol-10 supplementation and mitochondrial activation in senescence-accelerated mouse prone 1 (SAMP1) mice. Results: Here, we report that dietary supplementation with ubiquinol-10 prevents age-related decreases in the expression of sirtuin gene family members, which results in the activation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a major factor that controls mitochondrial biogenesis and respiration, as well as superoxide dismutase 2 (SOD2) and isocitrate dehydrogenase 2 (IDH2), which are major mitochondrial antioxidant enzymes. Ubiquinol-10 supplementation can also increase mitochondrial complex I activity and decrease levels of oxidative stress markers, including protein carbonyls, apurinic/apyrimidinic sites, malondialdehydes, and increase the reduced glutathione/oxidized glutathione ratio. Furthermore, ubiquinol-10 may activate Sirt1 and PGC-1α by increasing cyclic adenosine monophosphate (cAMP) levels that, in turn, activate cAMP response element-binding protein (CREB) and AMP-activated protein kinase (AMPK). Innovation and Conclusion: These results show that ubiquinol-10 may enhance mitochondrial activity by increasing levels of SIRT1, PGC-1α, and SIRT3 that slow the rate of age-related hearing loss and protect against the progression of aging and symptoms of age-related diseases. Antioxid. Redox Signal. 20, 2606–2620 PMID:24124769

Biochemical and bioinformatic analysis of the MYO19 motor domain

PubMed Central

Adikes, Rebecca C.; Unrath, William C.; Yengo, Christopher M.; Quintero, Omar A.

2014-01-01

Mitochondrial dynamics are dependent on both the microtubule and actin cytoskeletal systems. Evidence for the involvement of myosin motors has been described in many systems, and until recently a candidate mitochondrial transport motor had not been described in vertebrates. Myosin-XIX (MYO19) was predicted to represent a novel class of myosin and had previously been shown to bind to mitochondria and increase mitochondrial network dynamics when ectopically expressed. Our analyses comparing ∼40 MYO19 orthologs to ∼2000 other myosin motor domain sequences identified instances of homology well-conserved within class XIX myosins that were not found in other myosin classes, suggesting MYO19-specific mechanochemistry. Steady-state biochemical analyses of the MYO19 motor domain indicate that Homo sapiens MYO19 is a functional motor. Insect cell-expressed constructs bound calmodulin as a light chain at the predicted stoichiometry and displayed actin-activated ATPase activity. MYO19 constructs demonstrated high actin affinity in the presence of ATP in actin-cosedimentation assays, and translocated actin filaments in gliding assays. Expression of GFP-MYO19 containing a mutation impairing ATPase activity did not enhance mitochondrial network dynamics, as occurs with wild-type MYO19, indicating that myosin motor activity is required for mitochondrial motility. The measured biochemical properties of MYO19 suggest it is a high-duty ratio motor that could serve to transport mitochondria or anchor mitochondria, depending upon the cellular microenvironment. PMID:23568824

Monitoring Mitochondrial Electron Fluxes Using NAD(P)H-Flavoprotein Fluorometry Reveals Complex Action of Isoflurane on Cardiomyocytes

PubMed Central

Sedlic, Filip; Pravdic, Danijel; Hirata, Naoyuki; Mio, Yasushi; Sepac, Ana; Camara, Amadou K.; Wakatsuki, Tetsuro; Bosnjak, Zeljko J.; Bienengraeber, Martin

2010-01-01

Mitochondrial bioenergetic studies mostly rely on isolated mitochondria thus excluding the regulatory role of other cellular compartments important for the overall mitochondrial function. In intact cardiomyocytes, we followed the dynamics of electron fluxes along specific sites of the electron transport chain (ETC) by simultaneous detection of NAD(H)P and flavoprotein (FP) fluorescence intensities using a laser-scanning confocal microscope. This method was used to delineate the effects of isoflurane, a volatile anesthetic and cardioprotective agent, on the ETC. Comparison to the effects of well-characterized ETC inhibitors and uncoupling agent revealed two distinct effects of isoflurane: uncoupling-induced mitochondrial depolarization and inhibition of ETC at the level of complex I. In correlation, oxygen consumption measurements in cardiomyocytes confirmed a dose-dependent, dual effect of isoflurane, and in isolated mitochondria an obstruction of the ETC primarily at the level of complex I. These effects are likely responsible for the reported mild stimulation of mitochondrial reactive oxygen species (ROS) production required for the cardioprotective effects of isoflurane. In conclusion, isoflurane exhibits complex effects on the ETC in intact cardiomyocytes, altering its electron fluxes, and thereby enhancing ROS production. The NAD(P)H-FP fluorometry is a useful method for exploring the effect of drugs on mitochondria and identifying their specific sites of action within the ETC of intact cardiomyocytes. PMID:20646994

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells.

PubMed

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi; Ren, Yanming; Yu, Haiyang; You, Chao

2017-01-29

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics in oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial respiratory efficiency is positively correlated with human sperm motility.

