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.

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

PubMed Central

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

2011-01-01

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

GPER mediates the effects of 17β-estradiol in cardiac mitochondrial biogenesis and function.

PubMed

Sbert-Roig, Miquel; Bauzá-Thorbrügge, Marco; Galmés-Pascual, Bel M; Capllonch-Amer, Gabriela; García-Palmer, Francisco J; Lladó, Isabel; Proenza, Ana M; Gianotti, Magdalena

2016-01-15

Considering the sexual dimorphism described in cardiac mitochondrial function and oxidative stress, we aimed to investigate the role of 17β-estradiol (E2) in these sex differences and the contribution of E2 receptors to these effects. As a model of chronic deprivation of ovarian hormones, we used ovariectomized (OVX) rats, half of which were treated with E2. Ovariectomy decreased markers of cardiac mitochondrial biogenesis and function and also increased oxidative stress, whereas E2 counteracted these effects. In H9c2 cardiomyocytes we observed that G-protein coupled estrogen receptor (GPER) agonist mimicked the effects of E2 in enhancing mitochondrial function and biogenesis, whereas GPER inhibitor neutralized them. These data suggest that E2 enhances mitochondrial function and decreases oxidative stress in cardiac muscle, thus it could be responsible for the sexual dimorphism observed in mitochondrial biogenesis and function in this tissue. These effects seem to be mediated through GPER stimulation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Control of mitochondrial biogenesis and function by the ubiquitin-proteasome system.

PubMed

Bragoszewski, Piotr; Turek, Michal; Chacinska, Agnieszka

2017-04-01

Mitochondria are pivotal organelles in eukaryotic cells. The complex proteome of mitochondria comprises proteins that are encoded by nuclear and mitochondrial genomes. The biogenesis of mitochondrial proteins requires their transport in an unfolded state with a high risk of misfolding. The mislocalization of mitochondrial proteins is deleterious to the cell. The electron transport chain in mitochondria is a source of reactive oxygen species that damage proteins. Mitochondrial dysfunction is linked to many pathological conditions and, together with the loss of cellular protein homeostasis (proteostasis), are hallmarks of ageing and ageing-related degeneration diseases. The pathogenesis of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, has been associated with mitochondrial and proteostasis failure. Thus, mitochondrial proteins require sophisticated surveillance mechanisms. Although mitochondria form a proteasome-exclusive compartment, multiple lines of evidence indicate a crucial role for the cytosolic ubiquitin-proteasome system (UPS) in the quality control of mitochondrial proteins. The proteasome affects mitochondrial proteins at stages of their biogenesis and maturity. The effects of the UPS go beyond the removal of damaged proteins and include the adjustment of mitochondrial proteome composition, the regulation of organelle dynamics and the protection of cellular homeostasis against mitochondrial failure. In turn, mitochondrial activity and mitochondrial dysfunction adjust the activity of the UPS, with implications at the cellular level. © 2017 The Authors.

Control of mitochondrial biogenesis and function by the ubiquitin–proteasome system

PubMed Central

Bragoszewski, Piotr; Turek, Michal

2017-01-01

Mitochondria are pivotal organelles in eukaryotic cells. The complex proteome of mitochondria comprises proteins that are encoded by nuclear and mitochondrial genomes. The biogenesis of mitochondrial proteins requires their transport in an unfolded state with a high risk of misfolding. The mislocalization of mitochondrial proteins is deleterious to the cell. The electron transport chain in mitochondria is a source of reactive oxygen species that damage proteins. Mitochondrial dysfunction is linked to many pathological conditions and, together with the loss of cellular protein homeostasis (proteostasis), are hallmarks of ageing and ageing-related degeneration diseases. The pathogenesis of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, has been associated with mitochondrial and proteostasis failure. Thus, mitochondrial proteins require sophisticated surveillance mechanisms. Although mitochondria form a proteasome-exclusive compartment, multiple lines of evidence indicate a crucial role for the cytosolic ubiquitin–proteasome system (UPS) in the quality control of mitochondrial proteins. The proteasome affects mitochondrial proteins at stages of their biogenesis and maturity. The effects of the UPS go beyond the removal of damaged proteins and include the adjustment of mitochondrial proteome composition, the regulation of organelle dynamics and the protection of cellular homeostasis against mitochondrial failure. In turn, mitochondrial activity and mitochondrial dysfunction adjust the activity of the UPS, with implications at the cellular level. PMID:28446709

Efficient mitochondrial biogenesis drives incomplete penetrance in Leber’s hereditary optic neuropathy

PubMed Central

Iommarini, Luisa; Giordano, Luca; Maresca, Alessandra; Pisano, Annalinda; Valentino, Maria Lucia; Caporali, Leonardo; Liguori, Rocco; Deceglie, Stefania; Roberti, Marina; Fanelli, Francesca; Fracasso, Flavio; Ross-Cisneros, Fred N.; D’Adamo, Pio; Hudson, Gavin; Pyle, Angela; Yu-Wai-Man, Patrick; Chinnery, Patrick F.; Zeviani, Massimo; Salomao, Solange R.; Berezovsky, Adriana; Belfort, Rubens; Ventura, Dora Fix; Moraes, Milton; Moraes Filho, Milton; Barboni, Piero; Sadun, Federico; De Negri, Annamaria; Sadun, Alfredo A.; Tancredi, Andrea; Mancini, Massimiliano; d’Amati, Giulia; Loguercio Polosa, Paola; Cantatore, Palmiro

2014-01-01

Leber’s hereditary optic neuropathy is a maternally inherited blinding disease caused as a result of homoplasmic point mutations in complex I subunit genes of mitochondrial DNA. It is characterized by incomplete penetrance, as only some mutation carriers become affected. Thus, the mitochondrial DNA mutation is necessary but not sufficient to cause optic neuropathy. Environmental triggers and genetic modifying factors have been considered to explain its variable penetrance. We measured the mitochondrial DNA copy number and mitochondrial mass indicators in blood cells from affected and carrier individuals, screening three large pedigrees and 39 independently collected smaller families with Leber’s hereditary optic neuropathy, as well as muscle biopsies and cells isolated by laser capturing from post-mortem specimens of retina and optic nerves, the latter being the disease targets. We show that unaffected mutation carriers have a significantly higher mitochondrial DNA copy number and mitochondrial mass compared with their affected relatives and control individuals. Comparative studies of fibroblasts from affected, carriers and controls, under different paradigms of metabolic demand, show that carriers display the highest capacity for activating mitochondrial biogenesis. Therefore we postulate that the increased mitochondrial biogenesis in carriers may overcome some of the pathogenic effect of mitochondrial DNA mutations. Screening of a few selected genetic variants in candidate genes involved in mitochondrial biogenesis failed to reveal any significant association. Our study provides a valuable mechanism to explain variability of penetrance in Leber’s hereditary optic neuropathy and clues for high throughput genetic screening to identify the nuclear modifying gene(s), opening an avenue to develop predictive genetic tests on disease risk and therapeutic strategies. PMID:24369379

Apple procyanidins promote mitochondrial biogenesis and proteoglycan biosynthesis in chondrocytes.

PubMed

Masuda, Isao; Koike, Masato; Nakashima, Shohei; Mizutani, Yu; Ozawa, Yusuke; Watanabe, Kenji; Sawada, Yoko; Sugiyama, Hiroshi; Sugimoto, Atsushi; Nojiri, Hidetoshi; Sashihara, Koichi; Yokote, Koutaro; Shimizu, Takahiko

2018-05-08

Apples are well known to have various benefits for the human body. Procyanidins are a class of polyphenols found in apples that have demonstrated effects on the circulatory system and skeletal organs. Osteoarthritis (OA) is a locomotive syndrome that is histologically characterized by cartilage degeneration associated with the impairment of proteoglycan homeostasis in chondrocytes. However, no useful therapy for cartilage degeneration has been developed to date. In the present study, we detected beneficial effects of apple polyphenols or their procyanidins on cartilage homeostasis. An in vitro assay revealed that apple polyphenols increased the activities of mitochondrial dehydrogenases associated with an increased copy number of mitochondrial DNA as well as the gene expression of peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), suggesting the promotion of PGC-1α-mediated mitochondrial biogenesis. Apple  procyanidins also enhanced proteoglycan biosynthesis with aggrecan upregulation in primary chondrocytes. Of note, oral treatment with apple procyanidins prevented articular cartilage degradation in OA model mice induced by mitochondrial dysfunction in chondrocytes. Our findings suggest that apple procyanidins are promising food components that inhibit OA progression by promoting mitochondrial biogenesis and proteoglycan homeostasis in chondrocytes.

Medium Chain Triglycerides enhances exercise endurance through the increased mitochondrial biogenesis and metabolism.

PubMed

Wang, Ying; Liu, Zhenzhen; Han, Yi; Xu, Jiping; Huang, Wen; Li, Zhaoshen

2018-01-01

Medium Chain Triglycerides (MCT) is a dietary supplement and usually used along with medications for treating food absorption disorders including diarrhea, steatorrhea and liver disease. It has been shown that MCT plays a role in lowering weight, and decreasing metabolic syndrome, abdominal obesity and inflammation. However, it is still unknown whether MCT enhances exercise endurance. Here, we demonstrated that MCT containing diet improves high temperature induced exercise performance impairment. We found that MCT up-regulates the expression and protein levels of genes involved in mitochondrial biogenesis and metabolism. Further investigation demonstrated that the increased mitochondrial biogenesis and metabolism is mediated through the activation of Akt and AMPK signaling pathways and inhibition of TGF-β signaling pathway. Collectively, our findings indicate a beneficial effect of dietary MCT in exercise performance through the increase of mitochondrial biogenesis and metabolism.

Medium Chain Triglycerides enhances exercise endurance through the increased mitochondrial biogenesis and metabolism

PubMed Central

Han, Yi; Xu, Jiping; Li, Zhaoshen

2018-01-01

Medium Chain Triglycerides (MCT) is a dietary supplement and usually used along with medications for treating food absorption disorders including diarrhea, steatorrhea and liver disease. It has been shown that MCT plays a role in lowering weight, and decreasing metabolic syndrome, abdominal obesity and inflammation. However, it is still unknown whether MCT enhances exercise endurance. Here, we demonstrated that MCT containing diet improves high temperature induced exercise performance impairment. We found that MCT up-regulates the expression and protein levels of genes involved in mitochondrial biogenesis and metabolism. Further investigation demonstrated that the increased mitochondrial biogenesis and metabolism is mediated through the activation of Akt and AMPK signaling pathways and inhibition of TGF-β signaling pathway. Collectively, our findings indicate a beneficial effect of dietary MCT in exercise performance through the increase of mitochondrial biogenesis and metabolism. PMID:29420554

The Effects of NAD+ on Apoptotic Neuronal Death and Mitochondrial Biogenesis and Function after Glutamate Excitotoxicity

PubMed Central

Wang, Xiaowan; Li, Hailong; Ding, Shinghua

2014-01-01

NAD+ is an essential co-enzyme for cellular energy metabolism and is also involved as a substrate for many cellular enzymatic reactions. It has been shown that NAD+ has a beneficial effect on neuronal survival and brain injury in in vitro and in vivo ischemic models. However, the effect of NAD+ on mitochondrial biogenesis and function in ischemia has not been well investigated. In the present study, we used an in vitro glutamate excitotoxicity model of primary cultured cortical neurons to study the effect of NAD+ on apoptotic neuronal death and mitochondrial biogenesis and function. Our results show that supplementation of NAD+ could effectively reduce apoptotic neuronal death, and apoptotic inducing factor translocation after neurons were challenged with excitotoxic glutamate stimulation. Using different approaches including confocal imaging, mitochondrial DNA measurement and Western blot analysis of PGC-1 and NRF-1, we also found that NAD+ could significantly attenuate glutamate-induced mitochondrial fragmentation and the impairment of mitochondrial biogenesis. Furthermore, NAD+ treatment effectively inhibited mitochondrial membrane potential depolarization and NADH redistribution after excitotoxic glutamate stimulation. Taken together, our results demonstrated that NAD+ is capable of inhibiting apoptotic neuronal death after glutamate excitotoxicity via preserving mitochondrial biogenesis and integrity. Our findings provide insights into potential neuroprotective strategies in ischemic stroke. PMID:25387075

N-acetylcysteine inhibits the up-regulation of mitochondrial biogenesis genes in livers from rats fed ethanol chronically

USDA-ARS?s Scientific Manuscript database

Background: Chronic ethanol (EtOH) administration to experimental animals induces hepatic oxidative stress and up-regulates mitochondrial biogenesis. The mechanisms by which chronic EtOH up-regulates mitochondrial biogenesis have not been fully explored. In this work, we hypothesized that oxidative ...

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

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

PubMed

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

2015-01-06

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

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

PubMed Central

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

2015-01-01

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

14,15-EET promotes mitochondrial biogenesis and protects cortical neurons against oxygen/glucose deprivation-induced apoptosis.

PubMed

Wang, Lai; Chen, Man; Yuan, Lin; Xiang, Yuting; Zheng, Ruimao; Zhu, Shigong

2014-07-18

14,15-Epoxyeicosatrienoic acid (14,15-EET), a metabolite of arachidonic acid, is enriched in the brain cortex and exerts protective effect against neuronal apoptosis induced by ischemia/reperfusion. Although apoptosis has been well recognized to be closely associated with mitochondrial biogenesis and function, it is still unclear whether the neuroprotective effect of 14,15-EET is mediated by promotion of mitochondrial biogenesis and function in cortical neurons under the condition of oxygen-glucose deprivation (OGD). In this study, we found that 14,15-EET improved cell viability and inhibited apoptosis of cortical neurons. 14,15-EET significantly increased the mitochondrial mass and the ratio of mitochondrial DNA to nuclear DNA. Key makers of mitochondrial biogenesis, peroxisome proliferator activator receptor gamma-coactivator 1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), were elevated at both mRNA and protein levels in the cortical neurons treated with 14,15-EET. Moreover, 14,15-EET markedly attenuated the decline of mitochondrial membrane potential, reduced ROS, while increased ATP synthesis. Knockdown of cAMP-response element binding protein (CREB) by siRNA blunted the up-regulation of PGC-1α and NRF-1 stimulated by 14,15-EET, and consequently abolished the neuroprotective effect of 14,15-EET. Our results indicate that 14,15-EET protects neurons from OGD-induced apoptosis by promoting mitochondrial biogenesis and function through CREB mediated activation of PGC-1α and NRF-1. Copyright © 2014 Elsevier Inc. All rights reserved.

Dysregulation of miRNAs in bladder cancer: altered expression with aberrant biogenesis procedure

PubMed Central

Dong, Fan; Xu, Tianyuan; Shen, Yifan; Zhong, Shan; Chen, Shanwen; Ding, Qiang; Shen, Zhoujun

2017-01-01

Aberrant expression profiles of miRNAs are widely observed in the clinical tissue specimens and urine samples as well as the blood samples of bladder cancer patients. These profiles are closely related to the pathological features of bladder cancer, such as the tumour stage/grade, metastasis, recurrence and chemo-sensitivity. MiRNA biogenesis forms the basis of miRNA expression and function, and its dysregulation has been shown to be essential for variations in miRNA expression profiles as well as tumourigenesis and cancer progression. In this review, we summarize the up-to-date and widely reported miRNAs in bladder cancer that display significantly altered expression. We then compare the miRNA expression profiles among three different sample types (tissue, urine and blood) from patients with bladder cancer. Moreover, for the first time, we outline the dysregulated miRNA biogenesis network in bladder cancer from different levels and analyse its possible relationship with aberrant miRNA expression and the pathological characteristics of the disease. PMID:28187437

Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

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

Saxena, Saurabh; Shukla, Dhananjay; Bansal, Anju, E-mail: anjubansaldipas@gmail.com

High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl{sub 2}), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl{sub 2} supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl{sub 2} supplementation in rats augmentedmore » the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl{sub 2} supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl{sub 2} for 15 days along with training. �

Redox and Reactive Oxygen Species Regulation of Mitochondrial Cytochrome c Oxidase Biogenesis

PubMed Central

Bourens, Myriam; Fontanesi, Flavia; Soto, Iliana C.; Liu, Jingjing

2013-01-01

Abstract Significance: Cytochrome c oxidase (COX), the last enzyme of the mitochondrial respiratory chain, is the major oxygen consumer enzyme in the cell. COX biogenesis involves several redox-regulated steps. The process is highly regulated to prevent the formation of pro-oxidant intermediates. Recent Advances: Regulation of COX assembly involves several reactive oxygen species and redox-regulated steps. These include: (i) Intricate redox-controlled machineries coordinate the expression of COX isoenzymes depending on the environmental oxygen concentration. (ii) COX is a heme A-copper metalloenzyme. COX copper metallation involves the copper chaperone Cox17 and several other recently described cysteine-rich proteins, which are oxidatively folded in the mitochondrial intermembrane space. Copper transfer to COX subunits 1 and 2 requires concomitant transfer of redox power. (iii) To avoid the accumulation of reactive assembly intermediates, COX is regulated at the translational level to minimize synthesis of the heme A-containing Cox1 subunit when assembly is impaired. Critical Issues: An increasing number of regulatory pathways converge to facilitate efficient COX assembly, thus preventing oxidative stress. Future Directions: Here we will review on the redox-regulated COX biogenesis steps and will discuss their physiological relevance. Forthcoming insights into the precise regulation of mitochondrial COX biogenesis in normal and stress conditions will likely open future perspectives for understanding mitochondrial redox regulation and prevention of oxidative stress. Antioxid. Redox Signal. 19, 1940–1952. PMID:22937827

Shear stress-induced mitochondrial biogenesis decreases the release of microparticles from endothelial cells.

PubMed

Kim, Ji-Seok; Kim, Boa; Lee, Hojun; Thakkar, Sunny; Babbitt, Dianne M; Eguchi, Satoru; Brown, Michael D; Park, Joon-Young

2015-08-01

The concept of enhancing structural integrity of mitochondria has emerged as a novel therapeutic option for cardiovascular disease. Flow-induced increase in laminar shear stress is a potent physiological stimulant associated with exercise, which exerts atheroprotective effects in the vasculature. However, the effect of laminar shear stress on mitochondrial remodeling within the vascular endothelium and its related functional consequences remain largely unknown. Using in vitro and in vivo complementary studies, here, we report that aerobic exercise alleviates the release of endothelial microparticles in prehypertensive individuals and that these salutary effects are, in part, mediated by shear stress-induced mitochondrial biogenesis. Circulating levels of total (CD31(+)/CD42a(-)) and activated (CD62E(+)) microparticles released by endothelial cells were significantly decreased (∼40% for both) after a 6-mo supervised aerobic exercise training program in individuals with prehypertension. In cultured human endothelial cells, laminar shear stress reduced the release of endothelial microparticles, which was accompanied by an increase in mitochondrial biogenesis through a sirtuin 1 (SIRT1)-dependent mechanism. Resveratrol, a SIRT1 activator, treatment showed similar effects. SIRT1 knockdown using small-interfering RNA completely abolished the protective effect of shear stress. Disruption of mitochondrial integrity by either antimycin A or peroxisome proliferator-activated receptor-γ coactivator-1α small-interfering RNA significantly increased the number of total, and activated, released endothelial microparticles, and shear stress restored these back to basal levels. Collectively, these data demonstrate a critical role of endothelial mitochondrial integrity in preserving endothelial homeostasis. Moreover, prolonged laminar shear stress, which is systemically elevated during aerobic exercise in the vessel wall, mitigates endothelial dysfunction by promoting

Acetyl-L-carnitine supplementation to old rats partially reverts the age-related mitochondrial decay of soleus muscle by activating peroxisome proliferator-activated receptor gamma coactivator-1alpha-dependent mitochondrial biogenesis.

PubMed

Pesce, Vito; Fracasso, Flavio; Cassano, Pierluigi; Lezza, Angela Maria Serena; Cantatore, Palmiro; Gadaleta, Maria Nicola

2010-01-01

The age-related decay of mitochondrial function is a major contributor to the aging process. We tested the effects of 2-month-daily acetyl-L-carnitine (ALCAR) supplementation on mitochondrial biogenesis in the soleus muscle of aged rats. This muscle is heavily dependent on oxidative metabolism. Mitochondrial (mt) DNA content, citrate synthase activity, transcript levels of some nuclear- and mitochondrial-coded genes (cytochrome c oxidase subunit IV [COX-IV], 16S rRNA, COX-I) and of some factors involved in the mitochondrial biogenesis signaling pathway (peroxisome proliferator-activated receptor gamma [PPARgamma] coactivator-1alpha [PGC-1alpha], mitochondrial transcription factor A mitochondrial [TFAM], mitochondrial transcription factor 2B [TFB2]), as well as the protein content of PGC-1alpha were determined. The results suggest that the ALCAR treatment in old rats activates PGC-1alpha-dependent mitochondrial biogenesis, thus partially reverting the age-related mitochondrial decay.

Endothelial AMPK Activation Induces Mitochondrial Biogenesis and Stress Adaptation via eNOS-Dependent mTORC1 Signaling

PubMed Central

Li, Chunying; Reif, Michaella M; Craige, Siobhan; Kant, Shashi; Keaney, John F.

2016-01-01

Metabolic stress sensors like AMP-activated protein kinase (AMPK) are known to confer stress adaptation and promote longevity in lower organisms. This study demonstrates that activating the metabolic stress sensor AMP-activated protein kinase (AMPK) in endothelial cells helps maintain normal cellular function by promoting mitochondrial biogenesis and stress adaptation. To better define the mechanisms whereby AMPK promotes endothelial stress resistance, we used 5-aminoimidazole-4-carboxamide riboside (AICAR) to chronically activate AMPK and observed stimulation of mitochondrial biogenesis in wild type mouse endothelium, but not in endothelium from endothelial nitric oxide synthase knockout (eNOS-null) mice. Interestingly, AICAR-enhanced mitochondrial biogenesis was blocked by pretreatment with the mammalian target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin. Further, AICAR stimulated mTORC1 as determined by phosphorylation of its known downstream effectors in wild type, but not eNOS-null, endothelial cells. Together these data indicate that eNOS is needed to couple AMPK activation to mTORC1 and thus promote mitochondrial biogenesis and stress adaptation in the endothelium. These data suggest a novel mechanism for mTORC1 activation that is significant for investigations in vascular dysfunction. PMID:26989010

Triiodothyronine induces lipid oxidation and mitochondrial biogenesis in rat Harderian gland.

PubMed

Santillo, A; Burrone, L; Falvo, S; Senese, R; Lanni, A; Chieffi Baccari, G

2013-10-01

The rat Harderian gland (HG) is an orbital gland producing a copious lipid secretion. Recent studies indicate that its secretory activity is regulated by thyroid hormones. In this study, we found that both isoforms of the thyroid hormone receptor (Trα (Thra) and Trβ (Thrb)) are expressed in rat HGs. Although Thra is expressed at a higher level, only Thrb is regulated by triiodothyronine (T3). Because T3 induces an increase in lipid metabolism in rat HGs, we investigated the effects of an animal's thyroid state on the expression levels of carnitine palmitoyltransferase-1A (Cpt1a) and carnitine palmitoyltransferase-1B (Cpt1b) and acyl-CoA oxidase (Acox1) (rate-limiting enzymes in mitochondrial and peroxisomal fatty acid oxidation respectively), as well as on the mitochondrial compartment, thereby correlating mitochondrial activity and biogenesis with morphological analysis. We found that hypothyroidism decreased the expression of Cpt1b and Acox1 mRNA, whereas the administration of T3 to hypothyroid rats increased transcript levels. Respiratory parameters and catalase protein levels provided further evidence that T3 modulates mitochondrial and peroxisomal activities. Furthermore, in hypothyroid rat HGs, the mitochondrial number and their total area decreased with respect to the controls, whereas the average area of the individual mitochondrion did not change. However, the average area of the individual mitochondrion was reduced by ∼50% in hypothyroid T3-treated HGs, and the mitochondrial number and the total area of the mitochondrial compartment increased. The mitochondrial morphometric data correlated well with the molecular results. Indeed, hypothyroid status did not modify the expression of mitochondrial biogenesis genes such as Ppargc1a, Nrf1 and Tfam, whereas T3 treatment increased the expression level of these genes.

Mitochondrial biogenesis and energy production in differentiating murine stem cells: a functional metabolic study.

PubMed

Han, Sungwon; Auger, Christopher; Thomas, Sean C; Beites, Crestina L; Appanna, Vasu D

2014-02-01

The significance of metabolic networks in guiding the fate of the stem cell differentiation is only beginning to emerge. Oxidative metabolism has been suggested to play a major role during this process. Therefore, it is critical to understand the underlying mechanisms of metabolic alterations occurring in stem cells to manipulate the ultimate outcome of these pluripotent cells. Here, using P19 murine embryonal carcinoma cells as a model system, the role of mitochondrial biogenesis and the modulation of metabolic networks during dimethyl sulfoxide (DMSO)-induced differentiation are revealed. Blue native polyacrylamide gel electrophoresis (BN-PAGE) technology aided in profiling key enzymes, such as hexokinase (HK) [EC 2.7.1.1], glucose-6-phosphate isomerase (GPI) [EC 5.3.1.9], pyruvate kinase (PK) [EC 2.7.1.40], Complex I [EC 1.6.5.3], and Complex IV [EC 1.9.3.1], that are involved in the energy budget of the differentiated cells. Mitochondrial adenosine triphosphate (ATP) production was shown to be increased in DMSO-treated cells upon exposure to the tricarboxylic acid (TCA) cycle substrates, such as succinate and malate. The increased mitochondrial activity and biogenesis were further confirmed by immunofluorescence microscopy. Collectively, the results indicate that oxidative energy metabolism and mitochondrial biogenesis were sharply upregulated in DMSO-differentiated P19 cells. This functional metabolic and proteomic study provides further evidence that modulation of mitochondrial energy metabolism is a pivotal component of the cellular differentiation process and may dictate the final destiny of stem cells.

Troxerutin attenuates diet-induced oxidative stress, impairment of mitochondrial biogenesis and respiratory chain complexes in mice heart.

PubMed

Rajagopalan, Geetha; Chandrasekaran, Sathiya Priya; Carani Venkatraman, Anuradha

2017-01-01

Mitochondrial abnormality is thought to play a key role in cardiac disease originating from the metabolic syndrome (MS). We evaluated the effect of troxerutin (TX), a semi-synthetic derivative of the natural bioflavanoid rutin, on the respiratory chain complex activity, oxidative stress, mitochondrial biogenesis and dynamics in heart of high fat, high fructose diet (HFFD) -induced mouse model of MS. Adult male Mus musculus mice of body weight 25-30 g were fed either control diet or HFFD for 60 days. Mice from each dietary regimen were divided into two groups on the 16th day and were treated or untreated with TX (150 mg/kg body weight [bw], per oral) for the next 45 days. At the end of experimental period, respiratory chain complex activity, uncoupling proteins (UCP)-2 and -3, mtDNA content, mitochondrial biogenesis and dynamics, oxidative stress markers and reactive oxygen species (ROS) generation were analyzed. Reduced mtDNA abundance with alterations in the expression of genes related to mitochondrial biogenesis and fission and fusion processes were observed in HFFD-fed mice. Disorganized and smaller mitochondria, reduction in complexes I, III and IV activities (by about 55%) and protein levels of UCP-2 (52%) and UCP-3 (46%) were noted in these mice. TX administration suppressed oxidative stress, improved the oxidative capacity and biogenesis and restored fission/fusion imbalance in the cardiac mitochondria of HFFD-fed mice. TX protects the myocardium by modulating the putative molecules of mitochondrial biogenesis and dynamics and by its anti-oxidant function in a mouse model of MS. © 2016 John Wiley & Sons Australia, Ltd.

Biogenesis of a Mitochondrial Outer Membrane Protein in Trypanosoma brucei: TARGETING SIGNAL AND DEPENDENCE ON A UNIQUE BIOGENESIS FACTOR.

PubMed

Bruggisser, Julia; Käser, Sandro; Mani, Jan; Schneider, André

2017-02-24

The mitochondrial outer membrane (OM) contains single and multiple membrane-spanning proteins that need to contain signals that ensure correct targeting and insertion into the OM. The biogenesis of such proteins has so far essentially only been studied in yeast and related organisms. Here we show that POMP10, an OM protein of the early diverging protozoan Trypanosoma brucei , is signal-anchored. Transgenic cells expressing variants of POMP10 fused to GFP demonstrate that the N-terminal membrane-spanning domain flanked by a few positively charged or neutral residues is both necessary and sufficient for mitochondrial targeting. Carbonate extraction experiments indicate that although the presence of neutral instead of positively charged residues did not interfere with POMP10 localization, it weakened its interaction with the OM. Expression of GFP-tagged POMP10 in inducible RNAi cell lines shows that its mitochondrial localization depends on pATOM36 but does not require Sam50 or ATOM40, the trypanosomal analogue of the Tom40 import pore. pATOM36 is a kinetoplastid-specific OM protein that has previously been implicated in the assembly of OM proteins and in mitochondrial DNA inheritance. In summary, our results show that although the features of the targeting signal in signal-anchored proteins are widely conserved, the protein machinery that mediates their biogenesis is not. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Escalating Methamphetamine Regimen Induces Compensatory Mechanisms, Mitochondrial Biogenesis, and GDNF Expression, in Substantia Nigra.

PubMed

Valian, Neda; Ahmadiani, Abolhassan; Dargahi, Leila

2017-06-01

Methamphetamine (MA) produces long-lasting deficits in dopaminergic neurons in the long-term use via several neurotoxic mechanisms. The effects of MA on mitochondrial biogenesis is less studied currently. So, we evaluated the effects of repeated escalating MA regimen on transcriptional factors involved in mitochondrial biogenesis and glial-derived neurotrophic factor (GDNF) expression in substantia nigra (SN) and striatum of rat. In male Wistar rats, increasing doses of MA (1-14 mg/kg) were administrated twice a day for 14 days. At the 1st, 14th, 28th, and 60th days after MA discontinuation, we measured the PGC1α, TFAM and NRF1 mRNA levels, indicator of mitochondrial biogenesis, and GDNF expression in SN and striatum. Furthermore, we evaluated the glial fibrillary acidic protein (GFAP) and Iba1 mRNA levels, and the levels of tyrosine hydroxylase (TH) and α-synuclein (α-syn) using immunohistochemistry and real-time polymerase chain reaction (PCR). We detected increments in PGC1α and TFAM mRNA levels in SN, but not striatum, and elevations in GDNF levels in SN immediately after MA discontinuation. We also observed increases in GFAP and Iba1 mRNA levels in SN on day 1 and increases in Iba1 mRNA on days 1 and 14 in striatum. Data analysis revealed that the number of TH + cells in the SN did not reduce in any time points, though TH mRNA levels was increased on day 1 after MA discontinuation in SN. These data show that repeated escalating MA induces several compensatory mechanisms, such as mitochondrial biogenesis and elevation in GDNF in SN. These mechanisms can reverse MA-induced neuroinflammation and prevent TH-immunoreactivity reduction in nigrostriatal pathway. J. Cell. Biochem. 118: 1369-1378, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

AKT3 controls mitochondrial biogenesis and autophagy via regulation of the major nuclear export protein CRM-1

PubMed Central

Corum, Daniel G.; Tsichlis, Philip N.; Muise-Helmericks, Robin C.

2014-01-01

Our previous work has shown that Akt3 is required for mitochondrial biogenesis in primary human endothelial cells (ECs) and in Akt3-null mice; Akt3 affects subcellular localization of peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α), the master regulator of mitochondrial biogenesis. The purpose of this study is to determine the mechanism by which Akt3 controls the subcellular distribution of PGC-1α and to explore the effect on mitochondrial biogenesis and turnover during angiogenesis. Here we use standard biochemical analyses and Akt3-knockdown strategies to show that Akt3 controls the stabilization of chromosome maintenance region-1 (CRM-1), the major nuclear export receptor. Site-directed mutagenesis and association analyses show that PGC-1α nuclear export is CRM-1 dependent. Akt3 knockdown and CRM-1 overexpression cause 3-fold reductions in PGC-1α target gene expression, compared to control levels. Akt3 inhibition causes autophagy, as measured by autophagosome formation, in a CRM-1-dependent, Akt1/mTOR-independent pathway. In vivo, Akt3-null and heterozygous mice show dose-dependent decreases in angiogenesis compared to wild-type littermates (∼5- and 2.5-fold decreases, respectively), as assessed by Matrigel plug assays. This correlates with an ∼1.5-fold decrease in mitochondrial Cox IV expression. Our studies suggest that Akt3 is a regulator of mitochondrial dynamics in the vasculature via regulation of CRM-1-dependent nuclear export.—Corum, D. G., Tsichlis, P. N., Muise-Helmericks, R. C. AKT3 controls mitochondrial biogenesis and autophagy via regulation of the major nuclear export protein CRM-1. PMID:24081905

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

PubMed

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

2016-10-01

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

Gamma rays induce a p53-independent mitochondrial biogenesis that is counter-regulated by HIF1α

PubMed Central

Bartoletti-Stella, A; Mariani, E; Kurelac, I; Maresca, A; Caratozzolo, M F; Iommarini, L; Carelli, V; Eusebi, L H; Guido, A; Cenacchi, G; Fuccio, L; Rugolo, M; Tullo, A; Porcelli, A M; Gasparre, G

2013-01-01

Mitochondrial biogenesis is an orchestrated process that presides to the regulation of the organelles homeostasis within a cell. We show that γ-rays, at doses commonly used in the radiation therapy for cancer treatment, induce an increase in mitochondrial mass and function, in response to a genotoxic stress that pushes cells into senescence, in the presence of a functional p53. Although the main effector of the response to γ-rays is the p53-p21 axis, we demonstrated that mitochondrial biogenesis is only indirectly regulated by p53, whose activation triggers a murine double minute 2 (MDM2)-mediated hypoxia-inducible factor 1α (HIF1α) degradation, leading to the release of peroxisome-proliferator activated receptor gamma co-activator 1β inhibition by HIF1α, thus promoting mitochondrial biogenesis. Mimicking hypoxia by HIF1α stabilization, in fact, blunts the mitochondrial response to γ-rays as well as the induction of p21-mediated cell senescence, indicating prevalence of the hypoxic over the genotoxic response. Finally, we also show in vivo that post-radiotherapy mitochondrial DNA copy number increase well correlates with lack of HIF1α increase in the tissue, concluding this may be a useful molecular tool to infer the trigger of a hypoxic response during radiotherapy, which may lead to failure of activation of cell senescence. PMID:23764844

Insulin-like growth factor 1 signaling is essential for mitochondrial biogenesis and mitophagy in cancer cells.

PubMed

Lyons, Amy; Coleman, Michael; Riis, Sarah; Favre, Cedric; O'Flanagan, Ciara H; Zhdanov, Alexander V; Papkovsky, Dmitri B; Hursting, Stephen D; O'Connor, Rosemary

2017-10-13

Mitochondrial activity and metabolic reprogramming influence the phenotype of cancer cells and resistance to targeted therapy. We previously established that an insulin-like growth factor 1 (IGF-1)-inducible mitochondrial UTP carrier (PNC1/SLC25A33) promotes cell growth. This prompted us to investigate whether IGF signaling is essential for mitochondrial maintenance in cancer cells and whether this contributes to therapy resistance. Here we show that IGF-1 stimulates mitochondrial biogenesis in a range of cell lines. In MCF-7 and ZR75.1 breast cancer cells, IGF-1 induces peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) and PGC-1α-related coactivator (PRC). Suppression of PGC-1β and PRC with siRNA reverses the effects of IGF-1 and disrupts mitochondrial morphology and membrane potential. IGF-1 also induced expression of the redox regulator nuclear factor-erythroid-derived 2-like 2 (NFE2L2 alias NRF-2). Of note, MCF-7 cells with acquired resistance to an IGF-1 receptor (IGF-1R) tyrosine kinase inhibitor exhibited reduced expression of PGC-1β, PRC, and mitochondrial biogenesis. Interestingly, these cells exhibited mitochondrial dysfunction, indicated by reactive oxygen species expression, reduced expression of the mitophagy mediators BNIP3 and BNIP3L, and impaired mitophagy. In agreement with this, IGF-1 robustly induced BNIP3 accumulation in mitochondria. Other active receptor tyrosine kinases could not compensate for reduced IGF-1R activity in mitochondrial protection, and MCF-7 cells with suppressed IGF-1R activity became highly dependent on glycolysis for survival. We conclude that IGF-1 signaling is essential for sustaining cancer cell viability by stimulating both mitochondrial biogenesis and turnover through BNIP3 induction. This core mitochondrial protective signal is likely to strongly influence responses to therapy and the phenotypic evolution of cancer. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle

PubMed Central

Cho, Yoshitake; Hazen, Bethany C.; Gandra, Paulo G.; Ward, Samuel R.; Schenk, Simon; Russell, Aaron P.; Kralli, Anastasia

2016-01-01

Skeletal muscle mitochondrial content and oxidative capacity are important determinants of muscle function and whole-body health. Mitochondrial content and function are enhanced by endurance exercise and impaired in states or diseases where muscle function is compromised, such as myopathies, muscular dystrophies, neuromuscular diseases, and age-related muscle atrophy. Hence, elucidating the mechanisms that control muscle mitochondrial content and oxidative function can provide new insights into states and diseases that affect muscle health. In past studies, we identified Perm1 (PPARGC1- and ESRR-induced regulator, muscle 1) as a gene induced by endurance exercise in skeletal muscle, and regulating mitochondrial oxidative function in cultured myotubes. The capacity of Perm1 to regulate muscle mitochondrial content and function in vivo is not yet known. In this study, we use adeno-associated viral (AAV) vectors to increase Perm1 expression in skeletal muscles of 4-wk-old mice. Compared to control vector, AAV1-Perm1 leads to significant increases in mitochondrial content and oxidative capacity (by 40–80%). Moreover, AAV1-Perm1–transduced muscles show increased capillary density and resistance to fatigue (by 33 and 31%, respectively), without prominent changes in fiber-type composition. These findings suggest that Perm1 selectively regulates mitochondrial biogenesis and oxidative function, and implicate Perm1 in muscle adaptations that also occur in response to endurance exercise.—Cho, Y., Hazen, B. C., Gandra, P. G., Ward, S. R., Schenk, S., Russell, A. P., Kralli, A. Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle. PMID:26481306

Principles of Exercise Prescription, and How They Influence Exercise-Induced Changes of Transcription Factors and Other Regulators of Mitochondrial Biogenesis.

