Alteration in mitochondrial Ca(2+) uptake disrupts insulin signaling in hypertrophic cardiomyocytes.

PubMed

Gutiérrez, Tomás; Parra, Valentina; Troncoso, Rodrigo; Pennanen, Christian; Contreras-Ferrat, Ariel; Vasquez-Trincado, César; Morales, Pablo E; Lopez-Crisosto, Camila; Sotomayor-Flores, Cristian; Chiong, Mario; Rothermel, Beverly A; Lavandero, Sergio

2014-11-07

Cardiac hypertrophy is characterized by alterations in both cardiac bioenergetics and insulin sensitivity. Insulin promotes glucose uptake by cardiomyocytes and its use as a substrate for glycolysis and mitochondrial oxidation in order to maintain the high cardiac energy demands. Insulin stimulates Ca(2+) release from the endoplasmic reticulum, however, how this translates to changes in mitochondrial metabolism in either healthy or hypertrophic cardiomyocytes is not fully understood. In the present study we investigated insulin-dependent mitochondrial Ca(2+) signaling in normal and norepinephrine or insulin like growth factor-1-induced hypertrophic cardiomyocytes. Using mitochondrion-selective Ca(2+)-fluorescent probes we showed that insulin increases mitochondrial Ca(2+) levels. This signal was inhibited by the pharmacological blockade of either the inositol 1,4,5-triphosphate receptor or the mitochondrial Ca(2+) uniporter, as well as by siRNA-dependent mitochondrial Ca(2+) uniporter knockdown. Norepinephrine-stimulated cardiomyocytes showed a significant decrease in endoplasmic reticulum-mitochondrial contacts compared to either control or insulin like growth factor-1-stimulated cells. This resulted in a reduction in mitochondrial Ca(2+) uptake, Akt activation, glucose uptake and oxygen consumption in response to insulin. Blocking mitochondrial Ca(2+) uptake was sufficient to mimic the effect of norepinephrine-induced cardiomyocyte hypertrophy on insulin signaling. Mitochondrial Ca(2+) uptake is a key event in insulin signaling and metabolism in cardiomyocytes.

Bioenergetics of lung tumors: alteration of mitochondrial biogenesis and respiratory capacity.

PubMed

Bellance, N; Benard, G; Furt, F; Begueret, H; Smolková, K; Passerieux, E; Delage, J P; Baste, J M; Moreau, P; Rossignol, R

2009-12-01

Little is known on the metabolic profile of lung tumors and the reminiscence of embryonic features. Herein, we determined the bioenergetic profiles of human fibroblasts taken from lung epidermoid carcinoma (HLF-a) and fetal lung (MRC5). We also analysed human lung tumors and their surrounding healthy tissue from four patients with adenocarcinoma. On these different models, we measured functional parameters (cell growth rates in oxidative and glycolytic media, respiration, ATP synthesis and PDH activity) as well as compositional features (expression level of various energy proteins and upstream transcription factors). The results demonstrate that both the lung fetal and cancer cell lines produced their ATP predominantly by glycolysis, while oxidative phosphorylation was only capable of poor ATP delivery. This was explained by a decreased mitochondrial biogenesis caused by a lowered expression of PGC1alpha (as shown by RT-PCR and Western blot) and mtTFA. Consequently, the relative expression of glycolytic versus OXPHOS markers was high in these cells. Moreover, the re-activation of mitochondrial biogenesis with resveratrol induced cell death specifically in cancer cells. A consistent reduction of mitochondrial biogenesis and the subsequent alteration of respiratory capacity was also observed in lung tumors, associated with a lower expression level of bcl2. Our data give a better characterization of lung cancer cells' metabolic alterations which are essential for growth and survival. They designate mitochondrial biogenesis as a possible target for anti-cancer therapy.

Renal Oxidative Stress Induced by Long-Term Hyperuricemia Alters Mitochondrial Function and Maintains Systemic Hypertension

PubMed Central

Cristóbal-García, Magdalena; García-Arroyo, Fernando E.; Arellano-Buendía, Abraham S.; Madero, Magdalena; Rodríguez-Iturbe, Bernardo; Pedraza-Chaverrí, José; Zazueta, Cecilia; Johnson, Richard J.; Sánchez Lozada, Laura-Gabriela

2015-01-01

We addressed if oxidative stress in the renal cortex plays a role in the induction of hypertension and mitochondrial alterations in hyperuricemia. A second objective was to evaluate whether the long-term treatment with the antioxidant Tempol prevents renal oxidative stress, mitochondrial alterations, and systemic hypertension in this model. Long-term (11-12 weeks) and short-term (3 weeks) effects of oxonic acid induced hyperuricemia were studied in rats (OA, 750 mg/kg BW), OA+Allopurinol (AP, 150 mg/L drinking water), OA+Tempol (T, 15 mg/kg BW), or vehicle. Systolic blood pressure, renal blood flow, and vascular resistance were measured. Tubular damage (urine N-acetyl-β-D-glucosaminidase) and oxidative stress markers (lipid and protein oxidation) along with ATP levels were determined in kidney tissue. Oxygen consumption, aconitase activity, and uric acid were evaluated in isolated mitochondria from renal cortex. Short-term hyperuricemia resulted in hypertension without demonstrable renal oxidative stress or mitochondrial dysfunction. Long-term hyperuricemia induced hypertension, renal vasoconstriction, tubular damage, renal cortex oxidative stress, and mitochondrial dysfunction and decreased ATP levels. Treatments with Tempol and allopurinol prevented these alterations. Renal oxidative stress induced by hyperuricemia promoted mitochondrial functional disturbances and decreased ATP content, which represent an additional pathogenic mechanism induced by chronic hyperuricemia. Hyperuricemia-related hypertension occurs before these changes are evident. PMID:25918583

Constriction of the mitochondrial inner compartment is a priming event for mitochondrial division

PubMed Central

Cho, Bongki; Cho, Hyo Min; Jo, Youhwa; Kim, Hee Dae; Song, Myungjae; Moon, Cheil; Kim, Hyongbum; Kim, Kyungjin; Sesaki, Hiromi; Rhyu, Im Joo; Kim, Hyun; Sun, Woong

2017-01-01

Mitochondrial division is critical for the maintenance and regulation of mitochondrial function, quality and distribution. This process is controlled by cytosolic actin-based constriction machinery and dynamin-related protein 1 (Drp1) on mitochondrial outer membrane (OMM). Although mitochondrial physiology, including oxidative phosphorylation, is also important for efficient mitochondrial division, morphological alterations of the mitochondrial inner-membrane (IMM) have not been clearly elucidated. Here we report spontaneous and repetitive constriction of mitochondrial inner compartment (CoMIC) associated with subsequent division in neurons. Although CoMIC is potentiated by inhibition of Drp1 and occurs at the potential division spots contacting the endoplasmic reticulum, it appears on IMM independently of OMM. Intra-mitochondrial influx of Ca2+ induces and potentiates CoMIC, and leads to K+-mediated mitochondrial bulging and depolarization. Synergistically, optic atrophy 1 (Opa1) also regulates CoMIC via controlling Mic60-mediated OMM–IMM tethering. Therefore, we propose that CoMIC is a priming event for efficient mitochondrial division. PMID:28598422

Directed alteration of Saccharomyces cerevisiae mitochondrial DNA by biolistic transformation and homologous recombination.

PubMed

Bonnefoy, Nathalie; Fox, Thomas D

2007-01-01

Saccharomyces cerevisiae is currently the only species in which genetic transformation of mitochondria can be used to generate a wide variety of defined alterations in mitochondrial deoxyribonucleic acid (mtDNA). DNA sequences can be delivered into yeast mitochondria by microprojectile bombardment (biolistic transformation) and subsequently incorporated into mtDNA by the highly active homologous recombination machinery present in the organelle. Although transformation frequencies are relatively low, the availability of strong mitochondrial selectable markers for the yeast system, both natural and synthetic, makes the isolation of transformants routine. The strategies and procedures reviewed here allow the researcher to insert defined mutations into endogenous mitochondrial genes and to insert new genes into mtDNA. These methods provide powerful in vivo tools for the study of mitochondrial biology.

Altered Glycolysis and Mitochondrial Respiration in a Zebrafish Model of Dravet Syndrome.

PubMed

Kumar, Maneesh G; Rowley, Shane; Fulton, Ruth; Dinday, Matthew T; Baraban, Scott C; Patel, Manisha

2016-01-01

Altered metabolism is an important feature of many epileptic syndromes but has not been reported in Dravet syndrome (DS), a catastrophic childhood epilepsy associated with mutations in a voltage-activated sodium channel, Nav1.1 (SCN1A). To address this, we developed novel methodology to assess real-time changes in bioenergetics in zebrafish larvae between 4 and 6 d postfertilization (dpf). Baseline and 4-aminopyridine (4-AP) stimulated glycolytic flux and mitochondrial respiration were simultaneously assessed using a Seahorse Biosciences extracellular flux analyzer. Scn1Lab mutant zebrafish showed a decrease in baseline glycolytic rate and oxygen consumption rate (OCR) compared to controls. A ketogenic diet formulation rescued mutant zebrafish metabolism to control levels. Increasing neuronal excitability with 4-AP resulted in an immediate increase in glycolytic rates in wild-type zebrafish, whereas mitochondrial OCR increased slightly and quickly recovered to baseline values. In contrast, scn1Lab mutant zebrafish showed a significantly slower and exaggerated increase of both glycolytic rates and OCR after 4-AP. The underlying mechanism of decreased baseline OCR in scn1Lab mutants was not because of altered mitochondrial DNA content or dysfunction of enzymes in the electron transport chain or tricarboxylic acid cycle. Examination of glucose metabolism using a PCR array identified five glycolytic genes that were downregulated in scn1Lab mutant zebrafish. Our findings in scn1Lab mutant zebrafish suggest that glucose and mitochondrial hypometabolism contribute to the pathophysiology of DS.

Interleukin-15 Modulates Adipose Tissue by Altering Mitochondrial Mass and Activity

PubMed Central

Barra, Nicole G.; Palanivel, Rengasamy; Denou, Emmanuel; Chew, Marianne V.; Gillgrass, Amy; Walker, Tina D.; Kong, Josh; Richards, Carl D.; Jordana, Manel; Collins, Stephen M.; Trigatti, Bernardo L.; Holloway, Alison C.; Raha, Sandeep; Steinberg, Gregory R.; Ashkar, Ali A.

2014-01-01

Interleukin-15 (IL-15) is an immunomodulatory cytokine that affects body mass regulation independent of lymphocytes; however, the underlying mechanism(s) involved remains unknown. In an effort to investigate these mechanisms, we performed metabolic cage studies, assessed intestinal bacterial diversity and macronutrient absorption, and examined adipose mitochondrial activity in cultured adipocytes and in lean IL-15 transgenic (IL-15tg), overweight IL-15 deficient (IL-15−/−), and control C57Bl/6 (B6) mice. Here we show that differences in body weight are not the result of differential activity level, food intake, or respiratory exchange ratio. Although intestinal microbiota differences between obese and lean individuals are known to impact macronutrient absorption, differing gut bacteria profiles in these murine strains does not translate to differences in body weight in colonized germ free animals and macronutrient absorption. Due to its contribution to body weight variation, we examined mitochondrial factors and found that IL-15 treatment in cultured adipocytes resulted in increased mitochondrial membrane potential and decreased lipid deposition. Lastly, IL-15tg mice have significantly elevated mitochondrial activity and mass in adipose tissue compared to B6 and IL-15−/− mice. Altogether, these results suggest that IL-15 is involved in adipose tissue regulation and linked to altered mitochondrial function. PMID:25517731

Supplementation with Vitamin E and Vitamin C inversely alters mitochondrial copy number and mitochondrial protein in obese, exercising rats

USDA-ARS?s Scientific Manuscript database

Controversy exists as to whether supplementation with the antioxidants vitamin E (VE) and vitamin C (VC) blocks adaptation to exercise. Exercise is a first-line means to treat obesity and its complications. While obesity alters mitochondrial (MT) function and induces insulin resistance (IR), no data...

Mitochondrial gene polymorphisms alter hepatic cellular energy metabolism and aggravate diet-induced non-alcoholic steatohepatitis.

PubMed

Schröder, Torsten; Kucharczyk, David; Bär, Florian; Pagel, René; Derer, Stefanie; Jendrek, Sebastian Torben; Sünderhauf, Annika; Brethack, Ann-Kathrin; Hirose, Misa; Möller, Steffen; Künstner, Axel; Bischof, Julia; Weyers, Imke; Heeren, Jörg; Koczan, Dirk; Schmid, Sebastian Michael; Divanovic, Senad; Giles, Daniel Aaron; Adamski, Jerzy; Fellermann, Klaus; Lehnert, Hendrik; Köhl, Jörg; Ibrahim, Saleh; Sina, Christian

2016-04-01

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an enhanced risk for liver and cardiovascular diseases and mortality. NAFLD can progress from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH). However, the mechanisms predisposing to this progression remain undefined. Notably, hepatic mitochondrial dysfunction is a common finding in patients with NASH. Due to a lack of appropriate experimental animal models, it has not been evaluated whether this mitochondrial dysfunction plays a causative role for the development of NASH. To determine the effect of a well-defined mitochondrial dysfunction on liver physiology at baseline and during dietary challenge, C57BL/6J-mt(FVB/N) mice were employed. This conplastic inbred strain has been previously reported to exhibit decreased mitochondrial respiration likely linked to a non-synonymous gene variation (nt7778 G/T) of the mitochondrial ATP synthase protein 8 (mt-ATP8). At baseline conditions, C57BL/6J-mt(FVB/N) mice displayed hepatic mitochondrial dysfunction characterized by decreased ATP production and increased formation of reactive oxygen species (ROS). Moreover, genes affecting lipid metabolism were differentially expressed, hepatic triglyceride and cholesterol levels were changed in these animals, and various acyl-carnitines were altered, pointing towards an impaired mitochondrial carnitine shuttle. However, over a period of twelve months, no spontaneous hepatic steatosis or inflammation was observed. On the other hand, upon dietary challenge with either a methionine and choline deficient diet or a western-style diet, C57BL/6J-mt(FVB/N) mice developed aggravated steatohepatitis as characterized by lipid accumulation, ballooning of hepatocytes and infiltration of immune cells. We observed distinct metabolic alterations in mice with a mitochondrial polymorphism associated hepatic mitochondrial dysfunction. However, a second hit, such as dietary stress

Mitochondrial gene polymorphisms alter hepatic cellular energy metabolism and aggravate diet-induced non-alcoholic steatohepatitis

PubMed Central

Schröder, Torsten; Kucharczyk, David; Bär, Florian; Pagel, René; Derer, Stefanie; Jendrek, Sebastian Torben; Sünderhauf, Annika; Brethack, Ann-Kathrin; Hirose, Misa; Möller, Steffen; Künstner, Axel; Bischof, Julia; Weyers, Imke; Heeren, Jörg; Koczan, Dirk; Schmid, Sebastian Michael; Divanovic, Senad; Giles, Daniel Aaron; Adamski, Jerzy; Fellermann, Klaus; Lehnert, Hendrik; Köhl, Jörg; Ibrahim, Saleh; Sina, Christian

2016-01-01

Objective Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an enhanced risk for liver and cardiovascular diseases and mortality. NAFLD can progress from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH). However, the mechanisms predisposing to this progression remain undefined. Notably, hepatic mitochondrial dysfunction is a common finding in patients with NASH. Due to a lack of appropriate experimental animal models, it has not been evaluated whether this mitochondrial dysfunction plays a causative role for the development of NASH. Methods To determine the effect of a well-defined mitochondrial dysfunction on liver physiology at baseline and during dietary challenge, C57BL/6J-mtFVB/N mice were employed. This conplastic inbred strain has been previously reported to exhibit decreased mitochondrial respiration likely linked to a non-synonymous gene variation (nt7778 G/T) of the mitochondrial ATP synthase protein 8 (mt-ATP8). Results At baseline conditions, C57BL/6J-mtFVB/N mice displayed hepatic mitochondrial dysfunction characterized by decreased ATP production and increased formation of reactive oxygen species (ROS). Moreover, genes affecting lipid metabolism were differentially expressed, hepatic triglyceride and cholesterol levels were changed in these animals, and various acyl-carnitines were altered, pointing towards an impaired mitochondrial carnitine shuttle. However, over a period of twelve months, no spontaneous hepatic steatosis or inflammation was observed. On the other hand, upon dietary challenge with either a methionine and choline deficient diet or a western-style diet, C57BL/6J-mtFVB/N mice developed aggravated steatohepatitis as characterized by lipid accumulation, ballooning of hepatocytes and infiltration of immune cells. Conclusions We observed distinct metabolic alterations in mice with a mitochondrial polymorphism associated hepatic mitochondrial dysfunction. However, a

Mic60/Mitofilin Overexpression Alters Mitochondrial Dynamics and Attenuates Vulnerability of Dopaminergic Cells to Dopamine and Rotenone

PubMed Central

Van Laar, Victor S.; Berman, Sarah B.; Hastings, Teresa G.

2017-01-01

Mitochondrial dysfunction has been implicated in Parkinson’s disease (PD) neuropathology. Mic60, also known as mitofilin, is a protein of the inner mitochondrial membrane and a key component of the mitochondrial contact site and cristae junction organizing system (MICOS). Mic60 is critical for maintaining mitochondrial membrane structure and function. We previously demonstrated that mitochondrial Mic60 protein is susceptible to both covalent modification and loss in abundance following exposure to dopamine quinone. In this study, we utilized neuronally-differentiated SH-SY5Y and PC12 dopaminergic cell lines to examine the effects of altered Mic60 levels on mitochondrial function and cellular vulnerability in response to PD-relevant stressors. Short hairpin RNA (shRNA)-mediated knockdown of endogenous Mic60 protein in neuronal SH-SY5Y cells significantly potentiated dopamine-induced cell death, which was rescued by co-expressing shRNA-insensitive Mic60. Conversely, in PC12 and SH-SY5Y cells, Mic60 overexpression significantly attenuated both dopamine- and rotenone-induced cell death as compared to controls. Mic60 overexpression in SH-SY5Y cells was also associated with increased mitochondrial respiration, and, following rotenone exposure, increased spare respiratory capacity. Mic60 knockdown cells exhibited suppressed respiration and, following rotenone treatment, decreased spare respiratory capacity. Mic60 overexpression also affected mitochondrial fission/fusion dynamics. PC12 cells overexpressing Mic60 exhibited increased mitochondrial interconnectivity. Further, both PC12 cells and primary rat cortical neurons overexpressing Mic60 displayed suppressed mitochondrial fission and increased mitochondrial length in neurites. These results suggest that altering levels of Mic60 in dopaminergic neuronal cells significantly affects both mitochondrial homeostasis and cellular vulnerability to the PD-relevant stressors dopamine and rotenone, carrying implications for PD

Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages

PubMed Central

Fukasawa, Yoshinori; Oda, Toshiyuki; Tomii, Kentaro

2017-01-01

Abstract Protein transport systems are fundamentally important for maintaining mitochondrial function. Nevertheless, mitochondrial protein translocases such as the kinetoplastid ATOM complex have recently been shown to vary in eukaryotic lineages. Various evolutionary hypotheses have been formulated to explain this diversity. To resolve any contradiction, estimating the primitive state and clarifying changes from that state are necessary. Here, we present more likely primitive models of mitochondrial translocases, specifically the translocase of the outer membrane (TOM) and translocase of the inner membrane (TIM) complexes, using scrutinized phylogenetic profiles. We then analyzed the translocases’ evolution in eukaryotic lineages. Based on those results, we propose a novel evolutionary scenario for diversification of the mitochondrial transport system. Our results indicate that presequence transport machinery was mostly established in the last eukaryotic common ancestor, and that primitive translocases already had a pathway for transporting presequence-containing proteins. Moreover, secondary changes including convergent and migrational gains of a presequence receptor in TOM and TIM complexes, respectively, likely resulted from constrained evolution. The nature of a targeting signal can constrain alteration to the protein transport complex. PMID:28369657

Mitochondrial Optic Atrophy (OPA) 1 Processing Is Altered in Response to Neonatal Hypoxic-Ischemic Brain Injury

PubMed Central

Baburamani, Ana A.; Hurling, Chloe; Stolp, Helen; Sobotka, Kristina; Gressens, Pierre; Hagberg, Henrik; Thornton, Claire

2015-01-01

Perturbation of mitochondrial function and subsequent induction of cell death pathways are key hallmarks in neonatal hypoxic-ischemic (HI) injury, both in animal models and in term infants. Mitoprotective therapies therefore offer a new avenue for intervention for the babies who suffer life-long disabilities as a result of birth asphyxia. Here we show that after oxygen-glucose deprivation in primary neurons or in a mouse model of HI, mitochondrial protein homeostasis is altered, manifesting as a change in mitochondrial morphology and functional impairment. Furthermore we find that the mitochondrial fusion and cristae regulatory protein, OPA1, is aberrantly cleaved to shorter forms. OPA1 cleavage is normally regulated by a balanced action of the proteases Yme1L and Oma1. However, in primary neurons or after HI in vivo, protein expression of YmelL is also reduced, whereas no change is observed in Oma1 expression. Our data strongly suggest that alterations in mitochondria-shaping proteins are an early event in the pathogenesis of neonatal HI injury. PMID:26393574

Inhibition of the alpha-ketoglutarate dehydrogenase complex alters mitochondrial function and cellular calcium regulation.

PubMed

Huang, Hsueh-Meei; Zhang, Hui; Xu, Hui; Gibson, Gary E

2003-01-20

Mitochondrial dysfunction occurs in many neurodegenerative diseases. The alpha-ketoglutarate dehydrogenase complex (KGDHC) catalyzes a key and arguably rate-limiting step of the tricarboxylic acid cycle (TCA). A reduction in the activity of the KGDHC occurs in brains and cells of patients with many of these disorders and may underlie the abnormal mitochondrial function. Abnormalities in calcium homeostasis also occur in fibroblasts from Alzheimer's disease (AD) patients and in cells bearing mutations that lead to AD. Thus, the present studies test whether the reduction of KGDHC activity can lead to the alterations in mitochondrial function and calcium homeostasis. alpha-Keto-beta-methyl-n-valeric acid (KMV) inhibits KGDHC activity in living N2a cells in a dose- and time-dependent manner. Surprisingly, concentration of KMV that inhibit in situ KGDHC by 80% does not alter the mitochondrial membrane potential (MMP). However, similar concentrations of KMV induce the release of cytochrome c from mitochondria into the cytosol, reduce basal [Ca(2+)](i) by 23% (P<0.005), and diminish the bradykinin (BK)-induced calcium release from the endoplasmic reticulum (ER) by 46% (P<0.005). This result suggests that diminished KGDHC activities do not lead to the Ca(2+) abnormalities in fibroblasts from AD patients or cells bearing PS-1 mutations. The increased release of cytochrome c with diminished KGDHC activities will be expected to activate other pathways including cell death cascades. Reductions in this key mitochondrial enzyme will likely make the cells more vulnerable to metabolic insults that promote cell death.

Mitochondrial Dynamics in Mitochondrial Diseases

PubMed Central

Suárez-Rivero, Juan M.; Villanueva-Paz, Marina; de la Cruz-Ojeda, Patricia; de la Mata, Mario; Cotán, David; Oropesa-Ávila, Manuel; de Lavera, Isabel; Álvarez-Córdoba, Mónica; Luzón-Hidalgo, Raquel; Sánchez-Alcázar, José A.

2016-01-01

Mitochondria are very versatile organelles in continuous fusion and fission processes in response to various cellular signals. Mitochondrial dynamics, including mitochondrial fission/fusion, movements and turnover, are essential for the mitochondrial network quality control. Alterations in mitochondrial dynamics can cause neuropathies such as Charcot-Marie-Tooth disease in which mitochondrial fusion and transport are impaired, or dominant optic atrophy which is caused by a reduced mitochondrial fusion. On the other hand, mitochondrial dysfunction in primary mitochondrial diseases promotes reactive oxygen species production that impairs its own function and dynamics, causing a continuous vicious cycle that aggravates the pathological phenotype. Mitochondrial dynamics provides a new way to understand the pathophysiology of mitochondrial disorders and other diseases related to mitochondria dysfunction such as diabetes, heart failure, or Hungtinton’s disease. The knowledge about mitochondrial dynamics also offers new therapeutics targets in mitochondrial diseases. PMID:28933354

Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages.

PubMed

Fukasawa, Yoshinori; Oda, Toshiyuki; Tomii, Kentaro; Imai, Kenichiro

2017-07-01

Protein transport systems are fundamentally important for maintaining mitochondrial function. Nevertheless, mitochondrial protein translocases such as the kinetoplastid ATOM complex have recently been shown to vary in eukaryotic lineages. Various evolutionary hypotheses have been formulated to explain this diversity. To resolve any contradiction, estimating the primitive state and clarifying changes from that state are necessary. Here, we present more likely primitive models of mitochondrial translocases, specifically the translocase of the outer membrane (TOM) and translocase of the inner membrane (TIM) complexes, using scrutinized phylogenetic profiles. We then analyzed the translocases' evolution in eukaryotic lineages. Based on those results, we propose a novel evolutionary scenario for diversification of the mitochondrial transport system. Our results indicate that presequence transport machinery was mostly established in the last eukaryotic common ancestor, and that primitive translocases already had a pathway for transporting presequence-containing proteins. Moreover, secondary changes including convergent and migrational gains of a presequence receptor in TOM and TIM complexes, respectively, likely resulted from constrained evolution. The nature of a targeting signal can constrain alteration to the protein transport complex. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Alcohol alters hepatic FoxO1, p53, and mitochondrial SIRT5 deacetylation function

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

Lieber, Charles S.; Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029; Leo, Maria Anna

2008-08-22

Chronic alcohol consumption affects the gene expression of a NAD-dependent deacetylase Sirtuis 1 (SIRT1) and the peroxisome proliferator-activated receptor-{gamma} coactivator1{alpha} (PGC-1{alpha}). Our aim was to verify that it also alters the forkhead (FoxO1) and p53 transcription factor proteins, critical in the hepatic response to oxidative stress and regulated by SIRT1 through its deacetylating capacity. Accordingly, rats were pair-fed the Lieber-DeCarli alcohol-containing liquid diets for 28 days. Alcohol increased hepatic mRNA expression of FoxO1 (p = 0.003) and p53 (p = 0.001) while corresponding protein levels remained unchanged. However phospho-FoxO1 and phospho-Akt (protein kinase) were both decreased by alcohol consumption (pmore » = 0.04 and p = 0.02, respectively) while hepatic p53 was found hyperacetylated (p = 0.017). Furthermore, mitochondrial SIRT5 was reduced (p = 0.0025), and PGC-1{alpha} hyperacetylated (p = 0.027), establishing their role in protein modification. Thus, alcohol consumption disrupts nuclear-mitochondrial interactions by post-translation protein modifications, which contribute to alteration of mitochondrial biogenesis through the newly discovered reduction of SIRT5.« less

Short-term sleep deprivation with exposure to nocturnal light alters mitochondrial bioenergetics in Drosophila.

PubMed

Rodrigues, Nathane Rosa; Macedo, Giulianna Echeverria; Martins, Illana Kemmerich; Gomes, Karen Kich; de Carvalho, Nélson Rodrigues; Posser, Thaís; Franco, Jeferson Luis

2018-05-20

Many studies have shown the effects of sleep deprivation in several aspects of health and disease. However, little is known about how mitochondrial bioenergetics function is affected under this condition. To clarify this, we developed a simple model of short-term sleep deprivation, in which fruit-flies were submitted to a nocturnal light condition and then mitochondrial parameters were assessed by high resolution respirometry (HRR). Exposure of flies to constant light was able to alter sleep patterns, causing locomotor deficits, increasing ROS production and lipid peroxidation, affecting mitochondrial activity, antioxidant defense enzymes and caspase activity. HRR analysis showed that sleep deprivation affected mitochondrial bioenergetics capacity, decreasing respiration at oxidative phosphorylation (OXPHOS) and electron transport system (ETS). In addition, the expression of genes involved in the response to oxidative stress and apoptosis were increased. Thus, our results suggest a connection between sleep deprivation and oxidative stress, pointing to mitochondria as a possible target of this relationship. Copyright © 2018 Elsevier Inc. All rights reserved.

Myostatin induces mitochondrial metabolic alteration and typical apoptosis in cancer cells

PubMed Central

Liu, Y; Cheng, H; Zhou, Y; Zhu, Y; Bian, R; Chen, Y; Li, C; Ma, Q; Zheng, Q; Zhang, Y; Jin, H; Wang, X; Chen, Q; Zhu, D

2013-01-01

Myostatin, a member of the transforming growth factor-β superfamily, regulates the glucose metabolism of muscle cells, while dysregulated myostatin activity is associated with a number of metabolic disorders, including muscle cachexia, obesity and type II diabetes. We observed that myostatin induced significant mitochondrial metabolic alterations and prolonged exposure of myostatin induced mitochondria-dependent apoptosis in cancer cells addicted to glycolysis. To address the underlying mechanism, we found that the protein levels of Hexokinase II (HKII) and voltage-dependent anion channel 1 (VDAC1), two key regulators of glucose metabolisms as well as metabolic stress-induced apoptosis, were negatively correlated. In particular, VDAC1 was dramatically upregulated in cells that are sensitive to myostatin treatment whereas HKII was downregulated and dissociated from mitochondria. Myostatin promoted the translocation of Bax from cytosol to mitochondria, and knockdown of VDAC1 inhibited myostatin-induced Bax translocation and apoptosis. These apoptotic changes can be partially rescued by repletion of ATP, or by ectopic expression of HKII, suggesting that perturbation of mitochondrial metabolism is causally linked with subsequent apoptosis. Our findings reveal novel function of myostatin in regulating mitochondrial metabolism and apoptosis in cancer cells. PMID:23412387

HIV-1 transgenic rats display mitochondrial abnormalities consistent with abnormal energy generation and distribution.

PubMed

Villeneuve, Lance M; Purnell, Phillip R; Stauch, Kelly L; Callen, Shannon E; Buch, Shilpa J; Fox, Howard S

2016-10-01

With the advent of the combination antiretroviral therapy era (cART), the development of AIDS has been largely limited in the USA. Unfortunately, despite the development of efficacious treatments, HIV-1-associated neurocognitive disorders (HAND) can still develop, and as many HIV-1 positive individuals age, the prevalence of HAND is likely to rise because HAND manifests in the brain with very low levels of virus. However, the mechanism producing this viral disorder is still debated. Interestingly, HIV-1 infection exposes neurons to proteins including Tat, Nef, and Vpr which can drastically alter mitochondrial properties. Mitochondrial dysfunction has been posited to be a cornerstone of the development of numerous neurodegenerative diseases. Therefore, we investigated mitochondria in an animal model of HAND. Using an HIV-1 transgenic rat model expressing seven of the nine HIV-1 viral proteins, mitochondrial functional and proteomic analysis were performed on a subset of mitochondria that are particularly sensitive to cellular changes, the neuronal synaptic mitochondria. Quantitative mass spectroscopic studies followed by statistical analysis revealed extensive proteome alteration in this model paralleling mitochondrial abnormalities identified in HIV-1 animal models and HIV-1-infected humans. Novel mitochondrial protein changes were discovered in the electron transport chain (ETC), the glycolytic pathways, mitochondrial trafficking proteins, and proteins involved in various energy pathways, and these findings correlated well with the function of the mitochondria as assessed by a mitochondrial coupling and flux assay. By targeting these proteins and proteins upstream in the same pathway, we may be able to limit the development of HAND.

Ebselen alters mitochondrial physiology and reduces viability of rat hippocampal astrocytes.

PubMed

Santofimia-Castaño, Patricia; Salido, Ginés M; González, Antonio

2013-04-01

The seleno-organic compound and radical scavenger ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) have been extensively employed as an anti-inflammatory and neuroprotective compound. However, its glutathione peroxidase activity at the expense of cellular thiols groups could underlie certain deleterious actions of the compound on cell physiology. In this study, we have analyzed the effect of ebselen on rat hippocampal astrocytes in culture. Cellular viability, the intracellular free-Ca(2+) concentration ([Ca(2+)]c), the mitochondrial free-Ca(2+) concentration ([Ca(2+)]m), and mitochondrial membrane potential (ψm) were analyzed. The caspase-3 activity was also assayed. Our results show that cell viability was reduced by treatment of cells with ebselen, depending on the concentration employed. In the presence of ebselen, we observed an initial transient increase in [Ca(2+)]c that was then followed by a progressive increase to an elevated plateau. We also observed a transient increase in [Ca(2+)]m in the presence of ebselen that returned toward a value over the prestimulation level. The compound induced depolarization of ψm and altered the permeability of the mitochondrial membrane. Additionally, a disruption of the mitochondrial network was observed. Finally, we did not detect changes in caspase-3 activation in response to ebselen treatment. Collectively, these data support the likelihood of ebselen, depending on the concentration employed, reduces viability of rat hippocampal astrocytes via its action on the mitochondrial activity. These may be early effects that do not involve caspase-3 activation. We conclude that, depending on the concentration used, ebselen might exert deleterious actions on astrocyte physiology that could compromise cell function.

Betaine Treatment Attenuates Chronic Ethanol-Induced Hepatic Steatosis and Alterations to the Mitochondrial Respiratory Chain Proteome

PubMed Central

Kharbanda, Kusum K.; Todero, Sandra L.; King, Adrienne L.; Osna, Natalia A.; McVicker, Benita L.; Tuma, Dean J.; Wisecarver, James L.; Bailey, Shannon M.

2012-01-01

Introduction. Mitochondrial damage and disruption in oxidative phosphorylation contributes to the pathogenesis of alcoholic liver injury. Herein, we tested the hypothesis that the hepatoprotective actions of betaine against alcoholic liver injury occur at the level of the mitochondrial proteome. Methods. Male Wister rats were pair-fed control or ethanol-containing liquid diets supplemented with or without betaine (10 mg/mL) for 4-5 wks. Liver was examined for triglyceride accumulation, levels of methionine cycle metabolites, and alterations in mitochondrial proteins. Results. Chronic ethanol ingestion resulted in triglyceride accumulation which was attenuated in the ethanol plus betaine group. Blue native gel electrophoresis (BN-PAGE) revealed significant decreases in the content of the intact oxidative phosphorylation complexes in mitochondria from ethanol-fed animals. The alcohol-dependent loss in many of the low molecular weight oxidative phosphorylation proteins was prevented by betaine supplementation. This protection by betaine was associated with normalization of SAM : S-adenosylhomocysteine (SAH) ratios and the attenuation of the ethanol-induced increase in inducible nitric oxide synthase and nitric oxide generation in the liver. Discussion/Conclusion. In summary, betaine attenuates alcoholic steatosis and alterations to the oxidative phosphorylation system. Therefore, preservation of mitochondrial function may be another key molecular mechanism responsible for betaine hepatoprotection. PMID:22187660

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.

Mitochondrial dynamics in Parkinson's disease

PubMed Central

Van Laar, Victor S.; Berman, Sarah B.

2009-01-01

The unique energy demands of neurons require well-orchestrated distribution and maintenance of mitochondria. Thus, dynamic properties of mitochondria, including fission, fusion, trafficking, biogenesis, and degradation, are critical to all cells, but may be particularly important in neurons. Dysfunction in mitochondrial dynamics has been linked to neuropathies and is increasingly being linked to several neurodegenerative diseases, but the evidence is particularly strong, and continuously accumulating, in Parkinson's disease (PD). The unique characteristics of neurons that degenerate in PD may predispose those neuronal populations to susceptibility to alterations in mitochondrial dynamics. In addition, evidence from PD-related toxins supports that mitochondrial fission, fusion, and transport may be involved in pathogenesis. Furthermore, rapidly increasing evidence suggests that two proteins linked to familial forms of the disease, parkin and PINK1, interact in a common pathway to regulate mitochondrial fission/fusion. Parkin may also play a role in maintaining mitochondrial homeostasis through targeting damaged mitochondria for mitophagy. Taken together, the current data suggests that mitochondrial dynamics may play a role in PD pathogenesis, and a better understanding of mitochondrial dynamics within the neuron may lead to future therapeutic treatments for PD, potentially aimed at some of the earliest pathogenic events. PMID:19332061

Ectromelia Virus Affects Mitochondrial Network Morphology, Distribution, and Physiology in Murine Fibroblasts and Macrophage Cell Line

PubMed Central

Gregorczyk, Karolina P.; Wyżewski, Zbigniew; Szczepanowska, Joanna; Mielcarska, Matylda B.; Bossowska-Nowicka, Magdalena; Gieryńska, Małgorzata; Boratyńska-Jasińska, Anna; Niemiałtowski, Marek G.

2018-01-01

Mitochondria are multifunctional organelles that participate in numerous processes in response to viral infection, but they are also a target for viruses. The aim of this study was to define subcellular events leading to alterations in mitochondrial morphology and function during infection with ectromelia virus (ECTV). We used two different cell lines and a combination of immunofluorescence techniques, confocal and electron microscopy, and flow cytometry to address subcellular changes following infection. Early in infection of L929 fibroblasts and RAW 264.7 macrophages, mitochondria gathered around viral factories. Later, the mitochondrial network became fragmented, forming punctate mitochondria that co-localized with the progeny virions. ECTV-co-localized mitochondria associated with the cytoskeleton components. Mitochondrial membrane potential, mitochondrial fission–fusion, mitochondrial mass, and generation of reactive oxygen species (ROS) were severely altered later in ECTV infection leading to damage of mitochondria. These results suggest an important role of mitochondria in supplying energy for virus replication and morphogenesis. Presumably, mitochondria participate in transport of viral particles inside and outside of the cell and/or they are a source of membranes for viral envelope formation. We speculate that the observed changes in the mitochondrial network organization and physiology in ECTV-infected cells provide suitable conditions for viral replication and morphogenesis. PMID:29772718

Ectromelia Virus Affects Mitochondrial Network Morphology, Distribution, and Physiology in Murine Fibroblasts and Macrophage Cell Line.

PubMed

Gregorczyk, Karolina P; Wyżewski, Zbigniew; Szczepanowska, Joanna; Toka, Felix N; Mielcarska, Matylda B; Bossowska-Nowicka, Magdalena; Gieryńska, Małgorzata; Boratyńska-Jasińska, Anna; Struzik, Justyna; Niemiałtowski, Marek G; Szulc-Dąbrowska, Lidia

2018-05-16

Mitochondria are multifunctional organelles that participate in numerous processes in response to viral infection, but they are also a target for viruses. The aim of this study was to define subcellular events leading to alterations in mitochondrial morphology and function during infection with ectromelia virus (ECTV). We used two different cell lines and a combination of immunofluorescence techniques, confocal and electron microscopy, and flow cytometry to address subcellular changes following infection. Early in infection of L929 fibroblasts and RAW 264.7 macrophages, mitochondria gathered around viral factories. Later, the mitochondrial network became fragmented, forming punctate mitochondria that co-localized with the progeny virions. ECTV-co-localized mitochondria associated with the cytoskeleton components. Mitochondrial membrane potential, mitochondrial fission⁻fusion, mitochondrial mass, and generation of reactive oxygen species (ROS) were severely altered later in ECTV infection leading to damage of mitochondria. These results suggest an important role of mitochondria in supplying energy for virus replication and morphogenesis. Presumably, mitochondria participate in transport of viral particles inside and outside of the cell and/or they are a source of membranes for viral envelope formation. We speculate that the observed changes in the mitochondrial network organization and physiology in ECTV-infected cells provide suitable conditions for viral replication and morphogenesis.

Mitochondrial distribution and activity in human mature oocytes: gonadotropin-releasing hormone agonist versus antagonist for pituitary down-regulation.

PubMed

Dell'Aquila, Maria Elena; Ambruosi, Barbara; De Santis, Teresa; Cho, Yoon Sung

2009-01-01

To analyze the effects of GnRH agonists versus antagonists on mitochondrial distribution and activity in human mature oocytes. Randomized research experimental study. Academic basic research laboratory and hospital-based fertility center. Two hundred twenty-five supernumerary mature oocytes from 44 patients. Fluorescent staining and confocal laser scanning microscopy on oocytes after the use of either GnRH agonist (group A) or GnRH antagonist (group B). Oocyte mitochondrial distribution pattern and activity using MitoTracker Orange CMTM Ros. More oocytes showing polarized mitochondrial distribution pattern were found in group A than in group B (35% vs. 14%). In group B, hCG rather than GnRH agonist, for ovulation induction, resulted in more oocytes showing heterogeneous (57% vs. 14%), in particular polarized (24% vs. 0) mitochondrial distribution. In groups A and B, fluorescence intensity did not vary according to mitochondrial distribution pattern. However, fluorescence intensity was higher in oocytes with polarized and large granules configurations in group B compared to group A. The GnRH agonist and antagonist may have different effects on oocyte mitochondrial distribution pattern and activity. The GnRH antagonist may induce mitochondrial hyperactivity, which may be detrimental to the oocyte.

Lost region in amyloid precursor protein (APP) through TALEN-mediated genome editing alters mitochondrial morphology.

PubMed

Wang, Yajie; Wu, Fengyi; Pan, Haining; Zheng, Wenzhong; Feng, Chi; Wang, Yunfu; Deng, Zixin; Wang, Lianrong; Luo, Jie; Chen, Shi

2016-02-29

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) deposition in the brain. Aβ plaques are produced through sequential β/γ cleavage of amyloid precursor protein (APP), of which there are three main APP isoforms: APP695, APP751 and APP770. KPI-APPs (APP751 and APP770) are known to be elevated in AD, but the reason remains unclear. Transcription activator-like (TAL) effector nucleases (TALENs) induce mutations with high efficiency at specific genomic loci, and it is thus possible to knock out specific regions using TALENs. In this study, we designed and expressed TALENs specific for the C-terminus of APP in HeLa cells, in which KPI-APPs are predominantly expressed. The KPI-APP mutants lack a 12-aa region that encompasses a 5-aa trans-membrane (TM) region and 7-aa juxta-membrane (JM) region. The mutated KPI-APPs exhibited decreased mitochondrial localization. In addition, mitochondrial morphology was altered, resulting in an increase in spherical mitochondria in the mutant cells through the disruption of the balance between fission and fusion. Mitochondrial dysfunction, including decreased ATP levels, disrupted mitochondrial membrane potential, increased ROS generation and impaired mitochondrial dehydrogenase activity, was also found. These results suggest that specific regions of KPI-APPs are important for mitochondrial localization and function.

Maternal High Fat Diet Alters Skeletal Muscle Mitochondrial Catalytic Activity in Adult Male Rat Offspring

PubMed Central

Pileggi, Chantal A.; Hedges, Christopher P.; Segovia, Stephanie A.; Markworth, James F.; Durainayagam, Brenan R.; Gray, Clint; Zhang, Xiaoyuan D.; Barnett, Matthew P. G.; Vickers, Mark H.; Hickey, Anthony J. R.; Reynolds, Clare M.; Cameron-Smith, David

2016-01-01

A maternal high-fat (HF) diet during pregnancy can lead to metabolic compromise, such as insulin resistance in adult offspring. Skeletal muscle mitochondrial dysfunction is one mechanism contributing to metabolic impairments in insulin resistant states. Therefore, the present study aimed to investigate whether mitochondrial dysfunction is evident in metabolically compromised offspring born to HF-fed dams. Sprague-Dawley dams were randomly assigned to receive a purified control diet (CD; 10% kcal from fat) or a high fat diet (HFD; 45% kcal from fat) for 10 days prior to mating, throughout pregnancy and during lactation. From weaning, all male offspring received a standard chow diet and soleus muscle was collected at day 150. Expression of the mitochondrial transcription factors nuclear respiratory factor-1 (NRF1) and mitochondrial transcription factor A (mtTFA) were downregulated in HF offspring. Furthermore, genes encoding the mitochondrial electron transport system (ETS) respiratory complex subunits were suppressed in HF offspring. Moreover, protein expression of the complex I subunit, NDUFB8, was downregulated in HF offspring (36%), which was paralleled by decreased maximal catalytic linked activity of complex I and III (40%). Together, these results indicate that exposure to a maternal HF diet during development may elicit lifelong mitochondrial alterations in offspring skeletal muscle. PMID:27917127

Mitochondrial fatty acid oxidation alterations in heart failure, ischaemic heart disease and diabetic cardiomyopathy

PubMed Central

Fillmore, N; Mori, J; Lopaschuk, G D

2014-01-01

Heart disease is a leading cause of death worldwide. In many forms of heart disease, including heart failure, ischaemic heart disease and diabetic cardiomyopathies, changes in cardiac mitochondrial energy metabolism contribute to contractile dysfunction and to a decrease in cardiac efficiency. Specific metabolic changes include a relative increase in cardiac fatty acid oxidation rates and an uncoupling of glycolysis from glucose oxidation. In heart failure, overall mitochondrial oxidative metabolism can be impaired while, in ischaemic heart disease, energy production is impaired due to a limitation of oxygen supply. In both of these conditions, residual mitochondrial fatty acid oxidation dominates over mitochondrial glucose oxidation. In diabetes, the ratio of cardiac fatty acid oxidation to glucose oxidation also increases, although primarily due to an increase in fatty acid oxidation and an inhibition of glucose oxidation. Recent evidence suggests that therapeutically regulating cardiac energy metabolism by reducing fatty acid oxidation and/or increasing glucose oxidation can improve cardiac function of the ischaemic heart, the failing heart and in diabetic cardiomyopathies. In this article, we review the cardiac mitochondrial energy metabolic changes that occur in these forms of heart disease, what role alterations in mitochondrial fatty acid oxidation have in contributing to cardiac dysfunction and the potential for targeting fatty acid oxidation to treat these forms of heart disease. LINKED ARTICLES This article is part of a themed issue on Mitochondrial Pharmacology: Energy, Injury & Beyond. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2014.171.issue-8 PMID:24147975

Genetic ablation of calcium-independent phospholipase A2gamma leads to alterations in mitochondrial lipid metabolism and function resulting in a deficient mitochondrial bioenergetic phenotype.

PubMed

Mancuso, David J; Sims, Harold F; Han, Xianlin; Jenkins, Christopher M; Guan, Shao Ping; Yang, Kui; Moon, Sung Ho; Pietka, Terri; Abumrad, Nada A; Schlesinger, Paul H; Gross, Richard W

2007-11-30

Previously, we identified a novel calcium-independent phospholipase, designated calcium-independent phospholipase A(2) gamma (iPLA(2)gamma), which possesses dual mitochondrial and peroxisomal subcellular localization signals. To identify the roles of iPLA(2)gamma in cellular bioenergetics, we generated mice null for the iPLA(2)gamma gene by eliminating the active site of the enzyme through homologous recombination. Mice null for iPLA(2)gamma display multiple bioenergetic dysfunctional phenotypes, including 1) growth retardation, 2) cold intolerance, 3) reduced exercise endurance, 4) greatly increased mortality from cardiac stress after transverse aortic constriction, 5) abnormal mitochondrial function with a 65% decrease in ascorbate-induced Complex IV-mediated oxygen consumption, and 6) a reduction in myocardial cardiolipin content accompanied by an altered cardiolipin molecular species composition. We conclude that iPLA(2)gamma is essential for maintaining efficient bioenergetic mitochondrial function through tailoring mitochondrial membrane lipid metabolism and composition.

Mitochondrial Dynamics in Diabetic Cardiomyopathy

PubMed Central

Galloway, Chad A.

2015-01-01

Abstract Significance: Cardiac function is energetically demanding, reliant on efficient well-coupled mitochondria to generate adenosine triphosphate and fulfill the cardiac demand. Predictably then, mitochondrial dysfunction is associated with cardiac pathologies, often related to metabolic disease, most commonly diabetes. Diabetic cardiomyopathy (DCM), characterized by decreased left ventricular function, arises independently of coronary artery disease and atherosclerosis. Dysregulation of Ca2+ handling, metabolic changes, and oxidative stress are observed in DCM, abnormalities reflected in alterations in mitochondrial energetics. Cardiac tissue from DCM patients also presents with altered mitochondrial morphology, suggesting a possible role of mitochondrial dynamics in its pathological progression. Recent Advances: Abnormal mitochondrial morphology is associated with pathologies across diverse tissues, suggesting that this highly regulated process is essential for proper cell maintenance and physiological homeostasis. Highly structured cardiac myofibers were hypothesized to limit alterations in mitochondrial morphology; however, recent work has identified morphological changes in cardiac tissue, specifically in DCM. Critical Issues: Mitochondrial dysfunction has been reported independently from observations of altered mitochondrial morphology in DCM. The temporal relationship and causative nature between functional and morphological changes of mitochondria in the establishment/progression of DCM is unclear. Future Directions: Altered mitochondrial energetics and morphology are not only causal for but also consequential to reactive oxygen species production, hence exacerbating oxidative damage through reciprocal amplification, which is integral to the progression of DCM. Therefore, targeting mitochondria for DCM will require better mechanistic characterization of morphological distortion and bioenergetic dysfunction. Antioxid. Redox Signal. 22, 1545–1562. PMID

Targeted Transgenic Overexpression of Mitochondrial Thymidine Kinase (TK2) Alters Mitochondrial DNA (mtDNA) and Mitochondrial Polypeptide Abundance

PubMed Central

Hosseini, Seyed H.; Kohler, James J.; Haase, Chad P.; Tioleco, Nina; Stuart, Tami; Keebaugh, Erin; Ludaway, Tomika; Russ, Rodney; Green, Elgin; Long, Robert; Wang, Liya; Eriksson, Staffan; Lewis, William

2007-01-01

Mitochondrial toxicity limits nucleoside reverse transcriptase inhibitors (NRTIs) for acquired immune deficiency syndrome. NRTI triphosphates, the active moieties, inhibit human immunodeficiency virus reverse transcriptase and eukaryotic mitochondrial DNA polymerase pol-γ. NRTI phosphorylation seems to correlate with mitochondrial toxicity, but experimental evidence is lacking. Transgenic mice (TGs) with cardiac overexpression of thymidine kinase isoforms (mitochondrial TK2 and cytoplasmic TK1) were used to study NRTI mitochondrial toxicity. Echocardiography and nuclear magnetic resonance imaging defined cardiac performance and structure. TK gene copy and enzyme activity, mitochondrial (mt) DNA and polypeptide abundance, succinate dehydrogenase and cytochrome oxidase histochemistry, and electron microscopy correlated with transgenesis, mitochondrial structure, and biogenesis. Antiretroviral combinations simulated therapy. Untreated hTK1 or TK2 TGs exhibited normal left ventricle mass. In TK2 TGs, cardiac TK2 gene copy doubled, activity increased 300-fold, and mtDNA abundance doubled. Abundance of the 17-kd subunit of complex I, succinate dehydrogenase histochemical activity, and cristae density increased. NRTIs increased left ventricle mass 20% in TK2 TGs. TK activity increased 3 logs in hTK1 TGs, but no cardiac phenotype resulted. NRTIs abrogated functional effects of transgenically increased TK2 activity but had no effect on TK2 mtDNA abundance. Thus, NRTI mitochondrial phosphorylation by TK2 is integral to clinical NRTI mitochondrial toxicity. PMID:17322372

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

Altered Mitochondrial Membrane Potential, Mass, and Morphology in the Mononuclear Cells of Humans with Type 2 Diabetes

PubMed Central

Widlansky, Michael E.; Wang, Jingli; Shenouda, Sherene M.; Hagen, Tory M.; Smith, Anthony R.; Kizhakekuttu, Tinoy J.; Kluge, Matthew A.; Weihrauch, Dorothee; Gutterman, David D.; Vita, Joseph A.

2010-01-01

Mitochondrial membrane hyperpolarization and morphological changes are important in inflammatory cell activation. Despite the pathophysiological relevance, no valid and reproducible method for measuring mitochondrial homeostasis in human inflammatory cells is currently available. This study's purpose was to define and validate reproducible methods for measuring relevant mitochondrial perturbations and to determine whether these methods could discern mitochondrial perturbations in type 2 diabetes mellitus (T2DM), a condition associated with altered mitochondrial homeostasis. We employed 5,5',6,6'-tetrachloro-1,1'3,3'-tetraethylbenzamidazol-carboncyanine (JC-1) to estimate mitochondrial membrane potential (ψm) and acridine orange 10-nonyl bromide (NAO) to assess mitochondrial mass in human mononuclear cells isolated from blood. Both assays were reproducible. We validated our findings by electron microscopy and pharmacological manipulation of ψm. We measured JC-1 and NAO fluorescence in the mononuclear cells of 27 T2DM patients and 32 controls. Mitochondria were more polarized (P=0.02) and mitochondrial mass was lower in T2DM (P=0.008). Electron microscopy demonstrated diabetic mitochondria were smaller, more spherical, and occupied less cellular area in T2DM. Mitochondrial superoxide production was higher in T2DM (P=0.01). Valid and reproducible measurements of mitochondrial homeostasis can be made in human mononuclear cells using these fluorophores. Further, potential clinically relevant perturbations in mitochondrial homeostasis in T2DM human mononuclear cells can be detected. PMID:20621033

Prevalence of somatic mitochondrial mutations and spatial distribution of mitochondria in non-small cell lung cancer.

PubMed

Kazdal, Daniel; Harms, Alexander; Endris, Volker; Penzel, Roland; Kriegsmann, Mark; Eichhorn, Florian; Muley, Thomas; Stenzinger, Albrecht; Pfarr, Nicole; Weichert, Wilko; Warth, Arne

2017-07-11

Mitochondria are considered relevant players in many tumour entities and first data indicate beneficial effects of mitochondria-targeted antioxidants in both cancer prevention and anticancer therapies. To further dissect the potential roles of mitochondria in NSCLC we comprehensively analysed somatic mitochondrial mutations, determined the spatial distribution of mitochondrial DNA within complete tumour sections and investigated the mitochondrial load in a large-scale approach. Whole mitochondrial genome sequencing of 26 matched tumour and non-neoplastic tissue samples extended by reviewing published data of 326 cases. Systematical stepwise real-time PCR quantification of mitochondrial DNA covering 16 whole surgical tumour sections. Immunohistochemical determination of the mitochondrial load in 171 adenocarcinoma and 145 squamous cell carcinoma. Our results demonstrate very low recurrences (max. 1.7%) and a broad distribution of 456 different somatic mitochondrial mutations. Large inter- and intra-tumour heterogeneity were seen for mitochondrial DNA copy numbers in conjunction with a correlation to the predominant histological growth pattern. Furthermore, tumour cells had significantly higher mitochondrial level compared to adjacent stroma, whereas differences between tumour entities were negligible. Non-evident somatic mitochondrial mutations and highly varying mitochondrial DNA level delineate challenges for the approach of mitochondria-targeted anticancer therapies in NSCLC.

Alterations in mitochondrial respiratory functions, redox metabolism and apoptosis by oxidant 4-hydroxynonenal and antioxidants curcumin and melatonin in PC12 cells

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

Raza, Haider; John, Annie; Brown, Eric M.

Cellular oxidative stress and alterations in redox metabolisms have been implicated in the etiology and pathology of many diseases including cancer. Antioxidant treatments have been proven beneficial in controlling these diseases. We have recently shown that 4-hydroxynonenal (4-HNE), a by-product of lipid peroxidation, induces oxidative stress in PC12 cells by compromising the mitochondrial redox metabolism. In this study, we have further investigated the deleterious effects of 4-HNE on mitochondrial respiratory functions and apoptosis using the same cell line. In addition, we have also compared the effects of two antioxidants, curcumin and melatonin, used as chemopreventive agents, on mitochondrial redox metabolismmore » and respiratory functions in these cells. 4-HNE treatment has been shown to cause a reduction in glutathione (GSH) pool, an increase in reactive oxygen species (ROS), protein carbonylation and apoptosis. A marked inhibition in the activities of the mitochondrial respiratory enzymes, cytochrome c oxidase and aconitase was observed after 4-HNE treatment. Increased nuclear translocation of NF-kB/p65 protein was also observed after 4-HNE treatment. Curcumin and melatonin treatments, on the other hand, maintained the mitochondrial redox and respiratory functions without a marked effect on ROS production and cell viability. These results suggest that 4-HNE-induced cytotoxicity may be associated, at least in part, with the altered mitochondrial redox and respiratory functions. The alterations in mitochondrial energy metabolism and redox functions may therefore be critical in determining the difference between cell death and survival.« less

Mitochondrial NUDIX hydrolases: A metabolic link between NAD catabolism, GTP and mitochondrial dynamics.

PubMed

Long, Aaron; Klimova, Nina; Kristian, Tibor

2017-10-01

NAD + catabolism and mitochondrial dynamics are important parts of normal mitochondrial function and are both reported to be disrupted in aging, neurodegenerative diseases, and acute brain injury. While both processes have been extensively studied there has been little reported on how the mechanisms of these two processes are linked. This review focuses on how downstream NAD + catabolism via NUDIX hydrolases affects mitochondrial dynamics under pathologic conditions. Additionally, several potential targets in mitochondrial dysfunction and fragmentation are discussed, including the roles of mitochondrial poly(ADP-ribose) polymerase 1(mtPARP1), AMPK, AMP, and intra-mitochondrial GTP metabolism. Mitochondrial and cytosolic NUDIX hydrolases (NUDT9α and NUDT9β) can affect mitochondrial and cellular AMP levels by hydrolyzing ADP- ribose (ADPr) and subsequently altering the levels of GTP and ATP. Poly (ADP-ribose) polymerase 1 (PARP1) is activated after DNA damage, which depletes NAD + pools and results in the PARylation of nuclear and mitochondrial proteins. In the mitochondria, ADP-ribosyl hydrolase-3 (ARH3) hydrolyzes PAR to ADPr, while NUDT9α metabolizes ADPr to AMP. Elevated AMP levels have been reported to reduce mitochondrial ATP production by inhibiting the adenine nucleotide translocase (ANT), allosterically activating AMPK by altering the cellular AMP: ATP ratio, and by depleting mitochondrial GTP pools by being phosphorylated by adenylate kinase 3 (AK3), which uses GTP as a phosphate donor. Recently, activated AMPK was reported to phosphorylate mitochondria fission factor (MFF), which increases Drp1 localization to the mitochondria and promotes mitochondrial fission. Moreover, the increased AK3 activity could deplete mitochondrial GTP pools and possibly inhibit normal activity of GTP-dependent fusion enzymes, thus altering mitochondrial dynamics. Published by Elsevier Ltd.

Wide Distribution of Mitochondrial Genome Rearrangements in Wild Strains of the Cultivated Basidiomycete Agrocybe aegerita

PubMed Central

Barroso, G.; Blesa, S.; Labarere, J.

1995-01-01

We used restriction fragment length polymorphisms to examine mitochondrial genome rearrangements in 36 wild strains of the cultivated basidiomycete Agrocybe aegerita, collected from widely distributed locations in Europe. We identified two polymorphic regions within the mitochondrial DNA which varied independently: one carrying the Cox II coding sequence and the other carrying the Cox I, ATP6, and ATP8 coding sequences. Two types of mutations were responsible for the restriction fragment length polymorphisms that we observed and, accordingly, were involved in the A. aegerita mitochondrial genome evolution: (i) point mutations, which resulted in strain-specific mitochondrial markers, and (ii) length mutations due to genome rearrangements, such as deletions, insertions, or duplications. Within each polymorphic region, the length differences defined only two mitochondrial types, suggesting that these length mutations were not randomly generated but resulted from a precise rearrangement mechanism. For each of the two polymorphic regions, the two molecular types were distributed among the 36 strains without obvious correlation with their geographic origin. On the basis of these two polymorphisms, it is possible to define four mitochondrial haplotypes. The four mitochondrial haplotypes could be the result of intermolecular recombination between allelic forms present in the population long enough to reach linkage equilibrium. All of the 36 dikaryotic strains contained only a single mitochondrial type, confirming the previously described mitochondrial sorting out after cytoplasmic mixing in basidiomycetes. PMID:16534984

Hypoxia/oxidative stress alters the pharmacokinetics of CPU86017-RS through mitochondrial dysfunction and NADPH oxidase activation.

PubMed

Gao, Jie; Ding, Xuan-sheng; Zhang, Yu-mao; Dai, De-zai; Liu, Mei; Zhang, Can; Dai, Yin

2013-12-01

Hypoxia/oxidative stress can alter the pharmacokinetics (PK) of CPU86017-RS, a novel antiarrhythmic agent. The aim of this study was to investigate the mechanisms underlying the alteration of PK of CPU86017-RS by hypoxia/oxidative stress. Male SD rats exposed to normal or intermittent hypoxia (10% O2) were administered CPU86017-RS (20, 40 or 80 mg/kg, ig) for 8 consecutive days. The PK parameters of CPU86017-RS were examined on d 8. In a separate set of experiments, female SD rats were injected with isoproterenol (ISO) for 5 consecutive days to induce a stress-related status, then CPU86017-RS (80 mg/kg, ig) was administered, and the tissue distributions were examined. The levels of Mn-SOD (manganese containing superoxide dismutase), endoplasmic reticulum (ER) stress sensor proteins (ATF-6, activating transcription factor 6 and PERK, PRK-like ER kinase) and activation of NADPH oxidase (NOX) were detected with Western blotting. Rat liver microsomes were incubated under N2 for in vitro study. The Cmax, t1/2, MRT (mean residence time) and AUC (area under the curve) of CPU86017-RS were significantly increased in the hypoxic rats receiving the 3 different doses of CPU86017-RS. The hypoxia-induced alteration of PK was associated with significantly reduced Mn-SOD level, and increased ATF-6, PERK and NOX levels. In ISO-treated rats, the distributions of CPU86017-RS in plasma, heart, kidney, and liver were markedly increased, and NOX levels in heart, kidney, and liver were significantly upregulated. Co-administration of the NOX blocker apocynin eliminated the abnormalities in the PK and tissue distributions of CPU86017-RS induced by hypoxia/oxidative stress. The metabolism of CPU86017-RS in the N2-treated liver microsomes was significantly reduced, addition of N-acetylcysteine (NAC), but not vitamin C, effectively reversed this change. The altered PK and metabolism of CPU86017-RS induced by hypoxia/oxidative stress are produced by mitochondrial abnormalities, NOX activation

Quadriceps exercise intolerance in patients with chronic obstructive pulmonary disease: the potential role of altered skeletal muscle mitochondrial respiration.

PubMed

Gifford, Jayson R; Trinity, Joel D; Layec, Gwenael; Garten, Ryan S; Park, Song-Young; Rossman, Matthew J; Larsen, Steen; Dela, Flemming; Richardson, Russell S

2015-10-15

This study sought to determine if qualitative alterations in skeletal muscle mitochondrial respiration, associated with decreased mitochondrial efficiency, contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). Using permeabilized muscle fibers from the vastus lateralis of 13 patients with COPD and 12 healthy controls, complex I (CI) and complex II (CII)-driven State 3 mitochondrial respiration were measured separately (State 3:CI and State 3:CII) and in combination (State 3:CI+CII). State 2 respiration was also measured. Exercise tolerance was assessed by knee extensor exercise (KE) time to fatigue. Per milligram of muscle, State 3:CI+CII and State 3:CI were reduced in COPD (P < 0.05), while State 3:CII and State 2 were not different between groups. To determine if this altered pattern of respiration represented qualitative changes in mitochondrial function, respiration states were examined as percentages of peak respiration (State 3:CI+CII), which revealed altered contributions from State 3:CI (Con 83.7 ± 3.4, COPD 72.1 ± 2.4%Peak, P < 0.05) and State 3:CII (Con 64.9 ± 3.2, COPD 79.5 ± 3.0%Peak, P < 0.05) respiration, but not State 2 respiration in COPD. Importantly, a diminished contribution of CI-driven respiration relative to the metabolically less-efficient CII-driven respiration (CI/CII) was also observed in COPD (Con 1.28 ± 0.09, COPD 0.81 ± 0.05, P < 0.05), which was related to exercise tolerance of the patients (r = 0.64, P < 0.05). Overall, this study indicates that COPD is associated with qualitative alterations in skeletal muscle mitochondria that affect the contribution of CI and CII-driven respiration, which potentially contributes to the exercise intolerance associated with this 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.

Selenium suppresses glutamate-induced cell death and prevents mitochondrial morphological dynamic alterations in hippocampal HT22 neuronal cells.

PubMed

Ma, Yan-Mei; Ibeanu, Gordon; Wang, Li-Yao; Zhang, Jian-Zhong; Chang, Yue; Dong, Jian-Da; Li, P Andy; Jing, Li

2017-01-19

Previous studies have indicated that selenium supplementation may be beneficial in neuroprotection against glutamate-induced cell damage, in which mitochondrial dysfunction is considered a major pathogenic feature. However, the exact mechanisms by which selenium protects against glutamate-provoked mitochondrial perturbation remain ambiguous. In this study glutamate exposed murine hippocampal neuronal HT22 cell was used as a model to investigate the underlying mechanisms of selenium-dependent protection against mitochondria damage. We find that glutamate-induced cytotoxicity was associated with enhancement of superoxide production, activation of caspase-9 and -3, increases of mitochondrial fission marker and mitochondrial morphological changes. Selenium significantly resolved the glutamate-induced mitochondria structural damage, alleviated oxidative stress, decreased Apaf-1, caspases-9 and -3 contents, and altered the autophagy process as observed by a decline in the ratio of the autophagy markers LC3-I and LC3-II. These findings suggest that the protection of selenium against glutamate stimulated cell damage of HT22 cells is associated with amelioration of mitochondrial dynamic imbalance.

No difference in mitochondrial distribution is observed in human oocytes after cryopreservation.