PubMed

Ferramosca, Alessandra; Provenzano, Sara Pinto; Coppola, Lamberto; Zara, Vincenzo

2012-04-01

To correlate sperm mitochondrial respiratory efficiency with variations in sperm motility and with sperm morphologic anomalies. Sperm mitochondrial respiratory activity was evaluated with a polarographic assay of oxygen consumption carried out in hypotonically-treated sperm cells. A possible relationship among sperm mitochondrial respiratory efficiency, sperm motility, and morphologic anomalies was investigated. Mitochondrial respiratory efficiency was positively correlated with sperm motility and negatively correlated with the percentage of immotile spermatozoa. Moreover, midpiece defects impaired mitochondrial functionality. Our data indicate that an increase in sperm motility requires a parallel increase in mitochondrial respiratory capacity, thereby supporting the fundamental role played by mitochondrial oxidative phosphorylation in sperm motility of normozoospermic subjects. These results are of physiopathological relevance because they suggest that disturbances of sperm mitochondrial function and of energy production could be responsible for asthenozoospermia. Copyright © 2012 Elsevier Inc. All rights reserved.

The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders

PubMed Central

Liao, Yajin; Dong, Yuan; Cheng, Jinbo

2017-01-01

The mitochondrial calcium uniporter (MCU)—a calcium uniporter on the inner membrane of mitochondria—controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP); however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders. PMID:28208618

Lack of β, β-carotene -9’, 10’-oxygenase 2 leads to hepatic mitochondrial dysfunction and cellular oxidative stress in mice

PubMed Central

Wu, Lei; Guo, Xin; Hartson, Steven D.; Davis, Mary Abby; He, Hui; Medeiros, Denis M.; Wang, Weiqun; Clarke, Stephen L.; Lucas, Edralin; Smith, Brenda J.; von Lintig, Johannes; Lin, Dingbo

2017-01-01

Scope β,β-carotene-9’,10’-dioxygenase 2 (BCO2) is a carotenoid cleavage enzyme localized to the inner mitochondrial membrane in mammals. This study was aimed to assess the impact of genetic ablation of BCO2 on hepatic oxidative stress through mitochondrial function in mice. Methods and Results Liver samples from 6 week old male BCO2−/− knockout (KO) and isogenic wild-type (WT) mice were subjected to proteomics and functional activity assays. Compared to the WT, KO mice consumed more food (by 18 %) yet displayed significantly lower body weight (by 12 %). Mitochondrial proteomic results demonstrated that loss of BCO2 was associated with quantitative changes of the mitochondrial proteome mainly shown by suppressed expression of enzymes and/or proteins involved in fatty acid β–oxidation, the tricarboxylic acid cycle, and the electron transport chain (ETC). The mitochondrial basal respiratory rate, proton leak, and ETC complex II capacity were significantly elevated in the livers of KO compared to WT mice. Moreover, elevated reactive oxygen species and increased mitochondrial protein carbonylation were also demonstrated in liver of KO mice. Conclusions Loss of BCO2 induces mitochondrial hyperactivation, mitochondrial stress and changes of the mitochondrial proteome, leading to mitochondrial energy insufficiency. BCO2 appears to be critical for proper hepatic mitochondrial function. PMID:27991717

A mitochondrial-focused genetic interaction map reveals a scaffold-like complex required for inner membrane organization in mitochondria

PubMed Central

Hoppins, Suzanne; Collins, Sean R.; Cassidy-Stone, Ann; Hummel, Eric; DeVay, Rachel M.; Lackner, Laura L.; Westermann, Benedikt; Schuldiner, Maya

2011-01-01

To broadly explore mitochondrial structure and function as well as the communication of mitochondria with other cellular pathways, we constructed a quantitative, high-density genetic interaction map (the MITO-MAP) in Saccharomyces cerevisiae. The MITO-MAP provides a comprehensive view of mitochondrial function including insights into the activity of uncharacterized mitochondrial proteins and the functional connection between mitochondria and the ER. The MITO-MAP also reveals a large inner membrane–associated complex, which we term MitOS for mitochondrial organizing structure, comprised of Fcj1/Mitofilin, a conserved inner membrane protein, and five additional components. MitOS physically and functionally interacts with both outer and inner membrane components and localizes to extended structures that wrap around the inner membrane. We show that MitOS acts in concert with ATP synthase dimers to organize the inner membrane and promote normal mitochondrial morphology. We propose that MitOS acts as a conserved mitochondrial skeletal structure that differentiates regions of the inner membrane to establish the normal internal architecture of mitochondria. PMID:21987634

Developmental regulation of mitochondrial biogenesis and function in the mouse mammary gland during a prolonged lactation cycle

USDA-ARS?s Scientific Manuscript database

The regulation of mitochondrial biogenesis and function in the lactating mammary cell is poorly understood. The goal of this study was to use proteomics to relate temporal changes in mammary cell mitochondrial function during lactation to changes in the proteins that make up this organelle. The hypo...