PubMed

Granata, Cesare; Jamnick, Nicholas A; Bishop, David J

2018-04-19

Physical inactivity represents the fourth leading risk factor for mortality, and it has been linked with a series of chronic disorders, the treatment of which absorbs ~ 85% of healthcare costs in developed countries. Conversely, physical activity promotes many health benefits; endurance exercise in particular represents a powerful stimulus to induce mitochondrial biogenesis, and it is routinely used to prevent and treat chronic metabolic disorders linked with sub-optimal mitochondrial characteristics. Given the importance of maintaining a healthy mitochondrial pool, it is vital to better characterize how manipulating the endurance exercise dose affects cellular mechanisms of exercise-induced mitochondrial biogenesis. Herein, we propose a definition of mitochondrial biogenesis and the techniques available to assess it, and we emphasize the importance of standardizing biopsy timing and the determination of relative exercise intensity when comparing different studies. We report an intensity-dependent regulation of exercise-induced increases in nuclear peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein content, nuclear phosphorylation of p53 (serine 15), and PGC-1α messenger RNA (mRNA), as well as training-induced increases in PGC-1α and p53 protein content. Despite evidence that PGC-1α protein content plateaus within a few exercise sessions, we demonstrate that greater training volumes induce further increases in PGC-1α (and p53) protein content, and that short-term reductions in training volume decrease the content of both proteins, suggesting training volume is still a factor affecting training-induced mitochondrial biogenesis. Finally, training-induced changes in mitochondrial transcription factor A (TFAM) protein content are regulated in a training volume-dependent manner and have been linked with training-induced changes in mitochondrial content.

Rosiglitazone-Induced Mitochondrial Biogenesis in White Adipose Tissue Is Independent of Peroxisome Proliferator-Activated Receptor γ Coactivator-1α

PubMed Central

Pardo, Rosario; Enguix, Natàlia; Lasheras, Jaime; Feliu, Juan E.; Kralli, Anastasia; Villena, Josep A.

2011-01-01

Background Thiazolidinediones, a family of insulin-sensitizing drugs commonly used to treat type 2 diabetes, are thought to exert their effects in part by promoting mitochondrial biogenesis in white adipose tissue through the transcriptional coactivator PGC-1α (Peroxisome Proliferator-Activated Receptor γ Coactivator-1α). Methodology/Principal Findings To assess the role of PGC-1α in the control of rosiglitazone-induced mitochondrial biogenesis, we have generated a mouse model that lacks expression of PGC-1α specifically in adipose tissues (PGC-1α-FAT-KO mice). We found that expression of genes encoding for mitochondrial proteins involved in oxidative phosphorylation, tricarboxylic acid cycle or fatty acid oxidation, was similar in white adipose tissue of wild type and PGC-1α-FAT-KO mice. Furthermore, the absence of PGC-1α did not prevent the positive effect of rosiglitazone on mitochondrial gene expression or biogenesis, but it precluded the induction by rosiglitazone of UCP1 and other brown fat-specific genes in white adipose tissue. Consistent with the in vivo findings, basal and rosiglitazone-induced mitochondrial gene expression in 3T3-L1 adipocytes was unaffected by the knockdown of PGC-1α but it was impaired when PGC-1β expression was knockdown by the use of specific siRNA. Conclusions/Significance These results indicate that in white adipose tissue PGC-1α is dispensable for basal and rosiglitazone-induced mitochondrial biogenesis but required for the rosiglitazone-induced expression of UCP1 and other brown adipocyte-specific markers. Our study suggests that PGC-1α is important for the appearance of brown adipocytes in white adipose tissue. Our findings also provide evidence that PGC-1β and not PGC-1α regulates basal and rosiglitazone-induced mitochondrial gene expression in white adipocytes. PMID:22087241

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

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

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

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

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

, implying depression of the entire mitochondrial biogenesis. Results of Western blot analysis confirmed the reduced levels of the respiratory chain subunits that included mitochondrially encoded COX1 (47.5%; P = .004), COX2 (32.4%; P < .001), COX4 (26.6%; P < .001), and succinate dehydrogenase complex subunit A (65.8%; P = .03) as well as the structural outer membrane mitochondrial porin (33.1%; P < .001). Conversely, the levels of expression of 3 myogenic regulatory factors—muscle-specificmyogenic factor 5, myoblast determination 1, and myogenin—were higher in muscles from patients with SMA compared with muscles from age-matched controls (P < .05). CONCLUSIONS AND RELEVANCE Our results strongly support the conclusion that an altered regulation of myogenesis and a downregulated mitochondrial biogenesis contribute to pathologic change in the muscle of patients with SMA. Therapeutic strategies should aim at counteracting these changes. PMID:25844556

AKT3 controls mitochondrial biogenesis and autophagy via regulation of the major nuclear export protein CRM-1.

PubMed

Corum, Daniel G; Tsichlis, Philip N; Muise-Helmericks, Robin C

2014-01-01

Our previous work has shown that Akt3 is required for mitochondrial biogenesis in primary human endothelial cells (ECs) and in Akt3-null mice; Akt3 affects subcellular localization of peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α), the master regulator of mitochondrial biogenesis. The purpose of this study is to determine the mechanism by which Akt3 controls the subcellular distribution of PGC-1α and to explore the effect on mitochondrial biogenesis and turnover during angiogenesis. Here we use standard biochemical analyses and Akt3-knockdown strategies to show that Akt3 controls the stabilization of chromosome maintenance region-1 (CRM-1), the major nuclear export receptor. Site-directed mutagenesis and association analyses show that PGC-1α nuclear export is CRM-1 dependent. Akt3 knockdown and CRM-1 overexpression cause 3-fold reductions in PGC-1α target gene expression, compared to control levels. Akt3 inhibition causes autophagy, as measured by autophagosome formation, in a CRM-1-dependent, Akt1/mTOR-independent pathway. In vivo, Akt3-null and heterozygous mice show dose-dependent decreases in angiogenesis compared to wild-type littermates (~5- and 2.5-fold decreases, respectively), as assessed by Matrigel plug assays. This correlates with an ~1.5-fold decrease in mitochondrial Cox IV expression. Our studies suggest that Akt3 is a regulator of mitochondrial dynamics in the vasculature via regulation of CRM-1-dependent nuclear export.

ISCA1 is essential for mitochondrial Fe4S4 biogenesis in vivo.

PubMed

Beilschmidt, Lena Kristina; Ollagnier de Choudens, Sandrine; Fournier, Marjorie; Sanakis, Ioannis; Hograindleur, Marc-André; Clémancey, Martin; Blondin, Geneviève; Schmucker, Stéphane; Eisenmann, Aurélie; Weiss, Amélie; Koebel, Pascale; Messaddeq, Nadia; Puccio, Hélène; Martelli, Alain

2017-05-11

Mammalian A-type proteins, ISCA1 and ISCA2, are evolutionarily conserved proteins involved in iron-sulfur cluster (Fe-S) biogenesis. Recently, it was shown that ISCA1 and ISCA2 form a heterocomplex that is implicated in the maturation of mitochondrial Fe 4 S 4 proteins. Here we report that mouse ISCA1 and ISCA2 are Fe 2 S 2 -containing proteins that combine all features of Fe-S carrier proteins. We use biochemical, spectroscopic and in vivo approaches to demonstrate that despite forming a complex, ISCA1 and ISCA2 establish discrete interactions with components of the late Fe-S machinery. Surprisingly, knockdown experiments in mouse skeletal muscle and in primary cultures of neurons suggest that ISCA1, but not ISCA2, is required for mitochondrial Fe 4 S 4 proteins biogenesis. Collectively, our data suggest that cellular processes with different requirements for ISCA1, ISCA2 and ISCA1-ISCA2 complex seem to exist.

ISCA1 is essential for mitochondrial Fe4S4 biogenesis in vivo

PubMed Central

Beilschmidt, Lena Kristina; Ollagnier de Choudens, Sandrine; Fournier, Marjorie; Sanakis, Ioannis; Hograindleur, Marc-André; Clémancey, Martin; Blondin, Geneviève; Schmucker, Stéphane; Eisenmann, Aurélie; Weiss, Amélie; Koebel, Pascale; Messaddeq, Nadia; Puccio, Hélène; Martelli, Alain

2017-01-01

Mammalian A-type proteins, ISCA1 and ISCA2, are evolutionarily conserved proteins involved in iron–sulfur cluster (Fe–S) biogenesis. Recently, it was shown that ISCA1 and ISCA2 form a heterocomplex that is implicated in the maturation of mitochondrial Fe4S4 proteins. Here we report that mouse ISCA1 and ISCA2 are Fe2S2-containing proteins that combine all features of Fe–S carrier proteins. We use biochemical, spectroscopic and in vivo approaches to demonstrate that despite forming a complex, ISCA1 and ISCA2 establish discrete interactions with components of the late Fe–S machinery. Surprisingly, knockdown experiments in mouse skeletal muscle and in primary cultures of neurons suggest that ISCA1, but not ISCA2, is required for mitochondrial Fe4S4 proteins biogenesis. Collectively, our data suggest that cellular processes with different requirements for ISCA1, ISCA2 and ISCA1–ISCA2 complex seem to exist. PMID:28492233

Mitophagy is required for mitochondrial biogenesis and myogenic differentiation of C2C12 myoblasts.

PubMed

Sin, Jon; Andres, Allen M; Taylor, David J R; Weston, Thomas; Hiraumi, Yoshimi; Stotland, Aleksandr; Kim, Brandon J; Huang, Chengqun; Doran, Kelly S; Gottlieb, Roberta A

2016-01-01

Myogenesis is a crucial process governing skeletal muscle development and homeostasis. Differentiation of primitive myoblasts into mature myotubes requires a metabolic switch to support the increased energetic demand of contractile muscle. Skeletal myoblasts specifically shift from a highly glycolytic state to relying predominantly on oxidative phosphorylation (OXPHOS) upon differentiation. We have found that this phenomenon requires dramatic remodeling of the mitochondrial network involving both mitochondrial clearance and biogenesis. During early myogenic differentiation, autophagy is robustly upregulated and this coincides with DNM1L/DRP1 (dynamin 1-like)-mediated fragmentation and subsequent removal of mitochondria via SQSTM1 (sequestosome 1)-mediated mitophagy. Mitochondria are then repopulated via PPARGC1A/PGC-1α (peroxisome proliferator-activated receptor gamma, coactivator 1 alpha)-mediated biogenesis. Mitochondrial fusion protein OPA1 (optic atrophy 1 [autosomal dominant]) is then briskly upregulated, resulting in the reformation of mitochondrial networks. The final product is a myotube replete with new mitochondria. Respirometry reveals that the constituents of these newly established mitochondrial networks are better primed for OXPHOS and are more tightly coupled than those in myoblasts. Additionally, we have found that suppressing autophagy with various inhibitors during differentiation interferes with myogenic differentiation. Together these data highlight the integral role of autophagy and mitophagy in myogenic differentiation.

Developmental regulation of mitochondrial biogenesis and function in the mouse mammary gland during a prolonged lactation cycle

USDA-ARS?s Scientific Manuscript database

The regulation of mitochondrial biogenesis and function in the lactating mammary cell is poorly understood. The goal of this study was to use proteomics to relate temporal changes in mammary cell mitochondrial function during lactation to changes in the proteins that make up this organelle. The hypo...

Aberrant Mitochondrial Homeostasis in the Skeletal Muscle of Sedentary Older Adults

PubMed Central

Safdar, Adeel; Hamadeh, Mazen J.; Kaczor, Jan J.; Raha, Sandeep; deBeer, Justin; Tarnopolsky, Mark A.

2010-01-01

The role of mitochondrial dysfunction and oxidative stress has been extensively characterized in the aetiology of sarcopenia (aging-associated loss of muscle mass) and muscle wasting as a result of muscle disuse. What remains less clear is whether the decline in skeletal muscle mitochondrial oxidative capacity is purely a function of the aging process or if the sedentary lifestyle of older adult subjects has confounded previous reports. The objective of the present study was to investigate if a recreationally active lifestyle in older adults can conserve skeletal muscle strength and functionality, chronic systemic inflammation, mitochondrial biogenesis and oxidative capacity, and cellular antioxidant capacity. To that end, muscle biopsies were taken from the vastus lateralis of young and age-matched recreationally active older and sedentary older men and women (N = 10/group; ♀  =  ♂). We show that a physically active lifestyle is associated with the partial compensatory preservation of mitochondrial biogenesis, and cellular oxidative and antioxidant capacity in skeletal muscle of older adults. Conversely a sedentary lifestyle, associated with osteoarthritis-mediated physical inactivity, is associated with reduced mitochondrial function, dysregulation of cellular redox status and chronic systemic inflammation that renders the skeletal muscle intracellular environment prone to reactive oxygen species-mediated toxicity. We propose that an active lifestyle is an important determinant of quality of life and molecular progression of aging in skeletal muscle of the elderly, and is a viable therapy for attenuating and/or reversing skeletal muscle strength declines and mitochondrial abnormalities associated with aging. PMID:20520725

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.

Sex differences in mitochondrial biogenesis determine neuronal death and survival in response to oxygen glucose deprivation and reoxygenation

PubMed Central

2014-01-01

Background Mitochondrial dysfunction has been linked to neuronal death and a wide array of neurodegenerative diseases. Previously, we have shown sex differences in mitochondria-mediated cell death pathways following hypoxia-ischemia. However, the role of mitochondrial biogenesis in hypoxic-ischemic brain injury between male vs. female has not been studied yet. Results Primary cerebellar granule neurons (CGNs), isolated from P7 male and female mice (CD-1) segregated based on visual inspection of sex, were exposed to 2 h of oxygen glucose deprivation (OGD) followed by 6–24 h of reoxygenation (Reox). Mitochondrial membrane potential (ΔΨm) and cellular ATP levels were reduced significantly in XX CGNs as compared to XY CGNs. Mitochondrial DNA (mtDNA) content was increased (>2-fold) at 2 h OGD in XY CGNs and remained increased up to 24 h of Reox compared to XX neurons and normoxia controls. The expression of mitochondrial transcription factor A (Tfam), the nuclear respiratory factor-1 (NRF-1) and the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis, were up-regulated (2-fold, ***p < 0.001) in XY CGNs but slightly reduced or remained unchanged in XX neurons. Similarly, the TFAM and PGC-1α protein levels and the mitochondrial proteins HSP60 and COXIV were increased in XY neurons only. Supportively, a balanced stimulation of fusion (Mfn 1and Mfn 2) and fission (Fis 1 and Drp 1) genes and enhanced formation of donut-shaped mitochondria were observed in XY CGNs vs. XX neurons (**p < 0.01). Conclusions Our results demonstrate that OGD/Reox alters mitochondrial biogenesis and morphological changes in a sex-specific way, influencing neuronal injury/survival differently in both sexes. PMID:24410996

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

PubMed

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

2015-06-01

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

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

PubMed Central

Scholpa, Natalie E.

2017-01-01

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

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

PubMed

Scholpa, Natalie E; Schnellmann, Rick G

2017-12-01

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

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

PubMed Central

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

2012-01-01

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

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

PubMed

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

2017-09-01

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

Long-term high-fat-diet feeding induces skeletal muscle mitochondrial biogenesis in rats in a sex-dependent and muscle-type specific manner

PubMed Central

2012-01-01

Background Mitochondrial dysfunction is thought to play a crucial role in the etiology of insulin resistance, in which skeletal muscle is the main tissue contributor. Sex differences in skeletal muscle insulin and antioxidant responses to high-fat-diet (HFD) feeding have been described. The aim of this study was to elucidate whether there is a sex dimorphism in the effects of HFD feeding on skeletal muscle mitochondrial biogenesis and on the adiponectin signaling pathway, as well as the influence of the muscle type (oxidative or glycolytic). Methods Gastrocnemius and soleus muscles of male and female Wistar rats of 2 months of age fed with a high-fat-diet (HFD) or a low fat diet for 26 weeks were used. Mitochondrial biogenesis and oxidative damage markers, oxidative capacity and antioxidant defences were analyzed. Serum insulin sensitivity parameters and the levels of proteins involved in adiponectin signaling pathway were also determined. Results HFD feeding induced mitochondrial biogenesis in both sexes, but to a higher degree in male rats. Although HFD female rats showed greater antioxidant protection and maintained a better insulin sensitivity profile than their male counterparts, both sexes showed an impaired response to adiponectin, which was more evident in gastrocnemius muscle. Conclusions We conclude that HFD rats may induce skeletal muscle mitochondrial biogenesis as an attempt to compensate the deleterious consequences of adiponectin and insulin resistance on oxidative metabolism, and that the effects of HFD feeding are sex-dependent and muscle-type specific. PMID:22353542

Testosterone Plus Low-Intensity Physical Training in Late Life Improves Functional Performance, Skeletal Muscle Mitochondrial Biogenesis, and Mitochondrial Quality Control in Male Mice

PubMed Central

Guo, Wen; Wong, Siu; Li, Michelle; Liang, Wentao; Liesa, Marc; Serra, Carlo; Jasuja, Ravi; Bartke, Andrzej; Kirkland, James L.; Shirihai, Orian; Bhasin, Shalender

2012-01-01

Testosterone supplementation increases muscle mass in older men but has not been shown to consistently improve physical function and activity. It has been hypothesized that physical exercise is required to induce the adaptations necessary for translation of testosterone-induced muscle mass gain into functional improvements. However, the effects of testosterone plus low intensity physical exercise training (T/PT) on functional performance and bioenergetics are unknown. In this pilot study, we tested the hypothesis that combined administration of T/PT would improve functional performance and bioenergetics in male mice late in life more than low-intensity physical training alone. 28-month old male mice were randomized to receive T/PT or vehicle plus physical training (V/PT) for 2 months. Compare to V/PT control, administration of T/PT was associated with improvements in muscle mass, grip strength, spontaneous physical movements, and respiratory activity. These changes were correlated with increased mitochondrial DNA copy number and expression of markers for mitochondrial biogenesis. Mice receiving T/PT also displayed increased expression of key elements for mitochondrial quality control, including markers for mitochondrial fission-and-fusion and mitophagy. Concurrently, mice receiving T/PT also displayed increased expression of markers for reduced tissue oxidative damage and improved muscle quality. Conclusion: Testosterone administered with low-intensity physical training improves grip strength, spontaneous movements, and respiratory activity. These functional improvements were associated with increased muscle mitochondrial biogenesis and improved mitochondrial quality control. PMID:23240002

Multi-omics Reveal Specific Targets of the RNA-Binding Protein Puf3p and Its Orchestration of Mitochondrial Biogenesis.

PubMed

Lapointe, Christopher P; Stefely, Jonathan A; Jochem, Adam; Hutchins, Paul D; Wilson, Gary M; Kwiecien, Nicholas W; Coon, Joshua J; Wickens, Marvin; Pagliarini, David J

2018-01-24

Coenzyme Q (CoQ) is a redox-active lipid required for mitochondrial oxidative phosphorylation (OxPhos). How CoQ biosynthesis is coordinated with the biogenesis of OxPhos protein complexes is unclear. Here, we show that the Saccharomyces cerevisiae RNA-binding protein (RBP) Puf3p regulates CoQ biosynthesis. To establish the mechanism for this regulation, we employed a multi-omic strategy to identify mRNAs that not only bind Puf3p but also are regulated by Puf3p in vivo. The CoQ biosynthesis enzyme Coq5p is a critical Puf3p target: Puf3p regulates the abundance of Coq5p and prevents its detrimental hyperaccumulation, thereby enabling efficient CoQ production. More broadly, Puf3p represses a specific set of proteins involved in mitochondrial protein import, translation, and OxPhos complex assembly (pathways essential to prime mitochondrial biogenesis). Our data reveal a mechanism for post-transcriptionally coordinating CoQ production with OxPhos biogenesis, and they demonstrate the power of multi-omics for defining genuine targets of RBPs. Copyright © 2017 Elsevier Inc. All rights reserved.

Elucidation of the therapeutic role of mitochondrial biogenesis transducers NRF-1 in the regulation of renal fibrosis

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

Hsieh, Pei-Fang; Graduate Institute of Medical Laboratory Science and Biotechnology, Chung Hwa University of Medical Technology, Tainan, Taiwan; Liu, Shu-Fen

Background: Mitochondrial dysfunction is a newly established risk factor for the development of renal fibrosis. Cell survival and injury repair is facilitated by mitochondrial biogenesis. Nuclear respiratory factor 1 (NRF-1) is a transcriptional regulation factor that plays a central role in the regulation of mitochondrial biogenesis. However, the transcription factor of this process in renal fibrosis is unknown. Thus, we hereby discussed the correlations of NRF-1 and renal interstitial fibrosis. Materials and methods: In vitro fibrosis model was established by treatment with transforming growth factor-β1 (TGF-β1) in NRK-49F (Normal Rat kidney fibroblast). We investigated the ROS production, mitochondrial biogenesis andmore » fibrogenic marker (e.q. fibronectin) during the progression of renal fibrosis by kit and Western blotting assay. Here, we used that two distinct mechanisms regulate NRF-1 activation and degradation of NRF-1. NRF-1 was transfect by pcDNA-NRF-1 overexpression gene to evaluate the NRF-1 activity of the therapeutic effect in renal fibrosis. In addition, NRF-1 was silenced by shRNA-NRF-1 to evaluate the significance of NRF-1. ELISA was used to evaluate the secreted fibronectin. Immunofluorescence staining was used to assay the in situ expression of proteins (e.g. fibronectin, NRF-1). Results: Under renal fibrosis conditions, TGF-β1 (5 ng/ml) increased ROS. Simultaneously, TGF-β1-induced extracellular fibronectin by ELISA assay. In addition, TGF-β1 decreased expression of mitochondrial biogenesis. This is the first time to demonstrate that expression of NRF-1 is significantly decreased in renal fibrosis. However, NRK49F was a transfection with pcDNA-NRF-1 (2 μg/ml) expression vector dramatically reverse TGF-β1-induced cellular fibrosis concomitantly with the suppression of fibronectin (both intracellular and extracellular fibronectin). More importantly, transfection with shRNA-NRF-1 (2 μg/ml) significantly increased the expression of

Elucidation of the therapeutic role of mitochondrial biogenesis transducers NRF-1 in the regulation of renal fibrosis.

PubMed

Hsieh, Pei-Fang; Liu, Shu-Fen; Hung, Tsung-Jen; Hung, Chien-Ya; Liu, Guo-Zheng; Chuang, Lea-Yea; Chen, Mei-Fen; Wang, Jue-Long; Shi, Ming-Der; Hsu, Chen Hung; Shiue, Yow-Ling; Yang, Yu-Lin

2016-11-15

Mitochondrial dysfunction is a newly established risk factor for the development of renal fibrosis. Cell survival and injury repair is facilitated by mitochondrial biogenesis. Nuclear respiratory factor 1 (NRF-1) is a transcriptional regulation factor that plays a central role in the regulation of mitochondrial biogenesis. However, the transcription factor of this process in renal fibrosis is unknown. Thus, we hereby discussed the correlations of NRF-1 and renal interstitial fibrosis. In vitro fibrosis model was established by treatment with transforming growth factor-β1 (TGF-β1) in NRK-49F (Normal Rat kidney fibroblast). We investigated the ROS production, mitochondrial biogenesis and fibrogenic marker (e.q. fibronectin) during the progression of renal fibrosis by kit and Western blotting assay. Here, we used that two distinct mechanisms regulate NRF-1 activation and degradation of NRF-1. NRF-1 was transfect by pcDNA-NRF-1 overexpression gene to evaluate the NRF-1 activity of the therapeutic effect in renal fibrosis. In addition, NRF-1 was silenced by shRNA-NRF-1 to evaluate the significance of NRF-1. ELISA was used to evaluate the secreted fibronectin. Immunofluorescence staining was used to assay the in situ expression of proteins (e.g. fibronectin, NRF-1). Under renal fibrosis conditions, TGF-β1 (5ng/ml) increased ROS. Simultaneously, TGF-β1-induced extracellular fibronectin by ELISA assay. In addition, TGF-β1 decreased expression of mitochondrial biogenesis. This is the first time to demonstrate that expression of NRF-1 is significantly decreased in renal fibrosis. However, NRK49F was a transfection with pcDNA-NRF-1 (2μg/ml) expression vector dramatically reverse TGF-β1-induced cellular fibrosis concomitantly with the suppression of fibronectin (both intracellular and extracellular fibronectin). More importantly, transfection with shRNA-NRF-1 (2μg/ml) significantly increased the expression of fibronectin of both intercellular and extracellular origins

Strawberry consumption improves aging-associated impairments, mitochondrial biogenesis and functionality through the AMP-activated protein kinase signaling cascade.

PubMed

Giampieri, Francesca; Alvarez-Suarez, Josè M; Cordero, Mario D; Gasparrini, Massimiliano; Forbes-Hernandez, Tamara Y; Afrin, Sadia; Santos-Buelga, Celestino; González-Paramás, Ana M; Astolfi, Paola; Rubini, Corrado; Zizzi, Antonio; Tulipani, Sara; Quiles, Josè L; Mezzetti, Bruno; Battino, Maurizio

2017-11-01

Dietary polyphenols have been recently proposed as activators of the AMP-activated protein kinase (AMPK) signaling pathway and this fact might explain the relationship between the consumption of polyphenol-rich foods and the slowdown of the progression of aging. In the present work, the effects of strawberry consumption were evaluated on biomarkers of oxidative damage and on aging-associated reductions in mitochondrial function and biogenesis for 8weeks in old rats. Strawberry supplementation increased antioxidant enzyme activities, mitochondrial biomass and functionality, and decreased intracellular ROS levels and biomarkers of protein, lipid and DNA damage (P<0.05). Furthermore, a significant (P<0.05) increase in the expression of the AMPK cascade genes, involved in mitochondrial biogenesis and antioxidant defences, was also detected after strawberry intake. These in vivo results were then verified in vitro on HepG2 cells, confirming the involvement of AMPK in the beneficial effects exerted by strawberry against aging progression. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inhibition of akt phosphorylation diminishes mitochondrial biogenesis regulators, tricarboxylic acid cycle activity and exacerbates recognition memory deficit in rat model of Alzheimer's disease.

PubMed

Shaerzadeh, Fatemeh; Motamedi, Fereshteh; Khodagholi, Fariba

2014-11-01

3-Methyladenine (3-MA), as a PI3K inhibitor, is widely used for inhibition of autophagy. Inhibition of PI3K class I leads to inhibition of Akt phosphorylation, a central molecule involved in diverse arrays of intracellular cascades in nervous system. Accordingly, in the present study, we aimed to determine the alterations of specific mitochondrial biogenesis markers and mitochondrial function in 3-MA-injected rats following amyloid beta (Aβ) insult. Our data revealed that inhibition of Akt phosphorylation downregulates master regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Our data also showed that decrease in PGC-1α level presumably is due to decrease in the phosphorylation of cAMP-response element binding and AMP-activated kinase, two upstream activators of PGC-1α. As a consequence, the level of some mitochondrial biogenesis factors including nuclear respiratory factor-1, mitochondrial transcription factor A, and Cytochrome c decreased significantly. Also, activities of tricarboxylic acid cycle (TCA) enzymes such as Aconitase, a-ketoglutarate dehydrogenase, and malate dehydrogenase reduced in the presence of 3-MA with or without Aβ insult. Decrease in mitochondrial biogenesis factors and TCA enzyme activity in the rats receiving 3-MA and Aβ were more compared to the rats that received either alone; indicating the additive destructive effects of these two agents. In agreement with our molecular results, data obtained from behavioral test (using novel objective recognition test) indicated that inhibition of Akt phosphorylation with or without Aβ injection impaired novel recognition (non-spatial) memory. Our results suggest that 3-MA amplified deleterious effects of Aβ by targeting central molecule Akt.

Defects in Mitochondrial Fatty Acid Synthesis Result in Failure of Multiple Aspects of Mitochondrial Biogenesis in Saccharomyces cerevisiae

PubMed Central

Kursu, V. A. Samuli; Pietikäinen, Laura P.; Fontanesi, Flavia; Aaltonen, Mari J.; Suomi, Fumi; Nair, Remya Raghavan; Schonauer, Melissa S.; Dieckmann, Carol L.; Barrientos, Antoni; Hiltunen, J. Kalervo; Kastaniotis, Alexander J.

2014-01-01

Summary Mitochondrial fatty acid synthesis (mtFAS) shares acetyl-CoA with the Krebs cycle as a common substrate and is required for the production of octanoic acid (C8) precursors of lipoic acid (LA) in mitochondria. MtFAS is a conserved pathway essential for respiration. In a genetic screen in Saccharomyces cerevisiae designed to further elucidate the physiological role of mtFAS, we isolated mutants with defects in mitochondrial post-translational gene expression processes, indicating a novel link to mitochondrial gene expression and respiratory chain biogenesis. In our ensuing analysis, we show that mtFAS, but not lipoylation per se, is required for respiratory competence. We demonstrate that mtFAS is required for mRNA splicing, mitochondrial translation and respiratory complex assembly, and provide evidence that not LA per se, but fatty acids longer than C8 play a role in these processes. We also show that mtFAS- and LA-deficient strains suffer from a mild heme deficiency that may contribute to the respiratory complex assembly defect. Based on our data and previously published information, we propose a model implicating mtFAS as a sensor for mitochondrial acetyl-CoA availability and a coordinator of nuclear and mitochondrial gene expression by adapting the mitochondrial compartment to changes in the metabolic status of the cell. PMID:24102902

Defects in mitochondrial fatty acid synthesis result in failure of multiple aspects of mitochondrial biogenesis in Saccharomyces cerevisiae.

PubMed

Kursu, V A Samuli; Pietikäinen, Laura P; Fontanesi, Flavia; Aaltonen, Mari J; Suomi, Fumi; Raghavan Nair, Remya; Schonauer, Melissa S; Dieckmann, Carol L; Barrientos, Antoni; Hiltunen, J Kalervo; Kastaniotis, Alexander J

2013-11-01

Mitochondrial fatty acid synthesis (mtFAS) shares acetyl-CoA with the Krebs cycle as a common substrate and is required for the production of octanoic acid (C8) precursors of lipoic acid (LA) in mitochondria. MtFAS is a conserved pathway essential for respiration. In a genetic screen in Saccharomyces cerevisiae designed to further elucidate the physiological role of mtFAS, we isolated mutants with defects in mitochondrial post-translational gene expression processes, indicating a novel link to mitochondrial gene expression and respiratory chain biogenesis. In our ensuing analysis, we show that mtFAS, but not lipoylation per se, is required for respiratory competence. We demonstrate that mtFAS is required for mRNA splicing, mitochondrial translation and respiratory complex assembly, and provide evidence that not LA per se, but fatty acids longer than C8 play a role in these processes. We also show that mtFAS- and LA-deficient strains suffer from a mild haem deficiency that may contribute to the respiratory complex assembly defect. Based on our data and previously published information, we propose a model implicating mtFAS as a sensor for mitochondrial acetyl-CoA availability and a co-ordinator of nuclear and mitochondrial gene expression by adapting the mitochondrial compartment to changes in the metabolic status of the cell. © 2013 John Wiley & Sons Ltd.

CTRP9 induces mitochondrial biogenesis and protects high glucose-induced endothelial oxidative damage via AdipoR1 -SIRT1- PGC-1α activation.

PubMed

Cheng, Liang; Li, Bin; Chen, Xu; Su, Jie; Wang, Hongbing; Yu, Shiqiang; Zheng, Qijun

2016-09-02

Vascular lesions caused by endothelial dysfunction are the most common and serious complication of diabetes. The vasoactive potency of CTRP9 has been reported in our previous study via nitric oxide (NO) production. However, the effect of CTRP9 on vascular endothelial cells remains unknown. This study aimed to investigate the protection role of CTRP9 in the primary aortic vascular endothelial cells and HAECs under high-glucose condition. We found that the aortic vascular endothelial cells isolated from mice fed with a high fat diet generated more ROS production than normal cells, along with decreased mitochondrial biogenesis, which was also found in HAECs treated with high glucose. However, the treatment of CTPR9 significantly reduced ROS production and increased the activities of endogenous antioxidant enzymes, the expression of PGC-1α, NRF1, TFAM, ATP5A1 and SIRT1, and the activity of cytochrome c oxidase, indicating an induction of mitochondrial biogenesis. Furthermore, silencing the expression of SIRT1 in HAECs impeded the effect of CTRP9 on mitochondrial biogenesis, while silencing the expression of AdipoR1 in HAECs reversed the expression of SIRT1 and PGC-1α. Based on these findings, this study showed that CTRP9 might induce mitochondrial biogenesis and protect high glucose-induced endothelial oxidative damage via AdipoR1-SIRT1-PGC-1α signaling pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of type 5-phosphodiesterase inhibition on energy metabolism and mitochondrial biogenesis in human adipose tissue ex vivo.

PubMed

De Toni, L; Strapazzon, G; Gianesello, L; Caretta, N; Pilon, C; Bruttocao, A; Foresta, C

2011-11-01

An excess of adipose tissue (AT) in obese individuals is linked to increased cardiovascular risk and mitochondria have been shown to be defective in the muscle and AT of patients with metabolic disorders such as obesity and Type 2 diabetes. Nitric oxide (NO) generated by endothelial NO synthase (eNOS) plays a role in mitochondrial biogenesis through cyclic-GMP (cGMP). AT harbors the whole molecular signaling pathway of NO, together with type 5-phosphodiesterase (PDE- 5), the main cGMP catabolising enzyme. Our aim was to evaluate the effect of the modulation of NO pathway, through PDE-5 inhibition, on energy metabolism and mitochondria biogenesis in human omental AT. Cultured human omental AT was stimulated with PDE-5 inhibitor, vardenafil, at different concentration for 24 and 72 h. Analysis of the expression of both key-regulator genes of adipocyte metabolism and mitochondria-biogenesis markers was performed. We found an increased gene expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), adiponectin, and proliferator- activated receptor gamma coactivator-1 α (PGC-1α) after a 24-h stimulation with vardenafil at the lowest concentration employed compared to controls (p<0.05). After 72 h of stimulation, a significant increase of mitochondrial DNA was found compared to control samples (p<0.05). Our data suggest that PDE-5 inhibition could have an impact on mitochondrial content of human AT suggesting a positive effect on energy metabolism and adding new elements in the comprehension of AT pathophysiology.

Osthole attenuates spinal cord ischemia-reperfusion injury through mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction in rats.

PubMed

Zhou, Yue-fei; Li, Liang; Feng, Feng; Yuan, Hua; Gao, Da-kuan; Fu, Luo-an; Fei, Zhou

2013-12-01

Osthole, the main bioactive compounds isolated from the traditional Chinese medical herb broad Cnidium monnieri (L.) cusson, has been shown to exert spectrum of pharmacologic activities. The aim of this study was to investigate the potential neuroprotective effects of osthole against spinal cord ischemia-reperfusion injury in rats. Osthole was administrated at the concentration of 0.1, 1, 10, 50, or 200 mg/kg (intraperitoneally) 1 h before spinal cord ischemia. The effects on spinal cord injury were measured by spinal cord water content, infarct volume, hematoxylin and eosin staining, and neurologic assessment. Mitochondria were purified from injured spinal cord tissue to determine mitochondrial function. We found that treatment with osthole (10 and 50 mg/kg) significantly decreased spinal cord water content and infarct volume, preserved normal motor neurons, and improved neurologic functions. These protective effects can be also observed even if the treatment was delayed to 4 h after reperfusion. Osthole treatment preserved mitochondrial membrane potential level, reduced reactive oxygen species production, increased adenosine triphosphate generation, and inhibited cytochrome c release in mitochondrial samples. Moreover, osthole increased mitochondria respiratory chain complex activities in spinal cord tissue, with no effect on mitochondrial DNA content and the expression of mitochondrial-specific transcription factors. All these findings demonstrate the neuroprotective effect of osthole in spinal cord ischemia-reperfusion injury model and suggest that oshtole-induced neuroprotection was mediated by mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction. Copyright © 2013 Elsevier Inc. All rights reserved.

Role of microRNA-130b in placental PGC-1α/TFAM mitochondrial biogenesis pathway

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

Jiang, Shaoning; Teague, April M.; Tryggestad, Jeanie B.

Diabetes during pregnancy is associated with abnormal placenta mitochondrial function and increased oxidative stress, which affect fetal development and offspring long-term health. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master regulator of mitochondrial biogenesis and energy metabolism. The molecular mechanisms underlying the regulation of PGC-1α in placenta in the context of diabetes remain unclear. The present study examined the role of microRNA 130b (miR-130b-3p) in regulating PGC-1α expression and oxidative stress in a placental trophoblastic cell line (BeWo). Prolonged exposure of BeWo cells to high glucose mimicking hyperglycemia resulted in decreased protein abundance of PGC-1α and its downstream factor, mitochondrialmore » transcription factor A (TFAM). High glucose treatment increased the expression of miR-130b-3p in BeWo cells, as well as exosomal secretion of miR-130b-3p. Transfection of BeWo cells with miR-130b-3p mimic reduced the abundance of PGC-1α, whereas inhibition of miR-130b-3p increased PGC-1α expression in response to high glucose, suggesting a role for miR-130b-3p in mediating high glucose-induced down regulation of PGC-1α expression. In addition, miR-130b-3p anti-sense inhibitor increased TFAM expression and reduced 4-hydroxynonenal (4-HNE)-induced production of reactive oxygen species (ROS). Taken together, these findings reveal that miR-130b-3p down-regulates PGC-1α expression in placental trophoblasts, and inhibition of miR-130b-3p appears to improve mitochondrial biogenesis signaling and protect placental trophoblast cells from oxidative stress. - Highlights: • High glucose reduces PGC-1α and TFAM proteins in trophoblast BeWo cells. • miR-130b-3p mediates high glucose-induced decrease in PGC-1α abundance. • Inhibition of miR-130b-3p improves mitochondrial biogenesis signaling. • Inhibition of miR-130b-3p protects trophoblasts against oxidative stress.« less

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

PubMed Central

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

2013-01-01

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

Leptin Modulates Mitochondrial Function, Dynamics and Biogenesis in MCF-7 Cells.