PubMed

Stimpfel, Martin; Vrtacnik-Bokal, Eda; Virant-Klun, Irma

2017-08-01

The primary aim of this study was to determine if any difference in mitochondrial distribution can be observed between fresh and cryopreserved (slow-frozen/thawed and vitrified/warmed) oocytes when oocytes are stained with Mitotracker Red CMXRos and observed under a conventional fluorescent microscope. Additionally, the influence of cryopreservation procedure on the viable rates of oocytes at different maturation stages was evaluated. The germinal vesicle (GV) and MII oocytes were cryopreserved with slow-freezing and vitrification. After thawing/warming, oocytes were stained using Mitotracker Red CMXRos and observed under a conventional fluorescent microscope. Mitotracker staining revealed that in GV oocytes the pattern of mitochondrial distribution appeared as aggregated clusters around the whole oocyte. In mature MII oocytes, three different patterns of mitochondrial distribution were observed; a smooth pattern around the polar body with aggregated clusters at the opposite side of the polar body, a smooth pattern throughout the whole cell, and aggregated clusters as can be seen in GV oocytes. There were no significant differences in the observed patterns between fresh, vitrified/warmed and frozen/thawed oocytes. When comparing the viable rates of oocytes after two different cryopreservation procedures, the results showed no significant differences, although the trend of viable MII oocytes tends to be higher after vitrification/warming and for viable GV oocytes it tends to be higher after slow-freezing/thawing. Mitotracker Red CMXRos staining of mitochondria in oocytes did not reveal differences in mitochondrial distribution between fresh and cryopreserved oocytes at different maturity stages. Additionally, no difference was observed in the viable rates of GV and MII oocytes after slow-freezing/thawing and vitrification/warming.

Mitochondrial nucleoid interacting proteins support mitochondrial protein synthesis.

PubMed

He, J; Cooper, H M; Reyes, A; Di Re, M; Sembongi, H; Litwin, T R; Gao, J; Neuman, K C; Fearnley, I M; Spinazzola, A; Walker, J E; Holt, I J

2012-07-01

Mitochondrial ribosomes and translation factors co-purify with mitochondrial nucleoids of human cells, based on affinity protein purification of tagged mitochondrial DNA binding proteins. Among the most frequently identified proteins were ATAD3 and prohibitin, which have been identified previously as nucleoid components, using a variety of methods. Both proteins are demonstrated to be required for mitochondrial protein synthesis in human cultured cells, and the major binding partner of ATAD3 is the mitochondrial ribosome. Altered ATAD3 expression also perturbs mtDNA maintenance and replication. These findings suggest an intimate association between nucleoids and the machinery of protein synthesis in mitochondria. ATAD3 and prohibitin are tightly associated with the mitochondrial membranes and so we propose that they support nucleic acid complexes at the inner membrane of the mitochondrion.

Mitochondrial and Morphologic Alterations in Native Human Corneal Endothelial Cells Associated With Diabetes Mellitus.

PubMed

Aldrich, Benjamin T; Schlötzer-Schrehardt, Ursula; Skeie, Jessica M; Burckart, Kimberlee A; Schmidt, Gregory A; Reed, Cynthia R; Zimmerman, M Bridget; Kruse, Friedrich E; Greiner, Mark A

2017-04-01

To characterize changes in the energy-producing metabolic activity and morphologic ultrastructure of corneal endothelial cells associated with diabetes mellitus. Transplant suitable corneoscleral tissue was obtained from donors aged 50 to 75 years. We assayed 3-mm punches of endothelium-Descemet membrane for mitochondrial respiration and glycolysis activity using extracellular flux analysis of oxygen and pH, respectively. Transmission electron microscopy was used to assess qualitative and quantitative ultrastructural changes in corneal endothelial cells and associated Descemet membrane. For purposes of analysis, samples were divided into four groups based on a medical history of diabetes regardless of type: (1) nondiabetic, (2) noninsulin-dependent diabetic, (3) insulin-dependent diabetic, and (4) insulin-dependent diabetic with specified complications due to diabetes (advanced diabetic). In total, 229 corneas from 159 donors were analyzed. Insulin-dependent diabetic samples with complications due to diabetes displayed the lowest spare respiratory values compared to all other groups (P ≤ 0.002). The remaining mitochondrial respiration and glycolysis metrics did not differ significantly among groups. Compared to nondiabetic controls, the endothelium from advanced diabetic samples had alterations in mitochondrial morphology, pronounced Golgi bodies associated with abundant vesicles, accumulation of lysosomal bodies/autophagosomes, and focal production of abnormal long-spacing collagen. Extracellular flux analysis suggests that corneal endothelial cells of donors with advanced diabetes have impaired mitochondrial function. Metabolic findings are supported by observed differences in mitochondrial morphology of advanced diabetic samples but not controls. Additional studies are needed to determine the precise mechanism(s) by which mitochondria become impaired in diabetic corneal endothelial cells.

Oxidative stress generated during monensin treatment contributes to altered Toxoplasma gondii mitochondrial function

PubMed Central

Charvat, Robert A.; Arrizabalaga, Gustavo

2016-01-01

The ionophore monensin displays potent activities against several coccidian parasites of veterinary and medical importance including the opportunistic pathogen of humans, Toxoplasma gondii. While monensin is used widely in animals, toxicity impedes its use in humans. Nonetheless, given its potency, understanding its mode of action would reveal vulnerable aspects of the parasite that can be exploited for drug development. We previously established that monensin induces Toxoplasma to undergo cell cycle arrest and an autophagy-like cell death. Interestingly, these effects are dependent on the mitochondrion-localized TgMSH-1 protein, suggesting that monensin disrupts mitochondrial function. We demonstrate that monensin treatment results in decreased mitochondrial membrane potential and altered morphology. These effects are mitigated by the antioxidant compound N-acetyl-cysteine suggesting that monensin causes an oxidative stress, which was indeed the case based on direct detection of reactive oxygen species. Moreover, over-expression of the antioxidant proteins glutaredoxin and peroxiredoxin 2 protect Toxoplasma from the deleterious effects of monensin. Thus, our studies show that the effects of monensin on Toxoplasma are due to a disruption of mitochondrial function caused by the induction of an oxidative stress and implicate parasite redox biology as a viable target for the development of drugs against Toxoplasma and related pathogenic parasites. PMID:26976749

Aspirin increases mitochondrial fatty acid oxidation

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

Uppala, Radha; Dudiak, Brianne; Beck, Megan E.

The metabolic effects of salicylates are poorly understood. This study investigated the effects of aspirin on fatty acid oxidation. Aspirin increased mitochondrial long-chain fatty acid oxidation, but inhibited peroxisomal fatty acid oxidation, in two different cell lines. Aspirin increased mitochondrial protein acetylation and was found to be a stronger acetylating agent in vitro than acetyl-CoA. However, aspirin-induced acetylation did not alter the activity of fatty acid oxidation proteins, and knocking out the mitochondrial deacetylase SIRT3 did not affect the induction of long-chain fatty acid oxidation by aspirin. Aspirin did not change oxidation of medium-chain fatty acids, which can freely traverse themore » mitochondrial membrane. Together, these data indicate that aspirin does not directly alter mitochondrial matrix fatty acid oxidation enzymes, but most likely exerts its effects at the level of long-chain fatty acid transport into mitochondria. The drive on mitochondrial fatty acid oxidation may be a compensatory response to altered mitochondrial morphology and inhibited electron transport chain function, both of which were observed after 24 h incubation of cells with aspirin. These studies provide insight into the pathophysiology of Reye Syndrome, which is known to be triggered by aspirin ingestion in patients with fatty acid oxidation disorders. - Highlights: • Aspirin increases mitochondrial—but inhibits peroxisomal—fatty acid oxidation. • Aspirin acetylates mitochondrial proteins including fatty acid oxidation enzymes. • SIRT3 does not influence the effect of aspirin on fatty acid oxidation. • Increased fatty acid oxidation is likely due to altered mitochondrial morphology and respiration.« less

Deleterious variants in TRAK1 disrupt mitochondrial movement and cause fatal encephalopathy.

PubMed

Barel, Ortal; Malicdan, May Christine V; Ben-Zeev, Bruria; Kandel, Judith; Pri-Chen, Hadass; Stephen, Joshi; Castro, Inês G; Metz, Jeremy; Atawa, Osama; Moshkovitz, Sharon; Ganelin, Esther; Barshack, Iris; Polak-Charcon, Sylvie; Nass, Dvora; Marek-Yagel, Dina; Amariglio, Ninette; Shalva, Nechama; Vilboux, Thierry; Ferreira, Carlos; Pode-Shakked, Ben; Heimer, Gali; Hoffmann, Chen; Yardeni, Tal; Nissenkorn, Andreea; Avivi, Camila; Eyal, Eran; Kol, Nitzan; Glick Saar, Efrat; Wallace, Douglas C; Gahl, William A; Rechavi, Gideon; Schrader, Michael; Eckmann, David M; Anikster, Yair

2017-03-01

Cellular distribution and dynamics of mitochondria are regulated by several motor proteins and a microtubule network. In neurons, mitochondrial trafficking is crucial because of high energy needs and calcium ion buffering along axons to synapses during neurotransmission. The trafficking kinesin proteins (TRAKs) are well characterized for their role in lysosomal and mitochondrial trafficking in cells, especially neurons. Using whole exome sequencing, we identified homozygous truncating variants in TRAK1 (NM_001042646:c.287-2A > C), in six lethal encephalopathic patients from three unrelated families. The pathogenic variant results in aberrant splicing and significantly reduced gene expression at the RNA and protein levels. In comparison with normal cells, TRAK1-deficient fibroblasts showed irregular mitochondrial distribution, altered mitochondrial motility, reduced mitochondrial membrane potential, and diminished mitochondrial respiration. This study confirms the role of TRAK1 in mitochondrial dynamics and constitutes the first report of this gene in association with a severe neurodevelopmental disorder. © Published by Oxford University Press on behalf of the Guarantors of Brain 2017. This work is written by US Government employees and is in the public domain in the US.

Unraveling Biochemical Pathways Affected by Mitochondrial Dysfunctions Using Metabolomic Approaches

PubMed Central

Demine, Stéphane; Reddy, Nagabushana; Renard, Patricia; Raes, Martine; Arnould, Thierry

2014-01-01

Mitochondrial dysfunction(s) (MDs) can be defined as alterations in the mitochondria, including mitochondrial uncoupling, mitochondrial depolarization, inhibition of the mitochondrial respiratory chain, mitochondrial network fragmentation, mitochondrial or nuclear DNA mutations and the mitochondrial accumulation of protein aggregates. All these MDs are known to alter the capacity of ATP production and are observed in several pathological states/diseases, including cancer, obesity, muscle and neurological disorders. The induction of MDs can also alter the secretion of several metabolites, reactive oxygen species production and modify several cell-signalling pathways to resolve the mitochondrial dysfunction or ultimately trigger cell death. Many metabolites, such as fatty acids and derived compounds, could be secreted into the blood stream by cells suffering from mitochondrial alterations. In this review, we summarize how a mitochondrial uncoupling can modify metabolites, the signalling pathways and transcription factors involved in this process. We describe how to identify the causes or consequences of mitochondrial dysfunction using metabolomics (liquid and gas chromatography associated with mass spectrometry analysis, NMR spectroscopy) in the obesity and insulin resistance thematic. PMID:25257998

Alteration in mitochondrial function and glutamate metabolism affected by 2-chloroethanol in primary cultured astrocytes.

PubMed

Sun, Qi; Liao, Yingjun; Wang, Tong; Wang, Gaoyang; Zhao, Fenghong; Jin, Yaping

2016-12-01

The aim of this study was to explore the mechanisms that contribute to 1,2-dichloroethane (1,2-DCE) induced brain edema by focusing on alteration of mitochondrial function and glutamate metabolism in primary cultured astrocytes induced by 2-chloroethanol (2-CE), a metabolite of 1,2-DCE in vivo. The cells were exposed to different levels of 2-CE in the media for 24h. Mitochondrial function was evaluated by its membrane potential and intracellular contents of ATP, lactic acid and reactive oxygen species (ROS). Glutamate metabolism was indicated by expression of glutamine synthase (GS), glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) at both protein and gene levels. Compared to the control group, exposure to 2-CE could cause a dose dependent damage in astrocytes, indicated by decreased cell viability and morphological changes, and supported by decreased levels of nonprotein sulfhydryl (NPSH) and inhibited activities of Na + /K + -ATPase and Ca 2+ -ATPase in the cells. The present study also revealed both mitochondrial function and glutamate metabolism in astrocytes were significantly disturbed by 2-CE. Of which, mitochondrial function was much vulnerable to the effects of 2-CE. In conclusion, our findings suggested that mitochondrial dysfunction and glutamate metabolism disorder could contribute to 2-CE-induced cytotoxicity in astrocytes, which might be related to 1,2-DCE-induced brain edema. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Hypertension-Associated tRNAAla Mutation Alters tRNA Metabolism and Mitochondrial Function

PubMed Central

Jiang, Pingping; Wang, Meng; Xue, Ling; Xiao, Yun; Yu, Jialing; Wang, Hui; Yao, Juan; Liu, Hao; Peng, Yanyan; Liu, Hanqing; Li, Haiying; Chen, Ye

2016-01-01

In this report, we investigated the pathophysiology of a novel hypertension-associated mitochondrial tRNAAla 5655A → G (m.5655A → G) mutation. The destabilization of a highly conserved base pairing (A1-U72) at the aminoacyl acceptor stem by an m.5655A → G mutation altered the tRNAAla function. An in vitro processing analysis showed that the m.5655A → G mutation reduced the efficiency of tRNAAla precursor 5′ end cleavage catalyzed by RNase P. By using cybrids constructed by transferring mitochondria from lymphoblastoid cell lines derived from a Chinese family into mitochondrial DNA (mtDNA)-less (ρo) cells, we showed a 41% reduction in the steady-state level of tRNAAla in mutant cybrids. The mutation caused an improperly aminoacylated tRNAAla, as suggested by aberrantly aminoacylated tRNAAla and slower electrophoretic mobility of mutated tRNA. A failure in tRNAAla metabolism contributed to variable reductions in six mtDNA-encoded polypeptides in mutant cells, ranging from 21% to 37.5%, with an average of a 29.1% reduction, compared to levels of the controls. The impaired translation caused reduced activities of mitochondrial respiration chains. Furthermore, marked decreases in the levels of mitochondrial ATP and membrane potential were observed in mutant cells. These caused increases in the production of reactive oxygen species in the mutant cybrids. The data provide evidence for the association of the tRNAAla 5655A → G mutation with hypertension. PMID:27161322

Altered mitochondrial quality control signaling in muscle of old gastric cancer patients with cachexia.

PubMed

Marzetti, Emanuele; Lorenzi, Maria; Landi, Francesco; Picca, Anna; Rosa, Fausto; Tanganelli, Fabiana; Galli, Marco; Doglietto, Giovanni Battista; Pacelli, Fabio; Cesari, Matteo; Bernabei, Roberto; Calvani, Riccardo; Bossola, Maurizio

2017-01-01

Mitochondrial dysfunction is involved in the loss of muscle featuring both aging and cancer cachexia (CC). Whether mitochondrial quality control (MQC) is altered in skeletal myocytes of old patients with CC is unclear. The present investigation therefore sought to preliminarily characterize MQC pathways in muscle of old gastric cancer patients with cachexia. The study followed a case-control cross-sectional design. Intraoperative biopsies of the rectus abdominis muscle were obtained from 18 patients with gastric adenocarcinoma (nine with CC and nine non-cachectic) and nine controls, and assayed for the expression of a set of MQC mediators. The mitofusin 2 expression was reduced in cancer patients compared with controls, independent of CC. Fission protein 1 was instead up-regulated in CC patients relative to the other groups. The mitophagy regulators PTEN-induced putative kinase 1 and Parkin were both down-regulated in cancer patients compared with controls. The ratio between the protein content of the lipidated and non-lipidated forms of microtubule-associated protein 1 light chain 3B was lower in CC patients relative to controls and non-cachectic cancer patients. Finally, the expression of autophagy-associated protein 7, lysosome-associated membrane protein 2, peroxisome proliferator-activated receptor-γ coactivator-1α, and mitochondrial transcription factor A was unvarying among groups. Collectively, our findings indicate that, in old patients with gastric cancer, cachexia is associated with derangements of the muscular MQC axis at several checkpoints: mitochondrial dynamics, mitochondrial tagging for disposal, and mitophagy signaling. Further investigations are needed to corroborate these preliminary findings and determine whether MQC pathways may become target for future interventions. Copyright © 2016 Elsevier Inc. All rights reserved.

Altered mitochondrial bioenergetics and ultrastructure in the skeletal muscle of young adults with type 1 diabetes.

PubMed

Monaco, Cynthia M F; Hughes, Meghan C; Ramos, Sofhia V; Varah, Nina E; Lamberz, Christian; Rahman, Fasih A; McGlory, Chris; Tarnopolsky, Mark A; Krause, Matthew P; Laham, Robert; Hawke, Thomas J; Perry, Christopher G R

2018-06-01

A comprehensive assessment of skeletal muscle ultrastructure and mitochondrial bioenergetics has not been undertaken in individuals with type 1 diabetes. This study aimed to systematically assess skeletal muscle mitochondrial phenotype in young adults with type 1 diabetes. Physically active, young adults (men and women) with type 1 diabetes (HbA 1c 63.0 ± 16.0 mmol/mol [7.9% ± 1.5%]) and without type 1 diabetes (control), matched for sex, age, BMI and level of physical activity, were recruited (n = 12/group) to undergo vastus lateralis muscle microbiopsies. Mitochondrial respiration (high-resolution respirometry), site-specific mitochondrial H 2 O 2 emission and Ca 2+ retention capacity (CRC) (spectrofluorometry) were assessed using permeabilised myofibre bundles. Electron microscopy and tomography were used to quantify mitochondrial content and investigate muscle ultrastructure. Skeletal muscle microvasculature was assessed by immunofluorescence. Mitochondrial oxidative capacity was significantly lower in participants with type 1 diabetes vs the control group, specifically at Complex II of the electron transport chain, without differences in mitochondrial content between groups. Muscles of those with type 1 diabetes also exhibited increased mitochondrial H 2 O 2 emission at Complex III and decreased CRC relative to control individuals. Electron tomography revealed an increase in the size and number of autophagic remnants in the muscles of participants with type 1 diabetes. Despite this, levels of the autophagic regulatory protein, phosphorylated AMP-activated protein kinase (p-AMPKα Thr172 ), and its downstream targets, phosphorylated Unc-51 like autophagy activating kinase 1 (p-ULK1 Ser555 ) and p62, was similar between groups. In addition, no differences in muscle capillary density or platelet aggregation were observed between the groups. Alterations in mitochondrial ultrastructure and bioenergetics are evident within the skeletal muscle of

Discrete mitochondrial aberrations in the spinal cord of sporadic ALS patients.

PubMed

Delic, Vedad; Kurien, Crupa; Cruz, Josean; Zivkovic, Sandra; Barretta, Jennifer; Thomson, Avery; Hennessey, Daniel; Joseph, Jaheem; Ehrhart, Jared; Willing, Alison E; Bradshaw, Patrick; Garbuzova-Davis, Svitlana

2018-08-01

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease characterized by progressive motor neuron degeneration in the brain and spinal cord leading to muscle atrophy, paralysis, and death. Mitochondrial dysfunction is a major contributor to motor neuron degeneration associated with ALS progression. Mitochondrial abnormalities have been determined in spinal cords of animal disease models and ALS patients. However, molecular mechanisms leading to mitochondrial dysfunction in sporadic ALS (sALS) patients remain unclear. Also, segmental or regional variation in mitochondrial activity in the spinal cord has not been extensively examined in ALS. In our study, the activity of mitochondrial electron transport chain complex IV was examined in post-mortem gray and white matter of the cervical and lumbar spinal cords from male and female sALS patients and controls. Mitochondrial distribution and density in spinal cord motor neurons, lateral funiculus, and capillaries in gray and white matter were analyzed by immunohistochemistry. Results showed that complex IV activity was significantly decreased only in gray matter in both cervical and lumbar spinal cords from ALS patients. In ALS cervical and lumbar spinal cords, significantly increased mitochondrial density and altered distribution were observed in motor neurons, lateral funiculus, and cervical white matter capillaries. Discrete decreased complex IV activity in addition to changes in mitochondria distribution and density determined in the spinal cord in sALS patients are novel findings. These explicit mitochondrial defects in the spinal cord may contribute to ALS pathogenesis and should be considered in development of therapeutic approaches for this disease. © 2018 Wiley Periodicals, Inc.

Inflammation in adult women with a history of child maltreatment: The involvement of mitochondrial alterations and oxidative stress.

PubMed

Boeck, Christina; Koenig, Alexandra Maria; Schury, Katharina; Geiger, Martha Leonie; Karabatsiakis, Alexander; Wilker, Sarah; Waller, Christiane; Gündel, Harald; Fegert, Jörg Michael; Calzia, Enrico; Kolassa, Iris-Tatjana

2016-09-01

The experience of maltreatment during childhood is associated with chronic low-grade inflammation in adulthood. However, the molecular mechanisms underlying this pro-inflammatory phenotype remain unclear. Mitochondria were recently found to principally coordinate inflammatory processes via both inflammasome activation and inflammasome-independent pathways. To this end, we hypothesized that alterations in immune cell mitochondrial functioning and oxidative stress might be at the interface between the association of maltreatment experiences during childhood and inflammation. We analyzed pro-inflammatory biomarkers (levels of C-reactive protein, cytokine secretion by peripheral blood mononuclear cells (PBMC) in vitro, PBMC composition, lysophosphatidylcholine levels), serum oxidative stress levels (arginine:citrulline ratio, l-carnitine and acetylcarnitine levels) and mitochondrial functioning (respiratory activity and density of mitochondria in PBMC) in peripheral blood samples collected from 30 women (aged 22-44years) with varying degrees of maltreatment experiences in form of abuse and neglect during childhood. Exposure to maltreatment during childhood was associated with an increased ROS production, higher levels of oxidative stress and an increased mitochondrial activity in a dose-response relationship. Moreover, the increase in mitochondrial activity and ROS production were positively associated with the release of pro-inflammatory cytokines by PBMC. Decreased serum levels of lysophosphatidylcholines suggested higher inflammasome activation with increasing severity of child maltreatment experiences. Together these findings offer preliminary evidence for the association of alterations in immune cell mitochondrial functioning, oxidative stress and the pro-inflammatory phenotype observed in individuals with a history of maltreatment during childhood. The results emphasize that the early prevention of child abuse and neglect warrants more attention, as the

Mitochondrial dysfunction in obesity.

PubMed

de Mello, Aline Haas; Costa, Ana Beatriz; Engel, Jéssica Della Giustina; Rezin, Gislaine Tezza

2018-01-01

Obesity leads to various changes in the body. Among them, the existing inflammatory process may lead to an increase in the production of reactive oxygen species (ROS) and cause oxidative stress. Oxidative stress, in turn, can trigger mitochondrial changes, which is called mitochondrial dysfunction. Moreover, excess nutrients supply (as it commonly is the case with obesity) can overwhelm the Krebs cycle and the mitochondrial respiratory chain, causing a mitochondrial dysfunction, and lead to a higher ROS formation. This increase in ROS production by the respiratory chain may also cause oxidative stress, which may exacerbate the inflammatory process in obesity. All these intracellular changes can lead to cellular apoptosis. These processes have been described in obesity as occurring mainly in peripheral tissues. However, some studies have already shown that obesity is also associated with changes in the central nervous system (CNS), with alterations in the blood-brain barrier (BBB) and in cerebral structures such as hypothalamus and hippocampus. In this sense, this review presents a general view about mitochondrial dysfunction in obesity, including related alterations, such as inflammation, oxidative stress, and apoptosis, and focusing on the whole organism, covering alterations in peripheral tissues, BBB, and CNS. Copyright © 2017 Elsevier Inc. All rights reserved.

Telmisartan enhances mitochondrial activity and alters cellular functions in human coronary artery endothelial cells via AMP-activated protein kinase pathway.

PubMed

Kurokawa, Hirofumi; Sugiyama, Seigo; Nozaki, Toshimitsu; Sugamura, Koichi; Toyama, Kensuke; Matsubara, Junichi; Fujisue, Koichiro; Ohba, Keisuke; Maeda, Hirofumi; Konishi, Masaaki; Akiyama, Eiichi; Sumida, Hitoshi; Izumiya, Yasuhiro; Yasuda, Osamu; Kim-Mitsuyama, Shokei; Ogawa, Hisao

2015-04-01

Mitochondrial dysfunction plays an important role in cellular senescence and impaired function of vascular endothelium, resulted in cardiovascular diseases. Telmisartan is a unique angiotensin II type I receptor blocker that has been shown to prevent cardiovascular events in high risk patients. AMP-activated protein kinase (AMPK) plays a critical role in mitochondrial biogenesis and endothelial function. This study assessed whether telmisartan enhances mitochondrial function and alters cellular functions via AMPK in human coronary artery endothelial cells (HCAECs). In cultured HCAECs, telmisartan significantly enhanced mitochondrial activity assessed by mitochondrial reductase activity and intracellular ATP production and increased the expression of mitochondria related genes. Telmisartan prevented cellular senescence and exhibited the anti-apoptotic and pro-angiogenic properties. The expression of genes related anti-oxidant and pro-angiogenic properties were increased by telmisartan. Telmisartan increased endothelial NO synthase and AMPK phosphorylation. Peroxisome proliferator-activated receptor gamma signaling was not involved in telmisartan-induced improvement of mitochondrial function. All of these effects were abolished by inhibition of AMPK. Telmisartan enhanced mitochondrial activity and exhibited anti-senescence effects and improving endothelial function through AMPK in HCAECs. Telmisartan could provide beneficial effects on vascular diseases via enhancement of mitochondrial activity and modulating endothelial function through AMPK activation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Oxygen Glucose Deprivation in Rat Hippocampal Slice Cultures Results in Alterations in Carnitine Homeostasis and Mitochondrial Dysfunction

PubMed Central

Rau, Thomas F.; Lu, Qing; Sharma, Shruti; Sun, Xutong; Leary, Gregory; Beckman, Matthew L.; Hou, Yali; Wainwright, Mark S.; Kavanaugh, Michael; Poulsen, David J.; Black, Stephen M.

2012-01-01

Mitochondrial dysfunction characterized by depolarization of mitochondrial membranes and the initiation of mitochondrial-mediated apoptosis are pathological responses to hypoxia-ischemia (HI) in the neonatal brain. Carnitine metabolism directly supports mitochondrial metabolism by shuttling long chain fatty acids across the inner mitochondrial membrane for beta-oxidation. Our previous studies have shown that HI disrupts carnitine homeostasis in neonatal rats and that L-carnitine can be neuroprotective. Thus, this study was undertaken to elucidate the molecular mechanisms by which HI alters carnitine metabolism and to begin to elucidate the mechanism underlying the neuroprotective effect of L-carnitine (LCAR) supplementation. Utilizing neonatal rat hippocampal slice cultures we found that oxygen glucose deprivation (OGD) decreased the levels of free carnitines (FC) and increased the acylcarnitine (AC): FC ratio. These changes in carnitine homeostasis correlated with decreases in the protein levels of carnitine palmitoyl transferase (CPT) 1 and 2. LCAR supplementation prevented the decrease in CPT1 and CPT2, enhanced both FC and the AC∶FC ratio and increased slice culture metabolic viability, the mitochondrial membrane potential prior to OGD and prevented the subsequent loss of neurons during later stages of reperfusion through a reduction in apoptotic cell death. Finally, we found that LCAR supplementation preserved the structural integrity and synaptic transmission within the hippocampus after OGD. Thus, we conclude that LCAR supplementation preserves the key enzymes responsible for maintaining carnitine homeostasis and preserves both cell viability and synaptic transmission after OGD. PMID:22984394

Aspirin Increases Mitochondrial Fatty Acid Oxidation

PubMed Central

Uppala, Radha; Dudiak, Brianne; Beck, Megan E.; Bharathi, Sivakama S.; Zhang, Yuxun; Stolz, Donna B.; Goetzman, Eric S.

2016-01-01

The metabolic effects of salicylates are poorly understood. This study investigated the effects of aspirin on fatty acid oxidation. Aspirin increased mitochondrial long-chain fatty acid oxidation, but inhibited peroxisomal fatty acid oxidation, in two different cell lines. Aspirin increased mitochondrial protein acetylation and was found to be a stronger acetylating agent in vitro than acetyl-CoA. However, aspirin-induced acetylation did not alter the activity of fatty acid oxidation proteins, and knocking out the mitochondrial deacetylase SIRT3 did not affect the induction of long-chain fatty acid oxidation by aspirin. Aspirin did not change oxidation of medium-chain fatty acids, which can freely traverse the mitochondrial membrane. Together, these data indicate that aspirin does not directly alter mitochondrial matrix fatty acid oxidation enzymes, but most likely exerts its effects at the level of long-chain fatty acid transport into mitochondria. The drive on mitochondrial fatty acid oxidation may be a compensatory response to altered mitochondrial morphology and inhibited electron transport chain function, both of which were observed after 24 hr incubation of cells with aspirin. These studies provide insight into the pathophysiology of Reye Syndrome, which is known to be triggered by aspirin ingestion in patients with fatty acid oxidation disorders. PMID:27856258

L-beta-ODAP alters mitochondrial Ca2+ handling as an early event in excitotoxicity.

PubMed

Van Moorhem, Marijke; Decrock, Elke; Coussee, Evelyne; Faes, Liesbeth; De Vuyst, Elke; Vranckx, Katleen; De Bock, Marijke; Wang, Nan; D'Herde, Katharina; Lambein, Fernand; Callewaert, Geert; Leybaert, Luc

2010-03-01

The neurotoxin beta-N-oxalyl-L-alpha,beta-diaminopropionic acid (L-beta-ODAP) is an L-glutamate analogue at alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate receptors in neurons and therefore acts as an excitotoxic substance. Chronic exposure to L-beta-ODAP present in Lathyrus sativus L. (L. sativus) seeds is proposed as the cause of the neurodegenerative disease neurolathyrism, but the mechanism of its action has not been conclusively identified. A key factor in excitotoxic neuronal cell death is a disturbance of the intracellular Ca2+ homeostasis, including changes in the capacity of intracellular Ca2+ stores like the endoplasmic reticulum (ER) or mitochondria. In this study, aequorin and other Ca2+ indicators were used in N2a neuroblastoma cells to investigate alterations of cellular Ca2+ handling after 24 h exposure to L-beta-ODAP. Our data demonstrate increased mitochondrial Ca2+ loading and hyperpolarization of the mitochondrial membrane potential (Psi(m)), which was specific for L-beta-ODAP and not observed with L-glutamate. We conclude that L-beta-ODAP disturbs the ER-mitochondrial Ca2+ signaling axis and thereby renders the cells more vulnerable to its excitotoxic effects that ultimately will lead to cell death. 2010 Elsevier Ltd. All rights reserved.

Mitochondrial myopathies.

PubMed

DiMauro, Salvatore

2006-11-01

Our understanding of mitochondrial diseases (defined restrictively as defects of the mitochondrial respiratory chain) is expanding rapidly. In this review, I will give the latest information on disorders affecting predominantly or exclusively skeletal muscle. The most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency and mutations in genes controlling mitochondrial DNA abundance and structure, such as POLG, TK2, and MPV17. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with decreased amount and altered structure of cardiolipin, the main phospholipid of the inner mitochondrial membrane, but a secondary impairment of respiratory chain function is plausible. The role of mutations in protein-coding genes of mitochondrial DNA in causing isolated myopathies has been confirmed. Mutations in tRNA genes of mitochondrial DNA can also cause predominantly myopathic syndromes and--contrary to conventional wisdom--these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

Dietary alterations of the mitochondrial lipid pattern

PubMed Central

Sheltawy, A.

1965-01-01

1. Changes in the lipid composition of rat-liver mitochondria from both sexes have been studied in response to normal, fat and fat–cholesterol diets. The cholesterol added to the diet was in low concentrations (0·2%). 2. In the non-phospholipid fraction, normal females had higher mitochondrial cholesterol concentrations than males, and the concentration of the free sterol was decreased in fat–cholesterol-fed females, but not in males. 3. In the phospholipid fraction, normal rats of both sexes had a predominance of mitochondrial lecithin over other phosphatides, but females had slightly higher lecithin concentrations than males. Fat–cholesterol-fed females had equal concentrations of lecithin and kephalin. 4. In the minor phosphatides, normal males had higher concentrations of phosphoinositides than females. The phosphatidic acid plus polyglycerophosphatide concentration was increased above normal in fat-fed females. Fat–cholesterol-fed females had higher concentrations of phosphoinositides than normal. 5. In general, changes in the mitochondrial lipid fractions occurred in female but not in male rats. PMID:14340108

Mitochondrial genes are altered in blood early in Alzheimer's disease.

PubMed

Lunnon, Katie; Keohane, Aoife; Pidsley, Ruth; Newhouse, Stephen; Riddoch-Contreras, Joanna; Thubron, Elisabeth B; Devall, Matthew; Soininen, Hikka; Kłoszewska, Iwona; Mecocci, Patrizia; Tsolaki, Magda; Vellas, Bruno; Schalkwyk, Leonard; Dobson, Richard; Malik, Afshan N; Powell, John; Lovestone, Simon; Hodges, Angela

2017-05-01

Although mitochondrial dysfunction is a consistent feature of Alzheimer's disease in the brain and blood, the molecular mechanisms behind these phenomena are unknown. Here we have replicated our previous findings demonstrating reduced expression of nuclear-encoded oxidative phosphorylation (OXPHOS) subunits and subunits required for the translation of mitochondrial-encoded OXPHOS genes in blood from people with Alzheimer's disease and mild cognitive impairment. Interestingly this was accompanied by increased expression of some mitochondrial-encoded OXPHOS genes, namely those residing closest to the transcription start site of the polycistronic heavy chain mitochondrial transcript (MT-ND1, MT-ND2, MT-ATP6, MT-CO1, MT-CO2, MT-C03) and MT-ND6 transcribed from the light chain. Further we show that mitochondrial DNA copy number was unchanged suggesting no change in steady-state numbers of mitochondria. We suggest that an imbalance in nuclear and mitochondrial genome-encoded OXPHOS transcripts may drive a negative feedback loop reducing mitochondrial translation and compromising OXPHOS efficiency, which is likely to generate damaging reactive oxygen species. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

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.

Mitochondrial DNA plays an equal role in influencing female and male longevity in centenarians.

PubMed

He, Yong-Han; Lu, Xiang; Tian, Jiao-Yang; Yan, Dong-Jing; Li, Yu-Chun; Lin, Rong; Perry, Benjamin; Chen, Xiao-Qiong; Yu, Qin; Cai, Wang-Wei; Kong, Qing-Peng

2016-10-01

The mitochondrion is a double membrane-bound organelle which plays important functional roles in aging and many other complex phenotypes. Transmission of the mitochondrial genome in the matrilineal line causes the evolutionary selection sieve only in females. Theoretically, beneficial or neutral variations are more likely to accumulate and be retained in the female mitochondrial genome during evolution, which may be an initial trigger of gender dimorphism in aging. The asymmetry of evolutionary processes between gender could lead to males and females aging in different ways. If so, gender specific variation loads could be an evolutionary result of maternal heritage of mitochondrial genomes, especially in centenarians who live to an extreme age and are considered as good models for healthy aging. Here, we tested whether the mitochondrial variation loads were associated with altered aging patterns by investigating the mtDNA haplogroup distribution and genetic diversity between female and male centenarians. We found no evidence of differences in aging patterns between genders in centenarians. Our results indicate that the evolutionary consequence of gender dimorphism in mitochondrial genomes is not a factor in the altered aging patterns in human, and that mitochondrial DNA contributes equally to longevity in males and females. Copyright © 2016 Elsevier Inc. All rights reserved.

Altered sterol metabolism in budding yeast affects mitochondrial iron-sulfur (Fe-S) cluster synthesis.

PubMed

Ward, Diane M; Chen, Opal S; Li, Liangtao; Kaplan, Jerry; Bhuiyan, Shah Alam; Natarajan, Selvamuthu K; Bard, Martin; Cox, James E

2018-05-17

Ergosterol synthesis is essential for cellular growth and viability of the budding yeast Saccharomyces cerevisiae, and intracellular sterol distribution and homeostasis are therefore highly regulated in this species. Erg25 is an iron-containing C4-methyl sterol oxidase that contributes to the conversion of 4,4-dimethylzymosterol to zymosterol, a precursor of ergosterol. The ERG29 gene encodes an endoplasmic reticulum (ER)-associated protein, and here we identified a role for Erg29 in the methyl sterol oxidase step of ergosterol synthesis. ERG29 deletion resulted in lethality in respiring cells, but respiration-incompetent (Rho- or Rho0) cells survived, suggesting that Erg29 loss leads to accumulation of oxidized sterol metabolites that affect cell viability. Down-regulation of ERG29 expression in Δerg29 cells indeed led to accumulation of methyl sterol metabolites, resulting in increased mitochondrial oxidants and a decreased ability of mitochondria to synthesize iron-sulfur (Fe-S) clusters due to reduced levels of Yfh1, the mammalian frataxin homolog, which is involved in mitochondrial Fe metabolism. Using a high-copy genomic library, we identified suppressor genes that permitted growth of Δerg29 cells on respiratory substrates, and these included genes encoding the mitochondrial proteins Yfh1, Mmt1, Mmt2, and Pet20, which reversed all phenotypes associated with loss of ERG29. Of note, loss of Erg25 also resulted in accumulation of methyl sterol metabolites and also increased mitochondrial oxidants and degradation of Yfh1. We propose that accumulation of toxic intermediates of the methyl sterol oxidase reaction increase mitochondrial oxidants, which affect Yfh1 protein stability. These results indicate an interaction between sterols generated by ER proteins and mitochondrial iron metabolism. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Mitochondrial Dysfunction in Chemotherapy-Induced Peripheral Neuropathy (CIPN)

PubMed Central

Canta, Annalisa; Pozzi, Eleonora; Carozzi, Valentina Alda

2015-01-01

The mitochondrial dysfunction has a critical role in several disorders including chemotherapy-induced peripheral neuropathies (CIPN). This is due to a related dysregulation of pathways involving calcium signalling, reactive oxygen species and apoptosis. Vincristine is able to affect calcium movement through the Dorsal Root Ganglia (DRG) neuronal mitochondrial membrane, altering its homeostasis and leading to abnormal neuronal excitability. Paclitaxel induces the opening of the mitochondrial permeability transition pore in axons followed by mitochondrial membrane potential loss, increased reactive oxygen species generation, ATP level reduction, calcium release and mitochondrial swelling. Cisplatin and oxaliplatin form adducts with mitochondrial DNA producing inhibition of replication, disruption of transcription and morphological abnormalities within mitochondria in DRG neurons, leading to a gradual energy failure. Bortezomib is able to modify mitochondrial calcium homeostasis and mitochondrial respiratory chain. Moreover, the expression of a certain number of genes, including those controlling mitochondrial functions, was altered in patients with bortezomib-induced peripheral neuropathy. PMID:29056658

In Vitro Monitoring of the Mitochondrial Beta-Oxidation Flux of Palmitic Acid and Investigation of Its Pharmacological Alteration by Therapeutics.

PubMed

Murgasova, Renata; Tor Carreras, Ester; Bourgailh, Julien

2018-05-03

The present study was designed to validate the functional assay that enables rapid screening of therapeutic candidates for their effect on mitochondrial fatty acid oxidation. The two whole-cell systems (tissue homogenates and hepatocytes) have been evaluated to monitor the total beta-oxidation flux of physiologically important 3 H-palmitic acid by measurement of tritiated water enrichment in incubations using UPLC coupled on-line to radioactivity monitoring and mass spectrometry. Our results with several known inhibitors of fatty acid oxidation showed that this simple assay could correctly predict a potential in alteration of mitochondrial function by drug candidates. Since the beta-oxidation of palmitic acid takes place almost exclusively in mitochondria of human hepatocytes, this model can be also utilized to distinguish between the mitochondrial and peroxisomal routes of this essential metabolic pathway in some cases. The present work offers a new in vitro screen of changes in mitochondrial beta-oxidation by xenobiotics as well as a model to study the mechanism of this pathway.

Tissue specific distribution of pyrimidine deoxynucleoside salvage enzymes shed light on the mechanism of mitochondrial DNA depletion.

PubMed

Wang, L; Eriksson, S

2010-06-01

Deficiency in thymidine kinase 2 (TK2) activity due to genetic alterations caused tissue specific mitochondrial DNA (mtDNA) depletion syndrome with symptoms resembling these of AIDS patients treated with nucleoside analogues. Mechanisms behind this mitochondrial effects is still not well understood. With rat as a model we isolated mitochondrial and cytosolic fractions from major organs and studied enzymes involved in thymidine (dT) and deoxycytidine (dC) phosphorylation by using ionic exchange column chromatography. A cytosolic form of TK2 was identified in all tested tissues in addition to mitochondrial TK2. TK1 was detected in liver and spleen cytosolic extracts while dCK was found in liver, spleen and lung cytosolic extracts. Thus, the nature of dT and dC salvage enzymes in each tissue type was determined. In most tissues TK2 is the only salvage enzyme present except liver and spleen. These results may help to explain the mechanisms of mitochondrial toxicity of antiviral nucleoside analogues and mtDNA depletion caused by TK2 deficiency.

Kalpaamruthaa ameliorates mitochondrial and metabolic alterations in diabetes mellitus induced cardiovascular damage.

PubMed

Latha, Raja; Shanthi, Palanivelu; Sachdanandam, Panchanadham

2014-12-01

Efficacy of Kalpaamruthaa on the activities of lipid and carbohydrate metabolic enzymes, electron transport chain complexes and mitochondrial ATPases were studied in heart and liver of experimental rats. Cardiovascular damage (CVD) was developed in 8 weeks after type 2 diabetes mellitus induction with high fat diet (2 weeks) and low dose of streptozotocin (2 × 35 mg/kg b.w. i.p. in 24 hr interval). In CVD-induced rats, the activities of total lipase, cholesterol ester hydrolase and cholesterol ester synthetase were increased, while lipoprotein lipase and lecithin-cholesterol acyltransferase activities were decreased. The activities of lipid-metabolizing enzymes were altered by Kalpaamruthaa in CVD-induced rats towards normal. Kalpaamruthaa modulated the activities of glycolytic enzymes (hexokinase, phosphogluco-isomerase, aldolase and glucose-6-phosphate dehydrogenase), gluconeogenic enzymes (glucose-6-phosphatase and fructose-1, 6-bisphosphatase) and glycogenolytic enzyme (glycogen phosphorylase) along with increased glycogen content in the liver of CVD-induced rats. The activities of isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, α-ketoglutarate dehydrogenase, Complexes and ATPases (Na(+)/K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase) were decreased in CVD-induced rats, which were ameliorated by the treatment with Kalpaamruthaa. This study ascertained the efficacy of Kalpaamruthaa for the treatment of CVD in diabetes through the modulation of metabolizing enzymes and mitochondrial dysfunction.

Homeostatic effect of p-chloro-diphenyl diselenide on glucose metabolism and mitochondrial function alterations induced by monosodium glutamate administration to rats.

PubMed

Quines, Caroline B; Rosa, Suzan G; Chagas, Pietro M; da Rocha, Juliana T; Dobrachinski, Fernando; Carvalho, Nélson R; Soares, Félix A; da Luz, Sônia C Almeida; Nogueira, Cristina W

2016-01-01

The metabolic syndrome is a group of metabolic alterations considered a worldwide public health problem. Organic selenium compounds have been reported to have many different pharmacological actions, such as anti-hypercholesterolemic and anti-hyperglycemic. The aim of this study was to evaluate the effect of p-chloro-diphenyl diselenide (p-ClPhSe)2, an organic selenium compound, in a model of obesity induced by monosodium glutamate (MSG) administration in rats. The rats were treated during the first ten postnatal days with MSG and received (p-ClPhSe)2 (10 mg/kg, intragastrically) from 45th to 51 th postnatal day. Glucose, lipid and lactate levels were determined in plasma of rats. Glycogen levels and activities of tyrosine aminotransferase, hexokinase, citrate synthase and glucose-6-phosphatase (G-6-Pase) were determined in livers of rats. Renal G-6-Pase activity was also determined. The purine content [Adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate] and mitochondrial functionality in the liver were also investigated. p-(ClPhSe)2 did not alter the reduction in growth performance and in the body weight caused by MSG but reduced epididymal fat deposition of rats. p-(ClPhSe)2 restored glycemia, triglycerides, cholesterol and lactate levels as well as the glucose metabolism altered in rats treated with MSG. p-(ClPhSe)2 restored hepatic mitochondrial dysfunction and the decrease in citrate synthase activity and ATP and ADP levels caused by MSG in rats. In summary, (p-ClPhSe)2 had homeostatic effects on glucose metabolism and mitochondrial function alterations induced by MSG administration to rats.

Exposure of rats to environmental tobacco smoke during cerebellar development alters behavior and perturbs mitochondrial energetics.

PubMed

Fuller, Brian F; Cortes, Diego F; Landis, Miranda K; Yohannes, Hiyab; Griffin, Hailey E; Stafflinger, Jillian E; Bowers, M Scott; Lewis, Mark H; Fox, Michael A; Ottens, Andrew K

2012-12-01

Environmental tobacco smoke (ETS) exposure is linked to developmental deficits and disorders with known cerebellar involvement. However, direct biological effects and underlying neurochemical mechanisms remain unclear. We sought to identify and evaluate underlying neurochemical change in the rat cerebellum with ETS exposure during critical period development. We exposed rats to daily ETS (300, 100, and 0 µg/m3 total suspended particulate) from postnatal day 8 (PD8) to PD23 and then assayed the response at the behavioral, neuroproteomic, and cellular levels. Postnatal ETS exposure induced heightened locomotor response in a novel environment on par initially with amphetamine stimulation. The cerebellar mitochondrial subproteome was significantly perturbed in the ETS-exposed rats. Findings revealed a dose-dependent up-regulation of aerobic processes through the modification and increased translocation of Hk1 to the mitochondrion with corresponding heightened ATP synthase expression. ETS exposure also induced a dose-dependent increase in total Dnm1l mitochondrial fission factor; although more active membrane-bound Dnm1l was found at the lower dose. Dnm1l activation was associated with greater mitochondrial staining, particularly in the molecular layer, which was independent of stress-induced Bcl-2 family dynamics. Further, electron microscopy associated Dnm1l-mediated mitochondrial fission with increased biogenesis, rather than fragmentation. The critical postnatal period of cerebellar development is vulnerable to the effects of ETS exposure, resulting in altered behavior. The biological effect of ETS is underlain in part by a Dnm1l-mediated mitochondrial energetic response at a time of normally tight control. These findings represent a novel mechanism by which environmental exposure can impact neurodevelopment and function.

Alteration of ROS Homeostasis and Decreased Lifespan in S. cerevisiae Elicited by Deletion of the Mitochondrial Translocator FLX1

PubMed Central

Giancaspero, Teresa Anna; Dipalo, Emilia; Miccolis, Angelica; Boles, Eckhard; Caselle, Michele; Barile, Maria

2014-01-01

This paper deals with the control exerted by the mitochondrial translocator FLX1, which catalyzes the movement of the redox cofactor FAD across the mitochondrial membrane, on the efficiency of ATP production, ROS homeostasis, and lifespan of S. cerevisiae. The deletion of the FLX1 gene resulted in respiration-deficient and small-colony phenotype accompanied by a significant ATP shortage and ROS unbalance in glycerol-grown cells. Moreover, the flx1Δ strain showed H2O2 hypersensitivity and decreased lifespan. The impaired biochemical phenotype found in the flx1Δ strain might be justified by an altered expression of the flavoprotein subunit of succinate dehydrogenase, a key enzyme in bioenergetics and cell regulation. A search for possible cis-acting consensus motifs in the regulatory region upstream SDH1-ORF revealed a dozen of upstream motifs that might respond to induced metabolic changes by altering the expression of Flx1p. Among these motifs, two are present in the regulatory region of genes encoding proteins involved in flavin homeostasis. This is the first evidence that the mitochondrial flavin cofactor status is involved in controlling the lifespan of yeasts, maybe by changing the cellular succinate level. This is not the only case in which the homeostasis of redox cofactors underlies complex phenotypical behaviours, as lifespan in yeasts. PMID:24895546

Defects in Mitochondrial Dynamics and Metabolomic Signatures of Evolving Energetic Stress in Mouse Models of Familial Alzheimer's Disease

PubMed Central

Trushina, Eugenia; Nemutlu, Emirhan; Zhang, Song; Christensen, Trace; Camp, Jon; Mesa, Janny; Siddiqui, Ammar; Tamura, Yasushi; Sesaki, Hiromi; Wengenack, Thomas M.; Dzeja, Petras P.; Poduslo, Joseph F.

2012-01-01

Background The identification of early mechanisms underlying Alzheimer's Disease (AD) and associated biomarkers could advance development of new therapies and improve monitoring and predicting of AD progression. Mitochondrial dysfunction has been suggested to underlie AD pathophysiology, however, no comprehensive study exists that evaluates the effect of different familial AD (FAD) mutations on mitochondrial function, dynamics, and brain energetics. Methods and Findings We characterized early mitochondrial dysfunction and metabolomic signatures of energetic stress in three commonly used transgenic mouse models of FAD. Assessment of mitochondrial motility, distribution, dynamics, morphology, and metabolomic profiling revealed the specific effect of each FAD mutation on the development of mitochondrial stress and dysfunction. Inhibition of mitochondrial trafficking was characteristic for embryonic neurons from mice expressing mutant human presenilin 1, PS1(M146L) and the double mutation of human amyloid precursor protein APP(Tg2576) and PS1(M146L) contributing to the increased susceptibility of neurons to excitotoxic cell death. Significant changes in mitochondrial morphology were detected in APP and APP/PS1 mice. All three FAD models demonstrated a loss of the integrity of synaptic mitochondria and energy production. Metabolomic profiling revealed mutation-specific changes in the levels of metabolites reflecting altered energy metabolism and mitochondrial dysfunction in brains of FAD mice. Metabolic biomarkers adequately reflected gender differences similar to that reported for AD patients and correlated well with the biomarkers currently used for diagnosis in humans. Conclusions Mutation-specific alterations in mitochondrial dynamics, morphology and function in FAD mice occurred prior to the onset of memory and neurological phenotype and before the formation of amyloid deposits. Metabolomic signatures of mitochondrial stress and altered energy metabolism indicated

Evaluation of the water disinfection by-product dichloroacetonitrile-induced biochemical, oxidative, histopathological, and mitochondrial functional alterations: Subacute oral toxicity in rats.

PubMed

Dong, Ying; Li, Fang; Shen, Haijun; Lu, Rongzhu; Yin, Siqi; Yang, Qi; Li, Zhuangfa; Wang, Suhua

2018-03-01

Dichloroacetonitrile (DCAN), an emerging nitrogenous disinfection by-product, is more genotoxic and cytotoxic than the currently regulated carbonaceous disinfection by-products such as haloacetic acids. Few mechanistic studies have been conducted on the hepatic and renal toxicities of DCAN. This study examined the clinical biochemical, hematological, histopathological, oxidative, and mitochondrial functional alterations to evaluate the systematic toxicity after subacute oral exposure of 11 or 44 mg/kg/day in rats for 28 days. Body and spleen weights were lower, and organ-to-body weight ratios of the liver and kidney were higher in rats administered 44-mg/kg DCAN than in controls. The activities of serum alanine aminotransferase and alkaline phosphatase, and concentrations of blood serum urea nitrogen and retinol-binding protein were increased in rats administered 44-mg/kg DCAN compared with those of controls, thereby indicating hepatic and renal damage in this group. This was confirmed by histopathological alterations, including hepatic sinus dilation, extensive hemorrhage, vacuolar degeneration in the liver and glomerulus hemorrhage, and renal tubular swelling, in DCAN-exposed rats. Exposure to 44-mg/kg DCAN induced hepatic oxidative damage shown by the significant increase in malonaldehyde levels, a poisonous product of lipid peroxidation. Exposure to 44-mg/kg DCAN significantly increased hepatic glutathione content and mitochondrial bioenergy as noted by the elevation of mitochondrial membrane potential and cytochrome c oxidase activity, which might be attributed to compensatory pathophysiologic responses to DCAN-induced hepatic mitochondrial damage.

Mutations in nuclear genes alter post-transcriptional regulation of mitochondrial genes.

USDA-ARS?s Scientific Manuscript database

Nuclear gene products are required for the expression of mitochondrial genes and elaboration of functional mitochondrial protein complexes. To better understand the roles of these nuclear genes, we exploited the mitochondrial encoded S-type of cytoplasmic male sterility (CMS-S) and developed a nove...

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.

The Biarylpyrazole Compound AM251 Alters Mitochondrial Physiology via Proteolytic Degradation of ERRα

PubMed Central

Krzysik-Walker, Susan M.; González-Mariscal, Isabel; Scheibye-Knudsen, Morten; Indig, Fred E.

2013-01-01

The orphan nuclear receptor estrogen-related receptor alpha (ERRα) directs the transcription of nuclear genes involved in energy homeostasis control and the regulation of mitochondrial mass and function. A crucial role for controlling ERRα-mediated target gene expression has been ascribed to the biarylpyrazole compound 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide (AM251) through direct binding to and destabilization of ERRα protein. Here, we provide evidence that structurally related AM251 analogs also have negative impacts on ERRα protein levels in a cell-type-dependent manner while having no deleterious actions on ERRγ. We show that these off-target cellular effects of AM251 are mediated by proteasomal degradation of nuclear ERRα. Cell treatment with the nuclear export inhibitor leptomycin B did not prevent AM251-induced destabilization of ERRα protein, whereas proteasome inhibition with MG132 stabilized and maintained its DNA-binding function, indicative of ERRα being a target of nuclear proteasomal complexes. NativePAGE analysis revealed that ERRα formed a ∼220-kDa multiprotein nuclear complex that was devoid of ERRγ and the coregulator peroxisome proliferator-activated receptor γ coactivator-1. AM251 induced SUMO-2,3 incorporation in ERRα in conjunction with increased protein kinase C activity, whose activation by phorbol ester also promoted ERRα protein loss. Down-regulation of ERRα by AM251 or small interfering RNA led to increased mitochondria biogenesis while negatively impacting mitochondrial membrane potential. These results reveal a novel molecular mechanism by which AM251 and related compounds alter mitochondrial physiology through destabilization of ERRα. PMID:23066093

Oxidative stress alters mitochondrial bioenergetics and modifies pancreatic cell death independently of cyclophilin D, resulting in an apoptosis-to-necrosis shift

PubMed Central

Armstrong, Jane A.; Cash, Nicole J.; Ouyang, Yulin; Morton, Jack C.; Chvanov, Michael; Latawiec, Diane; Awais, Muhammad; Tepikin, Alexei V.; Sutton, Robert; Criddle, David N.

2018-01-01

Mitochondrial dysfunction lies at the core of acute pancreatitis (AP). Diverse AP stimuli induce Ca2+-dependent formation of the mitochondrial permeability transition pore (MPTP), a solute channel modulated by cyclophilin D (CypD), the formation of which causes ATP depletion and necrosis. Oxidative stress reportedly triggers MPTP formation and is elevated in clinical AP, but how reactive oxygen species influence cell death is unclear. Here, we assessed potential MPTP involvement in oxidant-induced effects on pancreatic acinar cell bioenergetics and fate. H2O2 application promoted acinar cell apoptosis at low concentrations (1–10 μm), whereas higher levels (0.5–1 mm) elicited rapid necrosis. H2O2 also decreased the mitochondrial NADH/FAD+ redox ratio and ΔΨm in a concentration-dependent manner (10 μm to 1 mm H2O2), with maximal effects at 500 μm H2O2. H2O2 decreased the basal O2 consumption rate of acinar cells, with no alteration of ATP turnover at <50 μm H2O2. However, higher H2O2 levels (≥50 μm) diminished spare respiratory capacity and ATP turnover, and bioenergetic collapse, ATP depletion, and cell death ensued. Menadione exerted detrimental bioenergetic effects similar to those of H2O2, which were inhibited by the antioxidant N-acetylcysteine. Oxidant-induced bioenergetic changes, loss of ΔΨm, and cell death were not ameliorated by genetic deletion of CypD or by its acute inhibition with cyclosporine A. These results indicate that oxidative stress alters mitochondrial bioenergetics and modifies pancreatic acinar cell death. A shift from apoptosis to necrosis appears to be associated with decreased mitochondrial spare respiratory capacity and ATP production, effects that are independent of CypD-sensitive MPTP formation. PMID:29626097

Mitochondrial diversity and distribution of African green monkeys (chlorocebus gray, 1870).

PubMed

Haus, Tanja; Akom, Emmanuel; Agwanda, Bernard; Hofreiter, Michael; Roos, Christian; Zinner, Dietmar

2013-04-01

African green monkeys (Chlorocebus) represent a widely distributed and morphologically diverse primate genus in sub-Saharan Africa. Little attention has been paid to their genetic diversity and phylogeny. Based on morphological data, six species are currently recognized, but their taxonomy remains disputed. Here, we aim to characterize the mitochondrial (mt) DNA diversity, biogeography and phylogeny of African green monkeys. We analyzed the complete mitochondrial cytochrome b gene of 126 samples using feces from wild individuals and material from zoo and museum specimens with clear geographical provenance, including several type specimens. We found evidence for nine major mtDNA clades that reflect geographic distributions rather than taxa, implying that the mtDNA diversity of African green monkeys does not conform to existing taxonomic classifications. Phylogenetic relationships among clades could not be resolved suggesting a rapid early divergence of lineages. Several discordances between mtDNA and phenotype indicate that hybridization may have occurred in contact zones among species, including the threatened Bale monkey (Chlorocebus djamdjamensis). Our results provide both valuable data on African green monkeys' genetic diversity and evolution and a basis for further molecular studies on this genus. © 2013 Wiley Periodicals, Inc.

Targeted transgenic overexpression of mitochondrial thymidine kinase (TK2) alters mitochondrial DNA (mtDNA) and mitochondrial polypeptide abundance: transgenic TK2, mtDNA, and antiretrovirals.

PubMed

Hosseini, Seyed H; Kohler, James J; Haase, Chad P; Tioleco, Nina; Stuart, Tami; Keebaugh, Erin; Ludaway, Tomika; Russ, Rodney; Green, Elgin; Long, Robert; Wang, Liya; Eriksson, Staffan; Lewis, William

2007-03-01

Mitochondrial toxicity limits nucleoside reverse transcriptase inhibitors (NRTIs) for acquired immune deficiency syndrome. NRTI triphosphates, the active moieties, inhibit human immunodeficiency virus reverse transcriptase and eukaryotic mitochondrial DNA polymerase pol-gamma. NRTI phosphorylation seems to correlate with mitochondrial toxicity, but experimental evidence is lacking. Transgenic mice (TGs) with cardiac overexpression of thymidine kinase isoforms (mitochondrial TK2 and cytoplasmic TK1) were used to study NRTI mitochondrial toxicity. Echocardiography and nuclear magnetic resonance imaging defined cardiac performance and structure. TK gene copy and enzyme activity, mitochondrial (mt) DNA and polypeptide abundance, succinate dehydrogenase and cytochrome oxidase histochemistry, and electron microscopy correlated with transgenesis, mitochondrial structure, and biogenesis. Antiretroviral combinations simulated therapy. Untreated hTK1 or TK2 TGs exhibited normal left ventricle mass. In TK2 TGs, cardiac TK2 gene copy doubled, activity increased 300-fold, and mtDNA abundance doubled. Abundance of the 17-kd subunit of complex I, succinate dehydrogenase histochemical activity, and cristae density increased. NRTIs increased left ventricle mass 20% in TK2 TGs. TK activity increased 3 logs in hTK1 TGs, but no cardiac phenotype resulted. NRTIs abrogated functional effects of transgenically increased TK2 activity but had no effect on TK2 mtDNA abundance. Thus, NRTI mitochondrial phosphorylation by TK2 is integral to clinical NRTI mitochondrial toxicity.

Mitochondrial tRNA cleavage by tRNA-targeting ribonuclease causes mitochondrial dysfunction observed in mitochondrial disease

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

Ogawa, Tetsuhiro, E-mail: atetsu@mail.ecc.u-tokyo.ac.jp; Shimizu, Ayano; Takahashi, Kazutoshi

2014-08-15

Highlights: • MTS-tagged ribonuclease was translocated successfully to the mitochondrial matrix. • MTS-tagged ribonuclease cleaved mt tRNA and reduced COX activity. • Easy and reproducible method of inducing mt tRNA dysfunction. - Abstract: Mitochondrial DNA (mtDNA) is a genome possessed by mitochondria. Since reactive oxygen species (ROS) are generated during aerobic respiration in mitochondria, mtDNA is commonly exposed to the risk of DNA damage. Mitochondrial disease is caused by mitochondrial dysfunction, and mutations or deletions on mitochondrial tRNA (mt tRNA) genes are often observed in mtDNA of patients with the disease. Hence, the correlation between mt tRNA activity and mitochondrialmore » dysfunction has been assessed. Then, cybrid cells, which are constructed by the fusion of an enucleated cell harboring altered mtDNA with a ρ{sup 0} cell, have long been used for the analysis due to difficulty in mtDNA manipulation. Here, we propose a new method that involves mt tRNA cleavage by a bacterial tRNA-specific ribonuclease. The ribonuclease tagged with a mitochondrial-targeting sequence (MTS) was successfully translocated to the mitochondrial matrix. Additionally, mt tRNA cleavage, which resulted in the decrease of cytochrome c oxidase (COX) activity, was observed.« less

Mitochondrial free cholesterol loading sensitizes to TNF- and Fas-mediated steatohepatitis.

PubMed

Marí, Montserrat; Caballero, Francisco; Colell, Anna; Morales, Albert; Caballeria, Juan; Fernandez, Anna; Enrich, Carlos; Fernandez-Checa, José C; García-Ruiz, Carmen

2006-09-01

The etiology of progression from steatosis to steatohepatitis (SH) remains unknown. Using nutritional and genetic models of hepatic steatosis, we show that free cholesterol (FC) loading, but not free fatty acids or triglycerides, sensitizes to TNF- and Fas-induced SH. FC distribution in endoplasmic reticulum (ER) and plasma membrane did not cause ER stress or alter TNF signaling. Rather, mitochondrial FC loading accounted for the hepatocellular sensitivity to TNF due to mitochondrial glutathione (mGSH) depletion. Selective mGSH depletion in primary hepatocytes recapitulated the susceptibility to TNF and Fas seen in FC-loaded hepatocytes; its repletion rescued FC-loaded livers from TNF-mediated SH. Moreover, hepatocytes from mice lacking NPC1, a late endosomal cholesterol trafficking protein, or from obese ob/ob mice, exhibited mitochondrial FC accumulation, mGSH depletion, and susceptibility to TNF. Thus, we propose a critical role for mitochondrial FC loading in precipitating SH, by sensitizing hepatocytes to TNF and Fas through mGSH depletion.

Metabolic Stress and Disorders Related to Alterations in Mitochondrial Fission or Fusion

PubMed Central

Babbar, Mansi; Sheikh, M. Saeed

2014-01-01

Mitochondrial morphology and metabolism play an important role in cellular homeostasis. Recent studies have shown that the fidelity of mitochondrial morphology is important in maintaining mitochondrial shape, number, size, membrane potential, ATP synthesis, mtDNA, motility, signaling, quality control, response to cellular stress, mitophagy and apoptosis. This article provides an overview of the current state of knowledge of the fission and fusion machinery with a focus on the mechanisms underlying the regulation of the mitochondrial morphology and cellular energy state. Several lines of evidence indicate that dysregulation of mitochondrial fission or fusion is associated with mitochondrial dysfunction, which in turn impacts mitophagy and apoptosis. Metabolic disorders are also associated with dysregulation of fission or fusion and the available lines of evidence point to a bidirectional interplay between the mitochondrial fission or fusion reactions and bioenergetics. Clearly, more in-depth studies are needed to fully elucidate the mechanisms that control mitochondrial fission and fusion. It is envisioned that the outcome of such studies will improve the understanding of the molecular basis of related metabolic disorders and also facilitate the development of better therapeutics. PMID:24533171

CED-9 and mitochondrial homeostasis in C. elegans muscle

PubMed Central

Tan, Frederick J.; Husain, Michelle; Manlandro, Cara Marie; Koppenol, Marijke; Fire, Andrew Z.; Hill, R. Blake

2009-01-01

Summary Mitochondrial homeostasis reflects a dynamic balance between membrane fission and fusion events thought essential for mitochondrial function. We report here that altered expression of the C. elegans BCL2 homolog CED-9 affects both mitochondrial fission and fusion. Although striated muscle cells lacking CED-9 have no alteration in mitochondrial size or ultrastructure, these cells appear more sensitive to mitochondrial fragmentation. By contrast, increased CED-9 expression in these cells produces highly interconnected mitochondria. This mitochondrial phenotype is partially suppressed by increased expression of the dynamin-related GTPase DRP-1, with suppression dependent on the BH3 binding pocket of CED-9. This suppression suggests that CED-9 directly regulates DRP-1, a model supported by our finding that CED-9 activates the GTPase activity of human DRP1. Thus, CED-9 is capable of regulating the mitochondrial fission-fusion cycle but is not essential for either fission or fusion. PMID:18827010

Spatial and temporal dynamics of the cardiac mitochondrial proteome.