Testosterone Plus Low-Intensity Physical Training in Late Life Improves Functional Performance, Skeletal Muscle Mitochondrial Biogenesis, and Mitochondrial Quality Control in Male Mice

PubMed Central

Guo, Wen; Wong, Siu; Li, Michelle; Liang, Wentao; Liesa, Marc; Serra, Carlo; Jasuja, Ravi; Bartke, Andrzej; Kirkland, James L.; Shirihai, Orian; Bhasin, Shalender

2012-01-01

Testosterone supplementation increases muscle mass in older men but has not been shown to consistently improve physical function and activity. It has been hypothesized that physical exercise is required to induce the adaptations necessary for translation of testosterone-induced muscle mass gain into functional improvements. However, the effects of testosterone plus low intensity physical exercise training (T/PT) on functional performance and bioenergetics are unknown. In this pilot study, we tested the hypothesis that combined administration of T/PT would improve functional performance and bioenergetics in male mice late in life more than low-intensity physical training alone. 28-month old male mice were randomized to receive T/PT or vehicle plus physical training (V/PT) for 2 months. Compare to V/PT control, administration of T/PT was associated with improvements in muscle mass, grip strength, spontaneous physical movements, and respiratory activity. These changes were correlated with increased mitochondrial DNA copy number and expression of markers for mitochondrial biogenesis. Mice receiving T/PT also displayed increased expression of key elements for mitochondrial quality control, including markers for mitochondrial fission-and-fusion and mitophagy. Concurrently, mice receiving T/PT also displayed increased expression of markers for reduced tissue oxidative damage and improved muscle quality. Conclusion: Testosterone administered with low-intensity physical training improves grip strength, spontaneous movements, and respiratory activity. These functional improvements were associated with increased muscle mitochondrial biogenesis and improved mitochondrial quality control. PMID:23240002

Multi-Parametric Analysis and Modeling of Relationships between Mitochondrial Morphology and Apoptosis

PubMed Central

Reis, Yara; Wolf, Thomas; Brors, Benedikt; Hamacher-Brady, Anne; Eils, Roland; Brady, Nathan R.

2012-01-01

Mitochondria exist as a network of interconnected organelles undergoing constant fission and fusion. Current approaches to study mitochondrial morphology are limited by low data sampling coupled with manual identification and classification of complex morphological phenotypes. Here we propose an integrated mechanistic and data-driven modeling approach to analyze heterogeneous, quantified datasets and infer relations between mitochondrial morphology and apoptotic events. We initially performed high-content, multi-parametric measurements of mitochondrial morphological, apoptotic, and energetic states by high-resolution imaging of human breast carcinoma MCF-7 cells. Subsequently, decision tree-based analysis was used to automatically classify networked, fragmented, and swollen mitochondrial subpopulations, at the single-cell level and within cell populations. Our results revealed subtle but significant differences in morphology class distributions in response to various apoptotic stimuli. Furthermore, key mitochondrial functional parameters including mitochondrial membrane potential and Bax activation, were measured under matched conditions. Data-driven fuzzy logic modeling was used to explore the non-linear relationships between mitochondrial morphology and apoptotic signaling, combining morphological and functional data as a single model. Modeling results are in accordance with previous studies, where Bax regulates mitochondrial fragmentation, and mitochondrial morphology influences mitochondrial membrane potential. In summary, we established and validated a platform for mitochondrial morphological and functional analysis that can be readily extended with additional datasets. We further discuss the benefits of a flexible systematic approach for elucidating specific and general relationships between mitochondrial morphology and apoptosis. PMID:22272225

Metformin Reduces Hepatic Expression of SIRT3, the Mitochondrial Deacetylase Controlling Energy Metabolism

PubMed Central

Buler, Marcin; Aatsinki, Sanna-Mari; Izzi, Valerio; Hakkola, Jukka

2012-01-01

Metformin inhibits ATP production in mitochondria and this may be involved in the anti-hyperglycemic effects of the drug. Sirtuin 3 (SIRT3) is a mitochondrial protein deacetylase that regulates the function of the electron transport chain and maintains basal ATP yield. We hypothesized that metformin treatment could diminish mitochondrial ATP production through downregulation of SIRT3 expression. Glucagon and cAMP induced SIRT3 mRNA in mouse primary hepatocytes. Metformin prevented SIRT3 induction by glucagon. Moreover, metformin downregulated constitutive expression of SIRT3 in primary hepatocytes and in the liver in vivo. Estrogen related receptor alpha (ERRα) mediates regulation of Sirt3 gene by peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). ERRα mRNA expression was regulated in a similar manner as SIRT3 mRNA by glucagon, cAMP and metformin. However, a higher metformin concentration was required for downregulation of ERRα than SIRT3. ERRα siRNA attenuated PGC-1α mediated induction of SIRT3, but did not affect constitutive expression. Overexpression of the constitutively active form of AMP-activated protein kinase (AMPK) induced SIRT3 mRNA, indicating that the SIRT3 downregulation by metformin is not mediated by AMPK. Metformin reduced the hepatocyte ATP level. This effect was partially counteracted by SIRT3 overexpression. Furthermore, metformin decreased mitochondrial SIRT3 protein levels and this was associated with enhanced acetylation of several mitochondrial proteins. However, metformin increased mitochondrial mass in hepatocytes. Altogether, our results indicate that metformin attenuates mitochondrial expression of SIRT3 and suggest that this mechanism is involved in regulation of energy metabolism by metformin in the liver and may contribute to the therapeutic action of metformin. PMID:23166782