PubMed

Blanquer-Rosselló, M Mar; Santandreu, Francisca M; Oliver, Jordi; Roca, Pilar; Valle, Adamo

2015-09-01

The adipokine leptin, known for its key role in the control of energy metabolism, has been shown to be involved in both normal and tumoral mammary growth. One of the hallmarks of cancer is an alteration of tumor metabolism since cancerous cells must rewire metabolism to satisfy the demands of growth and proliferation. Considering the sensibility of breast cancer cells to leptin, the objective of this study was to explore the effects of this adipokine on their metabolism. To this aim, we treated the MCF-7 breast cancer cell line with 50 ng/mL leptin and analyzed several features related to cellular and mitochondrial metabolism. As a result, leptin increased cell proliferation, shifted ATP production from glycolysis to mitochondria and decreased the levels of the glycolytic end-product lactate. We observed an improvement in ADP-dependent oxygen consumption and an amelioration of oxidative stress without changes in total mitochondrial mass or specific oxidative phosphorylation (OXPHOS) complexes. Furthermore, RT-PCR and western blot showed an up-regulation for genes and proteins related to biogenesis and mitochondrial dynamics. This expression signature, together with an increased mitophagy observed by confocal microscopy suggests that leptin may improve mitochondrial quality and function. Taken together, our results propose that leptin may improve bioenergetic efficiency by avoiding the production of reactive oxygen species (ROS) and conferring benefits for growth and survival of MCF-7 breast cancer cells. © 2015 Wiley Periodicals, Inc.

Quercetin protects against aluminium induced oxidative stress and promotes mitochondrial biogenesis via activation of the PGC-1α signaling pathway.

PubMed

Sharma, Deep Raj; Sunkaria, Aditya; Wani, Willayat Yousuf; Sharma, Reeta Kumari; Verma, Deepika; Priyanka, Kumari; Bal, Amanjit; Gill, Kiran Dip

2015-12-01

The present investigation was carried out to elucidate a possible molecular mechanism related to the protective effect of quercetin administration against aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of PGC-1α and its downstream targets, i.e. NRF-1, NRF-2 and Tfam in mitochondrial biogenesis. Aluminium lactate (10mg/kg b.wt./day) was administered intragastrically to rats, which were pre-treated with quercetin 6h before aluminium (10mg/kg b.wt./day, intragastrically) for 12 weeks. We found a decrease in ROS levels, mitochondrial DNA oxidation and citrate synthase activity in the hippocampus (HC) and corpus striatum (CS) regions of rat brain treated with quercetin. Besides this an increase in the mRNA levels of the mitochondrial encoded subunits - ND1, ND2, ND3, Cyt b, COX1, COX3 and ATPase6 along with increased expression of nuclear encoded subunits COX4, COX5A and COX5B of electron transport chain (ETC). In quercetin treated group an increase in the mitochondrial DNA copy number and mitochondrial content in both the regions of rat brain was observed. The PGC-1α was up regulated in quercetin treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α. Electron microscopy results revealed a significant decrease in the mitochondrial cross-section area, mitochondrial perimeter length and increase in mitochondrial number in case of quercetin treated rats as compared to aluminium treated ones. Therefore it seems quercetin increases mitochondrial biogenesis and makes it an almost ideal flavanoid to control or limit the damage that has been associated with the defective mitochondrial function seen in many neurodegenerative diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

Oxaloacetate activates brain mitochondrial biogenesis, enhances the insulin pathway, reduces inflammation and stimulates neurogenesis.

PubMed

Wilkins, Heather M; Harris, Janna L; Carl, Steven M; E, Lezi; Lu, Jianghua; Eva Selfridge, J; Roy, Nairita; Hutfles, Lewis; Koppel, Scott; Morris, Jill; Burns, Jeffrey M; Michaelis, Mary L; Michaelis, Elias K; Brooks, William M; Swerdlow, Russell H

2014-12-15

Brain bioenergetic function declines in some neurodegenerative diseases, this may influence other pathologies and administering bioenergetic intermediates could have therapeutic value. To test how one intermediate, oxaloacetate (OAA) affects brain bioenergetics, insulin signaling, inflammation and neurogenesis, we administered intraperitoneal OAA, 1-2 g/kg once per day for 1-2 weeks, to C57Bl/6 mice. OAA altered levels, distributions or post-translational modifications of mRNA and proteins (proliferator-activated receptor-gamma coactivator 1α, PGC1 related co-activator, nuclear respiratory factor 1, transcription factor A of the mitochondria, cytochrome oxidase subunit 4 isoform 1, cAMP-response element binding, p38 MAPK and adenosine monophosphate-activated protein kinase) in ways that should promote mitochondrial biogenesis. OAA increased Akt, mammalian target of rapamycin and P70S6K phosphorylation. OAA lowered nuclear factor κB nucleus-to-cytoplasm ratios and CCL11 mRNA. Hippocampal vascular endothelial growth factor mRNA, doublecortin mRNA, doublecortin protein, doublecortin-positive neuron counts and neurite length increased in OAA-treated mice. (1)H-MRS showed OAA increased brain lactate, GABA and glutathione thereby demonstrating metabolic changes are detectable in vivo. In mice, OAA promotes brain mitochondrial biogenesis, activates the insulin signaling pathway, reduces neuroinflammation and activates hippocampal neurogenesis. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The effects of exercise and cold exposure on mitochondrial biogenesis in skeletal muscle and white adipose tissue

PubMed Central

Chung, Nana; Park, Jonghoon; Lim, Kiwon

2017-01-01

[Purpose] The purpose of this study was to determine whether exercise or/and cold exposure regulate mitochondria biogenesis-related gene expression in soleus and inguinal adipose tissue of mice. [Methods] Forty ICR 5-week old male mice were divided into four groups: thermoneutrality-untrained (23 ± 1 °C in room temperature, n=10), cold-water immersion (24 ± 1 °C, n=10), exercise in neutral temperature (34 ± 1 °C, n=10), and exercise in cold temperature (24 ± 1 °C, n=10). The mice performed swimming exercise (30 min to 60 min, 5 times) for 8 weeks. After 8 weeks, we confirmed mitochondrial biogenesis-related gene expression changes for peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), nuclear respiratory factors 1 (NRF1), and mitochondrial transcription factor A (Tfam) in soleus muscle and inguinal adipose tissue, and the related protein expression in soleus muscle. [Results] In soleus muscle, PGC-1α expression significantly increased in response to cold exposure (p = 0.006) and exercise (p = 0.05). There was also significant interaction between exercise and cold exposure (p = 0.005). Only exercise had a significant effect on NRF1 relative expression (p=0.001). Neither cold exposure nor the interaction showed significant effects (p = 0.1222 and p = 0.875, respectively). Relative Tfam expression did not show any significant effect from exercise. In inguinal adipose tissue, relative PGC-1α expression did not significantly change in any group. NRF1 expression showed a significant change from exercise (p = 0.01) and cold exposure (p = 0.011). There was also a significant interaction between exercise and cold exposure (p = 0.000). Tfam mRNA expression showed a significant effect from exercise (p=0.000) and an interaction between exercise and cold exposure (p=0.001). Only temperature significantly affected PGC-1α protein levels (p=0.045). Neither exercise nor the interaction were significant (p = 0.397 and p = 0.292, respectively

Adenosine Monophosphate-Activated Protein Kinase Abates Hyperglycaemia-Induced Neuronal Injury in Experimental Models of Diabetic Neuropathy: Effects on Mitochondrial Biogenesis, Autophagy and Neuroinflammation.

PubMed

Yerra, Veera Ganesh; Kumar, Ashutosh

2017-04-01

Impaired adenosine monophosphate kinase (AMPK) signalling under hyperglycaemic conditions is known to cause mitochondrial dysfunction in diabetic sensory neurons. Facilitation of AMPK signalling is previously reported to ameliorate inflammation and induce autophagic response in various complications related to diabetes. The present study assesses the role of AMPK activation on mitochondrial biogenesis, autophagy and neuroinflammation in experimental diabetic neuropathy (DN) using an AMPK activator (A769662). A769662 (15 and 30 mg/kg, i.p) was administered to Sprague-Dawley rats (250-270 g) for 2 weeks after 6 weeks of streptozotocin (STZ) injection (55 mg/kg, i.p.). Behavioural parameters (mechanical/thermal hyperalgesia) and functional characteristics (motor/sensory nerve conduction velocities (MNCV and SNCV) and sciatic nerve blood flow (NBF)) were assessed. For in vitro studies, Neuro2a (N2A) cells were incubated with 25 mM glucose to simulate high glucose condition and then studied for mitochondrial dysfunction and protein expression changes. STZ administration resulted in significant hyperglycaemia (>250 mg/dl) in rats. A769662 treatment significantly improved mechanical/thermal hyperalgesia threshold and enhanced MNCV, SNCV and NBF in diabetic animals. A769662 exposure normalised the mitochondrial superoxide production, membrane depolarisation and markedly increased neurite outgrowth of N2A cells. Further, AMPK activation also abolished the NF-κB-mediated neuroinflammation. A769662 treatment increased Thr-172 phosphorylation of AMPK results in stimulated PGC-1α-directed mitochondrial biogenesis and autophagy induction. Our study supports that compromised AMPK signalling in hyperglycaemic conditions causes defective mitochondrial biogenesis ultimately leading to neuronal dysfunction and associated deficits in DN and activation of AMPK can be developed as an attractive therapeutic strategy for the management of DN.

Effects of Nitric Oxide Synthase Inhibition on Fiber-Type Composition, Mitochondrial Biogenesis, and SIRT1 Expression in Rat Skeletal Muscle

PubMed Central

Suwa, Masataka; Nakano, Hiroshi; Radak, Zsolt; Kumagai, Shuzo

2015-01-01

It was hypothesized that nitric oxide synthases (NOS) regulated SIRT1 expression and lead to a corresponding changes of contractile and metabolic properties in skeletal muscle. The purpose of the present study was to investigate the influence of long-term inhibition of nitric oxide synthases (NOS) on the fiber-type composition, metabolic regulators such as and silent information regulator of transcription 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and components of mitochondrial biogenesis in the soleus and plantaris muscles of rats. Rats were assigned to two groups: control and NOS inhibitor (Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), ingested for 8 weeks in drinking water)-treated groups. The percentage of Type I fibers in the L-NAME group was significantly lower than that in the control group, and the percentage of Type IIA fibers was concomitantly higher in soleus muscle. In plantaris muscle, muscle fiber composition was not altered by L-NAME treatment. L-NAME treatment decreased the cytochrome C protein expression and activity of mitochondrial oxidative enzymes in the plantaris muscle but not in soleus muscle. NOS inhibition reduced the SIRT1 protein expression level in both the soleus and plantaris muscles, whereas it did not affect the PGC-1α protein expression. L-NAME treatment also reduced the glucose transporter 4 protein expression in both muscles. These results suggest that NOS plays a role in maintaining SIRT1 protein expression, muscle fiber composition and components of mitochondrial biogenesis in skeletal muscle. Key points NOS inhibition by L-NAME treatment decreased the SIRT1 protein expression in skeletal muscle. NOS inhibition induced the Type I to Type IIA fiber type transformation in soleus muscle. NOS inhibition reduced the components of mitochondrial biogenesis and glucose metabolism in skeletal muscle. PMID:26336341

Stage of perinatal development regulates skeletal muscle mitochondrial biogenesis and myogenic regulatory factor genes with little impact of growth restriction or cross-fostering.

PubMed

Laker, R C; Wadley, G D; McConell, G K; Wlodek, M E

2012-02-01

Foetal growth restriction impairs skeletal muscle development and adult muscle mitochondrial biogenesis. We hypothesized that key genes involved in muscle development and mitochondrial biogenesis would be altered following uteroplacental insufficiency in rat pups, and improving postnatal nutrition by cross-fostering would ameliorate these deficits. Bilateral uterine vessel ligation (Restricted) or sham (Control) surgery was performed on day 18 of gestation. Males and females were investigated at day 20 of gestation (E20), 1 (PN1), 7 (PN7) and 35 (PN35) days postnatally. A separate cohort of Control and Restricted pups were cross-fostered onto a different Control or Restricted mother and examined at PN7. In both sexes, peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), cytochrome c oxidase subunits 3 and 4 (COX III and IV) and myogenic regulatory factor 4 expression increased from late gestation to postnatal life, whereas mitochondrial transcription factor A, myogenic differentiation 1 (MyoD), myogenin and insulin-like growth factor I (IGF-I) decreased. Foetal growth restriction increased MyoD mRNA in females at PN7, whereas in males IGF-I mRNA was higher at E20 and PN1. Cross-fostering Restricted pups onto a Control mother significantly increased COX III mRNA in males and COX IV mRNA in both sexes above controls with little effect on other genes. Developmental age appears to be a major factor regulating skeletal muscle mitochondrial and developmental genes, with growth restriction and cross-fostering having only subtle effects. It therefore appears that reductions in adult mitochondrial biogenesis markers likely develop after weaning.

A novel mitochondrial orf147 causes cytoplasmic male sterility in pigeonpea by modulating aberrant anther dehiscence.

PubMed

Bhatnagar-Mathur, Pooja; Gupta, Ranadheer; Reddy, Palakolanu Sudhakar; Reddy, Bommineni Pradeep; Reddy, Dumbala Srinivas; Sameerkumar, C V; Saxena, Rachit Kumar; Sharma, Kiran K

2018-05-01

A novel open reading frame (ORF) identified and cloned from the A4 cytoplasm of Cajanus cajanifolius induced partial to complete male sterility when introduced into Arabidopsis and tobacco. Pigeonpea (Cajanus cajan L. Millsp.) is the only legume known to have commercial hybrid seed technology based on cytoplasmic male sterility (CMS). We identified a novel ORF (orf147) from the A4 cytoplasm of C. cajanifolius that was created via rearrangements in the CMS line and co-transcribes with the known and unknown sequences. The bi/poly-cistronic transcripts cause gain-of-function variants in the mitochondrial genome of CMS pigeonpea lines having distinct processing mechanisms and transcription start sites. In presence of orf147, significant repression of Escherichia coli growth indicated its toxicity to the host cells and induced partial to complete male sterility in transgenic progenies of Arabidopsis thaliana and Nicotiana tabacum where phenotype co-segregated with the transgene. The male sterile plants showed aberrant floral development and reduced lignin content in the anthers. Gene expression studies in male sterile pigeonpea, Arabidopsis and tobacco plants confirmed down-regulation of several anther biogenesis genes and key genes involved in monolignol biosynthesis, indicative of regulation of retrograde signaling. Besides providing evidence for the involvement of orf147 in pigeonpea CMS, this study provides valuable insights into its function. Cytotoxicity and aberrant programmed cell death induced by orf147 could be important for mechanism underlying male sterility that offers opportunities for possible translation for these findings for exploiting hybrid vigor in other recalcitrant crops as well.

Nicotinamide Riboside and Mitochondrial Biogenesis

ClinicalTrials.gov

2018-03-15

Mitochondrial Diseases; Mitochondrial Myopathies; Progressive External Ophthalmoplegia; Progressive Ophthalmoplegia; Progressive; Ophthalmoplegia, External; Mitochondria DNA Deletion; MELAS; Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes; Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-Like Episodes (MELAS Syndrome)

A Time to Reap, a Time to Sow: Mitophagy and Biogenesis in Cardiac Pathophysiology

PubMed Central

Andres, Allen M.; Stotland, Aleksandr; Queliconi, Bruno B.; Gottlieb, Roberta A.

2014-01-01

Balancing mitophagy and mitochondrial biogenesis is essential for maintaining a healthy population of mitochondria and cellular homeostasis. Coordinated interplay between these two forces that govern mitochondrial turnover plays an important role as an adaptive response against various cellular stresses that can compromise cell survival. Failure to maintain the critical balance between mitophagy and mitochondrial biogenesis or homeostatic turnover of mitochondria results in a population of dysfunctional mitochondria that contribute to various disease processes. In this review we outline the mechanics and relationships between mitophagy and mitochondrial biogenesis, and discuss the implications of a disrupted balance between these two forces, with an emphasis on cardiac physiology. PMID:25444712

Sirtuin 3, a New Target of PGC-1α, Plays an Important Role in the Suppression of ROS and Mitochondrial Biogenesis

PubMed Central

Kong, Xingxing; Wang, Rui; Xue, Yuan; Liu, Xiaojun; Zhang, Huabing; Chen, Yong; Fang, Fude; Chang, Yongsheng

2010-01-01

Background Sirtuin 3 (SIRT3) is one of the seven mammalian sirtuins, which are homologs of the yeast Sir2 gene. SIRT3 is the only sirtuin with a reported association with the human life span. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) plays important roles in adaptive thermogenesis, gluconeogenesis, mitochondrial biogenesis and respiration. PGC-1α induces several key reactive oxygen species (ROS)-detoxifying enzymes, but the molecular mechanism underlying this is not well understood. Results Here we show that PGC-1α strongly stimulated mouse Sirt3 gene expression in muscle cells and hepatocytes. Knockdown of PGC-1α led to decreased Sirt3 gene expression. PGC-1α activated the mouse SIRT3 promoter, which was mediated by an estrogen-related receptor (ERR) binding element (ERRE) (−407/−399) mapped to the promoter region. Chromatin immunoprecipitation and electrophoretic mobility shift assays confirmed that ERRα bound to the identified ERRE and PGC-1α co-localized with ERRα in the mSirt3 promoter. Knockdown of ERRα reduced the induction of Sirt3 by PGC-1α in C2C12 myotubes. Furthermore, Sirt3 was essential for PGC-1α-dependent induction of ROS-detoxifying enzymes and several components of the respiratory chain, including glutathione peroxidase-1, superoxide dismutase 2, ATP synthase 5c, and cytochrome c. Overexpression of SIRT3 or PGC-1α in C2C12 myotubes decreased basal ROS level. In contrast, knockdown of mSIRT3 increased basal ROS level and blocked the inhibitory effect of PGC-1α on cellular ROS production. Finally, SIRT3 stimulated mitochondrial biogenesis, and SIRT3 knockdown decreased the stimulatory effect of PGC-1α on mitochondrial biogenesis in C2C12 myotubes. Conclusion Our results indicate that Sirt3 functions as a downstream target gene of PGC-1α and mediates the PGC-1α effects on cellular ROS production and mitochondrial biogenesis. Thus, SIRT3 integrates cellular energy metabolism and ROS generation. The

Disrupted Skeletal Muscle Mitochondrial Dynamics, Mitophagy, and Biogenesis during Cancer Cachexia: A Role for Inflammation

PubMed Central

VanderVeen, Brandon N.; Fix, Dennis K.

2017-01-01

Chronic inflammation is a hallmark of cancer cachexia in both patients and preclinical models. Cachexia is prevalent in roughly 80% of cancer patients and accounts for up to 20% of all cancer-related deaths. Proinflammatory cytokines IL-6, TNF-α, and TGF-β have been widely examined for their regulation of cancer cachexia. An established characteristic of cachectic skeletal muscle is a disrupted capacity for oxidative metabolism, which is thought to contribute to cancer patient fatigue, diminished metabolic function, and muscle mass loss. This review's primary objective is to highlight emerging evidence linking cancer-induced inflammation to the dysfunctional regulation of mitochondrial dynamics, mitophagy, and biogenesis in cachectic muscle. The potential for either muscle inactivity or exercise to alter mitochondrial dysfunction during cancer cachexia will also be discussed. PMID:28785374

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

PubMed

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

2018-05-01

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

Exercise Prevents Cardiac Injury and Improves Mitochondrial Biogenesis in Advanced Diabetic Cardiomyopathy with PGC-1α and Akt Activation.

PubMed

Wang, Hui; Bei, Yihua; Lu, Yan; Sun, Wei; Liu, Qi; Wang, Yalong; Cao, Yujie; Chen, Ping; Xiao, Junjie; Kong, Xiangqing

2015-01-01

Diabetic cardiomyopathy (DCM) represents the major cause of morbidity and mortality among diabetics. Exercise has been reported to be effective to protect the heart from cardiac injury during the development of DCM. However, the potential cardioprotective effect of exercise in advanced DCM remains unclear. Seven-week old male C57BL/6 wild-type or db/db mice were either subjected to a running exercise program for 15 weeks or kept sedentary. Cardiac function, myocardial apoptosis and fibrosis, and mitochondrial biogenesis were examined for evaluation of cardiac injury. A reduction in ejection fraction and fractional shortening in db/db mice was significantly reversed by exercise training. DCM induced remarkable cardiomyocyte apoptosis and increased ratio of Bax/Bcl-2 at the protein level. Meanwhile, DCM caused slightly myocardial fibrosis with elevated mRNA levels of collagen I and collagen III. Also, DCM resulted in a reduction of mitochondrial DNA (mtDNA) replication and transcription, together with reduced mtDNA content and impaired mitochondrial ultrastructure. All of these changes could be abolished by exercise training. Furthermore, DCM-associated inhibition of PGC-1α and Akt signaling was significantly activated by exercise, indicating that exercise-induced activation of PGC-1α and Akt signaling might be responsible for mediating cardioprotective effect of exercise in DCM. Exercise preserves cardiac function, prevents myocardial apoptosis and fibrosis, and improves mitochondrial biogenesis in the late stage of DCM. Exercise-induced activation of PGC-1α and Akt signaling might be promising therapeutic targets for advanced DCM. © 2015 S. Karger AG, Basel.

Effect of dietary resveratrol supplementation on meat quality, muscle antioxidative capacity and mitochondrial biogenesis of broilers.

PubMed

Zhang, Cheng; Yang, Lei; Zhao, Xiaohui; Chen, Xingyong; Wang, Li; Geng, Zhaoyu

2018-02-01

The naturally occurring polyphenol resveratrol has been acknowledged with many beneficial biological effects. The aim of this study was to evaluate the influence of dietary resveratrol supplementation on meat quality, muscle antioxidative capacity and mitochondrial biogenesis of broilers. One hundred and eighty 21-day-old male Cobb broilers were randomly assigned to two groups and fed on a 0 mg kg -1 or 400 mg kg -1 resveratrol-supplemented diet for 21 days. Then, chickens were slaughtered and pectoralis major muscle (PM) samples were collected for analysis. The results showed that resveratrol not only tended to increase (P < 0.10) PM pH 24h but also significantly decreased (P < 0.05) PM L* 45min , pH decline, drip loss and lactate content. Meanwhile, PM total antioxidative capacity and catalase activity were significantly increased (P < 0.05) by resveratrol, while malondialdehyde content was decreased (P < 0.10). Moreover, resveratrol significantly increased (P < 0.05) PM peroxisome proliferator-activated receptor γ coactivator 1α and nuclear respiratory factor 1 mRNA levels, along with increased (P < 0.05) citrate synthase activity. Resveratrol can be used as a feed additive to improve meat quality of broilers, which may be associated with improved muscle antioxidative status and mitochondrial biogenesis. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Sam37 is crucial for formation of the mitochondrial TOM-SAM supercomplex, thereby promoting β-barrel biogenesis.

PubMed

Wenz, Lena-Sophie; Ellenrieder, Lars; Qiu, Jian; Bohnert, Maria; Zufall, Nicole; van der Laan, Martin; Pfanner, Nikolaus; Wiedemann, Nils; Becker, Thomas

2015-09-28

Biogenesis of mitochondrial β-barrel proteins requires two preprotein translocases, the general translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). TOM and SAM form a supercomplex that promotes transfer of β-barrel precursors. The SAM core complex contains the channel protein Sam50, which cooperates with Sam35 in precursor recognition, and the peripheral membrane protein Sam37. The molecular function of Sam37 has been unknown. We report that Sam37 is crucial for formation of the TOM-SAM supercomplex. Sam37 interacts with the receptor domain of Tom22 on the cytosolic side of the mitochondrial outer membrane and links TOM and SAM complexes. Sam37 thus promotes efficient transfer of β-barrel precursors to the SAM complex. We conclude that Sam37 functions as a coupling factor of the translocase supercomplex of the mitochondrial outer membrane. © 2015 Wenz et al.

Idiopathic chronic fatigue in older adults is linked to impaired mitochondrial content and biogenesis signaling in skeletal muscle.

PubMed

Wawrzyniak, Nicholas R; Joseph, Anna-Maria; Levin, David G; Gundermann, David M; Leeuwenburgh, Christiaan; Sandesara, Bhanuprasad; Manini, Todd M; Adhihetty, Peter J

2016-08-16

Fatigue is a symptom of many diseases, but it can also manifest as a unique medical condition, such as idiopathic chronic fatigue (ICF). While the prevalence of ICF increases with age, mitochondrial content and function decline with age, which may contribute to ICF. The purpose of this study was to determine whether skeletal muscle mitochondrial dysregulation and oxidative stress is linked to ICF in older adults. Sedentary, old adults (n = 48, age 72.4 ± 5.3 years) were categorized into ICF and non-fatigued (NF) groups based on the FACIT-Fatigue questionnaire. ICF individuals had a FACIT score one standard deviation below the mean for non-anemic adults > 65 years and were excluded according to CDC diagnostic criteria for ICF. Vastus lateralis muscle biopsies were analyzed, showing reductions in mitochondrial content and suppression of mitochondrial regulatory proteins Sirt3, PGC-1α, NRF-1, and cytochrome c in ICF compared to NF. Additionally, mitochondrial morphology proteins, antioxidant enzymes, and lipid peroxidation were unchanged in ICF individuals. Our data suggests older adults with ICF have reduced skeletal muscle mitochondrial content and biogenesis signaling that cannot be accounted for by increased oxidative damage.

Mitochondrial Biogenesis in Diverse Cauliflower Cultivars under Mild and Severe Drought. Impaired Coordination of Selected Transcript and Proteomic Responses, and Regulation of Various Multifunctional Proteins

PubMed Central

Rurek, Michał; Czołpińska, Magdalena; Staszak, Aleksandra Maria; Nowak, Witold; Krzesiński, Włodzimierz; Spiżewski, Tomasz

2018-01-01

Mitochondrial responses under drought within Brassica genus are poorly understood. The main goal of this study was to investigate mitochondrial biogenesis of three cauliflower (Brassica oleracea var. botrytis) cultivars with varying drought tolerance. Diverse quantitative changes (decreases in abundance mostly) in the mitochondrial proteome were assessed by two-dimensional gel electrophoresis (2D PAGE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Respiratory (e.g., complex II, IV (CII, CIV) and ATP synthase subunits), transporter (including diverse porin isoforms) and matrix multifunctional proteins (e.g., components of RNA editing machinery) were diversely affected in their abundance under two drought levels. Western immunoassays showed additional cultivar-specific responses of selected mitochondrial proteins. Dehydrin-related tryptic peptides (found in several 2D spots) immunopositive with dehydrin-specific antisera highlighted the relevance of mitochondrial dehydrin-like proteins for the drought response. The abundance of selected mRNAs participating in drought response was also determined. We conclude that mitochondrial biogenesis was strongly, but diversely affected in various cauliflower cultivars, and associated with drought tolerance at the proteomic and functional levels. However, discussed alternative oxidase (AOX) regulation at the RNA and protein level were largely uncoordinated due to the altered availability of transcripts for translation, mRNA/ribosome interactions, and/or miRNA impact on transcript abundance and translation. PMID:29642585

p21{sup WAF1/CIP1} deficiency induces mitochondrial dysfunction in HCT116 colon cancer cells

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

Kim, Ae Jeong; Jee, Hye Jin; Song, Naree

2013-01-11

Highlights: Black-Right-Pointing-Pointer p21{sup -/-} HCT116 cells exhibited an increase in mitochondrial mass. Black-Right-Pointing-Pointer The expression levels of PGC-1{alpha} and AMPK were upregulated in p21{sup -/-} HCT116 cells. Black-Right-Pointing-Pointer The proliferation of p21{sup -/-} HCT116 cells in galactose medium was significantly impaired. Black-Right-Pointing-Pointer p21 may play a role in maintaining proper mitochondrial mass and respiratory function. -- Abstract: p21{sup WAF1/CIP1} is a critical regulator of cell cycle progression. However, the role of p21 in mitochondrial function remains poorly understood. In this study, we examined the effect of p21 deficiency on mitochondrial function in HCT116 human colon cancer cells. We found thatmore » there was a significant increase in the mitochondrial mass of p21{sup -/-} HCT116 cells, as measured by 10-N-nonyl-acridine orange staining, as well as an increase in the mitochondrial DNA content. In contrast, p53{sup -/-} cells had a mitochondrial mass comparable to that of wild-type HCT116 cells. In addition, the expression levels of the mitochondrial biogenesis regulators PGC-1{alpha} and TFAM and AMPK activity were also elevated in p21{sup -/-} cells, indicating that p21 deficiency induces the rate of mitochondrial biogenesis through the AMPK-PGC-1{alpha} axis. However, the increase in mitochondrial biogenesis in p21{sup -/-} cells did not accompany an increase in the cellular steady-state level of ATP. Furthermore, p21{sup -/-} cells exhibited significant proliferation impairment in galactose medium, suggesting that p21 deficiency induces a defect in the mitochondrial respiratory chain in HCT116 cells. Taken together, our results suggest that the loss of p21 results in an aberrant increase in the mitochondrial mass and in mitochondrial dysfunction in HCT116 cells, indicating that p21 is required to maintain proper mitochondrial mass and respiratory function.« less

The Forkhead Transcription Factor Hcm1 Promotes Mitochondrial Biogenesis and Stress Resistance in Yeast*

PubMed Central

Rodriguez-Colman, Maria José; Reverter-Branchat, Gemma; Sorolla, M. Alba; Tamarit, Jordi; Ros, Joaquim; Cabiscol, Elisa

2010-01-01

In Saccharomyces cerevisiae, the forkhead transcription factor Hcm1 is involved in chromosome segregation, spindle pole dynamics, and budding. We found that Hcm1 interacts with the histone deacetylase Sir2 and shifts from cytoplasm to the nucleus in the G1/S phase or in response to oxidative stress stimuli. The nuclear localization of Hcm1 depends on the activity of Sir2 as revealed by activators and inhibitors of the sirtuins and the Δsir2 mutant. Hcm1-overexpressing cells display more mitochondria that can be attributed to increased amounts of Abf2, a protein involved in mitochondrial biogenesis. These cells also show higher rates of oxygen consumption and improved resistance to oxidative stress that would be explained by increased catalase and Sod2 activities and molecular chaperones such as Hsp26, Hsp30, and members of Hsp70 family. Microarray analyses also reveal increased expression of genes involved in mitochondrial energy pathways and those allowing the transition from the exponential to the stationary phase. Taken together, these results describe a new and relevant role of Hcm1 for mitochondrial functions, suggesting that this transcription factor would participate in the adaptation of cells from fermentative to respiratory metabolism. PMID:20847055

Human Cytomegalovirus Infection Upregulates the Mitochondrial Transcription and Translation Machineries

PubMed Central

Weekes, M. P.; Antrobus, R.; Rorbach, J.; van Haute, L.; Umrania, Y.; Smith, D. L.; Minczuk, M.; Lehner, P. J.; Sinclair, J. H.

2016-01-01

ABSTRACT Infection with human cytomegalovirus (HCMV) profoundly affects cellular metabolism. Like in tumor cells, HCMV infection increases glycolysis, and glucose carbon is shifted from the mitochondrial tricarboxylic acid cycle to the biosynthesis of fatty acids. However, unlike in many tumor cells, where aerobic glycolysis is accompanied by suppression of mitochondrial oxidative phosphorylation, HCMV induces mitochondrial biogenesis and respiration. Here, we affinity purified mitochondria and used quantitative mass spectrometry to determine how the mitochondrial proteome changes upon HCMV infection. We found that the mitochondrial transcription and translation systems are induced early during the viral replication cycle. Specifically, proteins involved in biogenesis of the mitochondrial ribosome were highly upregulated by HCMV infection. Inhibition of mitochondrial translation with chloramphenicol or knockdown of HCMV-induced ribosome biogenesis factor MRM3 abolished the HCMV-mediated increase in mitochondrially encoded proteins and significantly impaired viral growth under bioenergetically restricting conditions. Our findings demonstrate how HCMV manipulates mitochondrial biogenesis to support its replication. PMID:27025248

Aluminium induced oxidative stress results in decreased mitochondrial biogenesis via modulation of PGC-1α expression.

PubMed

Sharma, Deep Raj; Sunkaria, Aditya; Wani, Willayat Yousuf; Sharma, Reeta Kumari; Kandimalla, Ramesh J L; Bal, Amanjit; Gill, Kiran Dip

2013-12-01

The present investigation was carried out to elucidate a possible molecular mechanism related to the effects of aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of Peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α) and its downstream targets i.e. Nuclear respiratory factor-1(NRF-1), Nuclear respiratory factor-2(NRF-2) and Mitochondrial transcription factor A (Tfam) in mitochondrial biogenesis. Aluminium lactate (10mg/kgb.wt./day) was administered intragastrically to rats for 12 weeks. After 12 weeks of exposure, we found an increase in ROS levels, mitochondrial DNA oxidation and decrease in citrate synthase activity in the Hippocampus (HC) and Corpus striatum (CS) regions of rat brain. On the other hand, there was a decrease in the mRNA levels of the mitochondrial encoded subunits-NADH dehydrogenase (ND) subunits i.e. ND1, ND2, ND3, Cytochrome b (Cytb), Cytochrome oxidase (COX) subunits i.e. COX1, COX3, ATP synthase (ATPase) subunit 6 along with reduced expression of nuclear encoded subunits COX4, COX5A, COX5B of Electron transport chain (ETC). Besides, a decrease in mitochondrial DNA copy number and mitochondrial content in both regions of rat brain was observed. The PGC-1α was down-regulated in aluminium treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α in aluminium treated rats. Electron microscopy results revealed a significant increase in the mitochondrial swelling, loss of cristae, chromatin condensation and decreases in mitochondrial number in case of aluminium treated rats as compared to control. So, PGC-1α seems to be a potent target for aluminium neurotoxicity, which makes it an almost ideal target to control or limit the damage that has been associated with the defective mitochondrial function seen in neurodegenerative diseases. © 2013.

Mitochondrial gene therapy improves respiration, biogenesis, and transcription in G11778A Leber's hereditary optic neuropathy and T8993G Leigh's syndrome cells.

PubMed

Iyer, Shilpa; Bergquist, Kristen; Young, Kisha; Gnaiger, Erich; Rao, Raj R; Bennett, James P

2012-06-01

Many incurable mitochondrial disorders result from mutant mitochondrial DNA (mtDNA) and impaired respiration. Leigh's syndrome (LS) is a fatal neurodegenerative disorder of infants, and Leber's hereditary optic neuropathy (LHON) causes blindness in young adults. Treatment of LHON and LS cells harboring G11778A and T8993G mutant mtDNA, respectively, by >90%, with healthy donor mtDNA complexed with recombinant human mitochondrial transcription factor A (rhTFAM), improved mitochondrial respiration by ∼1.2-fold in LHON cells and restored >50% ATP synthase function in LS cells. Mitochondrial replication, transcription, and translation of key respiratory genes and proteins were increased in the short term. Increased NRF1, TFAMB1, and TFAMA expression alluded to the activation of mitochondrial biogenesis as a mechanism for improving mitochondrial respiration. These results represent the development of a therapeutic approach for LHON and LS patients in the near future.

Maturation of the unusual single-cysteine (XXXCH) mitochondrial c-type cytochromes found in trypanosomatids must occur through a novel biogenesis pathway

PubMed Central

Allen, James W. A.; Ginger, Michael L.; Ferguson, Stuart J.

2004-01-01

The c-type cytochromes are characterized by the covalent attachment of haem to the polypeptide via thioether bonds formed from haem vinyl groups and, normally, the thiols of two cysteines in a CXXCH motif. Intriguingly, the mitochondrial cytochromes c and c1 from two euglenids and the Trypanosomatidae contain only a single cysteine within the haem-binding motif (XXXCH). There are three known distinct pathways by which c-type cytochromes are matured post-translationally in different organisms. The absence of genes encoding any of these c-type cytochrome biogenesis machineries is established here by analysis of six trypanosomatid genomes, and correlates with the presence of single-cysteine cytochromes c and c1. In contrast, we have identified a comprehensive catalogue of proteins required for a typical mitochondrial oxidative phosphorylation apparatus. Neither spontaneous nor catalysed maturation of the single-cysteine Trypanosoma brucei cytochrome c occurred in Escherichia coli. However, a CXXCH variant was matured by the E. coli cytochrome c maturation machinery, confirming the proposed requirement of the latter for two cysteines in the haem-binding motif and indicating that T. brucei cytochrome c can accommodate a second cysteine in a CXXCH motif. The single-cysteine haem attachment conserved in cytochromes c and c1 of the trypanosomatids is suggested to be related to their cytochrome c maturation machinery, and the environment in the mitochondrial intermembrane space. Our genomic and biochemical studies provide very persuasive evidence that the trypanosomatid mitochondrial cytochromes c are matured by a novel biogenesis system. PMID:15500440

Decreased endothelial nitric oxide synthase expression and function contribute to impaired mitochondrial biogenesis and oxidative stress in fetal lambs with persistent pulmonary hypertension.