PubMed

Lau, Edward; Huang, Derrick; Cao, Quan; Dincer, T Umut; Black, Caitie M; Lin, Amanda J; Lee, Jessica M; Wang, Ding; Liem, David A; Lam, Maggie P Y; Ping, Peipei

2015-04-01

Mitochondrial proteins alter in their composition and quantity drastically through time and space in correspondence to changing energy demands and cellular signaling events. The integrity and permutations of this dynamism are increasingly recognized to impact the functions of the cardiac proteome in health and disease. This article provides an overview on recent advances in defining the spatial and temporal dynamics of mitochondrial proteins in the heart. Proteomics techniques to characterize dynamics on a proteome scale are reviewed and the physiological consequences of altered mitochondrial protein dynamics are discussed. Lastly, we offer our perspectives on the unmet challenges in translating mitochondrial dynamics markers into the clinic.

Redox Regulation of Mitochondrial Function

PubMed Central

Handy, Diane E.

2012-01-01

Abstract Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function. Antioxid. Redox Signal. 16, 1323–1367. PMID:22146081

Mitochondrial lipids in neurodegeneration.

PubMed

Aufschnaiter, Andreas; Kohler, Verena; Diessl, Jutta; Peselj, Carlotta; Carmona-Gutierrez, Didac; Keller, Walter; Büttner, Sabrina

2017-01-01

Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer's or Parkinson's disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.

Altering the Mitochondrial Fatty Acid Synthesis (mtFASII) Pathway Modulates Cellular Metabolic States and Bioactive Lipid Profiles as Revealed by Metabolomic Profiling

PubMed Central

Clay, Hayley B.; Parl, Angelika K.; Mitchell, Sabrina L.; Singh, Larry; Bell, Lauren N.; Murdock, Deborah G.

2016-01-01

Despite the presence of a cytosolic fatty acid synthesis pathway, mitochondria have retained their own means of creating fatty acids via the mitochondrial fatty acid synthesis (mtFASII) pathway. The reason for its conservation has not yet been elucidated. Therefore, to better understand the role of mtFASII in the cell, we used thin layer chromatography to characterize the contribution of the mtFASII pathway to the fatty acid composition of selected mitochondrial lipids. Next, we performed metabolomic analysis on HeLa cells in which the mtFASII pathway was either hypofunctional (through knockdown of mitochondrial acyl carrier protein, ACP) or hyperfunctional (through overexpression of mitochondrial enoyl-CoA reductase, MECR). Our results indicate that the mtFASII pathway contributes little to the fatty acid composition of mitochondrial lipid species examined. Additionally, loss of mtFASII function results in changes in biochemical pathways suggesting alterations in glucose utilization and redox state. Interestingly, levels of bioactive lipids, including lysophospholipids and sphingolipids, directly correlate with mtFASII function, indicating that mtFASII may be involved in the regulation of bioactive lipid levels. Regulation of bioactive lipid levels by mtFASII implicates the pathway as a mediator of intracellular signaling. PMID:26963735

Changes in the mitochondrial network during ectromelia virus infection of permissive L929 cells.

PubMed

Gregorczyk, Karolina P; Szulc-Dąbrowska, Lidia; Wyżewski, Zbigniew; Struzik, Justyna; Niemiałtowski, Marek

2014-01-01

Mitochondria are extremely important organelles in the life of a cell. Recent studies indicate that mitochondria also play a fundamental role in the cellular innate immune mechanisms against viral infections. Moreover, mitochondria are able to alter their shape continuously through fusion and fission. These tightly regulated processes are activated or inhibited under physiological or pathological (e.g. viral infection) conditions to help restore homeostasis. However, many types of viruses, such as orthopoxviruses, have developed various strategies to evade the mitochondrial-mediated antiviral innate immune responses. Moreover, orthopoxviruses exploit the mitochondria for their survival. Such viral activity has been reported during vaccinia virus (VACV) infection. Our study shows that the Moscow strain of ectromelia virus (ECTV-MOS), an orthopoxvirus, alters the mitochondrial network in permissive L929 cells. Upon infection, the branching structure of the mitochondrial network collapses and becomes disorganized followed by destruction of mitochondrial tubules during the late stage of infection. Small, discrete mitochondria co-localize with progeny virions, close to the cell membrane. Furthermore, clustering of mitochondria is observed around viral factories, particularly between the nucleus and viroplasm. Our findings suggest that ECTV-MOS modulates mitochondrial cellular distribution during later stages of the replication cycle, probably enabling viral replication and/or assembly as well as transport of progeny virions inside the cell. However, this requires further investigation.

Mitochondrial DNA alteration in obstructive sleep apnea.

PubMed

Lacedonia, Donato; Carpagnano, Giovanna E; Crisetti, Elisabetta; Cotugno, Grazia; Palladino, Grazia P; Patricelli, Giulia; Sabato, Roberto; Foschino Barbaro, Maria P

2015-04-07

Obstructive Sleep Apnea (OSAS) is a disease associated with the increase of cardiovascular risk and it is characterized by repeated episodes of Intermittent Hypoxia (IH) which inducing oxidative stress and systemic inflammation. Mitochondria are cell organelles involved in the respiratory that have their own DNA (MtDNA). The aim of this study was to investigate if the increase of oxidative stress in OSAS patients can induce also MtDNA alterations. 46 OSAS patients (age 59.27 ± 11.38; BMI 30.84 ± 3.64; AHI 36.63 ± 24.18) were compared with 36 control subjects (age 54.42 ± 6.63; BMI 29.06 ± 4.7; AHI 3.8 ± 1.10). In blood cells Content of MtDNA and nuclear DNA (nDNA) was measured in OSAS patients by Real Time PCR. The ratio between MtDNA/nDNA was then calculated. Presence of oxidative stress was evaluated by levels of Reactive Oxygen Metabolites (ROMs), measured by diacron reactive oxygen metabolite test (d-ROM test). MtDNA/nDNA was higher in patients with OSAS than in the control group (150.94 ± 49.14 vs 128.96 ± 45.8; p = 0.04), the levels of ROMs were also higher in OSAS subjects (329.71 ± 70.17 vs 226 ± 36.76; p = 0.04) and they were positively correlated with MtDNA/nDNA (R = 0.5, p < 0.01). In OSAS patients there is a Mitochondrial DNA damage induced by the increase of oxidative stress. Intermittent hypoxia seems to be the main mechanism which leads to this process.

Integrated genomic analysis of mitochondrial RNA processing in human cancers.

PubMed

Idaghdour, Youssef; Hodgkinson, Alan

2017-04-18

The mitochondrial genome is transcribed as continuous polycistrons of RNA containing multiple genes. As a consequence, post-transcriptional events are critical for the regulation of gene expression and therefore all aspects of mitochondrial function. One particularly important process is the m 1 A/m 1 G RNA methylation of the ninth position of different mitochondrial tRNAs, which allows efficient processing of mitochondrial mRNAs and protein translation, and de-regulation of genes involved in these processes has been associated with altered mitochondrial function. Although mitochondria play a key role in cancer, the status of mitochondrial RNA processing in tumorigenesis is unknown. We measure and assess mitochondrial RNA processing using integrated genomic analysis of RNA sequencing and genotyping data from 1226 samples across 12 different cancer types. We focus on the levels of m 1 A and m 1 G RNA methylation in mitochondrial tRNAs in normal and tumor samples and use supervised and unsupervised statistical analysis to compare the levels of these modifications to patient whole genome genotypes, nuclear gene expression, and survival outcomes. We find significant changes to m 1 A and m 1 G RNA methylation levels in mitochondrial tRNAs in tumor tissues across all cancers. Pathways of RNA processing are strongly associated with methylation levels in normal tissues (P = 3.27 × 10 -31 ), yet these associations are lost in tumors. Furthermore, we report 18 gene-by-disease-state interactions where altered RNA methylation levels occur under cancer status conditional on genotype, implicating genes associated with mitochondrial function or cancer (e.g., CACNA2D2, LMO2, and FLT3) and suggesting that nuclear genetic variation can potentially modulate an individual's ability to maintain unaltered rates of mitochondrial RNA processing under cancer status. Finally, we report a significant association between the magnitude of methylation level changes in tumors and

Mitochondrial adaptations to physiological vs. pathological cardiac hypertrophy

PubMed Central

Abel, E. Dale; Doenst, Torsten

2011-01-01

Cardiac hypertrophy is a stereotypic response of the heart to increased workload. The nature of the workload increase may vary depending on the stimulus (repetitive, chronic, pressure, or volume overload). If the heart fully adapts to the new loading condition, the hypertrophic response is considered physiological. If the hypertrophic response is associated with the ultimate development of contractile dysfunction and heart failure, the response is considered pathological. Although divergent signalling mechanisms may lead to these distinct patterns of hypertrophy, there is some overlap. Given the close relationship between workload and energy demand, any form of cardiac hypertrophy will impact the energy generation by mitochondria, which are the key organelles for cellular ATP production. Significant changes in the expression of nuclear and mitochondrially encoded transcripts that impact mitochondrial function as well as altered mitochondrial proteome composition and mitochondrial energetics have been described in various forms of cardiac hypertrophy. Here, we review mitochondrial alterations in pathological and physiological hypertrophy. We suggest that mitochondrial adaptations to pathological and physiological hypertrophy are distinct, and we shall review potential mechanisms that might account for these differences. PMID:21257612

Dynamin-related Protein 1 Inhibition Mitigates Bisphenol A-mediated Alterations in Mitochondrial Dynamics and Neural Stem Cell Proliferation and Differentiation*

PubMed Central

Agarwal, Swati; Yadav, Anuradha; Tiwari, Shashi Kant; Seth, Brashket; Chauhan, Lalit Kumar Singh; Khare, Puneet; Ray, Ratan Singh

2016-01-01

The regulatory dynamics of mitochondria comprises well orchestrated distribution and mitochondrial turnover to maintain the mitochondrial circuitry and homeostasis inside the cells. Several pieces of evidence suggested impaired mitochondrial dynamics and its association with the pathogenesis of neurodegenerative disorders. We found that chronic exposure of synthetic xenoestrogen bisphenol A (BPA), a component of consumer plastic products, impaired autophagy-mediated mitochondrial turnover, leading to increased oxidative stress, mitochondrial fragmentation, and apoptosis in hippocampal neural stem cells (NSCs). It also inhibited hippocampal derived NSC proliferation and differentiation, as evident by the decreased number of BrdU- and β-III tubulin-positive cells. All these effects were reversed by the inhibition of oxidative stress using N-acetyl cysteine. BPA up-regulated the levels of Drp-1 (dynamin-related protein 1) and enhanced its mitochondrial translocation, with no effect on Fis-1, Mfn-1, Mfn-2, and Opa-1 in vitro and in the hippocampus. Moreover, transmission electron microscopy studies suggested increased mitochondrial fission and accumulation of fragmented mitochondria and decreased elongated mitochondria in the hippocampus of the rat brain. Impaired mitochondrial dynamics by BPA resulted in increased reactive oxygen species and malondialdehyde levels, disruption of mitochondrial membrane potential, and ATP decline. Pharmacological (Mdivi-1) and genetic (Drp-1siRNA) inhibition of Drp-1 reversed BPA-induced mitochondrial dysfunctions, fragmentation, and apoptosis. Interestingly, BPA-mediated inhibitory effects on NSC proliferation and neuronal differentiations were also mitigated by Drp-1 inhibition. On the other hand, Drp-1 inhibition blocked BPA-mediated Drp-1 translocation, leading to decreased apoptosis of NSC. Overall, our studies implicate Drp-1 as a potential therapeutic target against BPA-mediated impaired mitochondrial dynamics and

Metabolism alteration in follicular niche: The nexus among intermediary metabolism, mitochondrial function, and classic polycystic ovary syndrome.

PubMed

Zhao, Hongcui; Zhao, Yue; Li, Tianjie; Li, Min; Li, Junsheng; Li, Rong; Liu, Ping; Yu, Yang; Qiao, Jie

2015-09-01

Classic polycystic ovary syndrome (PCOS) is a high-risk phenotype accompanied by increased risks of reproductive and metabolic abnormalities; however, the local metabolism characteristics of the ovaries and their effects on germ cell development are unclear. The present study used targeted metabolomics to detect alterations in the intermediate metabolites of follicular fluid from classic PCOS patients, and the results indicated that hyperandrogenism but not obesity induced the changed intermediate metabolites in classic PCOS patients. Regarding the direct contact, we identified mitochondrial function, redox potential, and oxidative stress in cumulus cells which were necessary to support oocyte growth before fertilization, and suggested dysfunction of mitochondria, imbalanced redox potential, and increased oxidative stress in cumulus cells of classic PCOS patients. Follicular fluid intermediary metabolic profiles provide signatures of classic PCOS ovary local metabolism and establish a close link with mitochondria dysfunction of cumulus cells, highlighting the role of metabolic signal and mitochondrial cross talk involved in the pathogenesis of classic PCOS. Copyright © 2015 Elsevier Inc. All rights reserved.

Alteration of Fatty-Acid-Metabolizing Enzymes Affects Mitochondrial Form and Function in Hereditary Spastic Paraplegia

PubMed Central

Tesson, Christelle; Nawara, Magdalena; Salih, Mustafa A.M.; Rossignol, Rodrigue; Zaki, Maha S.; Al Balwi, Mohammed; Schule, Rebecca; Mignot, Cyril; Obre, Emilie; Bouhouche, Ahmed; Santorelli, Filippo M.; Durand, Christelle M.; Oteyza, Andrés Caballero; El-Hachimi, Khalid H.; Al Drees, Abdulmajeed; Bouslam, Naima; Lamari, Foudil; Elmalik, Salah A.; Kabiraj, Mohammad M.; Seidahmed, Mohammed Z.; Esteves, Typhaine; Gaussen, Marion; Monin, Marie-Lorraine; Gyapay, Gabor; Lechner, Doris; Gonzalez, Michael; Depienne, Christel; Mochel, Fanny; Lavie, Julie; Schols, Ludger; Lacombe, Didier; Yahyaoui, Mohamed; Al Abdulkareem, Ibrahim; Zuchner, Stephan; Yamashita, Atsushi; Benomar, Ali; Goizet, Cyril; Durr, Alexandra; Gleeson, Joseph G.; Darios, Frederic; Brice, Alexis; Stevanin, Giovanni

2012-01-01

Hereditary spastic paraplegia (HSP) is considered one of the most heterogeneous groups of neurological disorders, both clinically and genetically. The disease comprises pure and complex forms that clinically include slowly progressive lower-limb spasticity resulting from degeneration of the corticospinal tract. At least 48 loci accounting for these diseases have been mapped to date, and mutations have been identified in 22 genes, most of which play a role in intracellular trafficking. Here, we identified mutations in two functionally related genes (DDHD1 and CYP2U1) in individuals with autosomal-recessive forms of HSP by using either the classical positional cloning or a combination of whole-genome linkage mapping and next-generation sequencing. Interestingly, three subjects with CYP2U1 mutations presented with a thin corpus callosum, white-matter abnormalities, and/or calcification of the basal ganglia. These genes code for two enzymes involved in fatty-acid metabolism, and we have demonstrated in human cells that the HSP pathophysiology includes alteration of mitochondrial architecture and bioenergetics with increased oxidative stress. Our combined results focus attention on lipid metabolism as a critical HSP pathway with a deleterious impact on mitochondrial bioenergetic function. PMID:23176821

A Mitochondrial Mutator System in Maize1[w

PubMed Central

Kuzmin, Evgeny V.; Duvick, Donald N.; Newton, Kathleen J.

2005-01-01

The P2 line of maize (Zea mays) is characterized by mitochondrial genome destabilization, initiated by recessive nuclear mutations. These alleles alter copy number control of mitochondrial subgenomes and disrupt normal transfer of mitochondrial genomic components to progeny, resulting in differences in mitochondrial DNA profiles among sibling plants and between parents and progeny. The mitochondrial DNA changes are often associated with variably defective phenotypes, reflecting depletion of essential mitochondrial genes. The P2 nuclear genotype can be considered a natural mutagenesis system for maize mitochondria. It dramatically accelerates mitochondrial genomic divergence by increasing low copy-number subgenomes, by rapidly amplifying aberrant recombination products, and by causing the random loss of normal components of the mitochondrial genomes. PMID:15681663

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

Mitochondrial DNA Damage and its Consequences for Mitochondrial Gene Expression

PubMed Central

Cline, Susan D.

2012-01-01

How mitochondria process DNA damage and whether a change in the steady-state level of mitochondrial DNA damage (mtDNA) contributes to mitochondrial dysfunction are questions that fuel burgeoning areas of research into aging and disease pathogenesis. Over the past decade, researchers have identified and measured various forms of endogenous and environmental mtDNA damage and have elucidated mtDNA repair pathways. Interestingly, mitochondria do not appear to contain the full range of DNA repair mechanisms that operate in the nucleus, although mtDNA contains types of damage that are targets of each nuclear DNA repair pathway. The reduced repair capacity may, in part, explain the high mutation frequency of the mitochondrial chromosome. Since mtDNA replication is dependent on transcription, mtDNA damage may alter mitochondrial gene expression at three levels: by causing DNA polymerase γ nucleotide incorporation errors leading to mutations, by interfering with the priming of mtDNA replication by the mitochondrial RNA polymerase, or by inducing transcriptional mutagenesis or premature transcript termination. This review summarizes our current knowledge of mtDNA damage, its repair, and its effects on mtDNA integrity and gene expression. PMID:22728831

Calorie restriction in mice overexpressing UCP3: evidence that prior mitochondrial uncoupling alters response.

PubMed

Estey, Carmen; Seifert, Erin L; Aguer, Céline; Moffat, Cynthia; Harper, Mary-Ellen

2012-05-01

Calorie restriction (CR) without malnutrition is the only intervention to consistently increase lifespan in all species tested, and lower age-related pathologies in mammals including humans. It has been suggested that uncoupling of mitochondrial oxidative phosphorylation, using chemical uncouplers, mimics CR, and that overlapping mechanisms underlie the phenotypic changes induced by uncoupling and CR. We aimed to critically assess this using a unique mouse model of skeletal muscle-targeted UCP3-induced uncoupling (UCP3Tg), and focused our studies mainly on skeletal muscle mitochondria. Compared to ad libitum fed Wt mice, skeletal muscle mitochondria from ad libitum fed UCP3Tg mice showed higher basal uncoupling and lower H(2)O(2) emission, with unchanged maximal oxidative phosphorylation, and mitochondrial content. UCP3Tg CR mice showed some tendency for differential adaptation to CR, with lowered H(+) leak conductance and evidence for higher H(2)O(2) emission from skeletal muscle mitochondria following 2 weeks CR, and failure to lower H(2)O(2) emission after 1 month CR. Differential adaptation was also apparent at the whole body level: while UCP3Tg CR mice lost as much weight as Wt CR mice, the proportion of muscle lost was higher in UCP3Tg mice. However, a striking outcome of our studies was the absence of change with CR in many of the parameters of mitochondrial function and content that we measured in mice of either genotype. Overall, our study raises the question of whether CR can consistently modify skeletal muscle mitochondria; alterations with CR may only be apparent under certain conditions such as during the 2 wk CR intervention in the UCP3Tg mice. Copyright © 2012 Elsevier Inc. All rights reserved.

Calorie restriction in mice overexpressing UCP3: evidence that prior mitochondrial uncoupling alters response

PubMed Central

Estey, Carmen; Seifert, Erin L.; Aguer, Céline; Moffat, Cynthia; Harper, Mary-Ellen

2012-01-01

SUMMARY Calorie restriction (CR) without malnutrition is the only intervention to consistently increase lifespan in all species tested, and lower age-related pathologies in mammals including humans. It has been suggested that uncoupling of mitochondrial oxidative phosphorylation, using chemical uncouplers, mimics CR, and that overlapping mechanisms underlie the phenotypic changes induced by uncoupling and CR. We aimed to critically assess this using a unique mouse model of skeletal muscle-targeted UCP3-induced uncoupling (UCP3Tg), and focused our studies mainly on skeletal muscle mitochondria. Compared to ad libitum fed Wt mice, skeletal muscle mitochondria from ad libitum fed UCP3Tg mice showed higher basal uncoupling and lower H2O2 emission, with unchanged maximal oxidative phosphorylation, and mitochondrial content. UCP3Tg CR mice showed some tendency for differential adaptation to CR, with lowered H+ leak conductance and evidence for higher H2O2 emission from skeletal muscle mitochondria following 2 weeks CR, and failure to lower H2O2 emission after 1 month CR. Differential adaptation was also apparent at the whole body level: while UCP3Tg CR mice lost as much weight as Wt CR mice, the proportion of muscle lost was higher in UCP3Tg mice. However, a striking outcome of our studies was the absence of change with CR in many of the parameters of mitochondrial function and content that we measured in mice of either genotype. Overall, our study raises the question of whether CR can consistently modify skeletal muscle mitochondria; alterations with CR may only be apparent under certain conditions such as during the 2 wk CR intervention in the UCP3Tg mice. PMID:22406134

Gestational diabetes is characterized by reduced mitochondrial protein expression and altered calcium signaling proteins in skeletal muscle.

PubMed

Boyle, Kristen E; Hwang, Hyonson; Janssen, Rachel C; DeVente, James M; Barbour, Linda A; Hernandez, Teri L; Mandarino, Lawrence J; Lappas, Martha; Friedman, Jacob E

2014-01-01

The rising prevalence of gestational diabetes mellitus (GDM) affects up to 18% of pregnant women with immediate and long-term metabolic consequences for both mother and infant. Abnormal glucose uptake and lipid oxidation are hallmark features of GDM prompting us to use an exploratory proteomics approach to investigate the cellular mechanisms underlying differences in skeletal muscle metabolism between obese pregnant women with GDM (OGDM) and obese pregnant women with normal glucose tolerance (ONGT). Functional validation was performed in a second cohort of obese OGDM and ONGT pregnant women. Quantitative proteomic analysis in rectus abdominus skeletal muscle tissue collected at delivery revealed reduced protein content of mitochondrial complex I (C-I) subunits (NDUFS3, NDUFV2) and altered content of proteins involved in calcium homeostasis/signaling (calcineurin A, α1-syntrophin, annexin A4) in OGDM (n = 6) vs. ONGT (n = 6). Follow-up analyses showed reduced enzymatic activity of mitochondrial complexes C-I, C-III, and C-IV (-60-75%) in the OGDM (n = 8) compared with ONGT (n = 10) subjects, though no differences were observed for mitochondrial complex protein content. Upstream regulators of mitochondrial biogenesis and oxidative phosphorylation were not different between groups. However, AMPK phosphorylation was dramatically reduced by 75% in the OGDM women. These data suggest that GDM is associated with reduced skeletal muscle oxidative phosphorylation and disordered calcium homeostasis. These relationships deserve further attention as they may represent novel risk factors for development of GDM and may have implications on the effectiveness of physical activity interventions on both treatment strategies for GDM and for prevention of type 2 diabetes postpartum.

Characterization of mitochondrial ferritin in Drosophila.

PubMed

Missirlis, Fanis; Holmberg, Sara; Georgieva, Teodora; Dunkov, Boris C; Rouault, Tracey A; Law, John H

2006-04-11

Mitochondrial function depends on iron-containing enzymes and proteins, whose maturation requires available iron for biosynthesis of iron-sulfur clusters and heme. Little is known about how mitochondrial iron homeostasis is maintained, although the recent discovery of a mitochondrial ferritin in mammals and plants has uncovered a potential key player in the process. Here, we show that Drosophila melanogaster expresses mitochondrial ferritin from an intron-containing gene. It has high similarity to the mouse and human mitochondrial ferritin sequences and, as in mammals, is expressed mainly in testis. This ferritin contains a putative mitochondrial targeting sequence and an epitope-tagged version localizes to mitochondria in transfected cells. Overexpression of mitochondrial ferritin fails to alter both total-body iron levels and iron that is bound to secretory ferritins. However, the viability of iron-deficient flies is compromised by overexpression of mitochondrial ferritin, suggesting that it may sequester iron at the expense of other important cellular functions. The conservation of mitochondrial ferritin in an insect species underscores the importance of this iron-storage molecule.

Common effects of lithium and valproate on mitochondrial functions: protection against methamphetamine-induced mitochondrial damage.

PubMed

Bachmann, Rosilla F; Wang, Yun; Yuan, Peixiong; Zhou, Rulun; Li, Xiaoxia; Alesci, Salvatore; Du, Jing; Manji, Husseini K

2009-07-01

Accumulating evidence suggests that mitochondrial dysfunction plays a critical role in the progression of a variety of neurodegenerative and psychiatric disorders. Thus, enhancing mitochondrial function could potentially help ameliorate the impairments of neural plasticity and cellular resilience associated with a variety of neuropsychiatric disorders. A series of studies was undertaken to investigate the effects of mood stabilizers on mitochondrial function, and against mitochondrially mediated neurotoxicity. We found that long-term treatment with lithium and valproate (VPA) enhanced cell respiration rate. Furthermore, chronic treatment with lithium or VPA enhanced mitochondrial function as determined by mitochondrial membrane potential, and mitochondrial oxidation in SH-SY5Y cells. In-vivo studies showed that long-term treatment with lithium or VPA protected against methamphetamine (Meth)-induced toxicity at the mitochondrial level. Furthermore, these agents prevented the Meth-induced reduction of mitochondrial cytochrome c, the mitochondrial anti-apoptotic Bcl-2/Bax ratio, and mitochondrial cytochrome oxidase (COX) activity. Oligoarray analysis demonstrated that the gene expression of several proteins related to the apoptotic pathway and mitochondrial functions were altered by Meth, and these changes were attenuated by treatment with lithium or VPA. One of the genes, Bcl-2, is a common target for lithium and VPA. Knock-down of Bcl-2 with specific Bcl-2 siRNA reduced the lithium- and VPA-induced increases in mitochondrial oxidation. These findings illustrate that lithium and VPA enhance mitochondrial function and protect against mitochondrially mediated toxicity. These agents may have potential clinical utility in the treatment of other diseases associated with impaired mitochondrial function, such as neurodegenerative diseases and schizophrenia.

Mitochondrial Aspects of Synaptic Dysfunction in Alzheimer’s Disease

PubMed Central

Cai, Qian; Tammineni, Prasad

2016-01-01

Alzheimer’s disease (AD) is characterized by brain deposition of amyloid plaques and tau neurofibrillary tangles along with steady cognitive decline. Synaptic damage, an early pathological event, correlates strongly with cognitive deficits and memory loss. Mitochondria are essential organelles for synaptic function. Neurons utilize specialized mechanisms to drive mitochondrial trafficking to synapses in which mitochondria buffer Ca2+ and serve as local energy sources by supplying ATP to sustain neurotransmitter release. Mitochondrial abnormalities are one of the earliest and prominent features in AD patient brains. Amyloid-β (Aβ) and tau both trigger mitochondrial alterations. Accumulating evidence suggests that mitochondrial perturbation acts as a key factor that is involved in synaptic failure and degeneration in AD. The importance of mitochondria in supporting synaptic function has made them a promising target of new therapeutic strategy for AD. Here, we review the molecular mechanisms regulating mitochondrial function at synapses, highlight recent findings on the disturbance of mitochondrial dynamics and transport in AD, and discuss how these alterations impact synaptic vesicle release and thus contribute to synaptic pathology associated with AD. PMID:27767992

Altered zinc transport disrupts mitochondrial protein processing/import in fragile X-associated tremor/ataxia syndrome

PubMed Central

Napoli, Eleonora; Ross-Inta, Catherine; Wong, Sarah; Omanska-Klusek, Alicja; Barrow, Cedrick; Iwahashi, Christine; Garcia-Arocena, Dolores; Sakaguchi, Danielle; Berry-Kravis, Elizabeth; Hagerman, Randi; Hagerman, Paul J.; Giulivi, Cecilia

2011-01-01

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects individuals who are carriers of small CGG premutation expansions in the fragile X mental retardation 1 (FMR1) gene. Mitochondrial dysfunction was observed as an incipient pathological process occurring in individuals who do not display overt features of FXTAS ( 1). Fibroblasts from premutation carriers had lower oxidative phosphorylation capacity (35% of controls) and Complex IV activity (45%), and higher precursor-to-mature ratios (P:M) of nDNA-encoded mitochondrial proteins (3.1-fold). However, fibroblasts from carriers with FXTAS symptoms presented higher FMR1 mRNA expression (3-fold) and lower Complex V (38%) and aconitase activities (43%). Higher P:M of ATPase β-subunit (ATPB) and frataxin were also observed in cortex from patients that died with FXTAS symptoms. Biochemical findings observed in FXTAS cells (lower mature frataxin, lower Complex IV and aconitase activities) along with common phenotypic traits shared by Friedreich's ataxia and FXTAS carriers (e.g. gait ataxia, loss of coordination) are consistent with a defective iron homeostasis in both diseases. Higher P:M, and lower ZnT6 and mature frataxin protein expression suggested defective zinc and iron metabolism arising from altered ZnT protein expression, which in turn impairs the activity of mitochondrial Zn-dependent proteases, critical for the import and processing of cytosolic precursors, such as frataxin. In support of this hypothesis, Zn-treated fibroblasts showed a significant recovery of ATPB P:M, ATPase activity and doubling time, whereas Zn and desferrioxamine extended these recoveries and rescued Complex IV activity. PMID:21558427

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.

Alterations of mitochondrial biogenesis in chronic lymphocytic leukemia cells with loss of p53

PubMed Central

Ogasawara, Marcia A.; Liu, Jinyun; Pelicano, Helene; Hammoudi, Naima; Croce, Carlo M.; Keating, Michael J.; Huang, Peng

2016-01-01

Deletion of chromosome 17p with a loss of p53 is an unfavorable cytogenetic change in chronic lymphocytic leukemia (CLL) with poor clinical outcome. Since p53 affects mitochondrial function and integrity, we examined possible mitochondrial changes in CLL mice with TCL1-Tg/p53−/− and TCL1-Tg/p53+/+ genotypes and in primary leukemia cells from CLL patients with or without 17p-deletion. Although the expression of mitochondrial COX1, ND2, and ND6 decreased in p53−/−CLL cells, there was an increase in mitochondrial biogenesis as evidenced by higher mitochondrial mass and mtDNA copy number associated with an elevated expression of TFAM and PGC-1α. Surprisingly, the overall mitochondrial respiratory activity and maximum reserved capacity increased in p53−/− CLL cells. Our study suggests that leukemia cells lacking p53 seem able to maintain respiratory function by compensatory increase in mitochondrial biogenesis. PMID:27650502

Chlorella diet alters mitochondrial cardiolipin contents differentially in organs of Danio rerio analyzed by a lipidomics approach

PubMed Central

Chao, Yu-Jen; Wu, Wen-Hsin; Balazova, Maria; Wu, Ting-Yuan; Lin, Jamie; Liu, Yi-Wen

2018-01-01

The zebrafish (Danio rerio) is an important and widely used vertebrate model organism for the study of human diseases which include disorders caused by dysfunctional mitochondria. Mitochondria play an essential role in both energy metabolism and apoptosis, which are mediated through a mitochondrial phospholipid cardiolipin (CL). In order to examine the cardiolipin profile in the zebrafish model, we developed a CL analysis platform by using liquid chromatography-mass spectrometry (LC-MS). Meanwhile, we tested whether chlorella diet would alter the CL profile in the larval fish, and in various organs of the adult fish. The results showed that chlorella diet increased the chain length of CL in larval fish. In the adult zebrafish, the distribution patterns of CL species were similar between the adult brain and eye tissues, and between the heart and muscles. Interestingly, monolyso-cardiolipin (MLCL) was not detected in brain and eyes but found in other examined tissues, indicating a different remodeling mechanism to maintain the CL integrity. While the adult zebrafish were fed with chlorella for four weeks, the CL distribution showed an increase of the species of saturated acyl chains in the brain and eyes, but a decrease in the other organs. Moreover, chlorella diet led to a decrease of MLCL percentage in organs except the non-MLCL-containing brain and eyes. The CL analysis in the zebrafish provides an important tool for studying the mechanism of mitochondria diseases, and may also be useful for testing medical regimens targeting against the Barth Syndrome. PMID:29494608

Mutations in glycyl-tRNA synthetase impair mitochondrial metabolism in neurons.

PubMed

Boczonadi, Veronika; Meyer, Kathrin; Gonczarowska-Jorge, Humberto; Griffin, Helen; Roos, Andreas; Bartsakoulia, Marina; Bansagi, Boglarka; Ricci, Giulia; Palinkas, Fanni; Zahedi, René P; Bruni, Francesco; Kaspar, Brian; Lochmüller, Hanns; Boycott, Kym M; Müller, Juliane S; Horvath, Rita

2018-06-15

The nuclear-encoded glycyl-tRNA synthetase gene (GARS) is essential for protein translation in both cytoplasm and mitochondria. In contrast, different genes encode the mitochondrial and cytosolic forms of most other tRNA synthetases. Dominant GARS mutations were described in inherited neuropathies, while recessive mutations cause severe childhood-onset disorders affecting skeletal muscle and heart. The downstream events explaining tissue-specific phenotype-genotype relations remained unclear. We investigated the mitochondrial function of GARS in human cell lines and in the GarsC210R mouse model. Human-induced neuronal progenitor cells (iNPCs) carrying dominant and recessive GARS mutations showed alterations of mitochondrial proteins, which were more prominent in iNPCs with dominant, neuropathy-causing mutations. Although comparative proteomic analysis of iNPCs showed significant changes in mitochondrial respiratory chain complex subunits, assembly genes, Krebs cycle enzymes and transport proteins in both recessive and dominant mutations, proteins involved in fatty acid oxidation were only altered by recessive mutations causing mitochondrial cardiomyopathy. In contrast, significant alterations of the vesicle-associated membrane protein-associated protein B (VAPB) and its downstream pathways such as mitochondrial calcium uptake and autophagy were detected in dominant GARS mutations. The role of VAPB has been supported by similar results in the GarsC210R mice. Our data suggest that altered mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) may be important disease mechanisms leading to neuropathy in this condition.

Mitochondrial Redox Dysfunction and Environmental Exposures

PubMed Central

Caito, Samuel W.

2015-01-01

Abstract Significance: Mitochondria are structurally and biochemically diverse, even within a single type of cell. Protein complexes localized to the inner mitochondrial membrane synthesize ATP by coupling electron transport and oxidative phosphorylation. The organelles produce reactive oxygen species (ROS) from mitochondrial oxygen and ROS can, in turn, alter the function and expression of proteins used for aerobic respiration by post-translational and transcriptional regulation. Recent Advances: New interest is emerging not only into the roles of mitochondria in disease development and progression but also as a target for environmental toxicants. Critical Issues: Dysregulation of respiration has been linked to cell death and is a major contributor to acute neuronal trauma, peripheral diseases, as well as chronic neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Future Directions: Here, we discuss the mechanisms underlying the sensitivity of the mitochondrial respiratory complexes to redox modulation, as well as examine the effects of environmental contaminants that have well-characterized mitochondrial toxicity. The contaminants discussed in this review are some of the most prevalent and potent environmental contaminants that have been linked to neurological dysfunction, altered cellular respiration, and oxidation. Antioxid. Redox Signal. 23, 578–595. PMID:25826672

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.

Mitochondrial mechanisms of neural cell death and neuroprotective interventions in Parkinson's disease.

PubMed

Fiskum, Gary; Starkov, Anatoly; Polster, Brian M; Chinopoulos, Christos

2003-06-01

Mitochondrial dysfunction, due to either environmental or genetic factors, can result in excessive production of reactive oxygen species, triggering the apoptotic death of dopaminergic cells in Parkinson's disease. Mitochondrial free radical production is promoted by the inhibition of electron transport at any point distal to the sites of superoxide production. Neurotoxins that induce parkinsonian neuropathology, such as MPP(+) and rotenone, stimulate superoxide production at complex I of the electron transport chain and also stimulate free radical production at proximal redox sites including mitochondrial matrix dehydrogenases. The oxidative stress caused by elevated mitochondrial production of reactive oxygen species promotes the expression and (or) intracellular distribution of the proapoptotic protein Bax to the mitochondrial outer membrane. Interactions between Bax and BH3 death domain proteins such as tBid result in Bax membrane integration, oligomerization, and permeabilization of the outer membrane to intermembrane proteins such as cytochrome c. Once released into the cytosol, cytochrome c together with other proteins activates the caspase cascade of protease activities that mediate the biochemical and morphological alterations characteristic of apoptosis. In addition, loss of mitochondrial cytochrome c stimulates mitochondrial free radical production, further promoting cell death pathways. Excessive mitochondrial Ca(2+) accumulation can also release cytochrome c and promote superoxide production through a mechanism distinctly different from that of Bax. Ca(2+) activates a mitochondrial inner membrane permeability transition causing osmotic swelling, rupture of the outer membrane, and complete loss of mitochondrial structural and functional integrity. While amphiphilic cations, such as dibucaine and propranolol, inhibit Bax-mediated cytochrome c release, transient receptor potential channel inhibitors inhibit mitochondrial swelling and cytochrome c release

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.

Modulation of mitochondrial function and morphology by interaction of Omi/HtrA2 with the mitochondrial fusion factor OPA1

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

Kieper, Nicole; Holmstroem, Kira M.; Ciceri, Dalila

2010-04-15

Loss of Omi/HtrA2 function leads to nerve cell loss in mouse models and has been linked to neurodegeneration in Parkinson's and Huntington's disease. Omi/HtrA2 is a serine protease released as a pro-apoptotic factor from the mitochondrial intermembrane space into the cytosol. Under physiological conditions, Omi/HtrA2 is thought to be involved in protection against cellular stress, but the cytological and molecular mechanisms are not clear. Omi/HtrA2 deficiency caused an accumulation of reactive oxygen species and reduced mitochondrial membrane potential. In Omi/HtrA2 knockout mouse embryonic fibroblasts, as well as in Omi/HtrA2 silenced human HeLa cells and Drosophila S2R+ cells, we found elongatedmore » mitochondria by live cell imaging. Electron microscopy confirmed the mitochondrial morphology alterations and showed abnormal cristae structure. Examining the levels of proteins involved in mitochondrial fusion, we found a selective up-regulation of more soluble OPA1 protein. Complementation of knockout cells with wild-type Omi/HtrA2 but not with the protease mutant [S306A]Omi/HtrA2 reversed the mitochondrial elongation phenotype and OPA1 alterations. Finally, co-immunoprecipitation showed direct interaction of Omi/HtrA2 with endogenous OPA1. Thus, we show for the first time a direct effect of loss of Omi/HtrA2 on mitochondrial morphology and demonstrate a novel role of this mitochondrial serine protease in the modulation of OPA1. Our results underscore a critical role of impaired mitochondrial dynamics in neurodegenerative disorders.« less

Copper deficiency alters cell bioenergetics and induces mitochondrial fusion through up-regulation of MFN2 and OPA1 in erythropoietic cells

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

Bustos, Rodrigo I.; Jensen, Erik L.; Ruiz, Lina M.

2013-08-02

Highlights: •In copper deficiency, cell proliferation is not affected. In turn, cell differentiation is impaired. •Enlarged mitochondria are due to up-regulation of MNF2 and OPA1. •Mitochondria turn off respiratory chain and ROS production. •Energy metabolism switch from mitochondria to glycolysis. -- Abstract: Copper is essential in cell physiology, participating in numerous enzyme reactions. In mitochondria, copper is a cofactor for respiratory complex IV, the cytochrome c oxidase. Low copper content is associated with anemia and the appearance of enlarged mitochondria in erythropoietic cells. These findings suggest a connection between copper metabolism and bioenergetics, mitochondrial dynamics and erythropoiesis, which has notmore » been explored so far. Here, we describe that bathocuproine disulfonate-induced copper deficiency does not alter erythropoietic cell proliferation nor induce apoptosis. However it does impair erythroid differentiation, which is associated with a metabolic switch between the two main energy-generating pathways. That is, from mitochondrial function to glycolysis. Switching off mitochondria implies a reduction in oxygen consumption and ROS generation along with an increase in mitochondrial membrane potential. Mitochondrial fusion proteins MFN2 and OPA1 were up-regulated along with the ability of mitochondria to fuse. Morphometric analysis of mitochondria did not show changes in total mitochondrial biomass but rather bigger mitochondria because of increased fusion. Similar results were also obtained with human CD34+, which were induced to differentiate into red blood cells. In all, we have shown that adequate copper levels are important for maintaining proper mitochondrial function and for erythroid differentiation where the energy metabolic switch plus the up-regulation of fusion proteins define an adaptive response to copper deprivation to keep cells alive.« less

Role of the mitochondrial DNA replication machinery in mitochondrial DNA mutagenesis, aging and age-related diseases

PubMed Central

DeBalsi, Karen L.; Hoff, Kirsten E.; Copeland, William C.

2016-01-01

As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined. PMID:27143693

Curcumin prevents mitochondrial dynamics disturbances in early 5/6 nephrectomy: Relation to oxidative stress and mitochondrial bioenergetics.

PubMed

Aparicio-Trejo, Omar Emiliano; Tapia, Edilia; Molina-Jijón, Eduardo; Medina-Campos, Omar Noel; Macías-Ruvalcaba, Norma Angélica; León-Contreras, Juan Carlos; Hernández-Pando, Rogelio; García-Arroyo, Fernando E; Cristóbal, Magdalena; Sánchez-Lozada, Laura Gabriela; Pedraza-Chaverri, José

2017-03-01

Five-sixths nephrectomy (5/6NX) is a widely used model to study the mechanisms leading to renal damage in chronic kidney disease (CKD). However, early alterations on renal function, mitochondrial dynamics, and oxidative stress have not been explored yet. Curcumin is an antioxidant that has shown nephroprotection in 5/6NX-induced renal damage. The aim of this study was to explore the effect of curcumin on early mitochondrial alterations induced by 5/6NX in rats. In isolated mitochondria, 5/6NX-induced hydrogen peroxide production was associated with decreased activity of complexes I and V, decreased activity of antioxidant enzymes, alterations in oxygen consumption and increased MDA-protein adducts. In addition, it was found that 5/6NX shifted mitochondrial dynamics to fusion, which was evidenced by increased optic atrophy 1 and mitofusin 1 (Mfn1) and decreased fission 1 and dynamin-related protein 1 expressions. These data were confirmed by morphological analysis and immunoelectron microscopy of Mfn-1. All the above-described mechanisms were prevented by curcumin. Also, it was found that curcumin prevented renal dysfunction by improving renal blood flow and the total antioxidant capacity induced by 5/6NX. Moreover, in glomeruli and proximal tubules 5/6NX-induced superoxide anion production by uncoupled nitric oxide synthase (NOS) and nicotinamide adenine dinucleotide phosphate oxidase (NOX) dependent way, this latter was associated with increased phosphorylation of serine 304 of p47phox subunit of NOX. In conclusion, this study shows that curcumin pretreatment decreases early 5/6NX-induced altered mitochondrial dynamics, bioenergetics, and oxidative stress, which may be associated with the preservation of renal function. © 2016 BioFactors, 43(2):293-310, 2017. © 2016 International Union of Biochemistry and Molecular Biology.

Mitochondrial Stress Tests Using Seahorse Respirometry on Intact Dictyostelium discoideum Cells.

PubMed

Lay, Sui; Sanislav, Oana; Annesley, Sarah J; Fisher, Paul R

2016-01-01

Mitochondria not only play a critical and central role in providing metabolic energy to the cell but are also integral to the other cellular processes such as modulation of various signaling pathways. These pathways affect many aspects of cell physiology, including cell movement, growth, division, differentiation, and death. Mitochondrial dysfunction which affects mitochondrial bioenergetics and causes oxidative phosphorylation defects can thus lead to altered cellular physiology and manifest in disease. The assessment of the mitochondrial bioenergetics can thus provide valuable insights into the physiological state, and the alterations to the state of the cells. Here, we describe a method to successfully use the Seahorse XF(e)24 Extracellular Flux Analyzer to assess the mitochondrial respirometry of the cellular slime mold Dictyostelium discoideum.

Telling apart Felidae and Ursidae from the distribution of nucleotides in mitochondrial DNA

NASA Astrophysics Data System (ADS)

Rovenchak, Andrij

2018-02-01

Rank-frequency distributions of nucleotide sequences in mitochondrial DNA are defined in a way analogous to the linguistic approach, with the highest-frequent nucleobase serving as a whitespace. For such sequences, entropy and mean length are calculated. These parameters are shown to discriminate the species of the Felidae (cats) and Ursidae (bears) families. From purely numerical values we are able to see in particular that giant pandas are bears while koalas are not. The observed linear relation between the parameters is explained using a simple probabilistic model. The approach based on the non-additive generalization of the Bose distribution is used to analyze the frequency spectra of the nucleotide sequences. In this case, the separation of families is not very sharp. Nevertheless, the distributions for Felidae have on average longer tails comparing to Ursidae.

Assessment of Mitochondrial Dysfunction Arising from Treatment with Hepatotoxicants

PubMed Central

King, Adrienne L.; Bailey, Shannon M.

2010-01-01

Studies demonstrate that mitochondrial dysfunction is a key causative factor in liver disease. Indeed, defects in mitochondrial energy metabolism, disrupted calcium handling, and increased reactive oxygen/nitrogen species production are observed in many metabolic disorders and diseases induced by toxicants. Mitochondria have emerged as a main research focus through work defining new functions of this key organelle in normal cellular physiology and pathophysiology. Specifically, studies show a critical role of mitochondrial reactive oxygen/nitrogen species production in regulating cellular signaling pathways involved in cell survival and death. Given this, along with advances made in proteomics technologies, mitochondria are recognized as top candidates for proteomics analysis. However, assessment of mitochondrial function and it’s proteome following toxicant exposure are not trivial undertakings. In this chapter a technique used to isolate mitochondria from liver tissue is presented along with methods needed to assess mitochondria functionality. The methods described include measurement of mitochondrial respiration, calcium accumulation, and reactive oxygen species production. A presentation of proteomics approaches is also included to allow researchers the basic tools needed to identify alterations in the mitochondrial proteome that contribute to toxicant-mediated diseases. Specifically, methods are presented that demonstrate how thiol labeling reagents in combination with electrophoresis and western blotting can be used to detect oxidant-mediated alterations in mitochondrial protein thiols. A few select pieces data are presented highlighting the power of proteomics to identify mitochondrial targets that contribute to mitochondrial dysfunction and hepatotoxicity in response to specific toxicant exposures and metabolic stressors such as alcohol and environmental tobacco smoke. PMID:23045017

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

A ketogenic amino acid rich diet benefits mitochondrial homeostasis by altering the AKT/4EBP1 and autophagy signaling pathways in the gastrocnemius and soleus.

PubMed

Li, Jinpeng; Kanasaki, Megumi; Xu, Ling; Kitada, Munehiro; Nagao, Kenji; Adachi, Yusuke; Jinzu, Hiroko; Noguchi, Yasushi; Kohno, Miyuki; Kanasaki, Keizo; Koya, Daisuke

2018-07-01

Muscle biology is important topic in diabetes research. We have reported that a diet with ketogenic amino acids rich replacement (KAAR) ameliorated high-fat diet (HFD)-induced hepatosteatosis via activation of the autophagy system. Here, we found that a KAAR ameliorated the mitochondrial morphological alterations and associated mitochondrial dysfunction induced by an HFD through induction of the AKT/4EBP1 and autophagy signaling pathways in both fast and slow muscles. The mice were fed with a standard HFD (30% fat in food) or an HFD with KAAR (HFD KAAR ). In both the gastrocnemius and the soleus, HFD KAAR ameliorated HFD-impaired mitochondrial morphology and mitochondrial function, characterized by decreased mitofusin 2, optic atrophy 1, peroxisome proliferator-activated receptor (PPAR) γ coactivator-1α and PPARα levels and increased dynamin-related protein 1 levels. The decreased levels of phosphorylated AKT and 4EBP1 in the gastrocnemius and soleus of HFD-fed mice were remediated by HFD KAAR . Furthermore, the HFD KAAR ameliorated the HFD-induced autophagy defects in the gastrocnemius and soleus. These findings suggest that KAAR may be a novel strategy to combat obesity-induced mitochondrial dysfunction, likely through induction of the AKT/4EBP1 and autophagy pathways in skeletal muscle. Copyright © 2018 Elsevier B.V. All rights reserved.

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

Impaired in vivo mitochondrial Krebs cycle activity after myocardial infarction assessed using hyperpolarized magnetic resonance spectroscopy.

PubMed

Dodd, Michael S; Atherton, Helen J; Carr, Carolyn A; Stuckey, Daniel J; West, James A; Griffin, Julian L; Radda, George K; Clarke, Kieran; Heather, Lisa C; Tyler, Damian J

2014-11-01

Myocardial infarction (MI) is one of the leading causes of heart failure. An increasing body of evidence links alterations in cardiac metabolism and mitochondrial function with the progression of heart disease. The aim of this work was to, therefore, follow the in vivo mitochondrial metabolic alterations caused by MI, thereby allowing a greater understanding of the interplay between metabolic and functional abnormalities. Using hyperpolarized carbon-13 ((13)C)-magnetic resonance spectroscopy, in vivo alterations in mitochondrial metabolism were assessed for 22 weeks after surgically induced MI with reperfusion in female Wister rats. One week after MI, there were no detectable alterations in in vivo cardiac mitochondrial metabolism over the range of ejection fractions observed (from 28% to 84%). At 6 weeks after MI, in vivo mitochondrial Krebs cycle activity was impaired, with decreased (13)C-label flux into citrate, glutamate, and acetylcarnitine, which correlated with the degree of cardiac dysfunction. These changes were independent of alterations in pyruvate dehydrogenase flux. By 22 weeks, alterations were also seen in pyruvate dehydrogenase flux, which decreased at lower ejection fractions. These results were confirmed using in vitro analysis of enzyme activities and metabolomic profiles of key intermediates. The in vivo decrease in Krebs cycle activity in the 6-week post-MI heart may represent an early maladaptive phase in the metabolic alterations after MI in which reductions in Krebs cycle activity precede a reduction in pyruvate dehydrogenase flux. Changes in mitochondrial metabolism in heart disease are progressive and proportional to the degree of cardiac impairment. © 2014 American Heart Association, Inc.

Impaired In Vivo Mitochondrial Krebs Cycle Activity After Myocardial Infarction Assessed Using Hyperpolarized Magnetic Resonance Spectroscopy

PubMed Central

Carr, Carolyn A.; Stuckey, Daniel J.; West, James A.; Griffin, Julian L.; Radda, George K.; Clarke, Kieran; Heather, Lisa C.; Tyler, Damian J.

2015-01-01

Background Myocardial infarction (MI) is one of the leading causes of heart failure. An increasing body of evidence links alterations in cardiac metabolism and mitochondrial function with the progression of heart disease. The aim of this work was to, therefore, follow the in vivo mitochondrial metabolic alterations caused by MI, thereby allowing a greater understanding of the interplay between metabolic and functional abnormalities. Methods and Results Using hyperpolarized carbon-13 (13C)-magnetic resonance spectroscopy, in vivo alterations in mitochondrial metabolism were assessed for 22 weeks after surgically induced MI with reperfusion in female Wister rats. One week after MI, there were no detectable alterations in in vivo cardiac mitochondrial metabolism over the range of ejection fractions observed (from 28% to 84%). At 6 weeks after MI, in vivo mitochondrial Krebs cycle activity was impaired, with decreased 13C-label flux into citrate, glutamate, and acetylcarnitine, which correlated with the degree of cardiac dysfunction. These changes were independent of alterations in pyruvate dehydrogenase flux. By 22 weeks, alterations were also seen in pyruvate dehydrogenase flux, which decreased at lower ejection fractions. These results were confirmed using in vitro analysis of enzyme activities and metabolomic profiles of key intermediates. Conclusions The in vivo decrease in Krebs cycle activity in the 6-week post-MI heart may represent an early maladaptive phase in the metabolic alterations after MI in which reductions in Krebs cycle activity precede a reduction in pyruvate dehydrogenase flux. Changes in mitochondrial metabolism in heart disease are progressive and proportional to the degree of cardiac impairment. PMID:25201905

The mitochondrial-targeted antioxidant, MitoQ, increases liver mitochondrial cardiolipin content in obesogenic diet-fed rats.

PubMed

Fouret, Gilles; Tolika, Evanthia; Lecomte, Jérôme; Bonafos, Béatrice; Aoun, Manar; Murphy, Michael P; Ferreri, Carla; Chatgilialoglu, Chryssostomos; Dubreucq, Eric; Coudray, Charles; Feillet-Coudray, Christine

2015-10-01

Cardiolipin (CL), a unique mitochondrial phospholipid, plays a key role in several processes of mitochondrial bioenergetics as well as in mitochondrial membrane stability and dynamics. The present study was designed to determine the effect of MitoQ, a mitochondrial-targeted antioxidant, on the content of liver mitochondrial membrane phospholipids, in particular CL, and its fatty acid composition in obesogenic diet-fed rats. To do this, twenty-four 6week old male Sprague Dawley rats were randomized into three groups of 8 animals and fed for 8weeks with either a control diet, a high fat diet (HF), or a HF diet with MitoQ (HF+MitoQ). Phospholipid classes and fatty acid composition were assayed by chromatographic methods in liver and liver mitochondria. Mitochondrial bioenergetic function was also evaluated. While MitoQ had no or slight effects on total liver fatty acid composition and phospholipid classes and their fatty acid composition, it had major effects on liver mitochondrial phospholipids and mitochondrial function. Indeed, MitoQ both increased CL synthase gene expression and CL content of liver mitochondria and increased 18:2n-6 (linoleic acid) content of mitochondrial phospholipids by comparison to the HF diet. Moreover, mitochondrial CL content was positively correlated to mitochondrial membrane fluidity, membrane potential and respiration, as well as to ATP synthase activity, while it was negatively correlated to mitochondrial ROS production. These findings suggest that MitoQ may decrease pathogenic alterations to CL content and profiles, thereby preserving mitochondrial function and attenuating the development of some of the features of metabolic syndrome in obesogenic diet-fed rats. Copyright © 2015 Elsevier B.V. All rights reserved.

MitoQ improves mitochondrial dysfunction in heart failure induced by pressure overload.

PubMed

Ribeiro Junior, Rogério Faustino; Dabkowski, Erinne Rose; Shekar, Kadambari Chandra; O Connell, Kelly A; Hecker, Peter A; Murphy, Michael P

2018-03-01

Heart failure remains a major public-health problem with an increase in the number of patients worsening from this disease. Despite current medical therapy, the condition still has a poor prognosis. Heart failure is complex but mitochondrial dysfunction seems to be an important target to improve cardiac function directly. Our goal was to analyze the effects of MitoQ (100 µM in drinking water) on the development and progression of heart failure induced by pressure overload after 14 weeks. The main findings are that pressure overload-induced heart failure in rats decreased cardiac function in vivo that was not altered by MitoQ. However, we observed a reduction in right ventricular hypertrophy and lung congestion in heart failure animals treated with MitoQ. Heart failure also decreased total mitochondrial protein content, mitochondrial membrane potential in the intermyofibrillar mitochondria. MitoQ restored membrane potential in IFM but did not restore mitochondrial protein content. These alterations are associated with the impairment of basal and stimulated mitochondrial respiration in IFM and SSM induced by heart failure. Moreover, MitoQ restored mitochondrial respiration in heart failure induced by pressure overload. We also detected higher levels of hydrogen peroxide production in heart failure and MitoQ restored the increase in ROS production. MitoQ was also able to improve mitochondrial calcium retention capacity, mainly in the SSM whereas in the IFM we observed a small alteration. In summary, MitoQ improves mitochondrial dysfunction in heart failure induced by pressure overload, by decreasing hydrogen peroxide formation, improving mitochondrial respiration and improving mPTP opening. Published by Elsevier Inc.

Pharmacological modulation of mitochondrial calcium homeostasis.

PubMed

Arduino, Daniela M; Perocchi, Fabiana

2018-01-10

Mitochondria are pivotal organelles in calcium (Ca 2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca 2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca 2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca 2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca 2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca 2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems-level pharmacological targeting of mitochondrial Ca 2+ homeostasis. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

The expanding phenotype of mitochondrial myopathy.

PubMed

DiMauro, Salvatore; Gurgel-Giannetti, Juliana

2005-10-01

Our understanding of mitochondrial diseases (defined restrictively as defects in the mitochondrial respiratory chain) continues to progress apace. In this review we provide an update of information regarding disorders that predominantly or exclusively affect skeletal muscle. Most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency, and mutations in genes that control mitochondrial DNA (mtDNA) abundance and structure such as POLG and TK2. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with altered lipid composition of the inner mitochondrial membrane, but a putative secondary impairment of the respiratory chain remains to be documented. Concerning the 'other genome', the role played by mutations in protein encoding genes of mtDNA in causing isolated myopathies has been confirmed. It has also been confirmed that mutations in tRNA genes of mtDNA can cause predominantly myopathic syndromes and - contrary to conventional wisdom - these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, myalgia, cramps, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

Metabolic Syndrome and Antipsychotics: The Role of Mitochondrial Fission/Fusion Imbalance.

PubMed

Del Campo, Andrea; Bustos, Catalina; Mascayano, Carolina; Acuña-Castillo, Claudio; Troncoso, Rodrigo; Rojo, Leonel E

2018-01-01

Second-generation antipsychotics (SGAs) are known to increase cardiovascular risk through several physiological mechanisms, including insulin resistance, hepatic steatosis, hyperphagia, and accelerated weight gain. There are limited prophylactic interventions to prevent these side effects of SGAs, in part because the molecular mechanisms underlying SGAs toxicity are not yet completely elucidated. In this perspective article, we introduce an innovative approach to study the metabolic side effects of antipsychotics through the alterations of the mitochondrial dynamics, which leads to an imbalance in mitochondrial fusion/fission ratio and to an inefficient mitochondrial phenotype of muscle cells. We believe that this approach may offer a valuable path to explain SGAs-induced alterations in metabolic homeostasis.

Alterations in Energy/Redox Metabolism Induced by Mitochondrial and Environmental Toxins: A Specific Role for Glucose-6-Phosphate-Dehydrogenase and the Pentose Phosphate Pathway in Paraquat Toxicity

PubMed Central

2015-01-01

Parkinson’s disease (PD) is a multifactorial disorder with a complex etiology including genetic risk factors, environmental exposures, and aging. While energy failure and oxidative stress have largely been associated with the loss of dopaminergic cells in PD and the toxicity induced by mitochondrial/environmental toxins, very little is known regarding the alterations in energy metabolism associated with mitochondrial dysfunction and their causative role in cell death progression. In this study, we investigated the alterations in the energy/redox-metabolome in dopaminergic cells exposed to environmental/mitochondrial toxins (paraquat, rotenone, 1-methyl-4-phenylpyridinium [MPP+], and 6-hydroxydopamine [6-OHDA]) in order to identify common and/or different mechanisms of toxicity. A combined metabolomics approach using nuclear magnetic resonance (NMR) and direct-infusion electrospray ionization mass spectrometry (DI-ESI-MS) was used to identify unique metabolic profile changes in response to these neurotoxins. Paraquat exposure induced the most profound alterations in the pentose phosphate pathway (PPP) metabolome. 13C-glucose flux analysis corroborated that PPP metabolites such as glucose-6-phosphate, fructose-6-phosphate, glucono-1,5-lactone, and erythrose-4-phosphate were increased by paraquat treatment, which was paralleled by inhibition of glycolysis and the TCA cycle. Proteomic analysis also found an increase in the expression of glucose-6-phosphate dehydrogenase (G6PD), which supplies reducing equivalents by regenerating nicotinamide adenine dinucleotide phosphate (NADPH) levels. Overexpression of G6PD selectively increased paraquat toxicity, while its inhibition with 6-aminonicotinamide inhibited paraquat-induced oxidative stress and cell death. These results suggest that paraquat “hijacks” the PPP to increase NADPH reducing equivalents and stimulate paraquat redox cycling, oxidative stress, and cell death. Our study clearly demonstrates that alterations

Detection of mitochondrial DNA mutations in primary breast cancer and fine-needle aspirates.

PubMed

Parrella, P; Xiao, Y; Fliss, M; Sanchez-Cespedes, M; Mazzarelli, P; Rinaldi, M; Nicol, T; Gabrielson, E; Cuomo, C; Cohen, D; Pandit, S; Spencer, M; Rabitti, C; Fazio, V M; Sidransky, D

2001-10-15

To determine the frequency and distribution of mitochondrial DNA mutations in breast cancer, 18 primary breast tumors were analyzed by direct sequencing. Twelve somatic mutations not present in matched lymphocytes and normal breast tissues were detected in 11 of the tumors screened (61%). Of these mutations, five (42%) were deletions or insertions in a homopolymeric C-stretch between nucleotides 303-315 (D310) within the D-loop. The remaining seven mutations (58%) were single-base substitutions in the coding (ND1, ND4, ND5, and cytochrome b genes) or noncoding regions (D-loop) of the mitochondrial genome. In three cases (25%), the mutations detected in coding regions led to amino acid substitutions in the protein sequence. We then screened an additional 46 primary breast tumors with a rapid PCR-based assay to identify poly-C alterations in D310, and we found seven more cancers with alterations. Using D310 mutations as clonal marker, we detected identical changes in five of five matched fine-needle aspirates and in four of four metastases-positive lymph nodes. The high frequency of D310 alterations in primary breast cancer combined with the high sensitivity of the PCR-based assays provides a new molecular tool for cancer detection.

Chicken or the egg: Warburg effect and mitochondrial dysfunction

PubMed Central

Senyilmaz, Deniz

2015-01-01

Compared with normal cells, cancer cells show alterations in many cellular processes, including energy metabolism. Studies on cancer metabolism started with Otto Warburg's observation at the beginning of the last century. According to Warburg, cancer cells rely on glycolysis more than mitochondrial respiration for energy production. Considering that glycolysis yields much less energy compared with mitochondrial respiration, Warburg hypothesized that mitochondria must be dysfunctional and this is the initiating factor for cancer formation. However, this hypothesis did not convince every scientist in the field. Some believed the opposite: the reduction in mitochondrial activity is a result of increased glycolysis. This discrepancy of opinions is ongoing. In this review, we will discuss the alterations in glycolysis, pyruvate metabolism, and the Krebs cycle in cancer cells and focus on cause and consequence. PMID:26097714

Cerebral Mitochondrial Microangiopathy Leads to Leukoencephalopathy in Mitochondrial Neurogastrointestinal Encephalopathy.

PubMed

Gramegna, L L; Pisano, A; Testa, C; Manners, D N; D'Angelo, R; Boschetti, E; Giancola, F; Pironi, L; Caporali, L; Capristo, M; Valentino, M L; Plazzi, G; Casali, C; Dotti, M T; Cenacchi, G; Hirano, M; Giordano, C; Parchi, P; Rinaldi, R; De Giorgio, R; Lodi, R; Carelli, V; Tonon, C

2018-01-18

Mitochondrial neurogastrointestinal encephalopathy is a rare disorder due to recessive mutations in the thymidine phosphorylase gene, encoding thymidine phosphorylase protein required for mitochondrial DNA replication. Clinical manifestations include gastrointestinal dysmotility and diffuse asymptomatic leukoencephalopathy. This study aimed to elucidate the mechanisms underlying brain leukoencephalopathy in patients with mitochondrial neurogastrointestinal encephalopathy by correlating multimodal neuroradiologic features to postmortem pathology. Seven patients underwent brain MR imaging, including single-voxel proton MR spectroscopy and diffusion imaging. Absolute concentrations of metabolites calculated by acquiring unsuppressed water spectra at multiple TEs, along with diffusion metrics based on the tensor model, were compared with those of healthy controls using unpaired t tests in multiple white matters regions. Brain postmortem histologic, immunohistochemical, and molecular analyses were performed in 1 patient. All patients showed bilateral and nearly symmetric cerebral white matter hyperintensities on T2-weighted images, extending to the cerebellar white matter and brain stem in 4. White matter, N -acetylaspartate, creatine, and choline concentrations were significantly reduced compared with those in controls, with a prominent increase in the radial water diffusivity component. At postmortem examination, severe fibrosis of brain vessel smooth muscle was evident, along with mitochondrial DNA replication depletion in brain and vascular smooth-muscle and endothelial cells, without neuronal loss, myelin damage, or gliosis. Prominent periependymal cytochrome C oxidase deficiency was also observed. Vascular functional and histologic alterations account for leukoencephalopathy in mitochondrial neurogastrointestinal encephalopathy. Thymidine toxicity and mitochondrial DNA replication depletion may induce microangiopathy and blood-brain-barrier dysfunction, leading to

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.

Insulin Resistance and Mitochondrial Dysfunction.

PubMed

Gonzalez-Franquesa, Alba; Patti, Mary-Elizabeth

2017-01-01

Insulin resistance precedes and predicts the onset of type 2 diabetes (T2D) in susceptible humans, underscoring its important role in the complex pathogenesis of this disease. Insulin resistance contributes to multiple tissue defects characteristic of T2D, including reduced insulin-stimulated glucose uptake in insulin-sensitive tissues, increased hepatic glucose production, increased lipolysis in adipose tissue, and altered insulin secretion. Studies of individuals with insulin resistance, both with established T2D and high-risk individuals, have consistently demonstrated a diverse array of defects in mitochondrial function (i.e., bioenergetics, biogenesis and dynamics). However, it remains uncertain whether mitochondrial dysfunction is primary (critical initiating defect) or secondary to the subtle derangements in glucose metabolism, insulin resistance, and defective insulin secretion present early in the course of disease development. In this chapter, we will present the evidence linking mitochondrial dysfunction and insulin resistance, and review the potential for mitochondrial targets as a therapeutic approach for T2D.

Bitter taste receptor agonists alter mitochondrial function and induce autophagy in airway smooth muscle cells.