Adenosine Monophosphate-Activated Protein Kinase Abates Hyperglycaemia-Induced Neuronal Injury in Experimental Models of Diabetic Neuropathy: Effects on Mitochondrial Biogenesis, Autophagy and Neuroinflammation.

PubMed

Yerra, Veera Ganesh; Kumar, Ashutosh

2017-04-01

Impaired adenosine monophosphate kinase (AMPK) signalling under hyperglycaemic conditions is known to cause mitochondrial dysfunction in diabetic sensory neurons. Facilitation of AMPK signalling is previously reported to ameliorate inflammation and induce autophagic response in various complications related to diabetes. The present study assesses the role of AMPK activation on mitochondrial biogenesis, autophagy and neuroinflammation in experimental diabetic neuropathy (DN) using an AMPK activator (A769662). A769662 (15 and 30 mg/kg, i.p) was administered to Sprague-Dawley rats (250-270 g) for 2 weeks after 6 weeks of streptozotocin (STZ) injection (55 mg/kg, i.p.). Behavioural parameters (mechanical/thermal hyperalgesia) and functional characteristics (motor/sensory nerve conduction velocities (MNCV and SNCV) and sciatic nerve blood flow (NBF)) were assessed. For in vitro studies, Neuro2a (N2A) cells were incubated with 25 mM glucose to simulate high glucose condition and then studied for mitochondrial dysfunction and protein expression changes. STZ administration resulted in significant hyperglycaemia (>250 mg/dl) in rats. A769662 treatment significantly improved mechanical/thermal hyperalgesia threshold and enhanced MNCV, SNCV and NBF in diabetic animals. A769662 exposure normalised the mitochondrial superoxide production, membrane depolarisation and markedly increased neurite outgrowth of N2A cells. Further, AMPK activation also abolished the NF-κB-mediated neuroinflammation. A769662 treatment increased Thr-172 phosphorylation of AMPK results in stimulated PGC-1α-directed mitochondrial biogenesis and autophagy induction. Our study supports that compromised AMPK signalling in hyperglycaemic conditions causes defective mitochondrial biogenesis ultimately leading to neuronal dysfunction and associated deficits in DN and activation of AMPK can be developed as an attractive therapeutic strategy for the management of DN.

Cloning and characterization of full-length mouse thymidine kinase 2: the N-terminal sequence directs import of the precursor protein into mitochondria.

PubMed Central

Wang, L; Eriksson, S

2000-01-01

The subcellular localization of mitochondrial thymidine kinase (TK2) has been questioned, since no mitochondrial targeting sequences have been found in cloned human TK2 cDNAs. Here we report the cloning of mouse TK2 cDNA from a mouse full-length enriched cDNA library. The mouse TK2 cDNA codes for a protein of 270 amino acids, with a 40-amino-acid presumed N-terminal mitochondrial targeting signal. In vitro translation and translocation experiments with purified rat mitochondria confirmed that the N-terminal sequence directed import of the precursor TK2 into the mitochondrial matrix. A single 2.4 kb mRNA transcript was detected in most tissues examined, except in liver, where an additional shorter (1.0 kb) transcript was also observed. There was no correlation between the tissue distribution of TK2 activity and the expression of TK2 mRNA. Full-length mouse TK2 protein and two N-terminally truncated forms, one of which corresponds to the mitochondrial form of TK2 and a shorter form corresponding to the previously characterized recombinant human TK2, were expressed in Escherichia coli and affinity purified. All three forms of TK2 phosphorylated thymidine, deoxycytidine and 2'-deoxyuridine, but with different kinetic efficiencies. A number of cytostatic pyrimidine nucleoside analogues were also tested and shown to be good substrates for the various forms of TK2. The active form of full-length mouse TK2 was a dimer, as judged by Superdex 200 chromatography. These results enhance our understanding of the structure and function of TK2, and may help to explain the mitochondrial disorder, mitochondrial neurogastrointestinal encephalomyopathy. PMID:11023833

BDNF pathway is involved in the protective effects of SS-31 on isoflurane-induced cognitive deficits in aging mice.