PubMed

Afolayan, Adeleye J; Eis, Annie; Alexander, Maxwell; Michalkiewicz, Teresa; Teng, Ru-Jeng; Lakshminrusimha, Satyan; Konduri, Girija G

2016-01-01

Impaired vasodilation in persistent pulmonary hypertension of the newborn (PPHN) is characterized by mitochondrial dysfunction. We investigated the hypothesis that a decreased endothelial nitric oxide synthase level leads to impaired mitochondrial biogenesis and function in a lamb model of PPHN induced by prenatal ductus arteriosus constriction. We ventilated PPHN lambs with 100% O2 alone or with inhaled nitric oxide (iNO). We treated pulmonary artery endothelial cells (PAECs) from normal and PPHN lambs with detaNONOate, an NO donor. We observed decreased mitochondrial (mt) DNA copy number, electron transport chain (ETC) complex subunit levels, and ATP levels in PAECs and lung tissue of PPHN fetal lambs at baseline compared with gestation matched controls. Phosphorylation of AMP-activated kinase (AMPK) and levels of peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α) and sirtuin-1, which facilitate mitochondrial biogenesis, were decreased in PPHN. Ventilation with 100% O2 was associated with larger decreases in ETC subunits in the lungs of PPHN lambs compared with unventilated PPHN lambs. iNO administration, which facilitated weaning of FiO2 , partly restored mtDNA copy number, ETC subunit levels, and ATP levels. DetaNONOate increased eNOS phosphorylation and its interaction with heat shock protein 90 (HSP90); increased levels of superoxide dismutase 2 (SOD2) mRNA, protein, and activity; and decreased the mitochondrial superoxide levels in PPHN-PAECs. Knockdown of eNOS decreased ETC protein levels in control PAECs. We conclude that ventilation with 100% O2 amplifies oxidative stress and mitochondrial dysfunction in PPHN, which are partly improved by iNO and weaning of oxygen. Copyright © 2016 the American Physiological Society.

Multi-focal control of mitochondrial gene expression by oncogenic MYC provides potential therapeutic targets in cancer

PubMed Central

Oran, Amanda R.; Adams, Clare M.; Zhang, Xiao-yong; Gennaro, Victoria J.; Pfeiffer, Harla K.; Mellert, Hestia S.; Seidel, Hans E.; Mascioli, Kirsten; Kaplan, Jordan; Gaballa, Mahmoud R.; Shen, Chen; Rigoutsos, Isidore; King, Michael P.; Cotney, Justin L.; Arnold, Jamie J.; Sharma, Suresh D.; Martinez, Ubaldo E.; Vakoc, Christopher R.; Chodosh, Lewis A.; Thompson, James E.; Bradner, James E.; Cameron, Craig E.; Shadel, Gerald S.; Eischen, Christine M.; McMahon, Steven B.

2016-01-01

Despite ubiquitous activation in human cancer, essential downstream effector pathways of the MYC transcription factor have been difficult to define and target. Using a structure/function-based approach, we identified the mitochondrial RNA polymerase (POLRMT) locus as a critical downstream target of MYC. The multifunctional POLRMT enzyme controls mitochondrial gene expression, a process required both for mitochondrial function and mitochondrial biogenesis. We further demonstrate that inhibition of this newly defined MYC effector pathway causes robust and selective tumor cell apoptosis, via an acute, checkpoint-like mechanism linked to aberrant electron transport chain complex assembly and mitochondrial reactive oxygen species (ROS) production. Fortuitously, MYC-dependent tumor cell death can be induced by inhibiting the mitochondrial gene expression pathway using a variety of strategies, including treatment with FDA-approved antibiotics. In vivo studies using a mouse model of Burkitt's Lymphoma provide pre-clinical evidence that these antibiotics can successfully block progression of MYC-dependent tumors. PMID:27590350

Multi-focal control of mitochondrial gene expression by oncogenic MYC provides potential therapeutic targets in cancer.

PubMed

Oran, Amanda R; Adams, Clare M; Zhang, Xiao-Yong; Gennaro, Victoria J; Pfeiffer, Harla K; Mellert, Hestia S; Seidel, Hans E; Mascioli, Kirsten; Kaplan, Jordan; Gaballa, Mahmoud R; Shen, Chen; Rigoutsos, Isidore; King, Michael P; Cotney, Justin L; Arnold, Jamie J; Sharma, Suresh D; Martinez-Outschoorn, Ubaldo E; Vakoc, Christopher R; Chodosh, Lewis A; Thompson, James E; Bradner, James E; Cameron, Craig E; Shadel, Gerald S; Eischen, Christine M; McMahon, Steven B

2016-11-08

Despite ubiquitous activation in human cancer, essential downstream effector pathways of the MYC transcription factor have been difficult to define and target. Using a structure/function-based approach, we identified the mitochondrial RNA polymerase (POLRMT) locus as a critical downstream target of MYC. The multifunctional POLRMT enzyme controls mitochondrial gene expression, a process required both for mitochondrial function and mitochondrial biogenesis. We further demonstrate that inhibition of this newly defined MYC effector pathway causes robust and selective tumor cell apoptosis, via an acute, checkpoint-like mechanism linked to aberrant electron transport chain complex assembly and mitochondrial reactive oxygen species (ROS) production. Fortuitously, MYC-dependent tumor cell death can be induced by inhibiting the mitochondrial gene expression pathway using a variety of strategies, including treatment with FDA-approved antibiotics. In vivo studies using a mouse model of Burkitt's Lymphoma provide pre-clinical evidence that these antibiotics can successfully block progression of MYC-dependent tumors.

Inflexibility of AMPK-mediated metabolic reprogramming in mitochondrial disease

PubMed Central

Lin, Dar-Shong; Kao, Shu-Huei; Ho, Che-Sheng; Wei, Yau-Huei; Hung, Pi-Lien; Hsu, Mei-Hsin; Wu, Tsu-Yen; Wang, Tuan-Jen; Jian, Yuan-Ren; Lee, Tsung-Han; Chiang, Ming-Fu

2017-01-01

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is most commonly caused by the A3243G mutation of mitochondrial DNA. The capacity to utilize fatty acid or glucose as a fuel source and how such dynamic switches of metabolic fuel preferences and transcriptional modulation of adaptive mechanism in response to energy deficiency in MELAS syndrome have not been fully elucidated. The fibroblasts from patients with MELAS syndrome demonstrated a remarkable deficiency of electron transport chain complexes I and IV, an impaired cellular biogenesis under glucose deprivation, and a decreased ATP synthesis. In situ analysis of the bioenergetic properties of MELAS cells demonstrated an attenuated fatty acid oxidation that concomitantly occurred with impaired mitochondrial respiration, while energy production was mostly dependent on glycolysis. Furthermore, the transcriptional modulation was mediated by the AMP-activated protein kinase (AMPK) signaling pathway, which activated its downstream modulators leading to a subsequent increase in glycolytic flux through activation of pyruvate dehydrogenase. In contrast, the activities of carnitine palmitoyltransferase for fatty acid oxidation and acetyl-CoA carboxylase-1 for fatty acid synthesis were reduced and transcriptional regulation factors for biogenesis were not altered. These results provide novel information that MELAS cells lack the adaptive mechanism to switch fuel source from glucose to fatty acid, as glycolysis rates increase in response to energy deficiency. The aberrant secondary cellular responses to disrupted metabolic homeostasis mediated by AMPK signaling pathway may contribute to the development of the clinical phenotype. PMID:29088732

Promoting PGC-1α-driven mitochondrial biogenesis is detrimental in pressure-overloaded mouse hearts

PubMed Central

Karamanlidis, Georgios; Garcia-Menendez, Lorena; Kolwicz, Stephen C.; Lee, Chi Fung

2014-01-01

Mitochondrial dysfunction in animal models of heart failure is associated with downregulation of the peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α pathway. To test whether PGC-1α is an appropriate therapeutic target for increasing mitochondrial biogenesis and improving function in heart failure, we used a transgenic (TG) mouse model of moderate overexpression of PGC-1α (∼3-fold) in the heart. TG mice had small increases in citrate synthase activity and mitochondria size in the heart without alterations in myocardial energetics or cardiac function at baseline. In vivo dobutamine stress increased fractional shortening in wild-type mice, but this increase was attenuated in TG mice, whereas ex vivo isolated perfused TG hearts demonstrated normal functional and energetic response to high workload challenge. When subjected to pressure overload by transverse aortic constriction (TAC), TG mice displayed a significantly greater acute mortality for both male and female mice; however, long-term survival up to 8 wk was similar between the two groups. TG mice also showed a greater decrease in fractional shortening and a greater increase in left ventricular chamber dimension in response to TAC. Mitochondrial gene expression and citrate synthase activity were mildly increased in TG mice compared with wild-type mice, and this difference was also maintained after TAC. Our data suggest that a moderate level of PGC-1α overexpression in the heart compromises acute survival and does not improve cardiac function during chronic pressure overload in mice. PMID:25172896

Aluminium induced oxidative stress results in decreased mitochondrial biogenesis via modulation of PGC-1α expression

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

Sharma, Deep Raj; Sunkaria, Aditya; Wani, Willayat Yousuf

The present investigation was carried out to elucidate a possible molecular mechanism related to the effects of aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of Peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α) and its downstream targets i.e. Nuclear respiratory factor-1(NRF-1), Nuclear respiratory factor-2(NRF-2) and Mitochondrial transcription factor A (Tfam) in mitochondrial biogenesis. Aluminium lactate (10 mg/kg b.wt./day) was administered intragastrically to rats for 12 weeks. After 12 weeks of exposure, we found an increase in ROS levels, mitochondrial DNA oxidation and decrease in citrate synthase activity in the Hippocampus (HC) andmore » Corpus striatum (CS) regions of rat brain. On the other hand, there was a decrease in the mRNA levels of the mitochondrial encoded subunits–NADH dehydrogenase (ND) subunits i.e. ND1, ND2, ND3, Cytochrome b (Cytb), Cytochrome oxidase (COX) subunits i.e. COX1, COX3, ATP synthase (ATPase) subunit 6 along with reduced expression of nuclear encoded subunits COX4, COX5A, COX5B of Electron transport chain (ETC). Besides, a decrease in mitochondrial DNA copy number and mitochondrial content in both regions of rat brain was observed. The PGC-1α was down-regulated in aluminium treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α in aluminium treated rats. Electron microscopy results revealed a significant increase in the mitochondrial swelling, loss of cristae, chromatin condensation and decreases in mitochondrial number in case of aluminium treated rats as compared to control. So, PGC-1α seems to be a potent target for aluminium neurotoxicity, which makes it an almost ideal target to control or limit the damage that has been associated with the defective mitochondrial function seen in neurodegenerative diseases. - Highlights: • Aluminium decreases the mRNA levels of mitochondrial and nuclear

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis

PubMed Central

Boulet, Aren; Vest, Katherine E.; Maynard, Margaret K.; Gammon, Micah G.; Russell, Antoinette C.; Mathews, Alexander T.; Cole, Shelbie E.; Zhu, Xinyu; Phillips, Casey B.; Kwong, Jennifer Q.; Dodani, Sheel C.; Leary, Scot C.; Cobine, Paul A.

2018-01-01

Copper is required for the activity of cytochrome c oxidase (COX), the terminal electron-accepting complex of the mitochondrial respiratory chain. The likely source of copper used for COX biogenesis is a labile pool found in the mitochondrial matrix. In mammals, the proteins that transport copper across the inner mitochondrial membrane remain unknown. We previously reported that the mitochondrial carrier family protein Pic2 in budding yeast is a copper importer. The closest Pic2 ortholog in mammalian cells is the mitochondrial phosphate carrier SLC25A3. Here, to investigate whether SLC25A3 also transports copper, we manipulated its expression in several murine and human cell lines. SLC25A3 knockdown or deletion consistently resulted in an isolated COX deficiency in these cells, and copper addition to the culture medium suppressed these biochemical defects. Consistent with a conserved role for SLC25A3 in copper transport, its heterologous expression in yeast complemented copper-specific defects observed upon deletion of PIC2. Additionally, assays in Lactococcus lactis and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both in vitro and in vivo. PMID:29237729

Mitochondrial dynamics and Parkinson's disease: focus on parkin.

PubMed

Lim, Kah-Leong; Ng, Xiao-Hui; Grace, Lim Gui-Yin; Yao, Tso-Pang

2012-05-01

Parkinson's disease (PD) is a prevalent neurodegenerative disease affecting millions of individuals worldwide. Despite intensive efforts devoted to drug discovery, the disease remains incurable. To provide more effective medical therapy for PD, better understanding of the underlying causes of the disease is clearly necessary. A broad range of studies conducted over the past few decades have collectively implicated aberrant mitochondrial homeostasis as a key contributor to the development of PD. Supporting this, mutations in several PD-linked genes are directly or indirectly linked to mitochondrial dysfunction. In particular, recent discoveries have identified parkin, whose mutations are causative of recessive parkinsonism, as a key regulator of mitochondrial homeostasis. Parkin appears to be involved in the entire spectrum of mitochondrial dynamics, including organelle biogenesis, fusion/fission, and clearance via mitophagy. How a single protein can regulate such diverse mitochondrial events is as intriguing as it is amazing; the mechanism underlying this is currently under intense research. Here, we provide an overview of mitochondrial dynamics and its relationship with neurodegenerative diseases and discuss current evidence and controversies surrounding the role of parkin in mitochondrial quality control and its relevance to PD pathogenesis. Although the emerging field of parkin-mediated mitochondrial quality control has proven to be exciting, it is important to recognize that PD pathogenesis is likely to involve an intricate network of interacting pathways. Elucidating the reciprocity of pathways, particularly how other PD-related pathways potentially influence mitochondrial homeostasis, may hold the key to therapeutic development.

Biogenesis of iron-sulfur clusters in mammalian cells: new insights and relevance to human disease

PubMed Central

Rouault, Tracey A.

2012-01-01

Iron-sulfur (Fe-S) clusters are ubiquitous cofactors composed of iron and inorganic sulfur. They are required for the function of proteins involved in a wide range of activities, including electron transport in respiratory chain complexes, regulatory sensing, photosynthesis and DNA repair. The proteins involved in the biogenesis of Fe-S clusters are evolutionarily conserved from bacteria to humans, and many insights into the process of Fe-S cluster biogenesis have come from studies of model organisms, including bacteria, fungi and plants. It is now clear that several rare and seemingly dissimilar human diseases are attributable to defects in the basic process of Fe-S cluster biogenesis. Although these diseases –which include Friedreich’s ataxia (FRDA), ISCU myopathy, a rare form of sideroblastic anemia, an encephalomyopathy caused by dysfunction of respiratory chain complex I and multiple mitochondrial dysfunctions syndrome – affect different tissues, a feature common to many of them is that mitochondrial iron overload develops as a secondary consequence of a defect in Fe-S cluster biogenesis. This Commentary outlines the basic steps of Fe-S cluster biogenesis as they have been defined in model organisms. In addition, it draws attention to refinements of the process that might be specific to the subcellular compartmentalization of Fe-S cluster biogenesis proteins in some eukaryotes, including mammals. Finally, it outlines several important unresolved questions in the field that, once addressed, should offer important clues into how mitochondrial iron homeostasis is regulated, and how dysfunction in Fe-S cluster biogenesis can contribute to disease. PMID:22382365

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis.

PubMed

Boulet, Aren; Vest, Katherine E; Maynard, Margaret K; Gammon, Micah G; Russell, Antoinette C; Mathews, Alexander T; Cole, Shelbie E; Zhu, Xinyu; Phillips, Casey B; Kwong, Jennifer Q; Dodani, Sheel C; Leary, Scot C; Cobine, Paul A

2018-02-09

Copper is required for the activity of cytochrome c oxidase (COX), the terminal electron-accepting complex of the mitochondrial respiratory chain. The likely source of copper used for COX biogenesis is a labile pool found in the mitochondrial matrix. In mammals, the proteins that transport copper across the inner mitochondrial membrane remain unknown. We previously reported that the mitochondrial carrier family protein Pic2 in budding yeast is a copper importer. The closest Pic2 ortholog in mammalian cells is the mitochondrial phosphate carrier SLC25A3. Here, to investigate whether SLC25A3 also transports copper, we manipulated its expression in several murine and human cell lines. SLC25A3 knockdown or deletion consistently resulted in an isolated COX deficiency in these cells, and copper addition to the culture medium suppressed these biochemical defects. Consistent with a conserved role for SLC25A3 in copper transport, its heterologous expression in yeast complemented copper-specific defects observed upon deletion of PIC2 Additionally, assays in Lactococcus lactis and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both in vitro and in vivo . © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

TLR-activated repression of Fe-S cluster biogenesis drives a metabolic shift and alters histone and tubulin acetylation.

PubMed

Tong, Wing-Hang; Maio, Nunziata; Zhang, De-Liang; Palmieri, Erika M; Ollivierre, Hayden; Ghosh, Manik C; McVicar, Daniel W; Rouault, Tracey A

2018-05-22

Given the essential roles of iron-sulfur (Fe-S) cofactors in mediating electron transfer in the mitochondrial respiratory chain and supporting heme biosynthesis, mitochondrial dysfunction is a common feature in a growing list of human Fe-S cluster biogenesis disorders, including Friedreich ataxia and GLRX5-related sideroblastic anemia. Here, our studies showed that restriction of Fe-S cluster biogenesis not only compromised mitochondrial oxidative metabolism but also resulted in decreased overall histone acetylation and increased H3K9me3 levels in the nucleus and increased acetylation of α-tubulin in the cytosol by decreasing the lipoylation of the pyruvate dehydrogenase complex, decreasing levels of succinate dehydrogenase and the histone acetyltransferase ELP3, and increasing levels of the tubulin acetyltransferase MEC17. Previous studies have shown that the metabolic shift in Toll-like receptor (TLR)-activated myeloid cells involves rapid activation of glycolysis and subsequent mitochondrial respiratory failure due to nitric oxide (NO)-mediated damage to Fe-S proteins. Our studies indicated that TLR activation also actively suppresses many components of the Fe-S cluster biogenesis machinery, which exacerbates NO-mediated damage to Fe-S proteins by interfering with cluster recovery. These results reveal new regulatory pathways and novel roles of the Fe-S cluster biogenesis machinery in modifying the epigenome and acetylome and provide new insights into the etiology of Fe-S cluster biogenesis disorders.

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

PubMed

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

2017-02-01

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

Chromogranin A deficiency in transgenic mice leads to aberrant chromaffin granule biogenesis.

PubMed

Kim, Taeyoon; Zhang, Chun-fa; Sun, Ziqing; Wu, Heling; Loh, Y Peng

2005-07-27

The biogenesis of dense-core secretory granules (DCGs), organelles responsible for the storage and secretion of neurotransmitters and neuropeptides in chromaffin cells, is poorly understood. Chromogranin A (CgA), which binds catecholamines for storage in the lumen of chromaffin granules, has been shown to be involved in DCG biogenesis in neuroendocrine PC12 cells. Here, we report that downregulation of CgA expression in vivo by expressing antisense RNA against CgA in transgenic mice led to a significant reduction in DCG formation in adrenal chromaffin cells. The number of DCGs formed in CgA antisense transgenic mice was directly correlated with the amount of CgA present in adrenal medulla. In addition, DCGs showed an increase in size, with enlargement in the volume around the dense core, a phenomenon that occurs to maintain constant "free" catecholamine concentration in the lumen of these granules. The extent of DCG swelling was inversely correlated with the number of DCGs formed, as well as the amount of CgA present in the adrenal glands of CgA antisense transgenic mice. These data indicate an essential role of CgA in regulating chromaffin DCG biogenesis and catecholamine storage in vivo.

TLR-activated repression of Fe-S cluster biogenesis drives a metabolic shift and alters histone and tubulin acetylation

PubMed Central

Maio, Nunziata; Palmieri, Erika M.; Ollivierre, Hayden; Ghosh, Manik C.

2018-01-01

Given the essential roles of iron-sulfur (Fe-S) cofactors in mediating electron transfer in the mitochondrial respiratory chain and supporting heme biosynthesis, mitochondrial dysfunction is a common feature in a growing list of human Fe-S cluster biogenesis disorders, including Friedreich ataxia and GLRX5-related sideroblastic anemia. Here, our studies showed that restriction of Fe-S cluster biogenesis not only compromised mitochondrial oxidative metabolism but also resulted in decreased overall histone acetylation and increased H3K9me3 levels in the nucleus and increased acetylation of α-tubulin in the cytosol by decreasing the lipoylation of the pyruvate dehydrogenase complex, decreasing levels of succinate dehydrogenase and the histone acetyltransferase ELP3, and increasing levels of the tubulin acetyltransferase MEC17. Previous studies have shown that the metabolic shift in Toll-like receptor (TLR)–activated myeloid cells involves rapid activation of glycolysis and subsequent mitochondrial respiratory failure due to nitric oxide (NO)–mediated damage to Fe-S proteins. Our studies indicated that TLR activation also actively suppresses many components of the Fe-S cluster biogenesis machinery, which exacerbates NO-mediated damage to Fe-S proteins by interfering with cluster recovery. These results reveal new regulatory pathways and novel roles of the Fe-S cluster biogenesis machinery in modifying the epigenome and acetylome and provide new insights into the etiology of Fe-S cluster biogenesis disorders. PMID:29784770

Mitochondrial quality control: Easy come, easy go

PubMed Central

Stotland, Aleksandr; Gottlieb, Roberta A.

2015-01-01

“Friends come and go but enemies accumulate.”Arthur Bloch Mitochondrial networks in eukaryotic cells are maintained via regular cycles of degradation and biogenesis. These complex processes function in concert with one another to eliminate dysfunctional mitochondria in a specific and targeted manner and coordinate the biogenesis of new organelles. This review covers the two aspects of mitochondrial turnover, focusing on the main pathways and mechanisms involved. The review also summarizes the current methods and techniques for analyzing mitochondrial turnover in vivo and in vitro, from the whole animal proteome level to the level of single organelle. PMID:25596427

Mitochondrial metabolic reprogramming induced by calorie restriction.

PubMed

Martin-Montalvo, Alejandro; de Cabo, Rafael

2013-07-20

Calorie restriction (CR) is a known intervention that delays most aging processes. Most of the beneficial effects of CR are mediated by improved maintenance of mitochondrial performance in aged individuals. The control of mitochondrial biogenesis, apoptosis, and protein turnover is required for healthy aging. CR is able to induce molecular mechanisms that preserve oxidative capacity and decrease oxidative damage. Published data indicate that peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) is activated in old animals under CR conditions compared to ad libitum counterparts, enhancing mitochondrial biogenesis. Molecular regulation of PGC-1α has recently attracted significant research interest. We discuss the master regulators of energy metabolism such as AMP-activated protein kinase and sirtuin 1 among others that have been demonstrated to activate mitochondrial biogenesis through increased PGC-1α activity at transcriptional and post-translational levels. Additionally, we describe the latest findings that explain how CR promotes mitochondrial efficiency and decreases mitochondrial-derived oxidative damage. Understanding the beneficial mitochondrial changes conferred by CR will aid design of therapies for age-related diseases and help slow the aging process. Given the difficulty for humans to adhere to CR, we also explore new molecules that have been proposed during the last years to mimic the CR phenotype and their potential as future therapeutics.

Elevated PGC-1α activity sustains mitochondrial biogenesis and muscle function without extending survival in a mouse model of inherited ALS.

PubMed

Da Cruz, Sandrine; Parone, Philippe A; Lopes, Vanda S; Lillo, Concepción; McAlonis-Downes, Melissa; Lee, Sandra K; Vetto, Anne P; Petrosyan, Susanna; Marsala, Martin; Murphy, Anne N; Williams, David S; Spiegelman, Bruce M; Cleveland, Don W

2012-05-02

The transcriptional coactivator PGC-1α induces multiple effects on muscle, including increased mitochondrial mass and activity. Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, adult-onset neurodegenerative disorder characterized by selective loss of motor neurons and skeletal muscle degeneration. An early event is thought to be denervation-induced muscle atrophy accompanied by alterations in mitochondrial activity and morphology within muscle. We now report that elevation of PGC-1α levels in muscles of mice that develop fatal paralysis from an ALS-causing SOD1 mutant elevates PGC-1α-dependent pathways throughout disease course. Mitochondrial biogenesis and activity are maintained through end-stage disease, accompanied by retention of muscle function, delayed muscle atrophy, and significantly improved muscle endurance even at late disease stages. However, survival was not extended. Therefore, muscle is not a primary target of mutant SOD1-mediated toxicity, but drugs increasing PGC-1α activity in muscle represent an attractive therapy for maintaining muscle function during progression of ALS. Copyright © 2012 Elsevier Inc. All rights reserved.

Targeting mitochondrial respiration as a therapeutic strategy for cervical cancer.

PubMed

Tian, Shenglan; Chen, Heng; Tan, Wei

2018-05-23

Targeting mitochondrial respiration has been documented as an effective therapeutic strategy in cancer. However, the impact of mitochondrial respiration inhibition on cervical cancer cells are not well elucidated. Using a panel of cervical cancer cell lines, we show that an existing drug atovaquone is active against the cervical cancer cells with high profiling of mitochondrial biogenesis. Atovaquone inhibited proliferation and induced apoptosis with varying efficacy among cervical cancer cell lines regardless of HPV infection, cellular origin and their sensitivity to paclitaxel. We further demonstrated that atovaquone acts on cervical cancer cells via inhibiting mitochondrial respiration. In particular, atovaquone specifically inhibited mitochondrial complex III but not I, II or IV activity, leading to respiration inhibition and energy crisis. Importantly, we found that the different sensitivity of cervical cancer cell lines to atovaquone were due to their differential level of mitochondrial biogenesis and dependency to mitochondrial respiration. In addition, we demonstrated that the in vitro observations were translatable to in vivo cervical cancer xenograft mouse model. Our findings suggest that the mitochondrial biogenesis varies among patients with cervical cancer. Our work also suggests that atovaquone is a useful addition to cervical cancer treatment, particularly to those with high dependency on mitochondrial respiration. Copyright © 2018 Elsevier Inc. All rights reserved.

Arabidopsis DAYU/ABERRANT PEROXISOME MORPHOLOGY9 Is a Key Regulator of Peroxisome Biogenesis and Plays Critical Roles during Pollen Maturation and Germination in Planta[W

PubMed Central

Li, Xin-Ran; Li, Hong-Ju; Yuan, Li; Liu, Man; Shi, Dong-Qiao; Liu, Jie; Yang, Wei-Cai

2014-01-01

Pollen undergo a maturation process to sustain pollen viability and prepare them for germination. Molecular mechanisms controlling these processes remain largely unknown. Here, we report an Arabidopsis thaliana mutant, dayu (dau), which impairs pollen maturation and in vivo germination. Molecular analysis indicated that DAU encodes the peroxisomal membrane protein ABERRANT PEROXISOME MORPHOLOGY9 (APEM9). DAU is transiently expressed from bicellular pollen to mature pollen during male gametogenesis. DAU interacts with peroxisomal membrane proteins PEROXIN13 (PEX13) and PEX16 in planta. Consistently, both peroxisome biogenesis and peroxisome protein import are impaired in dau pollen. In addition, the jasmonic acid (JA) level is significantly decreased in dau pollen, and the dau mutant phenotype is partially rescued by exogenous application of JA, indicating that the male sterility is mainly due to JA deficiency. In addition, the phenotypic survey of peroxin mutants indicates that the PEXs most likely play different roles in pollen germination. Taken together, these data indicate that DAU/APEM9 plays critical roles in peroxisome biogenesis and function, which is essential for JA production and pollen maturation and germination. PMID:24510720

Leucine modulation of mitochondrial mass and oxygen consumption in skeletal muscle cells and adipocytes

PubMed Central

Sun, Xiaocun; Zemel, Michael B

2009-01-01

Background The effects of dairy on energy metabolism appear to be mediated, in part, by leucine and calcium which regulate both adipocyte and skeletal muscle energy metabolism. We recently demonstrated that leucine and calcitriol regulate fatty acid oxidation in skeletal muscle cells in vitro, with leucine promoting and calcitriol suppressing fatty acid oxidation. Moreover, leucine coordinately regulated adipocyte lipid metabolism to promote flux of lipid to skeletal muscle and regulate metabolic flexibility. We have now investigated the role of mitochondrial biogenesis in mediating these effects. Methods We tested the effect of leucine, calcitriol and calcium in regulation of mitochondrial mass using a fluorescence method and tested mitochondrial biogenesis regulatory genes as well mitochondrial component genes using real-time PCR. We also evaluated the effect of leucine on oxygen consumption with a modified perfusion system. Results Leucine (0.5 mM) increased mitochondrial mass by 30% and 53% in C2C12 myocytes and 3T3-L1 adipocytes, respectively, while calcitriol (10 nM) decreased mitochondrial abundance by 37% and 27% (p < 0.02). Leucine also stimulated mitochondrial biogenesis genes SIRT-1, PGC-1α and NRF-1 as well as mitochondrial component genes UCP3, COX, and NADH expression by 3–5 fold in C2C12 cells (p < 0.003). Adipocyte-conditioned medium reduced mitochondrial abundance (p < 0.001) and decreased UCP3 but increased PGC-1α expression in myocytes, suggesting a feedback stimulation of mitochondrial biogenesis. Similar data were observed in C2C12 myocytes co-cultured with adipocytes, with co-culture markedly suppressing mitochondrial abundance (p < 0.02). Leucine stimulated oxygen consumption in both C2C12 cells and adipocytes compared with either control or valine-treated cells. Transfection of C2C12 myocytes with SIRT-1 siRNA resulted in parallel suppression of SIRT-1 expression and leucine-induced stimulation of PGC-1α and NRF-1, indicating that SIRT

Mitochondrial Metabolic Reprogramming Induced by Calorie Restriction

PubMed Central

Martin-Montalvo, Alejandro

2013-01-01

Abstract Significance: Calorie restriction (CR) is a known intervention that delays most aging processes. Most of the beneficial effects of CR are mediated by improved maintenance of mitochondrial performance in aged individuals. The control of mitochondrial biogenesis, apoptosis, and protein turnover is required for healthy aging. CR is able to induce molecular mechanisms that preserve oxidative capacity and decrease oxidative damage. Recent Advances and Critical Issues: Published data indicate that peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) is activated in old animals under CR conditions compared to ad libitum counterparts, enhancing mitochondrial biogenesis. Molecular regulation of PGC-1α has recently attracted significant research interest. We discuss the master regulators of energy metabolism such as AMP-activated protein kinase and sirtuin 1 among others that have been demonstrated to activate mitochondrial biogenesis through increased PGC-1α activity at transcriptional and post-translational levels. Additionally, we describe the latest findings that explain how CR promotes mitochondrial efficiency and decreases mitochondrial-derived oxidative damage. Future Directions: Understanding the beneficial mitochondrial changes conferred by CR will aid design of therapies for age-related diseases and help slow the aging process. Given the difficulty for humans to adhere to CR, we also explore new molecules that have been proposed during the last years to mimic the CR phenotype and their potential as future therapeutics. Antioxid. Redox Signal. 19, 310–320. PMID:22901095

Thyrotropin-releasing hormone controls mitochondrial biology in human epidermis.

PubMed

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

2012-03-01

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

Human Mitochondrial Protein Database

National Institute of Standards and Technology Data Gateway

SRD 131 Human Mitochondrial Protein Database (Web, free access)   The Human Mitochondrial Protein Database (HMPDb) provides comprehensive data on mitochondrial and human nuclear encoded proteins involved in mitochondrial biogenesis and function. This database consolidates information from SwissProt, LocusLink, Protein Data Bank (PDB), GenBank, Genome Database (GDB), Online Mendelian Inheritance in Man (OMIM), Human Mitochondrial Genome Database (mtDB), MITOMAP, Neuromuscular Disease Center and Human 2-D PAGE Databases. This database is intended as a tool not only to aid in studying the mitochondrion but in studying the associated diseases.

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

Silymarin protects against renal injury through normalization of lipid metabolism and mitochondrial biogenesis in high fat-fed mice.

PubMed

Bin Feng; Meng, Ran; Bin Huang; Bi, Yan; Shen, Shanmei; Zhu, Dalong

2017-09-01

Obesity is associated with an increased risk of chronic kidney diseases and the conventional treatment with renin-angiotensin-aldosterone system (RAAS) inhibitors is not enough to prevent renal injury and prolong the progression of disease. Recently, silymarin has shown protective effects on renal tissue injury, but the underlying mechanisms remain elusive. The goal of this study was to investigate the potential capacity of silymarin to prevent renal injury during obesity induced by high fat diet (HFD) in mice. In vivo, male C57BL/6 mice received HFD (60% of total calories) for 12 weeks, randomized and treated orally with vehicle saline or silymarin (30mg/kg body weight/d) for 4 weeks. In vitro, human proximal tubular epithelial cells (HK2) were exposed to 300μM palmitic acid (PA) for 36h followed by silymarin administration at different concentrations. The administration of silymarin significantly ameliorated HFD induced glucose metabolic disorders, oxidative stress and pathological alterations in the kidney. Silymarin significantly mitigated renal lipid accumulation, fatty acid β-oxidation and mitochondrial biogenesis in HFD mice and PA treated HK2 cells. Furthermore, silymarin partly restored mitochondrial membrane potential of HK2 cells after PA exposure. In conclusion, silymarin can improve oxidative stress and preserve mitochondrial dysfunction in the kidney, potentially via preventing accumulation of renal lipids and fatty acid β-oxidation. Copyright © 2017. Published by Elsevier Inc.

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-12-01

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

Morinda citrifolia leaf enhanced performance by improving angiogenesis, mitochondrial biogenesis, antioxidant, anti-inflammatory & stress responses.

PubMed

Mohamad Shalan, Nor Aijratul Asikin; Mustapha, Noordin M; Mohamed, Suhaila

2016-12-01

Morinda citrifolia fruit, (noni), enhanced performances in athletes and post-menopausal women in clinical studies. This report shows the edible noni leaves water extract enhances performance in a weight-loaded swimming animal model better than the fruit or standardized green tea extract. The 4weeks study showed the extract (containing scopoletin and epicatechin) progressively prolonged the time to exhaustion by threefold longer than the control, fruit or tea extract. The extract improved (i) the mammalian antioxidant responses (MDA, GSH and SOD2 levels), (ii) tissue nutrient (glucose) and metabolite (lactate) management, (iii) stress hormone (cortisol) regulation; (iv) neurotransmitter (dopamine, noradrenaline, serotonin) expressions, transporter or receptor levels, (v) anti-inflammatory (IL4 & IL10) responses; (v) skeletal muscle angiogenesis (VEGFA) and (v) energy and mitochondrial biogenesis (via PGC, UCP3, NRF2, AMPK, MAPK1, and CAMK4). The ergogenic extract helped delay fatigue by enhancing energy production, regulation and efficiency, which suggests benefits for physical activities and disease recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Alternative function for the mitochondrial SAM complex in biogenesis of alpha-helical TOM proteins.

PubMed

Stojanovski, Diana; Guiard, Bernard; Kozjak-Pavlovic, Vera; Pfanner, Nikolaus; Meisinger, Chris

2007-12-03

The mitochondrial outer membrane contains two preprotein translocases: the general translocase of outer membrane (TOM) and the beta-barrel-specific sorting and assembly machinery (SAM). TOM functions as the central entry gate for nuclear-encoded proteins. The channel-forming Tom40 is a beta-barrel protein, whereas all Tom receptors and small Tom proteins are membrane anchored by a transmembrane alpha-helical segment in their N- or C-terminal portion. Synthesis of Tom precursors takes place in the cytosol, and their import occurs via preexisting TOM complexes. The precursor of Tom40 is then transferred to SAM for membrane insertion and assembly. Unexpectedly, we find that the biogenesis of alpha-helical Tom proteins with a membrane anchor in the C-terminal portion is SAM dependent. Each SAM protein is necessary for efficient membrane integration of the receptor Tom22, whereas assembly of the small Tom proteins depends on Sam37. Thus, the substrate specificity of SAM is not restricted to beta-barrel proteins but also includes the majority of alpha-helical Tom proteins.

Ononitol monohydrate enhances PRDM16 & UCP-1 expression, mitochondrial biogenesis and insulin sensitivity via STAT6 and LTB4R in maturing adipocytes.

PubMed

Subash-Babu, P; Alshatwi, Ali A

2018-03-01

Ononitol monohydrate (OMH), a glycoside was originally isolated from Cassia tora (Linn.). Glycosides regulate lipid metabolism but scientific validation desired. Hence, we aimed to evaluate the effect of OMH on enhancing mitochondrial potential, mitochondrial biogenesis, upregulate the expression of brown adipogenesis specific genes in maturing adipocytes. In addition, we observed the inter-relation between adipocyte and T-lymphocyte; whether, OMH treated adipocyte-condition medium stimulate T-cell chemokine linked with insulin resistance. In a dose dependent manner OMH treated to preadipocyte significantly inhibited maturation and enhanced mitochondrial biogenesis, it was confirmed by Oil red 'O and Nile red stain without inducing cytotoxicity. The mRNA levels of adipocyte browning related genes such as, PR domain containing 16 (PRDM16), peroxisome proliferator activated receptor gamma coactivator 1 alpha (PPARγC1α) and uncoupling protein-1 (UCP-1) have been significantly upregulated. In addition, adipogenic transcription factors [such as proliferator activated receptor γ (PPARγ), CCAAT/enhancer binding protein (C/EBPα) and sterol regulatory element binding protein-1c (SREBP-1c)] and adipogenic genes were significantly down-regulated by treatment with OMH when compared to control cells. Protein expression levels of adiponectin have been increased; leptin, C/EBPα and leukotriene B4 receptor (LTB4R) were down regulated by OMH in mature adipocytes. In addition, adipocyte condition medium and OMH treated T-lymphocyte, significantly increased insulin signaling pathway related mRNAs, such as interlukin-4 (IL-4), signal transducer and activator of transcription 6 (STAT 6 ) and decreased leukotriene B4 (LTB 4 ). The present findings suggest that OMH increased browning factors in differentiating and maturing preadipocyte also decreased adipose tissue inflammation as well as the enhanced insulin signaling. Copyright © 2018. Published by Elsevier Masson SAS.

Loss of the mitochondrial protein-only ribonuclease P complex causes aberrant tRNA processing and lethality in Drosophila.