PubMed

Pan, Shi; Sharma, Pawan; Shah, Sushrut D; Deshpande, Deepak A

2017-07-01

Airway remodeling, including increased airway smooth muscle (ASM) mass, is a hallmark feature of asthma and COPD. We previously identified the expression of bitter taste receptors (TAS2Rs) on human ASM cells and demonstrated that known TAS2R agonists could promote ASM relaxation and bronchodilation and inhibit mitogen-induced ASM growth. In this study, we explored cellular mechanisms mediating the antimitogenic effect of TAS2R agonists on human ASM cells. Pretreatment of ASM cells with TAS2R agonists chloroquine and quinine resulted in inhibition of cell survival, which was largely reversed by bafilomycin A1, an autophagy inhibitor. Transmission electron microscope studies demonstrated the presence of double-membrane autophagosomes and deformed mitochondria. In ASM cells, TAS2R agonists decreased mitochondrial membrane potential and increased mitochondrial ROS and mitochondrial fragmentation. Inhibiting dynamin-like protein 1 (DLP1) reversed TAS2R agonist-induced mitochondrial membrane potential change and attenuated mitochondrial fragmentation and cell death. Furthermore, the expression of mitochondrial protein BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (Bnip3) and mitochondrial localization of DLP1 were significantly upregulated by TAS2R agonists. More importantly, inhibiting Bnip3 mitochondrial localization by dominant-negative Bnip3 significantly attenuated cell death induced by TAS2R agonist. Collectively the TAS2R agonists chloroquine and quinine modulate mitochondrial structure and function, resulting in ASM cell death. Furthermore, Bnip3 plays a central role in TAS2R agonist-induced ASM functional changes via a mitochondrial pathway. These findings further establish the cellular mechanisms of antimitogenic effects of TAS2R agonists and identify a novel class of receptors and pathways that can be targeted to mitigate airway remodeling as well as bronchoconstriction in obstructive airway diseases. Copyright © 2017 the American Physiological

Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales.

PubMed

Baker, C S; Palumbi, S R; Lambertsen, R H; Weinrich, M T; Calambokidis, J; O'Brien, S J

1990-03-15

Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations.

Mitochondrial O-GlcNAc Transferase (mOGT) Regulates Mitochondrial Structure, Function, and Survival in HeLa Cells*

PubMed Central

Sacoman, Juliana L.; Dagda, Raul Y.; Burnham-Marusich, Amanda R.; Dagda, Ruben K.; Berninsone, Patricia M.

2017-01-01

O-Linked N-acetylglucosamine transferase (OGT) catalyzes O-GlcNAcylation of target proteins and regulates numerous biological processes. OGT is encoded by a single gene that yields nucleocytosolic and mitochondrial isoforms. To date, the role of the mitochondrial isoform of OGT (mOGT) remains largely unknown. Using high throughput proteomics, we identified 84 candidate mitochondrial glycoproteins, of which 44 are novel. Notably, two of the candidate glycoproteins identified (cytochrome oxidase 2 (COX2) and NADH:ubiquinone oxidoreductase core subunit 4 (MT-ND4)) are encoded by mitochondrial DNA. Using siRNA in HeLa cells, we found that reducing endogenous mOGT expression leads to alterations in mitochondrial structure and function, including Drp1-dependent mitochondrial fragmentation, reduction in mitochondrial membrane potential, and a significant loss of mitochondrial content in the absence of mitochondrial ROS. These defects are associated with a compensatory increase in oxidative phosphorylation per mitochondrion. mOGT is also critical for cell survival; siRNA-mediated knockdown of endogenous mOGT protected cells against toxicity mediated by rotenone, a complex I inhibitor. Conversely, reduced expression of both nucleocytoplasmic (ncOGT) and mitochondrial (mOGT) OGT isoforms is associated with increased mitochondrial respiration and elevated glycolysis, suggesting that ncOGT is a negative regulator of cellular bioenergetics. Last, we determined that mOGT is probably involved in the glycosylation of a restricted set of mitochondrial targets. We identified four proteins implicated in mitochondrial biogenesis and metabolism regulation as candidate substrates of mOGT, including leucine-rich PPR-containing protein and mitochondrial aconitate hydratase. Our findings suggest that mOGT is catalytically active in vivo and supports mitochondrial structure, health, and survival, whereas ncOGT predominantly regulates cellular bioenergetics. PMID:28100784

Models of plasma membrane organization can be applied to mitochondrial membranes to target human health and disease with polyunsaturated fatty acids.

PubMed

Raza Shaikh, Saame; Brown, David A

2013-01-01

Bioactive n-3 polyunsaturated fatty acids (PUFA), abundant in fish oil, have potential for treating symptoms associated with inflammatory and metabolic disorders; therefore, it is essential to determine their fundamental molecular mechanisms. Recently, several labs have demonstrated the n-3 PUFA docosahexaenoic acid (DHA) exerts anti-inflammatory effects by targeting the molecular organization of plasma membrane microdomains. Here we briefly review the evidence that DHA reorganizes the spatial distribution of microdomains in several model systems. We then emphasize how models on DHA and plasma membrane microdomains can be applied to mitochondrial membranes. We discuss the role of DHA acyl chains in regulating mitochondrial lipid-protein clustering, and how these changes alter several aspects of mitochondrial function. In particular, we summarize effects of DHA on mitochondrial respiration, electron leak, permeability transition, and mitochondrial calcium handling. Finally, we conclude by postulating future experiments that will augment our understanding of DHA-dependent membrane organization in health and disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mitochondrial proteome remodelling in pressure overload-induced heart failure: the role of mitochondrial oxidative stress

PubMed Central

Dai, Dao-Fu; Hsieh, Edward J.; Liu, Yonggang; Chen, Tony; Beyer, Richard P.; Chin, Michael T.; MacCoss, Michael J.; Rabinovitch, Peter S.

2012-01-01

Aims We investigate the role of mitochondrial oxidative stress in mitochondrial proteome remodelling using mouse models of heart failure induced by pressure overload. Methods and results We demonstrate that mice overexpressing catalase targeted to mitochondria (mCAT) attenuate pressure overload-induced heart failure. An improved method of label-free unbiased analysis of the mitochondrial proteome was applied to the mouse model of heart failure induced by transverse aortic constriction (TAC). A total of 425 mitochondrial proteins were compared between wild-type and mCAT mice receiving TAC or sham surgery. The changes in the mitochondrial proteome in heart failure included decreased abundance of proteins involved in fatty acid metabolism, an increased abundance of proteins in glycolysis, apoptosis, mitochondrial unfolded protein response and proteolysis, transcription and translational control, and developmental processes as well as responses to stimuli. Overexpression of mCAT better preserved proteins involved in fatty acid metabolism and attenuated the increases in apoptotic and proteolytic enzymes. Interestingly, gene ontology analysis also showed that monosaccharide metabolic processes and protein folding/proteolysis were only overrepresented in mCAT but not in wild-type mice in response to TAC. Conclusion This is the first study to demonstrate that scavenging mitochondrial reactive oxygen species (ROS) by mCAT not only attenuates most of the mitochondrial proteome changes in heart failure, but also induces a subset of unique alterations. These changes represent processes that are adaptive to the increased work and metabolic requirements of pressure overload, but which are normally inhibited by overproduction of mitochondrial ROS. PMID:22012956

Yeast mitochondrial glutathione is an essential antioxidant with mitochondrial thioredoxin providing a back-up system

PubMed Central

Gostimskaya, Irina; Grant, Chris M.

2016-01-01

Glutathione is an abundant, low-molecular-weight tripeptide whose biological importance is dependent upon its redox-active free sulphydryl moiety. Its role as the main determinant of thiol-redox control has been challenged such that it has been proposed to play a crucial role in iron–sulphur clusters maturation, and only a minor role in thiol redox regulation, predominantly as a back-up system for the cytoplasmic thioredoxin system. Here, we have tested the importance of mitochondrial glutathione in thiol-redox regulation. Glutathione reductase (Glr1) is an oxidoreductase which converts oxidized glutathione to its reduced form. Yeast Glr1 localizes to both the cytosol and mitochondria and we have used a Glr1M1L mutant that is constitutively localized to the cytosol to test the requirement for mitochondrial Glr1. We show that the loss of mitochondrial Glr1 specifically accounts for oxidant sensitivity of a glr1 mutant. Loss of mitochondrial Glr1 does not influence iron–sulphur cluster maturation and we have used targeted roGFP2 fluorescent probes to show that oxidant sensitivity is linked to an altered redox environment. Our data indicate mitochondrial glutathione is crucial for mitochondrial thiol-redox regulation, and the mitochondrial thioredoxin system provides a back-up system, but cannot bear the redox load of the mitochondria on its own. PMID:26898146

Mitochondrial Targeted Coenzyme Q, Superoxide, and Fuel Selectivity in Endothelial Cells

PubMed Central

Fink, Brian D.; O'Malley, Yunxia; Dake, Brian L.; Ross, Nicolette C.; Prisinzano, Thomas E.; Sivitz, William I.

2009-01-01

Background Previously, we reported that the “antioxidant” compound “mitoQ” (mitochondrial-targeted ubiquinol/ubiquinone) actually increased superoxide production by bovine aortic endothelial (BAE) cell mitochondria incubated with complex I but not complex II substrates. Methods and Results To further define the site of action of the targeted coenzyme Q compound, we extended these studies to include different substrate and inhibitor conditions. In addition, we assessed the effects of mitoquinone on mitochondrial respiration, measured respiration and mitochondrial membrane potential in intact cells, and tested the intriguing hypothesis that mitoquinone might impart fuel selectivity in intact BAE cells. In mitochondria respiring on differing concentrations of complex I substrates, mitoquinone and rotenone had interactive effects on ROS consistent with redox cycling at multiple sites within complex I. Mitoquinone increased respiration in isolated mitochondria respiring on complex I but not complex II substrates. Mitoquinone also increased oxygen consumption by intact BAE cells. Moreover, when added to intact cells at 50 to 1000 nM, mitoquinone increased glucose oxidation and reduced fat oxidation, at doses that did not alter membrane potential or induce cell toxicity. Although high dose mitoquinone reduced mitochondrial membrane potential, the positively charged mitochondrial-targeted cation, decyltriphenylphosphonium (mitoquinone without the coenzyme Q moiety), decreased membrane potential more than mitoquinone, but did not alter fuel selectivity. Therefore, non-specific effects of the positive charge were not responsible and the quinone moiety is required for altered nutrient selectivity. Conclusions In summary, the interactive effects of mitoquinone and rotenone are consistent with redox cycling at more than one site within complex I. In addition, mitoquinone has substrate dependent effects on mitochondrial respiration, increases repiration by intact cells

Mitochondrial targeted coenzyme Q, superoxide, and fuel selectivity in endothelial cells.

PubMed

Fink, Brian D; O'Malley, Yunxia; Dake, Brian L; Ross, Nicolette C; Prisinzano, Thomas E; Sivitz, William I

2009-01-01

Previously, we reported that the "antioxidant" compound "mitoQ" (mitochondrial-targeted ubiquinol/ubiquinone) actually increased superoxide production by bovine aortic endothelial (BAE) cell mitochondria incubated with complex I but not complex II substrates. To further define the site of action of the targeted coenzyme Q compound, we extended these studies to include different substrate and inhibitor conditions. In addition, we assessed the effects of mitoquinone on mitochondrial respiration, measured respiration and mitochondrial membrane potential in intact cells, and tested the intriguing hypothesis that mitoquinone might impart fuel selectivity in intact BAE cells. In mitochondria respiring on differing concentrations of complex I substrates, mitoquinone and rotenone had interactive effects on ROS consistent with redox cycling at multiple sites within complex I. Mitoquinone increased respiration in isolated mitochondria respiring on complex I but not complex II substrates. Mitoquinone also increased oxygen consumption by intact BAE cells. Moreover, when added to intact cells at 50 to 1000 nM, mitoquinone increased glucose oxidation and reduced fat oxidation, at doses that did not alter membrane potential or induce cell toxicity. Although high dose mitoquinone reduced mitochondrial membrane potential, the positively charged mitochondrial-targeted cation, decyltriphenylphosphonium (mitoquinone without the coenzyme Q moiety), decreased membrane potential more than mitoquinone, but did not alter fuel selectivity. Therefore, non-specific effects of the positive charge were not responsible and the quinone moiety is required for altered nutrient selectivity. In summary, the interactive effects of mitoquinone and rotenone are consistent with redox cycling at more than one site within complex I. In addition, mitoquinone has substrate dependent effects on mitochondrial respiration, increases repiration by intact cells, and alters fuel selectivity favoring glucose over

Mitofusin2 mutations disrupt axonal mitochondrial positioning and promote axon degeneration

PubMed Central

Misko, Albert; Sasaki, Yo; Tuck, Elizabeth; Milbrandt, Jeffrey; Baloh, Robert H.

2012-01-01

Summary Alterations in mitochondrial dynamics (fission, fusion and movement) are implicated in many neurodegenerative diseases, from rare genetic disorders such as Charcot-Marie-Tooth disease, to common conditions including Alzheimer’s disease. However, the relationship between altered mitochondrial dynamics and neurodegeneration is incompletely understood. Here we show that disease associated MFN2 proteins suppressed both mitochondrial fusion and transport, and produced classic features of segmental axonal degeneration without cell body death, including neurofilament filled swellings, loss of calcium homeostasis, and accumulation of reactive oxygen species. By contrast, depletion of Opa1 suppressed mitochondrial fusion while sparing transport, and did not induce axonal degeneration. Axon degeneration induced by mutant MFN2 proteins correlated with the disruption of the proper mitochondrial positioning within axons, rather than loss of overall mitochondrial movement, or global mitochondrial dysfunction. We also found that augmenting expression of MFN1 rescued the axonal degeneration caused by MFN2 mutants, suggesting a possible therapeutic strategy for Charcot-Marie-Tooth disease. These experiments provide evidence that the ability of mitochondria to sense energy requirements and localize properly within axons is key to maintaining axonal integrity, and may be a common pathway by which disruptions in axonal transport contribute to neurodegeneration. PMID:22442078

Autophagy and mitochondrial alterations in human retinal pigment epithelial cells induced by ethanol: implications of 4-hydroxy-nonenal.

PubMed

Flores-Bellver, M; Bonet-Ponce, L; Barcia, J M; Garcia-Verdugo, J M; Martinez-Gil, N; Saez-Atienzar, S; Sancho-Pelluz, J; Jordan, J; Galindo, M F; Romero, F J

2014-07-17

Retinal pigment epithelium has a crucial role in the physiology and pathophysiology of the retina due to its location and metabolism. Oxidative damage has been demonstrated as a pathogenic mechanism in several retinal diseases, and reactive oxygen species are certainly important by-products of ethanol (EtOH) metabolism. Autophagy has been shown to exert a protective effect in different cellular and animal models. Thus, in our model, EtOH treatment increases autophagy flux, in a concentration-dependent manner. Mitochondrial morphology seems to be clearly altered under EtOH exposure, leading to an apparent increase in mitochondrial fission. An increase in 2',7'-dichlorofluorescein fluorescence and accumulation of lipid peroxidation products, such as 4-hydroxy-nonenal (4-HNE), among others were confirmed. The characterization of these structures confirmed their nature as aggresomes. Hence, autophagy seems to have a cytoprotective role in ARPE-19 cells under EtOH damage, by degrading fragmented mitochondria and 4-HNE aggresomes. Herein, we describe the central implication of autophagy in human retinal pigment epithelial cells upon oxidative stress induced by EtOH, with possible implications for other conditions and diseases.

Mitochondrial dynamics and the cell cycle

USDA-ARS?s Scientific Manuscript database

Nuclear-mitochondrial (NM) communication impacts many aspects of plant development including vigor, sterility and viability. Dynamic changes in mitochondrial number, shape, size, and cellular location takes place during the cell cycle possibly impacting the process itself and leading to distribution...

A cell death assay for assessing the mitochondrial targeting of proteins.

PubMed

Camara Teixeira, Daniel; Cordonier, Elizabeth L; Wijeratne, Subhashinee S K; Huebbe, Patricia; Jamin, Augusta; Jarecke, Sarah; Wiebe, Matthew; Zempleni, Janos

2018-06-01

The mitochondrial proteome comprises 1000 to 1500 proteins, in addition to proteins for which the mitochondrial localization is uncertain. About 800 diseases have been linked with mutations in mitochondrial proteins. We devised a cell survival assay for assessing the mitochondrial localization in a high-throughput format. This protocol allows us to assess the mitochondrial localization of proteins and their mutants, and to identify drugs and nutrients that modulate the mitochondrial targeting of proteins. The assay works equally well for proteins directed to the outer mitochondrial membrane, inner mitochondrial membrane mitochondrial and mitochondrial matrix, as demonstrated by assessing the mitochondrial targeting of the following proteins: carnitine palmitoyl transferase 1 (consensus sequence and R123C mutant), acetyl-CoA carboxylase 2, uncoupling protein 1 and holocarboxylase synthetase. Our screen may be useful for linking the mitochondrial proteome with rare diseases and for devising drug- and nutrition-based strategies for altering the mitochondrial targeting of proteins. Copyright © 2018 Elsevier Inc. All rights reserved.

Metabolic Syndrome and Antipsychotics: The Role of Mitochondrial Fission/Fusion Imbalance

PubMed Central

del Campo, Andrea; Bustos, Catalina; Mascayano, Carolina; Acuña-Castillo, Claudio; Troncoso, Rodrigo; Rojo, Leonel E.

2018-01-01

Second-generation antipsychotics (SGAs) are known to increase cardiovascular risk through several physiological mechanisms, including insulin resistance, hepatic steatosis, hyperphagia, and accelerated weight gain. There are limited prophylactic interventions to prevent these side effects of SGAs, in part because the molecular mechanisms underlying SGAs toxicity are not yet completely elucidated. In this perspective article, we introduce an innovative approach to study the metabolic side effects of antipsychotics through the alterations of the mitochondrial dynamics, which leads to an imbalance in mitochondrial fusion/fission ratio and to an inefficient mitochondrial phenotype of muscle cells. We believe that this approach may offer a valuable path to explain SGAs-induced alterations in metabolic homeostasis. PMID:29740394

Tracing glacial refugia of Triturus newts based on mitochondrial DNA phylogeography and species distribution modeling

PubMed Central

2013-01-01

Introduction The major climatic oscillations during the Quaternary Ice Age heavily influenced the distribution of species and left their mark on intraspecific genetic diversity. Past range shifts can be reconstructed with the aid of species distribution modeling and phylogeographical analyses. We test the responses of the different members of the genus Triturus (i.e. the marbled and crested newts) as the climate shifted from the previous glacial period (the Last Glacial Maximum, ~21 Ka) to the current interglacial. Results We present the results of a dense mitochondrial DNA phylogeography (visualizing genetic diversity within and divergence among populations) and species distribution modeling (using two different climate simulations) for the nine Triturus species on composite maps. Conclusions The combined use of species distribution modeling and mitochondrial phylogeography provides insight in the glacial contraction and postglacial expansion of Triturus. The combined use of the two independent techniques yields a more complete understanding of the historical biogeography of Triturus than both approaches would on their own. Triturus newts generally conform to the ‘southern richness and northern purity’ paradigm, but we also find more intricate patterns, such as the absence of genetic variation and suitable area at the Last Glacial Maximum (T. dobrogicus), an ‘extra-Mediterranean’ refugium in the Carpathian Basin (T. cristatus), and areas where species displaced one another postglacially (e.g. T. macedonicus and western T. karelinii). We provide a biogeographical scenario for Triturus, showing the positions of glacial refugia, the regions that were postglacially colonized and the areas where species displaced one another as they shifted their ranges. PMID:23514662

Tracing glacial refugia of Triturus newts based on mitochondrial DNA phylogeography and species distribution modeling.

PubMed

Wielstra, Ben; Crnobrnja-Isailović, Jelka; Litvinchuk, Spartak N; Reijnen, Bastian T; Skidmore, Andrew K; Sotiropoulos, Konstantinos; Toxopeus, Albertus G; Tzankov, Nikolay; Vukov, Tanja; Arntzen, Jan W

2013-03-20

The major climatic oscillations during the Quaternary Ice Age heavily influenced the distribution of species and left their mark on intraspecific genetic diversity. Past range shifts can be reconstructed with the aid of species distribution modeling and phylogeographical analyses. We test the responses of the different members of the genus Triturus (i.e. the marbled and crested newts) as the climate shifted from the previous glacial period (the Last Glacial Maximum, ~21 Ka) to the current interglacial. We present the results of a dense mitochondrial DNA phylogeography (visualizing genetic diversity within and divergence among populations) and species distribution modeling (using two different climate simulations) for the nine Triturus species on composite maps. The combined use of species distribution modeling and mitochondrial phylogeography provides insight in the glacial contraction and postglacial expansion of Triturus. The combined use of the two independent techniques yields a more complete understanding of the historical biogeography of Triturus than both approaches would on their own. Triturus newts generally conform to the 'southern richness and northern purity' paradigm, but we also find more intricate patterns, such as the absence of genetic variation and suitable area at the Last Glacial Maximum (T. dobrogicus), an 'extra-Mediterranean' refugium in the Carpathian Basin (T. cristatus), and areas where species displaced one another postglacially (e.g. T. macedonicus and western T. karelinii). We provide a biogeographical scenario for Triturus, showing the positions of glacial refugia, the regions that were postglacially colonized and the areas where species displaced one another as they shifted their ranges.

RNS60, a charge-stabilized nanostructure saline alters Xenopus Laevis oocyte biophysical membrane properties by enhancing mitochondrial ATP production

PubMed Central

Choi, Soonwook; Yu, Eunah; Kim, Duk-Soo; Sugimori, Mutsuyuki; Llinás, Rodolfo R

2015-01-01

We have examined the effects of RNS60, a 0.9% saline containing charge-stabilized oxygen nanobubble-based structures. RNS60 is generated by subjecting normal saline to Taylor–Couette–Poiseuille (TCP) flow under elevated oxygen pressure. This study, implemented in Xenopus laevis oocytes, addresses both the electrophysiological membrane properties and parallel biological processes in the cytoplasm. Intracellular recordings from defolliculated X. laevis oocytes were implemented in: (1) air oxygenated standard Ringer's solution, (2) RNS60-based Ringer's solution, (3) RNS10.3 (TCP-modified saline without excess oxygen)-based Ringer's, and (4) ONS60 (saline containing high pressure oxygen without TCP modification)-based Ringer's. RNS60-based Ringer's solution induced membrane hyperpolarization from the resting membrane potential. This effect was prevented by: (1) ouabain (a blocker of the sodium/potassium ATPase), (2) rotenone (a mitochondrial electron transfer chain inhibitor preventing usable ATP synthesis), and (3) oligomycin A (an inhibitor of ATP synthase) indicating that RNS60 effects intracellular ATP levels. Increased intracellular ATP levels following RNS60 treatment were directly demonstrated using luciferin/luciferase photon emission. These results indicate that RNS60 alters intrinsic the electrophysiological properties of the X. laevis oocyte membrane by increasing mitochondrial-based ATP synthesis. Ultrastructural analysis of the oocyte cytoplasm demonstrated increased mitochondrial length in the presence of RNS60-based Ringer's solution. It is concluded that the biological properties of RNS60 relate to its ability to optimize ATP synthesis. PMID:25742953

A magic bullet to specifically eliminate mutated mitochondrial genomes from patients' cells

PubMed Central

Moraes, Carlos T

2014-01-01

When mitochondrial diseases result from mutations found in the mitochondrial DNA, engineered mitochondrial-targeted nucleases such as mitochondrial-targeted zinc finger nucleases are shown to specifically eliminate the mutated molecules, leaving the wild-type mitochondrial DNA intact to replicate and restore normal copy number. In this issue, Gammage and colleagues successfully apply this improved technology on patients' cells with two types of genetic alterations responsible for neuropathy ataxia and retinitis pigmentosa (NARP) syndrome and Kearns Sayre syndrome and progressive external ophthalmoplegia (PEO). PMID:24623377

Syndromes associated with mitochondrial DNA depletion

PubMed Central

2014-01-01

Mitochondrial dysfunction accounts for a large group of inherited metabolic disorders most of which are due to a dysfunctional mitochondrial respiratory chain (MRC) and, consequently, deficient energy production. MRC function depends on the coordinated expression of both nuclear (nDNA) and mitochondrial (mtDNA) genomes. Thus, mitochondrial diseases can be caused by genetic defects in either the mitochondrial or the nuclear genome, or in the cross-talk between the two. This impaired cross-talk gives rise to so-called nuclear-mitochondrial intergenomic communication disorders, which result in loss or instability of the mitochondrial genome and, in turn, impaired maintenance of qualitative and quantitative mtDNA integrity. In children, most MRC disorders are associated with nuclear gene defects rather than alterations in the mtDNA itself. The mitochondrial DNA depletion syndromes (MDSs) are a clinically heterogeneous group of disorders with an autosomal recessive pattern of transmission that have onset in infancy or early childhood and are characterized by a reduced number of copies of mtDNA in affected tissues and organs. The MDSs can be divided into least four clinical presentations: hepatocerebral, myopathic, encephalomyopathic and neurogastrointestinal. The focus of this review is to offer an overview of these syndromes, listing the clinical phenotypes, together with their relative frequency, mutational spectrum, and possible insights for improving diagnostic strategies. PMID:24708634

Cancer: Mitochondrial Origins.

PubMed

Stefano, George B; Kream, Richard M

2015-12-01

The primacy of glucose derived from photosynthesis as an existential source of chemical energy across plant and animal phyla is universally accepted as a core principle in the biological sciences. In mammalian cells, initial processing of glucose to triose phosphate intermediates takes place within the cytosolic glycolytic pathway and terminates with temporal transport of reducing equivalents derived from pyruvate metabolism by membrane-associated respiratory complexes in the mitochondrial matrix. The intra-mitochondrial availability of molecular oxygen as the ultimate electron acceptor drives the evolutionary fashioned chemiosmotic production of ATP as a high-efficiency biological process. The mechanistic bases of carcinogenesis have demonstrated profound alteration of normative mitochondrial function, notably dysregulated respiratory processes. Accordingly, the classic Warburg effect functionally links aerobic glycolysis, aberrant production and release of lactate, and metabolic down-regulation of mitochondrial oxidative processes with the carcinogenetic phenotype. We surmise, however, that aerobic fermentation by cancer cells may also represent a developmental re-emergence of an evolutionarily conserved early phenotype, which was "sidelined" with the emergence of mitochondrial oxidative phosphorylation as a primary mechanism for ATP production in normal cells. Regardless of state-dependent physiological status in mixed populations of cancer cells, it has been established that mitochondria are functionally linked to the initiation of cancer and its progression. Biochemical, molecular, and physiological differences in cancer cell mitochondria, notably mtDNA heteroplasmy and allele-specific expression of selected nuclear genes, may represent major focal points for novel targeting and elimination of cancer cells in metastatic disease afflicting human populations. To date, and despite considerable research efforts, the practical realization of advanced mitochondrial

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

Role of Mitochondrial Homeostasis and Dynamics in Alzheimer’s Disease

PubMed Central

Selfridge, J. Eva; Lezi, E; Lu, Jianghua; Swerdlow, Russell H.

2012-01-01

Alzheimer’s disease (AD) is a progressive neurodegenerative disease that affects a staggering percentage of the aging population and causes memory loss and cognitive decline. Mitochondrial abnormalities can be observed systemically and in brains of patients suffering from AD, and may account for part of the disease phenotype. In this review, we summarize some of the key findings that indicate mitochondrial dysfunction is present in AD-affected subjects, including cytochrome oxidase deficiency, endophenotype data, and altered mitochondrial morphology. Special attention is given to recently described perturbations in mitochondrial autophagy, fission-fusion dynamics, and biogenesis. We also briefly discuss how mitochondrial dysfunction may influence amyloidosis in Alzheimer’s disease, why mitochondria are a valid therapeutic target, and strategies for addressing AD-specific mitochondrial dysfunction. PMID:22266017

Inflammation alters regional mitochondrial Ca²+ in human airway smooth muscle cells.

PubMed

Delmotte, Philippe; Yang, Binxia; Thompson, Michael A; Pabelick, Christina M; Prakash, Y S; Sieck, Gary C

2012-08-01

Regulation of cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in airway smooth muscle (ASM) is a key aspect of airway contractility and can be modulated by inflammation. Mitochondria have tremendous potential for buffering [Ca(2+)](cyt), helping prevent Ca(2+) overload, and modulating other intracellular events. Here, compartmentalization of mitochondria to different cellular regions may subserve different roles. In the present study, we examined the role of Ca(2+) buffering by mitochondria and mitochondrial Ca(2+) transport mechanisms in the regulation of [Ca(2+)](cyt) in enzymatically dissociated human ASM cells upon exposure to the proinflammatory cytokines TNF-α and IL-13. Cells were loaded simultaneously with fluo-3 AM and rhod-2 AM, and [Ca(2+)](cyt) and mitochondrial Ca(2+) concentration ([Ca(2+)](mito)) were measured, respectively, using real-time two-color fluorescence microscopy in both the perinuclear and distal, perimembranous regions of cells. Histamine induced a rapid increase in both [Ca(2+)](cyt) and [Ca(2+)](mito), with a significant delay in the mitochondrial response. Inhibition of the mitochondrial Na(+)/Ca(2+) exchanger (1 μM CGP-37157) increased [Ca(2+)](mito) responses in perinuclear mitochondria but not distal mitochondria. Inhibition of the mitochondrial uniporter (1 μM Ru360) decreased [Ca(2+)](mito) responses in perinuclear and distal mitochondria. CGP-37157 and Ru360 significantly enhanced histamine-induced [Ca(2+)](cyt). TNF-α and IL-13 both increased [Ca(2+)](cyt), which was associated with decreased [Ca(2+)](mito) in the case of TNF-α but not IL-13. The effects of TNF-α on both [Ca(2+)](cyt) and [Ca(2+)](mito) were affected by CGP-37157 but not by Ru360. Overall, these data demonstrate that in human ASM cells, mitochondria buffer [Ca(2+)](cyt) after agonist stimulation and its enhancement by inflammation. The differential regulation of [Ca(2+)](mito) in different parts of ASM cells may serve to locally regulate Ca(2+) fluxes from

Inherited Mitochondrial Diseases of DNA Replication

PubMed Central

Copeland, William C.

2007-01-01

Mitochondrial genetic diseases can result from defects in mitochondrial DNA (mtDNA) in the form of deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These mutations may be spontaneous, maternally inherited, or a result of inherited nuclear defects in genes that maintain mtDNA. This review focuses on our current understanding of nuclear gene mutations that produce mtDNA alterations and cause mitochondrial depletion syndrome (MDS), progressive external ophthalmoplegia (PEO), ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). To date, all of these etiologic nuclear genes fall into one of two categories: genes whose products function directly at the mtDNA replication fork, such as POLG, POLG2, and TWINKLE, or genes whose products supply the mitochondria with deoxynucleotide triphosphate pools needed for DNA replication, such as TK2, DGUOK, TP, SUCLA2, ANT1, and possibly the newly identified MPV17. PMID:17892433

Alterations in the mitochondrial regulatory pathways constituted by the nuclear co-factors PGC-1alpha or PGC-1beta and mitofusin 2 in skeletal muscle in type 2 diabetes.

PubMed

Zorzano, Antonio; Hernández-Alvarez, María Isabel; Palacín, Manuel; Mingrone, Geltrude

2010-01-01

Muscle mitochondrial metabolism is regulated by a number of factors, many of which are responsible for the transcription of nuclear genes encoding mitochondrial proteins such as PPARdelta, PGC-1alpha or PGC-1beta. Recent evidence indicates that proteins participating in mitochondrial dynamics also regulate mitochondrial metabolism. Thus, in cultured cells the mitochondrial fusion protein mitofusin 2 (Mfn2) stimulates respiration, substrate oxidation and the expression of subunits involved in respiratory complexes. Mitochondrial dysfunction has been reported in skeletal muscle of type 2 diabetic patients. Reduced mitochondrial mass and defective activity has been proposed to explain this dysfunction. Alterations in mitochondrial metabolism may be crucial to account for some of the pathophysiological traits that characterize type 2 diabetes. Skeletal muscle of type 2 diabetic patients shows reduced expression of PGC-1alpha, PGC-1beta, and Mfn2. In addition, a differential response to bilio-pancreatic diversion-induced weight loss in non-diabetic and type 2 diabetic patients has been reported. While non-diabetic morbidly obese subjects showed an increased expression of genes encoding Mfn2, PGC-1alpha, PGC-1beta, PPARdelta or SIRT1 in response to bariatric surgery-induced weight loss, no effect was detected in type 2 diabetic patients. These observations suggest the existence of a heritable component responsible for the abnormal control of the expression of genes encoding for modulators of mitochondrial biogenesis/metabolism, and which may participate in the development of the disease. Copyright © 2010 Elsevier B.V. All rights reserved.

Oxidative stress and mitochondrial dysfunction in Kindler syndrome.

PubMed

Zapatero-Solana, Elisabeth; García-Giménez, Jose Luis; Guerrero-Aspizua, Sara; García, Marta; Toll, Agustí; Baselga, Eulalia; Durán-Moreno, Maria; Markovic, Jelena; García-Verdugo, Jose Manuel; Conti, Claudio J; Has, Cristina; Larcher, Fernando; Pallardó, Federico V; Del Rio, Marcela

2014-12-21

Kindler Syndrome (KS) is an autosomal recessive skin disorder characterized by skin blistering, photosensitivity, premature aging, and propensity to skin cancer. In spite of the knowledge underlying cause of this disease involving mutations of FERMT1 (fermitin family member 1), and efforts to characterize genotype-phenotype correlations, the clinical variability of this genodermatosis is still poorly understood. In addition, several pathognomonic features of KS, not related to skin fragility such as aging, inflammation and cancer predisposition have been strongly associated with oxidative stress. Alterations of the cellular redox status have not been previously studied in KS. Here we explored the role of oxidative stress in the pathogenesis of this rare cutaneous disease. Patient-derived keratinocytes and their respective controls were cultured and classified according to their different mutations by PCR and western blot, the oxidative stress biomarkers were analyzed by spectrophotometry and qPCR and additionally redox biosensors experiments were also performed. The mitochondrial structure and functionality were analyzed by confocal microscopy and electron microscopy. Patient-derived keratinocytes showed altered levels of several oxidative stress biomarkers including MDA (malondialdehyde), GSSG/GSH ratio (oxidized and reduced glutathione) and GCL (gamma-glutamyl cysteine ligase) subunits. Electron microscopy analysis of both, KS skin biopsies and keratinocytes showed marked morphological mitochondrial abnormalities. Consistently, confocal microscopy studies of mitochondrial fluorescent probes confirmed the mitochondrial derangement. Imbalance of oxidative stress biomarkers together with abnormalities in the mitochondrial network and function are consistent with a pro-oxidant state. This is the first study to describe mitochondrial dysfunction and oxidative stress involvement in KS.

NITRIC OXIDE, MITOCHONDRIAL HYPERPOLARIZATION AND T-CELL ACTIVATION

PubMed Central

Nagy, Gyorgy; Koncz, Agnes; Fernandez, David; Perl, Andras

2007-01-01

T lymphocyte activation is associated with nitric oxide (NO) production that plays an essential role in multiple T cell functions. NO acts as a messenger, activating soluble guanyl cyclase and participating in the transduction signaling pathways involving cyclic GMP. NO modulates mitochondrial events that are involved in apoptosis and regulates mitochondrial membrane potential and mitochondrial biogenesis in many cell types, including lymphocytes. Mitochondrial hyperpolarization (MHP), an early and reversible event during both T lymphocyte activation and apoptosis, is regulated by NO. Here, we discuss recent evidence that NO-induced MHP represents a molecular switch in multiple T cell signaling pathways. Overproduction of NO in systemic lupus erythematosus (SLE) induces mitochondrial biogenesis and alters Ca2+ signaling. Thus, while NO plays a physiological role in lymphocyte cell signaling, its overproduction may disturb normal T cell function, contributing to the pathogenesis of autoimmunity. PMID:17462531

Altered Mitochondrial DNA Methylation Pattern in Alzheimer Disease-Related Pathology and in Parkinson Disease.

PubMed

Blanch, Marta; Mosquera, Jose Luis; Ansoleaga, Belén; Ferrer, Isidre; Barrachina, Marta

2016-02-01

Mitochondrial dysfunction is linked with the etiopathogenesis of Alzheimer disease and Parkinson disease. Mitochondria are intracellular organelles essential for cell viability and are characterized by the presence of the mitochondrial (mt)DNA. DNA methylation is a well-known epigenetic mechanism that regulates nuclear gene transcription. However, mtDNA methylation is not the subject of the same research attention. The present study shows the presence of mitochondrial 5-methylcytosine in CpG and non-CpG sites in the entorhinal cortex and substantia nigra of control human postmortem brains, using the 454 GS FLX Titanium pyrosequencer. Moreover, increased mitochondrial 5-methylcytosine levels are found in the D-loop region of mtDNA in the entorhinal cortex in brain samples with Alzheimer disease-related pathology (stages I to II and stages III to IV of Braak and Braak; n = 8) with respect to control cases. Interestingly, this region shows a dynamic pattern in the content of mitochondrial 5-methylcytosine in amyloid precursor protein/presenilin 1 mice along with Alzheimer disease pathology progression (3, 6, and 12 months of age). Finally, a loss of mitochondrial 5-methylcytosine levels in the D-loop region is found in the substantia nigra in Parkinson disease (n = 10) with respect to control cases. In summary, the present findings suggest mtDNA epigenetic modulation in human brain is vulnerable to neurodegenerative disease states. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Mitochondrial DNA copy numbers in pyramidal neurons are decreased and mitochondrial biogenesis transcriptome signaling is disrupted in Alzheimer's disease hippocampi.

PubMed

Rice, Ann C; Keeney, Paula M; Algarzae, Norah K; Ladd, Amy C; Thomas, Ravindar R; Bennett, James P

2014-01-01

Alzheimer's disease (AD) is the major cause of adult-onset dementia and is characterized in its pre-diagnostic stage by reduced cerebral cortical glucose metabolism and in later stages by reduced cortical oxygen uptake, implying reduced mitochondrial respiration. Using quantitative PCR we determined the mitochondrial DNA (mtDNA) gene copy numbers from multiple groups of 15 or 20 pyramidal neurons, GFAP(+) astrocytes and dentate granule neurons isolated using laser capture microdissection, and the relative expression of mitochondrial biogenesis (mitobiogenesis) genes in hippocampi from 10 AD and 9 control (CTL) cases. AD pyramidal but not dentate granule neurons had significantly reduced mtDNA copy numbers compared to CTL neurons. Pyramidal neuron mtDNA copy numbers in CTL, but not AD, positively correlated with cDNA levels of multiple mitobiogenesis genes. In CTL, but not in AD, hippocampal cDNA levels of PGC1α were positively correlated with multiple downstream mitobiogenesis factors. Mitochondrial DNA copy numbers in pyramidal neurons did not correlate with hippocampal Aβ1-42 levels. After 48 h exposure of H9 human neural stem cells to the neurotoxic fragment Aβ25-35, mtDNA copy numbers were not significantly altered. In summary, AD postmortem hippocampal pyramidal neurons have reduced mtDNA copy numbers. Mitochondrial biogenesis pathway signaling relationships are disrupted in AD, but are mostly preserved in CTL. Our findings implicate complex alterations of mitochondria-host cell relationships in AD.

UBIAD1 Mutation Alters a Mitochondrial Prenyltransferase to Cause Schnyder Corneal Dystrophy

PubMed Central

Nickerson, Michael L.; Kostiha, Brittany N.; Brandt, Wolfgang; Fredericks, William; Xu, Ke-Ping; Yu, Fu-Shin; Gold, Bert; Chodosh, James; Goldberg, Marc; Lu, Da Wen; Yamada, Masakazu; Tervo, Timo M.; Grutzmacher, Richard; Croasdale, Chris; Hoeltzenbein, Maria; Sutphin, John; Malkowicz, S. Bruce; Wessjohann, Ludger; Kruth, Howard S.; Dean, Michael; Weiss, Jayne S.

2010-01-01

Background Mutations in a novel gene, UBIAD1, were recently found to cause the autosomal dominant eye disease Schnyder corneal dystrophy (SCD). SCD is characterized by an abnormal deposition of cholesterol and phospholipids in the cornea resulting in progressive corneal opacification and visual loss. We characterized lesions in the UBIAD1 gene in new SCD families and examined protein homology, localization, and structure. Methodology/Principal Findings We characterized five novel mutations in the UBIAD1 gene in ten SCD families, including a first SCD family of Native American ethnicity. Examination of protein homology revealed that SCD altered amino acids which were highly conserved across species. Cell lines were established from patients including keratocytes obtained after corneal transplant surgery and lymphoblastoid cell lines from Epstein-Barr virus immortalized peripheral blood mononuclear cells. These were used to determine the subcellular localization of mutant and wild type protein, and to examine cholesterol metabolite ratios. Immunohistochemistry using antibodies specific for UBIAD1 protein in keratocytes revealed that both wild type and N102S protein were localized sub-cellularly to mitochondria. Analysis of cholesterol metabolites in patient cell line extracts showed no significant alteration in the presence of mutant protein indicating a potentially novel function of the UBIAD1 protein in cholesterol biochemistry. Molecular modeling was used to develop a model of human UBIAD1 protein in a membrane and revealed potentially critical roles for amino acids mutated in SCD. Potential primary and secondary substrate binding sites were identified and docking simulations indicated likely substrates including prenyl and phenolic molecules. Conclusions/Significance Accumulating evidence from the SCD familial mutation spectrum, protein homology across species, and molecular modeling suggest that protein function is likely down-regulated by SCD mutations

Phenyl-alpha-tert-butyl nitrone reverses mitochondrial decay in acute Chagas' disease.

PubMed

Wen, Jian-Jun; Bhatia, Vandanajay; Popov, Vsevolod L; Garg, Nisha Jain

2006-12-01

In this study, we investigated the mechanism(s) of mitochondrial functional decline in acute Chagas' disease. Our data show a substantial decline in respiratory complex activities (39 to 58%) and ATP (38%) content in Trypanosoma cruzi-infected murine hearts compared with normal controls. These metabolic alterations were associated with an approximately fivefold increase in mitochondrial reactive oxygen species production rate, substantial oxidative insult of mitochondrial membranes and respiratory complex subunits, and >60% inhibition of mtDNA-encoded transcripts for respiratory complex subunits in infected myocardium. The antioxidant phenyl-alpha-tert-butyl nitrone (PBN) arrested the oxidative damage-mediated loss in mitochondrial membrane integrity, preserved redox potential-coupled mitochondrial gene expression, and improved respiratory complex activities (47 to 95% increase) and cardiac ATP level (>or=40% increase) in infected myocardium. Importantly, PBN resulted twofold decline in mitochondrial reactive oxygen species production rate in infected myocardium. Taken together, our data demonstrate the pathological significance of oxidative stress in metabolic decay and energy homeostasis in acute chagasic myocarditis and further suggest that oxidative injuries affecting mitochondrial integrity-dependent expression and activity of the respiratory complexes initiate a feedback cycle of electron transport chain inefficiency, increased reactive oxygen species production, and energy homeostasis in acute chagasic hearts. PBN and other mitochondria-targeted antioxidants may be useful in altering mitochondrial decay and oxidative pathology in Chagas' disease.

SLC25A46 is required for mitochondrial lipid homeostasis and cristae maintenance and is responsible for Leigh syndrome.

PubMed

Janer, Alexandre; Prudent, Julien; Paupe, Vincent; Fahiminiya, Somayyeh; Majewski, Jacek; Sgarioto, Nicolas; Des Rosiers, Christine; Forest, Anik; Lin, Zhen-Yuan; Gingras, Anne-Claude; Mitchell, Grant; McBride, Heidi M; Shoubridge, Eric A

2016-09-01

Mitochondria form a dynamic network that responds to physiological signals and metabolic stresses by altering the balance between fusion and fission. Mitochondrial fusion is orchestrated by conserved GTPases MFN1/2 and OPA1, a process coordinated in yeast by Ugo1, a mitochondrial metabolite carrier family protein. We uncovered a homozygous missense mutation in SLC25A46, the mammalian orthologue of Ugo1, in a subject with Leigh syndrome. SLC25A46 is an integral outer membrane protein that interacts with MFN2, OPA1, and the mitochondrial contact site and cristae organizing system (MICOS) complex. The subject mutation destabilizes the protein, leading to mitochondrial hyperfusion, alterations in endoplasmic reticulum (ER) morphology, impaired cellular respiration, and premature cellular senescence. The MICOS complex is disrupted in subject fibroblasts, resulting in strikingly abnormal mitochondrial architecture, with markedly shortened cristae. SLC25A46 also interacts with the ER membrane protein complex EMC, and phospholipid composition is altered in subject mitochondria. These results show that SLC25A46 plays a role in a mitochondrial/ER pathway that facilitates lipid transfer, and link altered mitochondrial dynamics to early-onset neurodegenerative disease and cell fate decisions. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

Phloretin ameliorates arsenic trioxide induced mitochondrial dysfunction in H9c2 cardiomyoblasts mediated via alterations in membrane permeability and ETC complexes.

PubMed

Vineetha, Vadavanath Prabhakaran; Soumya, Rema Sreenivasan; Raghu, Kozhiparambil Gopalan

2015-05-05

Arsenic trioxide (ATO), though a very effective drug for the treatment of acute promyelocytic leukemia, leads to cardiotoxicity. As mitochondria are the center of attention of cardiac cell׳s general metabolic status, it is primarily important to see the interaction of ATO with mitochondria. Studies related exclusively to the alterations in mitochondria and its associated functions caused by ATO are very limited. The present investigation aims to explore the effect of ATO on various components of electron transport chain, oxygen consumption, ATP production, mitochondrial superoxide generation, transmembrane potential, permeability pore opening, calcium homeostasis and apoptosis. Attempts were also made to see the efficacy of phloretin, a potent antioxidant flavonoid found majorly in apple peel on cardiotoxicity. The H9c2 cells exposed to ATO (5µM) exhibited increased oxidative stress with reduced innate antioxidant status, mitochondrial dysfunctions and apoptosis. It increased the intracellular calcium content, caused alterations in the activity of transcription factor Nrf2, xanthine oxidase, aconitase and caspase 3 compared to the control group. Phloretin at 2.5 and 5µM concentrations were able to protect the cells from ATO toxicity via protecting mitochondria through its antioxidant potential. The present investigation based on mitochondria reveals the probability of cardioprotective potential of phloretin for the cancer patients on ATO chemotherapy. Copyright © 2015 Elsevier B.V. All rights reserved.

Ethanol induced hepatic mitochondrial dysfunction is attenuated by all trans retinoic acid supplementation.

PubMed

Nair, Saritha S; Prathibha, P; Rejitha, S; Indira, M

2015-08-15

Alcoholics have reduced vitamin A levels in serum since vitamin A and ethanol share the same metabolic pathway. Vitamin A supplementation has an additive effect on ethanol induced toxicity. Hence in this study, we assessed the impact of supplementation of all trans retinoic acid (ATRA), an active metabolite of vitamin A on ethanol induced disruptive alterations in liver mitochondria. Male Sprague Dawley rats were grouped as follows: I: Control; II: Ethanol (4 g/kg b.wt./day); III: ATRA (100 μg/kg b.wt./day); and IV: Ethanol (4 g/kg b.wt./day)+ATRA (100 μg/kg b.wt./day). Duration of the experiment was 90 days, after which the animals were sacrificed for the study. The key enzymes of energy metabolism, reactive oxygen species, mitochondrial membrane potential and hepatic mRNA expressions of Bax, Bcl-2, c-fos and c-jun were assessed. Ethanol administration increased the reactive oxygen species generation in mitochondria. It also decreased the activities of the enzymes of citric acid cycle and oxidative phosphorylation. ATP content and mitochondrial membrane potential were decreased and cytosolic cytochrome c was increased consequently enhancing apoptosis. All these alterations were altered significantly on ATRA supplementation along with ethanol. These results were reinforced by our histopathological studies. ATRA supplementation to ethanol fed rats, led to reduction in oxidative stress, decreased calcium overload in the matrix and increased mitochondrial membrane potential, which might have altered the mitochondrial energy metabolism and elevated ATP production thereby reducing the apoptotic alterations. Hence ATRA supplementation seemed to be an effective intervention against alcohol induced mitochondrial dysfunction. Copyright © 2015 Elsevier Inc. All rights reserved.

Mitochondrial Pyruvate Carrier Function and Cancer Metabolism

PubMed Central

Rauckhorst, Adam J.

2016-01-01

Metabolic reprograming in cancer supports the increased biosynthesis required for unchecked proliferation. Increased glucose utilization is a defining feature of many cancers that is accompanied by altered pyruvate partitioning and mitochondrial metabolism. Cancer cells also require mitochondrial tricarboxylic acid cycle activity and electron transport chain function for biosynthetic competency and proliferation. Recent evidence demonstrates that mitochondrial pyruvate carrier (MPC) function is abnormal in some cancers and that increasing MPC activity may decrease cancer proliferation. Here we examine recent findings on MPC function and cancer metabolism. Special emphasis is placed on the compartmentalization of pyruvate metabolism and the alternative routes of metabolism that maintain the cellular biosynthetic pools required for unrestrained proliferation in cancer. PMID:27269731

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.

Decreasing mitochondrial fission alleviates hepatic steatosis in a murine model of nonalcoholic fatty liver disease.

PubMed

Galloway, Chad A; Lee, Hakjoo; Brookes, Paul S; Yoon, Yisang

2014-09-15

Mitochondria produce the majority of cellular ATP through oxidative phosphorylation, and their capacity to do so is influenced by many factors. Mitochondrial morphology is recently suggested as an important contributor in controlling mitochondrial bioenergetics. Mitochondria divide and fuse continuously, which is affected by environmental factors, including metabolic alterations. Underscoring its bioenergetic influence, altered mitochondrial morphology is reported in tissues of patients and in animal models of metabolic dysfunction. In this study, we found that mitochondrial fission plays a vital role in the progression of nonalcoholic fatty liver disease (NAFLD). The development of hepatic steatosis, oxidative/nitrative stress, and hepatic tissue damage, induced by a high-fat diet, were alleviated in genetically manipulated mice suppressing mitochondrial fission. The alleviation of steatosis was recapitulated in primary hepatocytes with the inhibition of mitochondrial fission. Mechanistically, our study indicates that fission inhibition enhances proton leak under conditions of free fatty acid incubation, implicating bioenergetic change through manipulating mitochondrial fission. Taken together, our results suggest a mechanistic role for mitochondrial fission in the etiology of NAFLD. The efficacy of decreasing mitochondrial fission in the suppression of NAFLD suggests that mitochondrial fission represents a novel target for therapeutic treatment of NAFLD. Copyright © 2014 the American Physiological Society.

Sexual Dimorphism in the Alterations of Cardiac Muscle Mitochondrial Bioenergetics Associated to the Ageing Process.

PubMed

Colom, Bartomeu; Oliver, Jordi; Garcia-Palmer, Francisco J

2015-11-01

The incidence of cardiac disease is age and sex dependent, but the mechanisms governing these associations remain poorly understood. Mitochondria are the organelles in charge of producing energy for the cells, and their malfunction has been linked to cardiovascular disease and heart failure. Interestingly, heart mitochondrial content and functionality are also age and sex dependent. Here we investigated the combinatory effects of age and sex in mitochondrial bioenergetics that could help to understand their role on cardiac disease. Cardiac mitochondria from 6- and 24-month-old male and female Wistar rats were isolated, and the enzymatic activities of the oxidative-phosphorylative complexes I, III, and IV and ATPase, as well as the protein levels of complex IV, β-ATPase, and mitochondrial transcription factor A (TFAM), were measured. Furthermore, heart DNA content, citrate synthase activity, mitochondrial protein content, oxygen consumption, and H2O2 generation were also determined. Results showed a reduction in heart mitochondrial mass and functionality with age that correlated with increased H2O2 generation. Moreover, sex-dependent differences were found in several of these parameters. In particular, old females exhibited a significant loss of mitochondrial function and increased relative H2O2 production compared with their male counterparts. The results demonstrate a sex dimorphism in the age-associated defects on cardiac mitochondrial function. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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

Application of a random walk model to geographic distributions of animal mitochondrial DNA variation.

PubMed

Neigel, J E; Avise, J C

1993-12-01

In rapidly evolving molecules, such as animal mitochondrial DNA, mutations that delineate specific lineages may not be dispersed at sufficient rates to attain an equilibrium between genetic drift and gene flow. Here we predict conditions that lead to nonequilibrium geographic distributions of mtDNA lineages, test the robustness of these predictions and examine mtDNA data sets for consistency with our model. Under a simple isolation by distance model, the variance of an mtDNA lineage's geographic distribution is expected be proportional to its age. Simulation results indicated that this relationship is fairly robust. Analysis of mtDNA data from natural populations revealed three qualitative distributional patterns: (1) significant departure of lineage structure from equilibrium geographic distributions, a pattern exhibited in three rodent species with limited dispersal; (2) nonsignificant departure from equilibrium expectations, exhibited by two avian and two marine fish species with potentials for relatively long-distance dispersal; and (3) a progression from nonequilibrium distributions for younger lineages to equilibrium distributions for older lineages, a condition displayed by one surveyed avian species. These results demonstrate the advantages of considering mutation and genealogy in the interpretation of mtDNA geographic variation.

Abnormal permeability of inner and outer mitochondrial membranes contributes independently to mitochondrial dysfunction in the liver during acute endotoxemia.

PubMed

Crouser, Elliott D; Julian, Mark W; Huff, Jennifer E; Joshi, Mandar S; Bauer, John A; Gadd, Martha E; Wewers, Mark D; Pfeiffer, Douglas R

2004-02-01

This study was designed to determine the role played by the mitochondrial permeability transition in the pathogenesis of mitochondrial damage and dysfunction in a representative systemic organ during the acute phase of endotoxemia. A well-established, normotensive feline model was employed to determine whether pretreatment with cyclosporine A, a potent inhibitor of the mitochondrial permeability transition, normalizes mitochondrial ultrastructural injury and dysfunction in the liver during acute endotoxemia. The Ohio State University Medical Center research laboratory. Random source, adult, male conditioned cats. Hemodynamic resuscitation and maintenance of acid-base balance and tissue oxygen availability were provided, as needed, to minimize the potentially confounding effects of tissue hypoxia and/or acidosis on the experimental results. Treatment groups received isotonic saline vehicle (control; n = 6), lipopolysaccharide (3.0 mg/kg, intravenously; n = 8), or cyclosporine A (6.0 mg/kg, intravenously; n = 6) or tacrolimus (FK506, 0.1 mg/kg, intravenously; n = 4) followed in 30 mins by lipopolysaccharide (3.0 mg/kg, intravenously). Liver samples were obtained 4 hrs posttreatment, and mitochondrial ultrastructure, function, and cytochrome c, Bax, and ceramide contents were assessed. As expected, significant mitochondrial injury was apparent in the liver 4 hrs after lipopolysaccharide treatment, despite maintenance of regional tissue oxygen availability. Namely, mitochondria demonstrated high-amplitude swelling and exhibited altered respiratory function. Cyclosporine A pretreatment attenuated lipopolysaccharide-induced mitochondrial ultrastructural abnormalities and normalized mitochondrial respiratory control, reflecting protection against inner mitochondrial membrane damage. However, an abnormal permeability of outer mitochondrial membranes to cytochrome c was observed in all lipopolysaccharide-treated groups and was associated with increased mitochondrial

Altering CO2 during reperfusion of ischemic cardiomyocytes modifies mitochondrial oxidant injury.

PubMed

Lavani, Romeen; Chang, Wei-Tien; Anderson, Travis; Shao, Zuo-Hui; Wojcik, Kimberly R; Li, Chang-Qing; Pietrowski, Robert; Beiser, David G; Idris, Ahamed H; Hamann, Kimm J; Becker, Lance B; Vanden Hoek, Terry L

2007-07-01

species. Altering CO2 content during reperfusion can significantly affect myocardial postresuscitation injury, in part by modifying mitochondrial oxidants and NO synthase-induced NO production.

Mitochondrial control of cell bioenergetics in Parkinson’s disease

PubMed Central

Requejo-Aguilar, Raquel; Bolaños, Juan P.

2016-01-01

Parkinson disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra. The earliest biochemical signs of the disease involve failure in mitochondrial-endoplasmic reticulum cross talk and lysosomal function, mitochondrial electron chain impairment, mitochondrial dynamics alterations, and calcium and iron homeostasis abnormalities. These changes are associated with increased mitochondrial reactive oxygen species (mROS) and energy deficiency. Recently, it has been reported that, as an attempt to compensate for the mitochondrial dysfunction, neurons invoke glycolysis as a low-efficient mode of energy production in models of PD. Here, we review how mitochondria orchestrate the maintenance of cellular energetic status in PD, with special focus on the switch from oxidative phosphorylation to glycolysis, as well as the implication of endoplasmic reticulum and lysosomes in the control of bioenergetics. PMID:27091692

Pancreatic β-Cell Dysfunction in Diet-Induced Obese Mice: Roles of AMP-Kinase, Protein Kinase Cε, Mitochondrial and Cholesterol Metabolism, and Alterations in Gene Expression

PubMed Central

Pepin, Émilie; Al-Mass, Anfal; Attané, Camille; Zhang, Kezhuo; Lamontagne, Julien; Lussier, Roxane; Madiraju, S. R. Murthy; Joly, Erik; Ruderman, Neil B.; Sladek, Robert; Prentki, Marc; Peyot, Marie-Line

2016-01-01

Diet induced obese (DIO) mice can be stratified according to their weight gain in response to high fat diet as low responders (LDR) and high responders (HDR). This allows the study of β-cell failure and the transitions to prediabetes (LDR) and early diabetes (HDR). C57BL/6N mice were fed for 8 weeks with a normal chow diet (ND) or a high fat diet and stratified as LDR and HDR. Freshly isolated islets from ND, LDR and HDR mice were studied ex-vivo for mitochondrial metabolism, AMPK activity and signalling, the expression and activity of key enzymes of energy metabolism, cholesterol synthesis, and mRNA profiling. Severely compromised glucose-induced insulin secretion in HDR islets, as compared to ND and LDR islets, was associated with suppressed AMP-kinase activity. HDR islets also showed reduced acetyl-CoA carboxylase activity and enhanced activity of 3-hydroxy-3-methylglutaryl-CoA reductase, which led respectively to elevated fatty acid oxidation and increased cholesterol biosynthesis. HDR islets also displayed mitochondrial membrane hyperpolarization and reduced ATP turnover in the presence of elevated glucose. Expression of protein kinase Cε, which reduces both lipolysis and production of signals for insulin secretion, was elevated in DIO islets. Genes whose expression increased or decreased by more than 1.2-fold were minor between LDR and ND islets (17 differentially expressed), but were prominent between HDR and ND islets (1508 differentially expressed). In HDR islets, particularly affected genes were related to cell cycle and proliferation, AMPK signaling, mitochondrial metabolism and cholesterol metabolism. In conclusion, chronically reduced AMPK activity, mitochondrial dysfunction, elevated cholesterol biosynthesis in islets, and substantial alterations in gene expression accompany β-cell failure in HDR islets. The β-cell compensation process in the prediabetic state (LDR) is largely independent of transcriptional adaptive changes, whereas the transition

Lycopene Prevents Amyloid [Beta]-Induced Mitochondrial Oxidative Stress and Dysfunctions in Cultured Rat Cortical Neurons.

PubMed

Qu, Mingyue; Jiang, Zheng; Liao, Yuanxiang; Song, Zhenyao; Nan, Xinzhong

2016-06-01

Brains affected by Alzheimer's disease (AD) show a large spectrum of mitochondrial alterations at both morphological and genetic level. The causal link between β-amyloid (Aβ) and mitochondrial dysfunction has been established in cellular models of AD. We observed previously that lycopene, a member of the carotenoid family of phytochemicals, could counteract neuronal apoptosis and cell damage induced by Aβ and other neurotoxic substances, and that this neuroprotective action somehow involved the mitochondria. The present study aims to investigate the effects of lycopene on mitochondria in cultured rat cortical neurons exposed to Aβ. It was found that lycopene attenuated Aβ-induced oxidative stress, as evidenced by the decreased intracellular reactive oxygen species generation and mitochondria-derived superoxide production. Additionally, lycopene ameliorated Aβ-induced mitochondrial morphological alteration, opening of the mitochondrial permeability transition pores and the consequent cytochrome c release. Lycopene also improved mitochondrial complex activities and restored ATP levels in Aβ-treated neuron. Furthermore, lycopene prevented mitochondrial DNA damages and improved the protein level of mitochondrial transcription factor A in mitochondria. Those results indicate that lycopene protects mitochondria against Aβ-induced damages, at least in part by inhibiting mitochondrial oxidative stress and improving mitochondrial function. These beneficial effects of lycopene may account for its protection against Aβ-induced neurotoxicity.

SLP-2 negatively modulates mitochondrial sodium-calcium exchange.

PubMed

Da Cruz, Sandrine; De Marchi, Umberto; Frieden, Maud; Parone, Philippe A; Martinou, Jean-Claude; Demaurex, Nicolas

2010-01-01

Mitochondria play a major role in cellular calcium homeostasis. Despite decades of studies, the molecules that mediate and regulate the transport of calcium ions in and out of the mitochondrial matrix remain unknown. Here, we investigate whether SLP-2, an inner membrane mitochondrial protein of unknown function, modulates the activity of mitochondrial Ca(2+) transporters. In HeLa cells depleted of SLP-2, the amplitude and duration of mitochondrial Ca(2+) elevations evoked by agonists were decreased compared to control cells. SLP-2 depletion increased the rates of calcium extrusion from mitochondria. This effect disappeared upon Na(+) removal or addition of CGP-37157, an inhibitor of the mitochondrial Na(+)/Ca(2+) exchanger, and persisted in permeabilized cells exposed to a fixed cytosolic Na(+) and Ca(2+) concentration. The rates of mitochondrial Ca(2+) extrusion were prolonged in SLP-2 over-expressing cells, independently of the amplitude of mitochondrial Ca(2+) elevations. The amplitude of cytosolic Ca(2+) elevations was increased by SLP-2 depletion and decreased by SLP-2 over-expression. These data show that SLP-2 modulates mitochondrial calcium extrusion, thereby altering the ability of mitochondria to buffer Ca(2+) and to shape cytosolic Ca(2+) signals. 2009 Elsevier Ltd. All rights reserved.

Ebselen protects mitochondrial function and oxidative stress while inhibiting the mitochondrial apoptosis pathway after acute spinal cord injury.

PubMed

Jia, Zhi-Qiang; Li, San-Qiang; Qiao, Wei-Qiang; Xu, Wen-Zhong; Xing, Jian-Wu; Liu, Jian-Tao; Song, Hui; Gao, Zhong-Yang; Xing, Bing-Wen; He, Xi-Jing

2018-05-04

Ebselen is a fat-soluble small molecule and organic selenium compound that regulates the activity of glutathione peroxidase to alleviate mitochondrial oxidative stress and improve mitochondrial function. In the present study, we aimed to investigate the effects of ebselen on mitochondrial oxidative stress response, mitochondrial apotosis, and motor behaviors after spinal cord injury (SCI). We found that ebselen significantly increased the BBB score in motor behavior, thus suggesting a rescue effect of ebselen on motor function after SCI in rats. Meanwhile, we revealed that ebselen can increase glutathione (GSH) content as well as superoxide dismutase (SOD) and catalase (CAT) activities after SCI-this suggests ebselen has an antioxidant effect. Furthermore, the ATP content and Na + -K + -ATPase activity in mitochondria were increased by ebselen after SCI, while the mitochondrial membrane potential (MMP) was decreased by ebselen. The Cytochrome C and Smac release from mitochondria were reduced by ebselen after SCI, thus indicating improved membrane permeability by ebselen. Moreover, the alterations in caspase-3, Bax and Bcl-2 protein expression, as well as the proportion of cell apoptosis were improved by ebselen treatment, which together suggested that ebselen has an inhibitory effect on mitochondrial apotosis pathways after SCI. Taken together, our results suggest that ebselen can inhibit secondary damage caused by spinal cord injury. Indeed it plays a neuroprotective role in spinal cord injury perhaps by improving mitochondrial function and inhibiting the mitochondrial apoptosis pathway. Copyright © 2018 Elsevier B.V. All rights reserved.

Staphylococcus aureus Sepsis Induces Early Renal Mitochondrial DNA Repair and Mitochondrial Biogenesis in Mice

PubMed Central

Bartz, Raquel R.; Fu, Ping; Suliman, Hagir B.; Crowley, Stephen D.; MacGarvey, Nancy Chou; Welty-Wolf, Karen; Piantadosi, Claude A.