PubMed

Wu, Jing; Zhang, Mingqiang; Li, Huihui; Sun, Xiaoru; Hao, Shuangying; Ji, Muhuo; Yang, Jianjun; Li, Kuanyu

2016-05-15

Mitochondrial dysfunction has been linked to the earliest pathogenesis of isoflurane-induced cognitive impairments in developing or aging mammalian brain. However, its molecular mechanism is poorly understood and a pharmacologic treatment to rapidly reverse mitochondrial dysfunction is lacking. Fifteen-month-old male C57BL/6 mice were exposed to isoflurane for two hours following intraperitoneal administration of mitochondrion-targeted peptide SS-31 or vehicle with 30min interval. The hippocampus was immediately removed for biochemical assays and mitochondria isolation after inhalation. Behavioral tests were evaluated by the open field test and fear conditioning test 24h after the experiment. We showed that cognitive deficits induced by exposure of the aging mice to isoflurane were accompanied by mitochondrial dysfunction in hippocampus due to loss of the enzymatic activity of complex I. This loss resulted in the increase of reactive oxygen species production, decrease of ATP production and mitochondrial membrane potential, and opening of mitochondrial permeability transition pore. Further, we provided evidence that the BDNF signaling pathway was involved in this process to regulate synaptic plasticity-related proteins, for instance, downregulation of synapsin 1, PSD-95 and p-CREB, and upregulation of NR2A, NR2B, CaMKIIα and CaMKIIβ. Of note, the isoflurane-induced cognitive deficits were rescued by SS-31 through reversal of mitochondrial dysfunction, which facilitated the regulation of BDNF signaling including the expression reversal of aforementioned important synaptic-signaling proteins in aging mice. Our data demonstrate that reversing mitochondrial dysfunction by SS-31 enhances BDNF signaling pathway and synaptic plasticity, and provides protective effects on cognitive function, thereby support the notion that SS-31 may have therapeutic benefits for elderly humans undertaking anesthesia. Copyright © 2016 Elsevier B.V. All rights reserved.

Shear stress-induced mitochondrial biogenesis decreases the release of microparticles from endothelial cells.

PubMed

Kim, Ji-Seok; Kim, Boa; Lee, Hojun; Thakkar, Sunny; Babbitt, Dianne M; Eguchi, Satoru; Brown, Michael D; Park, Joon-Young

2015-08-01

The concept of enhancing structural integrity of mitochondria has emerged as a novel therapeutic option for cardiovascular disease. Flow-induced increase in laminar shear stress is a potent physiological stimulant associated with exercise, which exerts atheroprotective effects in the vasculature. However, the effect of laminar shear stress on mitochondrial remodeling within the vascular endothelium and its related functional consequences remain largely unknown. Using in vitro and in vivo complementary studies, here, we report that aerobic exercise alleviates the release of endothelial microparticles in prehypertensive individuals and that these salutary effects are, in part, mediated by shear stress-induced mitochondrial biogenesis. Circulating levels of total (CD31(+)/CD42a(-)) and activated (CD62E(+)) microparticles released by endothelial cells were significantly decreased (∼40% for both) after a 6-mo supervised aerobic exercise training program in individuals with prehypertension. In cultured human endothelial cells, laminar shear stress reduced the release of endothelial microparticles, which was accompanied by an increase in mitochondrial biogenesis through a sirtuin 1 (SIRT1)-dependent mechanism. Resveratrol, a SIRT1 activator, treatment showed similar effects. SIRT1 knockdown using small-interfering RNA completely abolished the protective effect of shear stress. Disruption of mitochondrial integrity by either antimycin A or peroxisome proliferator-activated receptor-γ coactivator-1α small-interfering RNA significantly increased the number of total, and activated, released endothelial microparticles, and shear stress restored these back to basal levels. Collectively, these data demonstrate a critical role of endothelial mitochondrial integrity in preserving endothelial homeostasis. Moreover, prolonged laminar shear stress, which is systemically elevated during aerobic exercise in the vessel wall, mitigates endothelial dysfunction by promoting mitochondrial biogenesis. Copyright © 2015 the American Physiological Society.

Mitigating peroxynitrite mediated mitochondrial dysfunction in aged rat brain by mitochondria-targeted antioxidant MitoQ.

PubMed

Maiti, Arpan Kumar; Spoorthi, B C; Saha, Nimai Chandra; Panigrahi, Ashis Kumar

2018-05-17

Although reactive oxygen species mediated oxidative stress is a well-documented mechanism of aging, recent evidences indicate involvement of nitrosative stress in the same. As mitochondrial dysfunction is considered as one of the primary features of aging, the present study was designed to understand the involvement of nitrosative stress by studying the impact of a mitochondria-targeted antioxidant MitoQ, a peroxynitrite (ONOO - ) scavenger, on mitochondrial functions. Four groups of rats were included in this study: Group I: Young-6 months (-MitoQ), Group II: Aged-22 months (- MitoQ), Group III: Young-6 months (+ MitoQ), Group IV: Aged-22 months (+ MitoQ). The rats belonging to group III and IV were treated with oral administration of MitoQ (500 μM) daily through drinking water for 5 weeks. MitoQ efficiently suppressed synaptosomal lipid peroxidation and protein oxidation accompanied by diminution of nitrite production and protein bound 3-nitrotyrosine. MitoQ normalized enhanced caspase 3 and 9 activities in aged rat brains and efficiently reversed ONOO - mediated mitochondrial complex I and IV inhibition, restored mitochondrial ATP production and lowered mitochondrial membrane potential loss. To ascertain these findings, a mitochondrial in vitro model (iron/ascorbate) was used involving different free radical scavengers and anti-oxidants. MitoQ provided better protection compared to mercaptoethylguanidine, N-nitro-L-arginine-methyl ester and superoxide dismutase establishing the predominancy of ONOO - in the process compared to • NO and O 2 •- . These results clearly highlight the involvement of nitrosative stress in aging process with MitoQ having therapeutic potential to fight against ONOO - mediated aging deficits.