PubMed

Sen, Aditya; Karasik, Agnes; Shanmuganathan, Aranganathan; Mirkovic, Elena; Koutmos, Markos; Cox, Rachel T

2016-07-27

Proteins encoded by mitochondrial DNA are translated using mitochondrially encoded tRNAs and rRNAs. As with nuclear encoded tRNAs, mitochondrial tRNAs must be processed to become fully functional. The mitochondrial form of ribonuclease P (mt:RNase P) is responsible for 5'-end maturation and is comprised of three proteins; mitochondrial RNase P protein (MRPP) 1 and 2 together with proteinaceous RNase P (PRORP). However, its mechanism and impact on development is not yet known. Using homology searches, we have identified the three proteins composing Drosophila mt:RNase P: Mulder (PRORP), Scully (MRPP2) and Roswell (MRPP1). Here, we show that each protein is essential and localizes with mitochondria. Furthermore, reducing levels of each causes mitochondrial deficits, which appear to be due at least in part to defective mitochondrial tRNA processing. Overexpressing two members of the complex, Mulder and Roswell, is also lethal, and in the case of Mulder, causes abnormal mitochondrial morphology. These data are the first evidence that defective mt:RNase P causes mitochondrial dysfunction, lethality and aberrant mitochondrial tRNA processing in vivo, underscoring its physiological importance. This in vivo mt:RNase P model will advance our understanding of how loss of mitochondrial tRNA processing causes tissue failure, an important aspect of human mitochondrial disease. Published by Oxford University Press on behalf of Nucleic Acids Research 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Molecular Genetics of Mitochondrial Disorders

ERIC Educational Resources Information Center

Wong, Lee-Jun C.

2010-01-01

Mitochondrial respiratory chain (RC) disorders (RCDs) are a group of genetically and clinically heterogeneous diseases because of the fact that protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis, structure, and function of mitochondria, including DNA…

NAD+-Dependent Activation of Sirt1 Corrects the Phenotype in a Mouse Model of Mitochondrial Disease

PubMed Central

Cerutti, Raffaele; Pirinen, Eija; Lamperti, Costanza; Marchet, Silvia; Sauve, Anthony A.; Li, Wei; Leoni, Valerio; Schon, Eric A.; Dantzer, Françoise; Auwerx, Johan; Viscomi, Carlo; Zeviani, Massimo

2014-01-01

Summary Mitochondrial disorders are highly heterogeneous conditions characterized by defects of the mitochondrial respiratory chain. Pharmacological activation of mitochondrial biogenesis has been proposed as an effective means to correct the biochemical defects and ameliorate the clinical phenotype in these severely disabling, often fatal, disorders. Pathways related to mitochondrial biogenesis are targets of Sirtuin1, a NAD+-dependent protein deacetylase. As NAD+ boosts the activity of Sirtuin1 and other sirtuins, intracellular levels of NAD+ play a key role in the homeostatic control of mitochondrial function by the metabolic status of the cell. We show here that supplementation with nicotinamide riboside, a natural NAD+ precursor, or reduction of NAD+ consumption by inhibiting the poly(ADP-ribose) polymerases, leads to marked improvement of the respiratory chain defect and exercise intolerance of the Sco2 knockout/knockin mouse, a mitochondrial disease model characterized by impaired cytochrome c oxidase biogenesis. This strategy is potentially translatable into therapy of mitochondrial disorders in humans. PMID:24814483

β-Catenin Knockdown Affects Mitochondrial Biogenesis and Lipid Metabolism in Breast Cancer Cells.

PubMed

Vergara, Daniele; Stanca, Eleonora; Guerra, Flora; Priore, Paola; Gaballo, Antonio; Franck, Julien; Simeone, Pasquale; Trerotola, Marco; De Domenico, Stefania; Fournier, Isabelle; Bucci, Cecilia; Salzet, Michel; Giudetti, Anna M; Maffia, Michele

2017-01-01

β-catenin plays an important role as regulatory hub in several cellular processes including cell adhesion, metabolism, and epithelial mesenchymal transition. This is mainly achieved by its dual role as structural component of cadherin-based adherens junctions, and as a key nuclear effector of the Wnt pathway. For this dual role, different classes of proteins are differentially regulated via β-catenin dependent mechanisms. Here, we applied a liquid chromatography-mass spectrometry (LC-MS/MS) approach to identify proteins modulated after β-catenin knockdown in the breast cancer cell line MCF-7. We used a label free analysis to compare trypsin-digested proteins from CTR (shCTR) and β-catenin knockout cells (shβcat). This led to the identification of 98 differentially expressed proteins, 53 of them were up-regulated and 45 down-regulated. Loss of β-catenin induced morphological changes and a significant modulation of the expression levels of proteins associated with primary metabolic processes. In detail, proteins involved in carbohydrate metabolism and tricarboxylic acid cycle were found to be down-regulated, whereas proteins associated to lipid metabolism were found up-regulated in shβcat compared to shCTR. A loss of mitochondrial mass and membrane potential was also assessed by fluorescent probes in shβcat cells with respect to the controls. These data are consistent with the reduced expression of transcriptional factors regulating mitochondrial biogenesis detected in shβcat cells. β-catenin driven metabolic reprogramming resulted also in a significant modulation of lipogenic enzyme expression and activity. Compared to controls, β-catenin knockout cells showed increased incorporation of [1- 14 C]acetate and decreased utilization of [U- 14 C]glucose for fatty acid synthesis. Our data highlight a role of β-catenin in the regulation of metabolism and energy homeostasis in breast cancer cells.

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

Mammalian Fe-S cluster biogenesis and its implication in disease.

PubMed

Beilschmidt, Lena K; Puccio, Hélène M

2014-05-01

Iron-sulfur (Fe-S) clusters are inorganic cofactors that are ubiquitous and essential. Due to their chemical versatility, Fe-S clusters are implicated in a wide range of protein functions including mitochondrial respiration and DNA repair. Composed of iron and sulfur, they are sensible to oxygen and their biogenesis requires a highly conserved protein machinery that facilitates assembly of the cluster as well as its insertion into apoproteins. Mitochondria are the central cellular compartment for Fe-S cluster biogenesis in eukaryotic cells and the importance of proper function of this biogenesis for life is highlighted by a constantly increasing number of human genetic diseases that are associated with dysfunction of this Fe-S cluster biogenesis pathway. Although these disorders are rare and appear dissimilar, common aspects are found among them. This review will give an overview on what is known on mammalian Fe-S cluster biogenesis today, by putting it into the context of what is known from studies from lower model organisms, and focuses on the associated diseases, by drawing attention to the respective mutations. Finally, it outlines the importance of adequate cellular and murine models to uncover not only each protein function, but to resolve their role and requirement throughout the mammalian organism. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Effective treatment of mitochondrial myopathy by nicotinamide riboside, a vitamin B3

PubMed Central

Khan, Nahid A; Auranen, Mari; Paetau, Ilse; Pirinen, Eija; Euro, Liliya; Forsström, Saara; Pasila, Lotta; Velagapudi, Vidya; Carroll, Christopher J; Auwerx, Johan; Suomalainen, Anu

2014-01-01

Nutrient availability is the major regulator of life and reproduction, and a complex cellular signaling network has evolved to adapt organisms to fasting. These sensor pathways monitor cellular energy metabolism, especially mitochondrial ATP production and NAD+/NADH ratio, as major signals for nutritional state. We hypothesized that these signals would be modified by mitochondrial respiratory chain disease, because of inefficient NADH utilization and ATP production. Oral administration of nicotinamide riboside (NR), a vitamin B3 and NAD+ precursor, was previously shown to boost NAD+ levels in mice and to induce mitochondrial biogenesis. Here, we treated mitochondrial myopathy mice with NR. This vitamin effectively delayed early- and late-stage disease progression, by robustly inducing mitochondrial biogenesis in skeletal muscle and brown adipose tissue, preventing mitochondrial ultrastructure abnormalities and mtDNA deletion formation. NR further stimulated mitochondrial unfolded protein response, suggesting its protective role in mitochondrial disease. These results indicate that NR and strategies boosting NAD+ levels are a promising treatment strategy for mitochondrial myopathy. PMID:24711540

NAD(+)-dependent activation of Sirt1 corrects the phenotype in a mouse model of mitochondrial disease.

PubMed

Cerutti, Raffaele; Pirinen, Eija; Lamperti, Costanza; Marchet, Silvia; Sauve, Anthony A; Li, Wei; Leoni, Valerio; Schon, Eric A; Dantzer, Françoise; Auwerx, Johan; Viscomi, Carlo; Zeviani, Massimo

2014-06-03

Mitochondrial disorders are highly heterogeneous conditions characterized by defects of the mitochondrial respiratory chain. Pharmacological activation of mitochondrial biogenesis has been proposed as an effective means to correct the biochemical defects and ameliorate the clinical phenotype in these severely disabling, often fatal, disorders. Pathways related to mitochondrial biogenesis are targets of Sirtuin1, a NAD(+)-dependent protein deacetylase. As NAD(+) boosts the activity of Sirtuin1 and other sirtuins, intracellular levels of NAD(+) play a key role in the homeostatic control of mitochondrial function by the metabolic status of the cell. We show here that supplementation with nicotinamide riboside, a natural NAD(+) precursor, or reduction of NAD(+) consumption by inhibiting the poly(ADP-ribose) polymerases, leads to marked improvement of the respiratory chain defect and exercise intolerance of the Sco2 knockout/knockin mouse, a mitochondrial disease model characterized by impaired cytochrome c oxidase biogenesis. This strategy is potentially translatable into therapy of mitochondrial disorders in humans. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Green Tea Polyphenols Stimulate Mitochondrial Biogenesis and Improve Renal Function after Chronic Cyclosporin A Treatment in Rats

PubMed Central

Rehman, Hasibur; Krishnasamy, Yasodha; Haque, Khujista; Lemasters, John J.; Schnellmann, Rick G.; Zhong, Zhi

2013-01-01

Our previous studies showed that an extract from Camellia sinenesis (green tea), which contains several polyphenols, attenuates nephrotoxicity caused by cyclosporine A (CsA). Since polyphenols are stimulators of mitochondrial biogenesis (MB), this study investigated whether stimulation of MB plays a role in green tea polyphenol protection against CsA renal toxicity. Rats were fed a powdered diet containing green tea polyphenolic extract (0.1%) starting 3 days prior to CsA treatment (25 mg/kg, i.g. daily for 3 weeks). CsA alone decreased renal nuclear DNA-encoded oxidative phosphorylation (OXPHOS) protein ATP synthase-β (AS-β) by 42%, mitochondrial DNA (mtDNA)-encoded OXPHOS protein NADH dehydrogenase-3 (ND3) by 87% and their associated mRNAs. Mitochondrial DNA copy number was also decreased by 78% by CsA. Immunohistochemical analysis showed decreased cytochrome c oxidase subunit IV (COX-IV), an OXPHOS protein, in tubular cells. Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, the master regulator of MB, and mitochondrial transcription factor-A (Tfam), the transcription factor that regulates mtDNA replication and transcription, were 42% and 90% lower, respectively, in the kidneys of CsA-treated than in untreated rats. These results indicate suppression of MB by chronic CsA treatment. Green tea polyphenols alone and following CsA increased AS-β, ND3, COX-IV, mtDNA copy number, PGC-1α mRNA and protein, decreased acetylated PGC-1α, and increased Tfam mRNA and protein. In association with suppressed MB, CsA increased serum creatinine, caused loss of brush border and dilatation of proximal tubules, tubular atrophy, vacuolization, apoptosis, calcification, and increased neutrophil gelatinase-associated lipocalin expression, leukocyte infiltration, and renal fibrosis. Green tea polyphenols markedly attenuated CsA-induced renal injury and improved renal function. Together, these results demonstrate that green tea polyphenols attenuate Cs

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

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

PubMed

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

2017-01-01

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

Methods to study the biogenesis of membrane proteins in yeast mitochondria.

PubMed

Weckbecker, Daniel; Herrmann, Johannes M

2013-01-01

The biogenesis of mitochondrial membrane proteins is an intricate process that relies on the import and submitochondrial sorting of nuclear-encoded preproteins and on the synthesis of mitochondrial translation products in the matrix. Subsequently, these polypeptides need to be inserted into the outer and the inner membranes of the organelle where many of them assemble into multisubunit complexes. In this chapter we provide established protocols to study these different processes experimentally using mitochondria of budding yeast. In particular, methods are described in detail to purify mitochondria, to study mitochondrial protein synthesis, to follow the import of radiolabeled preproteins into isolated mitochondria, and to assess membrane association and the aggregation of mitochondrial proteins by fractionation. These protocols and a list of dos and don'ts shall enable beginners and experienced scientists to address the targeting and assembly of mitochondrial membrane proteins.

Pharmacological approaches to restore mitochondrial function

PubMed Central

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

2014-01-01

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

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

Melanocortin 4 Receptor Activation Attenuates Mitochondrial Dysfunction in Skeletal Muscle of Diabetic Rats.

PubMed

Zhang, Hao-Hao; Liu, Jiao; Qin, Gui-Jun; Li, Xia-Lian; Du, Pei-Jie; Hao, Xiao; Zhao, Di; Tian, Tian; Wu, Jing; Yun, Meng; Bai, Yan-Hui

2017-11-01

A previous study has confirmed that the central melanocortin system was able to mediate skeletal muscle AMP-activated protein kinase (AMPK) activation in mice fed a high-fat diet, while activation of the AMPK signaling pathway significantly induced mitochondrial biogenesis. Our hypothesis was that melanocortin 4 receptor (MC4R) was involved in the development of skeletal muscle injury in diabetic rats. In this study, we treated diabetic rats intracerebroventricularly with MC4R agonist R027-3225 or antagonist SHU9119, respectively. Then, we measured the production of reactive oxygen species (ROS), the levels of malondialdehyde (MDA) and glutathione (GSH), the mitochondrial DNA (mtDNA) content and mitochondrial biogenesis, and the protein levels of p-AMPK, AMPK, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), sirtuin 1 (SIRT1), and manganese superoxide dismutase (MnSOD) in the skeletal muscle of diabetic rats. The results showed that there was significant skeletal muscle injury in the diabetic rats along with serious oxidative stress and decreased mitochondrial biogenesis. Treatment with R027-3225 reduced oxidative stress and induced mitochondrial biogenesis in skeletal muscle, and also activated the AMPK-SIRT1-PGC-1α signaling pathway. However, diabetic rats injected with MC4R antagonist SHU9119 showed an aggravated oxidative stress and mitochondrial dysfunction in skeletal muscle. In conclusion, our results revealed that MC4R activation was able to attenuate oxidative stress and mitochondrial dysfunction in skeletal muscle induced by diabetes partially through activating the AMPK-SIRT1-PGC-1α signaling pathway. J. Cell. Biochem. 118: 4072-4079, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Medium-chain TAG improve energy metabolism and mitochondrial biogenesis in the liver of intra-uterine growth-retarded and normal-birth-weight weanling piglets.

PubMed

Zhang, Hao; Li, Yue; Hou, Xiang; Zhang, Lili; Wang, Tian

2016-05-01

We previously reported that medium-chain TAG (MCT) could alleviate hepatic oxidative damage in weanling piglets with intra-uterine growth retardation (IUGR). There is a relationship between oxidative status and energy metabolism, a process involved in substrate availability and glucose flux. Therefore, the aim of this study was to investigate the effects of IUGR and MCT on hepatic energy metabolism and mitochondrial function in weanling piglets. Twenty-four IUGR piglets and twenty-four normal-birth-weight (NBW) piglets were fed a diet of either soyabean oil (SO) or MCT from 21 d of postnatal age to 49 d of postnatal age. Then, the piglets' biochemical parameters and gene expressions related to energy metabolism and mitochondrial function were determined (n 4). Compared with NBW, IUGR decreased the ATP contents and succinate oxidation rates in the liver of piglets, and reduced hepatic mitochondrial citrate synthase (CS) activity (P<0·05). IUGR piglets exhibited reductions in hepatic mitochondrial DNA (mtDNA) contents and gene expressions related to mitochondrial biogenesis compared with NBW piglets (P<0·05). The MCT diet increased plasma ghrelin concentration and hepatic CS and succinate dehydrogenase activities, but decreased hepatic pyruvate kinase activity compared with the SO diet (P<0·05). The MCT-fed piglets showed improved mtDNA contents and PPARγ coactivator-1α expression in the liver (P<0·05). The MCT diet alleviated decreased mRNA abundance of the hepatic PPARα induced by IUGR (P<0·05). It can therefore be postulated that MCT may have beneficial effects in improving energy metabolism and mitochondrial function in weanling piglets.

Parkin loss leads to PARIS-dependent declines in mitochondrial mass and respiration

PubMed Central

Stevens, Daniel A.; Lee, Yunjong; Kang, Ho Chul; Lee, Byoung Dae; Lee, Yun-Il; Bower, Aaron; Jiang, Haisong; Kang, Sung-Ung; Andrabi, Shaida A.; Dawson, Valina L.; Shin, Joo-Ho; Dawson, Ted M.

2015-01-01

Mutations in parkin lead to early-onset autosomal recessive Parkinson’s disease (PD) and inactivation of parkin is thought to contribute to sporadic PD. Adult knockout of parkin in the ventral midbrain of mice leads to an age-dependent loss of dopamine neurons that is dependent on the accumulation of parkin interacting substrate (PARIS), zinc finger protein 746 (ZNF746), and its transcriptional repression of PGC-1α. Here we show that adult knockout of parkin in mouse ventral midbrain leads to decreases in mitochondrial size, number, and protein markers consistent with a defect in mitochondrial biogenesis. This decrease in mitochondrial mass is prevented by short hairpin RNA knockdown of PARIS. PARIS overexpression in mouse ventral midbrain leads to decreases in mitochondrial number and protein markers and PGC-1α–dependent deficits in mitochondrial respiration. Taken together, these results suggest that parkin loss impairs mitochondrial biogenesis, leading to declining function of the mitochondrial pool and cell death. PMID:26324925

Effective treatment of mitochondrial myopathy by nicotinamide riboside, a vitamin B3.

PubMed

Khan, Nahid A; Auranen, Mari; Paetau, Ilse; Pirinen, Eija; Euro, Liliya; Forsström, Saara; Pasila, Lotta; Velagapudi, Vidya; Carroll, Christopher J; Auwerx, Johan; Suomalainen, Anu

2014-06-01

Nutrient availability is the major regulator of life and reproduction, and a complex cellular signaling network has evolved to adapt organisms to fasting. These sensor pathways monitor cellular energy metabolism, especially mitochondrial ATP production and NAD(+)/NADH ratio, as major signals for nutritional state. We hypothesized that these signals would be modified by mitochondrial respiratory chain disease, because of inefficient NADH utilization and ATP production. Oral administration of nicotinamide riboside (NR), a vitamin B3 and NAD(+) precursor, was previously shown to boost NAD(+) levels in mice and to induce mitochondrial biogenesis. Here, we treated mitochondrial myopathy mice with NR. This vitamin effectively delayed early- and late-stage disease progression, by robustly inducing mitochondrial biogenesis in skeletal muscle and brown adipose tissue, preventing mitochondrial ultrastructure abnormalities and mtDNA deletion formation. NR further stimulated mitochondrial unfolded protein response, suggesting its protective role in mitochondrial disease. These results indicate that NR and strategies boosting NAD(+) levels are a promising treatment strategy for mitochondrial myopathy. © 2014 The Authors. Published under the terms of the CC BY license.

Biogenesis of cytosolic ribosomes requires the essential iron–sulphur protein Rli1p and mitochondria

PubMed Central

Kispal, Gyula; Sipos, Katalin; Lange, Heike; Fekete, Zsuzsanna; Bedekovics, Tibor; Janáky, Tamás; Bassler, Jochen; Aguilar Netz, Daili J; Balk, Janneke; Rotte, Carmen; Lill, Roland

2005-01-01

Mitochondria perform a central function in the biogenesis of cellular iron–sulphur (Fe/S) proteins. It is unknown to date why this biosynthetic pathway is indispensable for life, the more so as no essential mitochondrial Fe/S proteins are known. Here, we show that the soluble ATP-binding cassette (ABC) protein Rli1p carries N-terminal Fe/S clusters that require the mitochondrial and cytosolic Fe/S protein biogenesis machineries for assembly. Mutations in critical cysteine residues of Rli1p abolish association with Fe/S clusters and lead to loss of cell viability. Hence, the essential character of Fe/S clusters in Rli1p explains the indispensable character of mitochondria in eukaryotes. We further report that Rli1p is associated with ribosomes and with Hcr1p, a protein involved in rRNA processing and translation initiation. Depletion of Rli1p causes a nuclear export defect of the small and large ribosomal subunits and subsequently a translational arrest. Thus, ribosome biogenesis and function are intimately linked to the crucial role of mitochondria in the maturation of the essential Fe/S protein Rli1p. PMID:15660134

Increased 8-hydroxy-2'-deoxyguanosine in plasma and decreased mRNA expression of human 8-oxoguanine DNA glycosylase 1, anti-oxidant enzymes, mitochondrial biogenesis-related proteins and glycolytic enzymes in leucocytes in patients with systemic lupus erythematosus.

PubMed

Lee, H-T; Lin, C-S; Lee, C-S; Tsai, C-Y; Wei, Y-H

2014-04-01

We measured plasma levels of the oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) and leucocyte mRNA expression levels of the genes encoding the 8-OHdG repair enzyme human 8-oxoguanine DNA glycosylase 1 (hOGG1), the anti-oxidant enzymes copper/zinc superoxide dismutase (Cu/ZnSOD), manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase-1 (GPx-1), GPx-4, glutathione reductase (GR) and glutathione synthetase (GS), the mitochondrial biogenesis-related proteins mtDNA-encoded ND 1 polypeptide (ND1), ND6, ATPase 6, mitochondrial transcription factor A (Tfam), nuclear respiratory factor 1(NRF-1), pyruvate dehydrogenase E1 component alpha subunit (PDHA1), pyruvate dehydrogenase kinase isoenzyme 1 (PDK-1) and hypoxia inducible factor-1α (HIF-1α) and the glycolytic enzymes hexokinase-II (HK-II), glucose 6-phosphate isomerase (GPI), phosphofructokinase (PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase A (LDHa). We analysed their relevance to oxidative damage in 85 systemic lupus erythematosus (SLE) patients, four complicated SLE patients undergoing rituximab treatment and 45 healthy individuals. SLE patients had higher plasma 8-OHdG levels (P < 0·01) but lower leucocyte expression of the genes encoding hOGG1(P < 0·01), anti-oxidant enzymes (P < 0·05), mitochondrial biogenesis-related proteins (P < 0·05) and glycolytic enzymes (P < 0·05) than healthy individuals. The increase in plasma 8-OHdG was correlated positively with the elevation of leucocyte expression of the genes encoding hOGG1 (P < 0·05), anti-oxidant enzymes (P < 0·05), several mitochondrial biogenesis-related proteins (P < 0·05) and glycolytic enzymes (P < 0·05) in lupus patients. The patients, whose leucocyte mtDNA harboured D310 heteroplasmy, exhibited a positive correlation between the mtDNA copy number and expression of ND1, ND6 and ATPase 6 (P < 0·05) and a negative correlation between mt

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

PubMed Central

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

2014-01-01

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

Acetyl-L-carnitine activates the peroxisome proliferator-activated receptor-γ coactivators PGC-1α/PGC-1β-dependent signaling cascade of mitochondrial biogenesis and decreases the oxidized peroxiredoxins content in old rat liver.

PubMed

Pesce, Vito; Nicassio, Luigi; Fracasso, Flavio; Musicco, Clara; Cantatore, Palmiro; Gadaleta, Maria Nicola

2012-04-01

The behavior of the peroxisome proliferator-activated receptor-γ coactivators PGC-1α/PGC-β-dependent mitochondrial biogenesis signaling pathway, as well as the level of some antioxidant enzymes and proteins involved in mitochondrial dynamics in the liver of old rats before and after 2 months of acetyl-L-carnitine (ALCAR) supplementation, was tested. The results reveal that ALCAR treatment is able to reverse the age-associated decline of PGC-1α, PGC-1β, nuclear respiratory factor 1 (NRF-1), mitochondrial transcription factor A (TFAM), nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 1 (ND1), and cytochrome c oxidase subunit IV (COX IV) protein levels, of mitochondrial DNA (mtDNA) content, and of citrate synthase activity. Moreover, it partially reverses the mitochondrial superoxide dismutase 2 (SOD2) decline and reduces the cellular content of oxidized peroxiredoxins. These data demonstrate that ALCAR treatment is able to promote in the old rat liver a new mitochondrial population that can contribute to the cellular oxidative stress reduction. Furthermore, a remarkable decline of Drp1 and of Mfn2 proteins is reported here for the first time, suggesting a reduced mitochondrial dynamics in aging liver with no effect of ALCAR treatment.

Biogenesis of the mitochondrial TOM complex: Mim1 promotes insertion and assembly of signal-anchored receptors.

PubMed

Becker, Thomas; Pfannschmidt, Sylvia; Guiard, Bernard; Stojanovski, Diana; Milenkovic, Dusanka; Kutik, Stephan; Pfanner, Nikolaus; Meisinger, Chris; Wiedemann, Nils

2008-01-04

The translocase of the outer membrane (TOM complex) is the central entry gate for nuclear-encoded mitochondrial precursor proteins. All Tom proteins are also encoded by nuclear genes and synthesized as precursors in the cytosol. The channel-forming beta-barrel protein Tom40 is targeted to mitochondria via Tom receptors and inserted into the outer membrane by the sorting and assembly machinery (SAM complex). A further outer membrane protein, Mim1, plays a less defined role in assembly of Tom40 into the TOM complex. The three receptors Tom20, Tom22, and Tom70 are anchored in the outer membrane by a single transmembrane alpha-helix, located at the N terminus in the case of Tom20 and Tom70 (signal-anchored) or in the C-terminal portion in the case of Tom22 (tail-anchored). Insertion of the precursor of Tom22 into the outer membrane requires pre-existing Tom receptors while the import pathway of the precursors of Tom20 and Tom70 is only poorly understood. We report that Mim1 is required for efficient membrane insertion and assembly of Tom20 and Tom70, but not Tom22. We show that Mim1 associates with SAM(core) components to a large SAM complex, explaining its role in late steps of the assembly pathway of Tom40. We conclude that Mim1 is not only required for biogenesis of the beta-barrel protein Tom40 but also for membrane insertion and assembly of signal-anchored Tom receptors. Thus, Mim1 plays an important role in the efficient assembly of the mitochondrial TOM complex.

Resveratrol improves high-fat diet induced insulin resistance by rebalancing subsarcolemmal mitochondrial oxidation and antioxidantion.

PubMed

Haohao, Zhang; Guijun, Qin; Juan, Zheng; Wen, Kong; Lulu, Chen

2015-03-01

Although resveratrol (RES) is thought to be a key regulator of insulin sensitivity in rodents, the exact mechanism underlying this effect remains unclear. Therefore, we sought to investigate how RES affects skeletal muscle oxidative and antioxidant levels of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial populations in high-fat diet (HFD)-induced insulin resistance (IR) rats. Systemic and skeletal muscle insulin sensitivity together with expressions of several genes related to mitochondrial biogenesis and skeletal muscle SIRT1, SIRT3 protein levels were studied in rats fed a normal diet, a HFD, and a HFD with intervention of RES for 8 weeks. Oxidative stress levels and antioxidant enzyme activities were assessed in SS and IMF mitochondria. HFD fed rats exhibited obvious systemic and skeletal muscle IR as well as decreased SIRT1 and SIRT3 expressions, mitochondrial DNA (mtDNA), and mitochondrial biogenesis (p < 0.05). Both SS and IMF mitochondria demonstrated elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels. In addition, SS mitochondrial antioxidant enzyme activities were significantly lower, while IMF mitochondrial antioxidant enzyme activities were higher (p < 0.05). By contrast, RES treatment protected rats against diet induced IR, increased SIRT1 and SIRT3 expressions, mtDNA, and mitochondrial biogenesis (p < 0.05). Moreover, the activities of SS and IMF mitochondrial antioxidant enzymes were increased, which reverted the increased SS mitochondrial oxidative stress levels (p < 0.05). This study suggests that RES ameliorates insulin sensitivity consistent with improved SIRT3 expressions and rebalance between SS mitochondrial oxidative stress and antioxidant competence in HFD rats.

Autophagosome biogenesis in primary neurons follows an ordered and spatially regulated pathway.

PubMed

Maday, Sandra; Holzbaur, Erika L F

2014-07-14

Autophagy is an essential degradative pathway in neurons, yet little is known about mechanisms driving autophagy in highly polarized cells. Here, we use dual-color live-cell imaging to investigate the neuron-specific mechanisms of constitutive autophagosome biogenesis in primary dorsal root ganglion (DRG) and hippocampal cultures. Under basal conditions, autophagosomes are continuously generated in the axon tip. There is an ordered assembly of proteins recruited with stereotypical kinetics onto the developing autophagosome. Plasma- or mitochondrial-derived membranes were not incorporated into nascent autophagosomes in the distal axon. Rather, autophagosomes are generated at double FYVE-containing protein 1 (DFCP1)-positive subdomains of the endoplasmic reticulum (ER), distinct from ER exit sites. Biogenesis events are enriched distally; autophagosomes form infrequently in dendrites, the soma, or midaxon, consistent with a compartmentalized pathway for constitutive autophagy in primary neurons. Distal biogenesis may facilitate degradation of damaged mitochondria and long-lived cytoplasmic proteins reaching the axon tip via slow axonal transport. Copyright © 2014 Elsevier Inc. All rights reserved.

Contribution of Mössbauer spectroscopy to the investigation of Fe/S biogenesis.

PubMed

Garcia-Serres, Ricardo; Clémancey, Martin; Latour, Jean-Marc; Blondin, Geneviève

2018-01-19

Fe/S cluster biogenesis involves a complex machinery comprising several mitochondrial and cytosolic proteins. Fe/S cluster biosynthesis is closely intertwined with iron trafficking in the cell. Defects in Fe/S cluster elaboration result in severe diseases such as Friedreich ataxia. Deciphering this machinery is a challenge for the scientific community. Because iron is a key player, 57 Fe-Mössbauer spectroscopy is especially appropriate for the characterization of Fe species and monitoring the iron distribution. This minireview intends to illustrate how Mössbauer spectroscopy contributes to unravel steps in Fe/S cluster biogenesis. Studies were performed on isolated proteins that may be present in multiple protein complexes. Since a few decades, Mössbauer spectroscopy was also performed on whole cells or on isolated compartments such as mitochondria and vacuoles, affording an overview of the iron trafficking. This minireview aims at presenting selected applications of 57 Fe-Mössbauer spectroscopy to Fe/S cluster biogenesis.

Biogenesis of mitochondrial carrier proteins: molecular mechanisms of import into mitochondria.

PubMed

Ferramosca, Alessandra; Zara, Vincenzo

2013-03-01

Mitochondrial metabolite carriers are hydrophobic proteins which catalyze the flux of several charged or hydrophilic substrates across the inner membrane of mitochondria. These proteins, like most mitochondrial proteins, are nuclear encoded and after their synthesis in the cytosol are transported into the inner mitochondrial membrane. Most metabolite carriers, differently from other nuclear encoded mitochondrial proteins, are synthesized without a cleavable presequence and contain several, poorly characterized, internal targeting signals. However, an interesting aspect is the presence of a positively charged N-terminal presequence in a limited number of mitochondrial metabolite carriers. Over the last few years the molecular mechanisms of import of metabolite carrier proteins into mitochondria have been thoroughly investigated. This review summarizes the present knowledge and discusses recent advances on the import and sorting of mitochondrial metabolite carriers. Copyright © 2012 Elsevier B.V. All rights reserved.

DEMONSTRATION BULLETIN: BIOGENESIS SOIL WASHING TECHNOLOGY - BIOGENESIS

EPA Science Inventory

The BioGenesisSM soil washing technology was developed by BioGenesis Enterprises, Inc. to remove organic compounds from soil. The technology uses a proprietary solution (BioGenesisSM cleaner) to transfer organic compounds from the soil matrix to a liquid phase. BioGenesis claims...

Iron-sulfur cluster biogenesis in mammalian cells: new insights into the molecular mechanisms of cluster delivery

PubMed Central

Maio, Nunziata; Rouault, Tracey. A.

2014-01-01

Iron-sulfur (Fe-S) clusters are ancient, ubiquitous cofactors composed of iron and inorganic sulfur. The combination of the chemical reactivity of iron and sulfur, together with many variations of cluster composition, oxidation states and protein environments, enables Fe-S clusters to participate in numerous biological processes. Fe-S clusters are essential to redox catalysis in nitrogen fixation, mitochondrial respiration and photosynthesis, to regulatory sensing in key metabolic pathways (i. e. cellular iron homeostasis and oxidative stress response), and to the replication and maintenance of the nuclear genome. Fe-S cluster biogenesis is a multistep process that involves a complex sequence of catalyzed protein- protein interactions and coupled conformational changes between the components of several dedicated multimeric complexes. Intensive studies of the assembly process have clarified key points in the biogenesis of Fe-S proteins. However several critical questions still remain, such as: what is the role of frataxin? Why do some defects of Fe-S cluster biogenesis cause mitochondrial iron overload? How are specific Fe-S recipient proteins recognized in the process of Fe-S transfer? This review focuses on the basic steps of Fe-S cluster biogenesis, drawing attention to recent advances achieved on the identification of molecular features that guide selection of specific subsets of nascent Fe-S recipients by the cochaperone HSC20. Additionally, it outlines the distinctive phenotypes of human diseases due to mutations in the components of the basic pathway. PMID:25245479

Protective Effects of Myricetin on Acute Hypoxia-Induced Exercise Intolerance and Mitochondrial Impairments in Rats

PubMed Central

Zou, Dan; Liu, Peng; Chen, Ka; Xie, Qi; Liang, Xinyu; Bai, Qian; Zhou, Qicheng; Liu, Kai; Zhang, Ting; Zhu, Jundong; Mi, Mantian

2015-01-01

Purpose Exercise tolerance is impaired in hypoxia. The aim of this study was to evaluate the effects of myricetin, a dietary flavonoid compound widely found in fruits and vegetables, on acute hypoxia-induced exercise intolerance in vivo and in vitro. Methods Male rats were administered myricetin or vehicle for 7 days and subsequently spent 24 hours at a barometric pressure equivalent to 5000 m. Exercise capacity was then assessed through the run-to-fatigue procedure, and mitochondrial morphology in skeletal muscle cells was observed by transmission electron microscopy (TEM). The enzymatic activities of electron transfer complexes were analyzed using an enzyme-linked immuno-sorbent assay (ELISA). mtDNA was quantified by real-time-PCR. Mitochondrial membrane potential was measured by JC-1 staining. Protein expression was detected through western blotting, immunohistochemistry, and immunofluorescence. Results Myricetin supplementation significantly prevented the decline of run-to-fatigue time of rats in hypoxia, and attenuated acute hypoxia-induced mitochondrial impairment in skeletal muscle cells in vivo and in vitro by maintaining mitochondrial structure, mtDNA content, mitochondrial membrane potential, and activities of the respiratory chain complexes. Further studies showed that myricetin maintained mitochondrial biogenesis in skeletal muscle cells under hypoxic conditions by up-regulating the expressions of mitochondrial biogenesis-related regluators, in addition, AMP-activated protein kinase(AMPK) plays a crucial role in this process. Conclusions Myricetin may have important applications for improving physical performance under hypoxic environment, which may be attributed to the protective effect against mitochondrial impairment by maintaining mitochondrial biogenesis. PMID:25919288

Congenital sideroblastic anemia due to mutations in the mitochondrial HSP70 homologue HSPA9

PubMed Central

Schmitz-Abe, Klaus; Ciesielski, Szymon J.; Schmidt, Paul J.; Campagna, Dean R.; Rahimov, Fedik; Schilke, Brenda A.; Cuijpers, Marloes; Rieneck, Klaus; Lausen, Birgitte; Linenberger, Michael L.; Sendamarai, Anoop K.; Guo, Chaoshe; Hofmann, Inga; Newburger, Peter E.; Matthews, Dana; Shimamura, Akiko; Snijders, Pieter J. L. M.; Towne, Meghan C.; Niemeyer, Charlotte M.; Watson, Henry G.; Dziegiel, Morten H.; Heeney, Matthew M.; May, Alison; Bottomley, Sylvia S.; Swinkels, Dorine W.; Markianos, Kyriacos; Craig, Elizabeth A.

2015-01-01

The congenital sideroblastic anemias (CSAs) are relatively uncommon diseases characterized by defects in mitochondrial heme synthesis, iron-sulfur (Fe-S) cluster biogenesis, or protein synthesis. Here we demonstrate that mutations in HSPA9, a mitochondrial HSP70 homolog located in the chromosome 5q deletion syndrome 5q33 critical deletion interval and involved in mitochondrial Fe-S biogenesis, result in CSA inherited as an autosomal recessive trait. In a fraction of patients with just 1 severe loss-of-function allele, expression of the clinical phenotype is associated with a common coding single nucleotide polymorphism in trans that correlates with reduced messenger RNA expression and results in a pseudodominant pattern of inheritance. PMID:26491070

Synergistic interaction of fatty acids and oxysterols impairs mitochondrial function and limits liver adaptation during nafld progression.

PubMed

Bellanti, Francesco; Villani, Rosanna; Tamborra, Rosanna; Blonda, Maria; Iannelli, Giuseppina; di Bello, Giorgia; Facciorusso, Antonio; Poli, Giuseppe; Iuliano, Luigi; Avolio, Carlo; Vendemiale, Gianluigi; Serviddio, Gaetano

2018-05-01

The complete mechanism accounting for the progression from simple steatosis to steatohepatitis in nonalcoholic fatty liver disease (NAFLD) has not been elucidated. Lipotoxicity refers to cellular injury caused by hepatic free fatty acids (FFAs) and cholesterol accumulation. Excess cholesterol autoxidizes to oxysterols during oxidative stress conditions. We hypothesize that interaction of FAs and cholesterol derivatives may primarily impair mitochondrial function and affect biogenesis adaptation during NAFLD progression. We demonstrated that the accumulation of specific non-enzymatic oxysterols in the liver of animals fed high-fat+high-cholesterol diet induces mitochondrial damage and depletion of proteins of the respiratory chain complexes. When tested in vitro, 5α-cholestane-3β,5,6β-triol (triol) combined to FFAs was able to reduce respiration in isolated liver mitochondria, induced apoptosis in primary hepatocytes, and down-regulated transcription factors involved in mitochondrial biogenesis. Finally, a lower protein content in the mitochondrial respiratory chain complexes was observed in human non-alcoholic steatohepatitis. In conclusion, hepatic accumulation of FFAs and non-enzymatic oxysterols synergistically facilitates development and progression of NAFLD by impairing mitochondrial function, energy balance and biogenesis adaptation to chronic injury. Copyright © 2017. Published by Elsevier B.V.