2014-01-01

Acute kidney injury (AKI) contributes to the high morbidity and mortality of multi-system organ failure in sepsis. However, recovery of renal function after sepsis-induced AKI suggests active repair of energy-producing pathways. Here, we tested the hypothesis in mice that Staphyloccocus aureus sepsis damages mitochondrial DNA (mtDNA) in the kidney and activates mtDNA repair and mitochondrial biogenesis. Sepsis was induced in wild-type C57Bl/6J and Cox-8 Gfp-tagged mitochondrial-reporter mice via intraperitoneal fibrin clots embedded with S. aureus. Kidneys from surviving mice were harvested at time zero (control), 24, or 48 hours after infection and evaluated for renal inflammation, oxidative stress markers, mtDNA content, and mitochondrial biogenesis markers, and OGG1 and UDG mitochondrial DNA repair enzymes. We examined the kidneys of the mitochondrial reporter mice for changes in staining density and distribution. S. aureus sepsis induced sharp amplification of renal Tnf, Il-10, and Ngal mRNAs with decreased renal mtDNA content and increased tubular and glomerular cell death and accumulation of protein carbonyls and 8-OHdG. Subsequently, mtDNA repair and mitochondrial biogenesis was evidenced by elevated OGG1 levels and significant increases in NRF-1, NRF-2, and mtTFA expression. Overall, renal mitochondrial mass, tracked by citrate synthase mRNA and protein, increased in parallel with changes in mitochondrial GFP-fluorescence especially in proximal tubules in the renal cortex and medulla. Sub-lethal S. aureus sepsis thus induces widespread renal mitochondrial damage that triggers the induction of the renal mtDNA repair protein, OGG1, and mitochondrial biogenesis as a conspicuous resolution mechanism after systemic bacterial infection. PMID:24988481

Mitochondrial dysfunction and organophosphorus compounds

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

Karami-Mohajeri, Somayyeh; Department of Toxicology and Pharmacology, Faculty of Pharmacy, and Pharmaceutical Sciences Research Center, Kerman University of Medical Sciences, Kerman; Abdollahi, Mohammad, E-mail: Mohammad.Abdollahi@UToronto.Ca

2013-07-01

Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen frommore » dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP.« less

Mitochondrial Reactive Oxygen Species and Kidney Hypoxia in the Development of Diabetic Nephropathy

PubMed Central

Schiffer, Tomas A.; Friederich-Persson, Malou

2017-01-01

The underlying mechanisms in the development of diabetic nephropathy are currently unclear and likely consist of a series of dynamic events from the early to late stages of the disease. Diabetic nephropathy is currently without curative treatments and it is acknowledged that even the earliest clinical manifestation of nephropathy is preceded by an established morphological renal injury that is in turn preceded by functional and metabolic alterations. An early manifestation of the diabetic kidney is the development of kidney hypoxia that has been acknowledged as a common pathway to nephropathy. There have been reports of altered mitochondrial function in the diabetic kidney such as altered mitophagy, mitochondrial dynamics, uncoupling, and cellular signaling through hypoxia inducible factors and AMP-kinase. These factors are also likely to be intertwined in a complex manner. In this review, we discuss how these pathways are connected to mitochondrial production of reactive oxygen species (ROS) and how they may relate to the development of kidney hypoxia in diabetic nephropathy. From available literature, it is evident that early correction and/or prevention of mitochondrial dysfunction may be pivotal in the prevention and treatment of diabetic nephropathy. PMID:28443030

Mitochondrial Reactive Oxygen Species and Kidney Hypoxia in the Development of Diabetic Nephropathy.

PubMed

Schiffer, Tomas A; Friederich-Persson, Malou

2017-01-01

The underlying mechanisms in the development of diabetic nephropathy are currently unclear and likely consist of a series of dynamic events from the early to late stages of the disease. Diabetic nephropathy is currently without curative treatments and it is acknowledged that even the earliest clinical manifestation of nephropathy is preceded by an established morphological renal injury that is in turn preceded by functional and metabolic alterations. An early manifestation of the diabetic kidney is the development of kidney hypoxia that has been acknowledged as a common pathway to nephropathy. There have been reports of altered mitochondrial function in the diabetic kidney such as altered mitophagy, mitochondrial dynamics, uncoupling, and cellular signaling through hypoxia inducible factors and AMP-kinase. These factors are also likely to be intertwined in a complex manner. In this review, we discuss how these pathways are connected to mitochondrial production of reactive oxygen species (ROS) and how they may relate to the development of kidney hypoxia in diabetic nephropathy. From available literature, it is evident that early correction and/or prevention of mitochondrial dysfunction may be pivotal in the prevention and treatment of diabetic nephropathy.

Effects of mitochondrial poisons on glutathione redox potential and carotid body chemoreceptor activity.

PubMed

Gomez-Niño, A; Agapito, M T; Obeso, A; Gonzalez, C

2009-01-01

Low oxygen sensing in chemoreceptor cells involves the inhibition of specific plasma membrane K(+) channels, suggesting that mitochondria-derived reactive oxygen species (ROS) link hypoxia to K(+) channel inhibition, subsequent cell depolarization and activation of neurotransmitter release. We have used several mitochondrial poisons, alone and in combination with the antioxidant N-acetylcysteine (NAC), and quantify their capacity to alter GSH/GSSG levels and glutathione redox potential (E(GSH)) in rat diaphragm. Selected concentrations of mitochondrial poisons with or without NAC were tested for their capacity to activate neurotransmitter release in chemoreceptor cells and to alter ATP levels in intact rat carotid body (CB). We found that rotenone (1 microM), antimycin A (0.2 microg/ml) and sodium azide (5mM) decreased E(GSH); NAC restored E(GSH) to control values. At those concentrations mitochondrial poisons activated neurotransmitter release from CB chemoreceptor cells and decreased CB ATP levels, NAC being ineffective to modify these responses. Additional experiments with 3-nitroprionate (5mM), lower concentrations of rotenone and dinitrophenol revealed variable relationships between E(GSH) and chemoreceptor cell neurotransmitter release responses and ATP levels. These findings indicate a lack of correlation between mitochondrial-generated modifications of E(GSH) and chemoreceptor cells activity. This lack of correlation renders unlikely that alteration of mitochondrial production of ROS is the physiological pathway chemoreceptor cells use to signal hypoxia.

Electrophysiological, haemodynamic, and mitochondrial alterations induced by levobupivacaine during myocardial ischemia in a pig model: protection by lipid emulsions?

PubMed

Mamou, Zahida; Descotes, Jacques; Chevalier, Philippe; Bui-Xuan, Bernard; Romestaing, Caroline; Timour, Quadiri

2015-10-01

Accidental intravascular or high-dose injection of local anesthetics (LA) can result in serious, potentially life-threatening complications. Indeed, adequate supportive measures and the administration of lipid emulsions are required in such complications. The study's objectives were threefold: (i) evaluate the myocardial toxicity of levobupivacaine when administered intravenously; (ii) investigate levobupivacaine toxicity on cardiomyocytes mitochondrial functions and cellular structure; (iii) assess the protective effects of a lipid emulsion in the presence or absence of myocardial ischemia. Domestic pigs randomized into two groups of 24 animals each, with either preserved coronary circulation or experimental myocardial ischemia. Six animals from each group received either: (i) single IV injection of saline, (ii) lipid emulsion (Intralipid(®) ), (iii) levobupivacaine, (iv) combination levobupivacaine-Intralipid(®) . Serially measured endpoints included: heart rate, duration of the monophasic action potentials (dMAP), mean arterial pressure, and peak of the time derivative of left ventricular pressure (LV dP/dtmax ). In addition, the following cardiomyocytes mitochondrial functions were measured: reactive oxygen species (ROS) production, oxidative phosphorylation, and calcium retention capacity (CRC) as well as the consequences of ROS production on lipids, proteins, and DNA. IV injection of levobupivacaine induced sinus bradycardia and reduced dMAP and LV dP/dtmax . At the mitochondrial level, oxygen consumption and CRC were decreased. In contrast, ROS production was increased leading to enhanced lipid peroxidation and structural alterations of proteins and DNA. Myocardial ischemia was associated with global worsening of all changes. Intralipid(®) quickly improved haemodynamics. However, beneficial effects of Intralipid(®) were less clear after myocardial ischemia. © 2015 Société Française de Pharmacologie et de Thérapeutique.

Acute maneb exposure significantly alters both glycolysis and mitochondrial function in neuroblastoma cells.

PubMed

Anderson, Colin C; Aivazidis, Stefanos; Kuzyk, Crystal L; Jain, Abhilasha; Roede, James R

2018-05-14

The pesticides paraquat (PQ) and maneb (MB) have been described as environmental risk factors for Parkinson's disease (PD), with mechanisms associated with mitochondrial dysfunction and reactive oxygen species (ROS) generation. A combined exposure of PQ and MB in murine models and neuroblastoma cells has been utilized to further advance understanding of the PD phenotype. MB acts as a redox modulator through alkylation of protein thiols and has been previously characterized to inhibit complex III of the electron transport chain (ETC) and uncouple the mitochondrial proton gradient. The purpose of this study was to analyze ATP-linked respiration and glycolysis in human neuroblastoma cells utilizing the Seahorse extracellular flux (XFp) platform. Employing an acute, subtoxic exposure of MB, this investigation revealed a MB-mediated decrease in mitochondrial oxygen consumption at baseline and maximal respiration, with inhibition of ATP synthesis and coupling efficiency. Additionally, MB treated cells showed an increase in non-mitochondrial respiration and proton leak. Further investigation into mitochondrial fuel flex revealed an elimination of fuel flexibility across all three major substrates, with a decrease in pyruvate capacity as well as glutamine dependency. Analyses of glycolytic function showed a substantial decrease in glycolytic acidification caused by lactic acid export. This inhibition of glycolytic parameters was also observed after titrating the MB dose as low as 6 μM, and appears to be dependent on the dithiocarbamate functional group, with manganese possibly potentiating the effect. Further studies into cellular ATP and NAD levels revealed a drastic decrease in cells treated with MB. In summary, MB significantly impacted both aerobic and anaerobic energy production; therefore, further characterization of MB's effect on cellular energetics may provide insight into the specificity of PD to dopaminergic neurons.

Mitochondrial remodeling in the liver following chronic alcohol feeding to rats.

PubMed

Han, Derick; Johnson, Heather S; Rao, Madhuri P; Martin, Gary; Sancheti, Harsh; Silkwood, Kai H; Decker, Carl W; Nguyen, Kim Tho; Casian, Joseph G; Cadenas, Enrique; Kaplowitz, Neil

2017-01-01

The feeding of alcohol orally (Lieber-DeCarli diet) to rats has been shown to cause declines in mitochondrial respiration (state III), decreased expression of respiratory complexes, and decreased respiratory control ratios (RCR) in liver mitochondria. These declines and other mitochondrial alterations have led to the hypothesis that alcohol feeding causes "mitochondrial dysfunction" in the liver. If oral alcohol feeding leads to mitochondrial dysfunction, one would predict that increasing alcohol delivery by intragastric (IG) alcohol feeding to rats would cause greater declines in mitochondrial bioenergetics in the liver. In this study, we examined the mitochondrial alterations that occur in rats fed alcohol both orally and intragastrically. Oral alcohol feeding decreased glutamate/malate-, acetaldehyde- and succinate-driven state III respiration, RCR, and expression of respiratory complexes (I, III, IV, V) in liver mitochondria, in agreement with previous results. IG alcohol feeding, on the other hand, caused a slight increase in glutamate/malate-driven respiration, and significantly increased acetaldehyde-driven respiration in liver mitochondria. IG feeding also caused liver mitochondria to experience a decline in succinate-driven respiration, but these decreases were smaller than those observed with oral alcohol feeding. Surprisingly, oral and IG alcohol feeding to rats increased mitochondrial respiration using other substrates, including glycerol-3-phosphate (which delivers electrons from cytoplasmic NADH to mitochondria) and octanoate (a substrate for beta-oxidation). The enhancement of glycerol-3-phosphate- and octanoate-driven respiration suggests that liver mitochondria remodeled in response to alcohol feeding. In support of this notion, we observed that IG alcohol feeding also increased expression of mitochondrial glycerol phosphate dehydrogenase-2 (GPD2), transcription factor A (TFAM), and increased mitochondrial NAD + -NADH and NADP + -NADPH levels in

Mitochondrial Dysfunction in Lysosomal Storage Disorders

PubMed Central

de la Mata, Mario; Cotán, David; Villanueva-Paz, Marina; de Lavera, Isabel; Álvarez-Córdoba, Mónica; Luzón-Hidalgo, Raquel; Suárez-Rivero, Juan M.; Tiscornia, Gustavo; Oropesa-Ávila, Manuel

2016-01-01

Lysosomal storage diseases (LSDs) describe a heterogeneous group of rare inherited metabolic disorders that result from the absence or loss of function of lysosomal hydrolases or transporters, resulting in the progressive accumulation of undigested material in lysosomes. The accumulation of substances affects the function of lysosomes and other organelles, resulting in secondary alterations such as impairment of autophagy, mitochondrial dysfunction, inflammation and apoptosis. LSDs frequently involve the central nervous system (CNS), where neuronal dysfunction or loss results in progressive neurodegeneration and premature death. Many LSDs exhibit signs of mitochondrial dysfunction, which include mitochondrial morphological changes, decreased mitochondrial membrane potential (ΔΨm), diminished ATP production and increased generation of reactive oxygen species (ROS). Furthermore, reduced autophagic flux may lead to the persistence of dysfunctional mitochondria. Gaucher disease (GD), the LSD with the highest prevalence, is caused by mutations in the GBA1 gene that results in defective and insufficient activity of the enzyme β-glucocerebrosidase (GCase). Decreased catalytic activity and/or instability of GCase leads to accumulation of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph) in the lysosomes of macrophage cells and visceral organs. Mitochondrial dysfunction has been reported to occur in numerous cellular and mouse models of GD. The aim of this manuscript is to review the current knowledge and implications of mitochondrial dysfunction in LSDs. PMID:28933411

Nucleotide pools dictate the identity and frequency of ribonucleotide incorporation in mitochondrial DNA.

PubMed

Berglund, Anna-Karin; Navarrete, Clara; Engqvist, Martin K M; Hoberg, Emily; Szilagyi, Zsolt; Taylor, Robert W; Gustafsson, Claes M; Falkenberg, Maria; Clausen, Anders R

2017-02-01

Previous work has demonstrated the presence of ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated ribonucleotides reflect that DNA polymerase γ discriminates the four ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyribonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of ribonucleotides in mtDNA and argues against the existence of a mitochondrial ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, ribonucleotides serve as a source of building blocks to maintain DNA replication. Increased levels of embedded ribonucleotides in patient cells with disturbed nucleotide pools may contribute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication.

Nucleotide pools dictate the identity and frequency of ribonucleotide incorporation in mitochondrial DNA

PubMed Central

Hoberg, Emily; Szilagyi, Zsolt; Taylor, Robert W.; Gustafsson, Claes M.; Falkenberg, Maria

2017-01-01

Previous work has demonstrated the presence of ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated ribonucleotides reflect that DNA polymerase γ discriminates the four ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyribonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of ribonucleotides in mtDNA and argues against the existence of a mitochondrial ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, ribonucleotides serve as a source of building blocks to maintain DNA replication. Increased levels of embedded ribonucleotides in patient cells with disturbed nucleotide pools may contribute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication. PMID:28207748

Alterations of mitochondrial DNA in CEM cells selected for resistance toward ddC toxicity.

PubMed

Bjerke, M; Franco, M; Johansson, M; Balzarini, J; Karlsson, A

2006-01-01

2 ',3 '-dideoxycytidine (ddC) is a nucleoside analog that has been shown to produce a delayed toxicity which may be due to the depletion of mitochondrial DNA (mtDNA). In order to gain further understanding of the events involved in mitochondrial toxicity, two different CEM cell lines were selected for resistance to the delayed ddC toxicity.

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

A Functional Antagonistic Relationship between Auxin and Mitochondrial Retrograde Signaling Regulates Alternative Oxidase1a Expression in Arabidopsis1[W][OPEN

PubMed Central

Ivanova, Aneta; Law, Simon R.; Narsai, Reena; Duncan, Owen; Lee, Jae-Hoon; Zhang, Botao; Van Aken, Olivier; Radomiljac, Jordan D.; van der Merwe, Margaretha; Yi, KeKe; Whelan, James

2014-01-01

The perception and integration of stress stimuli with that of mitochondrion function are important during periods of perturbed cellular homeostasis. In a continuous effort to delineate these mitochondrial/stress-interacting networks, forward genetic screens using the mitochondrial stress response marker alternative oxidase 1a (AOX1a) provide a useful molecular tool to identify and characterize regulators of mitochondrial stress signaling (referred to as regulators of alternative oxidase 1a [RAOs] components). In this study, we reveal that mutations in genes coding for proteins associated with auxin transport and distribution resulted in a greater induction of AOX1a in terms of magnitude and longevity. Three independent mutants for polarized auxin transport, rao3/big, rao4/pin-formed1, and rao5/multidrug-resistance1/abcb19, as well as the Myb transcription factor rao6/asymmetric leaves1 (that displays altered auxin patterns) were identified and resulted in an acute sensitivity toward mitochondrial dysfunction. Induction of the AOX1a reporter system could be inhibited by the application of auxin analogs or reciprocally potentiated by blocking auxin transport. Promoter activation studies with AOX1a::GUS and DR5::GUS lines further confirmed a clear antagonistic relationship between the spatial distribution of mitochondrial stress and auxin response kinetics, respectively. Genome-wide transcriptome analyses revealed that mitochondrial stress stimuli, such as antimycin A, caused a transient suppression of auxin signaling and conversely, that auxin treatment repressed a part of the response to antimycin A treatment, including AOX1a induction. We conclude that mitochondrial stress signaling and auxin signaling are reciprocally regulated, balancing growth and stress response(s). PMID:24820025

Mitochondrial dysfunction and sarcopenia of aging: from signaling pathways to clinical trials

PubMed Central

Marzetti, Emanuele; Calvani, Riccardo; Cesari, Matteo; Buford, Thomas W.; Lorenzi, Maria; Behnke, Bradley J.; Leeuwenburgh, Christiaan

2013-01-01

Sarcopenia, the age-related loss of muscle mass and function, imposes a dramatic burden on individuals and society. The development of preventive and therapeutic strategies against sarcopenia is therefore perceived as an urgent need by health professionals and has instigated intensive research on the pathophysiology of this syndrome. The pathogenesis of sarcopenia is multifaceted and encompasses lifestyle habits, systemic factors (e.g., chronic inflammation and hormonal alterations), local environment perturbations (e.g., vascular dysfunction), and intramuscular specific processes. In this scenario, derangements in skeletal myocyte mitochondrial function are recognized as major factors contributing to the age-dependent muscle degeneration. In this review, we summarize prominent findings and controversial issues on the contribution of specific mitochondrial processes – including oxidative stress, quality control mechanisms and apoptotic signaling – on the development of sarcopenia. Extramuscular alterations accompanying the aging process with a potential impact on myocyte mitochondrial function are also discussed. We conclude with presenting methodological and safety considerations for the design of clinical trials targeting mitochondrial dysfunction to treat sarcopenia. Special emphasis is placed on the importance of monitoring the effects of an intervention on muscle mitochondrial function and identifying the optimal target population for the trial. PMID:23845738

Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

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

Sirvent, P., E-mail: pascal.sirvent@univ-bpclermont.fr; CHRU Montpellier, 34295 Montpellier; Clermont Université, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques

2012-03-01

The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complexmore » I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro. -- Highlights: ► The most common and problematic side effect of statins is myopathy. ► Patients treated with statins showed impairment of mitochondrial respiration. ► Statins-treated patients showed altered frequency and amplitude of calcium sparks.« less

Mitochondrial protein hyperacetylation in the failing heart.

PubMed

Horton, Julie L; Martin, Ola J; Lai, Ling; Riley, Nicholas M; Richards, Alicia L; Vega, Rick B; Leone, Teresa C; Pagliarini, David J; Muoio, Deborah M; Bedi, Kenneth C; Margulies, Kenneth B; Coon, Joshua J; Kelly, Daniel P

2016-02-01

Myocardial fuel and energy metabolic derangements contribute to the pathogenesis of heart failure. Recent evidence implicates posttranslational mechanisms in the energy metabolic disturbances that contribute to the pathogenesis of heart failure. We hypothesized that accumulation of metabolite intermediates of fuel oxidation pathways drives posttranslational modifications of mitochondrial proteins during the development of heart failure. Myocardial acetylproteomics demonstrated extensive mitochondrial protein lysine hyperacetylation in the early stages of heart failure in well-defined mouse models and the in end-stage failing human heart. To determine the functional impact of increased mitochondrial protein acetylation, we focused on succinate dehydrogenase A (SDHA), a critical component of both the tricarboxylic acid (TCA) cycle and respiratory complex II. An acetyl-mimetic mutation targeting an SDHA lysine residue shown to be hyperacetylated in the failing human heart reduced catalytic function and reduced complex II-driven respiration. These results identify alterations in mitochondrial acetyl-CoA homeostasis as a potential driver of the development of energy metabolic derangements that contribute to heart failure.

Two copies of mthmg1, encoding a novel mitochondrial HMG-like protein, delay accumulation of mitochondrial DNA deletions in Podospora anserina.

PubMed

Dequard-Chablat, Michelle; Allandt, Cynthia

2002-08-01

In the filamentous fungus Podospora anserina, two degenerative processes which result in growth arrest are associated with mitochondrial genome (mitochondrial DNA [mtDNA]) instability. Senescence is correlated with mtDNA rearrangements and amplification of specific regions (senDNAs). Premature death syndrome is characterized by the accumulation of specific mtDNA deletions. This accumulation is due to indirect effects of the AS1-4 mutation, which alters a cytosolic ribosomal protein gene. The mthmg1 gene has been identified as a double-copy suppressor of premature death. It greatly delays premature death and the accumulation of deletions when it is present in two copies in an ASI-4 context. The duplication of mthmg1 has no significant effect on the wild-type life span or on senDNA patterns. In anAS1+ context, deletion of the mthmg1 gene alters germination, growth, and fertility and reduces the life span. The deltamthmg1 senescent strains display a particular senDNA pattern. This deletion is lethal in an AS1-4 context. According to its physical properties (very basic protein with putative mitochondrial targeting sequence and HMG-type DNA-binding domains) and the cellular localization of an mtHMG1-green fluorescent protein fusion, mtHMG1 appears to be a mitochondrial protein possibly associated with mtDNA. It is noteworthy that it is the first example of a protein combining the two DNA-binding domains, AT-hook motif and HMG-1 boxes. It may be involved in the stability and/or transmission of the mitochondrial genome. To date, no structural homologues have been found in other organisms. However, mtHMG1 displays functional similarities with the Saccharomyces cerevisiae mitochondrial HMG-box protein Abf2.

Lipopolysaccharide-induced mitochondrial dysfunction in boar sperm is mediated by activation of oxidative phosphorylation.

PubMed

He, Bin; Guo, Huiduo; Gong, Yabin; Zhao, Ruqian

2017-01-01

Lipopolysaccharide (LPS) has been reported to exert detrimental effects on boar sperm viability. In the present study, LPS was detected in boar semen samples at an average level of 0.62 ± 0.14 μg/mL. We treated boar sperm with 1 μg/mL LPS for 6 hours and examined alterations in sperm motility and apoptosis, together with mitochondrial functionality and mitochondrial reactive oxygen species generation. The expression and the location of toll-like receptor 4 (TLR4) and mitochondrial transcription factor A (TFAM) were determined to reveal possible mechanisms. LPS-treated sperm showed significant reduction in motility (P < 0.05) and viability (P < 0.05). LPS induced sperm mitochondrial damage via oxidative stress which is indicated by marked ultrastructural changes in the mitochondria including swelling, disorientation and vacuole, a decrease of mitochondrial membrane potential (ΔΨm; P < 0.05), as well as an increase of malondialdehyde levels (P < 0.01). Moreover, the production of mitochondrial reactive oxygen species through oxidative phosphorylation (OXPHOS) was significantly (P < 0.05) increased, which leads to oxidative stress. The copy number of mitochondrial DNA was significantly (P < 0.05) higher in LPS-treated sperm. Moreover, cytochrome c oxidase subunit IV (COXIV), an important subunit in mitochondrial electron transport chain and OXPHOS, was significantly (P < 0.05) upregulated after LPS treatment. TFAM, the key transcription factor that activates mitochondrial DNA replication and transcription, was translocated from the head to the midpiece of sperm where mitochondria are distributed in LPS-treated sperm. Taken together, these results indicate that LPS-induced decrease of motility and viability in boar sperm is mediated by abnormal activation of OXPHOS and mitochondrial membrane lipid peroxidation. These findings may provide new insights in understanding the mechanisms underlying the bacterial infection-induced sperm damage

Cold and Heat Stress Diversely Alter Both Cauliflower Respiration and Distinct Mitochondrial Proteins Including OXPHOS Components and Matrix Enzymes

PubMed Central

Rurek, Michał; Czołpińska, Magdalena; Pawłowski, Tomasz Andrzej; Krzesiński, Włodzimierz; Spiżewski, Tomasz

2018-01-01

Complex proteomic and physiological approaches for studying cold and heat stress responses in plant mitochondria are still limited. Variations in the mitochondrial proteome of cauliflower (Brassica oleracea var. botrytis) curds after cold and heat and after stress recovery were assayed by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) in relation to mRNA abundance and respiratory parameters. Quantitative analysis of the mitochondrial proteome revealed numerous stress-affected protein spots. In cold, major downregulations in the level of photorespiratory enzymes, porine isoforms, oxidative phosphorylation (OXPHOS) and some low-abundant proteins were observed. In contrast, carbohydrate metabolism enzymes, heat-shock proteins, translation, protein import, and OXPHOS components were involved in heat response and recovery. Several transcriptomic and metabolic regulation mechanisms are also suggested. Cauliflower plants appeared less susceptible to heat; closed stomata in heat stress resulted in moderate photosynthetic, but only minor respiratory impairments, however, photosystem II performance was unaffected. Decreased photorespiration corresponded with proteomic alterations in cold. Our results show that cold and heat stress not only operate in diverse modes (exemplified by cold-specific accumulation of some heat shock proteins), but exert some associations at molecular and physiological levels. This implies a more complex model of action of investigated stresses on plant mitochondria. PMID:29547512

Mitochondrial DNA 3243A>G heteroplasmy is associated with changes in cytoskeletal protein expression and cell mechanics.

PubMed

Kandel, Judith; Picard, Martin; Wallace, Douglas C; Eckmann, David M

2017-06-01

Mitochondrial and mechanical alterations in cells have both been shown to be hallmarks of human disease. However, little research has endeavoured to establish connections between these two essential features of cells in both functional and dysfunctional situations. In this work, we hypothesized that a specific genetic alteration in mitochondrial function known to cause human disease would trigger changes in cell mechanics. Using a previously characterized set of mitochondrial cybrid cell lines, we examined the relationship between heteroplasmy for the mitochondrial DNA (mtDNA) 3243A>G mutation, the cell cytoskeleton, and resulting cellular mechanical properties. We found that cells with increasing mitochondrial dysfunction markedly differed from one another in gene expression and protein production of various co-regulated cytoskeletal elements. The intracellular positioning and organization of actin also differed across cell lines. To explore the relationship between these changes and cell mechanics, we then measured cellular mechanical properties using atomic force microscopy and found that cell stiffness correlated with gene expression data for known determinants of cell mechanics, γ-actin, α-actinin and filamin A. This work points towards a mechanism linking mitochondrial genetics to single-cell mechanical properties. The transcriptional and structural regulation of cytoskeletal components by mitochondrial function may explain why energetic and mechanical alterations often coexist in clinical conditions. © 2017 The Author(s).

Mutations in FBXL4 Cause Mitochondrial Encephalopathy and a Disorder of Mitochondrial DNA Maintenance

PubMed Central

Bonnen, Penelope E.; Yarham, John W.; Besse, Arnaud; Wu, Ping; Faqeih, Eissa A.; Al-Asmari, Ali Mohammad; Saleh, Mohammad A.M.; Eyaid, Wafaa; Hadeel, Alrukban; He, Langping; Smith, Frances; Yau, Shu; Simcox, Eve M.; Miwa, Satomi; Donti, Taraka; Abu-Amero, Khaled K.; Wong, Lee-Jun; Craigen, William J.; Graham, Brett H.; Scott, Kenneth L.; McFarland, Robert; Taylor, Robert W.

2013-01-01

Nuclear genetic disorders causing mitochondrial DNA (mtDNA) depletion are clinically and genetically heterogeneous, and the molecular etiology remains undiagnosed in the majority of cases. Through whole-exome sequencing, we identified recessive nonsense and splicing mutations in FBXL4 segregating in three unrelated consanguineous kindreds in which affected children present with a fatal encephalopathy, lactic acidosis, and severe mtDNA depletion in muscle. We show that FBXL4 is an F-box protein that colocalizes with mitochondria and that loss-of-function and splice mutations in this protein result in a severe respiratory chain deficiency, loss of mitochondrial membrane potential, and a disturbance of the dynamic mitochondrial network and nucleoid distribution in fibroblasts from affected individuals. Expression of the wild-type FBXL4 transcript in cell lines from two subjects fully rescued the levels of mtDNA copy number, leading to a correction of the mitochondrial biochemical deficit. Together our data demonstrate that mutations in FBXL4 are disease causing and establish FBXL4 as a mitochondrial protein with a possible role in maintaining mtDNA integrity and stability. PMID:23993193

Alterations in mitochondrial dynamics induced by tebufenpyrad and pyridaben in a dopaminergic neuronal cell culture model

PubMed Central

Charli, Adhithiya; Jin, Huajun; Anantharam, Vellareddy; Kanthasamy, Arthi; Kanthasamy, Anumantha G.

2015-01-01

Tebufenpyrad and pyridaben are two agro-chemically important acaricides that function like the known mitochondrial toxicant rotenone. Although these two compounds have been commonly used to kill populations of mites and ticks in commercial greenhouses, their neurotoxic profiles remain largely unknown. Therefore, we investigated the effects of these two pesticides on mitochondrial structure and function in an in vitro cell culture model using the Seahorse bioanalyzer and confocal fluorescence imaging. The effects were compared with rotenone. Exposing rat dopaminergic neuronal cells (N27 cells) to tebufenpyrad and pyridaben for 3 h induced dose-dependent cell death with an EC50 of 3.98 μM and 3.77 μM, respectively. Also, tebufenpyrad and pyridaben (3 μM) exposure induced reactive oxygen species (ROS) generation and m-aconitase damage, suggesting that the pesticide toxicity is associated with oxidative damage. Morphometric image analysis with the MitoTracker red fluorescent probe indicated that tebufenpyrad and pyridaben, as well as rotenone, caused abnormalities in mitochondrial morphology, including reduced mitochondrial length and circularity. Functional bioenergetic experiments using the Seahorse XF96 analyzer revealed that tebufenpyrad and pyridaben very rapidly suppressed the basal mitochondrial oxygen consumption rate similar to that of rotenone. Further analysis of bioenergetic curves also revealed dose-dependent decreases in ATP-linked respiration and respiratory capacity. The luminescence-based ATP measurement further confirmed that pesticide-induced mitochondrial inhibition of respiration is accompanied by the loss of cellular ATP. Collectively, our results suggest that exposure to the pesticides tebufenpyrad and pyridaben induces neurotoxicity by rapidly initiating mitochondrial dysfunction and oxidative damage in dopaminergic neuronal cells. Our findings also reveal that monitoring the kinetics of mitochondrial respiration with Seahorse could be used

Evolutionary divergence of mitochondrial genomes in two Tetranychus species distributed across different climates.

PubMed

Sun, J-T; Jin, P-Y; Hoffmann, A A; Duan, X-Z; Dai, J; Hu, G; Xue, X-F; Hong, X-Y

2018-05-24

There is increasing evidence that mitochondrial genomes (mitogenomes) can be under selection, whereas the selective regimes shaping mitogenome evolution remain largely unclear. To test for mitochondrial genome evolution in relation to the climate adaptation, we explored mtDNA variation in two spider mite (Tetranychus) species, which distribute across different climates. We sequenced 26 complete mitogenomes of T. truncatus which occurs in both warm and cold regions, and 9 complete mitogenomes of T. pueraricola which is only restricted in warm regions. Patterns of evolution in the two species mitogenomes were compared through a series of d N /d S methods and physicochemical profiles of amino acid replacements. We found that (1) the mitogenomes of both species were under widespread purifying selection. (2) Elevated directional adaptive selection was observed in the T. truncatus mitogenome, perhaps linked to the cold climates adaptation of T. truncatus. (3) The strength of selection varied across genes, and diversifying positive selection detected on ND4 and ATP6 pointed to their crucial roles during adaptation to different climatic conditions. This study gained insight into the mitogenome evolution in relation to the climate adaptation. This article is protected by copyright. All rights reserved. © 2018 The Royal Entomological Society.

CoMIC, the hidden dynamics of mitochondrial inner compartments

PubMed Central

Cho, Bongki; Sun, Woong

2017-01-01

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, Constriction of Mitochondrial Inner Compartment. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division. PMID:28803609

CoMIC, the hidden dynamics of mitochondrial inner compartments.

PubMed

Cho, Bongki; Sun, Woong

2017-12-01

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, Constriction of Mitochondrial Inner Compartment. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division. [BMB Reports 2017; 50(12): 597-598].

Alterations of motor performance and brain cortex mitochondrial function during ethanol hangover.

PubMed

Bustamante, Juanita; Karadayian, Analia G; Lores-Arnaiz, Silvia; Cutrera, Rodolfo A

2012-08-01

Ethanol has been known to affect various behavioral parameters in experimental animals, even several hours after ethanol (EtOH) is absent from blood circulation, in the period known as hangover. The aim of this study was to assess the effects of acute ethanol hangover on motor performance in association with the brain cortex energetic metabolism. Evaluation of motor performance and brain cortex mitochondrial function during alcohol hangover was performed in mice 6 hours after a high ethanol dose (hangover onset). Animals were injected i.p. either with saline (control group) or with ethanol (3.8 g/kg BW) (hangover group). Ethanol hangover group showed a bad motor performance compared with control animals (p < .05). Oxygen uptake in brain cortex mitochondria from hangover animals showed a 34% decrease in the respiratory control rate as compared with the control group. Mitochondrial complex activities were decreased being the complex I-III the less affected by the hangover condition; complex II-III was markedly decreased by ethanol hangover showing 50% less activity than controls. Complex IV was 42% decreased as compared with control animals. Hydrogen peroxide production was 51% increased in brain cortex mitochondria from the hangover group, as compared with the control animals. Quantification of the mitochondrial transmembrane potential indicated that ethanol injected animals presented 17% less ability to maintain the polarized condition as compared with controls. These results indicate that a clear decrease in proton motive force occurs in brain cortex mitochondria during hangover conditions. We can conclude that a decreased motor performance observed in the hangover group of animals could be associated with brain cortex mitochondrial dysfunction and the resulting impairment of its energetic metabolism. Copyright © 2012 Elsevier Inc. All rights reserved.

Therapeutically targeting mitochondrial redox signalling alleviates endothelial dysfunction in preeclampsia.

PubMed

McCarthy, Cathal; Kenny, Louise C

2016-09-08

Aberrant placentation generating placental oxidative stress is proposed to play a critical role in the pathophysiology of preeclampsia. Unfortunately, therapeutic trials of antioxidants have been uniformly disappointing. There is provisional evidence implicating mitochondrial dysfunction as a source of oxidative stress in preeclampsia. Here we provide evidence that mitochondrial reactive oxygen species mediates endothelial dysfunction and establish that directly targeting mitochondrial scavenging may provide a protective role. Human umbilical vein endothelial cells exposed to 3% plasma from women with pregnancies complicated by preeclampsia resulted in a significant decrease in mitochondrial function with a subsequent significant increase in mitochondrial superoxide generation compared to cells exposed to plasma from women with uncomplicated pregnancies. Real-time PCR analysis showed increased expression of inflammatory markers TNF-α, TLR-9 and ICAM-1 respectively in endothelial cells treated with preeclampsia plasma. MitoTempo is a mitochondrial-targeted antioxidant, pre-treatment of cells with MitoTempo protected against hydrogen peroxide-induced cell death. Furthermore MitoTempo significantly reduced mitochondrial superoxide production in cells exposed to preeclampsia plasma by normalising mitochondrial metabolism. MitoTempo significantly altered the inflammatory profile of plasma treated cells. These novel data support a functional role for mitochondrial redox signaling in modulating the pathogenesis of preeclampsia and identifies mitochondrial-targeted antioxidants as potential therapeutic candidates.

Alterations to mitochondrial fatty-acid use in skeletal muscle after chronic exposure to hypoxia depend on metabolic phenotype.

PubMed

Malgoyre, Alexandra; Chabert, Clovis; Tonini, Julia; Koulmann, Nathalie; Bigard, Xavier; Sanchez, Hervé

2017-03-01

We investigated the effects of chronic hypoxia on the maximal use of and sensitivity of mitochondria to different substrates in rat slow-oxidative (soleus, SOL) and fast-glycolytic (extensor digitorum longus, EDL) muscles. We studied mitochondrial respiration in situ in permeabilized myofibers, using pyruvate, octanoate, palmitoyl-carnitine (PC), or palmitoyl-coenzyme A (PCoA). The hypophagia induced by hypoxia may also alter metabolism. Therefore, we used a group of pair-fed rats (reproducing the same caloric restriction, as observed in hypoxic animals), in addition to the normoxic control fed ad libitum. The resting respiratory exchange ratio decreased after 21 days of exposure to hypobaric hypoxia (simulated elevation of 5,500 m). The respiration supported by pyruvate and octanoate were unaffected. In contrast, the maximal oxidative respiratory rate for PCoA, the transport of which depends on carnitine palmitoyltransferase 1 (CPT-1), decreased in the rapid-glycolytic EDL and increased in the slow-oxidative SOL, although hypoxia improved affinity for this substrate in both muscle types. PC and PCoA were oxidized similarly in normoxic EDL, whereas chronic hypoxia limited transport at the CPT-1 step in this muscle. The effects of hypoxia were mediated by caloric restriction in the SOL and by hypoxia itself in the EDL. We conclude that improvements in mitochondrial affinity for PCoA, a physiological long-chain fatty acid, would facilitate fatty-acid use at rest after chronic hypoxia independently of quantitative alterations of mitochondria. Conversely, decreasing the maximal oxidation of PCoA in fast-glycolytic muscles would limit fatty-acid use during exercise. NEW & NOTEWORTHY Affinity for low concentrations of long-chain fatty acids (LCFA) in mitochondria skeletal muscles increases after chronic hypoxia. Combined with a lower respiratory exchange ratio, this suggests facility for fatty acid utilization at rest. This fuel preference is related to caloric

A mitochondrial-targeted ubiquinone modulates muscle lipid profile and improves mitochondrial respiration in obesogenic diet-fed rats.

PubMed

Coudray, Charles; Fouret, Gilles; Lambert, Karen; Ferreri, Carla; Rieusset, Jennifer; Blachnio-Zabielska, Agnieszka; Lecomte, Jérôme; Ebabe Elle, Raymond; Badia, Eric; Murphy, Michael P; Feillet-Coudray, Christine

2016-04-14

The prevalence of the metabolic syndrome components including abdominal obesity, dyslipidaemia and insulin resistance is increasing in both developed and developing countries. It is generally accepted that the development of these features is preceded by, or accompanied with, impaired mitochondrial function. The present study was designed to analyse the effects of a mitochondrial-targeted lipophilic ubiquinone (MitoQ) on muscle lipid profile modulation and mitochondrial function in obesogenic diet-fed rats. For this purpose, twenty-four young male Sprague-Dawley rats were divided into three groups and fed one of the following diets: (1) control, (2) high fat (HF) and (3) HF+MitoQ. After 8 weeks, mitochondrial function markers and lipid metabolism/profile modifications in skeletal muscle were measured. The HF diet was effective at inducing the major features of the metabolic syndrome--namely, obesity, hepatic enlargement and glucose intolerance. MitoQ intake prevented the increase in rat body weight, attenuated the increase in adipose tissue and liver weights and partially reversed glucose intolerance. At the muscle level, the HF diet induced moderate TAG accumulation associated with important modifications in the muscle phospholipid classes and in the fatty acid composition of total muscle lipid. These lipid modifications were accompanied with decrease in mitochondrial respiration. MitoQ intake corrected the lipid alterations and restored mitochondrial respiration. These results indicate that MitoQ protected obesogenic diet-fed rats from some features of the metabolic syndrome through its effects on muscle lipid metabolism and mitochondrial activity. These findings suggest that MitoQ is a promising candidate for future human trials in the metabolic syndrome prevention.

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 function as a therapeutic target in heart failure

PubMed Central

Brown, David A.; Perry, Justin B.; Allen, Mitchell E.; Sabbah, Hani N.; Stauffer, Brian L.; Shaikh, Saame Raza; Cleland, John G. F.; Colucci, Wilson S.; Butler, Javed; Voors, Adriaan A.; Anker, Stefan D.; Pitt, Bertram; Pieske, Burkert; Filippatos, Gerasimos; Greene, Stephen J.; Gheorghiade, Mihai

2017-01-01

Heart failure is a pressing worldwide public-health problem with millions of patients having worsening heart failure. Despite all the available therapies, the condition carries a very poor prognosis. Existing therapies provide symptomatic and clinical benefit, but do not fully address molecular abnormalities that occur in cardiomyocytes. This shortcoming is particularly important given that most patients with heart failure have viable dysfunctional myocardium, in which an improvement or normalization of function might be possible. Although the pathophysiology of heart failure is complex, mitochondrial dysfunction seems to be an important target for therapy to improve cardiac function directly. Mitochondrial abnormalities include impaired mitochondrial electron transport chain activity, increased formation of reactive oxygen species, shifted metabolic substrate utilization, aberrant mitochondrial dynamics, and altered ion homeostasis. In this Consensus Statement, insights into the mechanisms of mitochondrial dysfunction in heart failure are presented, along with an overview of emerging treatments with the potential to improve the function of the failing heart by targeting mitochondria. PMID:28004807

Enhanced Neuroplasticity by the Metabolic Enhancer Piracetam Associated with Improved Mitochondrial Dynamics and Altered Permeability Transition Pore Function.

PubMed

Stockburger, Carola; Miano, Davide; Pallas, Thea; Friedland, Kristina; Müller, Walter E

2016-01-01

The mitochondrial cascade hypothesis of dementia assumes mitochondrial dysfunction leading to reduced energy supply, impaired neuroplasticity, and finally cell death as one major pathomechanism underlying the continuum from brain aging over mild cognitive impairment to initial and advanced late onset Alzheimer's disease. Accordingly, improving mitochondrial function has become an important strategy to treat the early stages of this continuum. The metabolic enhancer piracetam has been proposed as possible prototype for those compounds by increasing impaired mitochondrial function and related aspects like mechanisms of neuroplasticity. We here report that piracetam at therapeutically relevant concentrations improves neuritogenesis in the human cell line SH-SY5Y over conditions mirroring the whole spectrum of age-associated cognitive decline. These effects go parallel with improvement of impaired mitochondrial dynamics shifting back fission and fusion balance to the energetically more favorable fusion site. Impaired fission and fusion balance can also be induced by a reduction of the mitochondrial permeability transition pore (mPTP) function as atractyloside which indicates the mPTP has similar effects on mitochondrial dynamics. These changes are also reduced by piracetam. These findings suggest the mPTP as an important target for the beneficial effects of piracetam on mitochondrial function.

Mitochondrial biogenesis: pharmacological approaches.

PubMed

Valero, Teresa

2014-01-01

of human diseases arising from defects in mitochondrial ion and ROS homeostasis, energy production and morphology [1]. Parkinson´s Disease (PD) is a very good example of this important mitochondrial component on neurodegenerative diseases. Anuradha Yadav, Swati Agrawal, Shashi Kant Tiwari, and Rajnish K. Chaturvedi (CSIR-Indian Institute of Toxicology Research / Academy of Scientific and Innovative Research, India) [6] remark in their review the role of mitochondrial dysfunction in PD with special focus on the role of oxidative stress and bioenergetic deficits. These alterations may have their origin on pathogenic gene mutations in important genes such as DJ-1, -syn, parkin, PINK1 or LRRK2. These mutations, in turn, may cause defects in mitochondrial dynamics (key events like fission/fusion, biogenesis, trafficking in retrograde and anterograde directions, and mitophagy). This work reviews different strategies to enhance mitochondrial bioenergetics in order to ameliorate the neurodegenerative process, with an emphasis on clinical trials reports that indicate their potential. Among them creatine, Coenzyme Q10 and mitochondrial targeted antioxidants/peptides are reported to have the most remarkable effects in clinical trials. They highlight a dual effect of PGC-1α expression on PD prognosis. Whereas a modest expression of this transcriptional co-activator results in positive effects, a moderate to substantial overexpession may have deleterious consequences. As strategies to induce PGC-1α activation, these authors remark the possibility to activate Sirt1 with resveratrol, to use PPAR agonists such as pioglitazone, rosiglitazone, fenofibrate and bezafibrate. Other strategies include the triggering of Nrf2/antioxidant response element (ARE) pathway by triterpenoids (derivatives of oleanolic acid) or by Bacopa monniera, the enhancement of ATP production by carnitine and -lipoic acid. Mitochondrial dysfunctions are the prime source of neurodegenerative diseases and

Caenorhabditis elegans neuron degeneration and mitochondrial suppression caused by selected environmental chemicals

PubMed Central

Zhou, Shaoyu; Wang, Zemin; Klaunig, James E

2013-01-01

Mitochondrial alterations have been documented for many years in the brains of Parkinson’s disease (PD), a disorder that is characterized by the selective loss of dopamine neurons. Recent studies have demonstrated that Parkinson’s disease-associated proteins are either present in mitochondria or translocated into mitochondria in response to stress, further reinforcing the importance of the mitochondrial function in the pathogenesis of Parkinson’s disease. Exposure to environmental chemicals such as pesticides and heavy metals has been suggested as risk factors in the development of Parkinson’s disease. It has been reported that a number of environmental agents including tobacco smoke and perfluorinated compounds, pesticides, as well as metals (Mn2+ and Pb2+) modulate mitochondrial function. However the exact mechanism of mitochondrial alteration has not been defined in the context of the development and progression of Parkinson’s disease. The complexity of the mammalian system has made it difficult to dissect the molecular components involved in the pathogenesis of Parkinson’s disease. In the present study we used the nematode Caenorhabditis elegans (C. elegans) model of neuron degeneration and investigated the effect of environmental chemicals on mitochondrial biogenesis and mitochondrial gene regulation. Chronic exposure to low concentration (2 or 4 μM) of pesticide rotenone, resulted in significant loss of dopamine neuron in C. elegans, a classic feature of Parkinson’s disease. We then determined if the rotenone-induced neuron degeneration is accompanied by a change in mitochondria biogenesis. Analysis of mitochondrial genomic replication by quantitative PCR showed a dramatic decrease in mitochondrial DNA (mtDNA) copies of rotenone-treated C. elegans compared to control. This decreased mitochondrial biogenesis occurred prior to the development of loss of dopamine neurons, and was persistent. The inhibition of mtDNA replication was also found in C

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

AZT-induced mitochondrial toxicity: an epigenetic paradigm for dysregulation of gene expression through mitochondrial oxidative stress.

PubMed

Koczor, Christopher A; Jiao, Zhe; Fields, Earl; Russ, Rodney; Ludaway, Tomika; Lewis, William

2015-10-01

Mitochondrial dysfunction causes oxidative stress and cardiomyopathy. Oxidative stress also is a side effect of dideoxynucleoside antiretrovirals (NRTI) and is observed in NRTI-induced cardiomyopathy. We show here that treatment with the NRTI AZT {1-[(2R,4S,5S)-4-azido-5-(hydroxymethyl)oxolan-2-yl]-5-methylpyrimidine-2,4-dione} modulates cardiac gene expression epigenetically through production of mitochondrially derived reactive oxygen species. Transgenic mice with ubiquitous expression of mitochondrially targeted catalase (MCAT) and C57Bl/6 wild-type mice littermates (WT) were administered AZT (0.22 mg/day po, 35 days), and cardiac DNA and mRNA were isolated. In AZT-treated WT, 95 cardiac genes were differentially expressed compared with vehicle-treated WTs. When MCAT mice were treated with AZT, each of those 95 genes reverted toward the expression of vehicle-treated WTs. In AZT-treated WT hearts, Mthfr [5,10-methylenetetrahydrofolate reductase; a critical enzyme in synthesis of methionine cycle intermediates including S-adenosylmethionine (SAM)], was overexpressed. Steady-state abundance of SAM in cardiac extracts from AZT-treated MCAT mice increased 60% above that of vehicle-treated MCAT. No such change occurred in WT. AZT caused hypermethylation (47%) and hypomethylation (53%) of differentially methylated DNA regions in WT cardiac DNA. AZT-treated MCAT heart DNA exhibited greater hypermethylation (91%) and less hypomethylation (9%) compared with vehicle-treated MCAT controls. The gene encoding protein kinase C-α displayed multifocal epigenetic regulation caused by oxidative stress. Results show that mitochondrially derived oxidative stress in the heart hinders cardiac DNA methylation, alters steady-state abundance of SAM, alters cardiac gene expression, and promotes characteristic pathophysiological changes of cardiomyopathy. This mechanism for NRTI toxicity offers insight into long-term side effects from these commonly used antiviral agents. Copyright �

Manganese inhibits mitochondrial aconitase: a mechanism of manganese neurotoxicity1

PubMed Central

Zheng, Wei; Ren, Sean; Graziano, Joseph H.

2014-01-01

The symptoms of Mn-induced neurotoxicity resemble those of Parkinson’s diseases. Since iron (Fe) appears to play a pivotal role in pathophysiology of Parkinson’s disease, we set out to test the hypothesis that alterations in Fe-requiring enzymes such as aconitase contribute to Mn-induced neurotoxicity. Mitochondrial fractions prepared from rat brain were preincubated with MnCl2 in vitro, followed by the enzyme assay. Mn treatment significantly inhibited mitochondrial aconitase activity (24% inhibition at 625 μM to 81% at 2.5 mM, p < 0.05). The inhibitory effect was reversible and Mn-concentration dependent, and was reversed by the addition of Fe (0.05–1 mM) to the reaction mixture. In an in vivo chronic Mn exposure model, rats received intraperitoneal injection of 6 mg/kg Mn as MnCl2 once daily for 30 consecutive days. Mn exposure led to a region-specific alteration in total aconitase (i.e., mitochondrial + cytoplasmic): 48.5% reduction of the enzyme activity in frontal cortex (p < 0.01), 33.7% in striatum (p < 0.0963), and 20.6% in substantia nigra (p < 0.139). Chronic Mn exposure increased Mn concentrations in serum, CSF, and brain tissues. The elevation of Mn in all selected brain regions (range between 3.1 and 3.9 fold) was similar in magnitude to that in CSF (3.1 fold) rather than serum (6.1 fold). The present results suggest that Mn alters brain aconitase activity, which may lead to the disruption of mitochondrial energy production and cellular Fe metabolism in the brain. PMID:9675333

Mitochondrial Dysfunction, Disruption of F-Actin Polymerization, and Transcriptomic Alterations in Zebrafish Larvae Exposed to Trichloroethylene.

PubMed

Wirbisky, Sara E; Damayanti, Nur P; Mahapatra, Cecon T; Sepúlveda, Maria S; Irudayaraj, Joseph; Freeman, Jennifer L

2016-02-15

Trichloroethylene (TCE) is primarily used as an industrial degreasing agent and has been in use since the 1940s. TCE is released into the soil, surface, and groundwater. From an environmental and regulatory standpoint, more than half of Superfund hazardous waste sites on the National Priority List are contaminated with TCE. Occupational exposure to TCE occurs primarily via inhalation, while environmental TCE exposure also occurs through ingestion of contaminated drinking water. Current literature links TCE exposure to various adverse health effects including cardiovascular toxicity. Current studies aiming to address developmental cardiovascular toxicity utilized rodent and avian models, with the majority of studies using relatively higher parts per million (mg/L) doses. In this study, to further investigate developmental cardiotoxicity of TCE, zebrafish embryos were treated with 0, 10, 100, or 500 parts per billion (ppb; μg/L) TCE during embryogenesis and/or through early larval stages. After the appropriate exposure period, angiogenesis, F-actin, and mitochondrial function were assessed. A significant dose-response decrease in angiogenesis, F-actin, and mitochondrial function was observed. To further complement this data, a transcriptomic profile of zebrafish larvae was completed to identify gene alterations associated with the 10 ppb TCE exposure. Results from the transcriptomic data revealed that embryonic TCE exposure caused significant changes in genes associated with cardiovascular disease, cancer, and organismal injury and abnormalities with a number of targets in the FAK signaling pathway. Overall, results from our study support TCE as a developmental cardiovascular toxicant, provide molecular targets and pathways for investigation in future studies, and indicate a need for continued priority for environmental regulation.

Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons

PubMed Central

Magrané, Jordi; Sahawneh, Mary Anne; Przedborski, Serge; Estévez, Álvaro G.; Manfredi, Giovanni

2012-01-01

Mutations in Cu,Zn superoxide dismutase (SOD1) cause familial amyotrophic lateral sclerosis (FALS), a rapidly fatal motor neuron disease. Mutant SOD1 has pleiotropic toxic effects on motor neurons, among which mitochondrial dysfunction has been proposed as one of the contributing factors in motor neuron demise. Mitochondria are highly dynamic in neurons; they are constantly reshaped by fusion and move along neurites to localize at sites of high-energy utilization, such as synapses. The finding of abnormal mitochondria accumulation in neuromuscular junctions, where the SOD1-FALS degenerative process is though to initiate, suggests that impaired mitochondrial dynamics in motor neurons may be involved in pathogenesis. We addressed this hypothesis by live imaging microscopy of photo-switchable fluorescent mitoDendra in transgenic rat motor neurons expressing mutant or wild type human SOD1. We demonstrate that mutant SOD1 motor neurons have impaired mitochondrial fusion in axons and cell bodies. Mitochondria also display selective impairment of retrograde axonal transport, with reduced frequency and velocity of movements. Fusion and transport defects are associated with smaller mitochondrial size, decreased mitochondrial density, and defective mitochondrial membrane potential. Furthermore, mislocalization of mitochondria at synapses among motor neurons, in vitro, correlates with abnormal synaptic number, structure, and function. Dynamics abnormalities are specific to mutant SOD1 motor neuron mitochondria, since they are absent in wild type SOD1 motor neurons, they do not involve other organelles, and they are not found in cortical neurons. Taken together, these results suggest that impaired mitochondrial dynamics may contribute to the selective degeneration of motor neurons in SOD1-FALS. PMID:22219285

Developmental exposure to second-hand smoke increases adult atherogenesis and alters mitochondrial DNA copy number and deletions in apoE(-/-) mice.

PubMed

Fetterman, Jessica L; Pompilius, Melissa; Westbrook, David G; Uyeminami, Dale; Brown, Jamelle; Pinkerton, Kent E; Ballinger, Scott W

2013-01-01

Cardiovascular disease is a major cause of morbidity and mortality in the United States. While many studies have focused upon the effects of adult second-hand smoke exposure on cardiovascular disease development, disease development occurs over decades and is likely influenced by childhood exposure. The impacts of in utero versus neonatal second-hand smoke exposure on adult atherosclerotic disease development are not known. The objective of the current study was to determine the effects of in utero versus neonatal exposure to a low dose (1 mg/m(3) total suspended particulate) of second-hand smoke on adult atherosclerotic lesion development using the apolipoprotein E null mouse model. Consequently, apolipoprotein E null mice were exposed to either filtered air or second-hand smoke: (i) in utero from gestation days 1-19, or (ii) from birth until 3 weeks of age (neonatal). Subsequently, all animals were exposed to filtered air and sacrificed at 12-14 weeks of age. Oil red-O staining of whole aortas, measures of mitochondrial damage, and oxidative stress were performed. Results show that both in utero and neonatal second-hand smoke exposure significantly increased adult atherogenesis in mice compared to filtered air controls. These changes were associated with changes in aconitase and mitochondrial superoxide dismutase activities consistent with increased oxidative stress in the aorta, changes in mitochondrial DNA copy number and deletion levels. These studies show that in utero or neonatal exposure to second-hand smoke significantly influences adult atherosclerotic lesion development and results in significant alterations to the mitochondrion and its genome that may contribute to atherogenesis.

Murine Mesenchymal Stem Cell Commitment to Differentiation is Regulated by Mitochondrial Dynamics

PubMed Central

Forni, Maria Fernanda; Peloggia, Julia; Trudeau, Kyle; Shirihai, Orian; Kowaltowski, Alicia J.

2015-01-01

Mouse skin mesenchymal stem cells (msMSCs) are dermis CD105+CD90+CD73+CD29+CD34− mesodermal precursors which, after in vitro induction, undergo chondro, adipo and osteogenesis. Extensive metabolic reconfiguration has been found to occur during differentiation, and the bioenergetic status of a cell is known to be dependent on the quality and abundance of the mitochondrial population, which may be regulated by fusion and fission. However, little is known regarding the impact of mitochondrial dynamics on the differentiation process. We addressed this knowledge gap by isolating MSCs from Swiss female mice, inducing these cells to differentiate into osteo, chondro and adipocytes and measuring changes in mass, morphology, dynamics and bioenergetics. Mitochondrial biogenesis was increased in adipogenesis, as evaluated through confocal microscopy, citrate synthase activity and mtDNA content. The early steps of adipo and osteogenesis involved mitochondrial elongation, as well as increased expression of mitochondrial fusion proteins Mfn1 and 2. Chondrogenesis involved a fragmented mitochondrial phenotype, increased expression of fission proteins Drp1, Fis1 and 2 and enhanced mitophagy. These events were accompanied by profound bioenergetic alterations during the commitment period. Moreover, knockdown of Mfn2 in adipo and osteogenesis and the overexpression of a dominant negative form of Drp1 during chondrogenesis resulted in a loss of differentiation ability. Overall, we find that mitochondrial morphology and its regulating processes of fission/fusion are modulated early on during commitment, leading to alterations in the bioenergetic profile that are important for differentiation. We thus propose a central role for mitochondrial dynamics in the maintenance/commitment of mesenchymal stem cells. PMID:26638184

Enhanced Neuroplasticity by the Metabolic Enhancer Piracetam Associated with Improved Mitochondrial Dynamics and Altered Permeability Transition Pore Function

PubMed Central

Stockburger, Carola; Miano, Davide; Pallas, Thea; Müller, Walter E.

2016-01-01

The mitochondrial cascade hypothesis of dementia assumes mitochondrial dysfunction leading to reduced energy supply, impaired neuroplasticity, and finally cell death as one major pathomechanism underlying the continuum from brain aging over mild cognitive impairment to initial and advanced late onset Alzheimer's disease. Accordingly, improving mitochondrial function has become an important strategy to treat the early stages of this continuum. The metabolic enhancer piracetam has been proposed as possible prototype for those compounds by increasing impaired mitochondrial function and related aspects like mechanisms of neuroplasticity. We here report that piracetam at therapeutically relevant concentrations improves neuritogenesis in the human cell line SH-SY5Y over conditions mirroring the whole spectrum of age-associated cognitive decline. These effects go parallel with improvement of impaired mitochondrial dynamics shifting back fission and fusion balance to the energetically more favorable fusion site. Impaired fission and fusion balance can also be induced by a reduction of the mitochondrial permeability transition pore (mPTP) function as atractyloside which indicates the mPTP has similar effects on mitochondrial dynamics. These changes are also reduced by piracetam. These findings suggest the mPTP as an important target for the beneficial effects of piracetam on mitochondrial function. PMID:27747106

Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans

PubMed Central

MJ, Falk; Z, Zhang; Rosenjack; Nissim; E, Daikhin; Nissim; MM, Sedensky; M, Yudkoff; PG, Morgan

2008-01-01

C. elegans affords a model of primary mitochondrial dysfunction that provides insight into cellular adaptations which accompany mutations in nuclear gene that encode mitochondrial proteins. To this end, we characterized genome-wide expression profiles of C. elegans strains with mutations in nuclear-encoded subunits of respiratory chain complexes. Our goal was to detect concordant changes among clusters of genes that comprise defined metabolic pathways. Results indicate that respiratory chain mutants significantly upregulate a variety of basic cellular metabolic pathways involved in carbohydrate, amino acid, and fatty acid metabolism, as well as cellular defense pathways such as the metabolism of P450 and glutathione. To further confirm and extend expression analysis findings, quantitation of whole worm free amino acid levels was performed in C. elegans mitochondrial mutants for subunits of complexes I, II, and III. Significant differences were seen for 13 of 16 amino acid levels in complex I mutants compared with controls, as well as overarching similarities among profiles of complex I, II, and III mutants compared with controls. The specific pattern of amino acid alterations observed provides novel evidence to suggest that an increase in glutamate-linked transamination reactions caused by the failure of NAD+ dependent oxidation of ketoacids occurs in primary mitochondrial respiratory chain mutants. Recognition of consistent alterations among patterns of nuclear gene expression for multiple biochemical pathways and in quantitative amino acid profiles in a translational genetic model of mitochondrial dysfunction allows insight into the complex pathogenesis underlying primary mitochondrial disease. Such knowledge may enable the development of a metabolomic profiling diagnostic tool applicable to human mitochondrial disease. PMID:18178500

Adolescent Binge Alcohol Exposure Affects the Brain Function Through Mitochondrial Impairment.

PubMed

Tapia-Rojas, Cheril; Carvajal, Francisco J; Mira, Rodrigo G; Arce, Camila; Lerma-Cabrera, José Manuel; Orellana, Juan A; Cerpa, Waldo; Quintanilla, Rodrigo A

2018-05-01

In the young population, binge drinking is a pattern of problematic alcohol consumption, characterized by a short period of heavy drinking followed by abstinence which is frequently repeated over time. This drinking pattern is associated with mental problems, use of other drugs, and an increased risk of excessive alcohol intake during adulthood. However, little is known about the effects of binge drinking on brain function in adolescents and its neurobiological impact during the adulthood. In the present study, we evaluated the effects of alcohol on hippocampal memory, synaptic plasticity, and mitochondrial function in adolescent rats after a binge drinking episode in vivo. These effects were analyzed at 1, 3, or 7 weeks post alcohol exposure. Our results showed that binge-like ethanol pre-treated (BEP) rats exhibited early alterations in learning and memory tests accompanied by an impairment of synaptic plasticity that was total and partially compensated, respectively. These changes could be attributed to a rapid increase in oxidative damage and a late inflammatory response induced by post ethanol exposure. Additionally, BEP alters the regulation of mitochondrial dynamics and modifies the expression of mitochondrial permeability transition pore (mPTP) components, such as cyclophilin D (Cyp-D) and the voltage-dependent anion channel (VDAC). These mitochondrial structural changes result in the impairment of mitochondrial bioenergetics, decreasing ATP production progressively until adulthood. These results strongly suggest that teenage alcohol binge drinking impairs the function of the adult hippocampus including memory and synaptic plasticity as a consequence of the mitochondrial damage induced by alcohol and that the recovery of hippocampal function could implicate the activation of alternative pathways that fail to reestablish mitochondrial function.

Response of mitochondrial function to hypothyroidism in normal and regenerated rat skeletal muscle.

PubMed

Zoll, J; Ventura-Clapier, R; Serrurier, B; Bigard, A X

2001-01-01

Although thyroid hormones induce a well known decrease in muscle oxidative capacity, nothing is known concerning their effects on mitochondrial function and regulation in situ. Similarly, the influence of regeneration process is not completely understood. We investigated the effects of hypothyroidism on mitochondrial function in fast gastrocnemius (GS) and slow soleus (SOL) muscles either intact or having undergone a cycle of degeneration/regeneration (Rg SOL) following a local injection of myotoxin. Thyroid hormone deficiency was induced by thyroidectomy and propylthiouracyl via drinking water. Respiration was measured in muscle fibres permeabilised by saponin in order to assess the oxidative capacity of the muscles and the regulation of mitochondria in situ. Oxidative capacities were 8.9 in SOL, 8.5 in Rg SOL and 5.9 micromol O2/min/g dry weight in GS and decreased by 52, 42 and 39% respectively (P < 0.001) in hypothyroid rats. Moreover, the Km of mitochondrial respiration for the phosphate acceptor ADP exhibited a two-fold decrease in Rg SOL and intact SOL by hypothyroidism (P < 0.01), while mitochondrial creatine kinase activity and sensitivity of mitochondrial respiration to creatine were not altered. The results of this study demonstrate that hypothyroidism markedly altered the sensitivity of mitochondrial respiration to ADP but not to creatine in SOL muscles, suggesting that mitochondrial regulation could be partially controlled by thyroid hormones. On the other hand, mitochondrial function completely recovered following regeneration/degeneration, suggesting that thyroid hormones are not involved in the regeneration process per se.

Valproic acid triggers increased mitochondrial biogenesis in POLG-deficient fibroblasts

PubMed Central

Sitarz, Kamil S.; Elliott, Hannah R.; Karaman, Betül S.; Relton, Caroline; Chinnery, Patrick F.; Horvath, Rita

2014-01-01

Valproic acid (VPA) is a widely used antiepileptic drug and also prescribed to treat migraine, chronic headache and bipolar disorder. Although it is usually well tolerated, a severe hepatotoxic reaction has been repeatedly reported after VPA administration. A profound toxic reaction on administration of VPA has been observed in several patients carrying POLG mutations, and heterozygous genetic variation in POLG has been strongly associated with VPA-induced liver toxicity. Here we studied the effect of VPA in fibroblasts of five patients carrying pathogenic mutations in the POLG gene. VPA administration caused a significant increase in the expression of POLG and several regulators of mitochondrial biogenesis. It was further supported by elevated mtDNA copy numbers. The effect of VPA on mitochondrial biogenesis was observed in both control and patient cell lines, but the capacity of mutant POLG to increase the expression of mitochondrial genes and to increase mtDNA copy numbers was less effective. No evidence of substantive differences in DNA methylation across the genome was observed between POLG mutated patients and controls. Given the marked perturbation of gene expression observed in the cell lines studied, we conclude that altered DNA methylation is unlikely to make a major contribution to POLG-mediated VPA toxicity. Our data provide experimental evidence that VPA triggers increased mitochondrial biogenesis by altering the expression of several mitochondrial genes; however, the capacity of POLG-deficient liver cells to address the increased metabolic rate caused by VPA administration is significantly impaired. PMID:24725338

Deoxynucleoside stress exacerbates the phenotype of a mouse model of mitochondrial neurogastrointestinal encephalopathy

PubMed Central

Garcia-Diaz, Beatriz; Garone, Caterina; Barca, Emanuele; Mojahed, Hamed; Gutierrez, Purification; Pizzorno, Giuseppe; Tanji, Kurenai; Arias-Mendoza, Fernando; Quinzii, Caterina M.