Increases in Intracellular Zinc Enhance Proliferative Signaling as well as Mitochondrial and Endolysosomal Activity in Human Melanocytes.

PubMed

Rudolf, Emil; Rudolf, Kamil

2017-01-01

Zinc (Zn) is an important microelement required by skin cells for a variety of biological processes. The role of Zn in melanocyte proliferation and homeostasis has to date not been investigated. Human dermal melanocytes were isolated from patients and their proliferative activity determined along with both total and labile Zn content. Subsequently, changes in proliferation as well as in Zn content were determined upon exposure of the dermal melanocytes to external Zn. Further in-depth analyses were undertaken aimed at measuring the expression of proliferation-related proteins (determined by immunoblotting and densitometry), as well as changes in mitochondrial biogenesis and membrane potential (assessed by fluorescence-based cellometry) along with endolysosomal activity (determined by spectrofluorimetrically-measured elevation in fluorescence of lysosomal-aimed non-fuorescent substrate). Human skin melanocytes accumulate externally added Zn, a process which dose-dependently enhances their injury or proliferative activity. Enhanced proliferation is accompanied by an increased expression of the proteins AKT3, ERK1/2, c-MYC and CYCD. In addition, Zn-enriched melanocytes exhibit enhanced mitochondrial biogenesis, with individual mitochondria possessing stabilized mitochondrial membrane potential as well as showing elevated ATP and superoxide levels. Moreover, upon external exposure, Zn enters lysosomes/melanosomes, the activity of which is stimulated along with the process of autophagy. The determination of the unique Zn-dependent stimulation of melanocytes and in particular the enhancement of the cells' mitochondrial as well as lysosomal/melanosomal activities may prove important in tracing the sequence of steps in the process of melanomagenesis. © 2017 The Author(s). Published by S. Karger AG, Basel.

Anaplerotic Triheptanoin Diet Enhances Mitochondrial Substrate Use to Remodel the Metabolome and Improve Lifespan, Motor Function, and Sociability in MeCP2-Null Mice

PubMed Central

Li, Qun; Degano, Alicia L.; Penati, Judith; Zhuo, Justin; Roe, Charles R.; Ronnett, Gabriele V.

2014-01-01

Rett syndrome (RTT) is an autism spectrum disorder (ASD) caused by mutations in the X-linked MECP2 gene that encodes methyl-CpG binding protein 2 (MeCP2). Symptoms range in severity and include psychomotor disabilities, seizures, ataxia, and intellectual disability. Symptom onset is between 6-18 months of age, a critical period of brain development that is highly energy-dependent. Notably, patients with RTT have evidence of mitochondrial dysfunction, as well as abnormal levels of the adipokines leptin and adiponectin, suggesting overall metabolic imbalance. We hypothesized that one contributor to RTT symptoms is energy deficiency due to defective nutrient substrate utilization by the TCA cycle. This energy deficit would lead to a metabolic imbalance, but would be treatable by providing anaplerotic substrates to the TCA cycle to enhance energy production. We show that dietary therapy with triheptanoin significantly increased longevity and improved motor function and social interaction in male mice hemizygous for Mecp2 knockout. Anaplerotic therapy in Mecp2 knockout mice also improved indicators of impaired substrate utilization, decreased adiposity, increased glucose tolerance and insulin sensitivity, decreased serum leptin and insulin, and improved mitochondrial morphology in skeletal muscle. Untargeted metabolomics of liver and skeletal muscle revealed increases in levels of TCA cycle intermediates with triheptanoin diet, as well as normalizations of glucose and fatty acid biochemical pathways consistent with the improved metabolic phenotype in Mecp2 knockout mice on triheptanoin. These results suggest that an approach using dietary supplementation with anaplerotic substrate is effective in improving symptoms and metabolic health in RTT. PMID:25299635

GRP75 upregulates clathrin-independent endocytosis through actin cytoskeleton reorganization mediated by the concurrent activation of Cdc42 and RhoA.