Interaction between AIF and CHCHD4 Regulates Respiratory Chain Biogenesis.

PubMed

Hangen, Emilie; Féraud, Olivier; Lachkar, Sylvie; Mou, Haiwei; Doti, Nunzianna; Fimia, Gian Maria; Lam, Ngoc-Vy; Zhu, Changlian; Godin, Isabelle; Muller, Kevin; Chatzi, Afroditi; Nuebel, Esther; Ciccosanti, Fabiola; Flamant, Stéphane; Bénit, Paule; Perfettini, Jean-Luc; Sauvat, Allan; Bennaceur-Griscelli, Annelise; Ser-Le Roux, Karine; Gonin, Patrick; Tokatlidis, Kostas; Rustin, Pierre; Piacentini, Mauro; Ruvo, Menotti; Blomgren, Klas; Kroemer, Guido; Modjtahedi, Nazanine

2015-06-18

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein that, beyond its apoptotic function, is required for the normal expression of major respiratory chain complexes. Here we identified an AIF-interacting protein, CHCHD4, which is the central component of a redox-sensitive mitochondrial intermembrane space import machinery. Depletion or hypomorphic mutation of AIF caused a downregulation of CHCHD4 protein by diminishing its mitochondrial import. CHCHD4 depletion sufficed to induce a respiratory defect that mimicked that observed in AIF-deficient cells. CHCHD4 levels could be restored in AIF-deficient cells by enforcing its AIF-independent mitochondrial localization. This modified CHCHD4 protein reestablished respiratory function in AIF-deficient cells and enabled AIF-deficient embryoid bodies to undergo cavitation, a process of programmed cell death required for embryonic morphogenesis. These findings explain how AIF contributes to the biogenesis of respiratory chain complexes, and they establish an unexpected link between the vital function of AIF and the propensity of cells to undergo apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.

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

PubMed

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

2005-11-15

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

GPA protects the nigrostriatal dopamine system by enhancing mitochondrial function.

PubMed

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

2011-07-01

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

Distinct Pathways Mediate the Sorting of Tail-anchored Mitochondrial Outer Membrane Proteins

USDA-ARS?s Scientific Manuscript database

Little is known about the biogenesis of tail-anchored (TA) proteins localized to the mitochondrial outer membrane in plant cells. To address this issue, we screened all of the (>500) known and predicted TA proteins in Arabidopsis for those annotated, based on Gene Ontology, to possess mitochondrial...

Impaired mitochondrial Fe-S cluster biogenesis activates the DNA damage response through different signaling mediators.

PubMed

Pijuan, Jordi; María, Carlos; Herrero, Enrique; Bellí, Gemma

2015-12-15

Fe-S cluster biogenesis machinery is required for multiple DNA metabolism processes. In this work, we show that, in Saccharomyces cerevisiae, defects at different stages of the mitochondrial Fe-S cluster assembly machinery (ISC) result in increased spontaneous mutation rate and hyper-recombination, accompanied by an increment in Rad52-associated DNA repair foci and a higher phosphorylated state of γH2A histone, altogether supporting the presence of constitutive DNA lesions. Furthermore, ISC assembly machinery deficiency elicits a DNA damage response that upregulates ribonucleotide reductase activity by promoting the reduction of Sml1 levels and the cytosolic redistribution of Rnr2 and Rnr4 enzyme subunits. Depending on the impaired stage of the ISC machinery, different signaling pathway mediators contribute to such a response, converging on Dun1. Thus, cells lacking the glutaredoxin Grx5, which are compromised at the core ISC system, show Mec1- and Rad53-independent Dun1 activation, whereas both Mec1 and Chk1 are required when the non-core ISC member Iba57 is absent. Grx5-null cells exhibit a strong dependence on the error-free post-replication repair and the homologous recombination pathways, demonstrating that a DNA damage response needs to be activated upon ISC impairment to preserve cell viability. © 2015. Published by The Company of Biologists Ltd.

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

Short-Chain Fatty Acid Acetate Stimulates Adipogenesis and Mitochondrial Biogenesis via GPR43 in Brown Adipocytes.

PubMed

Hu, Jiamiao; Kyrou, Ioannis; Tan, Bee K; Dimitriadis, Georgios K; Ramanjaneya, Manjunath; Tripathi, Gyanendra; Patel, Vanlata; James, Sean; Kawan, Mohamed; Chen, Jing; Randeva, Harpal S

2016-05-01

Short-chain fatty acids play crucial roles in a range of physiological functions. However, the effects of short-chain fatty acids on brown adipose tissue have not been fully investigated. We examined the role of acetate, a short-chain fatty acid formed by fermentation in the gut, in the regulation of brown adipocyte metabolism. Our results show that acetate up-regulates adipocyte protein 2, peroxisomal proliferator-activated receptor-γ coactivator-1α, and uncoupling protein-1 expression and affects the morphological changes of brown adipocytes during adipogenesis. Moreover, an increase in mitochondrial biogenesis was observed after acetate treatment. Acetate also elicited the activation of ERK and cAMP response element-binding protein, and these responses were sensitive to G(i/o)-type G protein inactivator, Gβγ-subunit inhibitor, phospholipase C inhibitor, and MAPK kinase inhibitor, indicating a role for the G(i/o)βγ/phospholipase C/protein kinase C/MAPK kinase signaling pathway in these responses. These effects of acetate were mimicked by treatment with 4-chloro-α-(1-methylethyl)-N-2-thiazolylbenzeneacetamide, a synthetic G protein-coupled receptor 43 (GPR43) agonist and were impaired in GPR43 knockdown cells. Taken together, our results indicate that acetate may have important physiological roles in brown adipocytes through the activation of GPR43.

Integrating multiple aspects of mitochondrial dynamics in neurons: Age-related differences and dynamic changes in a chronic rotenone model

PubMed Central

Arnold, Beth; Cassady, Steven J.; Van Laar, Victor S.; Berman, Sarah B.

2010-01-01

Changes in dynamic properties of mitochondria are increasingly implicated in neurodegenerative diseases, particularly Parkinson’s disease (PD). Static changes in mitochondrial morphology, often under acutely toxic conditions, are commonly utilized as indicators of changes in mitochondrial fission and fusion. However, in neurons, mitochondrial fission and fusion occur in a dynamic system of axonal/dendritic transport, biogenesis and degradation, and thus, likely interact and change over time. We sought to explore this using a chronic neuronal model (nonlethal low-concentration rotenone over several weeks), examining distal neurites, which may give insight into the earliest changes occurring in PD. Using this model, in live primary neurons, we directly quantified mitochondrial fission, fusion, and transport over time and integrated multiple aspects of mitochondrial dynamics, including morphology and growth/mitophagy. We found that rates of mitochondrial fission and fusion change as neurons age. In addition, we found that chronic rotenone exposure initially increased the ratio of fusion to fission, but later, this was reversed. Surprisingly, despite changes in rates of fission and fusion, mitochondrial morphology was minimally affected, demonstrating that morphology can be an inaccurate indicator of fission/fusion changes. In addition, we found evidence of subcellular compartmentalization of compensatory changes, as mitochondrial density increased in distal neurites first, which may be important in PD, where pathology may begin distally. We propose that rotenone-induced early changes such as in mitochondrial fusion are compensatory, accompanied later by detrimental fission. As evidence, in a dopaminergic neuronal model, in which chronic rotenone caused loss of neurites before cell death (like PD pathology), inhibiting fission protected against the neurite loss. This suggests that aberrant mitochondrial dynamics may contribute to the earliest neuropathologic

Exercise-induced mitochondrial p53 repairs mtDNA mutations in mutator mice.

PubMed

Safdar, Adeel; Khrapko, Konstantin; Flynn, James M; Saleem, Ayesha; De Lisio, Michael; Johnston, Adam P W; Kratysberg, Yevgenya; Samjoo, Imtiaz A; Kitaoka, Yu; Ogborn, Daniel I; Little, Jonathan P; Raha, Sandeep; Parise, Gianni; Akhtar, Mahmood; Hettinga, Bart P; Rowe, Glenn C; Arany, Zoltan; Prolla, Tomas A; Tarnopolsky, Mark A

2016-01-01

Human genetic disorders and transgenic mouse models have shown that mitochondrial DNA (mtDNA) mutations and telomere dysfunction instigate the aging process. Epidemiologically, exercise is associated with greater life expectancy and reduced risk of chronic diseases. While the beneficial effects of exercise are well established, the molecular mechanisms instigating these observations remain unclear. Endurance exercise reduces mtDNA mutation burden, alleviates multisystem pathology, and increases lifespan of the mutator mice, with proofreading deficient mitochondrial polymerase gamma (POLG1). We report evidence for a POLG1-independent mtDNA repair pathway mediated by exercise, a surprising notion as POLG1 is canonically considered to be the sole mtDNA repair enzyme. Here, we show that the tumor suppressor protein p53 translocates to mitochondria and facilitates mtDNA mutation repair and mitochondrial biogenesis in response to endurance exercise. Indeed, in mutator mice with muscle-specific deletion of p53, exercise failed to prevent mtDNA mutations, induce mitochondrial biogenesis, preserve mitochondrial morphology, reverse sarcopenia, or mitigate premature mortality. Our data establish a new role for p53 in exercise-mediated maintenance of the mtDNA genome and present mitochondrially targeted p53 as a novel therapeutic modality for diseases of mitochondrial etiology.

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

Saxagliptin restores vascular mitochondrial exercise response in the Goto-Kakizaki rat.

PubMed

Keller, Amy C; Knaub, Leslie A; Miller, Matthew W; Birdsey, Nicholas; Klemm, Dwight J; Reusch, Jane E B

2015-02-01

Cardiovascular disease risk and all-cause mortality are largely predicted by physical fitness. Exercise stimulates vascular mitochondrial biogenesis through endothelial nitric oxide synthase (eNOS), sirtuins, and PPARγ coactivator 1α (PGC-1α), a response absent in diabetes and hypertension. We hypothesized that an agent regulating eNOS in the context of diabetes could reconstitute exercise-mediated signaling to mitochondrial biogenesis. Glucagon-like peptide 1 (GLP-1) stimulates eNOS and blood flow; we used saxagliptin, an inhibitor of GLP-1 degradation, to test whether vascular mitochondrial adaptation to exercise in diabetes could be restored. Goto-Kakizaki (GK) rats, a nonobese, type 2 diabetes model, and Wistar controls were exposed to an 8-day exercise intervention with or without saxagliptin (10 mg·kg·d). We evaluated the impact of exercise and saxagliptin on mitochondrial proteins and signaling pathways in aorta. Mitochondrial protein expression increased with exercise in the Wistar aorta and decreased or remained unchanged in the GK animals. GK rats treated with saxagliptin plus exercise showed increased expression of mitochondrial complexes, cytochrome c, eNOS, nNOS, PGC-1α, and UCP3 proteins. Notably, a 3-week saxagliptin plus exercise intervention significantly increased running time in the GK rats. These data suggest that saxagliptin restores vascular mitochondrial adaptation to exercise in a diabetic rodent model and may augment the impact of exercise on the vasculature.

Role of FAST Kinase Domains 3 (FASTKD3) in Post-transcriptional Regulation of Mitochondrial Gene Expression*

PubMed Central

Boehm, Erik; Zornoza, María; Jourdain, Alexis A.; Delmiro Magdalena, Aitor; García-Consuegra, Inés; Torres Merino, Rebeca; Orduña, Antonio; Martín, Miguel A.; Martinou, Jean-Claude; De la Fuente, Miguel A.; Simarro, María

2016-01-01

The Fas-activated serine/threonine kinase (FASTK) family of proteins has recently emerged as a central regulator of mitochondrial gene expression through the function of an unusual RNA-binding domain named RAP (for RNA-binding domain abundant in Apicomplexans), shared by all six members of the family. Here we describe the role of one of the less characterized members, FASTKD3, in mitochondrial RNA metabolism. First, we show that, in contrast to FASTK, FASTKD2, and FASTKD5, FASTKD3 does not localize in mitochondrial RNA granules, which are sites of processing and maturation of mtRNAs and ribosome biogenesis. Second, we generated FASTKD3 homozygous knock-out cell lines by homologous recombination and observed that the absence of FASTKD3 resulted in increased steady-state levels and half-lives of a subset of mature mitochondrial mRNAs: ND2, ND3, CYTB, COX2, and ATP8/6. No aberrant processing of RNA precursors was observed. Rescue experiments demonstrated that RAP domain is required for FASTKD3 function in mRNA stability. Besides, we describe that FASTKD3 is required for efficient COX1 mRNA translation without altering mRNA levels, which results in a decrease in the steady-state levels of COX1 protein. This finding is associated with reduced mitochondrial complex IV assembly and activity. Our observations suggest that the function of this family of proteins goes beyond RNA processing and ribosome assembly and includes RNA stability and translation regulation within mitochondria. PMID:27789713

Co-regulation of nuclear respiratory factor-1 by NFκB and CREB links LPS-induced inflammation to mitochondrial biogenesis

PubMed Central

Suliman, Hagir B.; Sweeney, Timothy E.; Withers, Crystal M.; Piantadosi, Claude A.

2010-01-01

The nuclear respiratory factor-1 (NRF1) gene is activated by lipopolysaccharide (LPS), which might reflect TLR4-mediated mitigation of cellular inflammatory damage via initiation of mitochondrial biogenesis. To test this hypothesis, we examined NRF1 promoter regulation by NFκB, and identified interspecies-conserved κB-responsive promoter and intronic elements in the NRF1 locus. In mice, activation of Nrf1 and its downstream target, Tfam, by Escherichia coli was contingent on NFκB, and in LPS-treated hepatocytes, NFκB served as an NRF1 enhancer element in conjunction with NFκB promoter binding. Unexpectedly, optimal NRF1 promoter activity after LPS also required binding by the energy-state-dependent transcription factor CREB. EMSA and ChIP assays confirmed p65 and CREB binding to the NRF1 promoter and p65 binding to intron 1. Functionality for both transcription factors was validated by gene-knockdown studies. LPS regulation of NRF1 led to mtDNA-encoded gene expression and expansion of mtDNA copy number. In cells expressing plasmid constructs containing the NRF-1 promoter and GFP, LPS-dependent reporter activity was abolished by cis-acting κB-element mutations, and nuclear accumulation of NFκB and CREB demonstrated dependence on mitochondrial H2O2. These findings indicate that TLR4-dependent NFκB and CREB activation co-regulate the NRF1 promoter with NFκB intronic enhancement and redox-regulated nuclear translocation, leading to downstream target-gene expression, and identify NRF-1 as an early-phase component of the host antibacterial defenses. PMID:20587593

A trypanosomal orthologue of an intermembrane space chaperone has a non-canonical function in biogenesis of the single mitochondrial inner membrane protein translocase.

PubMed

Wenger, Christoph; Oeljeklaus, Silke; Warscheid, Bettina; Schneider, André; Harsman, Anke

2017-08-01

Mitochondrial protein import is essential for Trypanosoma brucei across its life cycle and mediated by membrane-embedded heterooligomeric protein complexes, which mainly consist of trypanosomatid-specific subunits. However, trypanosomes contain orthologues of small Tim chaperones that escort hydrophobic proteins across the intermembrane space. Here we have experimentally analyzed three novel trypanosomal small Tim proteins, one of which contains only an incomplete Cx3C motif. RNAi-mediated ablation of TbERV1 shows that their import, as in other organisms, depends on the MIA pathway. Submitochondrial fractionation combined with immunoprecipitation and BN-PAGE reveals two pools of small Tim proteins: a soluble fraction forming 70 kDa complexes, consistent with hexamers and a second fraction that is tightly associated with the single trypanosomal TIM complex. RNAi-mediated ablation of the three proteins leads to a growth arrest and inhibits the formation of the TIM complex. In line with these findings, the changes in the mitochondrial proteome induced by ablation of one small Tim phenocopy the effects observed after ablation of TbTim17. Thus, the trypanosomal small Tims play an unexpected and essential role in the biogenesis of the single TIM complex, which for one of them is not linked to import of TbTim17.

Why translation counts for mitochondria - retrograde signalling links mitochondrial protein synthesis to mitochondrial biogenesis and cell proliferation.

PubMed

Battersby, Brendan J; Richter, Uwe

2013-10-01

Organelle biosynthesis is a key requirement for cell growth and division. The regulation of mitochondrial biosynthesis exhibits additional layers of complexity compared with that of other organelles because they contain their own genome and dedicated ribosomes. Maintaining these components requires gene expression to be coordinated between the nucleo-cytoplasmic compartment and mitochondria in order to monitor organelle homeostasis and to integrate the responses to the physiological and developmental demands of the cell. Surprisingly, the parameters that are used to monitor or count mitochondrial abundance are not known, nor are the signalling pathways. Inhibiting the translation on mito-ribosomes genetically or with antibiotics can impair cell proliferation and has been attributed to defects in aerobic energy metabolism, even though proliferating cells rely primarily on glycolysis to fuel their metabolic demands. However, a recent study indicates that mitochondrial translational stress and the rescue mechanisms that relieve this stress cause the defect in cell proliferation and occur before any impairment of oxidative phosphorylation. Therefore, the process of mitochondrial translation in itself appears to be an important checkpoint for the monitoring of mitochondrial homeostasis and might have a role in establishing mitochondrial abundance within a cell. This hypothesis article will explore the evidence supporting a role for mito-ribosomes and translation in a mitochondria-counting mechanism.

Transcriptome and Small RNA Deep Sequencing Reveals Deregulation of miRNA Biogenesis in Human Glioma

PubMed Central

Moore, Lynette M.; Kivinen, Virpi; Liu, Yuexin; Annala, Matti; Cogdell, David; Liu, Xiuping; Liu, Chang-Gong; Sawaya, Raymond; Yli-Harja, Olli; Shmulevich, Ilya; Fuller, Gregory N.; Zhang, Wei; Nykter, Matti

2013-01-01

Altered expression of oncogenic and tumor-suppressing microRNAs (miRNAs) is widely associated with tumorigenesis. However, the regulatory mechanisms underlying these alterations are poorly understood. We sought to shed light on the deregulation of miRNA biogenesis promoting the aberrant miRNA expression profiles identified in these tumors. Using sequencing technology to perform both whole-transcriptome and small RNA sequencing of glioma patient samples, we examined precursor and mature miRNAs to directly evaluate the miRNA maturation process, and interrogated expression profiles for genes involved in the major steps of miRNA biogenesis. We found that ratios of mature to precursor forms of a large number of miRNAs increased with the progression from normal brain to low-grade and then to high-grade gliomas. The expression levels of genes involved in each of the three major steps of miRNA biogenesis (nuclear processing, nucleo-cytoplasmic transport, and cytoplasmic processing) were systematically altered in glioma tissues. Survival analysis of an independent data set demonstrated that the alteration of genes involved in miRNA maturation correlates with survival in glioma patients. Direct quantification of miRNA maturation with deep sequencing demonstrated that deregulation of the miRNA biogenesis pathway is a hallmark for glioma genesis and progression. PMID:23007860

A Molecular Approach to Mitophagy and Mitochondrial Dynamics

PubMed Central

Yoo, Seung-Min; Jung, Yong-Keun

2018-01-01

Mitochondrial quality control systems are essential for the maintenance of functional mitochondria. At the organelle level, they include mitochondrial biogenesis, fusion and fission, to compensate for mitochondrial function, and mitophagy, for degrading damaged mitochondria. Specifically, in mitophagy, the target mitochondria are recognized by the autophagosomes and delivered to the lysosome for degradation. In this review, we describe the mechanisms of mitophagy and the factors that play an important role in this process. In particular, we focus on the roles of mitophagy adapters and receptors in the recognition of damaged mitochondria by autophagosomes. In addition, we also address a functional association of mitophagy with mitochondrial dynamics through the interaction of mitophagy adaptor and receptor proteins with mitochondrial fusion and fission proteins. PMID:29370689

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

Multifunctional Mitochondrial AAA Proteases

PubMed Central

Glynn, Steven E.

2017-01-01

Mitochondria perform numerous functions necessary for the survival of eukaryotic cells. These activities are coordinated by a diverse complement of proteins encoded in both the nuclear and mitochondrial genomes that must be properly organized and maintained. Misregulation of mitochondrial proteostasis impairs organellar function and can result in the development of severe human diseases. ATP-driven AAA+ proteins play crucial roles in preserving mitochondrial activity by removing and remodeling protein molecules in accordance with the needs of the cell. Two mitochondrial AAA proteases, i-AAA and m-AAA, are anchored to either face of the mitochondrial inner membrane, where they engage and process an array of substrates to impact protein biogenesis, quality control, and the regulation of key metabolic pathways. The functionality of these proteases is extended through multiple substrate-dependent modes of action, including complete degradation, partial processing, or dislocation from the membrane without proteolysis. This review discusses recent advances made toward elucidating the mechanisms of substrate recognition, handling, and degradation that allow these versatile proteases to control diverse activities in this multifunctional organelle. PMID:28589125

Multifunctional Mitochondrial AAA Proteases.

PubMed

Glynn, Steven E

2017-01-01

Mitochondria perform numerous functions necessary for the survival of eukaryotic cells. These activities are coordinated by a diverse complement of proteins encoded in both the nuclear and mitochondrial genomes that must be properly organized and maintained. Misregulation of mitochondrial proteostasis impairs organellar function and can result in the development of severe human diseases. ATP-driven AAA+ proteins play crucial roles in preserving mitochondrial activity by removing and remodeling protein molecules in accordance with the needs of the cell. Two mitochondrial AAA proteases, i-AAA and m-AAA, are anchored to either face of the mitochondrial inner membrane, where they engage and process an array of substrates to impact protein biogenesis, quality control, and the regulation of key metabolic pathways. The functionality of these proteases is extended through multiple substrate-dependent modes of action, including complete degradation, partial processing, or dislocation from the membrane without proteolysis. This review discusses recent advances made toward elucidating the mechanisms of substrate recognition, handling, and degradation that allow these versatile proteases to control diverse activities in this multifunctional organelle.

Mitochondrial fatty acid synthesis, fatty acids and mitochondrial physiology.

PubMed

Kastaniotis, Alexander J; Autio, Kaija J; Kerätär, Juha M; Monteuuis, Geoffray; Mäkelä, Anne M; Nair, Remya R; Pietikäinen, Laura P; Shvetsova, Antonina; Chen, Zhijun; Hiltunen, J Kalervo

2017-01-01

Mitochondria and fatty acids are tightly connected to a multiplicity of cellular processes that go far beyond mitochondrial fatty acid metabolism. In line with this view, there is hardly any common metabolic disorder that is not associated with disturbed mitochondrial lipid handling. Among other aspects of mitochondrial lipid metabolism, apparently all eukaryotes are capable of carrying out de novo fatty acid synthesis (FAS) in this cellular compartment in an acyl carrier protein (ACP)-dependent manner. The dual localization of FAS in eukaryotic cells raises the questions why eukaryotes have maintained the FAS in mitochondria in addition to the "classic" cytoplasmic FAS and what the products are that cannot be substituted by delivery of fatty acids of extramitochondrial origin. The current evidence indicates that mitochondrial FAS is essential for cellular respiration and mitochondrial biogenesis. Although both β-oxidation and FAS utilize thioester chemistry, CoA acts as acyl-group carrier in the breakdown pathway whereas ACP assumes this role in the synthetic direction. This arrangement metabolically separates these two pathways running towards opposite directions and prevents futile cycling. A role of this pathway in mitochondrial metabolic sensing has recently been proposed. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum. Copyright © 2016 Elsevier B.V. All rights reserved.

Fructose-Rich Diet Affects Mitochondrial DNA Damage and Repair in Rats.

PubMed

Cioffi, Federica; Senese, Rosalba; Lasala, Pasquale; Ziello, Angela; Mazzoli, Arianna; Crescenzo, Raffaella; Liverini, Giovanna; Lanni, Antonia; Goglia, Fernando; Iossa, Susanna

2017-03-24

Evidence indicates that many forms of fructose-induced metabolic disturbance are associated with oxidative stress and mitochondrial dysfunction. Mitochondria are prominent targets of oxidative damage; however, it is not clear whether mitochondrial DNA (mtDNA) damage and/or its lack of repair are events involved in metabolic disease resulting from a fructose-rich diet. In the present study, we evaluated the degree of oxidative damage to liver mtDNA and its repair, in addition to the state of oxidative stress and antioxidant defense in the liver of rats fed a high-fructose diet. We used male rats feeding on a high-fructose or control diet for eight weeks. Our results showed an increase in mtDNA damage in the liver of rats fed a high-fructose diet and this damage, as evaluated by the expression of DNA polymerase γ, was not repaired; in addition, the mtDNA copy number was found to be significantly reduced. A reduction in the mtDNA copy number is indicative of impaired mitochondrial biogenesis, as is the finding of a reduction in the expression of genes involved in mitochondrial biogenesis. In conclusion, a fructose-rich diet leads to mitochondrial and mtDNA damage, which consequently may have a role in liver dysfunction and metabolic diseases.

Saxagliptin Restores Vascular Mitochondrial Exercise Response in the Goto-Kakizaki Rat

PubMed Central

Keller, Amy C.; Knaub, Leslie A.; Miller, Matthew W.; Birdsey, Nicholas; Klemm, Dwight J.

2015-01-01

Abstract: Cardiovascular disease risk and all-cause mortality are largely predicted by physical fitness. Exercise stimulates vascular mitochondrial biogenesis through endothelial nitric oxide synthase (eNOS), sirtuins, and PPARγ coactivator 1α (PGC-1α), a response absent in diabetes and hypertension. We hypothesized that an agent regulating eNOS in the context of diabetes could reconstitute exercise-mediated signaling to mitochondrial biogenesis. Glucagon-like peptide 1 (GLP-1) stimulates eNOS and blood flow; we used saxagliptin, an inhibitor of GLP-1 degradation, to test whether vascular mitochondrial adaptation to exercise in diabetes could be restored. Goto-Kakizaki (GK) rats, a nonobese, type 2 diabetes model, and Wistar controls were exposed to an 8-day exercise intervention with or without saxagliptin (10 mg·kg−1·d−1). We evaluated the impact of exercise and saxagliptin on mitochondrial proteins and signaling pathways in aorta. Mitochondrial protein expression increased with exercise in the Wistar aorta and decreased or remained unchanged in the GK animals. GK rats treated with saxagliptin plus exercise showed increased expression of mitochondrial complexes, cytochrome c, eNOS, nNOS, PGC-1α, and UCP3 proteins. Notably, a 3-week saxagliptin plus exercise intervention significantly increased running time in the GK rats. These data suggest that saxagliptin restores vascular mitochondrial adaptation to exercise in a diabetic rodent model and may augment the impact of exercise on the vasculature. PMID:25264749

Mitochondrial ribosome assembly in health and disease

PubMed Central

De Silva, Dasmanthie; Tu, Ya-Ting; Amunts, Alexey; Fontanesi, Flavia; Barrientos, Antoni

2015-01-01

The ribosome is a structurally and functionally conserved macromolecular machine universally responsible for catalyzing protein synthesis. Within eukaryotic cells, mitochondria contain their own ribosomes (mitoribosomes), which synthesize a handful of proteins, all essential for the biogenesis of the oxidative phosphorylation system. High-resolution cryo-EM structures of the yeast, porcine and human mitoribosomal subunits and of the entire human mitoribosome have uncovered a wealth of new information to illustrate their evolutionary divergence from their bacterial ancestors and their adaptation to synthesis of highly hydrophobic membrane proteins. With such structural data becoming available, one of the most important remaining questions is that of the mitoribosome assembly pathway and factors involved. The regulation of mitoribosome biogenesis is paramount to mitochondrial respiration, and thus to cell viability, growth and differentiation. Moreover, mutations affecting the rRNA and protein components produce severe human mitochondrial disorders. Despite its biological and biomedical significance, knowledge on mitoribosome biogenesis and its deviations from the much-studied bacterial ribosome assembly processes is scarce, especially the order of rRNA processing and assembly events and the regulatory factors required to achieve fully functional particles. This article focuses on summarizing the current available information on mitoribosome assembly pathway, factors that form the mitoribosome assembly machinery, and the effect of defective mitoribosome assembly on human health. PMID:26030272

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

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

Increased Degradation Rates in the Components of the Mitochondrial Oxidative Phosphorylation Chain in the Cerebellum of Old Mice

PubMed Central

Popa-Wagner, Aurel; Sandu, Raluca E.; Cristin, Coman; Uzoni, Adriana; Welle, Kevin A.; Hryhorenko, Jennifer R.; Ghaemmaghami, Sina

2018-01-01

Brain structures differ in the magnitude of age-related neuron loss with the cerebellum being more affected. An underlying cause could be an age-related decline in mitochondrial bioenergetics. Successful aging of mitochondria reflects a balanced turnover of proteins involved in mitochondrial biogenesis and mitophagy. Thus, an imbalance in mitochondrial turnover can contribute to the diminution of cellular function seen during aging. Mitochondrial biogenesis and mitophagy are mediated by a set of proteins including MFN1, MFN2, OPA1, DRP1, FIS1 as well as DMN1l and DNM1, all of which are required for mitochondrial fission. Using N15 labeling, we report that the turnover rates for DMN1l and FIS1 go in opposite directions in the cerebellum of 22-month-old C57BL6j mice as compared to 3-month-old mice. Previous studies have reported decreased turnover rates for the mitochondrial respiratory complexes of aged rodents. In contrast, we found increased turnover rates for mitochondrial proteins of the oxidative phosphorylation chain in the aged mice as compared to young mice. Furthermore, the turnover rate of the components that are most affected by aging –complex III components (ubiquinol cytochrome C oxidoreductase) and complex IV components (cytochrome C oxidase)– was significantly increased in the senescent cerebellum. However, the turnover rates of proteins involved in mitophagy (i.e., the proteasomal and lysosomal degradation of damaged mitochondria) were not significantly altered with age. Overall, our results suggest that an age-related imbalance in the turnover rates of proteins involved in mitochondrial biogenesis and mitophagy (DMN1l, FIS1) in conjunction with an age-related imbalance in the turnover rates of proteins of the complexes III and IV of the electron transfer chain, might impair cerebellar mitochondrial bioenergetics in old mice. PMID:29503614

Copper supplementation restores cytochrome c oxidase assembly defect in a mitochondrial disease model of COA6 deficiency.

PubMed

Ghosh, Alok; Trivedi, Prachi P; Timbalia, Shrishiv A; Griffin, Aaron T; Rahn, Jennifer J; Chan, Sherine S L; Gohil, Vishal M

2014-07-01

Mitochondrial respiratory chain biogenesis is orchestrated by hundreds of assembly factors, many of which are yet to be discovered. Using an integrative approach based on clues from evolutionary history, protein localization and human genetics, we have identified a conserved mitochondrial protein, C1orf31/COA6, and shown its requirement for respiratory complex IV biogenesis in yeast, zebrafish and human cells. A recent next-generation sequencing study reported potential pathogenic mutations within the evolutionarily conserved Cx₉CxnCx₁₀C motif of COA6, implicating it in mitochondrial disease biology. Using yeast coa6Δ cells, we show that conserved residues in the motif, including the residue mutated in a patient with mitochondrial disease, are essential for COA6 function, thus confirming the pathogenicity of the patient mutation. Furthermore, we show that zebrafish embryos with zfcoa6 knockdown display reduced heart rate and cardiac developmental defects, recapitulating the observed pathology in the human mitochondrial disease patient who died of neonatal hypertrophic cardiomyopathy. The specific requirement of Coa6 for respiratory complex IV biogenesis, its intramitochondrial localization and the presence of the Cx₉CxnCx₁₀C motif suggested a role in mitochondrial copper metabolism. In support of this, we show that exogenous copper supplementation completely rescues respiratory and complex IV assembly defects in yeast coa6Δ cells. Taken together, our results establish an evolutionarily conserved role of Coa6 in complex IV assembly and support a causal role of the COA6 mutation in the human mitochondrial disease patient. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Biogenesis of the yeast cytochrome bc1 complex.

PubMed

Zara, Vincenzo; Conte, Laura; Trumpower, Bernard L

2009-01-01

The mitochondrial respiratory chain is composed of four different protein complexes that cooperate in electron transfer and proton pumping across the inner mitochondrial membrane. The cytochrome bc1 complex, or complex III, is a component of the mitochondrial respiratory chain. This review will focus on the biogenesis of the bc1 complex in the mitochondria of the yeast Saccharomyces cerevisiae. In wild type yeast mitochondrial membranes the major part of the cytochrome bc1 complex was found in association with one or two copies of the cytochrome c oxidase complex. The analysis of several yeast mutant strains in which single genes or pairs of genes encoding bc1 subunits had been deleted revealed the presence of a common set of bc1 sub-complexes. These sub-complexes are represented by the central core of the bc1 complex, consisting of cytochrome b bound to subunit 7 and subunit 8, by the two core proteins associated with each other, by the Rieske protein associated with subunit 9, and by those deriving from the unexpected interaction of each of the two core proteins with cytochrome c1. Furthermore, a higher molecular mass sub-complex is that composed of cytochrome b, cytochrome c1, core protein 1 and 2, subunit 6, subunit 7 and subunit 8. The identification and characterization of all these sub-complexes may help in defining the steps and the molecular events leading to bc1 assembly in yeast mitochondria.

SIRT1 is required for AMPK activation and the beneficial effects of resveratrol on mitochondrial function

PubMed Central

Price, Nathan L.; Gomes, Ana P.; Ling, Alvin J.Y.; Duarte, Filipe V.; Martin-Montalvo, Alejandro; North, Brian J.; Agarwal, Beamon; Ye, Lan; Ramadori, Giorgio; Teodoro, Joao S.; Hubbard, Basil P.; Varela, Ana T.; Davis, James G.; Varamini, Behzad; Hafner, Angela; Moaddel, Ruin; Rolo, Anabela P.; Coppari, Roberto; Palmeira, Carlos M.; de Cabo, Rafael; Baur, Joseph A.; Sinclair, David A.

2012-01-01

SUMMARY Resveratrol induces mitochondrial biogenesis and protects against metabolic decline but whether SIRT1 mediates these benefits is the subject of debate. To circumvent the developmental defects of germ-line SIRT1 knockouts, we have developed the first inducible system that permits whole-body deletion of SIRT1 in adult mice. Mice treated with a moderate dose of resveratrol showed increased mitochondrial biogenesis and function, AMPK activation and increased NAD+ levels in skeletal muscle, whereas SIRT1 knockouts displayed none of these benefits. A mouse overexpressing SIRT1 mimicked these effects. A high dose of resveratrol activated AMPK in a SIRT1-independent manner, demonstrating that resveratrol dosage is a critical factor. Importantly, at both doses of resveratrol no improvements in mitochondrial function were observed in animals lacking SIRT1. Together these data indicate that SIRT1 plays an essential role in the ability of moderate doses of resveratrol to stimulate AMPK and improve mitochondrial function both in vitro and in vivo. PMID:22560220

Dealing with an Unconventional Genetic Code in  Mitochondria: The Biogenesis and Pathogenic  Defects of the 5-Formylcytosine Modification in  Mitochondrial tRNAMet.

PubMed

Van Haute, Lindsey; Powell, Christopher A; Minczuk, Michal

2017-03-02

Human mitochondria contain their own genome, which uses an unconventional genetic code. In addition to the standard AUG methionine codon, the single mitochondrial tRNA Methionine (mt-tRNAMet) also recognises AUA during translation initiation and elongation. Post-transcriptional modifications of tRNAs are important for structure, stability, correct folding and aminoacylation as well as decoding. The unique 5-formylcytosine (f5C) modification of position 34 in mt-tRNAMet has been long postulated to be crucial for decoding of unconventional methionine codons and efficient mitochondrial translation. However, the enzymes responsible for the formation of mitochondrial f5C have been identified only recently. The first step of the f5C pathway consists of methylation of cytosine by NSUN3. This is followed by further oxidation by ABH1. Here, we review the role of f5C, the latest breakthroughs in our understanding of the biogenesis of this unique mitochondrial tRNA modification and its involvement in human disease.

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.

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

Principal Aspects Regarding the Maintenance of Mammalian Mitochondrial Genome Integrity.

PubMed

Vasileiou, Panagiotis V S; Mourouzis, Iordanis; Pantos, Constantinos

2017-08-22

Mitochondria have emerged as key players regarding cellular homeostasis not only due to their contribution regarding energy production through oxidative phosphorylation, but also due to their involvement in signaling, ion regulation, and programmed cell death. Indeed, current knowledge supports the notion that mitochondrial dysfunction is a hallmark in the pathogenesis of various diseases. Mitochondrial biogenesis and function require the coordinated action of two genomes: nuclear and mitochondrial. Unfortunately, both intrinsic and environmental genotoxic insults constantly threaten the integrity of nuclear as well as mitochondrial DNA. Despite the extensive research that has been made regarding nuclear genome instability, the importance of mitochondrial genome integrity has only recently begun to be elucidated. The specific architecture and repair mechanisms of mitochondrial DNA, as well as the dynamic behavior that mitochondria exert regarding fusion, fission, and autophagy participate in mitochondrial genome stability, and therefore, cell homeostasis.