2014-01-01

Balanced pools of deoxyribonucleoside triphosphate precursors are required for DNA replication, and alterations of this balance are relevant to human mitochondrial diseases including mitochondrial neurogastrointestinal encephalopathy. In this disease, autosomal recessive TYMP mutations cause severe reductions of thymidine phosphorylase activity; marked elevations of the pyrimidine nucleosides thymidine and deoxyuridine in plasma and tissues, and somatic multiple deletions, depletion and site-specific point mutations of mitochondrial DNA. Thymidine phosphorylase and uridine phosphorylase double knockout mice recapitulated several features of these patients including thymidine phosphorylase activity deficiency, elevated thymidine and deoxyuridine in tissues, mitochondrial DNA depletion, respiratory chain defects and white matter changes. However, in contrast to patients with this disease, mutant mice showed mitochondrial alterations only in the brain. To test the hypothesis that elevated levels of nucleotides cause unbalanced deoxyribonucleoside triphosphate pools and, in turn, pathogenic mitochondrial DNA instability, we have stressed double knockout mice with exogenous thymidine and deoxyuridine, and assessed clinical, neuroradiological, histological, molecular, and biochemical consequences. Mutant mice treated with exogenous thymidine and deoxyuridine showed reduced survival, body weight, and muscle strength, relative to untreated animals. Moreover, in treated mutants, leukoencephalopathy, a hallmark of the disease, was enhanced and the small intestine showed a reduction of smooth muscle cells and increased fibrosis. Levels of mitochondrial DNA were depleted not only in the brain but also in the small intestine, and deoxyribonucleoside triphosphate imbalance was observed in the brain. The relative proportion, rather than the absolute amount of deoxyribonucleoside triphosphate, was critical for mitochondrial DNA maintenance. Thus, our results demonstrate that

Adaptations Required for Mitochondrial Import following Mitochondrial to Nucleus Gene Transfer of Ribosomal Protein S101[w

PubMed Central

Murcha, Monika W.; Rudhe, Charlotta; Elhafez, Dina; Adams, Keith L.; Daley, Daniel O.; Whelan, James

2005-01-01

The minimal requirements to support protein import into mitochondria were investigated in the context of the phenomenon of ongoing gene transfer from the mitochondrion to the nucleus in plants. Ribosomal protein 10 of the small subunit is encoded in the mitochondrion in soybean and many other angiosperms, whereas in several other species it is nuclear encoded and thus must be imported into the mitochondrial matrix to function. When encoded by the nuclear genome, it has adopted different strategies for mitochondrial targeting and import. In lettuce (Lactuca sativa) and carrot (Daucus carota), Rps10 independently gained different N-terminal extensions from other genes, following transfer to the nucleus. (The designation of Rps10 follows the following convention. The gene is indicated in italics. If encoded in the mitochondrion, it is rps10; if encoded in the nucleus, it is Rps10.) Here, we show that the N-terminal extensions of Rps10 in lettuce and carrot are both essential for mitochondrial import. In maize (Zea mays), Rps10 has not acquired an extension upon transfer but can be readily imported into mitochondria. Deletion analysis located the mitochondrial targeting region to the first 20 amino acids. Using site directed mutagenesis, we changed residues in the first 20 amino acids of the mitochondrial encoded soybean (Glycine max) rps10 to the corresponding amino acids in the nuclear encoded maize Rps10 until import was achieved. Changes were required that altered charge, hydrophobicity, predicted ability to form an amphiphatic α-helix, and generation of a binding motif for the outer mitochondrial membrane receptor, translocase of the outer membrane 20. In addition to defining the changes required to achieve mitochondrial localization, the results demonstrate that even proteins that do not present barriers to import can require substantial changes to acquire a mitochondrial targeting signal. PMID:16040655

Impact of Aging and Exercise on Mitochondrial Quality Control in Skeletal Muscle

PubMed Central

Kim, Yuho; Triolo, Matthew

2017-01-01

Mitochondria are characterized by its pivotal roles in managing energy production, reactive oxygen species, and calcium, whose aging-related structural and functional deteriorations are observed in aging muscle. Although it is still unclear how aging alters mitochondrial quality and quantity in skeletal muscle, dysregulation of mitochondrial biogenesis and dynamic controls has been suggested as key players for that. In this paper, we summarize current understandings on how aging regulates muscle mitochondrial biogenesis, while focusing on transcriptional regulations including PGC-1α, AMPK, p53, mtDNA, and Tfam. Further, we review current findings on the muscle mitochondrial dynamic systems in aging muscle: fusion/fission, autophagy/mitophagy, and protein import. Next, we also discuss how endurance and resistance exercises impact on the mitochondrial quality controls in aging muscle, suggesting possible effective exercise strategies to improve/maintain mitochondrial health. PMID:28656072

Changes in nuclear receptor corepressor RIP140 do not influence mitochondrial content in the cortex.

PubMed

Herbst, Eric A F; Bonen, Arend; Holloway, Graham P

2015-10-01

Changes in nuclear receptor interacting protein 140 (RIP140) influences mitochondrial content in skeletal muscle; however, the translation of these findings to the brain has not been investigated. The present study examined the impact of overexpressing and ablating RIP140 on mitochondrial content in muscle and the cortex through examining mRNA, mtDNA, and mitochondrial protein content. Our results show that changes in RIP140 expression significantly alters markers of mitochondrial content in skeletal muscle but not the brain.

Mitochondrial dynamics in mammalian health and disease.

PubMed

Liesa, Marc; Palacín, Manuel; Zorzano, Antonio

2009-07-01

The meaning of the word mitochondrion (from the Greek mitos, meaning thread, and chondros, grain) illustrates that the heterogeneity of mitochondrial morphology has been known since the first descriptions of this organelle. Such a heterogeneous morphology is explained by the dynamic nature of mitochondria. Mitochondrial dynamics is a concept that includes the movement of mitochondria along the cytoskeleton, the regulation of mitochondrial architecture (morphology and distribution), and connectivity mediated by tethering and fusion/fission events. The relevance of these events in mitochondrial and cell physiology has been partially unraveled after the identification of the genes responsible for mitochondrial fusion and fission. Furthermore, during the last decade, it has been identified that mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause prevalent neurodegenerative diseases (Charcot-Marie Tooth type 2A and Kjer disease/autosomal dominant optic atrophy). In addition, other diseases such as type 2 diabetes or vascular proliferative disorders show impaired MFN2 expression. Altogether, these findings have established mitochondrial dynamics as a consolidated area in cellular physiology. Here we review the most significant findings in the field of mitochondrial dynamics in mammalian cells and their implication in human pathologies.

Mitochondrial protein hyperacetylation in the failing heart

PubMed Central

Horton, Julie L.; Martin, Ola J.; Lai, Ling; Richards, Alicia L.; Vega, Rick B.; Leone, Teresa C.; Pagliarini, David J.; Muoio, Deborah M.; Bedi, Kenneth C.; Coon, Joshua J.

2016-01-01

Myocardial fuel and energy metabolic derangements contribute to the pathogenesis of heart failure. Recent evidence implicates posttranslational mechanisms in the energy metabolic disturbances that contribute to the pathogenesis of heart failure. We hypothesized that accumulation of metabolite intermediates of fuel oxidation pathways drives posttranslational modifications of mitochondrial proteins during the development of heart failure. Myocardial acetylproteomics demonstrated extensive mitochondrial protein lysine hyperacetylation in the early stages of heart failure in well-defined mouse models and the in end-stage failing human heart. To determine the functional impact of increased mitochondrial protein acetylation, we focused on succinate dehydrogenase A (SDHA), a critical component of both the tricarboxylic acid (TCA) cycle and respiratory complex II. An acetyl-mimetic mutation targeting an SDHA lysine residue shown to be hyperacetylated in the failing human heart reduced catalytic function and reduced complex II–driven respiration. These results identify alterations in mitochondrial acetyl-CoA homeostasis as a potential driver of the development of energy metabolic derangements that contribute to heart failure. PMID:26998524

Somatic mitochondrial mutation in gastric cancer.

PubMed Central

Burgart, L. J.; Zheng, J.; Shu, Q.; Strickler, J. G.; Shibata, D.

1995-01-01

Likely hot spots for mutations are mitochondrial sequences as there is less repair and more damage by carcinogens compared with nuclear sequences. A somatic 50-bp mitochondrial D-loop deletion was detected in four gastric adenocarcinomas. The deletion included the CSB2 region and was flanked by 9-bp direct repeats. The deletion was more frequent in adenocarcinomas arising from the gastroesophageal junction (4/32, 12.5%) compared with more distal tumors (0/45). Topographical analysis revealed the absence of the deletion from normal tissues except in focal portions of smooth muscle in one case. In two cases, apparent mutant homoplasmy was present throughout two tumors, including their metastases. In the two other cases, the mutation was present in only minor focal portions ( < 5%) of their primary tumors. These findings document the presence of somatic mitochondrial alterations in gastric cancer, which may reflect the environmental and genetic influences operative during tumor progression. Images Figure 3 Figure 4 Figure 5 PMID:7573355

Alterations in the characteristic size distributions of subcellular scatterers at the onset of apoptosis: effect of Bcl-xL and Bax/Bak

NASA Astrophysics Data System (ADS)

Zheng, Jing-Yi; Boustany, Nada N.

2010-07-01

Optical scatter imaging is used to estimate organelle size distributions in immortalized baby mouse kidney cells treated with 0.4 μM staurosporine to induce apoptosis. The study comprises apoptosis competent iBMK cells (W2) expressing the proapoptotic proteins Bax/Bak, apoptosis resistant Bax/Bak null cells (D3), and W2 and D3 cells expressing yellow fluorescent protein (YFP) or YFP fused to the antiapoptotic protein Bcl-xL (YFP-Bcl-xL). YFP expression is diffuse within the transfected cells, while YFP-Bcl-xL is localized to the mitochondria. Our results show a significant increase in the mean subcellular particle size from approximately 1.1 to 1.4 μm in both Bax/Bak expressing and Bax/Bak null cells after 60 min of STS treatment compared to DMSO-treated control cells. This dynamic is blocked by overexpression of YFP-Bcl-xL in Bax/Bak expressing cells, but is less significantly inhibited by YFP-Bcl-xL in Bax/Bak null cells. Our data suggest that the increase in subcellular particle size at the onset of apoptosis is modulated by Bcl-xL in the presence of Bax/Bak, but it occurs upstream of the final commitment to programmed cell death. Mitochondrial localization of YFP-Bcl-xL and the finding that micron-sized particles give rise to the scattering signal further suggest that alterations in mitochondrial morphology may underlie the observed changes in light scattering.

Loss of Miro1-directed mitochondrial movement results in a novel murine model for neuron disease

PubMed Central

Nguyen, Tammy T.; Oh, Sang S.; Weaver, David; Lewandowska, Agnieszka; Maxfield, Dane; Schuler, Max-Hinderk; Smith, Nathan K.; Macfarlane, Jane; Saunders, Gerald; Palmer, Cheryl A.; Debattisti, Valentina; Koshiba, Takumi; Pulst, Stefan; Feldman, Eva L.; Hajnóczky, György; Shaw, Janet M.

2014-01-01

Defective mitochondrial distribution in neurons is proposed to cause ATP depletion and calcium-buffering deficiencies that compromise cell function. However, it is unclear whether aberrant mitochondrial motility and distribution alone are sufficient to cause neurological disease. Calcium-binding mitochondrial Rho (Miro) GTPases attach mitochondria to motor proteins for anterograde and retrograde transport in neurons. Using two new KO mouse models, we demonstrate that Miro1 is essential for development of cranial motor nuclei required for respiratory control and maintenance of upper motor neurons required for ambulation. Neuron-specific loss of Miro1 causes depletion of mitochondria from corticospinal tract axons and progressive neurological deficits mirroring human upper motor neuron disease. Although Miro1-deficient neurons exhibit defects in retrograde axonal mitochondrial transport, mitochondrial respiratory function continues. Moreover, Miro1 is not essential for calcium-mediated inhibition of mitochondrial movement or mitochondrial calcium buffering. Our findings indicate that defects in mitochondrial motility and distribution are sufficient to cause neurological disease. PMID:25136135

ATPase-deficient mitochondrial inner membrane protein ATAD3A disturbs mitochondrial dynamics in dominant hereditary spastic paraplegia

PubMed Central

Cooper, Helen M.; Yang, Yang; Ylikallio, Emil; Khairullin, Rafil; Woldegebriel, Rosa; Lin, Kai-Lan; Euro, Liliya; Palin, Eino; Wolf, Alexander; Trokovic, Ras; Isohanni, Pirjo; Kaakkola, Seppo; Auranen, Mari; Lönnqvist, Tuula; Wanrooij, Sjoerd

2017-01-01

Abstract De novo mutations in ATAD3A (ATPase family AAA-domain containing protein 3A) were recently found to cause a neurological syndrome with developmental delay, hypotonia, spasticity, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. Using whole-exome sequencing, we identified a dominantly inherited heterozygous variant c.1064G > A (p.G355D) in ATAD3A in a mother presenting with hereditary spastic paraplegia (HSP) and axonal neuropathy and her son with dyskinetic cerebral palsy, both with disease onset in childhood. HSP is a clinically and genetically heterogeneous disorder of the upper motor neurons. Symptoms beginning in early childhood may resemble spastic cerebral palsy. The function of ATAD3A, a mitochondrial inner membrane AAA ATPase, is yet undefined. AAA ATPases form hexameric rings, which are catalytically dependent on the co-operation of the subunits. The dominant-negative patient mutation affects the Walker A motif, which is responsible for ATP binding in the AAA module of ATAD3A, and we show that the recombinant mutant ATAD3A protein has a markedly reduced ATPase activity. We further show that overexpression of the mutant ATAD3A fragments the mitochondrial network and induces lysosome mass. Similarly, we observed altered dynamics of the mitochondrial network and increased lysosomes in patient fibroblasts and neurons derived through differentiation of patient-specific induced pluripotent stem cells. These alterations were verified in patient fibroblasts to associate with upregulated basal autophagy through mTOR inactivation, resembling starvation. Mutations in ATAD3A can thus be dominantly inherited and underlie variable neurological phenotypes, including HSP, with intrafamiliar variability. This finding extends the group of mitochondrial inner membrane AAA proteins associated with spasticity. PMID:28158749

Chemoprevention of obesity by dietary natural compounds targeting mitochondrial regulation.

PubMed

Lai, Ching-Shu; Wu, Jia-Ching; Ho, Chi-Tang; Pan, Min-Hsiung

2017-06-01

Mitochondria are at the center stage in the control of energy homeostasis in many organs and tissues including adipose tissue. Recently, abundant evidence from experimental studies has clearly supported the strong correlation between mitochondrial dysfunction in adipocytes and obesity. Various physiological conditions such as excessive nutrition, genetic factors, hypoxia, and toxins disrupt mitochondrial function by impairing mitochondrial biogenesis, dynamics, and oxidative capacity. Mitochondrial dysfunction in adipocytes could have an impact on differentiation, adipogenesis, insulin sensitivity, and the significant alteration in their metabolic function, which ultimately results in obesity and type 2 diabetes. Numerous dietary natural compounds are the subject of research for the prevention and treatment of obesity through reprogramming multiple metabolic pathways. Some of them have the potential against obesity by modulating insulin signaling, decreasing oxidative damage, downregulating adipokines secretion, and increasing mitochondrial DNA that improves mitochondrial function and thus maintain metabolic homeostasis. Here, we focus on and summarize and briefly discuss the currently known targets and the mitochondria-targeting effects of dietary natural compounds in the intervention of obesity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Absence of detectable mitochondrial recombination in Paramecium.

PubMed

Adoutte, A; Knowles, J K; Sainsard-Chanet, A

1979-12-01

An extensive search for recombination between mitochondrial markers was carried out in Paramecium tetraurelia. Thirty-two combinations, altogether involving 24 different markers, were studied. The markers belonged to the three main categories of mitochondrial mutations presently available in this organism, (a) Spontaneous or UV-induced antibiotic resistance mutations, most probably affecting mitochondrial ribosomes, (b) nitrosoguanidine-induced antibiotic resistance markers displaying thermosensitivity or slow growth, enabling easy selection of possible wild-type recombinants, and (c) mitochondrial partial suppressors of a nuclear gene, probably corresponding to molecular alterations distinct from the preceding two categories. In addition, different genetic configurations were analyzed (i.e., mutant X mutant, double-mutant X wild-type, etc.).--None of the combinations yielded any evidence for the occurrence of recombined genomes despite the fact that: (1) all of them were studied on a large scale involving the screening of at least several thousand mitochondrial genomes (often several millions), (2) in many of them the detection level was sufficiently high to enable the isolation of spontaneous mutants in control cells, and (3) in several of them, reconstitution experiments carried out in parallel show that the conditions were fully adequate to detect recombinant genotypes. The results are in marked contrast with those obtained on the few other organisms in which mitochondrial recombination has been studied, particularly Saccharomyces cerevisiae, in which mitochondrial recombination is intense.--The most likely basis for the various manifestations of mitochondrial genetic autonomy in Paramecium, described in this as well as in previous publications, is that the chondriome of this organism is made up of thousands of structurally discrete, noninteracting units.

Normalization of High Dimensional Genomics Data Where the Distribution of the Altered Variables Is Skewed

PubMed Central

Landfors, Mattias; Philip, Philge; Rydén, Patrik; Stenberg, Per

2011-01-01

Genome-wide analysis of gene expression or protein binding patterns using different array or sequencing based technologies is now routinely performed to compare different populations, such as treatment and reference groups. It is often necessary to normalize the data obtained to remove technical variation introduced in the course of conducting experimental work, but standard normalization techniques are not capable of eliminating technical bias in cases where the distribution of the truly altered variables is skewed, i.e. when a large fraction of the variables are either positively or negatively affected by the treatment. However, several experiments are likely to generate such skewed distributions, including ChIP-chip experiments for the study of chromatin, gene expression experiments for the study of apoptosis, and SNP-studies of copy number variation in normal and tumour tissues. A preliminary study using spike-in array data established that the capacity of an experiment to identify altered variables and generate unbiased estimates of the fold change decreases as the fraction of altered variables and the skewness increases. We propose the following work-flow for analyzing high-dimensional experiments with regions of altered variables: (1) Pre-process raw data using one of the standard normalization techniques. (2) Investigate if the distribution of the altered variables is skewed. (3) If the distribution is not believed to be skewed, no additional normalization is needed. Otherwise, re-normalize the data using a novel HMM-assisted normalization procedure. (4) Perform downstream analysis. Here, ChIP-chip data and simulated data were used to evaluate the performance of the work-flow. It was found that skewed distributions can be detected by using the novel DSE-test (Detection of Skewed Experiments). Furthermore, applying the HMM-assisted normalization to experiments where the distribution of the truly altered variables is skewed results in considerably higher

Mitochondrial transcription factor A (Tfam) gene sequencing and mitochondrial evaluation in inherited retinal dysplasia in miniature schnauzer dogs.

PubMed

Bauer, Bianca S; Forsyth, George W; Sandmeyer, Lynne S; Grahn, Bruce H

2011-04-01

Mitochondrial transcription factor A (Tfam) has been implicated in the pathogenesis of retinal dysplasia in miniature schnauzer dogs and it has been proposed that affected dogs have altered mitochondrial numbers, size, and morphology. To test these hypotheses the Tfam gene of affected and normal miniature schnauzer dogs with retinal dysplasia was sequenced and lymphocyte mitochondria were quantified, measured, and the morphology was compared in normal and affected dogs using transmission electron microscopy. For Tfam sequencing, retina, retinal pigment epithelium (RPE), and whole blood samples were collected. Total RNA was isolated from the retina and RPE and reverse transcribed to make cDNA. Genomic DNA was extracted from white blood cell pellets obtained from the whole blood samples. The Tfam coding sequence, 5' promoter region, intron1 and the 3' non-coding sequence of normal and affected dogs were amplified using polymerase chain reaction (PCR), cloned and sequenced. For electron microscopy, lymphocytes from affected and normal dogs were photographed and the mitochondria within each cross-section were identified, quantified, and the mitochondrial area (μm²) per lymphocyte cross-section was calculated. Lastly, using a masked technique, mitochondrial morphology was compared between the 2 groups. Sequencing of the miniature schnauzer Tfam gene revealed no functional sequence variation between affected and normal dogs. Lymphocyte and mitochondrial area, mitochondrial quantification, and morphology assessment also revealed no significant difference between the 2 groups. Further investigation into other candidate genes or factors causing retinal dysplasia in the miniature schnauzer is warranted.

Changes in mitochondrial dynamics during ceramide-induced cardiomyocyte early apoptosis.

PubMed

Parra, Valentina; Eisner, Veronica; Chiong, Mario; Criollo, Alfredo; Moraga, Francisco; Garcia, Alejandra; Härtel, Steffen; Jaimovich, Enrique; Zorzano, Antonio; Hidalgo, Cecilia; Lavandero, Sergio

2008-01-15

In cells, mitochondria are organized as a network of interconnected organelles that fluctuate between fission and fusion events (mitochondrial dynamics). This process is associated with cell death. We investigated whether activation of apoptosis with ceramides affects mitochondrial dynamics and promotes mitochondrial fission in cardiomyocytes. Neonatal rat cardiomyocytes were incubated with C(2)-ceramide or the inactive analog dihydro-C(2)-ceramide for up to 6 h. Three-dimensional images of cells loaded with mitotracker green were obtained by confocal microscopy. Dynamin-related protein-1 (Drp-1) and mitochondrial fission protein 1 (Fis1) distribution and levels were studied by immunofluorescence and western blot. Mitochondrial membrane potential (DeltaPsi(m)) and cytochrome c (cyt c) distribution were used as indexes of early activation of apoptosis. Cell viability and DNA fragmentation were determined by propidium iodide staining/flow cytometry, whereas cytotoxicity was evaluated by lactic dehydrogenase activity. To decrease the levels of the mitochondrial fusion protein mitofusin 2, we used an antisense adenovirus (AsMfn2). C(2)-ceramide, but not dihydro-C(2)-ceramide, promoted rapid fragmentation of the mitochondrial network in a concentration- and time-dependent manner. C(2)-ceramide also increased mitochondrial Drp-1 and Fis1 content, Drp-1 colocalization with Fis1, and caused early activation of apoptosis. AsMfn2 accentuated the decrease in DeltaPsi(m) and cyt c redistribution induced by C(2)-ceramide. Doxorubicin, which induces cardiomyopathy and apoptosis through ceramide generation, also stimulated mitochondrial fragmentation. Ceramides stimulate mitochondrial fission and this event is associated with early activation of cardiomyocyte apoptosis.

Mitochondrial dysfunction and insulin resistance from the outside in: extracellular matrix, the cytoskeleton, and mitochondria

PubMed Central

Coletta, Dawn K.

2011-01-01

Insulin resistance in skeletal muscle is a prominent feature of obesity and type 2 diabetes. The association between mitochondrial changes and insulin resistance is well known. More recently, there is growing evidence of a relationship between inflammation, extracellular remodeling, and insulin resistance. The intent of this review is to propose a potentially novel mechanism for the development of insulin resistance, focusing on the underappreciated connections among inflammation, extracellular remodeling, cytoskeletal interactions, mitochondrial function, and insulin resistance in human skeletal muscle. Several sources of inflammation, including expansion of adipose tissue resulting in increased lipolysis and alterations in pro- and anti-inflammatory cytokines, contribute to the insulin resistance observed in obesity and type 2 diabetes. In the experimental model of lipid oversupply, an inflammatory response in skeletal muscle leads to altered expression extracellular matrix-related genes as well as nuclear encoded mitochondrial genes. A similar pattern also is observed in “naturally” occurring insulin resistance in muscle of obese nondiabetic individuals and patients with type 2 diabetes mellitus. More recently, alterations in proteins (including α-actinin-2, desmin, proteasomes, and chaperones) involved in muscle structure and function have been observed in insulin-resistant muscle. Some of these cytoskeletal proteins are mechanosignal transducers that allow muscle fibers to sense contractile activity and respond appropriately. The ensuing alterations in expression of genes coding for mitochondrial proteins and cytoskeletal proteins may contribute to the mitochondrial changes observed in insulin-resistant muscle. These changes in turn may lead to a reduction in fat oxidation and an increase in intramyocellular lipid, which contributes to the defects in insulin signaling in insulin resistance. PMID:21862724

Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells

PubMed Central

Doczi, Judit; Torocsik, Beata; Echaniz-Laguna, Andoni; Mousson de Camaret, Bénédicte; Starkov, Anatoly; Starkova, Natalia; Gál, Aniko; Molnár, Mária J; Kawamata, Hibiki; Manfredi, Giovanni; Adam-Vizi, Vera; Chinopoulos, Christos

2016-01-01

The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT’s voltage-sensing properties elicited by calcimycin or H2O2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the ‘thinness ratio’ and the ‘cobalt-calcein’ technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca2+ levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H2O2-induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient. PMID:27221760

ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells.

PubMed

Lewis, Samantha C; Uchiyama, Lauren F; Nunnari, Jodi

2016-07-15

Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, hundreds to thousands of mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis--events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids are necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria. Copyright © 2016, American Association for the Advancement of Science.

Analysis of Mitochondrial haemoglobin in Parkinson's disease brain.

PubMed

Shephard, Freya; Greville-Heygate, Oliver; Liddell, Susan; Emes, Richard; Chakrabarti, Lisa

2016-07-01

Mitochondrial dysfunction is an early feature of neurodegeneration. We have shown there are mitochondrial haemoglobin changes with age and neurodegeneration. We hypothesised that altered physiological processes are associated with recruitment and localisation of haemoglobin to these organelles. To confirm a dynamic localisation of haemoglobin we exposed Drosophila melanogaster to cyclical hypoxia with recovery. With a single cycle of hypoxia and recovery we found a relative accumulation of haemoglobin in the mitochondria compared with the cytosol. An additional cycle of hypoxia and recovery led to a significant increase of mitochondrial haemoglobin (p<0.05). We quantified ratios of human mitochondrial haemoglobin in 30 Parkinson's and matched control human post-mortem brains. Relative mitochondrial/cytosolic quantities of haemoglobin were obtained for the cortical region, substantia nigra and cerebellum. In age matched post-mortem brain mitochondrial haemoglobin ratios change, decreasing with disease duration in female cerebellum samples (n=7). The change is less discernible in male cerebellum (n=18). In cerebellar mitochondria, haemoglobin localisation in males with long disease duration shifts from the intermembrane space to the outer membrane of the organelle. These new data illustrate dynamic localisation of mitochondrial haemoglobin within the cell. Mitochondrial haemoglobin should be considered in the context of gender differences characterised in Parkinson's disease. It has been postulated that cerebellar circuitry may be activated to play a protective role in individuals with Parkinson's. The changing localisation of intracellular haemoglobin in response to hypoxia presents a novel pathway to delineate the role of the cerebellum in Parkinson's disease. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Thermal adaptation and clinal mitochondrial DNA variation of European anchovy

PubMed Central

Silva, Gonçalo; Lima, Fernando P.; Martel, Paulo; Castilho, Rita

2014-01-01

Natural populations of widely distributed organisms often exhibit genetic clinal variation over their geographical ranges. The European anchovy, Engraulis encrasicolus, illustrates this by displaying a two-clade mitochondrial structure clinally arranged along the eastern Atlantic. One clade has low frequencies at higher latitudes, whereas the other has an anti-tropical distribution, with frequencies decreasing towards the tropics. The distribution pattern of these clades has been explained as a consequence of secondary contact after an ancient geographical isolation. However, it is not unlikely that selection acts on mitochondria whose genes are involved in relevant oxidative phosphorylation processes. In this study, we performed selection tests on a fragment of 1044 bp of the mitochondrial cytochrome b gene using 455 individuals from 18 locations. We also tested correlations of six environmental features: temperature, salinity, apparent oxygen utilization and nutrient concentrations of phosphate, nitrate and silicate, on a compilation of mitochondrial clade frequencies from 66 sampling sites comprising 2776 specimens from previously published studies. Positive selection in a single codon was detected predominantly (99%) in the anti-tropical clade and temperature was the most relevant environmental predictor, contributing with 59% of the variance in the geographical distribution of clade frequencies. These findings strongly suggest that temperature is shaping the contemporary distribution of mitochondrial DNA clade frequencies in the European anchovy. PMID:25143035

Relations of mitochondrial genetic variants to measures of vascular function.

PubMed

Fetterman, Jessica L; Liu, Chunyu; Mitchell, Gary F; Vasan, Ramachandran S; Benjamin, Emelia J; Vita, Joseph A; Hamburg, Naomi M; Levy, Daniel

2018-05-01

Mitochondrial genetic variation with resultant alterations in oxidative phosphorylation may influence vascular function and contribute to cardiovascular disease susceptibility. We assessed relations of peptide-encoding variants in the mitochondrial genome with measures of vascular function in Framingham Heart Study participants. Of 258 variants assessed, 40 were predicted to have functional consequences by bioinformatics programs. A maternal pattern of heritability was estimated to contribute to the variability of aortic stiffness. A putative association with a microvascular function measure was identified that requires replication. The methods we have developed can be applied to assess the relations of mitochondrial genetic variation to other phenotypes. Copyright © 2017 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

Type 2 diabetic patients and their offspring show altered parameters of iron status, oxidative stress and genes related to mitochondrial activity.

PubMed

Le Blanc, Solange; Villarroel, Pia; Candia, Valeria; Gavilán, Natalia; Soto, Néstor; Pérez-Bravo, Francisco; Arredondo, Miguel

2012-08-01

Type 2 diabetes (T2D) is directly related to alterations in iron status, oxidative stress and decreased mitochondrial activity, but the possible interaction of these parameters among T2D patients and their offspring is unclear. The whole study included 301 subjects: 77 T2D patients and one of their offspring and 51 control subjects with one of their offspring. The offspring were older than 20 years old. We measured parameters of iron status (serum iron, ferritin and transferrin receptor), diabetes (pre and post-prandial glucose, insulin, lipids), oxidative stress (Heme oxygenase activity, TBARS, SOD, GSH, Vitamin E), as well as the expression of genes in blood leukocytes related to mitochondrial apopotosis (mitofusin and Bcl/Bax ratios). The offspring of T2D patients had increased levels of serum ferritin (P < 0.01) and lower transferrin receptor (P < 0.008); higher insulin (P < 0.03) and total and LDL cholesterol; higher heme oxygenase and SOD activities increased TBARS and lower GSH; decreased mitofusin and Bcl/Bax expression ratios compared to offspring of normal subjects. These results suggest that the offspring of T2D patients could have an increased metabolic risk of develop a cardiovascular disease mediated by oxidative stress and iron status.

Mitochondrial Aging: Is There a Mitochondrial Clock?

PubMed

Zorov, Dmitry B; Popkov, Vasily A; Zorova, Ljubava D; Vorobjev, Ivan A; Pevzner, Irina B; Silachev, Denis N; Zorov, Savva D; Jankauskas, Stanislovas S; Babenko, Valentina A; Plotnikov, Egor Y

2017-09-01

Fragmentation (fission) of mitochondria, occurring in response to oxidative challenge, leads to heterogeneity in the mitochondrial population. It is assumed that fission provides a way to segregate mitochondrial content between the "young" and "old" phenotype, with the formation of mitochondrial "garbage," which later will be disposed. Fidelity of this process is the basis of mitochondrial homeostasis, which is disrupted in pathological conditions and aging. The asymmetry of the mitochondrial fission is similar to that of their evolutionary ancestors, bacteria, which also undergo an aging process. It is assumed that mitochondrial markers of aging are recognized by the mitochondrial quality control system, preventing the accumulation of dysfunctional mitochondria, which normally are subjected to disposal. Possibly, oncocytoma, with its abnormal proliferation of mitochondria occupying the entire cytoplasm, represents the case when segregation of damaged mitochondria is impaired during mitochondrial division. It is plausible that mitochondria contain a "clock" which counts the degree of mitochondrial senescence as the extent of flagging (by ubiquitination) of damaged mitochondria. Mitochondrial aging captures the essence of the systemic aging which must be analyzed. We assume that the mitochondrial aging mechanism is similar to the mechanism of aging of the immune system which we discuss in detail. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Trimetazidine prevents palmitate-induced mitochondrial fission and dysfunction in cultured cardiomyocytes.

PubMed

Kuzmicic, Jovan; Parra, Valentina; Verdejo, Hugo E; López-Crisosto, Camila; Chiong, Mario; García, Lorena; Jensen, Michael D; Bernlohr, David A; Castro, Pablo F; Lavandero, Sergio

2014-10-01

Metabolic and cardiovascular disease patients have increased plasma levels of lipids and, specifically, of palmitate, which can be toxic for several tissues. Trimetazidine (TMZ), a partial inhibitor of lipid oxidation, has been proposed as a metabolic modulator for several cardiovascular pathologies. However, its mechanism of action is controversial. Given the fact that TMZ is able to alter mitochondrial metabolism, we evaluated the protective role of TMZ on mitochondrial morphology and function in an in vitro model of lipotoxicity induced by palmitate. We treated cultured rat cardiomyocytes with BSA-conjugated palmitate (25 nM free), TMZ (0.1-100 μM), or a combination of both. We evaluated mitochondrial morphology and lipid accumulation by confocal fluorescence microscopy, parameters of mitochondrial metabolism (mitochondrial membrane potential, oxygen consumption rate [OCR], and ATP levels), and ceramide production by mass spectrometry and indirect immunofluorescence. Palmitate promoted mitochondrial fission evidenced by a decrease in mitochondrial volume (50%) and an increase in the number of mitochondria per cell (80%), whereas TMZ increased mitochondrial volume (39%), and decreased mitochondrial number (56%), suggesting mitochondrial fusion. Palmitate also decreased mitochondrial metabolism (ATP levels and OCR), while TMZ potentiated all the metabolic parameters assessed. Moreover, pretreatment with TMZ protected the cardiomyocytes from palmitate-induced mitochondrial fission and dysfunction. TMZ also increased lipid accumulation in cardiomyocytes, and prevented palmitate-induced ceramide production. Our data show that TMZ protects cardiomyocytes by changing intracellular lipid management. Thus, the beneficial effects of TMZ on patients with different cardiovascular pathologies can be related to modulation of the mitochondrial morphology and function. Copyright © 2014 Elsevier Inc. All rights reserved.

Cofilin1-dependent actin dynamics control DRP1-mediated mitochondrial fission

PubMed Central

Rehklau, Katharina; Hoffmann, Lena; Gurniak, Christine B; Ott, Martin; Witke, Walter; Scorrano, Luca; Culmsee, Carsten; Rust, Marco B

2017-01-01

Mitochondria form highly dynamic networks in which organelles constantly fuse and divide. The relevance of mitochondrial dynamics is evident from its implication in various human pathologies, including cancer or neurodegenerative, endocrine and cardiovascular diseases. Dynamin-related protein 1 (DRP1) is a key regulator of mitochondrial fission that oligomerizes at the mitochondrial outer membrane and hydrolyzes GTP to drive mitochondrial fragmentation. Previous studies demonstrated that DRP1 recruitment and mitochondrial fission is promoted by actin polymerization at the mitochondrial surface, controlled by the actin regulatory proteins inverted formin 2 (INF2) and Spire1C. These studies suggested the requirement of additional actin regulatory activities to control DRP1-mediated mitochondrial fission. Here we show that the actin-depolymerizing protein cofilin1, but not its close homolog actin-depolymerizing factor (ADF), is required to maintain mitochondrial morphology. Deletion of cofilin1 caused mitochondrial DRP1 accumulation and fragmentation, without altering mitochondrial function or other organelles’ morphology. Mitochondrial morphology in cofilin1-deficient cells was restored upon (i) re-expression of wild-type cofilin1 or a constitutively active mutant, but not of an actin-binding-deficient mutant, (ii) pharmacological destabilization of actin filaments and (iii) genetic depletion of DRP1. Our work unraveled a novel function for cofilin1-dependent actin dynamics in mitochondrial fission, and identified cofilin1 as a negative regulator of mitochondrial DRP1 activity. We conclude that cofilin1 is required for local actin dynamics at mitochondria, where it may balance INF2/Spire1C-induced actin polymerization. PMID:28981113

Mitochondrial phylogeography of a Beringian relict: the endemic freshwater genus of blackfish Dallia (Esociformes).

PubMed

Campbell, M A; Lopéz, J A

2014-02-01

Mitochondrial genetic variability among populations of the blackfish genus Dallia (Esociformes) across Beringia was examined. Levels of divergence and patterns of geographic distribution of mitochondrial DNA lineages were characterized using phylogenetic inference, median-joining haplotype networks, Bayesian skyline plots, mismatch analysis and spatial analysis of molecular variance (SAMOVA) to infer genealogical relationships and to assess patterns of phylogeography among extant mitochondrial lineages in populations of species of Dallia. The observed variation includes extensive standing mitochondrial genetic diversity and patterns of distinct spatial segregation corresponding to historical and contemporary barriers with minimal or no mixing of mitochondrial haplotypes between geographic areas. Mitochondrial diversity is highest in the common delta formed by the Yukon and Kuskokwim Rivers where they meet the Bering Sea. Other regions sampled in this study host comparatively low levels of mitochondrial diversity. The observed levels of mitochondrial diversity and the spatial distribution of that diversity are consistent with persistence of mitochondrial lineages in multiple refugia through the last glacial maximum. © 2014 The Fisheries Society of the British Isles.

Mitochondrial transcription factor A (Tfam) gene sequencing and mitochondrial evaluation in inherited retinal dysplasia in miniature schnauzer dogs

PubMed Central

Bauer, Bianca S.; Forsyth, George W.; Sandmeyer, Lynne S.; Grahn, Bruce H.

2011-01-01

Mitochondrial transcription factor A (Tfam) has been implicated in the pathogenesis of retinal dysplasia in miniature schnauzer dogs and it has been proposed that affected dogs have altered mitochondrial numbers, size, and morphology. To test these hypotheses the Tfam gene of affected and normal miniature schnauzer dogs with retinal dysplasia was sequenced and lymphocyte mitochondria were quantified, measured, and the morphology was compared in normal and affected dogs using transmission electron microscopy. For Tfam sequencing, retina, retinal pigment epithelium (RPE), and whole blood samples were collected. Total RNA was isolated from the retina and RPE and reverse transcribed to make cDNA. Genomic DNA was extracted from white blood cell pellets obtained from the whole blood samples. The Tfam coding sequence, 5′ promoter region, intron1 and the 3′ non-coding sequence of normal and affected dogs were amplified using polymerase chain reaction (PCR), cloned and sequenced. For electron microscopy, lymphocytes from affected and normal dogs were photographed and the mitochondria within each cross-section were identified, quantified, and the mitochondrial area (μm2) per lymphocyte cross-section was calculated. Lastly, using a masked technique, mitochondrial morphology was compared between the 2 groups. Sequencing of the miniature schnauzer Tfam gene revealed no functional sequence variation between affected and normal dogs. Lymphocyte and mitochondrial area, mitochondrial quantification, and morphology assessment also revealed no significant difference between the 2 groups. Further investigation into other candidate genes or factors causing retinal dysplasia in the miniature schnauzer is warranted. PMID:21731185

Diversity of the Arabidopsis mitochondrial genome occurs via nuclear-controlled recombination activity.

PubMed

Arrieta-Montiel, Maria P; Shedge, Vikas; Davila, Jaime; Christensen, Alan C; Mackenzie, Sally A

2009-12-01

The plant mitochondrial genome is recombinogenic, with DNA exchange activity controlled to a large extent by nuclear gene products. One nuclear gene, MSH1, appears to participate in suppressing recombination in Arabidopsis at every repeated sequence ranging in size from 108 to 556 bp. Present in a wide range of plant species, these mitochondrial repeats display evidence of successful asymmetric DNA exchange in Arabidopsis when MSH1 is disrupted. Recombination frequency appears to be influenced by repeat sequence homology and size, with larger size repeats corresponding to increased DNA exchange activity. The extensive mitochondrial genomic reorganization of the msh1 mutant produced altered mitochondrial transcription patterns. Comparison of mitochondrial genomes from the Arabidopsis ecotypes C24, Col-0, and Ler suggests that MSH1 activity accounts for most or all of the polymorphisms distinguishing these genomes, producing ecotype-specific stoichiometric changes in each line. Our observations suggest that MSH1 participates in mitochondrial genome evolution by influencing the lineage-specific pattern of mitochondrial genetic variation in higher plants.

A high throughput respirometric assay for mitochondrial biogenesis and toxicity

PubMed Central

Beeson, Craig C.; Beeson, Gyda C.; Schnellmann, Rick G.

2010-01-01

Mitochondria are a common target of toxicity for drugs and other chemicals, and results in decreased aerobic metabolism and cell death. In contrast, mitochondrial biogenesis restores cell vitality and there is a need for new agents to induce biogenesis. Current cell-based models of mitochondrial biogenesis or toxicity are inadequate because cultured cell lines are highly glycolytic with minimal aerobic metabolism and altered mitochondrial physiology. In addition, there are no high-throughput, real-time assays that assess mitochondrial function. We adapted primary cultures of renal proximal tubular cells (RPTC) that exhibit in vivo levels of aerobic metabolism, are not glycolytic, and retain higher levels of differentiated functions and used the Seahorse Biosciences analyzer to measure mitochondrial function in real time in multi-well plates. Using uncoupled respiration as a marker of electron transport chain (ETC) integrity, the nephrotoxicants cisplatin, HgCl2 and gentamicin exhibited mitochondrial toxicity prior to decreases in basal respiration and cell death. Conversely, using FCCP-uncoupled respiration as a marker of maximal ETC activity, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), SRT1720, resveratrol, daidzein, and metformin produced mitochondrial biogenesis in RPTC. The merger of the RPTC model and multi-well respirometry results in a single high throughput assay to measure mitochondrial biogenesis and toxicity, and nephrotoxic potential. PMID:20465991

MicroRNA as biomarkers of mitochondrial toxicity

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

Baumgart, Bethany R., E-mail: bethany.baumgart@bms

Mitochondrial toxicity can be difficult to detect as most cells can tolerate reduced activity as long as minimal capacity for function is maintained. However, once minimal capacity is lost, apoptosis or necrosis occurs quickly. Identification of more sensitive, early markers of mitochondrial toxicity was the objective of this work. Rotenone, a mitochondrial complex I inhibitor, and 3-nitropropionic acid (3-NP), a mitochondrial complex II inhibitor, were administered daily to male Sprague–Dawley rats at subcutaneous doses of 0.1 or 0.3 mg/kg/day and intraperitoneal doses of 5 or 10 mg/kg/day, respectively, for 1 week. Samples of kidney, skeletal muscle (quadriceps femoris), and serummore » were collected for analysis of mitochondrial DNA (mtDNA) copy number and microRNA (miRNA) expression patterns. MtDNA was significantly decreased with administration of rotenone at 0.3 mg/kg/day and 3-NP at 5 and 10 mg/kg/day in the quadriceps femoris and with 3-NP at 10 mg/kg/day in the kidney. Additionally, rotenone and 3-NP treatment produced changes to miRNA expression that were similar in direction (i.e. upregulation, downregulation) to those previously linked to mitochondrial functions, such as mitochondrial damage and biogenesis (miR-122, miR-202-3p); regulation of ATP synthesis, abolished oxidative phosphorylation, and loss of membrane potential due to increased reactive oxygen species (ROS) production (miR-338-5p, miR-546, miR-34c); and mitochondrial DNA damage and depletion (miR-546). These results suggest that miRNAs may be sensitive biomarkers for early detection of mitochondrial toxicity. - Highlights: • MtDNA decreased after treatment with respiratory chain inhibitors rotenone and 3-NP. • Decrease in mtDNA is generally dose-related and indicative of mitochondrial toxicity. • Altered miRNA has reported roles in regulating mitochondrial function. • Induction of miR-338-5p in kidney and serum suggests potential as renal biomarker. • Induction of miR-122

Mitochondrial nucleoid clusters protect newly synthesized mtDNA during Doxorubicin- and Ethidium Bromide-induced mitochondrial stress

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

Alán, Lukáš, E-mail: lukas.alan@fgu.cas.cz; Špaček

Mitochondrial DNA (mtDNA) is compacted in ribonucleoprotein complexes called nucleoids, which can divide or move within the mitochondrial network. Mitochondrial nucleoids are able to aggregate into clusters upon reaction with intercalators such as the mtDNA depletion agent Ethidium Bromide (EB) or anticancer drug Doxorobicin (DXR). However, the exact mechanism of nucleoid clusters formation remains unknown. Resolving these processes may help to elucidate the mechanisms of DXR-induced cardiotoxicity. Therefore, we addressed the role of two key nucleoid proteins; mitochondrial transcription factor A (TFAM) and mitochondrial single-stranded binding protein (mtSSB); in the formation of mitochondrial nucleoid clusters during the action of intercalators.more » We found that both intercalators cause numerous aberrations due to perturbing their native status. By blocking mtDNA replication, both agents also prevented mtDNA association with TFAM, consequently causing nucleoid aggregation into large nucleoid clusters enriched with TFAM, co-existing with the normal nucleoid population. In the later stages of intercalation (> 48 h), TFAM levels were reduced to 25%. In contrast, mtSSB was released from mtDNA and freely distributed within the mitochondrial network. Nucleoid clusters mostly contained nucleoids with newly replicated mtDNA, however the nucleoid population which was not in replication mode remained outside the clusters. Moreover, the nucleoid clusters were enriched with p53, an anti-oncogenic gatekeeper. We suggest that mitochondrial nucleoid clustering is a mechanism for protecting nucleoids with newly replicated DNA against intercalators mediating genotoxic stress. These results provide new insight into the common mitochondrial response to mtDNA stress and can be implied also on DXR-induced mitochondrial cytotoxicity. - Highlights: • The mechanism for mitochondrial nucleoid clustering is proposed. • DNA intercalators (Doxorubicin or Ethidium Bromide) prevent

Gradual changes in permeability of inner mitochondrial membrane precede the mitochondrial permeability transition.

PubMed

Balakirev, M Y; Zimmer, G

1998-08-01

Some compounds are known to induce solute-nonselective permeability of the inner mitochondrial membrane (IMM) in Ca2+-loaded mitochondria. Existing data suggest that this process, following the opening of a mitochondrial permeability transition pore, is preceded by different solute-selective permeable states of IMM. At pH 7, for instance, the K0.5 for Ca2+-induced pore opening is 16 microM, a value 80-fold above a therapeutically relevant shift of intracellular Ca2+ during ischemia in vivo. The present work shows that in the absence of Ca2+, phenylarsine oxide and tetraalkyl thiuram disulfides (TDs) are able to induce a complex sequence of IMM permeability changes. At first, these agents activated an electrogenic K+ influx into the mitochondria. This K+-specific pathway had K0.5 = 35 mM for K+ and was inhibited by bromsulfalein with Ki = 2.5 microM. The inhibitors of mitochondrial KATP channel, ATP and glibenclamide, did not inhibit K+ transport via this pathway. Moreover, 50 microM glibenclamide induced by itself K+ influx into the mitochondria. After the increase in K+ permeability of IMM, mitochondria become increasingly permeable to protons. Mechanisms of H+ leak and nonselective permeability increase could also be different depending on the type of mitochondrial permeability transition (MPT) inducer. Thus, permeabilization of mitochondria induced by phenylarsine oxide was fully prevented by ADP and/or cyclosporin A, whereas TD-induced membrane alterations were insensitive toward these inhibitors. It is suggested that MPT in vivo leading to irreversible apoptosis is irrelevant in reversible ischemia/reperfusion injury. Copyright 1998 Academic Press.

Characterization of canine mitochondrial protein expression in natural and induced forms of idiopathic dilated cardiomyopathy.

PubMed

Lopes, Rosana; Solter, Philip F; Sisson, D David; Oyama, Mark A; Prosek, Robert

2006-06-01

To map canine mitochondrial proteins and identify qualitative and quantitative differences in heart mitochondrial protein expression between healthy dogs and dogs with naturally occurring and induced dilated cardiomyopathy (DCM). Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with induced DCM. Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by >or= 2-fold between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. Within narrow pH gradients of control canine heart mitochondrial samples, a total of 1,528 protein spots were revealed. Forty subunits of heart mitochondrial proteins that differ significantly from control tissues were altered in tissue specimens from dogs with naturally occurring and induced forms of DCM. The most affected heart mitochondrial proteins in both groups were those of oxidative phosphorylation (55%). Upregulation of manganese superoxide dismutase was suggestive of heart oxidative injury in tissue specimens from dogs with both forms of DCM. Evidence of apoptosis was associated with overexpression of the heart mitochondrial voltage-dependent anion channel-2 protein and endonuclease G in tissue specimens from dogs with induced DCM. Alterations of heart mitochondrial proteins related to oxidative phosphorylation dysfunction were more prevalent in tissue specimens from dogs with induced or naturally occurring DCM, compared with those of control dogs.

Mitochondrial Function in Sepsis

PubMed Central

Arulkumaran, Nishkantha; Deutschman, Clifford S.; Pinsky, Michael R.; Zuckerbraun, Brian; Schumacker, Paul T.; Gomez, Hernando; Gomez, Alonso; Murray, Patrick; Kellum, John A.

2015-01-01

Mitochondria are an essential part of the cellular infrastructure, being the primary site for high energy adenosine triphosphate (ATP) production through oxidative phosphorylation. Clearly, in severe systemic inflammatory states, like sepsis, cellular metabolism is usually altered and end organ dysfunction not only common but predictive of long term morbidity and mortality. Clearly, interest is mitochondrial function both as a target for intracellular injury and response to extrinsic stress have been a major focus of basic science and clinical research into the pathophysiology of acute illness. However, mitochondria have multiple metabolic and signaling functions that may be central in both the expression of sepsis and its ultimate outcome. In this review, the authors address five primary questions centered on the role of mitochondria in sepsis. This review should be used as both a summary source in placing mitochondrial physiology within the context of acute illness and as a focal point for addressing new research into diagnostic and treatment opportunities these insights provide. PMID:26871665

MITOCHONDRIAL FUNCTION IN SEPSIS.

PubMed

Arulkumaran, Nishkantha; Deutschman, Clifford S; Pinsky, Michael R; Zuckerbraun, Brian; Schumacker, Paul T; Gomez, Hernando; Gomez, Alonso; Murray, Patrick; Kellum, John A

2016-03-01

Mitochondria are an essential part of the cellular infrastructure, being the primary site for high-energy adenosine triphosphate production through oxidative phosphorylation. Clearly, in severe systemic inflammatory states, like sepsis, cellular metabolism is usually altered, and end organ dysfunction is not only common, but also predictive of long-term morbidity and mortality. Clearly, interest is mitochondrial function both as a target for intracellular injury and response to extrinsic stress have been a major focus of basic science and clinical research into the pathophysiology of acute illness. However, mitochondria have multiple metabolic and signaling functions that may be central in both the expression of sepsis and its ultimate outcome. In this review, the authors address five primary questions centered on the role of mitochondria in sepsis. This review should be used both as a summary source in placing mitochondrial physiology within the context of acute illness and as a focal point for addressing new research into diagnostic and treatment opportunities these insights provide.

Optic neuropathies--importance of spatial distribution of mitochondria as well as function.

PubMed

Yu Wai Man, C Y; Chinnery, P F; Griffiths, P G

2005-01-01

death. Evidence for this comes from studies of cultured cells with the dominant optic atrophy mutation in which mitochondrial distribution is altered and from some forms of hereditary spastic paraparesis which are associated with optic atrophy. The responsible mutations do not affect ATP production until late in the disease but do affect mitochondrial arrangement, again showing that mitochondrial distribution as well as energy production by individual mitochondria may be important in the pathogenesis of ganglion cell death. Greater understanding of the factors localising mitochondria within the ganglion cell axon in particular the interaction with cytoskeleton is required to formulate new treatments. Boosting energy production alone may not be an effective treatment.

The Roles of Mitochondrial Damage-Associated Molecular Patterns in Diseases

PubMed Central

Nakahira, Kiichi; Hisata, Shu

2015-01-01

Abstract Significance: Mitochondria, vital cellular power plants to generate energy, are involved in immune responses. Mitochondrial damage-associated molecular patterns (DAMPs) are molecules that are released from mitochondria to extracellular space during cell death and include not only proteins but also DNA or lipids. Mitochondrial DAMPs induce inflammatory responses and are critically involved in the pathogenesis of various diseases. Recent Advances: Recent studies elucidate the molecular mechanisms by which mitochondrial DAMPs are released and initiate immune responses by use of genetically modulated cells or animals. Importantly, the levels of mitochondrial DAMPs in patients are often associated with severity and prognosis of human diseases, such as infection, asthma, ischemic heart disease, and cancer. Critical Issues: Although mitochondrial DAMPs can represent proinflammatory molecules in various experimental models, their roles in human diseases may be multifunctional and complex. It remains unclear where and how mitochondrial DAMPs are liberated into extracellular spaces and exert their biological functions particularly in vivo. In addition, while mitochondria can secrete several types of DAMPs during cell death, the interaction of each mitochondrial DAMP (e.g., synergistic effects) remains unclear. Future Directions: Regulation of mitochondrial DAMP-mediated immune responses may be important to alter the progression of human diseases. In addition, measuring mitochondrial DAMPs in patients may be clinically useful as biomarkers to predict prognosis or response to therapies. Further studies of the mechanisms by which mitochondrial DAMPs impact the initiation and progression of diseases may lead to the development of therapeutics specifically targeting this pathway. Antioxid. Redox Signal. 23, 1329–1350. PMID:26067258

Targeting mitochondria by Zn(II)N-alkylpyridylporphyrins: the impact of compound sub-mitochondrial partition on cell respiration and overall photodynamic efficacy.

PubMed

Odeh, Ahmad M; Craik, James D; Ezzeddine, Rima; Tovmasyan, Artak; Batinic-Haberle, Ines; Benov, Ludmil T

2014-01-01

Mitochondria play a key role in aerobic ATP production and redox control. They harness crucial metabolic pathways and control cell death mechanisms, properties that make these organelles essential for survival of most eukaryotic cells. Cancer cells have altered cell death pathways and typically show a shift towards anaerobic glycolysis for energy production, factors which point to mitochondria as potential culprits in cancer development. Targeting mitochondria is an attractive approach to tumor control, but design of pharmaceutical agents based on rational approaches is still not well established. The aim of this study was to investigate which structural features of specially designed Zn(II)N-alkylpyridylporphyrins would direct them to mitochondria and to particular mitochondrial targets. Since Zn(II)N-alkylpyridylporphyrins can act as highly efficient photosensitizers, their localization can be confirmed by photodamage to particular mitochondrial components. Using cultured LS174T adenocarcinoma cells, we found that subcellular distribution of Zn-porphyrins is directed by the nature of the substituents attached to the meso pyridyl nitrogens at the porphyrin ring. Increasing the length of the aliphatic chain from one carbon (methyl) to six carbons (hexyl) increased mitochondrial uptake of the compounds. Such modifications also affected sub-mitochondrial distribution of the Zn-porphyrins. The amphiphilic hexyl derivative (ZnTnHex-2-PyP) localized in the vicinity of cytochrome c oxidase complex, causing its inactivation during illumination. Photoinactivation of critical cellular targets explains the superior efficiency of the hexyl derivative in causing mitochondrial photodamage, and suppressing cellular respiration and survival. Design of potent photosensitizers and redox-active scavengers of free radicals should take into consideration not only selective organelle uptake and localization, but also selective targeting of critical macromolecular structures.

Multifractal magnetic susceptibility distribution models of hydrothermally altered rocks in the Needle Creek Igneous Center of the Absaroka Mountains, Wyoming

USGS Publications Warehouse

Gettings, M.E.

2005-01-01

Magnetic susceptibility was measured for 700 samples of drill core from thirteen drill holes in the porphyry copper-molybdenum deposit of the Stinkingwater mining district in the Absaroka Mountains, Wyoming. The magnetic susceptibility measurements, chemical analyses, and alteration class provided a database for study of magnetic susceptibility in these altered rocks. The distribution of the magnetic susceptibilities for all samples is multi-modal, with overlapping peaked distributions for samples in the propylitic and phyllic alteration class, a tail of higher susceptibilities for potassic alteration, and an approximately uniform distribution over a narrow range at the highest susceptibilities for unaltered rocks. Samples from all alteration and mineralization classes show susceptibilities across a wide range of values. Samples with secondary (supergene) alteration due to oxidation or enrichment show lower susceptibilities than primary (hypogene) alteration rock. Observed magnetic susceptibility variations and the monolithological character of the host rock suggest that the variations are due to varying degrees of alteration of blocks of rock between fractures that conducted hydrothermal fluids. Alteration of rock from the fractures inward progressively reduces the bulk magnetic susceptibility of the rock. The model introduced in this paper consists of a simulation of the fracture pattern and a simulation of the alteration of the rock between fractures. A multifractal model generated from multiplicative cascades with unequal ratios produces distributions statistically similar to the observed distributions. The reduction in susceptibility in the altered rocks was modelled as a diffusion process operating on the fracture distribution support. The average magnetic susceptibility was then computed for each block. For the purpose of comparing the model results with observation, the simulated magnetic susceptibilities were then averaged over the same interval as the

Developmental Exposure to Second-Hand Smoke Increases Adult Atherogenesis and Alters Mitochondrial DNA Copy Number and Deletions in apoE−/− Mice

PubMed Central

Fetterman, Jessica L.; Pompilius, Melissa; Westbrook, David G.; Uyeminami, Dale; Brown, Jamelle; Pinkerton, Kent E.; Ballinger, Scott W.

2013-01-01

Cardiovascular disease is a major cause of morbidity and mortality in the United States. While many studies have focused upon the effects of adult second-hand smoke exposure on cardiovascular disease development, disease development occurs over decades and is likely influenced by childhood exposure. The impacts of in utero versus neonatal second-hand smoke exposure on adult atherosclerotic disease development are not known. The objective of the current study was to determine the effects of in utero versus neonatal exposure to a low dose (1 mg/m3 total suspended particulate) of second-hand smoke on adult atherosclerotic lesion development using the apolipoprotein E null mouse model. Consequently, apolipoprotein E null mice were exposed to either filtered air or second-hand smoke: (i) in utero from gestation days 1–19, or (ii) from birth until 3 weeks of age (neonatal). Subsequently, all animals were exposed to filtered air and sacrificed at 12–14 weeks of age. Oil red-O staining of whole aortas, measures of mitochondrial damage, and oxidative stress were performed. Results show that both in utero and neonatal second-hand smoke exposure significantly increased adult atherogenesis in mice compared to filtered air controls. These changes were associated with changes in aconitase and mitochondrial superoxide dismutase activities consistent with increased oxidative stress in the aorta, changes in mitochondrial DNA copy number and deletion levels. These studies show that in utero or neonatal exposure to second-hand smoke significantly influences adult atherosclerotic lesion development and results in significant alterations to the mitochondrion and its genome that may contribute to atherogenesis. PMID:23825571

Fourier analysis of mitochondrial distribution in oocytes

NASA Astrophysics Data System (ADS)

Hollmann, Joseph L.; Brooks, Dana H.; Newmark, Judith A.; Warner, Carol M.; DiMarzio, Charles A.

2011-03-01

This paper describes a novel approach to quantifying mitochondrial patterns which are typically described using the qualitative terms "diffuse" "aggregated" and are potentially key indicators for an oocyte's health and survival potential post-implantation. An oocyte was isolated in a confocal image and a coarse grid was superimposed upon it. The spatial spectrum was calculated and an aggregation factor was generated. A classifier for healthy cells was developed and verified. The aggregation factor showed a clear distinction between the healthy and unhealthy oocytes. The ultimate goal is to screen oocytes for viability preimplantation, thus improving the outcome of in vitro fertilization (IVF) treatments.

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.

Mitochondrial deficits and abnormal mitochondrial retrograde axonal transport play a role in the pathogenesis of mutant Hsp27-induced Charcot Marie Tooth Disease

PubMed Central

Innes, Amy; Wanisch, Klaus; Kolaszynska, Alicia Koyen; Pandraud, Amelie; Kelly, Gavin; Abramov, Andrey Y.; Reilly, Mary M.; Schiavo, Giampietro; Greensmith, Linda

2017-01-01

Abstract Mutations in the small heat shock protein Hsp27, encoded by the HSPB1 gene, have been shown to cause Charcot Marie Tooth Disease type 2 (CMT-2) or distal hereditary motor neuropathy (dHMN). Protein aggregation and axonal transport deficits have been implicated in the disease. In this study, we conducted analysis of bidirectional movements of mitochondria in primary motor neuron axons expressing wild type and mutant Hsp27. We found significantly slower retrograde transport of mitochondria in Ser135Phe, Pro39Leu and Arg140Gly mutant Hsp27 expressing motor neurons than in wild type Hsp27 neurons, although anterograde movement velocities remained normal. Retrograde transport of other important cargoes, such as the p75 neurotrophic factor receptor was minimally altered in mutant Hsp27 neurons, implicating that axonal transport deficits primarily affect mitochondria and the axonal transport machinery itself is less affected. Investigation of mitochondrial function revealed a decrease in mitochondrial membrane potential in mutant Hsp27 expressing motor axons, as well as a reduction in mitochondrial complex 1 activity, increased vulnerability of mitochondria to mitochondrial stressors, leading to elevated superoxide release and reduced mitochondrial glutathione (GSH) levels, although cytosolic GSH remained normal. This mitochondrial redox imbalance in mutant Hsp27 motor neurons is likely to cause low level of oxidative stress, which in turn will contribute to, and indeed may be the underlying cause of the deficits in mitochondrial axonal transport. Together, these findings suggest that the mitochondrial abnormalities in mutant Hsp27-induced neuropathies may be a primary cause of pathology, leading to further deficits in the mitochondrial axonal transport and onset of disease. PMID:28595321

Oxidative stress induces mitochondrial dysfunction in a subset of autistic lymphoblastoid cell lines

PubMed Central

Rose, S; Frye, R E; Slattery, J; Wynne, R; Tippett, M; Melnyk, S; James, S J

2014-01-01

There is an increasing recognition that mitochondrial dysfunction is associated with autism spectrum disorders. However, little attention has been given to the etiology of mitochondrial dysfunction and how mitochondrial abnormalities might interact with other physiological disturbances such as oxidative stress. Reserve capacity is a measure of the ability of the mitochondria to respond to physiological stress. In this study, we demonstrate, for the first time, that lymphoblastoid cell lines (LCLs) derived from children with autistic disorder (AD) have an abnormal mitochondrial reserve capacity before and after exposure to reactive oxygen species (ROS). Ten (44%) of 22 AD LCLs exhibited abnormally high reserve capacity at baseline and a sharp depletion of reserve capacity when challenged with ROS. This depletion of reserve capacity was found to be directly related to an atypical simultaneous increase in both proton-leak respiration and adenosine triphosphate-linked respiration in response to increased ROS in this AD LCL subgroup. In this AD LCL subgroup, 48-hour pretreatment with N-acetylcysteine, a glutathione precursor, prevented these abnormalities and improved glutathione metabolism, suggesting a role for altered glutathione metabolism associated with this type of mitochondrial dysfunction. The results of this study suggest that a significant subgroup of AD children may have alterations in mitochondrial function, which could render them more vulnerable to a pro-oxidant microenvironment as well as intrinsic and extrinsic sources of ROS such as immune activation and pro-oxidant environmental toxins. These findings are consistent with the notion that AD is caused by a combination of genetic and environmental factors. PMID:24690598

Role of mitochondrial permeability transition pores in mitochondrial autophagy.

PubMed

Rodriguez-Enriquez, Sara; He, Lihua; Lemasters, John J

2004-12-01

During autophagy, cells rid themselves of damaged and superfluous mitochondria, as well as other organelles. This activation of mitochondrial turnover could be the result of changes in the physiological state of mitochondria. Confocal microscopy and fluorescence techniques indicate that onset of mitochondrial permeability transition is one such change. The mitochondrial permeability transition is a reversible phenomenon whereby the mitochondrial inner membrane becomes freely permeable to solutes of less than 1500 Da. At onset of the mitochondrial permeability transition, mitochondria depolarize, uncouple, and undergo large amplitude swelling due to opening of permeability transition pores, which may form by aggregation of damaged, misfolded membrane proteins. When injurious cellular stresses occur, cells may protect themselves using autophagy to remove damaged mitochondria and mutated mitochondrial DNA. Ca(2+) overloading, reactive oxygen and nitrogen species, decreased mitochondrial membrane potential, and oxidation of pyridine nucleotides and glutathione all promote mitochondrial damage and onset of the mitochondrial permeability transition. The mitochondrial permeability transition is also associated with necrosis and apoptosis after a variety of stimuli. This review emphasizes the role of the mitochondrial permeability transition as a key event in mitochondrial autophagy.

Hepatic mitochondrial energetics during catch-up fat with high-fat diets rich in lard or safflower oil.