PubMed

Chen, Hang; Gao, Zhihui; He, Changzheng; Xiang, Rong; van Kuppevelt, Toin H; Belting, Mattias; Zhang, Sihe

2016-05-01

Therapeutic macromolecules are internalized into the cell by either clathrin-mediated endocytosis (CME) or clathrin-independent endocytosis (CIE). Although some chaperone proteins play an essential role in CME (e.g. Hsc70 in clathrin uncoating), relatively few of these proteins are functionally involved in CIE. We previously revealed a role for the mitochondrial chaperone protein GRP75 in heparan sulfate proteoglycan (HSPG)-mediated, membrane raft-associated macromolecule endocytosis. However, the mechanism underlying this process remains unclear. In this study, using a mitochondrial signal peptide-directed protein trafficking expression strategy, we demonstrate that wild-type GRP75 expression enhanced the uptakes of HSPG and CIE marker cholera toxin B subunit but impaired the uptake of CME marker transferrin. The endocytosis regulation function of GRP75 is largely mediated by its subcellular location in mitochondria and is essentially determined by its ATPase domain. Interestingly, the mitochondrial expression of GRP75 or its ATPase domain significantly stimulates increases in both RhoA and Cdc42 activation, remarkably induces stress fibers and enhances filopodia formation, which collectively results in the promotion of CIE, but the inhibition of CME. Furthermore, silencing of Cdc42 or RhoA impaired the ability of GRP75 overexpression to increase CIE. Therefore, these results suggest that endocytosis vesicle enrichment of GRP75 by mitochondria trafficking upregulates CIE through an actin cytoskeleton reorganization mechanism mediated by the concurrent activation of Cdc42 and RhoA. This finding provides novel insight into organelle-derived chaperone signaling and the regulation of different endocytosis pathways in cells. Copyright © 2016 Elsevier Inc. All rights reserved.

Transplantation of autologously derived mitochondria protects the heart from ischemia-reperfusion injury

PubMed Central

Masuzawa, Akihiro; Black, Kendra M.; Pacak, Christina A.; Ericsson, Maria; Barnett, Reanne J.; Drumm, Ciara; Seth, Pankaj; Bloch, Donald B.; Levitsky, Sidney; Cowan, Douglas B.

2013-01-01

Mitochondrial damage and dysfunction occur during ischemia and modulate cardiac function and cell survival significantly during reperfusion. We hypothesized that transplantation of autologously derived mitochondria immediately prior to reperfusion would ameliorate these effects. New Zealand White rabbits were used for regional ischemia (RI), which was achieved by temporarily snaring the left anterior descending artery for 30 min. Following 29 min of RI, autologously derived mitochondria (RI-mitochondria; 9.7 ± 1.7 × 106/ml) or vehicle alone (RI-vehicle) were injected directly into the RI zone, and the hearts were allowed to recover for 4 wk. Mitochondrial transplantation decreased (P < 0.05) creatine kinase MB, cardiac troponin-I, and apoptosis significantly in the RI zone. Infarct size following 4 wk of recovery was decreased significantly in RI-mitochondria (7.9 ± 2.9%) compared with RI-vehicle (34.2 ± 3.3%, P < 0.05). Serial echocardiograms showed that RI-mitochondria hearts returned to normal contraction within 10 min after reperfusion was started; however, RI-vehicle hearts showed persistent hypokinesia in the RI zone at 4 wk of recovery. Electrocardiogram and optical mapping studies showed that no arrhythmia was associated with autologously derived mitochondrial transplantation. In vivo and in vitro studies show that the transplanted mitochondria are evident in the interstitial spaces and are internalized by cardiomyocytes 2–8 h after transplantation. The transplanted mitochondria enhanced oxygen consumption, high-energy phosphate synthesis, and the induction of cytokine mediators and proteomic pathways that are important in preserving myocardial energetics, cell viability, and enhanced post-infarct cardiac function. Transplantation of autologously derived mitochondria provides a novel technique to protect the heart from ischemia-reperfusion injury. PMID:23355340

Elevated Mitochondrial Reactive Oxygen Species and Cellular Redox Imbalance in Human NADPH-Oxidase-Deficient Phagocytes

PubMed Central

Sundqvist, Martina; Christenson, Karin; Björnsdottir, Halla; Osla, Veronica; Karlsson, Anna; Dahlgren, Claes; Speert, David P.; Fasth, Anders; Brown, Kelly L.; Bylund, Johan