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

Valproate Attenuates Nitroglycerin-Induced Trigeminovascular Activation by Preserving Mitochondrial Function in a Rat Model of Migraine

PubMed Central

Li, Ruxian; Liu, Yushuang; Chen, Nan; Zhang, Yitong; Song, Ge; Zhang, Zhongling

2016-01-01

Background Migraine is a chronic disease that interferes with life quality and work productivity. Valproate shows protective effects against migraine, yet the underlying mechanisms are unclear. This study aimed to evaluate the potential effect of valproate on migraine using a rat model of nitroglycerin-induced trigeminovascular activation, as well as to explore the underlying mechanism. Material/Methods Intraperitoneal injection of nitroglycerin was conducted to induce trigeminovascular activation in rats. To explore the protective effect of valproate, a low dose (100 mg/kg) or a high dose (200 mg/kg) of valproate was intraperitoneally injected into rats, and then the levels of 5-hydroxytryptamine and nitric oxide in the peripheral blood were examined. The mtDNA copy number and the protein levels of peroxisome proliferator-activated receptor-γ coactivator 1α, mitochondrial transcription factor A, and peroxisome proliferator-activated receptor-γ in the spinal trigeminal nucleus were detected to evaluate the biogenesis of mitochondria. The mitochondrial energy metabolism was determined by the mitochondrial membrane potential and the levels of adenosine triphosphate, cytochrome C oxidase, and reactive oxygen species. Results Valproate attenuated nitroglycerin-induced trigeminovascular activation in rats, with reduced scratching behavior and restored 5-hydroxytryptamine and nitric oxide levels. Moreover, the mitochondrial energy metabolism and the biogenesis of mitochondria were preserved by valproate in nitroglycerin-treated rats. Conclusions The protective effect of valproate against migraine may be achieved through the modulation of mitochondrial biogenesis and function. Our study provides evidence for the potential use of valproate in the treatment of migraine. PMID:27618395

Valproate Attenuates Nitroglycerin-Induced Trigeminovascular Activation by Preserving Mitochondrial Function in a Rat Model of Migraine.

PubMed

Li, Ruxian; Liu, Yushuang; Chen, Nan; Zhang, Yitong; Song, Ge; Zhang, Zhongling

2016-09-12

BACKGROUND Migraine is a chronic disease that interferes with life quality and work productivity. Valproate shows protective effects against migraine, yet the underlying mechanisms are unclear. This study aimed to evaluate the potential effect of valproate on migraine using a rat model of nitroglycerin-induced trigeminovascular activation, as well as to explore the underlying mechanism. MATERIAL AND METHODS Intraperitoneal injection of nitroglycerin was conducted to induce trigeminovascular activation in rats. To explore the protective effect of valproate, a low dose (100 mg/kg) or a high dose (200 mg/kg) of valproate was intraperitoneally injected into rats, and then the levels of 5-hydroxytryptamine and nitric oxide in the peripheral blood were examined. The mtDNA copy number and the protein levels of peroxisome proliferator-activated receptor-γ coactivator 1α, mitochondrial transcription factor A, and peroxisome proliferator-activated receptor-γ in the spinal trigeminal nucleus were detected to evaluate the biogenesis of mitochondria. The mitochondrial energy metabolism was determined by the mitochondrial membrane potential and the levels of adenosine triphosphate, cytochrome C oxidase, and reactive oxygen species. RESULTS Valproate attenuated nitroglycerin-induced trigeminovascular activation in rats, with reduced scratching behavior and restored 5-hydroxytryptamine and nitric oxide levels. Moreover, the mitochondrial energy metabolism and the biogenesis of mitochondria were preserved by valproate in nitroglycerin-treated rats. CONCLUSIONS The protective effect of valproate against migraine may be achieved through the modulation of mitochondrial biogenesis and function. Our study provides evidence for the potential use of valproate in the treatment of migraine.

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-06-01

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

Requirement of FADD, NEMO, and BAX/BAK for Aberrant Mitochondrial Function in Tumor Necrosis Factor Alpha-Induced Necrosis▿

PubMed Central

Irrinki, Krishna M.; Mallilankaraman, Karthik; Thapa, Roshan J.; Chandramoorthy, Harish C.; Smith, Frank J.; Jog, Neelakshi R.; Gandhirajan, Rajesh Kumar; Kelsen, Steven G.; Houser, Steven R.; May, Michael J.; Balachandran, Siddharth; Madesh, Muniswamy

2011-01-01

Necroptosis represents a form of alternative programmed cell death that is dependent on the kinase RIP1. RIP1-dependent necroptotic death manifests as increased reactive oxygen species (ROS) production in mitochondria and is accompanied by loss of ATP biogenesis and eventual dissipation of mitochondrial membrane potential. Here, we show that tumor necrosis factor alpha (TNF-α)-induced necroptosis requires the adaptor proteins FADD and NEMO. FADD was found to mediate formation of the TNF-α-induced pronecrotic RIP1-RIP3 kinase complex, whereas the IκB Kinase (IKK) subunit NEMO appears to function downstream of RIP1-RIP3. Interestingly, loss of RelA potentiated TNF-α-dependent necroptosis, indicating that NEMO regulates necroptosis independently of NF-κB. Using both pharmacologic and genetic approaches, we demonstrate that the overexpression of antioxidants alleviates ROS elevation and necroptosis. Finally, elimination of BAX and BAK or overexpression of Bcl-xL protects cells from necroptosis at a later step. These findings provide evidence that mitochondria play an amplifying role in inflammation-induced necroptosis. PMID:21746883

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.

Targeting Pin1 by inhibitor API-1 regulates microRNA biogenesis and suppresses hepatocellular carcinoma development.

PubMed

Pu, Wenchen; Li, Jiao; Zheng, Yuanyuan; Shen, Xianyan; Fan, Xin; Zhou, Jian-Kang; He, Juan; Deng, Yulan; Liu, Xuesha; Wang, Chun; Yang, Shengyong; Chen, Qiang; Liu, Lunxu; Zhang, Guolin; Wei, Yu-Quan; Peng, Yong

2018-01-30

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide, but there are few effective treatments. Aberrant microRNA (miRNA) biogenesis is correlated with HCC development. We previously demonstrated that peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) participates in miRNA biogenesis and is a potential HCC treatment target. However, how Pin1 modulates miRNA biogenesis remains obscure. Here, we present in vivo evidence that Pin1 overexpression is directly linked to the development of HCC. Administration with the Pin1 inhibitor (API-1), a specific small molecule targeting Pin1 peptidyl-prolyl isomerase domain and inhibiting Pin1 cis-trans isomerizing activity, suppresses in vitro cell proliferation and migration of HCC cells. But API-1-induced Pin1 inhibition is insensitive to HCC cells with low Pin1 expression and/or low exportin-5 (XPO5) phosphorylation. Mechanistically, Pin1 recognizes and isomerizes the phosphorylated serine-proline motif of phosphorylated XPO5 and passivates phosphorylated XPO5. Pin1 inhibition by API-1 maintains the active conformation of phosphorylated XPO5 and restores XPO5-driven precursor miRNA nuclear-to-cytoplasm export, activating anticancer miRNA biogenesis and leading to both in vitro HCC suppression and HCC suppression in xenograft mice. Experimental evidence suggests that Pin1 inhibition by API-1 up-regulates miRNA biogenesis by retaining active XPO5 conformation and suppresses HCC development, revealing the mechanism of Pin1-mediated miRNA biogenesis and unequivocally supporting API-1 as a drug candidate for HCC therapy, especially for Pin1-overexpressing, extracellular signal-regulated kinase-activated HCC. (Hepatology 2018). © 2018 by the American Association for the Study of Liver Diseases.

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.

Failed upregulation of TFAM protein and mitochondrial DNA in oxidatively deficient fibers of chronic obstructive pulmonary disease locomotor muscle.

PubMed

Konokhova, Yana; Spendiff, Sally; Jagoe, R Thomas; Aare, Sudhakar; Kapchinsky, Sophia; MacMillan, Norah J; Rozakis, Paul; Picard, Martin; Aubertin-Leheudre, Mylène; Pion, Charlotte H; Bourbeau, Jean; Hepple, Russell T; Taivassalo, Tanja

2016-01-01

Low mitochondrial content and oxidative capacity are well-established features of locomotor muscle dysfunction, a prevalent and debilitating systemic occurrence in patients with chronic obstructive pulmonary disease (COPD). Although the exact cause is not firmly established, physical inactivity and oxidative stress are among the proposed underlying mechanisms. Here, we assess the impact of COPD pathophysiology on mitochondrial DNA (mtDNA) integrity, biogenesis, and cellular oxidative capacity in locomotor muscle of COPD patients and healthy controls. We hypothesized that the high oxidative stress environment of COPD muscle would yield a higher presence of deletion-containing mtDNA and oxidative-deficient fibers and impaired capacity for mitochondrial biogenesis. Vastus lateralis biopsies were analyzed from 29 COPD patients and 19 healthy age-matched controls for the presence of mtDNA deletions, levels of oxidatively damaged DNA, mtDNA copy number, and regulators of mitochondrial biogenesis as well the proportion of oxidative-deficient fibers (detected histologically as cytochrome c oxidase-deficient, succinate dehydrogenase positive (COX(-)/SDH(+) )). Additionally, mtDNA copy number and mitochondrial transcription factor A (TFAM) content were measured in laser captured COX(-)SDH(+) and normal single fibers of both COPD and controls. Compared to controls, COPD muscle exhibited significantly higher levels of oxidatively damaged DNA (8-hydroxy-2-deoxyguanosine (8-OHdG) levels = 387 ± 41 vs. 258 ± 21 pg/mL) and higher prevalence of mtDNA deletions (74 vs. 15 % of subjects in each group), which was accompanied by a higher abundance of oxidative-deficient fibers (8.0 ± 2.1 vs. 1.5 ± 0.4 %). Interestingly, COPD patients with mtDNA deletions had higher levels of 8-OHdG (457 ± 46 pg/mL) and longer smoking history (66.3 ± 7.5 years) than patients without deletions (197 ± 29 pg/mL; 38.0 ± 7.3 years). Transcript levels of

The presequence pathway is involved in protein sorting to the mitochondrial outer membrane.

PubMed

Wenz, Lena-Sophie; Opaliński, Lukasz; Schuler, Max-Hinderk; Ellenrieder, Lars; Ieva, Raffaele; Böttinger, Lena; Qiu, Jian; van der Laan, Martin; Wiedemann, Nils; Guiard, Bernard; Pfanner, Nikolaus; Becker, Thomas

2014-06-01

The mitochondrial outer membrane contains integral α-helical and β-barrel proteins that are imported from the cytosol. The machineries importing β-barrel proteins have been identified, however, different views exist on the import of α-helical proteins. It has been reported that the biogenesis of Om45, the most abundant signal-anchored protein, does not depend on proteinaceous components, but involves direct insertion into the outer membrane. We show that import of Om45 occurs via the translocase of the outer membrane and the presequence translocase of the inner membrane. Assembly of Om45 in the outer membrane involves the MIM machinery. Om45 thus follows a new mitochondrial biogenesis pathway that uses elements of the presequence import pathway to direct a protein to the outer membrane. © 2014 The Authors.

Principal Aspects Regarding the Maintenance of Mammalian Mitochondrial Genome Integrity

PubMed Central

Vasileiou, Panagiotis V. S.; Mourouzis, Iordanis; Pantos, Constantinos

2017-01-01

Mitochondria have emerged as key players regarding cellular homeostasis not only due to their contribution regarding energy production through oxidative phosphorylation, but also due to their involvement in signaling, ion regulation, and programmed cell death. Indeed, current knowledge supports the notion that mitochondrial dysfunction is a hallmark in the pathogenesis of various diseases. Mitochondrial biogenesis and function require the coordinated action of two genomes: nuclear and mitochondrial. Unfortunately, both intrinsic and environmental genotoxic insults constantly threaten the integrity of nuclear as well as mitochondrial DNA. Despite the extensive research that has been made regarding nuclear genome instability, the importance of mitochondrial genome integrity has only recently begun to be elucidated. The specific architecture and repair mechanisms of mitochondrial DNA, as well as the dynamic behavior that mitochondria exert regarding fusion, fission, and autophagy participate in mitochondrial genome stability, and therefore, cell homeostasis. PMID:28829360

Estrogen receptor-β in mitochondria: implications for mitochondrial bioenergetics and tumorigenesis.

PubMed

Liao, Tien-Ling; Tzeng, Chii-Ruey; Yu, Chao-Lan; Wang, Yi-Pei; Kao, Shu-Huei

2015-09-01

Estrogen enhances mitochondrial function by enhancing mitochondrial biogenesis and sustaining mitochondrial energy-transducing capacity. Shifts in mitochondrial bioenergetic pathways from oxidative phosphorylation to glycolysis have been hypothesized to be involved in estrogen-induced tumorigenesis. Studies have shown that mitochondria are an important target of estrogen. Estrogen receptor-β (ERβ) has been shown to localize to mitochondria in a ligand-dependent or -independent manner and can affect mitochondrial bioenergetics and anti-apoptotic signaling. However, the functional role of mitochondrial ERβ in tumorigenesis remains unclear. Clinical studies of ERβ-related tumorigenesis have shown that ERβ stimulates mitochondrial metabolism to meet the high energy demands of processes such as cell proliferation, cell survival, and transformation. Thus, in elucidating the precise role of mitochondrial ERβ in cell transformation and tumorigenesis, it will be particularly valuable to explore new approaches for the development of medical treatments targeting mitochondrial ERβ-mediated mitochondrial function and preventing apoptosis. © 2015 New York Academy of Sciences.

Mitochondrial redox system, dynamics, and dysfunction in lung inflammaging and COPD.

PubMed

Lerner, Chad A; Sundar, Isaac K; Rahman, Irfan

2016-12-01

Myriad forms of endogenous and environmental stress disrupt mitochondrial function by impacting critical processes in mitochondrial homeostasis, such as mitochondrial redox system, oxidative phosphorylation, biogenesis, and mitophagy. External stressors that interfere with the steady state activity of mitochondrial functions are generally associated with an increase in reactive oxygen species, inflammatory response, and induction of cellular senescence (inflammaging) potentially via mitochondrial damage associated molecular patterns (DAMPS). Many of these are the key events in the pathogenesis of chronic obstructive pulmonary disease (COPD) and its exacerbations. In this review, we highlight the primary mitochondrial quality control mechanisms that are influenced by oxidative stress/redox system, including role of mitochondria during inflammation and cellular senescence, and how mitochondrial dysfunction contributes to the pathogenesis of COPD and its exacerbations via pathogenic stimuli. Copyright © 2016 Elsevier Ltd. All rights reserved.

Regulated Cell Death of Lymphoma Cells after Graded Mitochondrial Damage is Differentially Affected by Drugs Targeting Cell Stress Responses.

PubMed

Lombardo, Tomás; Folgar, Martín Gil; Salaverry, Luciana; Rey-Roldán, Estela; Alvarez, Elida M; Carreras, María C; Kornblihtt, Laura; Blanco, Guillermo A

2018-05-01

Collapse of the mitochondrial membrane potential (MMP) is often considered the initiation of regulated cell death (RCD). Carbonyl cyanide 3-chlorophenylhydrazone (CCCP) is an uncoupler of the electron transport chain (ETC) that facilitates the translocation of protons into the mitochondrial matrix leading to the collapse of the MMP. Several cell stress responses such as mitophagy, mitochondrial biogenesis and the ubiquitin proteasome system may differentially contribute to restrain the initiation of RCD depending on the extent of mitochondrial damage. We induced graded mitochondrial damage after collapse of MMP with the mitochondrial uncoupler CCCP in Burkitt's lymphoma cells, and we evaluated the effect of several drugs targeting cell stress responses over RCD at 72 hr, using a multiparametric flow cytometry approach. CCCP caused collapse of MMP after 30 min., massive mitochondrial fission, oxidative stress and increased mitophagy within the 5-15 μM low-dose range (LDR) of CCCP. Within the 20-50 μM high-dose range (HDR), CCCP caused lysosomal destabilization and rupture, thus precluding mitophagy and autophagy. Cell death after 72 hr was below 20%, with increased mitochondrial mass (MM). The inhibitors of mitophagy 3-(2,4-dichloro-5-methoxyphenyl)-2,3-dihydro-2-thioxo-4(1H)-quinazolinone (Mdivi-1) and vincristine (VCR) increased cell death from CCCP within the LDR, while valproic acid (an inducer of mitochondrial biogenesis) also increased MM and cell death within the LDR. The proteasome inhibitor, MG132, increased cell death only in the HDR. Doxycycline, an antibiotic that disrupts mitochondrial biogenesis, had no effect on cell survival, while iodoacetamide, an inhibitor of glycolysis, increased cell death at the HDR. We conclude that mitophagy influenced RCD of lymphoma cells after MMP collapse by CCCP only within the LDR, while proteasome activity and glycolysis contributed to survival in the HDR under extensive mitochondria and lysosome damage. © 2017

Mitochondrial Dysfunction in Cancer

PubMed Central

Boland, Michelle L.; Chourasia, Aparajita H.; Macleod, Kay F.

2013-01-01

A mechanistic understanding of how mitochondrial dysfunction contributes to cell growth and tumorigenesis is emerging beyond Warburg as an area of research that is under-explored in terms of its significance for clinical management of cancer. Work discussed in this review focuses less on the Warburg effect and more on mitochondria and how dysfunctional mitochondria modulate cell cycle, gene expression, metabolism, cell viability, and other established aspects of cell growth and stress responses. There is increasing evidence that key oncogenes and tumor suppressors modulate mitochondrial dynamics through important signaling pathways and that mitochondrial mass and function vary between tumors and individuals but the significance of these events for cancer are not fully appreciated. We explore the interplay between key molecules involved in mitochondrial fission and fusion and in apoptosis, as well as in mitophagy, biogenesis, and spatial dynamics of mitochondria and consider how these distinct mechanisms are coordinated in response to physiological stresses such as hypoxia and nutrient deprivation. Importantly, we examine how deregulation of these processes in cancer has knock on effects for cell proliferation and growth. We define major forms of mitochondrial dysfunction and address the extent to which the functional consequences of such dysfunction can be determined and exploited for cancer diagnosis and treatment. PMID:24350057

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.

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

PubMed

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

2017-04-01

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

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

PubMed Central

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

2012-01-01

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

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

Translation and Assembly of Radiolabeled Mitochondrial DNA-Encoded Protein Subunits from Cultured Cells and Isolated Mitochondria.

PubMed

Formosa, Luke E; Hofer, Annette; Tischner, Christin; Wenz, Tina; Ryan, Michael T

2016-01-01

In higher eukaryotes, the mitochondrial electron transport chain consists of five multi-subunit membrane complexes responsible for the generation of cellular ATP. Of these, four complexes are under dual genetic control as they contain subunits encoded by both the mitochondrial and nuclear genomes, thereby adding another layer of complexity to the puzzle of respiratory complex biogenesis. These subunits must be synthesized and assembled in a coordinated manner in order to ensure correct biogenesis of different respiratory complexes. Here, we describe techniques to (1) specifically radiolabel proteins encoded by mtDNA to monitor the rate of synthesis using pulse labeling methods, and (2) analyze the stability, assembly, and turnover of subunits using pulse-chase methods in cultured cells and isolated mitochondria.

Hippocampal mutant APP and amyloid beta-induced cognitive decline, dendritic spine loss, defective autophagy, mitophagy and mitochondrial abnormalities in a mouse model of Alzheimer's disease.

PubMed

Manczak, Maria; Kandimalla, Ramesh; Yin, Xiangling; Reddy, P Hemachandra

2018-04-15

The purpose of our study was to determine the toxic effects of hippocampal mutant APP and amyloid beta (Aβ) in 12-month-old APP transgenic mice. Using rotarod and Morris water maze tests, immunoblotting and immunofluorescence, Golgi-cox staining and transmission electron microscopy, we assessed cognitive behavior, protein levels of synaptic, autophagy, mitophagy, mitochondrial dynamics, biogenesis, dendritic protein MAP2 and quantified dendritic spines and mitochondrial number and length in 12-month-old APP mice that express Swedish mutation. Mitochondrial function was assessed by measuring the levels of hydrogen peroxide, lipid peroxidation, cytochrome c oxidase activity and mitochondrial ATP. Morris water maze and rotarod tests revealed that hippocampal learning and memory and motor learning and coordination were impaired in APP mice relative to wild-type (WT) mice. Increased levels of mitochondrial fission proteins, Drp1 and Fis1 and decreased levels of fusion (Mfn1, Mfn2 and Opa1) biogenesis (PGC1α, NRF1, NRF2 and TFAM), autophagy (ATG5 and LC3BI, LC3BII), mitophagy (PINK1 and TERT), synaptic (synaptophysin and PSD95) and dendritic (MAP2) proteins were found in 12-month-old APP mice relative to age-matched non-transgenic WT mice. Golgi-cox staining analysis revealed that dendritic spines are significantly reduced. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in APP mice. These findings suggest that hippocampal accumulation of mutant APP and Aβ is responsible for abnormal mitochondrial dynamics and defective biogenesis, reduced MAP2, autophagy, mitophagy and synaptic proteins and reduced dendritic spines and hippocampal-based learning and memory impairments, and mitochondrial structural and functional changes in 12-month-old APP mice.

Sequential Actions of SIRT1-RELB-SIRT3 Coordinate Nuclear-Mitochondrial Communication during Immunometabolic Adaptation to Acute Inflammation and Sepsis*

PubMed Central

Liu, Tie Fu; Vachharajani, Vidula; Millet, Patrick; Bharadwaj, Manish S.; Molina, Anthony J.; McCall, Charles E.

2015-01-01

We reported that NAD+-dependent SIRT1, RELB, and SIRT6 nuclear proteins in monocytes regulate a switch from the glycolysis-dependent acute inflammatory response to fatty acid oxidation-dependent sepsis adaptation. We also found that disrupting SIRT1 activity during adaptation restores immunometabolic homeostasis and rescues septic mice from death. Here, we show that nuclear SIRT1 guides RELB to differentially induce SIRT3 expression and also increases mitochondrial biogenesis, which alters bioenergetics during sepsis adaptation. We constructed this concept using TLR4-stimulated THP1 human promonocytes, a model that mimics the initiation and adaptation stages of sepsis. Following increased expression, mitochondrial SIRT3 deacetylase activates the rate-limiting tricarboxylic acid cycle (TCA) isocitrate dehydrogenase 2 and superoxide dismutase 2, concomitant with increases in citrate synthase activity. Mitochondrial oxygen consumption rate increases early and decreases during adaptation, parallel with modifications to membrane depolarization, ATP generation, and production of mitochondrial superoxide and whole cell hydrogen peroxide. Evidence of SIRT1-RELB induction of mitochondrial biogenesis included increases in mitochondrial mass, mitochondrial-to-nuclear DNA ratios, and both nuclear and mitochondrial encoded proteins. We confirmed the SIRT-RELB-SIRT3 adaptation link to mitochondrial bioenergetics in both TLR4-stimulated normal and sepsis-adapted human blood monocytes and mouse splenocytes. We also found that SIRT1 inhibition ex vivo reversed the sepsis-induced changes in bioenergetics. PMID:25404738

The life of plant mitochondrial complex I.

PubMed

Braun, Hans-Peter; Binder, Stefan; Brennicke, Axel; Eubel, Holger; Fernie, Alisdair R; Finkemeier, Iris; Klodmann, Jennifer; König, Ann-Christine; Kühn, Kristina; Meyer, Etienne; Obata, Toshihiro; Schwarzländer, Markus; Takenaka, Mizuki; Zehrmann, Anja

2014-11-01

The mitochondrial NADH dehydrogenase complex (complex I) of the respiratory chain has several remarkable features in plants: (i) particularly many of its subunits are encoded by the mitochondrial genome, (ii) its mitochondrial transcripts undergo extensive maturation processes (e.g. RNA editing, trans-splicing), (iii) its assembly follows unique routes, (iv) it includes an additional functional domain which contains carbonic anhydrases and (v) it is, indirectly, involved in photosynthesis. Comprising about 50 distinct protein subunits, complex I of plants is very large. However, an even larger number of proteins are required to synthesize these subunits and assemble the enzyme complex. This review aims to follow the complete "life cycle" of plant complex I from various molecular perspectives. We provide arguments that complex I represents an ideal model system for studying the interplay of respiration and photosynthesis, the cooperation of mitochondria and the nucleus during organelle biogenesis and the evolution of the mitochondrial oxidative phosphorylation system. Copyright © 2014 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

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

PubMed

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

2018-03-17

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

Age associated low mitochondrial biogenesis may be explained by lack of response of PGC-1α to exercise training.

PubMed

Derbré, Frederic; Gomez-Cabrera, Mari Carmen; Nascimento, Ana Lucia; Sanchis-Gomar, Fabian; Martinez-Bello, Vladimir Essau; Tresguerres, Jesus A F; Fuentes, Teresa; Gratas-Delamarche, Arlette; Monsalve, Maria; Viña, Jose

2012-06-01

Low mitochondriogenesis is critical to explain loss of muscle function in aging and in the development of frailty. The aim of this work was to explain the mechanism by which mitochondriogenesis is decreased in aging and to determine to which extent it may be prevented by exercise training. We used aged rats and compared them with peroxisome proliferator-activated receptor-γ coactivator-1α deleted mice (PGC-1α KO). PGC-1α KO mice showed a significant decrease in the mitochondriogenic pathway in muscle. In aged rats, we found a loss of exercise-induced expression of PGC-1α, nuclear respiratory factor-1 (NRF-1), and of cytochrome C. Thus muscle mitochondriogenesis, which is activated by exercise training in young animals, is not in aged or PGC-1α KO ones. Other stimuli to increase PGC-1α synthesis apart from exercise training, namely cold induction or thyroid hormone treatment, were effective in young rats but not in aged ones. To sum up, the low mitochondrial biogenesis associated with aging may be due to the lack of response of PGC-1α to different stimuli. Aged rats behave as PGC-1α KO mice. Results reported here highlight the role of PGC-1α in the loss of mitochondriogenesis associated with aging and point to this important transcriptional coactivator as a target for pharmacological interventions to prevent age-associated sarcopenia.

Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics

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

Miyamoto, Yuki; Eguchi, Takahiro; Kawahara, Kazuko

Myelin-forming glial cells undergo dynamic morphological changes in order to produce mature myelin sheaths with multiple layers. In the central nervous system (CNS), oligodendrocytes differentiate to insulate neuronal axons with myelin sheaths. Myelin sheaths play a key role in homeostasis of the nervous system, but their related disorders lead not only to dismyelination and repeated demyelination but also to severe neuropathies. Hereditary hypomyelinating leukodystrophies (HLDs) are a group of such diseases affecting oligodendrocytes and are often caused by missense mutations of the respective responsible genes. Despite increasing identification of gene mutations through advanced nucleotide sequencing technology, studies on the relationshipsmore » between gene mutations and their effects on cellular and subcellular aberrance have not followed at the same rapid pace. In this study, we report that an HLD4-associated (Asp-29-to-Gly) mutant of mitochondrial heat shock 60-kDa protein 1 (HSPD1) causes short-length morphologies and increases the numbers of mitochondria due to their aberrant fission and fusion cycles. In experiments using a fluorescent dye probe, this mutation decreases the mitochondrial membrane potential. Also, mitochondria accumulate in perinuclear regions. HLD4-associated HSPD1 mutant blunts mitochondrial dynamics, probably resulting in oligodendrocyte malfunction. This study constitutes a first finding concerning the relationship between disease-associated HSPD1 mutation and mitochondrial dynamics, which may be similar to the relationship between another disease-associated HSPD1 mutation (MitCHAP-60 disease) and aberrant mitochondrial dynamics. - Highlights: • The HLD4 mutant of HSPD1 decreases mitochondrial fission frequency. • The HLD4 mutant decreases mitochondrial fusion frequency. • Mitochondria harboring the HLD4 mutant exhibit slow motility. • The HLD4 mutant of HSPD1 decreases mitochondrial membrane potential. • HLD4-related

Purple sweet potato color attenuates domoic acid-induced cognitive deficits by promoting estrogen receptor-α-mediated mitochondrial biogenesis signaling in mice.

PubMed

Lu, Jun; Wu, Dong-Mei; Zheng, Yuan-Lin; Hu, Bin; Cheng, Wei; Zhang, Zi-Feng

2012-02-01

Recent findings suggest that endoplasmic reticulum stress may be involved in the pathogenesis of domoic acid-induced neurodegeneration. Purple sweet potato color, a class of naturally occurring anthocyanins, has beneficial health and biological effects. Recent studies have also shown that anthocyanins have estrogenic activity and can enhance estrogen receptor-α expression. In this study, we evaluated the effect of purple sweet potato color on cognitive deficits induced by hippocampal mitochondrial dysfunction in domoic acid-treated mice and explored the potential mechanisms underlying this effect. Our results showed that the oral administration of purple sweet potato color to domoic acid-treated mice significantly improved their behavioral performance in a step-through passive avoidance task and a Morris water maze task. These improvements were mediated, at least in part, by a stimulation of estrogen receptor-α-mediated mitochondrial biogenesis signaling and by decreases in the expression of p47phox and gp91phox. Decreases in reactive oxygen species and protein carbonylation were also observed, along with a blockade of the endoplasmic reticulum stress pathway. Furthermore, purple sweet potato color significantly suppressed endoplasmic reticulum stress-induced apoptosis, which prevented neuron loss and restored the expression of memory-related proteins. However, knockdown of estrogen receptor-α using short hairpin RNA only partially blocked the neuroprotective effects of purple sweet potato color in the hippocampus of mice cotreated with purple sweet potato color and domoic acid, indicating that purple sweet potato color acts through multiple pathways. These results suggest that purple sweet potato color could be a possible candidate for the prevention and treatment of cognitive deficits in excitotoxic and other brain disorders. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

Ginsenoside Rg3 attenuates sepsis-induced injury and mitochondrial dysfunction in liver via AMPK-mediated autophagy flux.

PubMed

Xing, Wei; Yang, Lei; Peng, Yue; Wang, Qianlu; Gao, Min; Yang, Mingshi; Xiao, Xianzhong

2017-08-31

Sepsis-led mitochondrial dysfunction has become a critical pathophysiological procedure in sepsis. Since ginsenosides have been applied in the treatment of mitochondrial dysfunction, ginsenoside Rg3 was employed to study its effects on the mitochondrial dysfunction induced by sepsis. The apoptosis rate, oxygen consumption rate (OCR), reactive oxygen species (ROS), antioxidant glutathione (GSH) pools, and mitochondrial transmembrane potential (MTP) were determined in LPS-induced sepsis hepatocytes treated with different concentrations of Rg3. Then, the protein expression levels of mitochondrial biogenesis related transcription factors, autophagy-related proteins, and AMP-activated protein kinase (AMPK) signal pathway related proteins were determined by Western blotting in both in vitro and in vivo sepsis models. Rg3 shows functions of promotion of OCR, attenuation of ROS, and maintenance of GSH pools, and its conjugating activity in the in vitro sepsis models. Rg3-treated cells were observed to have a higher MTP value compared with the LPS only induced cells. Moreover, Rg3 treatment can inhibit mitochondrial dysfunction via increasing the protein expression levels of mitochondrial biogenesis related transcription factors. Rg3 treatment has the function of inhibitor of apoptosis of human primary hepatocytes, and Rg3 can up-regulate the autophagy-related proteins and activate AMPK signal pathway in sepsis models. Meanwhile, the mitochondrial protective function exerted by Rg3 decreased after the autophagy inhibitors or AMPK inhibitor treatment in LPS-induced human primary hepatocytes. Rg3 can improve mitochondrial dysfunction by regulating autophagy in mitochondria via activating the AMPK signal pathway, thus protecting cell and organ injuries caused by sepsis. © 2017 The Author(s).

Afzelin ameliorates D‐galactosamine and lipopolysaccharide‐induced fulminant hepatic failure by modulating mitochondrial quality control and dynamics

PubMed Central

Lee, Sang‐Bin; Kang, Jung‐Woo; Kim, So‐Jin; Ahn, Jongmin; Kim, Jinwoong

2016-01-01

Background and Purpose Fulminant hepatic failure (FHF) is a fatal clinical syndrome that results in excessive inflammation and hepatocyte death. Mitochondrial dysfunction is considered to be a possible mechanism of FHF. Afzelin, a flavonol glycoside found in Houttuynia cordata Thunberg, has anti‐inflammatory and antioxidant properties. The present study elucidated the cytoprotective mechanisms of afzelin against D‐galactosamine (GalN)/LPS induced FHF, particularly focusing on mitochondrial quality control and dynamics. Experimental Approach Mice were administered afzelin i.p. 1 h before receiving GalN (800 mg·kg−1)/LPS (40 μg·kg−1), and they were then killed 5 h after GalN/LPS treatment. Key Results Afzelin improved the survival rate and reduced the serum levels of alanine aminotransferase and pro‐inflammatory cytokines in GalN/LPS‐treated mice. Afzelin attenuated the mitochondrial damage, as indicated by diminished mitochondrial swelling and mitochondrial glutamate dehydrogenase activity in GalN/LPS‐treated mice. Afzelin enhanced mitochondrial biogenesis, as indicated by increased levels of PPAR‐γ coactivator 1α, nuclear respiratory factor 1 and mitochondrial transcription factor A. Afzelin also decreased the level of mitophagy‐related proteins, parkin and PTEN‐induced putative kinase 1. Furthermore, while GalN/LPS significantly increased the level of fission‐related protein, dynamin‐related protein 1, and decreased the level of fusion‐related protein, mitofusin 2; these effects were attenuated by afzelin. Conclusions and Implications Our findings demonstrated that afzelin protects against GalN/LPS‐induced liver injury by enhancing mitochondrial biogenesis, suppressing excessive mitophagy and balancing mitochondrial dynamics. PMID:27861739

SIRT1 Activation by Resveratrol Alleviates Cardiac Dysfunction via Mitochondrial Regulation in Diabetic Cardiomyopathy Mice.

PubMed

Ma, Sai; Feng, Jing; Zhang, Ran; Chen, Jiangwei; Han, Dong; Li, Xiang; Yang, Bo; Li, Xiujuan; Fan, Miaomiao; Li, Congye; Tian, Zuhong; Wang, Yabin; Cao, Feng

2017-01-01

Diabetic cardiomyopathy (DCM) is a major threat for diabetic patients. Silent information regulator 1 (SIRT1) has a regulatory effect on mitochondrial dynamics, which is associated with DCM pathological changes. Our study aims to investigate whether resveratrol, a SRIT1 activator, could exert a protective effect against DCM. Cardiac-specific SIRT1 knockout (SIRT1 KO ) mice were generated using Cre-loxP system. SIRT1 KO mice displayed symptoms of DCM, including cardiac hypertrophy and dysfunction, insulin resistance, and abnormal glucose metabolism. DCM and SIRT1 KO hearts showed impaired mitochondrial biogenesis and function, while SIRT1 activation by resveratrol reversed this in DCM mice. High glucose caused increased apoptosis, impaired mitochondrial biogenesis, and function in cardiomyocytes, which was alleviated by resveratrol. SIRT1 deletion by both SIRT1 KO and shRNA abolished the beneficial effects of resveratrol. Furthermore, the function of SIRT1 is mediated via the deacetylation effect on peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), thus inducing increased expression of nuclear respiratory factor 1 (NRF-1), NRF-2, estrogen-related receptor-α (ERR-α), and mitochondrial transcription factor A (TFAM). Cardiac deletion of SIRT1 caused phenotypes resembling DCM. Activation of SIRT1 by resveratrol ameliorated cardiac injuries in DCM through PGC-1α-mediated mitochondrial regulation. Collectively, SIRT1 may serve as a potential therapeutic target for DCM.

Vulnerable Parkin Loss-of-Function Drosophila Dopaminergic Neurons Have Advanced Mitochondrial Aging, Mitochondrial Network Loss and Transiently Reduced Autophagosome Recruitment.

PubMed

Cackovic, Juliana; Gutierrez-Luke, Susana; Call, Gerald B; Juba, Amber; O'Brien, Stephanie; Jun, Charles H; Buhlman, Lori M

2018-01-01

Selective degeneration of substantia nigra dopaminergic (DA) neurons is a hallmark pathology of familial Parkinson's disease (PD). While the mechanism of degeneration is elusive, abnormalities in mitochondrial function and turnover are strongly implicated. An Autosomal Recessive-Juvenile Parkinsonism (AR-JP) Drosophila melanogaster model exhibits DA neurodegeneration as well as aberrant mitochondrial dynamics and function. Disruptions in mitophagy have been observed in parkin loss-of-function models, and changes in mitochondrial respiration have been reported in patient fibroblasts. Whether loss of parkin causes selective DA neurodegeneration in vivo as a result of lost or decreased mitophagy is unknown. This study employs the use of fluorescent constructs expressed in Drosophila DA neurons that are functionally homologous to those of the mammalian substantia nigra. We provide evidence that degenerating DA neurons in parkin loss-of-function mutant flies have advanced mitochondrial aging, and that mitochondrial networks are fragmented and contain swollen organelles. We also found that mitophagy initiation is decreased in park ( Drosophila parkin/PARK2 ortholog) homozygous mutants, but autophagosome formation is unaffected, and mitochondrial network volumes are decreased. As the fly ages, autophagosome recruitment becomes similar to control, while mitochondria continue to show signs of damage, and climbing deficits persist. Interestingly, aberrant mitochondrial morphology, aging and mitophagy initiation were not observed in DA neurons that do not degenerate. Our results suggest that parkin is important for mitochondrial homeostasis in vulnerable Drosophila DA neurons, and that loss of parkin-mediated mitophagy may play a role in degeneration of relevant DA neurons or motor deficits in this model.

Quantifying small molecule phenotypic effects using mitochondrial morpho-functional fingerprinting and machine learning.