PubMed

Crescenzo, Raffaella; Bianco, Francesca; Falcone, Italia; Tsalouhidou, Sofia; Yepuri, Gayathri; Mougios, Vassilis; Dulloo, Abdul G; Liverini, Giovanna; Iossa, Susanna

2012-09-01

We have investigated whether altered hepatic mitochondrial energetics could explain the differential effects of high-fat diets with low or high ω6 polyunsaturated fatty acid content (lard vs. safflower oil) on the efficiency of body fat recovery (catch-up fat) during refeeding after caloric restriction. After 2 weeks of caloric restriction, rats were isocalorically refed with a low-fat diet (LF) or high-fat diets made from either lard or safflower oil for 1 week, and energy balance and body composition changes were assessed. Hepatic mitochondrial energetics were determined from measurements of liver mitochondrial mass, respiratory capacities, and proton leak. Compared to rats refed the LF, the groups refed high-fat diets showed lower energy expenditure and increased efficiency of fat gain; these differences were less marked with high-safflower oil than with high-lard diet. The increase in efficiency of catch-up fat by the high-fat diets could not be attributed to differences in liver mitochondrial activity. By contrast, the lower fat gain with high-safflower oil than with high-lard diet is accompanied by higher mitochondrial proton leak and increased proportion of arachidonic acid in mitochondrial membranes. In conclusion, the higher efficiency for catch-up fat on high-lard diet than on LF cannot be explained by altered hepatic mitochondrial energetics. By contrast, the ability of the high-safflower oil diet to produce a less pronounced increase in the efficiency of catch-up fat may partly reside in increased incorporation of arachidonic acid in hepatic mitochondrial membranes, leading to enhanced proton leak and mitochondrial uncoupling.

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

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.

Mitochondrial DNA replication, nucleoside reverse-transcriptase inhibitors, and AIDS cardiomyopathy.

PubMed

Lewis, William

2003-01-01

Nucleoside reverse-transcriptase inhibitors (NRTIs) in combination with other antiretrovirals (HAART) are the cornerstones of current AIDS therapy, but extensive use brought mitochondrial side effects to light. Clinical experience, pharmacological, cell, and molecular biological evidence links altered mitochondrial (mt-) DNA replication to the toxicity of NRTIs in many tissues, and conversely, mtDNA replication defects and mtDNA depletion in target tissues are observed. Organ-specific pathological changes or diverse systemic effects result from and are frequently attributed to HAART in which NRTIs are included. The shared features of mtDNA depletion and energy depletion became key observations and related the clinical and in vivo experimental findings to inhibition of mtDNA replication by NRTI triphosphates in vitro. Subsequent to those findings, other observations suggested that mitochondrial energy deprivation is concomitant with or the result of mitochondrial oxidative stress in AIDS (from HIV, for example) or from NRTI therapy itself. Copyright 2003, Elsevier Science (USA)

Resveratrol stimulates mitochondrial fusion by a mechanism requiring mitofusin-2.

PubMed

Robb, Ellen L; Moradi, Fereshteh; Maddalena, Lucas A; Valente, Andrew J F; Fonseca, Joao; Stuart, Jeffrey A

2017-04-01

Resveratrol (RES) is a plant-derived stilbene associated with a wide range of health benefits. Mitochondria are a key downstream target of RES, and in some cell types RES promotes mitochondrial biogenesis, altered cellular redox status, and a shift toward oxidative metabolism. Mitochondria exist as a dynamic network that continually remodels via fusion and fission processes, and the extent of fusion is related to cellular redox status and metabolism. We investigated RES's effects on mitochondrial network morphology in several cell lines using a quantitative approach to measure the extent of network fusion. 48 h continuous treatment with 10-20 μM RES stimulated mitochondrial fusion in C2C12 myoblasts, PC3 cancer cells, and mouse embryonic fibroblasts stimulated significant increases in fusion in all instances, resulting in larger and more highly branched mitochondrial networks. Mitofusin-2 (Mfn2) is a key protein facilitating mitochondrial fusion, and its expression was also stimulated by RES. Using Mfn2-null cells we demonstrated that RES's effects on mitochondrial fusion, cellular respiration rates, and cell growth are all dependent upon the presence of Mfn2. Taken together, these results demonstrate that Mfn2 and mitochondrial fusion are affected by RES in ways that appear to relate to RES's known effects on cellular metabolism and growth. Copyright © 2017 Elsevier Inc. All rights reserved.

Integrated 'omics analysis reveals new drug-induced mitochondrial perturbations in human hepatocytes.

PubMed

Wolters, Jarno E J; van Breda, Simone G J; Grossmann, Jonas; Fortes, Claudia; Caiment, Florian; Kleinjans, Jos C S

2018-06-01

We performed a multiple 'omics study by integrating data on epigenomic, transcriptomic, and proteomic perturbations associated with mitochondrial dysfunction in primary human hepatocytes caused by the liver toxicant valproic acid (VPA), to deeper understand downstream events following epigenetic alterations in the mitochondrial genome. Furthermore, we investigated persistence of cross-omics changes after terminating drug treatment. Upon transient methylation changes of mitochondrial genes during VPA-treatment, increasing complexities of gene-interaction networks across time were demonstrated, which normalized during washout. Furthermore, co-expression between genes and their corresponding proteins increased across time. Additionally, in relation to persistently decreased ATP production, we observed decreased expression of mitochondrial complex I and III-V genes. Persistent transcripts and proteins were related to citric acid cycle and β-oxidation. In particular, we identified a potential novel mitochondrial-nuclear signaling axis, MT-CO2-FN1-MYC-CPT1. In summary, this cross-omics study revealed dynamic responses of the mitochondrial epigenome to an impulse toxicant challenge resulting in persistent mitochondrial dysfunctioning. Moreover, this approach allowed for discriminating between the toxic effect of VPA and adaptation. Copyright © 2018 Elsevier B.V. All rights reserved.

Regional differences in mitochondrial DNA methylation in human post-mortem brain tissue.

PubMed

Devall, Matthew; Smith, Rebecca G; Jeffries, Aaron; Hannon, Eilis; Davies, Matthew N; Schalkwyk, Leonard; Mill, Jonathan; Weedon, Michael; Lunnon, Katie

2017-01-01

DNA methylation is an important epigenetic mechanism involved in gene regulation, with alterations in DNA methylation in the nuclear genome being linked to numerous complex diseases. Mitochondrial DNA methylation is a phenomenon that is receiving ever-increasing interest, particularly in diseases characterized by mitochondrial dysfunction; however, most studies have been limited to the investigation of specific target regions. Analyses spanning the entire mitochondrial genome have been limited, potentially due to the amount of input DNA required. Further, mitochondrial genetic studies have been previously confounded by nuclear-mitochondrial pseudogenes. Methylated DNA Immunoprecipitation Sequencing is a technique widely used to profile DNA methylation across the nuclear genome; however, reads mapped to mitochondrial DNA are often discarded. Here, we have developed an approach to control for nuclear-mitochondrial pseudogenes within Methylated DNA Immunoprecipitation Sequencing data. We highlight the utility of this approach in identifying differences in mitochondrial DNA methylation across regions of the human brain and pre-mortem blood. We were able to correlate mitochondrial DNA methylation patterns between the cortex, cerebellum and blood. We identified 74 nominally significant differentially methylated regions ( p  < 0.05) in the mitochondrial genome, between anatomically separate cortical regions and the cerebellum in matched samples ( N  = 3 matched donors). Further analysis identified eight significant differentially methylated regions between the total cortex and cerebellum after correcting for multiple testing. Using unsupervised hierarchical clustering analysis of the mitochondrial DNA methylome, we were able to identify tissue-specific patterns of mitochondrial DNA methylation between blood, cerebellum and cortex. Our study represents a comprehensive analysis of the mitochondrial methylome using pre-existing Methylated DNA Immunoprecipitation

Interchangeable adaptors regulate mitochondrial dynamin assembly for membrane scission

PubMed Central

Koirala, Sajjan; Guo, Qian; Kalia, Raghav; Bui, Huyen T.; Eckert, Debra M.; Frost, Adam; Shaw, Janet M.

2013-01-01

Mitochondrial fission is mediated by the dynamin-related GTPases Dnm1/Drp1 (yeast/mammals), which form spirals around constricted sites on mitochondria. Additional membrane-associated adaptor proteins (Fis1, Mdv1, Mff, and MiDs) are required to recruit these GTPases from the cytoplasm to the mitochondrial surface. Whether these adaptors participate in both GTPase recruitment and membrane scission is not known. Here we use a yeast strain lacking all fission proteins to identify the minimal combinations of GTPases and adaptors sufficient for mitochondrial fission. Although Fis1 is dispensable for fission, membrane-anchored Mdv1, Mff, or MiDs paired individually with their respective GTPases are sufficient to divide mitochondria. In addition to their role in Drp1 membrane recruitment, MiDs coassemble with Drp1 in vitro. The resulting heteropolymer adopts a dramatically different structure with a narrower diameter than Drp1 homopolymers assembled in isolation. This result demonstrates that an adaptor protein alters the architecture of a mitochondrial dynamin GTPase polymer in a manner that could facilitate membrane constriction and severing activity. PMID:23530241

SR/ER-mitochondrial local communication: Calcium and ROS

PubMed Central

Csordás, György; Hajnóczky, György

2009-01-01

Mitochondria form junctions with the sarco/endoplasmic reticulum (SR/ER), which support signal transduction and biosynthetic pathways and affect organellar distribution. Recently, these junctions have received attention because of their pivotal role in mediating calcium signal propagation to the mitochondria, which is important for both ATP production and mitochondrial cell death. Many of the SR/ER-mitochondrial calcium transporters and signaling proteins are sensitive to redox regulation and are directly exposed to the reactive oxygen species (ROS) produced in the mitochondria and SR/ER. Although ROS has been emerging as a novel signaling entity, the redox signaling of the SR/ER-mitochondrial interface is yet to be elucidated. We describe here possible mechanisms of the mutual interaction between local Ca2+ and ROS signaling in the control of SR/ER-mitochondrial function. PMID:19527680

Resveratrol Rescues Kidney Mitochondrial Function Following Hemorrhagic Shock

PubMed Central

Wang, Hao; Guan, Yuxia; Karamercan, Mehmet Akif; Ye, Lan; Bhatti, Tricia; Becker, Lance B.; Baur, Joseph A.; Sims, Carrie A.

2015-01-01

Objective Hemorrhagic shock may contribute to acute kidney injury by profoundly altering renal mitochondrial function. Resveratrol (RSV), a naturally occurring sirtuin-1 (SIRT1) activator, has been shown to promote mitochondrial function and reduce oxidative damage in a variety of aging-related disease states. We hypothesized that RSV treatment during resuscitation would ameliorate kidney mitochondrial dysfunction and decrease oxidative damage following hemorrhagic shock. Method Using a decompensated hemorrhagic shock model, male Long-Evans rats (n=6 per group) were sacrificed prior to hemorrhage (Sham), at severe shock, and following either lactated Ringer’s (LR) Resuscitation or LR+RSV Resuscitation (RSV: 30mg/kg). At each time point, blood samples were assayed for arterial blood gases, lactate, blood urea nitrogen (BUN) and serum creatinine. Mitochondria were also isolated from kidney samples in order to assess individual electron transport complexes (CI, CII, and CIV) using high-resolution respirometry. Total mitochondria reactive oxygen species (ROS) were measured using fluorometry and lipid peroxidation was assessed by measuring 4-hydroxynonenal by Western blot. qPCR was used quantify mRNA from PGC1-α, SIRT1, and proteins known to mitigate oxidative damage and promote mitochondrial biogenesis. Results RSV supplementation during resuscitation restored mitochondrial respiratory capacity, decreased mitochondrial ROS and lipid peroxidation. Compared to standard LR resuscitation, RSV treatment significantly increased SIRT1 and PGC1-α expression and significantly increased both SOD2 and catalase expression. Although RSV was associated with decreased lactate production, pH, BUN and serum creatinine values did not differ between resuscitation strategies. Conclusions Resuscitation with RSV significantly restored renal mitochondrial function and decreased oxidative damage following hemorrhagic shock. PMID:25895148

Metabolic Plasticity in Cancer Cells: Reconnecting Mitochondrial Function to Cancer Control

PubMed Central

Ramanujan, V. Krishnan

2015-01-01

Anomalous increase in glycolytic activity defines one of the key metabolic alterations in cancer cells. A realization of this feature has led to critical advancements in cancer detection techniques such as positron emission tomography (PET) as well as a number of therapeutic avenues targeting the key glycolytic steps within a cancer cell. A normal healthy cell’s survival relies on a sensitive balance between the primordial glycolysis and a more regulated mitochondrial bioenergetics. The salient difference between these two bioenergetics pathways is that oxygen availability is an obligatory requirement for mitochondrial pathway while glycolysis can function without oxygen. Early observations that some cancer cells up-regulate glycolytic activity even in the presence of oxygen (aerobic glycolysis) led to a hypothesis that such an altered cancer cell metabolism stems from inherent mitochondrial dysfunction. While a general validity of this hypothesis is still being debated, a number of recent research efforts have yielded clarity on the physiological origins of this aerobic glycolysis phenotype in cancer cells. Building on these recent studies, we present a generalized scheme of cancer cell metabolism and propose a novel hypothesis that might rationalize new avenues of cancer intervention. PMID:26457230

Mitochondrial functions modulate neuroendocrine, metabolic, inflammatory, and transcriptional responses to acute psychological stress

PubMed Central

Picard, Martin; McManus, Meagan J.; Gray, Jason D.; Nasca, Carla; Moffat, Cynthia; Kopinski, Piotr K.; Seifert, Erin L.; McEwen, Bruce S.; Wallace, Douglas C.

2015-01-01

The experience of psychological stress triggers neuroendocrine, inflammatory, metabolic, and transcriptional perturbations that ultimately predispose to disease. However, the subcellular determinants of this integrated, multisystemic stress response have not been defined. Central to stress adaptation is cellular energetics, involving mitochondrial energy production and oxidative stress. We therefore hypothesized that abnormal mitochondrial functions would differentially modulate the organism’s multisystemic response to psychological stress. By mutating or deleting mitochondrial genes encoded in the mtDNA [NADH dehydrogenase 6 (ND6) and cytochrome c oxidase subunit I (COI)] or nuclear DNA [adenine nucleotide translocator 1 (ANT1) and nicotinamide nucleotide transhydrogenase (NNT)], we selectively impaired mitochondrial respiratory chain function, energy exchange, and mitochondrial redox balance in mice. The resulting impact on physiological reactivity and recovery from restraint stress were then characterized. We show that mitochondrial dysfunctions altered the hypothalamic–pituitary–adrenal axis, sympathetic adrenal–medullary activation and catecholamine levels, the inflammatory cytokine IL-6, circulating metabolites, and hippocampal gene expression responses to stress. Each mitochondrial defect generated a distinct whole-body stress-response signature. These results demonstrate the role of mitochondrial energetics and redox balance as modulators of key pathophysiological perturbations previously linked to disease. This work establishes mitochondria as stress-response modulators, with implications for understanding the mechanisms of stress pathophysiology and mitochondrial diseases. PMID:26627253

Insulin upregulates GRIM-19 and protects cardiac mitochondrial morphology in type 1 diabetic rats partly through PI3K/AKT signaling pathway.

PubMed

Li, Yong-Guang; Dong, Zhi-Feng; Chen, Kan-Kai; He, Ya-Ping; Dai, Xiao-Yan; Li, Shuai; Li, Jing-Bo; Zhu, Wei; Wei, Meng

2017-11-04

Insulin is involved in the development of diabetic heart disease and is important in the activities of mitochondrial complex I. However, the effect of insulin on cardiac mitochondrial nicotinamide adenine dinucleotide dehydrogenase (ubiquinone) 1 subunit of retinoic-interferon-induced mortality 19 (GRIM-19) has not been characterized. The aim of this study was to investigate the effect of insulin on the mitochondrial GRIM-19 in the hearts of rats with streptozotocin (STZ)-induced type 1 diabetes. Protein changes of GRIM-19 were evaluated by western blotting and reverse transcription-quantitative polymerase chain reaction. Furthermore, the effects of insulin on mitochondrial complex I were detected in HeLa cells and H9C2 cardiac myocytes. During the development of diabetic heart disease, the cardiac function did not change within the 8 weeks, but the mitochondrial morphology was altered. The hearts from the rats with STZ-induced diabetes exhibited reduced expression of GRIM-19. Prior to the overt cardiac dilatation, mitochondrial alterations were already present. Following subcutaneous insulin injection, it was demonstrated that GRIM-19 protein was altered, as well as the mitochondrial morphology. The phosphoinositide 3-kinase inhibitor LY294002 had an effect on insulin signaling in H9C2 cardiacmyocytes, and decreased the level of GRIM-19 by half compared with that in the insulin group. The results indicate that insulin is essential for the control of cardiac mitochondrial morphology and the GRIM-19 expression partly via PI3K/AKT signaling pathways. Copyright © 2017. Published by Elsevier Inc.

Aging-dependent alterations in gene expression and a mitochondrial signature of responsiveness to human influenza vaccination.

PubMed

Thakar, Juilee; Mohanty, Subhasis; West, A Phillip; Joshi, Samit R; Ueda, Ikuyo; Wilson, Jean; Meng, Hailong; Blevins, Tamara P; Tsang, Sui; Trentalange, Mark; Siconolfi, Barbara; Park, Koonam; Gill, Thomas M; Belshe, Robert B; Kaech, Susan M; Shadel, Gerald S; Kleinstein, Steven H; Shaw, Albert C

2015-01-01

To elucidate gene expression pathways underlying age-associated impairment in influenza vaccine response, we screened young (age 21-30) and older (age≥65) adults receiving influenza vaccine in two consecutive seasons and identified those with strong or absent response to vaccine, including a subset of older adults meeting criteria for frailty. PBMCs obtained prior to vaccination (Day 0) and at day 2 or 4, day 7 and day 28 post-vaccine were subjected to gene expression microarray analysis. We defined a response signature and also detected induction of a type I interferon response at day 2 and a plasma cell signature at day 7 post-vaccine in young responders. The response signature was dysregulated in older adults, with the plasma cell signature induced at day 2, and was never induced in frail subjects (who were all non-responders). We also identified a mitochondrial signature in young vaccine responders containing genes mediating mitochondrial biogenesis and oxidative phosphorylation that was consistent in two different vaccine seasons and verified by analyses of mitochondrial content and protein expression. These results represent the first genome-wide transcriptional profiling analysis of age-associated dynamics following influenza vaccination, and implicate changes in mitochondrial biogenesis and function as a critical factor in human vaccine responsiveness.

Human Cytochrome P450 2E1 Mutations That Alter Mitochondrial Targeting Efficiency and Susceptibility to Ethanol-induced Toxicity in Cellular Models*

PubMed Central

Bansal, Seema; Anandatheerthavarada, Hindupur K.; Prabu, Govindaswamy K.; Milne, Ginger L.; Martin, Martha V.; Guengerich, F. Peter; Avadhani, Narayan G.

2013-01-01

Human polymorphisms in the 5′-upstream regulatory regions and also protein coding regions of cytochrome P450 2E1 (CYP2E1) are known to be associated with several diseases, including cancer and alcohol liver toxicity. In this study, we report novel mutations in the N-terminal protein targeting regions of CYP2E1 that markedly affect subcellular localization of the protein. Variant W23R/W30R protein (termed W23/30R) is preferentially targeted to mitochondria but very poorly to the endoplasmic reticulum, whereas the L32N protein is preferentially targeted to the endoplasmic reticulum and poorly to mitochondria. These results explain the physiological significance of bimodal CYP targeting to the endoplasmic reticulum and mitochondria previously described. COS-7 cells and HepG2 cells stably expressing W23/30R mutations showed markedly increased alcohol toxicity in terms of increased production of reactive oxygen species, respiratory dysfunction, and loss of cytochrome c oxidase subunits and activity. Stable cells expressing the L32N variant, on the other hand, were relatively less responsive to alcohol-induced toxicity and mitochondrial dysfunction. These results further support our previous data, based on mutational studies involving altered targeting, indicating that mitochondria-targeted CYP2E1 plays an important role in alcohol liver toxicity. The results also provide an interesting new link to genetic variations affecting subcellular distribution of CYP2E1 with alcohol-induced toxicity. PMID:23471973

Mitochondrial-related gene expression changes are sensitive to agonal-pH state: implications for brain disorders

PubMed Central

Vawter, MP; Tomita, H; Meng, F; Bolstad, B; Li, J; Evans, S; Choudary, P; Atz, M; Shao, L; Neal, C; Walsh, DM; Burmeister, M; Speed, T; Myers, R; Jones, EG; Watson, SJ; Akil, H; Bunney, WE

2010-01-01

Mitochondrial defects in gene expression have been implicated in the pathophysiology of bipolar disorder and schizophrenia. We have now contrasted control brains with low pH versus high pH and showed that 28% of genes in mitochondrial-related pathways meet criteria for differential expression. A majority of genes in the mitochondrial, chaperone and proteasome pathways of nuclear DNA-encoded gene expression were decreased with decreased brain pH, whereas a majority of genes in the apoptotic and reactive oxygen stress pathways showed an increased gene expression with a decreased brain pH. There was a significant increase in mitochondrial DNA copy number and mitochondrial DNA gene expression with increased agonal duration. To minimize effects of agonal-pH state on mood disorder comparisons, two classic approaches were used, removing all subjects with low pH and agonal factors from analysis, or grouping low and high pH as a separate variable. Three groups of potential candidate genes emerged that may be mood disorder related: (a) genes that showed no sensitivity to pH but were differentially expressed in bipolar disorder or major depressive disorder; (b) genes that were altered by agonal-pH in one direction but altered in mood disorder in the opposite direction to agonal-pH and (c) genes with agonal-pH sensitivity that displayed the same direction of changes in mood disorder. Genes from these categories such as NR4A1 and HSPA2 were confirmed with Q-PCR. The interpretation of postmortem brain studies involving broad mitochondrial gene expression and related pathway alterations must be monitored against the strong effect of agonal-pH state. Genes with the least sensitivity to agonal-pH could present a starting point for candidate gene search in neuropsychiatric disorders. PMID:16636682

A Mitochondrial Story: Mitochondrial Replacement, Identity and Narrative.

PubMed

Scully, Jackie Leach

2017-01-01

Mitochondrial replacement techniques (MRT) are intended to avoid the transmission of mitochondrial diseases from mother to child. MRT represent a potentially powerful new biomedical technology with ethical, policy, economic and social implications. Among other ethical questions raised are concerns about the possible effects on the identity of children born from MRT, their families, and the providers or donors of mitochondria. It has been suggested that MRT can influence identity (i) directly, through altering the genetic makeup and physical characteristics of the child, or (ii) indirectly through changing the child's experience of disease, and by generating novel intrafamilial relationships that shape the sense of self. In this article I consider the plausibility and ethical implications of these proposed identity effects, but I focus instead on a third way in which identity may be affected, through the mediating influence of the wider social world on MRT effects on identity. By taking a narrative approach, and examining the nature and availability of identity narratives, I conclude that while neither direct genetic nor indirect experiential effects can be excluded, social responses to MRT are more likely to have a significant and potentially damaging influence on the generation of MRT children's narratives of identity. This conclusion carries some implications for the collective moral responsibility we hold to ensure that MRT, if implemented, are practised in ethically justifiable ways. © 2017 John Wiley & Sons Ltd.

Mitochondrial vasculopathy

PubMed Central

Finsterer, Josef; Zarrouk-Mahjoub, Sinda

2016-01-01

Mitochondrial disorders (MIDs) are usually multisystem disorders (mitochondrial multiorgan disorder syndrome) either on from onset or starting at a point during the disease course. Most frequently affected tissues are those with a high oxygen demand such as the central nervous system, the muscle, endocrine glands, or the myocardium. Recently, it has been shown that rarely also the arteries may be affected (mitochondrial arteriopathy). This review focuses on the type, diagnosis, and treatment of mitochondrial vasculopathy in MID patients. A literature search using appropriate search terms was carried out. Mitochondrial vasculopathy manifests as either microangiopathy or macroangiopathy. Clinical manifestations of mitochondrial microangiopathy include leukoencephalopathy, migraine-like headache, stroke-like episodes, or peripheral retinopathy. Mitochondrial macroangiopathy manifests as atherosclerosis, ectasia of arteries, aneurysm formation, dissection, or spontaneous rupture of arteries. The diagnosis relies on the documentation and confirmation of the mitochondrial metabolic defect or the genetic cause after exclusion of non-MID causes. Treatment is not at variance compared to treatment of vasculopathy due to non-MID causes. Mitochondrial vasculopathy exists and manifests as micro- or macroangiopathy. Diagnosing mitochondrial vasculopathy is crucial since appropriate treatment may prevent from severe complications. PMID:27231520

Exosomes derived from B16F0 melanoma cells alter the transcriptome of cytotoxic T cells that impacts mitochondrial respiration.

PubMed

Bland, Cassidy L; Byrne-Hoffman, Christina N; Fernandez, Audry; Rellick, Stephanie L; Deng, Wentao; Klinke, David J

2018-03-01

While recent clinical studies demonstrate the promise of cancer immunotherapy, a barrier for broadening the clinical benefit is identifying how tumors locally suppress cytotoxic immunity. As an emerging mode of intercellular communication, exosomes secreted by malignant cells can deliver a complex payload of coding and noncoding RNA to cells within the tumor microenvironment. Here, we quantified the RNA payload within tumor-derived exosomes and the resulting dynamic transcriptomic response to cytotoxic T cells upon exosome delivery to better understand how tumor-derived exosomes can alter immune cell function. Exosomes derived from B16F0 melanoma cells were enriched for a subset of coding and noncoding RNAs that did not reflect the abundance in the parental cell. Upon exosome delivery, RNAseq revealed the dynamic changes in the transcriptome of CTLL2 cytotoxic T cells. In analyzing transiently coexpressed gene clusters, pathway enrichment suggested that the B16F0 exosomal payload altered mitochondrial respiration, which was confirmed independently, and upregulated genes associated with the Notch signaling pathway. Interestingly, exosomal miRNA appeared to have no systematic effect on downregulating target mRNA levels. Gene expression data are available in the GEO database under the accession SuperSeries number GSE102951. © 2018 Federation of European Biochemical Societies.

Mitochondrial deficits and abnormal mitochondrial retrograde axonal transport play a role in the pathogenesis of mutant Hsp27-induced Charcot Marie Tooth Disease.

PubMed

Kalmar, Bernadett; Innes, Amy; Wanisch, Klaus; Kolaszynska, Alicia Koyen; Pandraud, Amelie; Kelly, Gavin; Abramov, Andrey Y; Reilly, Mary M; Schiavo, Giampietro; Greensmith, Linda

2017-09-01

Mutations in the small heat shock protein Hsp27, encoded by the HSPB1 gene, have been shown to cause Charcot Marie Tooth Disease type 2 (CMT-2) or distal hereditary motor neuropathy (dHMN). Protein aggregation and axonal transport deficits have been implicated in the disease. In this study, we conducted analysis of bidirectional movements of mitochondria in primary motor neuron axons expressing wild type and mutant Hsp27. We found significantly slower retrograde transport of mitochondria in Ser135Phe, Pro39Leu and Arg140Gly mutant Hsp27 expressing motor neurons than in wild type Hsp27 neurons, although anterograde movement velocities remained normal. Retrograde transport of other important cargoes, such as the p75 neurotrophic factor receptor was minimally altered in mutant Hsp27 neurons, implicating that axonal transport deficits primarily affect mitochondria and the axonal transport machinery itself is less affected. Investigation of mitochondrial function revealed a decrease in mitochondrial membrane potential in mutant Hsp27 expressing motor axons, as well as a reduction in mitochondrial complex 1 activity, increased vulnerability of mitochondria to mitochondrial stressors, leading to elevated superoxide release and reduced mitochondrial glutathione (GSH) levels, although cytosolic GSH remained normal. This mitochondrial redox imbalance in mutant Hsp27 motor neurons is likely to cause low level of oxidative stress, which in turn will contribute to, and indeed may be the underlying cause of the deficits in mitochondrial axonal transport. Together, these findings suggest that the mitochondrial abnormalities in mutant Hsp27-induced neuropathies may be a primary cause of pathology, leading to further deficits in the mitochondrial axonal transport and onset of disease. © The Author 2017. Published by Oxford University Press.

Nitrate-containing beetroot enhances myocyte metabolism and mitochondrial content

PubMed Central

Vaughan, Roger A.; Gannon, Nicholas P.; Carriker, Colin R.

2015-01-01

Beetroot (甜菜 tián cài) juice consumption is of current interest for improving aerobic performance by acting as a vasodilator and possibly through alterations in skeletal muscle metabolism and physiology. This work explored the effects of a commercially available beetroot supplement on metabolism, gene expression, and mitochondrial content in cultured myocytes. C2C12 myocytes were treated with various concentrations of the beetroot supplement for various durations. Glycolytic metabolism and oxidative metabolism were quantified via measurement of extracellular acidification and oxygen consumption, respectively. Metabolic gene expression was measured using quantitative reverse transcription–polymerase chain reaction, and mitochondrial content was assessed with flow cytometry and confocal microscopy. Cells treated with beetroot exhibited significantly increased oxidative metabolism, concurrently with elevated metabolic gene expression including peroxisome proliferator-activated receptor gamma coactivator-1 alpha, nuclear respiratory factor 1, mitochondrial transcription factor A, and glucose transporter 4, leading to increased mitochondrial biogenesis. Our data show that treatment with a beetroot supplement increases basal oxidative metabolism. Our observations are also among the first to demonstrate that beetroot extract is an inducer of metabolic gene expression and mitochondrial biogenesis. These observations support the need for further investigation into the therapeutic and pharmacological effects of nitrate-containing supplements for health and athletic benefits. PMID:26870674

Correlation of mitochondrial protein expression in complexes I to V with natural and induced forms of canine idiopathic dilated cardiomyopathy.

PubMed

Lopes, Rosana; Solter, Philip F; Sisson, D David; Oyama, Mark A; Prosek, Robert

2006-06-01

To identify qualitative and quantitative differences in cardiac mitochondrial protein expression in complexes I to V between healthy dogs and dogs with natural or induced dilated cardiomyopathy (DCM). Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with DCM induced by rapid right ventricular pacing. Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by 2-fold or greater between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. A total of 22 altered mitochondrial proteins were identified in complexes I to V. Ten and 12 were found in complex I and complexes II to V, respectively. Five were mitochondrial encoded, and 17 were nuclear encoded. Most altered mitochondrial proteins in tissue specimens from dogs with naturally occurring DCM were associated with complexes I and V, whereas in tissue specimens from dogs subjected to rapid ventricular pacing, complexes I and IV were more affected. In the experimentally induced form of DCM, only nuclear-encoded subunits were changed in complex I. In both disease groups, the 22-kd subunit was downregulated. Natural and induced forms of DCM resulted in altered mitochondrial protein expression in complexes I to V. However, subcellular differences between the experimental and naturally occurring forms of DCM may exist.

High-resolution respirometry of fine-needle muscle biopsies in pre-manifest Huntington's disease expansion mutation carriers shows normal mitochondrial respiratory function.

PubMed

Buck, Eva; Zügel, Martina; Schumann, Uwe; Merz, Tamara; Gumpp, Anja M; Witting, Anke; Steinacker, Jürgen M; Landwehrmeyer, G Bernhard; Weydt, Patrick; Calzia, Enrico; Lindenberg, Katrin S

2017-01-01

Alterations in mitochondrial respiration are an important hallmark of Huntington's disease (HD), one of the most common monogenetic causes of neurodegeneration. The ubiquitous expression of the disease causing mutant huntingtin gene raises the prospect that mitochondrial respiratory deficits can be detected in skeletal muscle. While this tissue is readily accessible in humans, transgenic animal models offer the opportunity to cross-validate findings and allow for comparisons across organs, including the brain. The integrated respiratory chain function of the human vastus lateralis muscle was measured by high-resolution respirometry (HRR) in freshly taken fine-needle biopsies from seven pre-manifest HD expansion mutation carriers and nine controls. The respiratory parameters were unaffected. For comparison skeletal muscle isolated from HD knock-in mice (HdhQ111) as well as a broader spectrum of tissues including cortex, liver and heart muscle were examined by HRR. Significant changes of mitochondrial respiration in the HdhQ knock-in mouse model were restricted to the liver and the cortex. Mitochondrial mass as quantified by mitochondrial DNA copy number and citrate synthase activity was stable in murine HD-model tissue compared to control. mRNA levels of key enzymes were determined to characterize mitochondrial metabolic pathways in HdhQ mice. We demonstrated the feasibility to perform high-resolution respirometry measurements from small human HD muscle biopsies. Furthermore, we conclude that alterations in respiratory parameters of pre-manifest human muscle biopsies are rather limited and mirrored by a similar absence of marked alterations in HdhQ skeletal muscle. In contrast, the HdhQ111 murine cortex and liver did show respiratory alterations highlighting the tissue specific nature of mutant huntingtin effects on respiration.

The human T-cell leukemia virus type 1 p13II protein: effects on mitochondrial function and cell growth

PubMed Central

D’Agostino, DM; Silic-Benussi, M; Hiraragi, H; Lairmore, MD; Ciminale, V

2011-01-01

p13II of human T-cell leukemia virus type 1 (HTLV-1) is an 87-amino-acid protein that is targeted to the inner mitochondrial membrane. p13II alters mitochondrial membrane permeability, producing a rapid, membrane potential-dependent influx of K+. These changes result in increased mitochondrial matrix volume and fragmentation and may lead to depolarization and alterations in mitochondrial Ca2+ uptake/retention capacity. At the cellular level, p13II has been found to interfere with cell proliferation and transformation and to promote apoptosis induced by ceramide and Fas ligand. Assays carried out in T cells (the major targets of HTLV-1 infection in vivo) demonstrate that p13II-mediated sensitization to Fas ligand-induced apoptosis can be blocked by an inhibitor of Ras farnesylation, thus implicating Ras signaling as a downstream target of p13II function. PMID:15761473

Impaired Muscle Mitochondrial Biogenesis and Myogenesis in Spinal Muscular Atrophy

PubMed Central

Ripolone, Michela; Ronchi, Dario; Violano, Raffaella; Vallejo, Dionis; Fagiolari, Gigliola; Barca, Emanuele; Lucchini, Valeria; Colombo, Irene; Villa, Luisa; Berardinelli, Angela; Balottin, Umberto; Morandi, Lucia; Mora, Marina; Bordoni, Andreina; Fortunato, Francesco; Corti, Stefania; Parisi, Daniela; Toscano, Antonio; Sciacco, Monica; DiMauro, Salvatore; Comi, Giacomo P.; Moggio, Maurizio

2016-01-01

IMPORTANCE The important depletion of mitochondrial DNA (mtDNA) and the general depression of mitochondrial respiratory chain complex levels (including complex II) have been confirmed, implying an increasing paucity of mitochondria in the muscle from patients with types I, II, and III spinal muscular atrophy (SMA-I, -II, and -III, respectively). OBJECTIVE To investigate mitochondrial dysfunction in a large series of muscle biopsy samples from patients with SMA. DESIGN, SETTING, AND PARTICIPANTS We studied quadriceps muscle samples from 24 patients with genetically documented SMA and paraspinal muscle samples from 3 patients with SMA-II undergoing surgery for scoliosis correction. Postmortem muscle samples were obtained from 1 additional patient. Age-matched controls consisted of muscle biopsy specimens from healthy children aged 1 to 3 years who had undergone analysis for suspected myopathy. Analyses were performed at the Neuromuscular Unit, Istituto di Ricovero e Cura a Carattere Scientifico Foundation Ca’ Granda Ospedale Maggiore Policlinico-Milano, from April 2011 through January 2015. EXPOSURES We used histochemical, biochemical, and molecular techniques to examine the muscle samples. MAIN OUTCOMES AND MEASURES Respiratory chain activity and mitochondrial content. RESULTS Results of histochemical analysis revealed that cytochrome-c oxidase (COX) deficiency was more evident in muscle samples from patients with SMA-I and SMA-II. Residual activities for complexes I, II, and IV in muscles from patients with SMA-I were 41%, 27%, and 30%, respectively, compared with control samples (P < .005). Muscle mtDNA content and cytrate synthase activity were also reduced in all 3 SMA types (P < .05). We linked these alterations to downregulation of peroxisome proliferator–activated receptor coactivator 1α, the transcriptional activators nuclear respiratory factor 1 and nuclear respiratory factor 2, mitochondrial transcription factor A, and their downstream targets

Cholecystokinin induces caspase activation and mitochondrial dysfunction in pancreatic acinar cells. Roles in cell injury processes of pancreatitis.

PubMed

Gukovskaya, Anna S; Gukovsky, Ilya; Jung, Yoon; Mouria, Michelle; Pandol, Stephen J

2002-06-21

Apoptosis and necrosis are critical parameters of pancreatitis, the mechanisms of which remain unknown. Many characteristics of pancreatitis can be studied in vitro in pancreatic acini treated with high doses of cholecystokinin (CCK). We show here that CCK stimulates apoptosis and death signaling pathways in rat pancreatic acinar cells, including caspase activation, cytochrome c release, and mitochondrial depolarization. The mitochondrial dysfunction is mediated by upstream caspases (possibly caspase-8) and, in turn, leads to activation of caspase-3. CCK causes mitochondrial alterations through both permeability transition pore-dependent (cytochrome c release) and permeability transition pore-independent (mitochondrial depolarization) mechanisms. Caspase activation and mitochondrial alterations also occur in untreated pancreatic acinar cells; however, the underlying mechanisms are different. In particular, caspases protect untreated acinar cells from mitochondrial damage. We found that caspases not only mediate apoptosis but also regulate other parameters of CCK-induced acinar cell injury that are characteristic of pancreatitis; in particular, caspases negatively regulate necrosis and trypsin activation in acinar cells. The results suggest that the observed signaling pathways regulate parenchymal cell injury and death in CCK-induced pancreatitis. Protection against necrosis and trypsin activation by caspases can explain why the severity of pancreatitis in experimental models correlates inversely with the extent of apoptosis.

Mitochondrial respiratory chain Complex I defects in Fanconi anemia complementation group A.

PubMed

Ravera, Silvia; Vaccaro, Daniele; Cuccarolo, Paola; Columbaro, Marta; Capanni, Cristina; Bartolucci, Martina; Panfoli, Isabella; Morelli, Alessandro; Dufour, Carlo; Cappelli, Enrico; Degan, Paolo

2013-10-01

Fanconi anemia (FA) is a rare and complex inherited blood disorder of the child. At least 15 genes are associated with the disease. The highest frequency of mutations belongs to groups A, C and G. Genetic instability and cytokine hypersensitivity support the selection of leukemic over non-leukemic stem cells. FA cellular phenotype is characterized by alterations in red-ox state, mitochondrial functionality and energy metabolism as reported in the past however a clear picture of the altered biochemical phenotype in FA is still elusive and the final biochemical defect(s) still unknown. Here we report an analysis of the respiratory fluxes in FANCA primary fibroblasts, lymphocytes and lymphoblasts. FANCA mutants show defective respiration through Complex I, diminished ATP production and metabolic sufferance with an increased AMP/ATP ratio. Respiration in FANCC mutants is normal. Treatment with N-acetyl-cysteine (NAC) restores oxygen consumption to normal level. Defective respiration in FANCA mutants appear correlated with the FA pro-oxidative phenotype which is consistent with the altered morphology of FANCA mitochondria. Electron microscopy measures indeed show profound alterations in mitochondrial ultrastructure and shape. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Mitochondrial genomes of parasitic flatworms.

PubMed

Le, Thanh H; Blair, David; McManus, Donald P

2002-05-01

Complete or near-complete mitochondrial genomes are now available for 11 species or strains of parasitic flatworms belonging to the Trematoda and the Cestoda. The organization of these genomes is not strikingly different from those of other eumetazoans, although one gene (atp8) commonly found in other phyla is absent from flatworms. The gene order in most flatworms has similarities to those seen in higher protostomes such as annelids. However, the gene order has been drastically altered in Schistosoma mansoni, which obscures this possible relationship. Among the sequenced taxa, base composition varies considerably, creating potential difficulties for phylogeny reconstruction. Long non-coding regions are present in all taxa, but these vary in length from only a few hundred to approximately 10000 nucleotides. Among Schistosoma spp., the long non-coding regions are rich in repeats and length variation among individuals is known. Data from mitochondrial genomes are valuable for studies on species identification, phylogenies and biogeography.

Manganese induces mitochondrial dynamics impairment and apoptotic cell death: a study in human Gli36 cells.

PubMed

Alaimo, Agustina; Gorojod, Roxana M; Miglietta, Esteban A; Villarreal, Alejandro; Ramos, Alberto J; Kotler, Mónica L

2013-10-25

Manganese (Mn) is an essential trace element due to its participation in many physiological processes. However, overexposure to this metal leads to a neurological disorder known as Manganism whose clinical manifestations and molecular mechanisms resemble Parkinson's disease. Several lines of evidence implicate astrocytes as an early target of Mn neurotoxicity being the mitochondria the most affected organelles. The aim of this study was to investigate the possible mitochondrial dynamics alterations in Mn-exposed human astrocytes. Therefore, we employed Gli36 cells which express the astrocytic markers GFAP and S100B. We demonstrated that Mn triggers the mitochondrial apoptotic pathway revealed by increased Bax/Bcl-2 ratio, by the loss of mitochondrial membrane potential and by caspase-9 activation. This apoptotic program may be in turn responsible of caspase-3/7 activation, PARP-1 cleavage, chromatin condensation and fragmentation. In addition, we determined that Mn induces deregulation in mitochondria-shaping proteins (Opa-1, Mfn-2 and Drp-1) expression levels in parallel with the disruption of the mitochondrial network toward to an exacerbated fragmentation. Since mitochondrial dynamics is altered in several neurodegenerative diseases, these proteins could become future targets to be considered in Manganism treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Animal inference on human mitochondrial diseases.

PubMed

Nardi, Francesco; Frati, Francesco; Liò, Pietro

2016-06-01

Several pathological mutations in the human mitochondrial genome have been characterized based on medical, genetic and biochemical evidence. The observation that the structure and core functions of the mitochondrial genome are conserved from animals to man suggests that the analysis of animal variation may be informative to further characterize, and possibly predict, human pathological variants. We studied the distribution of sequence site-wise diversity and structural heterogeneity (based on several scales of hydrophobicity and supercomplex classification of mitochondrial genes) at different taxonomic levels in ∼15,000 human and animal genomes. We found that human pathological mutations tend to lay in regions of low diversity and that states that are pathological in humans appear to be extremely rare in animals, with two noticeable exceptions (T10663C and C14568T). Focusing on hydrophobicity, as possibly the most general site-wise functional parameter of a protein, we deploy the observed range of hydrophobicity in mammals as a proxy for the range of permissible states compatible with an efficient functioning of the mitochondrial machinery. We show that, while non pathological human variants tend to fall within the hypothesized range, pathological mutations generally fall outside this range. We further analyzed this distribution quantitatively to show that the estimated probability of observed states can indeed be used to predict the pathogenicity of a mutation in humans. This study provides a proof of principle that animal data can indeed be informative to predict the pathogenicity of a human mutation alongside, or in the absence of, additional evidence. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

High-fat diet induces an initial adaptation of mitochondrial bioenergetics in the kidney despite evident oxidative stress and mitochondrial ROS production

PubMed Central

Ruggiero, Christine; Ehrenshaft, Marilyn; Cleland, Ellen

2011-01-01

Obesity and metabolic syndrome are associated with an increased risk for several diabetic complications, including diabetic nephropathy and chronic kidney diseases. Oxidative stress and mitochondrial dysfunction are often proposed mechanisms in various organs in obesity models, but limited data are available on the kidney. Here, we fed a lard-based high-fat diet to mice to investigate structural changes, cellular and subcellular oxidative stress and redox status, and mitochondrial biogenesis and function in the kidney. The diet induced characteristic changes, including glomerular hypertrophy, fibrosis, and interstitial scarring, which were accompanied by a proinflammatory transition. We demonstrate evidence for oxidative stress in the kidney through 3-nitrotyrosine and protein radical formation on high-fat diet with a contribution from iNOS and NOX-4 as well as increased generation of mitochondrial oxidants on carbohydrate- and lipid-based substrates. The increased H2O2 emission in the mitochondria suggests altered redox balance and mitochondrial ROS generation, contributing to the overall oxidative stress. No major derailments were observed in respiratory function or biogenesis, indicating preserved and initially improved bioenergetic parameters and energy production. We suggest that, regardless of the oxidative stress events, the kidney developed an adaptation to maintain normal respiratory function as a possible response to an increased lipid overload. These findings provide new insights into the complex role of oxidative stress and mitochondrial redox status in the pathogenesis of the kidney in obesity and indicate that early oxidative stress-related changes, but not mitochondrial bioenergetic dysfunction, may contribute to the pathogenesis and development of obesity-linked chronic kidney diseases. PMID:21386058

The Spectrum of Mitochondrial Ultrastructural Defects in Mitochondrial Myopathy

PubMed Central

Vincent, Amy E.; Ng, Yi Shiau; White, Kathryn; Davey, Tracey; Mannella, Carmen; Falkous, Gavin; Feeney, Catherine; Schaefer, Andrew M.; McFarland, Robert; Gorman, Grainne S.; Taylor, Robert W.; Turnbull, Doug M.; Picard, Martin

2016-01-01

Mitochondrial functions are intrinsically linked to their morphology and membrane ultrastructure. Characterizing abnormal mitochondrial structural features may thus provide insight into the underlying pathogenesis of inherited and acquired mitochondrial diseases. Following a systematic literature review on ultrastructural defects in mitochondrial myopathy, we investigated skeletal muscle biopsies from seven subjects with genetically defined mtDNA mutations. Mitochondrial ultrastructure and morphology were characterized using two complimentary approaches: transmission electron microscopy (TEM) and serial block face scanning EM (SBF-SEM) with 3D reconstruction. Six ultrastructural abnormalities were identified including i) paracrystalline inclusions, ii) linearization of cristae and abnormal angular features, iii) concentric layering of cristae membranes, iv) matrix compartmentalization, v) nanotunelling, and vi) donut-shaped mitochondria. In light of recent molecular advances in mitochondrial biology, these findings reveal novel aspects of mitochondrial ultrastructure and morphology in human tissues with implications for understanding the mechanisms linking mitochondrial dysfunction to disease. PMID:27506553

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

Muscle remodeling in relation to blood supply: implications for seasonal changes in mitochondrial enzymes.

PubMed

McClelland, G B; Dalziel, A C; Fragoso, N M; Moyes, C D

2005-02-01

We investigated if seasonal changes in rainbow trout muscle energetics arise in response to seasonal changes in erythrocyte properties. We assessed if skeletal muscle mitochondrial enzymes changed (1) acutely in response to changes in erythrocyte abundance, or (2) seasonally when we altered the age profile of erythrocytes. Rainbow trout were treated with pheynylhydrazine, causing a 75% reduction in hematocrit within 4 days. After erythropoiesis had returned hematocrit to normal, treated and control fish were subjected to a seasonal cold acclimation regime to assess the impact of erythrocyte age on skeletal muscle remodeling. Anemia (i.e. phenylhydrazine treatment) did not alter the specific activities (U g(-1) tissue) of mitochondrial enzymes in white or red muscle. Anemic pretreatment did not alter the normal pattern of cold-induced mitochondrial proliferation in skeletal muscle, suggesting erythrocyte age was not an important influence on seasonal remodeling of muscle. Anemia and cold acclimation both induced a 25-30% increase in relative ventricular mass. The increase in relative ventricular mass with phenylhydrazine treatment was accompanied by a 35% increase in DNA content (mg DNA per ventricle), suggesting an increase in number of cells. In contrast, the increase in ventricular mass with cold temperature acclimation occurred without a change in DNA content (mg DNA per ventricle), suggesting an increase in cell size. Despite the major increases in relative ventricular mass, neither anemia nor seasonal acclimation had a major influence on the specific activities of a suite of mitochondrial enzymes in heart. Collectively, these studies argue against a role for erythrocyte dynamics in seasonal adaptive remodeling of skeletal muscle energetics.

[Cyclosporin A causes oxidative stress and mitochondrial dysfunction in renal tubular cells].

PubMed

Pérez de Hornedo, J; de Arriba, G; Calvino, M; Benito, S; Parra, T

2007-01-01

Reactive oxygen species (ROS) have been implicated in cyclosporin A (CsA) nephrotoxicity. As mitochondria are one of the main sources of ROS in cells, we evaluated the role of CsA in mitochondrial structure and function in LLC-PK1 cells. We incubated cells with CsA 1 microM for 24 hours and studies were performed with flow citometry and confocal microscopy. We studied mitochondrial NAD(P)H content, superoxide anion (O2.-) production (MitoSOX Red), oxidation of cardiolipin of inner mitochondrial membrane (NAO) and mitochondrial membrane potential (DIOC2(3)). Also we analyzed the intracellular ROS synthesis (H2DCF-DA) and reduced glutation (GSH) of cells. Our results showed that CsA decreased NAD(P)H and membrane potential, and increased O2.- in mitochondria. CsA also provoked oxidation of cardiolipin. Furthermore, CsA increased intracellular ROS production and decreased GSH content. These results suggest that CsA has crucial effects in mitochondria. CsA modified mitochondrial physiology through the decrease of antioxidant mitochondrial compounds as NAD(P)H and the dissipation of mitochondrial membrane potential and increase of oxidants as O2.-. Also, CsA alters lipidic structure of inner mitochondrial membrane through the oxidation of cardiolipin. These effects trigger a chain of events that favour intracellular synthesis of ROS and depletion of GSH that can compromise cellular viability. Nephrotoxic cellular effects of CsA can be explained, at least in part, through its influence on mitochondrial functionalism.

Mitochondrial pyruvate transport: a historical perspective and future research directions

PubMed Central

McCommis, Kyle S.; Finck, Brian N.

2015-01-01

Pyruvate is the end-product of glycolysis, a major substrate for oxidative metabolism, and a branching point for glucose, lactate, fatty acid and amino acid synthesis. The mitochondrial enzymes that metabolize pyruvate are physically separated from cytosolic pyruvate pools and rely on a membrane transport system to shuttle pyruvate across the impermeable inner mitochondrial membrane (IMM). Despite long-standing acceptance that transport of pyruvate into the mitochondrial matrix by a carrier-mediated process is required for the bulk of its metabolism, it has taken almost 40 years to determine the molecular identity of an IMM pyruvate carrier. Our current understanding is that two proteins, mitochondrial pyruvate carriers MPC1 and MPC2, form a hetero-oligomeric complex in the IMM to facilitate pyruvate transport. This step is required for mitochondrial pyruvate oxidation and carboxylation – critical reactions in intermediary metabolism that are dysregulated in several common diseases. The identification of these transporter constituents opens the door to the identification of novel compounds that modulate MPC activity, with potential utility for treating diabetes, cardiovascular disease, cancer, neurodegenerative diseases, and other common causes of morbidity and mortality. The purpose of the present review is to detail the historical, current and future research investigations concerning mitochondrial pyruvate transport, and discuss the possible consequences of altered pyruvate transport in various metabolic tissues. PMID:25748677

cis-4-Decenoic and decanoic acids impair mitochondrial energy, redox and Ca(2+) homeostasis and induce mitochondrial permeability transition pore opening in rat brain and liver: Possible implications for the pathogenesis of MCAD deficiency.

PubMed

Amaral, Alexandre Umpierrez; Cecatto, Cristiane; da Silva, Janaína Camacho; Wajner, Alessandro; Godoy, Kálita Dos Santos; Ribeiro, Rafael Teixeira; Wajner, Moacir

2016-09-01

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is biochemically characterized by tissue accumulation of octanoic (OA), decanoic (DA) and cis-4-decenoic (cDA) acids, as well as by their carnitine by-products. Untreated patients present episodic encephalopathic crises and biochemical liver alterations, whose pathophysiology is poorly known. We investigated the effects of OA, DA, cDA, octanoylcarnitine (OC) and decanoylcarnitine (DC) on critical mitochondrial functions in rat brain and liver. DA and cDA increased resting respiration and diminished ADP- and CCCP-stimulated respiration and complexes II-III and IV activities in both tissues. The data indicate that these compounds behave as uncouplers and metabolic inhibitors of oxidative phosphorylation. Noteworthy, metabolic inhibition was more evident in brain as compared to liver. DA and cDA also markedly decreased mitochondrial membrane potential, NAD(P)H content and Ca(2+) retention capacity in Ca(2+)-loaded brain and liver mitochondria. The reduction of Ca(2+) retention capacity was more pronounced in liver and totally prevented by cyclosporine A and ADP, as well as by ruthenium red, demonstrating the involvement of mitochondrial permeability transition (mPT) and Ca(2+). Furthermore, cDA induced lipid peroxidation in brain and liver mitochondria and increased hydrogen peroxide formation in brain, suggesting the participation of oxidative damage in cDA-induced alterations. Interestingly, OA, OC and DC did not alter the evaluated parameters, implying lower toxicity for these compounds. Our results suggest that DA and cDA, in contrast to OA and medium-chain acylcarnitines, disturb important mitochondrial functions in brain and liver by multiple mechanisms that are possibly involved in the neuropathology and liver alterations observed in MCAD deficiency. Copyright © 2016 Elsevier B.V. All rights reserved.

Thymidine kinase 2 deficiency-induced mitochondrial DNA depletion causes abnormal development of adipose tissues and adipokine levels in mice.

PubMed

Villarroya, Joan; Dorado, Beatriz; Vilà, Maya R; Garcia-Arumí, Elena; Domingo, Pere; Giralt, Marta; Hirano, Michio; Villarroya, Francesc

2011-01-01

Mammal adipose tissues require mitochondrial activity for proper development and differentiation. The components of the mitochondrial respiratory chain/oxidative phosphorylation system (OXPHOS) are encoded by both mitochondrial and nuclear genomes. The maintenance of mitochondrial DNA (mtDNA) is a key element for a functional mitochondrial oxidative activity in mammalian cells. To ascertain the role of mtDNA levels in adipose tissue, we have analyzed the alterations in white (WAT) and brown (BAT) adipose tissues in thymidine kinase 2 (Tk2) H126N knockin mice, a model of TK2 deficiency-induced mtDNA depletion. We observed respectively severe and moderate mtDNA depletion in TK2-deficient BAT and WAT, showing both tissues moderate hypotrophy and reduced fat accumulation. Electron microscopy revealed altered mitochondrial morphology in brown but not in white adipocytes from TK2-deficient mice. Although significant reduction in mtDNA-encoded transcripts was observed both in WAT and BAT, protein levels from distinct OXPHOS complexes were significantly reduced only in TK2-deficient BAT. Accordingly, the activity of cytochrome c oxidase was significantly lowered only in BAT from TK2-deficient mice. The analysis of transcripts encoding up to fourteen components of specific adipose tissue functions revealed that, in both TK2-deficient WAT and BAT, there was a consistent reduction of thermogenesis related gene expression and a severe reduction in leptin mRNA. Reduced levels of resistin mRNA were found in BAT from TK2-deficient mice. Analysis of serum indicated a dramatic reduction in circulating levels of leptin and resistin. In summary, our present study establishes that mtDNA depletion leads to a moderate impairment in mitochondrial respiratory function, especially in BAT, causes substantial alterations in WAT and BAT development, and has a profound impact in the endocrine properties of adipose tissues. © 2011 Villarroya et al.

Thymidine Kinase 2 Deficiency-Induced Mitochondrial DNA Depletion Causes Abnormal Development of Adipose Tissues and Adipokine Levels in Mice

PubMed Central

Villarroya, Joan; Dorado, Beatriz; Vilà, Maya R.; Garcia-Arumí, Elena; Domingo, Pere; Giralt, Marta; Hirano, Michio; Villarroya, Francesc

2011-01-01

Mammal adipose tissues require mitochondrial activity for proper development and differentiation. The components of the mitochondrial respiratory chain/oxidative phosphorylation system (OXPHOS) are encoded by both mitochondrial and nuclear genomes. The maintenance of mitochondrial DNA (mtDNA) is a key element for a functional mitochondrial oxidative activity in mammalian cells. To ascertain the role of mtDNA levels in adipose tissue, we have analyzed the alterations in white (WAT) and brown (BAT) adipose tissues in thymidine kinase 2 (Tk2) H126N knockin mice, a model of TK2 deficiency-induced mtDNA depletion. We observed respectively severe and moderate mtDNA depletion in TK2-deficient BAT and WAT, showing both tissues moderate hypotrophy and reduced fat accumulation. Electron microscopy revealed altered mitochondrial morphology in brown but not in white adipocytes from TK2-deficient mice. Although significant reduction in mtDNA-encoded transcripts was observed both in WAT and BAT, protein levels from distinct OXPHOS complexes were significantly reduced only in TK2-deficient BAT. Accordingly, the activity of cytochrome c oxidase was significantly lowered only in BAT from TK2-deficient mice. The analysis of transcripts encoding up to fourteen components of specific adipose tissue functions revealed that, in both TK2-deficient WAT and BAT, there was a consistent reduction of thermogenesis related gene expression and a severe reduction in leptin mRNA. Reduced levels of resistin mRNA were found in BAT from TK2-deficient mice. Analysis of serum indicated a dramatic reduction in circulating levels of leptin and resistin. In summary, our present study establishes that mtDNA depletion leads to a moderate impairment in mitochondrial respiratory function, especially in BAT, causes substantial alterations in WAT and BAT development, and has a profound impact in the endocrine properties of adipose tissues. PMID:22216345

LA SYNTHÈSE DE L'ADN MITOCHONDRIAL CHEZ TETRAHYMENA PYRIFORMIS

PubMed Central

Charret, Renée; André, Jean

1968-01-01

Electron microscopic radioautography has been used to study the synthesis of mitochondrial DNA after incorporation of thymidine-3H by cultures in logarithmic phase of Tetrahymena pyriformis during periods ranging from 15 min to 12 hr. The great majority of silver grains are distributed over the macronuclei, the micronuclei, and the mitochondria. The intensity of the label over the entire mitochondrial population is a function of the length of the incubation period within the time interval considered. The intensity of the mitochondrial label was compared with that of the nuclear label. Mitochondria incorporate at the same rate whether the nuclei are synthesizing or not. This persistence of mitochondrial incorporation in the absence of nuclear incorporation excludes the hypothesis of a nuclear origin for mitochondrial DNA. We are not able to determine whether the apparent continuity of synthesis in the entire mitochondrial population of a cell actually represents a series of asynchronous discontinuities. PMID:5677970

Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis.

PubMed

Morris, E Matthew; Meers, Grace M E; Koch, Lauren G; Britton, Steven L; Fletcher, Justin A; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C; Ibdah, Jamal A; Rector, R Scott; Thyfault, John P

2016-10-01

Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity.

Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis

PubMed Central

Morris, E. Matthew; Meers, Grace M. E.; Koch, Lauren G.; Britton, Steven L.; Fletcher, Justin A.; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C.; Ibdah, Jamal A.; Rector, R. Scott

2016-01-01

Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity. PMID:27600823

Mitochondrial DNA polymorphism in a maternal lineage of Holstein cows.

PubMed Central

Hauswirth, W W; Laipis, P J

1982-01-01

Two mitochondrial genotypes are shown to exist within one Holstein cow maternal lineage. They were detected by the appearance of an extra Hae III recognition site in one genotype. The nucleotide sequence of this region has been determined and the genotypes are distinguished by an adenine/guanine base transition which creates the new Hae III site. This point mutation occurs within an open reading frame at the third position of a glycine codon and therefore does not alter the amino acid sequence. The present pattern of genotypes within the lineage demands that multiple shifts between genotypes must have occurred within the past 20 years with the most rapid shift taking place in no more than 4 years and indicates that mitochondrial DNA polymorphism can occur between maternally related mammals. The process that gave rise to different genotypes in one lineage is clearly of fundamental importance in understanding intraspecific mitochondrial polymorphism and evolution in mammals. Several potential mechanisms for rapid mitochondrial DNA variation are discussed in light of these results. Images PMID:6289312

Detection of heteroplasmy in individual mitochondrial particles

PubMed Central

Poe, Bobby G.; Duffy, Ciarán F.; Greminger, Michael A.; Nelson, Bradley J.

2011-01-01

Mitochondrial DNA (mtDNA) mutations have been associated with disease and aging. Since each cell has thousands of mtDNA copies, clustered into nucleoids of five to ten mtDNA molecules each, determining the effects of a given mtDNA mutation and their connection with disease phenotype is not straightforward. It has been postulated that heteroplasmy (coexistence of mutated and wild-type DNA) follows simple probability rules dictated by the random distribution of mtDNA molecules at the nucleoid level. This model has been used to explain how mutation levels correlate with the onset of disease phenotype and loss of cellular function. Nonetheless, experimental evidence of heteroplasmy at the nucleoid level is scarce. Here, we report a new method to determine heteroplasmy of individual mitochondrial particles containing one or more nucleoids. The method uses capillary cytometry with laser-induced fluorescence detection to detect individual mitochondrial particles stained with PicoGreen, which makes it possible to quantify the mtDNA copy number of each particle. After detection, one or more particles are collected into polymerase chain reaction (PCR) wells and then subjected to real-time multiplexed PCR amplification. This PCR strategy is suitable to obtain the relative abundance of mutated and wild-type mtDNA. The results obtained here indicate that individual mitochondrial particles and nucleoids contained within these particles are not heteroplasmic. The results presented here suggest that current models of mtDNA segregation and distribution (i.e., heteroplasmic nucleoids) need further consideration. PMID:20467729

The Homeobox Protein CEH-23 Mediates Prolonged Longevity in Response to Impaired Mitochondrial Electron Transport Chain in C. elegans

PubMed Central

Walter, Ludivine; Baruah, Aiswarya; Chang, Hsin-Wen; Pace, Heather Mae; Lee, Siu Sylvia

2011-01-01

Recent findings indicate that perturbations of the mitochondrial electron transport chain (METC) can cause extended longevity in evolutionarily diverse organisms. To uncover the molecular basis of how altered METC increases lifespan in C. elegans, we performed an RNAi screen and revealed that three predicted transcription factors are specifically required for the extended longevity of mitochondrial mutants. In particular, we demonstrated that the nuclear homeobox protein CEH-23 uniquely mediates the longevity but not the slow development, reduced brood size, or resistance to oxidative stress associated with mitochondrial mutations. Furthermore, we showed that ceh-23 expression levels are responsive to altered METC, and enforced overexpression of ceh-23 is sufficient to extend lifespan in wild-type background. Our data point to mitochondria-to-nucleus communications to be key for longevity determination and highlight CEH-23 as a novel longevity factor capable of responding to mitochondrial perturbations. These findings provide a new paradigm for how mitochondria impact aging and age-dependent diseases. PMID:21713031

Evidence and age-related distribution of mtDNA D-loop point mutations in skeletal muscle from healthy subjects and mitochondrial patients.

PubMed

Del Bo, Roberto; Bordoni, Andreina; Martinelli Boneschi, Filippo; Crimi, Marco; Sciacco, Monica; Bresolin, Nereo; Scarlato, Guglielmo; Comi, Giacomo Pietri

2002-10-15

The progressive accumulation of mitochondrial DNA (mtDNA) alterations, ranging from single mutations to large-scale deletions, in both the normal ageing process and pathological conditions is a relevant phenomenon in terms of frequency and heteroplasmic degree. Recently, two point mutations (A189G and T408A) within the Displacement loop (D-loop) region, the control region for mtDNA replication, were shown to occur in skeletal muscles from aged individuals. We evaluated the presence and the heteroplasmy levels of these two mutations in muscle biopsies from 91 unrelated individuals of different ages (21 healthy subjects and 70 patients affected by mitochondrial encephalomyopathies). Overall, both mutations significantly accumulate with age. However, a different relationship was discovered among the different subgroups of patients: a higher number of A189G positive subjects younger than 53 years was detected in the subgroup of multiple-deleted patients; furthermore, a trend towards an increased risk for the mutations was evidenced among patients carrying multiple deletions when compared to healthy controls. These findings support the idea that a common biological mechanism determines the accumulation of somatic point mutations in the D-loop region, both in healthy subjects and in mitochondrial myopathy patients. At the same time, it appears that disorders caused by mutations of nuclear genes controlling mtDNA replication (the "mtDNA multiple deletions" syndromes) present a temporal advantage to mutate in the D-loop region. This observation may be relevant to the definition of the molecular pathogenesis of these latter syndromes. Copyright 2002 Elsevier Science B.V.

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.

Associations of mitochondrial haplogroups and mitochondrial DNA copy numbers with end-stage renal disease in a Han population.

PubMed

Zhang, Yuheng; Zhao, Ying; Wen, Shuzhen; Yan, Rengna; Yang, Qinglan; Chen, Huimei

2017-09-01

Mitochondrial DNA (mtDNA) is closely related to mitochondrion function, and variations have been suggested to be involved in pathogenesis of complex diseases. The present study sought to elucidate mitochondrial haplogroups and mtDNA copy number in end-stage renal disease (ESRD) in a Han population. First, the mitochondrial haplogroups of 37 ESRD patients were clustered into several haplogroups, and haplogroup A & D were taken as the candidate risk haplogroups for ESRD. Second, the frequencies of A and D were assessed in 344 ESRD patients and 438 healthy controls, respectively. Haplogroup D was found to be risk maker for ESRD in young subjects (<30 years) with an OR of 2.274. Finally, intracellular and cell-free mtDNA copy numbers were evaluated with quantitative-PCR. The ESRD patients exhibited greater cell-free mtDNA contents than the healthy controls but less intracellular mtDNA. Haplogroup D exhibited a further increase in cell-free mtDNA content and a decrease in intracellular mtDNA content among the ESRDs patients. Our findings suggest that mtNDA haplogroup D may contributes to pathogenesis of early-onset ESRD through alterations of mtDNA copy numbers.

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

Mitochondrial oxidative stress and cardiac ageing.

PubMed

Martín-Fernández, Beatriz; Gredilla, Ricardo

According with different international organizations, cardiovascular diseases are becoming the first cause of death in western countries. Although exposure to different risk factors, particularly those related to lifestyle, contribute to the etiopathogenesis of cardiac disorders, the increase in average lifespan and aging are considered major determinants of cardiac diseases events. Mitochondria and oxidative stress have been pointed out as relevant factors both in heart aging and in the development of cardiac diseases such as heart failure, cardiac hypertrophy and diabetic cardiomyopathy. During aging, cellular processes related with mitochondrial function, such as bioenergetics, apoptosis and inflammation are altered leading to cardiac dysfunction. Increasing our knowledge about the mitochondrial mechanisms related with the aging process, will provide new strategies in order to improve this process, particularly the cardiovascular ones. Copyright © 2017 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

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.