2017-01-01

Chronic granulomatous disease (CGD) is caused by mutations in genes that encode the NADPH-oxidase and result in a failure of phagocytic cells to produce reactive oxygen species (ROS) via this enzyme system. Patients with CGD are highly susceptible to infections and often suffer from inflammatory disorders; the latter occurs in the absence of infection and correlates with the spontaneous production of inflammatory cytokines. This clinical feature suggests that NADPH-oxidase-derived ROS are not required for, or may even suppress, inflammatory processes. Experimental evidence, however, implies that ROS are in fact required for inflammatory cytokine production. By using a myeloid cell line devoid of a functional NADPH-oxidase and primary CGD cells, we analyzed intracellular oxidants, signs of oxidative stress, and inflammatory cytokine production. Herein, we demonstrate that phagocytes lacking a functional NADPH-oxidase, namely primary CGD phagocytes and a gp91phox-deficient cell line, display elevated levels of ROS derived from mitochondria. Accordingly, these cells, despite lacking the major source of cellular ROS, display clear signs of oxidative stress, including an induced expression of antioxidants and altered oxidation of cell surface thiols. These observed changes in redox state were not due to abnormalities in mitochondrial mass or membrane integrity. Finally, we demonstrate that increased mitochondrial ROS enhanced phosphorylation of ERK1/2, and induced production of IL8, findings that correlate with previous observations of increased MAPK activation and inflammatory cytokine production in CGD cells. Our data show that elevated baseline levels of mitochondria-derived oxidants lead to the counter-intuitive observation that CGD phagocytes are under oxidative stress and have enhanced MAPK signaling, which may contribute to the elevated basal production of inflammatory cytokines and the sterile inflammatory manifestations in CGD. PMID:29375548

Mitochondrial Retroprocessing Promoted Functional Transfers of rpl5 to the Nucleus in Grasses.

PubMed

Wu, Zhiqiang; Sloan, Daniel B; Brown, Colin W; Rosenblueth, Mónica; Palmer, Jeffrey D; Ong, Han Chuan

2017-09-01

Functional gene transfers from the mitochondrion to the nucleus are ongoing in angiosperms and have occurred repeatedly for all 15 ribosomal protein genes, but it is not clear why some of these genes are transferred more often than others nor what the balance is between DNA- and RNA-mediated transfers. Although direct insertion of mitochondrial DNA into the nucleus occurs frequently in angiosperms, case studies of functional mitochondrial gene transfer have implicated an RNA-mediated mechanism that eliminates introns and RNA editing sites, which would otherwise impede proper expression of mitochondrial genes in the nucleus. To elucidate the mechanisms that facilitate functional gene transfers and the evolutionary dynamics of the coexisting nuclear and mitochondrial gene copies that are established during these transfers, we have analyzed rpl5 genes from 90 grasses (Poaceae) and related monocots. Multiple lines of evidence indicate that rpl5 has been functionally transferred to the nucleus at least three separate times in the grass family and that at least seven species have intact and transcribed (but not necessarily functional) copies in both the mitochondrion and nucleus. In two grasses, likely functional nuclear copies of rpl5 have been subject to recent gene conversion events via secondarily transferred mitochondrial copies in what we believe are the first described cases of mitochondrial-to-nuclear gene conversion. We show that rpl5 underwent a retroprocessing event within the mitochondrial genome early in the evolution of the grass family, which we argue predisposed the gene towards successful, DNA-mediated functional transfer by generating a "pre-edited" sequence. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Suppression of Arrhythmia by Enhancing Mitochondrial Ca2+ Uptake in Catecholaminergic Ventricular Tachycardia Models.

PubMed

Schweitzer, Maria K; Wilting, Fabiola; Sedej, Simon; Dreizehnter, Lisa; Dupper, Nathan J; Tian, Qinghai; Moretti, Alessandra; My, Ilaria; Kwon, Ohyun; Priori, Silvia G; Laugwitz, Karl-Ludwig; Storch, Ursula; Lipp, Peter; Breit, Andreas; Mederos Y Schnitzler, Michael; Gudermann, Thomas; Schredelseker, Johann

2017-12-01

Cardiovascular disease-related deaths frequently arise from arrhythmias, but treatment options are limited due to perilous side effects of commonly used antiarrhythmic drugs. Cardiac rhythmicity strongly depends on cardiomyocyte Ca 2+ handling and prevalent cardiac diseases are causally associated with perturbations in intracellular Ca 2+ handling. Therefore, intracellular Ca 2+ transporters are lead candidate structures for novel and safer antiarrhythmic therapies. Mitochondria and mitochondrial Ca 2+ transport proteins are important regulators of cardiac Ca 2+ handling. Here we evaluated the potential of pharmacological activation of mitochondrial Ca 2+ uptake for the treatment of cardiac arrhythmia. To this aim,we tested substances that enhance mitochondrial Ca 2+ uptake for their ability to suppress arrhythmia in a murine model for ryanodine receptor 2 (RyR2)-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT) in vitro and in vivo and in induced pluripotent stem cell-derived cardiomyocytes from a CPVT patient. In freshly isolated cardiomyocytes of RyR2 R4496C/WT mice efsevin, a synthetic agonist of the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane, prevented the formation of diastolic Ca 2+ waves and spontaneous action potentials. The antiarrhythmic effect of efsevin was abolished by blockade of the mitochondrial Ca 2+ uniporter (MCU), but could be reproduced using the natural MCU activator kaempferol. Both mitochondrial Ca 2+ uptake enhancers (MiCUps), efsevin and kaempferol, significantly reduced episodes of stress-induced ventricular tachycardia in RyR2 R4496C/WT mice in vivo and abolished diastolic, arrhythmogenic Ca 2+ events in human iPSC-derived cardiomyocytes.