Mitochondrial pyruvate transport in working guinea-pig heart. Work-related vs. carrier-mediated control of pyruvate oxidation.

PubMed

Bünger, R; Mallet, R T

1993-09-19

Myocardial pyruvate oxidation is work- or calcium-load-related, but control of pyruvate dehydrogenase (PDH) by the specific mitochondrial pyruvate transporter has also been proposed. To test the transport hypothesis distribution of pyruvate across the cell membrane as well as rates of mitochondrial pyruvate net transport plus oxidation were examined in isolated perfused but stable and physiologically working guinea-pig hearts. 150 microM-1.2 mM alpha-cyanohydroxycinnamate proved to specifically block mitochondrial pyruvate uptake in these hearts. When perfusate glucose as cytosolic pyruvate precursor was supplied in combination with octanoate (0.2 or 0.5 mM) as diffusible alternative fatty acid substrate, alpha-cyanohydroxycinnamate produced up to 20- and 3-fold increases in pyruvate and lactate efflux, respectively. Cinnamates did not alter myocardial hemodynamics nor sarcolemmal pyruvate and lactate export. In contrast the tested concentrations of cinnamate produced reversible, dose-dependent decreases in 14CO2 production from [1-14C]pyruvate or [U-14C]glucose by inhibiting mitochondrial pyruvate uptake. Linear least-squares estimates of available cinnamate-sensitive total pyruvate transport potential yielded rates close to 110 mumol/min per g dry mass at S0.5 approximately 120 microM, which compared reasonably well with literature values from isolated cardiac mitochondria. This transport potential was severalfold larger than total extractable myocardial PDH activity of approximately 32 mumol/min per g dry mass at 37 degrees C. Even when cytosolic pyruvate levels were in the lower physiologic range of about 90 microM, pyruvate oxidation readily kept pace with mitochondrial respiration over a wide range of workload and inotropism. Furthermore, dichloroacetate, a selective activator of PDH, stimulated pyruvate oxidation without affecting myocardial O2 consumption, regardless of the metabolic or inotropic state of the hearts. Consequently, little or no regulatory

Aging Neural Progenitor Cells Have Decreased Mitochondrial Content and Lower Oxidative Metabolism*

PubMed Central

Stoll, Elizabeth A.; Cheung, Willy; Mikheev, Andrei M.; Sweet, Ian R.; Bielas, Jason H.; Zhang, Jing; Rostomily, Robert C.; Horner, Philip J.

2011-01-01

Although neurogenesis occurs in discrete areas of the adult mammalian brain, neural progenitor cells (NPCs) produce fewer new neurons with age. To characterize the molecular changes that occur during aging, we performed a proteomic comparison between primary-cultured NPCs from the young adult and aged mouse forebrain. This analysis yielded changes in proteins necessary for cellular metabolism. Mitochondrial quantity and oxygen consumption rates decrease with aging, although mitochondrial DNA in aged NPCs does not have increased mutation rates. In addition, aged cells are resistant to the mitochondrial inhibitor rotenone and proliferate in response to lowered oxygen conditions. These results demonstrate that aging NPCs display an altered metabolic phenotype, characterized by a coordinated shift in protein expression, subcellular structure, and metabolic physiology. PMID:21900249

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.

Brain-derived neurotrophic factor (BDNF)-induced mitochondrial motility arrest and presynaptic docking contribute to BDNF-enhanced synaptic transmission.

PubMed

Su, Bo; Ji, Yun-Song; Sun, Xu-lu; Liu, Xiang-Hua; Chen, Zhe-Yu

2014-01-17

Appropriate mitochondrial transport and distribution are essential for neurons because of the high energy and Ca(2+) buffering requirements at synapses. Brain-derived neurotrophic factor (BDNF) plays an essential role in regulating synaptic transmission and plasticity. However, whether and how BDNF can regulate mitochondrial transport and distribution are still unclear. Here, we find that in cultured hippocampal neurons, application of BDNF for 15 min decreased the percentage of moving mitochondria in axons, a process dependent on the activation of the TrkB receptor and its downstream PI3K and phospholipase-Cγ signaling pathways. Moreover, the BDNF-induced mitochondrial stopping requires the activation of transient receptor potential canonical 3 and 6 (TRPC3 and TRPC6) channels and elevated intracellular Ca(2+) levels. The Ca(2+) sensor Miro1 plays an important role in this process. Finally, the BDNF-induced mitochondrial stopping leads to the accumulation of more mitochondria at presynaptic sites. Mutant Miro1 lacking the ability to bind Ca(2+) prevents BDNF-induced mitochondrial presynaptic accumulation and synaptic transmission, suggesting that Miro1-mediated mitochondrial motility is involved in BDNF-induced mitochondrial presynaptic docking and neurotransmission. Together, these data suggest that mitochondrial transport and distribution play essential roles in BDNF-mediated synaptic transmission.

Prenatal iron deficiency causes sex-dependent mitochondrial dysfunction and oxidative stress in fetal rat kidneys and liver.

PubMed

Woodman, Andrew G; Mah, Richard; Keddie, Danae; Noble, Ronan M N; Panahi, Sareh; Gragasin, Ferrante S; Lemieux, Hélène; Bourque, Stephane L

2018-06-01

Prenatal iron deficiency alters fetal developmental trajectories, which results in persistent changes in organ function. Here, we studied the effects of prenatal iron deficiency on fetal kidney and liver mitochondrial function. Pregnant Sprague-Dawley rats were fed partially or fully iron-restricted diets to induce a state of moderate or severe iron deficiency alongside iron-replete control rats. We assessed mitochondrial function via high-resolution respirometry and reactive oxygen species generation via fluorescence microscopy on gestational d 21. Hemoglobin levels were reduced in dams in the moderate (-31%) and severe groups (-54%) compared with controls, which was accompanied by 55% reductions in fetal hemoglobin levels in both moderate and severe groups versus controls. Male iron-deficient kidneys exhibited globally reduced mitochondrial content and respiration, as well as increased cytosolic superoxide and decreased NO. Female iron-deficient kidneys exhibited complex II down-regulation and increased mitochondrial oxidative stress. Male iron-deficient livers exhibited reduced complex IV respiration and increased cytosolic superoxide, whereas female liver tissues exhibited no alteration in oxidant levels or mitochondrial function. These findings indicate that prenatal iron deficiency causes changes in mitochondrial content and function as well as oxidant status in a sex- and organ-dependent manner, which may be an important mechanism that underlies the programming of cardiovascular disease.-Woodman, A. G., Mah, R., Keddie, D., Noble, R. M. N., Panahi, S., Gragasin, F. S., Lemieux, H., Bourque, S. L. Prenatal iron deficiency causes sex-dependent mitochondrial dysfunction and oxidative stress in fetal rat kidneys and liver.

Overexpression of Mitochondrial Phosphate Transporter 3 Severely Hampers Plant Development through Regulating Mitochondrial Function in Arabidopsis.

PubMed

Jia, Fengjuan; Wan, Xiaomin; Zhu, Wei; Sun, Dan; Zheng, Chengchao; Liu, Pei; Huang, Jinguang

2015-01-01

Mitochondria are abundant and important organelles present in nearly all eukaryotic cells, which maintain metabolic communication with the cytosol through mitochondrial carriers. The mitochondrial membrane localized phosphate transporter (MPT) plays vital roles in diverse development and signaling processes, especially the ATP biosynthesis. Among the three MPT genes in Arabidopsis genome, AtMPT3 was proven to be a major member, and its overexpression gave rise to multiple developmental defects including curly leaves with deep color, dwarfed stature, and reduced fertility. Transcript profiles revealed that genes involved in plant metabolism, cellular redox homeostasis, alternative respiration pathway, and leaf and flower development were obviously altered in AtMPT3 overexpression (OEMPT3) plants. Moreover, OEMPT3 plants also accumulated higher ATP content, faster respiration rate and more reactive oxygen species (ROS) than wild type plants. Overall, our studies showed that AtMPT3 was indispensable for Arabidopsis normal growth and development, and provided new sights to investigate its possible regulation mechanisms.

Overexpression of Mitochondrial Phosphate Transporter 3 Severely Hampers Plant Development through Regulating Mitochondrial Function in Arabidopsis

PubMed Central

Jia, Fengjuan; Wan, Xiaomin; Zhu, Wei; Sun, Dan; Zheng, Chengchao; Liu, Pei; Huang, Jinguang

2015-01-01

Mitochondria are abundant and important organelles present in nearly all eukaryotic cells, which maintain metabolic communication with the cytosol through mitochondrial carriers. The mitochondrial membrane localized phosphate transporter (MPT) plays vital roles in diverse development and signaling processes, especially the ATP biosynthesis. Among the three MPT genes in Arabidopsis genome, AtMPT3 was proven to be a major member, and its overexpression gave rise to multiple developmental defects including curly leaves with deep color, dwarfed stature, and reduced fertility. Transcript profiles revealed that genes involved in plant metabolism, cellular redox homeostasis, alternative respiration pathway, and leaf and flower development were obviously altered in AtMPT3 overexpression (OEMPT3) plants. Moreover, OEMPT3 plants also accumulated higher ATP content, faster respiration rate and more reactive oxygen species (ROS) than wild type plants. Overall, our studies showed that AtMPT3 was indispensable for Arabidopsis normal growth and development, and provided new sights to investigate its possible regulation mechanisms. PMID:26076137

Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle.

PubMed

Whitfield, J; Ludzki, A; Heigenhauser, G J F; Senden, J M G; Verdijk, L B; van Loon, L J C; Spriet, L L; Holloway, G P

2016-01-15

Oral consumption of nitrate (NO3(-)) in beetroot juice has been shown to decrease the oxygen cost of submaximal exercise; however, the mechanism of action remains unresolved. We supplemented recreationally active males with beetroot juice to determine if this altered mitochondrial bioenergetics. Despite reduced submaximal exercise oxygen consumption, measures of mitochondrial coupling and respiratory efficiency were not altered in muscle. In contrast, rates of mitochondrial hydrogen peroxide (H2O2) emission were increased in the absence of markers of lipid or protein oxidative damage. These results suggest that improvements in mitochondrial oxidative metabolism are not the cause of beetroot juice-mediated improvements in whole body oxygen consumption. Ingestion of sodium nitrate (NO3(-)) simultaneously reduces whole body oxygen consumption (V̇O2) during submaximal exercise while improving mitochondrial efficiency, suggesting a causal link. Consumption of beetroot juice (BRJ) elicits similar decreases in V̇O2 but potential effects on the mitochondria remain unknown. Therefore we examined the effects of 7-day supplementation with BRJ (280 ml day(-1), ∼26 mmol NO3(-)) in young active males (n = 10) who had muscle biopsies taken before and after supplementation for assessments of mitochondrial bioenergetics. Subjects performed 20 min of cycling (10 min at 50% and 70% V̇O2 peak) 48 h before 'Pre' (baseline) and 'Post' (day 5 of supplementation) biopsies. Whole body V̇O2 decreased (P < 0.05) by ∼3% at 70% V̇O2 peak following supplementation. Mitochondrial respiration in permeabilized muscle fibres showed no change in leak respiration, the content of proteins associated with uncoupling (UCP3, ANT1, ANT2), maximal substrate-supported respiration, or ADP sensitivity (apparent Km). In addition, isolated subsarcolemmal and intermyofibrillar mitochondria showed unaltered assessments of mitochondrial efficiency, including ADP consumed/oxygen consumed (P/O ratio

An Essential Role for COPI in mRNA Localization to Mitochondria and Mitochondrial Function.

PubMed

Zabezhinsky, Dmitry; Slobodin, Boris; Rapaport, Doron; Gerst, Jeffrey E

2016-04-19

Nuclear-encoded mRNAs encoding mitochondrial proteins (mMPs) can localize directly to the mitochondrial surface, yet how mMPs target mitochondria and whether RNA targeting contributes to protein import into mitochondria and cellular metabolism are unknown. Here, we show that the COPI vesicle coat complex is necessary for mMP localization to mitochondria and mitochondrial function. COPI inactivation leads to reduced mMP binding to COPI itself, resulting in the dissociation of mMPs from mitochondria, a reduction in mitochondrial membrane potential, a decrease in protein import in vivo and in vitro, and severe deficiencies in mitochondrial respiration. Using a model mMP (OXA1), we observed that COPI inactivation (or mutation of the potential COPI-interaction site) led to altered mRNA localization and impaired cellular respiration. Overall, COPI-mediated mMP targeting is critical for mitochondrial protein import and function, and transcript delivery to the mitochondria or endoplasmic reticulum is regulated by cis-acting RNA sequences and trans-acting proteins. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Soy lecithin interferes with mitochondrial function in frozen-thawed ram spermatozoa.

PubMed

Del Valle, I; Gómez-Durán, A; Holt, W V; Muiño-Blanco, T; Cebrián-Pérez, J A

2012-01-01

Egg yolk and milk are the 2 major membrane cryoprotectants commonly used in freezing media for the long-term preservation of semen (alone or in combination with others). However, in recent years, there have been increasing arguments against the use of egg yolk or milk because of the risk of introducing diseases through the use of cryopreserved semen. In this study, we analyzed the protective effect of lecithin as an alternative to egg yolk for the cryopreservation of ram semen, using a range of functional markers for sperm viability, motility, apoptosis, and mitochondrial functionality analyses (mitochondrial inner membrane surface [MIMS], mitochondrial inner membrane potential [MIMP], and cell membrane potential) as methods of assessment in samples diluted in 3 different media: Tris-citrate-glucose as control and 2 media supplemented with soy lecithin or egg yolk. The results showed that lecithin was able to effectively protect certain sperm quality characteristics against freezing-induced damage. However, lecithin induced loss of mitochondrial membrane potential or mitochondrial loss that was not reflected by modifications in sperm motility in fresh semen. MIMS and MIMP values decreased in thawed lecithin-treated samples, concomitant with a lower (P < .05) percentage of total and progressively motile cells, compared with those in egg yolk-containing samples. Further incubation of thawed samples revealed changes in motility and mitochondrial functionality that otherwise would not have been detected. These results indicated that lecithin may have affected the inner mitochondrial membrane in frozenthawed spermatozoa and confirmed that sublethal damages that seriously affect sperm functionality, not detected by classic sperm quality analyses, can be evidenced by changes in the inner mitochondrial membrane surface. These findings strengthen the relationship between mitochondrial membrane potential and motility and show that the mitochondrial alterations induced by the

Mitochondrial Dysfunction in Parkinson's Disease.

PubMed

Moon, Hyo Eun; Paek, Sun Ha

2015-06-01

Parkinson's disease (PD) is characterized by the selective loss of dopaminergic neurons of the substantia nigra pars compacta (SNc) with motor and nonmotor symptoms. Defective mitochondrial function and increased oxidative stress (OS) have been demonstrated as having an important role in PD pathogenesis, although the underlying mechanism is not clear. The etiopathogenesis of sporadic PD is complex with variable contributions of environmental factors and genetic susceptibility. Both these factors influence various mitochondrial aspects, including their life cycle, bioenergetic capacity, quality control, dynamic changes of morphology and connectivity (fusion, fission), subcellular distribution (transport), and the regulation of cell death pathways. Mitochondrial dysfunction has mainly been reported in various non-dopaminergic cells and tissue samples from human patients as well as transgenic mouse and fruit fly models of PD. Thus, the mitochondria represent a highly promising target for the development of PD biomarkers. However, the limited amount of dopaminergic neurons prevented investigation of their detailed study. For the first time, we established human telomerase reverse transcriptase (hTERT)-immortalized wild type, idiopathic and Parkin deficient mesenchymal stromal cells (MSCs) isolated from the adipose tissues of PD patients, which could be used as a good cellular model to evaluate mitochondrial dysfunction for the better understanding of PD pathology and for the development of early diagnostic markers and effective therapy targets of PD. In this review, we examine evidence for the roles of mitochondrial dysfunction and increased OS in the neuronal loss that leads to PD and discuss how this knowledge further improve the treatment for patients with PD.

Mitochondrial Insult in a Parkinson's like symptoms model

NASA Astrophysics Data System (ADS)

Carrizales, Julio; Cantu, Manuel; Plas, Daniel; Daniel Plas Lab Team, Dr.

2014-03-01

Healthy cells require healthy mitochondria. If these organelles are damaged, many health consequences follow. For example, Parkinson's Disease (PD) is a major neurodegenerative disorder of unknown cause, but much evidence points to the mitochondrion as a key player in the onset of this disease. PD has been studied in animal models challenged with toxins that target the mitochondria. In our work, we have used the pesticide, Rotenone, a known inhibitor of protein Complex I in the mitochondrial electron transport chain. When this toxin is applied to the freshwater mollusk, Lymnaea stagnalis, or pond snail, severe motor deficits ensue. In this project, we are studying the direct effects of this toxin on mitochondrial structure and physiology. We expected that the morphology of the organelle may be altered. In addition, it is likely that the mitochondrial membrane potential necessary for normal function may decrease as the electron transport loses the ability to move protons from the matrix to the intermembrane space. we also are going to use Electrophysiology to compare and Identify the difference of the electrical signaling among healthy and unhealthy neurons. HHMI

MitoBreak: the mitochondrial DNA breakpoints database.

PubMed

Damas, Joana; Carneiro, João; Amorim, António; Pereira, Filipe

2014-01-01

Mitochondrial DNA (mtDNA) rearrangements are key events in the development of many diseases. Investigations of mtDNA regions affected by rearrangements (i.e. breakpoints) can lead to important discoveries about rearrangement mechanisms and can offer important clues about the causes of mitochondrial diseases. Here, we present the mitochondrial DNA breakpoints database (MitoBreak; http://mitobreak.portugene.com), a free, web-accessible comprehensive list of breakpoints from three classes of somatic mtDNA rearrangements: circular deleted (deletions), circular partially duplicated (duplications) and linear mtDNAs. Currently, MitoBreak contains >1400 mtDNA rearrangements from seven species (Homo sapiens, Mus musculus, Rattus norvegicus, Macaca mulatta, Drosophila melanogaster, Caenorhabditis elegans and Podospora anserina) and their associated phenotypic information collected from nearly 400 publications. The database allows researchers to perform multiple types of data analyses through user-friendly interfaces with full or partial datasets. It also permits the download of curated data and the submission of new mtDNA rearrangements. For each reported case, MitoBreak also documents the precise breakpoint positions, junction sequences, disease or associated symptoms and links to the related publications, providing a useful resource to study the causes and consequences of mtDNA structural alterations.

The use of high-throughput screening techniques to evaluate mitochondrial toxicity.

PubMed

Wills, Lauren P

2017-11-01

Toxicologists and chemical regulators depend on accurate and effective methods to evaluate and predict the toxicity of thousands of current and future compounds. Robust high-throughput screening (HTS) experiments have the potential to efficiently test large numbers of chemical compounds for effects on biological pathways. HTS assays can be utilized to examine chemical toxicity across multiple mechanisms of action, experimental models, concentrations, and lengths of exposure. Many agricultural, industrial, and pharmaceutical chemicals classified as harmful to human and environmental health exert their effects through the mechanism of mitochondrial toxicity. Mitochondrial toxicants are compounds that cause a decrease in the number of mitochondria within a cell, and/or decrease the ability of mitochondria to perform normal functions including producing adenosine triphosphate (ATP) and maintaining cellular homeostasis. Mitochondrial dysfunction can lead to apoptosis, necrosis, altered metabolism, muscle weakness, neurodegeneration, decreased organ function, and eventually disease or death of the whole organism. The development of HTS techniques to identify mitochondrial toxicants will provide extensive databases with essential connections between mechanistic mitochondrial toxicity and chemical structure. Computational and bioinformatics approaches can be used to evaluate compound databases for specific chemical structures associated with toxicity, with the goal of developing quantitative structure-activity relationship (QSAR) models and mitochondrial toxicophores. Ultimately these predictive models will facilitate the identification of mitochondrial liabilities in consumer products, industrial compounds, pharmaceuticals and environmental hazards. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamin-Related Protein 1 and Mitochondrial Fragmentation in Neurodegenerative Diseases

PubMed Central

Reddy, P. Hemachandra; Reddy, Tejaswini P.; Manczak, Maria; Calkins, Marcus J.; Shirendeb, Ulziibat; Mao, Peizhong

2010-01-01

The purpose of this article is to review the recent developments of abnormal mitochondrial dynamics, mitochondrial fragmentation, and neuronal damage in neurodegenerative diseases, including Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis. The GTPase family of proteins, including fission proteins, dynamin related protein 1 (Drp1), mitochondrial fission 1 (Fis1), and fusion proteins (Mfn1, Mfn2 and Opa1) are essential to maintain mitochondrial fission and fusion balance, and to provide necessary adenosine triphosphate to neurons. Among these, Drp1 is involved in several important aspects of mitochondria, including shape, size, distribution, remodeling, and maintenance of X in mammalian cells. In addition, recent advancements in molecular, cellular, electron microscopy, and confocal imaging studies revealed that Drp1 is associated with several cellular functions, including mitochondrial and peroxisomal fragmentation, phosphorylation, SUMOylation, ubiquitination, and cell death. In the last two decades, tremendous progress has been made in researching mitochondrial dynamics, in yeast, worms, and mammalian cells; and this research has provided evidence linking Drp1 to neurodegenerative diseases. Researchers in the neurodegenerative disease field are beginning to recognize the possible involvement of Drp1 in causing mitochondrial fragmentation and abnormal mitochondrial dynamics in neurodegenerative diseases. This article summarizes research findings relating Drp1 to mitochondrial fission and fusion, in yeast, worms, and mammals. Based on findings from the Reddy laboratory and others’, we propose that mutant proteins of neurodegenerative diseases, including AD, PD, HD, and ALS, interact with Drp1, activate mitochondrial fission machinery, fragment mitochondria excessively, and impair mitochondrial transport and mitochondrial dynamics, ultimately causing mitochondrial dysfunction and neuronal damage. PMID:21145355

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

Ultrafine particulate matter impairs mitochondrial redox homeostasis and activates phosphatidylinositol 3-kinase mediated DNA damage responses in lymphocytes.

PubMed

Bhargava, Arpit; Tamrakar, Shivani; Aglawe, Aniket; Lad, Harsha; Srivastava, Rupesh Kumar; Mishra, Dinesh Kumar; Tiwari, Rajnarayan; Chaudhury, Koel; Goryacheva, Irina Yu; Mishra, Pradyumna Kumar

2018-03-01

Particulate matter (PM), broadly defined as coarse (2.5-10 μm), fine (0.1-2.5 μm) and ultrafine particles (≤0.1 μm), is a major constituent of ambient air pollution. Recent studies have linked PM exposure (coarse and fine particles) with several human diseases including cancer. However, the molecular mechanisms underlying ultrafine PM exposure induced cellular and sub-cellular repercussions are ill-defined. Since mitochondria are one of the major targets of different environmental pollutants, we herein aimed to understand the molecular repercussion of ultrafine PM exposure on mitochondrial machinery in peripheral blood lymphocytes. Upon comparative analysis, a significantly higher DCF fluorescence was observed in ultrafine PM exposed cells that confirmed the strong pro-oxidant nature of these particles. In addition, the depleted activity of antioxidant enzymes, glutathione reductase and superoxide dismutase suggested the strong association of ultrafine PM with oxidative stress. These results further coincided with mitochondrial membrane depolarization, altered mitochondrial respiratory chain enzyme activity and decline in mtDNA copy number. Moreover, the higher accumulation of DNA damage response proteins (γH2AX, pATM, p-p53), suggested that exposure to ultrafine PM induces DNA damage and triggers phosphatidylinositol 3 kinase mediated response pathway. Further, the alterations in mitochondrial machinery and redox balance among ultrafine PM exposed cells were accompanied by a considerably elevated pro-inflammatory cytokine response. Interestingly, the lower apoptosis levels observed in ultrafine particle treated cells suggest the possibility that the marked alterations may lead to the impairment of mitochondrial-nuclear cross talk. Together, our results showed that ultrafine PM, because of their smaller size possesses significant ability to disturb mitochondrial redox homeostasis and activates phosphatidylinositol 3 kinase mediated DNA damage response

Assembly of the mitochondrial membrane system: mutations in the pho2 locus of the mitochondrial genome of Saccharomyces cerevisiae.

PubMed

Coruzzi, G; Trembath, M K; Tzagoloff, A

1978-12-01

Two mutants of Saccharomyces cerevisiae which show a loss of mitochondrial rutamycin-sensitive ATPase activity are described. Although phenotypically similar to mutants of the mitochondrial locus pho1 [F. Foury and A. Tzagoloff (1976) Eur. J. Biochem. 68, 113-119], these mutants define a second ATPase locus on the mitochondrial DNA (designated pho2), which is genetically unlinked to pho1. Analysis of recombination in crosses involving multiple antibiotic resistance markers indicates that the locus is in the segment of the genome between ery1 and oli2, very close to oli1. In fact it is proposed that the oli1 and pho2 mutations are in the same gene. Supporting evidence for this proposal includes: 1. The analysis of marker retention in petite mutants shows that the oli1 and pho2 loci were either retained or lost together in all cases. 2. Recombination frequencies of 0.05% or less are observed in crosses between the oli1 and pho2 loci. 3. When rho+ revertants are isolated from the pho2 mutants they frequently are oligomycin resistant. 4. pho2 mutants have an altered subunit 9 of the ATPase complex.

Inter- and intraspecific mitochondrial DNA variation in North American bears (Ursus)

USGS Publications Warehouse

Cronin, Matthew A.; Amstrup, Steven C.; Garner, Gerald W.; Vyse, Ernest R.

1991-01-01

We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.

The pathophysiology of mitochondrial disease as modeled in the mouse.

PubMed

Wallace, Douglas C; Fan, Weiwei

2009-08-01

It is now clear that mitochondrial defects are associated with a plethora of clinical phenotypes in man and mouse. This is the result of the mitochondria's central role in energy production, reactive oxygen species (ROS) biology, and apoptosis, and because the mitochondrial genome consists of roughly 1500 genes distributed across the maternal mitochondrial DNA (mtDNA) and the Mendelian nuclear DNA (nDNA). While numerous pathogenic mutations in both mtDNA and nDNA mitochondrial genes have been identified in the past 21 years, the causal role of mitochondrial dysfunction in the common metabolic and degenerative diseases, cancer, and aging is still debated. However, the development of mice harboring mitochondrial gene mutations is permitting demonstration of the direct cause-and-effect relationship between mitochondrial dysfunction and disease. Mutations in nDNA-encoded mitochondrial genes involved in energy metabolism, antioxidant defenses, apoptosis via the mitochondrial permeability transition pore (mtPTP), mitochondrial fusion, and mtDNA biogenesis have already demonstrated the phenotypic importance of mitochondrial defects. These studies are being expanded by the recent development of procedures for introducing mtDNA mutations into the mouse. These studies are providing direct proof that mtDNA mutations are sufficient by themselves to generate major clinical phenotypes. As more different mtDNA types and mtDNA gene mutations are introduced into various mouse nDNA backgrounds, the potential functional role of mtDNA variation in permitting humans and mammals to adapt to different environments and in determining their predisposition to a wide array of diseases should be definitively demonstrated.

Transoceanic Dispersal and Plate Tectonics Shaped Global Cockroach Distributions: Evidence from Mitochondrial Phylogenomics.

PubMed

Bourguignon, Thomas; Tang, Qian; Ho, Simon Y W; Juna, Frantisek; Wang, Zongqing; Arab, Daej A; Cameron, Stephen L; Walker, James; Rentz, David; Evans, Theodore A; Lo, Nathan

2018-04-01

Following the acceptance of plate tectonics theory in the latter half of the 20th century, vicariance became the dominant explanation for the distributions of many plant and animal groups. In recent years, however, molecular-clock analyses have challenged a number of well-accepted hypotheses of vicariance. As a widespread group of insects with a fossil record dating back 300 My, cockroaches provide an ideal model for testing hypotheses of vicariance through plate tectonics versus transoceanic dispersal. However, their evolutionary history remains poorly understood, in part due to unresolved relationships among the nine recognized families. Here, we present a phylogenetic estimate of all extant cockroach families, as well as a timescale for their evolution, based on the complete mitochondrial genomes of 119 cockroach species. Divergence dating analyses indicated that the last common ancestor of all extant cockroaches appeared ∼235 Ma, ∼95 My prior to the appearance of fossils that can be assigned to extant families, and before the breakup of Pangaea began. We reconstructed the geographic ranges of ancestral cockroaches and found tentative support for vicariance through plate tectonics within and between several major lineages. We also found evidence of transoceanic dispersal in lineages found across the Australian, Indo-Malayan, African, and Madagascan regions. Our analyses provide evidence that both vicariance and dispersal have played important roles in shaping the distribution and diversity of these insects.

SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake.

PubMed

Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

2017-05-01

Mitochondrial calcium ([Ca 2+ ] m ) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca 2+ ] m uptake upon SK channel activation as detected by time lapse mitochondrial Ca 2+ measurements with the Ca 2+ -binding mitochondria-targeted aequorin and FRET-based [Ca 2+ ] m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca 2+ ] m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death.

SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake

PubMed Central

Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

2017-01-01

Mitochondrial calcium ([Ca2+]m) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca2+]m uptake upon SK channel activation as detected by time lapse mitochondrial Ca2+ measurements with the Ca2+-binding mitochondria-targeted aequorin and FRET-based [Ca2+]m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca2+]m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death. PMID:28282037

Mitochondrial health, the epigenome and healthspan

PubMed Central

Aon, Miguel A.; Cortassa, Sonia; Juhaszova, Magdalena; Sollott, Steven J.

2016-01-01

Food nutrients and metabolic supply-demand dynamics constitute environmental factors that interact with our genome influencing health and disease states. These gene–environment interactions converge at the metabolic-epigenome-genome axis to regulate gene expression and phenotypic outcomes. Mounting evidence indicates that nutrients and lifestyle strongly influence genome-metabolic functional interactions determining disease via altered epigenetic regulation. The mitochondrial network is a central player of the metabolic-epigenome-genome axis, regulating the level of key metabolites (NAD+, AcCoA, ATP) acting as substrates/cofactors for acetyl transferases, kinases (e.g., protein kinase A), deacetylases (e.g., sirtuins). The chromatin, an assembly of DNA and nucleoproteins, regulates the transcriptional process, acting at the epigenomic interface between metabolism and the genome. Within this framework, we review existing evidence showing that preservation of mitochondrial network function is directly involved in decreasing the rate of damage accumulation thus slowing aging and improving healthspan. PMID:27358026

Mitochondrial peptides modulate mitochondrial function during cellular senescence.

PubMed

Kim, Su-Jeong; Mehta, Hemal H; Wan, Junxiang; Kuehnemann, Chisaka; Chen, Jingcheng; Hu, Ji-Fan; Hoffman, Andrew R; Cohen, Pinchas

2018-06-10

Cellular senescence is a complex cell fate response that is thought to underlie several age-related pathologies. Despite a loss of proliferative potential, senescent cells are metabolically active and produce energy-consuming effectors, including senescence-associated secretory phenotypes (SASPs). Mitochondria play crucial roles in energy production and cellular signaling, but the key features of mitochondrial physiology and particularly of mitochondria-derived peptides (MDPs), remain underexplored in senescence responses. Here, we used primary human fibroblasts made senescent by replicative exhaustion, doxorubicin or hydrogen peroxide treatment, and examined the number of mitochondria and the levels of mitochondrial respiration, mitochondrial DNA methylation and the mitochondria-encoded peptides humanin, MOTS-c, SHLP2 and SHLP6. Senescent cells showed increased numbers of mitochondria and higher levels of mitochondrial respiration, variable changes in mitochondrial DNA methylation, and elevated levels of humanin and MOTS-c. Humanin and MOTS-c administration modestly increased mitochondrial respiration and selected components of the SASP in doxorubicin-induced senescent cells partially via JAK pathway. Targeting metabolism in senescence cells is an important strategy to reduce SASP production for eliminating the deleterious effects of senescence. These results provide insight into the role of MDPs in mitochondrial energetics and the production of SASP components by senescent cells.

Garlic activates SIRT-3 to prevent cardiac oxidative stress and mitochondrial dysfunction in diabetes.

PubMed

Sultana, Md Razia; Bagul, Pankaj K; Katare, Parameshwar B; Anwar Mohammed, Soheb; Padiya, Raju; Banerjee, Sanjay K

2016-11-01

Cardiac complications are major contributor in the mortality of diabetic people. Mitochondrial dysfunctioning is a crucial contributor for the cardiac complications in diabetes, and SIRT-3 remains the major mitochondrial deacetylase. We hypothesized whether garlic has any role on SIRT-3 to prevent mitochondrial dysfunction in diabetic heart. Rats with developed hyperglycemia after STZ injection were divided into two groups; diabetic (Dia) and diabetic+garlic (Dia+Garl). Garlic was administered at a dose of 250mg/kg/day, orally for four weeks. An additional group was maintained to evaluate the effect of raw garlic administration on control rat heart. We have observed altered functioning of cardiac mitochondrial enzymes involved in metabolic pathways, and increased levels of cardiac ROS with decreased activity of catalase and SOD in diabetic rats. Cardiac mRNA expression of TFAM, PGC-1α, and CO1 was also altered in diabetes. In addition, reduced levels of electron transport chain complexes that observed in Dia group were normalized with garlic administration. This indicates the presence of increased oxidative stress with mitochondrial dysfunctioning in diabetic heart. We have observed reduced activity of SIRT3 and increased acetylation of MnSOD. Silencing SIRT-3 in cells also revealed the same. However, administration of garlic improved the SIRT-3 and MnSOD activity, by deacetylating MnSOD. Increased SOD activity was correlated with reduced levels of ROS in garlic-administered rat hearts. Collectively, our results provide an insight into garlic's protection to T1DM heart through activation of SIRT3-MnSOD pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

[Distribution of a deletion-insertion polymorphism in intergenic region V of mitochondrial DNA among the aboriginal population of Tuva].

PubMed

Golubenko, M V; Puzyrev, V P; Saliukov, V B; Kucher, A N; Sanchat, N O

2000-03-01

Mitochondrial DNA region V deletion-insertion polymorphism was examined in three Tuvinian populations inhabiting western, northeastern, and southeastern parts of the republic. The 9-bp deletion was characterized by nonrandom distribution across the Tuva territory: its frequency in the western population (13.37%) was statistically significantly higher than that in the northeastern (4.62%), and southeastern populations, as well as in Mongols, who are territorially and ethnically close to Tuvinians. The insertion mutation in the region V was detected with a frequency of about 3% in two out of the three populations tested.

Potential role of licofelone, minocycline and their combination against chronic fatigue stress induced behavioral, biochemical and mitochondrial alterations in mice.

PubMed

Kumar, Anil; Vashist, Aditi; Kumar, Puneet; Kalonia, Harikesh; Mishra, Jitendriya

2012-01-01

Chronic fatigue stress (CFS) is a common complaint among general population. Persistent and debilitating fatigue severely impairs daily functioning and is usually accompanied by combination of several physical and psychiatric problems. It is now well established fact that oxidative stress and neuroinflammation are involved in the pathophysiology of chronic fatigue and related disorders. Targeting both COX (cyclooxygenase) and 5-LOX (lipoxygenase) pathways have been proposed to be involved in neuroprotective effect. In the present study, mice were put on the running wheel apparatus for 6 min test session daily for 21 days, what produced fatigue like condition. The locomotor activity and anxiety like behavior were measured on 0, 8(th), 15(th) and 22(nd) day. The brains were isolated on 22(nd) day immediately after the behavioral assessments for the estimation of oxidative stress parameters and mitochondrial enzyme complexes activity. Pre-treatment with licofelone (2.5, 5 and 10 mg/kg, po) and minocycline (50 and 100 mg/kg, po) for 21 days, significantly attenuated fatigue like behavior as compared to the control (rotating wheel activity test session, RWATS) group. Further, licofelone (5 and 10 mg/kg, po) and minocycline (50 and 100 mg/kg, po) drug treatments for 21 days significantly attenuated behavioral alterations, oxidative damage and restored mitochondrial enzyme complex activities (I, II, III and IV) as compared to control, whereas combination of licofelone (5 mg/kg) with minocycline (50 mg/kg) significantly potentiated their protective effect which was significant as compared to their effect per se. The present study highlights the therapeutic potential of licofelone, minocycline and their combination against CFS in mice.

Diabetes-Induced Decrease in Renal Oxygen Tension: Effects of an Altered Metabolism

NASA Astrophysics Data System (ADS)

Palm, Fredrik; Carlsson, Per-Ola; Fasching, Angelica; Hansell, Peter; Liss, Per

During conditions with experimental diabetes mellitus, it is evident that several alterations in renal oxygen metabolism occur, including increased mitochondrial respiration and increased lactate accumulation in the renal tissue. Consequently, these alterations will contribute to decrease the interstitial pO2, preferentially in the renal medulla of animals with sustained long-term hyperglycemia.

Dynamic intervention: pathogen disarmament of mitochondrial-based immune surveillance.

PubMed

Holland, Robin L; Blanke, Steven R

2014-11-12

In this issue of Cell Host & Microbe, Suzuki et al. (2014) describe a Vibrio cholerae Type-III-secreted effector that targets mitochondrial dynamics to dampen host innate immune signaling. This suggests that mammalian hosts possess surveillance mechanisms to monitor pathogen-mediated alterations in the integrity of normal cellular processes and organelles. Copyright © 2014 Elsevier Inc. All rights reserved.

Alterations in intrinsic mitochondrial function with aging are fiber type-specific and do not explain differential atrophy between muscles.

PubMed

Picard, Martin; Ritchie, Darmyn; Thomas, Melissa M; Wright, Kathryn J; Hepple, Russell T

2011-12-01

To determine whether mitochondrial dysfunction is causally related to muscle atrophy with aging, we examined respiratory capacity, H(2) O(2) emission, and function of the mitochondrial permeability transition pore (mPTP) in permeabilized myofibers prepared from four rat muscles that span a range of fiber type and degree of age-related atrophy. Muscle atrophy with aging was greatest in fast-twitch gastrocnemius (Gas) muscle (-38%), intermediate in both the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (Sol) muscles (-21%), and non-existent in adductor longus (AL) muscle (+47%). In contrast, indices of mitochondrial dysfunction did not correspond to this differential degree of atrophy. Specifically, despite higher protein expression for oxidative phosphorylation (oxphos) system in fast Gas and EDL, state III respiratory capacity per myofiber wet weight was unchanged with aging, whereas the slow Sol showed proportional decreases in oxphos protein, citrate synthase activity, and state III respiration. Free radical leak (H(2) O(2) emission per O(2) flux) under state III respiration was higher with aging in the fast Gas, whereas state II free radical leak was higher in the slow AL. Only the fast muscles had impaired mPTP function with aging, with lower mitochondrial calcium retention capacity in EDL and shorter time to mPTP opening in Gas and EDL. Collectively, our results underscore that the age-related changes in muscle mitochondrial function depend largely upon fiber type and are unrelated to the severity of muscle atrophy, suggesting that intrinsic changes in mitochondrial function are unlikely to be causally involved in aging muscle atrophy. © 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

Doxycycline protects against ROS-induced mitochondrial fragmentation and ISO-induced heart failure

PubMed Central

Riba, Adam; Deres, Laszlo; Eros, Krisztian; Szabo, Aliz; Magyar, Klara; Sumegi, Balazs; Toth, Kalman; Halmosi, Robert; Szabados, Eszter

2017-01-01

In addition to their anti-bacterial action, tetracyclines also have complex biological effects, including the modification of mitochondrial protein synthesis, metabolism and gene-expression. Long-term clinical studies have been performed using tetracyclines, without significant side effects. Previous studies demonstrated that doxycycline (DOX), a major tetracyclin antibiotic, exerted a protective effect in animal models of heart failure; however, its exact molecular mechanism is still unknown. Here, we provide the first evidence that DOX reduces oxidative stress—induced mitochondrial fragmentation and depolarization in H9c2 cardiomyocytes and beneficially alters the expression of Mfn-2, OPA-1 and Drp-1 –the main regulators of mitochondrial fusion and fission—in our isoproterenol (ISO)–induced heart failure model, ultimately decreasing the severity of heart failure. In mitochondria, oxidative stress causes a shift toward fission which leads to mitochondrial fragmentation and cell death. Protecting mitochondria from oxidative stress, and the regulation of mitochondrial dynamics by drugs that shift the balance toward fusion, could be a novel therapeutic approach for heart failure. On the basis of our findings, we raise the possibility that DOX could be a novel therapeutic agent in the future treatment of heart failure. PMID:28384228

Transcriptome-wide analyses indicate mitochondrial responses to particulate air pollution exposure.

PubMed

Winckelmans, Ellen; Nawrot, Tim S; Tsamou, Maria; Den Hond, Elly; Baeyens, Willy; Kleinjans, Jos; Lefebvre, Wouter; Van Larebeke, Nicolas; Peusens, Martien; Plusquin, Michelle; Reynders, Hans; Schoeters, Greet; Vanpoucke, Charlotte; de Kok, Theo M; Vrijens, Karen

2017-08-18

Due to their lack of repair capacity mitochondria are critical targets for environmental toxicants. We studied genes and pathways reflecting mitochondrial responses to short- and medium-term PM 10 exposure. Whole genome gene expression was measured in peripheral blood of 98 adults (49% women). We performed linear regression analyses stratified by sex and adjusted for individual and temporal characteristics to investigate alterations in gene expression induced by short-term (week before blood sampling) and medium-term (month before blood sampling) PM 10 exposure. Overrepresentation analyses (ConsensusPathDB) were performed to identify enriched mitochondrial associated pathways and gene ontology sets. Thirteen Human MitoCarta genes were measured by means of quantitative real-time polymerase chain reaction (qPCR) along with mitochondrial DNA (mtDNA) content in an independent validation cohort (n = 169, 55.6% women). Overrepresentation analyses revealed significant pathways (p-value <0.05) related to mitochondrial genome maintenance and apoptosis for short-term exposure and to the electron transport chain (ETC) for medium-term exposure in women. For men, medium-term PM 10 exposure was associated with the Tri Carbonic Acid cycle. In an independent study population, we validated several ETC genes, including UQCRH and COX7C (q-value <0.05), and some genes crucial for the maintenance of the mitochondrial genome, including LONP1 (q-value: 0.07) and POLG (q-value: 0.04) in women. In this exploratory study, we identified mitochondrial genes and pathways associated with particulate air pollution indicating upregulation of energy producing pathways as a potential mechanism to compensate for PM-induced mitochondrial damage.

Mitochondrial-nuclear genome interactions in nonalcoholic fatty liver disease in mice

PubMed Central

Betancourt, Angela M.; King, Adrienne L.; Fetterman, Jessica L.; Millender-Swain, Telisha; Finley, Rachel D.; Oliva, Claudia R.; Crowe, David Ralph; Ballinger, Scott W.; Bailey, Shannon M.

2014-01-01

Nonalcoholic fatty liver disease (NAFLD) involves significant changes in liver metabolism characterized by oxidative stress, lipid accumulation, and fibrogenesis. Mitochondrial dysfunction and bioenergetic defects also contribute to NAFLD. Herein, we examined whether differences in mtDNA influence NAFLD. To determine the role of mitochondrial and nuclear genomes in NAFLD, Mitochondrial-Nuclear eXchange (MNX) mice were fed an atherogenic diet. MNX mice have mtDNA from C57BL/6J mice on a C3H/HeN nuclear background and vice versa. Results from MNX mice were compared to wild-type C57BL/6J and C3H/HeN mice fed a control or atherogenic diet. Mice with the C57BL/6J nuclear genome developed more macrosteatosis, inflammation, and fibrosis compared with mice containing the C3H/HeN nuclear genome when fed the atherogenic diet. These changes were associated with parallel alterations in inflammation and fibrosis gene expression in wild-type mice, with intermediate responses in MNX mice. Mice with the C57BL/6J nuclear genome had increased State 4 respiration, whereas MNX mice had decreased State 3 respiration and RCR when fed the atherogenic diet. Complex IV activity and most mitochondrial biogenesis genes were increased in mice with the C57BL/6J nuclear or mitochondrial genome, or both fed the atherogenic diet. These results reveal new interactions between mitochondrial and nuclear genomes and support the concept that mtDNA influences mitochondrial function and metabolic pathways implicated in NAFLD. PMID:24758559

Synergy in free radical generation is blunted by high-fat diet induced alterations in skeletal muscle mitochondrial metabolism.

PubMed

Li, Yanjun; Periwal, Vipul

2013-03-05

Due to their role in cellular energetics and metabolism, skeletal muscle mitochondria appear to play a key role in the development of insulin resistance and type II diabetes. High-fat diet can induce higher levels of reactive oxygen species (ROS), evidenced by hydrogen peroxide (H2O2) emission from mitochondria, which may be causal for insulin resistance in skeletal muscle. The underlying mechanisms are unclear. Recent published data on single substrate (pyruvate, succinate, fat) metabolism in both normal diet (CON) and high-fat diet (HFD) states of skeletal muscle allowed us to develop an integrated mathematical model of skeletal muscle mitochondrial metabolism. Model simulations suggested that long-term HFD may affect specific metabolic reaction/pathways by altering enzyme activities. Our model allows us to predict oxygen consumption and ROS generation for any combination of substrates. In particular, we predict a synergy between (iso-membrane potential) combinations of pyruvate and fat in ROS production compared to the sum of ROS production with each substrate singly in both CON and HFD states. This synergy is blunted in the HFD state. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Changes in mitochondrial respiration in the human placenta over gestation.

PubMed

Holland, Olivia J; Hickey, Anthony J R; Alvsaker, Anna; Moran, Stephanie; Hedges, Christopher; Chamley, Lawrence W; Perkins, Anthony V

2017-09-01

Placental mitochondria are subjected to micro-environmental changes throughout gestation, in particular large variations in oxygen. How placental mitochondrial respiration adapts to changing oxygen concentrations remains unexplored. Additionally, placental tissue is often studied in culture; however, the effect of culture on placental mitochondria is unclear. Placental tissue was obtained from first trimester and term (laboured and non-laboured) pregnancies, and selectively permeabilized to access mitochondria. Respirometry was used to compare respiration states and substrate use in mitochondria. Additionally, explants of placental tissue were cultured for four, 12, 24, 48, or 96 h and respiration measured. Mitochondrial respiration decreased at 11 weeks compared to earlier gestations (p = 0.05-0.001), and mitochondrial content increased at 12-13 weeks compared to 7-10 weeks (p = 0.042). In term placentae, oxidative phosphorylation (OXPHOS) through mitochondrial complex IV (p < 0.001), the relative proportion of OXPHOS CI (p < 0.001), the total capacity of the respiratory system (p = 0.003), and mitochondrial content (p < 0.001) were higher compared to first trimester. Respiration was increased (p ≤ 0.006-0.001) in laboured compared to non-laboured placenta. After four hours of culture, respiration was depressed compared to fresh tissue from the same placenta and continued to decline with time in culture. Markers of apoptosis were increased, while markers of autophagy, mitochondrial biogenesis, and mitochondrial membrane potential were decreased after four hours of culture. Respiration and mitochondrial content alter over gestation/with labour. Decreased respiration at 11 weeks and increased mitochondrial content at 12-13 weeks may relate to onset of maternal blood flow, and increased respiration as a result of labour may be an adaptation to ischaemia-reperfusion. At term, mitochondria were more susceptible to changes in respiratory function

Mitochondrial flash as a novel biomarker of mitochondrial respiration in the heart.

PubMed

Gong, Guohua; Liu, Xiaoyun; Zhang, Huiliang; Sheu, Shey-Shing; Wang, Wang

2015-10-01

Mitochondrial respiration through electron transport chain (ETC) activity generates ATP and reactive oxygen species in eukaryotic cells. The modulation of mitochondrial respiration in vivo or under physiological conditions remains elusive largely due to the lack of appropriate approach to monitor ETC activity in a real-time manner. Here, we show that ETC-coupled mitochondrial flash is a novel biomarker for monitoring mitochondrial respiration under pathophysiological conditions in cultured adult cardiac myocyte and perfused beating heart. Through real-time confocal imaging, we follow the frequency of a transient bursting fluorescent signal, named mitochondrial flash, from individual mitochondria within intact cells expressing a mitochondrial matrix-targeted probe, mt-cpYFP (mitochondrial-circularly permuted yellow fluorescent protein). This mt-cpYFP recorded mitochondrial flash has been shown to be composed of a major superoxide signal with a minor alkalization signal within the mitochondrial matrix. Through manipulating physiological substrates for mitochondrial respiration, we find a close coupling between flash frequency and the ETC electron flow, as measured by oxygen consumption rate in cardiac myocyte. Stimulating electron flow under physiological conditions increases flash frequency. On the other hand, partially block or slowdown electron flow by inhibiting the F0F1 ATPase, which represents a pathological condition, transiently increases then decreases flash frequency. Limiting electron entrance at complex I by knocking out Ndufs4, an assembling subunit of complex I, suppresses mitochondrial flash activity. These results suggest that mitochondrial electron flow can be monitored by real-time imaging of mitochondrial flash. The mitochondrial flash frequency could be used as a novel biomarker for mitochondrial respiration under physiological and pathological conditions. Copyright © 2015 the American Physiological Society.

Melatonin: A Mitochondrial Targeting Molecule Involving Mitochondrial Protection and Dynamics

PubMed Central

Tan, Dun-Xian; Manchester, Lucien C.; Qin, Lilan; Reiter, Russel J.

2016-01-01

Melatonin has been speculated to be mainly synthesized by mitochondria. This speculation is supported by the recent discovery that aralkylamine N-acetyltransferase/serotonin N-acetyltransferase (AANAT/SNAT) is localized in mitochondria of oocytes and the isolated mitochondria generate melatonin. We have also speculated that melatonin is a mitochondria-targeted antioxidant. It accumulates in mitochondria with high concentration against a concentration gradient. This is probably achieved by an active transportation via mitochondrial melatonin transporter(s). Melatonin protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting the mitochondrial permeability transition pore (MPTP), and activating uncoupling proteins (UCPs). Thus, melatonin maintains the optimal mitochondrial membrane potential and preserves mitochondrial functions. In addition, mitochondrial biogenesis and dynamics is also regulated by melatonin. In most cases, melatonin reduces mitochondrial fission and elevates their fusion. Mitochondrial dynamics exhibit an oscillatory pattern which matches the melatonin circadian secretory rhythm in pinealeocytes and probably in other cells. Recently, melatonin has been found to promote mitophagy and improve homeostasis of mitochondria. PMID:27999288

Mitochondria-associated endoplasmic reticulum membranes allow adaptation of mitochondrial metabolism to glucose availability in the liver.

PubMed

Theurey, Pierre; Tubbs, Emily; Vial, Guillaume; Jacquemetton, Julien; Bendridi, Nadia; Chauvin, Marie-Agnès; Alam, Muhammad Rizwan; Le Romancer, Muriel; Vidal, Hubert; Rieusset, Jennifer

2016-04-01

Mitochondria-associated endoplasmic reticulum membranes (MAM) play a key role in mitochondrial dynamics and function and in hepatic insulin action. Whereas mitochondria are important regulators of energy metabolism, the nutritional regulation of MAM in the liver and its role in the adaptation of mitochondria physiology to nutrient availability are unknown. In this study, we found that the fasted to postprandial transition reduced the number of endoplasmic reticulum-mitochondria contact points in mouse liver. Screening of potential hormonal/metabolic signals revealed glucose as the main nutritional regulator of hepatic MAM integrity both in vitro and in vivo Glucose reduced organelle interactions through the pentose phosphate-protein phosphatase 2A (PP-PP2A) pathway, induced mitochondria fission, and impaired respiration. Blocking MAM reduction counteracted glucose-induced mitochondrial alterations. Furthermore, disruption of MAM integrity mimicked effects of glucose on mitochondria dynamics and function. This glucose-sensing system is deficient in the liver of insulin-resistant ob/ob and cyclophilin D-KO mice, both characterized by chronic disruption of MAM integrity, mitochondrial fission, and altered mitochondrial respiration. These data indicate that MAM contribute to the hepatic glucose-sensing system, allowing regulation of mitochondria dynamics and function during nutritional transition. Chronic disruption of MAM may participate in hepatic mitochondrial dysfunction associated with insulin resistance. © The Author (2016). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. All rights reserved.

Inhibiting Mitochondrial DNA Ligase IIIα Activates Caspase 1-Dependent Apoptosis in Cancer Cells.

PubMed

Sallmyr, Annahita; Matsumoto, Yoshihiro; Roginskaya, Vera; Van Houten, Bennett; Tomkinson, Alan E

2016-09-15

Elevated levels of DNA ligase IIIα (LigIIIα) have been identified as a biomarker of an alteration in DNA repair in cancer cells that confers hypersensitivity to a LigIIIα inhibitor, L67, in combination with a poly (ADP-ribose) polymerase inhibitor. Because LigIIIα functions in the nucleus and mitochondria, we examined the effect of L67 on these organelles. Here, we show that, although the DNA ligase inhibitor selectively targets mitochondria, cancer and nonmalignant cells respond differently to disruption of mitochondrial DNA metabolism. Inhibition of mitochondrial LigIIIα in cancer cells resulted in abnormal mitochondrial morphology, reduced levels of mitochondrial DNA, and increased levels of mitochondrially generated reactive oxygen species that caused nuclear DNA damage. In contrast, these effects did not occur in nonmalignant cells. Furthermore, inhibition of mitochondrial LigIIIα activated a caspase 1-dependent apoptotic pathway, which is known to be part of inflammatory responses induced by pathogenic microorganisms in cancer, but not nonmalignant cells. These results demonstrate that the disruption of mitochondrial DNA metabolism elicits different responses in nonmalignant and cancer cells and suggests that the abnormal response in cancer cells may be exploited in the development of novel therapeutic strategies that selectively target cancer cells. Cancer Res; 76(18); 5431-41. ©2016 AACR. ©2016 American Association for Cancer Research.

Mitochondrial threshold effects.

PubMed Central

Rossignol, Rodrigue; Faustin, Benjamin; Rocher, Christophe; Malgat, Monique; Mazat, Jean-Pierre; Letellier, Thierry

2003-01-01

The study of mitochondrial diseases has revealed dramatic variability in the phenotypic presentation of mitochondrial genetic defects. To attempt to understand this variability, different authors have studied energy metabolism in transmitochondrial cell lines carrying different proportions of various pathogenic mutations in their mitochondrial DNA. The same kinds of experiments have been performed on isolated mitochondria and on tissue biopsies taken from patients with mitochondrial diseases. The results have shown that, in most cases, phenotypic manifestation of the genetic defect occurs only when a threshold level is exceeded, and this phenomenon has been named the 'phenotypic threshold effect'. Subsequently, several authors showed that it was possible to inhibit considerably the activity of a respiratory chain complex, up to a critical value, without affecting the rate of mitochondrial respiration or ATP synthesis. This phenomenon was called the 'biochemical threshold effect'. More recently, quantitative analysis of the effects of various mutations in mitochondrial DNA on the rate of mitochondrial protein synthesis has revealed the existence of a 'translational threshold effect'. In this review these different mitochondrial threshold effects are discussed, along with their molecular bases and the roles that they play in the presentation of mitochondrial diseases. PMID:12467494

Time-controlled fasting prevents aging-like mitochondrial changes induced by persistent dietary fat overload in skeletal muscle

PubMed Central

Lettieri-Barbato, Daniele; Cannata, Stefano Maria; Casagrande, Viviana; Ciriolo, Maria Rosa

2018-01-01

A large body of evidence suggests that persistent dietary fat overload causes mitochondrial dysfunction and systemic metabolic gridlock. Mitochondrial and lipid metabolism in skeletal muscle (SkM) are severely affected upon persistent high fat diet (HFD) leading to premature tissue aging. Here, we designed weekly cycles of fasting (called as time-controlled fasting, TCF) and showed that they were effective in limiting mitochondrial damage and metabolic disturbances induced by HFD. Specifically, TCF was able to prevent the decline of adipose triglyceride lipase (Atgl), maintain efficient mitochondrial respiration in SkM as well as improve blood glucose and lipid profile. Atgl was found to be the mediator of such preventive effects as its downregulation or up-regulation in C2C12 myotubes triggers mitochondrial alteration or protects against the deleterious effects of high fat levels respectively. In conclusion, TCF could represent an effective strategy to limit mitochondrial impairment and metabolic inflexibility that are typically induced by modern western diets or during aging. PMID:29742122

Time-controlled fasting prevents aging-like mitochondrial changes induced by persistent dietary fat overload in skeletal muscle.

PubMed

Lettieri-Barbato, Daniele; Cannata, Stefano Maria; Casagrande, Viviana; Ciriolo, Maria Rosa; Aquilano, Katia

2018-01-01

A large body of evidence suggests that persistent dietary fat overload causes mitochondrial dysfunction and systemic metabolic gridlock. Mitochondrial and lipid metabolism in skeletal muscle (SkM) are severely affected upon persistent high fat diet (HFD) leading to premature tissue aging. Here, we designed weekly cycles of fasting (called as time-controlled fasting, TCF) and showed that they were effective in limiting mitochondrial damage and metabolic disturbances induced by HFD. Specifically, TCF was able to prevent the decline of adipose triglyceride lipase (Atgl), maintain efficient mitochondrial respiration in SkM as well as improve blood glucose and lipid profile. Atgl was found to be the mediator of such preventive effects as its downregulation or up-regulation in C2C12 myotubes triggers mitochondrial alteration or protects against the deleterious effects of high fat levels respectively. In conclusion, TCF could represent an effective strategy to limit mitochondrial impairment and metabolic inflexibility that are typically induced by modern western diets or during aging.

Obesity in mares promotes uterine inflammation and alters embryo lipid fingerprints and homeostasis.

PubMed

Sessions-Bresnahan, Dawn R; Heuberger, Adam L; Carnevale, Elaine M

2018-05-07

Maternal body composition can be an important determinant for development of obesity and metabolic syndrome in adult offspring. Obesity-related outcomes in offspring may include epigenetic alterations; however, mechanisms of fetal programming remain to be fully elucidated. This study was conducted to determine the impact of maternal obesity in the absence of a high fat diet on equine endometrium and preimplantation embryos. Embryos were collected from normal and obese mares at 8 and 16 d and a uterine biopsy at 16 d (0 d = ovulation). With the exception of 8 d embryos, each sample was divided into two pieces. One piece was analyzed for gene expression markers related to carbohydrate metabolism, lipid homeostasis, inflammation, endoplasmic reticulum stress, oxidative stress, mitochondrial stress, and components of the insulin-like growth factor (IGF) system. The second piece was analyzed for lipid content using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Obese mares had elevated concentrations of insulin, leptin and total cholesterol, and they tended to have increased triglycerides and decreased insulin sensitivity. Embryos from obese mares had altered transcript abundance in genes for inflammation and lipid homeostasis, as well as, endoplasmic reticulum, oxidative and mitochondrial stress and altered lipid fingerprints. Endometrium from obese mares had increased expression of inflammatory cytokines, lipid homeostasis regulation, mitochondrial stress, and the IGF2 system. This study demonstrates increased adiposity in mares alters the uterine environment, transcript abundance of genes for cellular functions, and lipid profiles of embryos. These alterations could affect prenatal programming, with potential long-term effects in offspring.

Progesterone induces neuroprotection following reperfusion-promoted mitochondrial dysfunction after focal cerebral ischemia in rats.

PubMed

Andrabi, Syed Suhail; Parvez, Suhel; Tabassum, Heena

2017-06-01

Organelle damage and increases in mitochondrial permeabilization are key events in the development of cerebral ischemic tissue injury because they cause both modifications in ATP turnover and cellular apoptosis/necrosis. Early restoration of blood flow and improvement of mitochondrial function might reverse the situation and help in recovery following an onset of stroke. Mitochondria and related bioenergetic processes can be effectively used as pharmacological targets. Progesterone (P4), one of the promising neurosteroids, has been found to be neuroprotective in various models of neurological diseases, through a number of mechanisms. This influenced us to investigate the possible role of P4 in the mitochondria-mediated neuroprotective mechanism in an ischemic stroke model of rat. In this study, we have shown the positive effect of P4 administration on behavioral deficits and mitochondrial health in an ischemic stroke injury model of transient middle cerebral artery occlusion (tMCAO). After induction of tMCAO, the rats received an initial intraperitoneal injection of P4 (8 mg/kg body weight) or vehicle at 1 h post-occlusion followed by subcutaneous injections at 6, 12 and 18 h. Behavioral assessment for functional deficits included grip strength, motor coordination and gait analysis. Findings revealed a significant improvement with P4 treatment in tMCAO animals. Staining of isolated brain slices from P4-treated rats with 2,3,5-triphenyltetrazolium chloride (TTC) showed a reduction in the infarct area in comparison to the vehicle group, indicating the presence of an increased number of viable mitochondria. P4 treatment was also able to attenuate mitochondrial reactive oxygen species (ROS) production, as well as block the mitochondrial permeability transition pore (mPTP), in the tMCAO injury model. In addition, it was also able to ameliorate the altered mitochondrial membrane potential and respiration ratio in the ischemic animals, thereby suggesting that P4 has

Mitochondrial DNA Variant in COX1 Subunit Significantly Alters Energy Metabolism of Geographically Divergent Wild Isolates in Caenorhabditis elegans

PubMed Central

Dingley, Stephen D.; Polyak, Erzsebet; Ostrovsky, Julian; Srinivasan, Satish; Lee, Icksoo; Rosenfeld, Amy B.; Tsukikawa, Mai; Xiao, Rui; Selak, Mary A.; Coon, Joshua J.; Hebert, Alexander S.; Grimsrud, Paul A.; Kwon, Young Joon; Pagliarini, David J.; Gai, Xiaowu; Schurr, Theodore G.; Hüttemann, Maik; Nakamaru-Ogiso, Eiko; Falk, Marni J.

2014-01-01

Mitochondrial DNA (mtDNA) sequence variation can influence the penetrance of complex diseases and climatic adaptation. While studies in geographically defined human populations suggest that mtDNA mutations become fixed when they have conferred metabolic capabilities optimally suited for a specific environment, it has been challenging to definitively assign adaptive functions to specific mtDNA sequence variants in mammals. We investigated whether mtDNA genome variation functionally influences Caenorhabditis elegans wild isolates of distinct mtDNA lineages and geographic origins. We found that, relative to N2 (England) wild-type nematodes, CB4856 wild isolates from a warmer native climate (Hawaii) had a unique p.A12S amino acid substitution in the mtDNA-encoded COX1 core catalytic subunit of mitochondrial complex IV (CIV). Relative to N2, CB4856 worms grown at 20 °C had significantly increased CIV enzyme activity, mitochondrial matrix oxidant burden, and sensitivity to oxidative stress but had significantly reduced lifespan and mitochondrial membrane potential. Interestingly, mitochondrial membrane potential was significantly increased in CB4856 grown at its native temperature of 25 °C. A transmitochondrial cybrid worm strain, chpIR (M, CB4856 > N2), was bred as homoplasmic for the CB4856 mtDNA genome in the N2 nuclear background. The cybrid strain also displayed significantly increased CIV activity, demonstrating that this difference results from the mtDNA-encoded p.A12S variant. However, chpIR (M, CB4856 > N2) worms had significantly reduced median and maximal lifespan relative to CB4856, which may relate to their nuclear– mtDNA genome mismatch. Overall, these data suggest that C. elegans wild isolates of varying geographic origins may adapt to environmental challenges through mtDNA variation to modulate critical aspects of mitochondrial energy metabolism. PMID:24534730

Nucleus accumbens deep-brain stimulation efficacy in ACTH-pretreated rats: alterations in mitochondrial function relate to antidepressant-like effects

PubMed Central

Kim, Y; McGee, S; Czeczor, J K; Walker, A J; Kale, R P; Kouzani, A Z; Walder, K; Berk, M; Tye, S J

2016-01-01

Mitochondrial dysfunction has a critical role in the pathophysiology of mood disorders and treatment response. To investigate this, we established an animal model exhibiting a state of antidepressant treatment resistance in male Wistar rats using 21 days of adrenocorticotropic hormone (ACTH) administration (100 μg per day). First, the effect of ACTH treatment on the efficacy of imipramine (10 mg kg−1) was investigated alongside its effect on the prefrontal cortex (PFC) mitochondrial function. Second, we examined the mood-regulatory actions of chronic (7 day) high-frequency nucleus accumbens (NAc) deep-brain stimulation (DBS; 130 Hz, 100 μA, 90 μS) and concomitant PFC mitochondrial function. Antidepressant-like responses were assessed in the open field test (OFT) and forced swim test (FST) for both conditions. ACTH pretreatment prevented imipramine-mediated improvement in mobility during the FST (P<0.05). NAc DBS effectively improved FST mobility in ACTH-treated animals (P<0.05). No improvement in mobility was observed for sham control animals (P>0.05). Analyses of PFC mitochondrial function revealed that ACTH-treated animals had decreased capacity for adenosine triphosphate production compared with controls. In contrast, ACTH animals following NAc DBS demonstrated greater mitochondrial function relative to controls. Interestingly, a proportion (30%) of the ACTH-treated animals exhibited heightened locomotor activity in the OFT and exaggerated escape behaviors during the FST, together with general hyperactivity in their home-cage settings. More importantly, the induction of this mania-like phenotype was accompanied by overcompensative increased mitochondrial respiration. Manifestation of a DBS-induced mania-like phenotype in imipramine-resistant animals highlights the potential use of this model in elucidating mechanisms of mood dysregulation. PMID:27327257

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