PubMed

Blanchet, Lionel; Smeitink, Jan A M; van Emst-de Vries, Sjenet E; Vogels, Caroline; Pellegrini, Mina; Jonckheere, An I; Rodenburg, Richard J T; Buydens, Lutgarde M C; Beyrath, Julien; Willems, Peter H G M; Koopman, Werner J H

2015-01-26

In primary fibroblasts from Leigh Syndrome (LS) patients, isolated mitochondrial complex I deficiency is associated with increased reactive oxygen species levels and mitochondrial morpho-functional changes. Empirical evidence suggests these aberrations constitute linked therapeutic targets for small chemical molecules. However, the latter generally induce multiple subtle effects, meaning that in vitro potency analysis or single-parameter high-throughput cell screening are of limited use to identify these molecules. We combine automated image quantification and artificial intelligence to discriminate between primary fibroblasts of a healthy individual and a LS patient based upon their mitochondrial morpho-functional phenotype. We then evaluate the effects of newly developed Trolox variants in LS patient cells. This revealed that Trolox ornithylamide hydrochloride best counterbalanced mitochondrial morpho-functional aberrations, effectively scavenged ROS and increased the maximal activity of mitochondrial complexes I, IV and citrate synthase. Our results suggest that Trolox-derived antioxidants are promising candidates in therapy development for human mitochondrial disorders.

Quantifying small molecule phenotypic effects using mitochondrial morpho-functional fingerprinting and machine learning

NASA Astrophysics Data System (ADS)

Blanchet, Lionel; Smeitink, Jan A. M.; van Emst-de Vries, Sjenet E.; Vogels, Caroline; Pellegrini, Mina; Jonckheere, An I.; Rodenburg, Richard J. T.; Buydens, Lutgarde M. C.; Beyrath, Julien; Willems, Peter H. G. M.; Koopman, Werner J. H.

2015-01-01

In primary fibroblasts from Leigh Syndrome (LS) patients, isolated mitochondrial complex I deficiency is associated with increased reactive oxygen species levels and mitochondrial morpho-functional changes. Empirical evidence suggests these aberrations constitute linked therapeutic targets for small chemical molecules. However, the latter generally induce multiple subtle effects, meaning that in vitro potency analysis or single-parameter high-throughput cell screening are of limited use to identify these molecules. We combine automated image quantification and artificial intelligence to discriminate between primary fibroblasts of a healthy individual and a LS patient based upon their mitochondrial morpho-functional phenotype. We then evaluate the effects of newly developed Trolox variants in LS patient cells. This revealed that Trolox ornithylamide hydrochloride best counterbalanced mitochondrial morpho-functional aberrations, effectively scavenged ROS and increased the maximal activity of mitochondrial complexes I, IV and citrate synthase. Our results suggest that Trolox-derived antioxidants are promising candidates in therapy development for human mitochondrial disorders.

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

PubMed

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

2014-09-01

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

Mutant APP and Amyloid beta-induced defective autophagy, mitophagy, mitochondrial structural and functional changes and synaptic damage in hippocampal neurons from Alzheimer's disease.

PubMed

Reddy, P Hemachandra; Yin, XiangLin; Manczak, Maria; Kumar, Subodh; Jangampalli Adi, Pradeepkiran; Vijayan, Murali; Reddy, Arubala P

2018-04-25

The purpose of our study was to determine the toxic effects of hippocampal mutant APP and amyloid beta (Aβ) in human mutant APP (mAPP) cDNA transfected with primary mouse hippocampal neurons (HT22). Hippocampal tissues are the best source of studying learning and memory functions in patients with Alzheimer's disease (AD) and healthy controls. However, investigating immortalized hippocampal neurons that express AD proteins provide an excellent opportunity for drug testing. Using quantitative RT-PCR, immunoblotting & immunofluorescence, and transmission electron microscopy, we assessed mRNA and protein levels of synaptic, autophagy, mitophagy, mitochondrial dynamics, biogenesis, dendritic protein MAP2, and assessed mitochondrial number and length in mAPP-HT22 cells that express Swedish/Indiana mutations. Mitochondrial function was assessed by measuring the levels of hydrogen peroxide, lipid peroxidation, cytochrome c oxidase activity and mitochondrial ATP. Increased levels of mRNA and protein levels of mitochondrial fission genes, Drp1 and Fis1 and decreased levels fusion (Mfn1, Mfn2 and Opa1) biogenesis (PGC1α, NRF1, NRF2 & TFAM), autophagy (ATG5 & LC3BI, LC3BII), mitophagy (PINK1 & TERT, BCL2 & BNIPBL), synaptic (synaptophysin & PSD95) and dendritic (MAP2) genes were found in mAPP-HT22 cells relative to WT-HT22 cells. Cell survival was significantly reduced mAPP-HT22 cells. GTPase-Dp1 enzymatic activity was increased in mAPP-HT22 cells. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in mAPP-HT22 cells. These findings suggest that hippocampal accumulation of mutant APP and Aβ is responsible for abnormal mitochondrial dynamics and defective biogenesis, reduced MAP2, autophagy, mitophagy and synaptic proteins & reduced dendritic spines and mitochondrial structural and functional changes in mutant APP hippocampal cells. These observations strongly suggest that accumulation of mAPP and A�

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

PubMed

Liu, Jiankang

2008-01-01

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

Distinct Pathways Mediate the Sorting of Tail-anchored Mitochondrial Outer Membrane Proteins

USDA-ARS?s Scientific Manuscript database

Little is known about the biogenesis of tail-anchored (TA) proteins localized to the mitochondrial outer membrane in plant cells. To address this issue, we screened all of the (>600) known and predicted TA proteins in Arabidopsis thaliana for those annotated, based on Gene Ontology, to possess mitoc...

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

RNA silencing of mitochondrial m-Nfs1 reduces Fe-S enzyme activity both in mitochondria and cytosol of mammalian cells.

PubMed

Fosset, Cédric; Chauveau, Marie-Jeanne; Guillon, Blanche; Canal, Frédéric; Drapier, Jean-Claude; Bouton, Cécile

2006-09-01

In prokaryotes and yeast, the general mechanism of biogenesis of iron-sulfur (Fe-S) clusters involves activities of several proteins among which IscS and Nfs1p provide, through cysteine desulfuration, elemental sulfide for Fe-S core formation. Although these proteins have been well characterized, the role of their mammalian homolog in Fe-S cluster biogenesis has never been evaluated. We report here the first functional study that implicates the putative cysteine desulfurase m-Nfs1 in the biogenesis of both mitochondrial and cytosolic mammalian Fe-S proteins. Depletion of m-Nfs1 in cultured fibroblasts through small interfering RNA-based gene silencing significantly inhibited the activities of mitochondrial NADH-ubiquinone oxidoreductase (complex I) and succinate-ubiquinone oxidoreductase (complex II) of the respiratory chain, as well as aconitase of the Krebs cycle, with no alteration in their protein levels. Activity of cytosolic xanthine oxidase, which holds a [2Fe-2S] cluster, was also specifically reduced, and iron-regulatory protein-1 was converted from its [4Fe-4S] aconitase form to its apo- or RNA-binding form. Reduction of Fe-S enzyme activities occurred earlier and more markedly in the cytosol than in mitochondria, suggesting that there is a mechanism that primarily dedicates m-Nfs1 to the biogenesis of mitochondrial Fe-S clusters in order to maintain cell survival. Finally, depletion of m-Nfs1, which conferred on apo-IRP-1 a high affinity for ferritin mRNA, was associated with the down-regulation of the iron storage protein ferritin.

Poly(ADP-Ribose) Polymerase 1 (PARP-1) Regulates Ribosomal Biogenesis in Drosophila Nucleoli

PubMed Central

Boamah, Ernest K.; Kotova, Elena; Garabedian, Mikael; Jarnik, Michael; Tulin, Alexei V.

2012-01-01

Poly(ADP-ribose) polymerase 1 (PARP1), a nuclear protein, utilizes NAD to synthesize poly(AD-Pribose) (pADPr), resulting in both automodification and the modification of acceptor proteins. Substantial amounts of PARP1 and pADPr (up to 50%) are localized to the nucleolus, a subnuclear organelle known as a region for ribosome biogenesis and maturation. At present, the functional significance of PARP1 protein inside the nucleolus remains unclear. Using PARP1 mutants, we investigated the function of PARP1, pADPr, and PARP1-interacting proteins in the maintenance of nucleolus structure and functions. Our analysis shows that disruption of PARP1 enzymatic activity caused nucleolar disintegration and aberrant localization of nucleolar-specific proteins. Additionally, PARP1 mutants have increased accumulation of rRNA intermediates and a decrease in ribosome levels. Together, our data suggests that PARP1 enzymatic activity is required for targeting nucleolar proteins to the proximity of precursor rRNA; hence, PARP1 controls precursor rRNA processing, post-transcriptional modification, and pre-ribosome assembly. Based on these findings, we propose a model that explains how PARP1 activity impacts nucleolar functions and, consequently, ribosomal biogenesis. PMID:22242017

Anaplastic Thyroid Carcinoma: A ceRNA Analysis Pointed to a Crosstalk between SOX2, TP53, and microRNA Biogenesis

PubMed Central

Carina, Valeria; Tomasello, Laura; Pitrone, Maria; Baiamonte, Concetta; Amato, Marco Calogero

2015-01-01

It has been suggested that cancer stem cells (CSC) may play a central role in oncogenesis, especially in undifferentiated tumours. Anaplastic thyroid carcinoma (ATC) has characteristics suggestive of a tumour enriched in CSC. Previous studies suggested that the stem cell factor SOX2 has a preeminent hierarchical role in determining the characteristics of stem cells in SW1736 ATC cell line. In detail, silencing SOX2 in SW1736 is able to suppress the expression of the stem markers analysed, strongly sensitizing the line to treatment with chemotherapeutic agents. Therefore, in order to further investigate the role of SOX2 in ATC, a competing endogenous RNA (ceRNA) analysis was conducted in order to isolate new functional partners of SOX2. Among the interactors, of particular interest are genes involved in the biogenesis of miRNAs (DICER1, RNASEN, and EIF2C2), in the control cell cycle (TP53, CCND1), and in mitochondrial activity (COX8A). The data suggest that stemness, microRNA biogenesis and functions, p53 regulatory network, cyclin D1, and cell cycle control, together with mitochondrial activity, might be coregulated. PMID:25705224

PARP10 (ARTD10) modulates mitochondrial function

PubMed Central

Nagy, Lilla; Vida, András; Kis, Gréta; Brunyánszki, Attila; Antal, Miklós; Lüscher, Bernhard; Bai, Péter

2018-01-01

Poly(ADP-ribose) polymerase (PARP)10 is a PARP family member that performs mono-ADP-ribosylation of target proteins. Recent studies have linked PARP10 to metabolic processes and metabolic regulators that prompted us to assess whether PARP10 influences mitochondrial oxidative metabolism. The depletion of PARP10 by specific shRNAs increased mitochondrial oxidative capacity in cellular models of breast, cervical, colorectal and exocrine pancreas cancer. Upon silencing of PARP10, mitochondrial superoxide production decreased in line with increased expression of antioxidant genes pointing out lower oxidative stress upon PARP10 silencing. Improved mitochondrial oxidative capacity coincided with increased AMPK activation. The silencing of PARP10 in MCF7 and CaCo2 cells decreased the proliferation rate that correlated with increased expression of anti-Warburg enzymes (Foxo1, PGC-1α, IDH2 and fumarase). By analyzing an online database we showed that lower PARP10 expression increases survival in gastric cancer. Furthermore, PARP10 expression decreased upon fasting, a condition that is characterized by increases in mitochondrial biogenesis. Finally, lower PARP10 expression is associated with increased fatty acid oxidation. PMID:29293500

AtSufE is an essential activator of plastidic and mitochondrial desulfurases in Arabidopsis

PubMed Central

Xu, Xiang Ming; Møller, Simon Geir

2006-01-01

Iron–sulfur (Fe–S) clusters are vital prosthetic groups for Fe–S proteins involved in fundamental processes such as electron transfer, metabolism, sensing and signaling. In plants, sulfur (SUF) protein-mediated Fe–S cluster biogenesis involves iron acquisition and sulfur mobilization, processes suggested to be plastidic. Here we have shown that AtSufE in Arabidopsis rescues growth defects in SufE-deficient Escherichia coli. In contrast to other SUF proteins, AtSufE localizes to plastids and mitochondria interacting with the plastidic AtSufS and mitochondrial AtNifS1 cysteine desulfurases. AtSufE activates AtSufS and AtNifS1 cysteine desulfurization, and AtSufE activity restoration in either plastids or mitochondria is not sufficient to rescue embryo lethality in AtSufE loss-of-function mutants. AtSufE overexpression induces AtSufS and AtNifS1 expression, which in turn leads to elevated cysteine desulfurization activity, chlorosis and retarded development. Our data demonstrate that plastidic and mitochondrial Fe–S cluster biogenesis shares a common, essential component, and that AtSufE acts as an activator of plastidic and mitochondrial desulfurases in Arabidopsis. PMID:16437155

Mitochondrial Proteome Studies in Seeds during Germination

PubMed Central

Czarna, Malgorzata; Kolodziejczak, Marta; Janska, Hanna

2016-01-01

Seed germination is considered to be one of the most critical phases in the plant life cycle, establishing the next generation of a plant species. It is an energy-demanding process that requires functioning mitochondria. One of the earliest events of seed germination is progressive development of structurally simple and metabolically quiescent promitochondria into fully active and cristae-containing mitochondria, known as mitochondrial biogenesis. This is a complex and tightly regulated process, which is accompanied by sequential and dynamic gene expression, protein synthesis, and post-translational modifications. The aim of this review is to give a comprehensive summary of seed mitochondrial proteome studies during germination of various plant model organisms. We describe different gel-based and gel-free proteomic approaches used to characterize mitochondrial proteomes of germinating seeds as well as challenges and limitations of these proteomic studies. Furthermore, the dynamic changes in the abundance of the mitochondrial proteomes of germinating seeds are illustrated, highlighting numerous mitochondrial proteins involved in respiration, tricarboxycylic acid (TCA) cycle, metabolism, import, and stress response as potentially important for seed germination. We then review seed mitochondrial protein carbonylation, phosphorylation, and S-nitrosylation as well as discuss the possible link between these post-translational modifications (PTMs) and the regulation of seed germination. PMID:28248229

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.

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.

Mitochondrial genome-maintaining activity of mouse mitochondrial transcription factor A and its transcript isoform in Saccharomyces cerevisiae.

PubMed

Yoon, Young Geol; Koob, Michael D; Yoo, Young Hyun

2011-09-15

Mitochondrial transcription factor A (Tfam) binds to and organizes mitochondrial DNA (mtDNA) genome into a mitochondrial nucleoid (mt-nucleoid) structure, which is necessary for mtDNA transcription and maintenance. Here, we demonstrate the mtDNA-organizing activity of mouse Tfam and its transcript isoform (Tfam(iso)), which has a smaller high-mobility group (HMG)-box1 domain, using a yeast model system that contains a deletion of the yeast homolog of mouse Tfam protein, Abf2p. When the mouse Tfam genes were introduced into the ABF2 locus of yeast genome, the corresponding mouse proteins, Tfam and Tfam(iso), can functionally replace the yeast Abf2p and support mtDNA maintenance and mitochondrial biogenesis in yeast. Growth properties, mtDNA content and mitochondrial protein levels of genes encoded in the mtDNA were comparable in the strains expressing mouse proteins and the wild-type yeast strain, indicating that the proteins have robust mtDNA-maintaining and -expressing function in yeast mitochondria. These results imply that the mtDNA-organizing activities of the mouse mt-nucleoid proteins are structurally and evolutionary conserved, thus they can maintain the mtDNA of distantly related and distinctively different species, such as yeast. Copyright © 2011 Elsevier B.V. All rights reserved.

Overexpression of the Mitochondrial T3 Receptor p43 Induces a Shift in Skeletal Muscle Fiber Types

PubMed Central

Casas, François; Pessemesse, Laurence; Grandemange, Stéphanie; Seyer, Pascal; Gueguen, Naïg; Baris, Olivier; Lepourry, Laurence; Cabello, Gérard; Wrutniak-Cabello, Chantal

2008-01-01

In previous studies, we have characterized a new hormonal pathway involving a mitochondrial T3 receptor (p43) acting as a mitochondrial transcription factor and consequently stimulating mitochondrial activity and mitochondrial biogenesis. We have established the involvement of this T3 pathway in the regulation of in vitro myoblast differentiation.We have generated mice overexpressing p43 under control of the human α-skeletal actin promoter. In agreement with the previous characterization of this promoter, northern-blot and western-blot experiments confirmed that after birth p43 was specifically overexpressed in skeletal muscle. As expected from in vitro studies, in 2-month old mice, p43 overexpression increased mitochondrial genes expression and mitochondrial biogenesis as attested by the increase of mitochondrial mass and mt-DNA copy number. In addition, transgenic mice had a body temperature 0.8°C higher than control ones and displayed lower plasma triiodothyronine levels. Skeletal muscles of transgenic mice were redder than wild-type animals suggesting an increased oxidative metabolism. In line with this observation, in gastrocnemius, we recorded a strong increase in cytochrome oxidase activity and in mitochondrial respiration. Moreover, we observed that p43 drives the formation of oxidative fibers: in soleus muscle, where MyHC IIa fibers were partly replaced by type I fibers; in gastrocnemius muscle, we found an increase in MyHC IIa and IIx expression associated with a reduction in the number of glycolytic fibers type IIb. In addition, we found that PGC-1α and PPARδ, two major regulators of muscle phenotype were up regulated in p43 transgenic mice suggesting that these proteins could be downstream targets of mitochondrial activity. These data indicate that the direct mitochondrial T3 pathway is deeply involved in the acquisition of contractile and metabolic features of muscle fibers in particular by regulating PGC-1α and PPARδ. PMID:18575627

SIRT1 Activation by Resveratrol Alleviates Cardiac Dysfunction via Mitochondrial Regulation in Diabetic Cardiomyopathy Mice

PubMed Central

Zhang, Ran; Chen, Jiangwei; Li, Xiang; Yang, Bo; Li, Xiujuan; Fan, Miaomiao; Li, Congye; Tian, Zuhong

2017-01-01

Background Diabetic cardiomyopathy (DCM) is a major threat for diabetic patients. Silent information regulator 1 (SIRT1) has a regulatory effect on mitochondrial dynamics, which is associated with DCM pathological changes. Our study aims to investigate whether resveratrol, a SRIT1 activator, could exert a protective effect against DCM. Methods and Results Cardiac-specific SIRT1 knockout (SIRT1KO) mice were generated using Cre-loxP system. SIRT1KO mice displayed symptoms of DCM, including cardiac hypertrophy and dysfunction, insulin resistance, and abnormal glucose metabolism. DCM and SIRT1KO hearts showed impaired mitochondrial biogenesis and function, while SIRT1 activation by resveratrol reversed this in DCM mice. High glucose caused increased apoptosis, impaired mitochondrial biogenesis, and function in cardiomyocytes, which was alleviated by resveratrol. SIRT1 deletion by both SIRT1KO and shRNA abolished the beneficial effects of resveratrol. Furthermore, the function of SIRT1 is mediated via the deacetylation effect on peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), thus inducing increased expression of nuclear respiratory factor 1 (NRF-1), NRF-2, estrogen-related receptor-α (ERR-α), and mitochondrial transcription factor A (TFAM). Conclusions Cardiac deletion of SIRT1 caused phenotypes resembling DCM. Activation of SIRT1 by resveratrol ameliorated cardiac injuries in DCM through PGC-1α-mediated mitochondrial regulation. Collectively, SIRT1 may serve as a potential therapeutic target for DCM. PMID:28883902

Mitochondrial Toxicity of Cadmium Telluride Quantum Dot Nanoparticles in Mammalian Hepatocytes

PubMed Central

Nguyen, Kathy C.; Rippstein, Peter; Tayabali, Azam F.; Willmore, William G.

2015-01-01

There are an increasing number of studies indicating that mitochondria are relevant targets in nanomaterial-induced toxicity. However, the underlying mechanisms by which nanoparticles (NPs) interact with these organelles and affect their functions are unknown. The aim of this study was to investigate the effects of cadmium telluride quantum dot (CdTe-QD) NPs on mitochondria in human hepatocellular carcinoma HepG2 cells. CdTe-QD treatment resulted in the enlargement of mitochondria as examined with transmission electron microscopy and confocal microscopy. CdTe-QDs appeared to associate with the isolated mitochondria as detected by their inherent fluorescence. Further analyses revealed that CdTe-QD caused disruption of mitochondrial membrane potential, increased intracellular calcium levels, impaired cellular respiration, and decreased adenosine triphosphate synthesis. The effects of CdTe-QDs on mitochondrial oxidative phosphorylation were evidenced by changes in levels and activities of the enzymes of the electron transport chain. Elevation of peroxisome proliferator-activated receptor-γ coactivator levels after CdTe-QD treatment suggested the effects of CdTe-QDs on mitochondrial biogenesis. Our results also showed that the effects of CdTe-QDs were similar or greater to those of cadmium chloride at equivalent concentrations of cadmium, suggesting that the toxic effects of CdTe-QDs were not solely due to cadmium released from the NPs. Overall, the study demonstrated that CdTe-QDs induced multifarious toxicity by causing changes in mitochondrial morphology and structure, as well as impairing their function and stimulating their biogenesis. PMID:25809595

Development of pharmacological strategies for mitochondrial disorders

PubMed Central

Kanabus, M; Heales, S J; Rahman, S

2014-01-01

Mitochondrial diseases are an unusually genetically and phenotypically heterogeneous group of disorders, which are extremely challenging to treat. Currently, apart from supportive therapy, there are no effective treatments for the vast majority of mitochondrial diseases. Huge scientific effort, however, is being put into understanding the mechanisms underlying mitochondrial disease pathology and developing potential treatments. To date, a variety of treatments have been evaluated by randomized clinical trials, but unfortunately, none of these has delivered breakthrough results. Increased understanding of mitochondrial pathways and the development of many animal models, some of which are accurate phenocopies of human diseases, are facilitating the discovery and evaluation of novel prospective treatments. Targeting reactive oxygen species has been a treatment of interest for many years; however, only in recent years has it been possible to direct antioxidant delivery specifically into the mitochondria. Increasing mitochondrial biogenesis, whether by pharmacological approaches, dietary manipulation or exercise therapy, is also currently an active area of research. Modulating mitochondrial dynamics and mitophagy and the mitochondrial membrane lipid milieu have also emerged as possible treatment strategies. Recent technological advances in gene therapy, including allotopic and transkingdom gene expression and mitochondrially targeted transcription activator-like nucleases, have led to promising results in cell and animal models of mitochondrial diseases, but most of these techniques are still far from clinical application. 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:24116962

Defects of mtDNA Replication Impaired Mitochondrial Biogenesis During Trypanosoma cruzi Infection in Human Cardiomyocytes and Chagasic Patients: The Role of Nrf1/2 and Antioxidant Response

PubMed Central

Wan, Xianxiu; Gupta, Shivali; Zago, Maria P.; Davidson, Mercy M.; Dousset, Pierre; Amoroso, Alejandro; Garg, Nisha Jain

2012-01-01

Background Mitochondrial dysfunction is a key determinant in chagasic cardiomyopathy development in mice; however, its relevance in human Chagas disease is not known. We determined if defects in mitochondrial biogenesis and dysregulation of peroxisome proliferator-activated receptor gamma (PPARγ) coactivator-1 (PGC-1)–regulated transcriptional pathways constitute a mechanism or mechanisms underlying mitochondrial oxidative-phosphorylation (OXPHOS) deficiency in human Chagas disease. Methods and Results We utilized human cardiomyocytes and left-ventricular tissue from chagasic and other cardiomyopathy patients and healthy donors (n>6/group). We noted no change in citrate synthase activity, yet mRNA and/or protein levels of subunits of the respiratory complexes were significantly decreased in Trypanosoma cruzi–infected cardiomyocytes (0 to 24 hours) and chagasic hearts. We observed increased mRNA and decreased nuclear localization of PGC-1-coactivated transcription factors, yet the expression of genes for PPARγ-regulated fatty acid oxidation and nuclear respiratory factor (NRF1/2)–regulated mtDNA replication and transcription machinery was enhanced in infected cardiomyocytes and chagasic hearts. The D-loop formation was normal or higher, but mtDNA replication and mtDNA content were decreased by 83% and 40% to 65%, respectively. Subsequently, we noted that reactive oxygen species (ROS), oxidative stress, and mtDNA oxidation were significantly increased, yet NRF1/2-regulated antioxidant gene expression remained compromised in infected cardiomyocytes and chagasic hearts. Conclusions The replication of mtDNA was severely compromised, resulting in a significant loss of mtDNA and expression of OXPHOS genes in T cruzi–infected cardiomyocytes and chagasic hearts. Our data suggest increased ROS generation and selective functional incapacity of NRF2-mediated antioxidant gene expression played a role in the defects in mtDNA replication and unfitness of mtDNA for

Isoliquiritigenin reduces oxidative damage and alleviates mitochondrial impairment by SIRT1 activation in experimental diabetic neuropathy.

PubMed

Yerra, Veera Ganesh; Kalvala, Anil Kumar; Kumar, Ashutosh

2017-09-01

Sirtuin (SIRT1) inactivation underlies the pathogenesis of insulin resistance and hyperglycaemia-associated vascular complications, but its role in diabetic neuropathy (DN) has not been yet explored. We have evaluated hyperglycaemia-induced alteration of SIRT1 signalling and the effect of isoliquiritigenin (ILQ) on SIRT1-directed AMP kinase (AMPK) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) signalling in peripheral nerves of streptozotocin (STZ) (55 mg/kg, ip)-induced diabetic rats and in high glucose (30 mM)-exposed neuro2a (N2A) cells. Diabetic rats and high glucose-exposed N2A cells showed reduction in SIRT1 expression with consequent decline in mitochondrial biogenesis and autophagy. ILQ (10 & 20 mg/kg, po) administration to diabetic rats for 2 weeks and exposure to glucose-insulted N2A cells resulted in significant SIRT1 activation with concurrent increase in mitochondrial biogenesis and autophagy. ILQ administration also enhanced NAD + /NADH ratio in peripheral sciatic nerves which explains its possible SIRT1 modulatory effect. Functional and behavioural studies show beneficial effect of ILQ as it alleviated nerve conduction and nerve blood flow deficits in diabetic rats along with improvement in behavioural parameters (hyperalgesia and allodynia). ILQ treatment to N2A cells reduced high glucose-driven ROS production and mitochondrial membrane depolarization. Further, ILQ-mediated SIRT1 activation facilitated the Nrf2-directed antioxidant signalling. Overall, results from this study suggest that SIRT1 activation by ILQ mimic effects of calorie restriction, that is, PGC-1α-mediated mitochondrial biogenesis, FOXO3a mediated stress resistance and AMPK mediated autophagy effects to counteract the multiple manifestations in experimental DN. Copyright © 2017 Elsevier Inc. All rights reserved.

The RNA-binding protein Hfq is important for ribosome biogenesis and affects translation fidelity.

PubMed

Andrade, José M; Dos Santos, Ricardo F; Chelysheva, Irina; Ignatova, Zoya; Arraiano, Cecília M

2018-06-01

Ribosome biogenesis is a complex process involving multiple factors. Here, we show that the widely conserved RNA chaperone Hfq, which can regulate sRNA-mRNA basepairing, plays a critical role in rRNA processing and ribosome assembly in Escherichia coli Hfq binds the 17S rRNA precursor and facilitates its correct processing and folding to mature 16S rRNA Hfq assists ribosome assembly and associates with pre-30S particles but not with mature 30S subunits. Inactivation of Hfq strikingly decreases the pool of mature 70S ribosomes. The reduction in ribosome levels depends on residues located in the distal face of Hfq but not on residues found in the proximal and rim surfaces which govern interactions with the sRNAs. Our results indicate that Hfq-mediated regulation of ribosomes is independent of its function as sRNA-regulator. Furthermore, we observed that inactivation of Hfq compromises translation efficiency and fidelity, both features of aberrantly assembled ribosomes. Our work expands the functions of the Sm-like protein Hfq beyond its function in small RNA-mediated regulation and unveils a novel role of Hfq as crucial in ribosome biogenesis and translation. © 2018 The Authors.

Maintenance of mitochondrial DNA copy number and expression are essential for preservation of mitochondrial function and cell growth.

PubMed

Jeng, Jaan-Yeh; Yeh, Tien-Shun; Lee, Jing-Wen; Lin, Shyh-Hsiang; Fong, Tsorng-Han; Hsieh, Rong-Hong

2008-02-01

To examine whether a reduction in the mtDNA level will compromise mitochondrial biogenesis and mitochondrial function, we created a cell model with depleted mtDNA. Stable transfection of small interfering (si)RNA of mitochondrial transcription factor A (Tfam) was used to interfere with Tfam gene expression. Selected stable clones showed 60-95% reduction in Tfam gene expression and 50-90% reduction in cytochrome b (Cyt b) gene expression. Tfam gene knockdown clones also showed decreased mtDNA-encoded cytochrome c oxidase subunit I (COX I) protein expression. However, no significant differences in protein expression were observed in nuclear DNA (nDNA)-encoded mitochondrial respiratory enzyme subunits. The cell morphology changed from a rhombus-like to a spindle-like form as determined in clones with decreased expressions of Tfam, mtRNA, and mitochondrial proteins. The mitochondrial respiratory enzyme activities and ATP production in such clones were significantly lower. The proportions of mtDNA mutations including 8-hydroxy-2'-deoxyguanosine (8-OHdG), a 4,977-bp deletion, and a 3,243-point mutation were also examined in these clones. No obvious increase in mtDNA mutations was observed in mitochondrial dysfunctional cell clones. The mitochondrial respiratory activity and ATP production ability recovered in cells with increased mtDNA levels after removal of the specific siRNA treatment. These experimental results provide direct evidence to substantiate that downregulation of mtDNA copy number and expression may compromise mitochondrial function and subsequent cell growth and morphology. (c) 2007 Wiley-Liss, Inc.

Sonic hedgehog pathway activation increases mitochondrial abundance and activity in hippocampal neurons

PubMed Central

Yao, Pamela J.; Manor, Uri; Petralia, Ronald S.; Brose, Rebecca D.; Wu, Ryan T. Y.; Ott, Carolyn; Wang, Ya-Xian; Charnoff, Ari; Lippincott-Schwartz, Jennifer; Mattson, Mark P.

2017-01-01

Mitochondria are essential organelles whose biogenesis, structure, and function are regulated by many signaling pathways. We present evidence that, in hippocampal neurons, activation of the Sonic hedgehog (Shh) signaling pathway affects multiple aspects of mitochondria. Mitochondrial mass was increased significantly in neurons treated with Shh. Using biochemical and fluorescence imaging analyses, we show that Shh signaling activity reduces mitochondrial fission and promotes mitochondrial elongation, at least in part, via suppression of the mitochondrial fission protein dynamin-like GTPase Drp1. Mitochondria from Shh-treated neurons were more electron-dense, as revealed by electron microscopy, and had higher membrane potential and respiratory activity. We further show that Shh protects neurons against a variety of stresses, including the mitochondrial poison rotenone, amyloid β-peptide, hydrogen peroxide, and high levels of glutamate. Collectively our data suggest a link between Shh pathway activity and the physiological properties of mitochondria in hippocampal neurons. PMID:27932496

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development.

PubMed

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa; Babu, Satish; Pal, Amit; Khare, Drirh; Godbole, Madan M

2010-07-02

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1alpha, NRF-1alpha and Tfam. Also, we for the first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development. Copyright 2010 Elsevier Inc. All rights reserved.

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development

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

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1{alpha}, NRF-1{alpha} and Tfam. Also, we for themore » first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development.« less

SIRT1/PGC-1α Signaling Promotes Mitochondrial Functional Recovery and Reduces Apoptosis after Intracerebral Hemorrhage in Rats

PubMed Central

Zhou, Yang; Wang, Shaohua; Li, Yixin; Yu, Shanshan; Zhao, Yong

2018-01-01

Silent information regulator 1 (SIRT1) exerts neuroprotection in many neurodegenerative diseases. However, it is not clear if SIRT1 has protective effects after intracerebral hemorrhage (ICH)-induced brain injury in rats. Thus, our goal was to examine the influence of SIRT1 on ICH injuries and any underlying mechanisms of this influence. Brain injury was induced by autologous arterial blood (60 μL) injection into rat brains, and data show that activation of SIRT1 with SRT1720 (5 mg/kg) restored nuclear SIRT1, deacetylation of PGC-1α, and mitochondrial biogenesis and decreased mortality, behavioral deficits, and brain water content without significant changes in phosphorylated AMP-activated protein kinase (pAMPK) induced by ICH. Activation of SIRT1 with SRT1720 also restored mitochondrial electron transport chain proteins and decreased apoptotic proteins in ICH; however, these changes were reversed after ICH. In contrast, treatment with PGC-1α siRNA yielded opposite effects. To explore the protective effects of SIRT1 after ICH, siRNAs were used to knockdown SIRT1. Treatment with SIRT1 siRNA increased mortality, behavioral deficits, brain water content, mitochondrial dysfunction, and neurocyte apoptosis after ICH. Thus, activation of SIRT1 promotes recovery of mitochondrial protein and function by increasing mitochondrial biogenesis and reduces apoptosis after ICH via the PGC-1α mitochondrial pathway. These data may suggest a new therapeutic approach for ICH injuries. PMID:29375306

Mitochondrial-Associated Cell Death Mechanisms Are Reset to an Embryonic-Like State in Aged Donor-Derived iPS Cells Harboring Chromosomal Aberrations

PubMed Central

Prigione, Alessandro; Hossini, Amir M.; Lichtner, Björn; Serin, Akdes; Fauler, Beatrix; Megges, Matthias; Lurz, Rudi; Lehrach, Hans; Zouboulis, Christos C.

2011-01-01

Somatic cells reprogrammed into induced pluripotent stem cells (iPSCs) acquire features of human embryonic stem cells (hESCs) and thus represent a promising source for cellular therapy of debilitating diseases, such as age-related disorders. However, reprogrammed cell lines have been found to harbor various genomic alterations. In addition, we recently discovered that the mitochondrial DNA of human fibroblasts also undergoes random mutational events upon reprogramming. Aged somatic cells might possess high susceptibility to nuclear and mitochondrial genome instability. Hence, concerns over the oncogenic potential of reprogrammed cells due to the lack of genomic integrity may hinder the applicability of iPSC-based therapies for age-associated conditions. Here, we investigated whether aged reprogrammed cells harboring chromosomal abnormalities show resistance to apoptotic cell death or mitochondrial-associated oxidative stress, both hallmarks of cancer transformation. Four iPSC lines were generated from dermal fibroblasts derived from an 84-year-old woman, representing the oldest human donor so far reprogrammed to pluripotency. Despite the presence of karyotype aberrations, all aged-iPSCs were able to differentiate into neurons, re-establish telomerase activity, and reconfigure mitochondrial ultra-structure and functionality to a hESC-like state. Importantly, aged-iPSCs exhibited high sensitivity to drug-induced apoptosis and low levels of oxidative stress and DNA damage, in a similar fashion as iPSCs derived from young donors and hESCs. Thus, the occurrence of chromosomal abnormalities within aged reprogrammed cells might not be sufficient to over-ride the cellular surveillance machinery and induce malignant transformation through the alteration of mitochondrial-associated cell death. Taken together, we unveiled that cellular reprogramming is capable of reversing aging-related features in somatic cells from a very old subject, despite the presence of genomic

Exercise training improves vascular mitochondrial function

PubMed Central

Park, Song-Young; Rossman, Matthew J.; Gifford, Jayson R.; Bharath, Leena P.; Bauersachs, Johann; Richardson, Russell S.; Abel, E. Dale; Symons, J. David

2016-01-01

Exercise training is recognized to improve cardiac and skeletal muscle mitochondrial respiratory capacity; however, the impact of chronic exercise on vascular mitochondrial respiratory function is unknown. We hypothesized that exercise training concomitantly increases both vascular mitochondrial respiratory capacity and vascular function. Arteries from both sedentary (SED) and swim-trained (EX, 5 wk) mice were compared in terms of mitochondrial respiratory function, mitochondrial content, markers of mitochondrial biogenesis, redox balance, nitric oxide (NO) signaling, and vessel function. Mitochondrial complex I and complex I + II state 3 respiration and the respiratory control ratio (complex I + II state 3 respiration/complex I state 2 respiration) were greater in vessels from EX relative to SED mice, despite similar levels of arterial citrate synthase activity and mitochondrial DNA content. Furthermore, compared with the SED mice, arteries from EX mice displayed elevated transcript levels of peroxisome proliferative activated receptor-γ coactivator-1α and the downstream targets cytochrome c oxidase subunit IV isoform 1, isocitrate dehydrogenase (Idh) 2, and Idh3a, increased manganese superoxide dismutase protein expression, increased endothelial NO synthase phosphorylation (Ser1177), and suppressed reactive oxygen species generation (all P < 0.05). Although there were no differences in EX and SED mice concerning endothelium-dependent and endothelium-independent vasorelaxation, phenylephrine-induced vasocontraction was blunted in vessels from EX compared with SED mice, and this effect was normalized by NOS inhibition. These training-induced increases in vascular mitochondrial respiratory capacity and evidence of improved redox balance, which may, at least in part, be attributable to elevated NO bioavailability, have the potential to protect against age- and disease-related challenges to arterial function. PMID:26825520

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

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

Tan, Jun; Song, Meijun; Zhou, Mi

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

Mitochondrial loss, dysfunction and altered dynamics in Huntington's disease.

PubMed

Kim, Jinho; Moody, Jennifer P; Edgerly, Christina K; Bordiuk, Olivia L; Cormier, Kerry; Smith, Karen; Beal, M Flint; Ferrante, Robert J

2010-10-15

Although a direct causative pathway from the gene mutation to the selective neostriatal neurodegeneration remains unclear in Huntington's disease (HD), one putative pathological mechanism reported to play a prominent role in the pathogenesis of this neurological disorder is mitochondrial dysfunction. We examined mitochondria in preferentially vulnerable striatal calbindin-positive neurons in moderate-to-severe grade HD patients, using antisera against mitochondrial markers of COX2, SOD2 and cytochrome c. Combined calbindin and mitochondrial marker immunofluorescence showed a significant and progressive grade-dependent reduction in the number of mitochondria in spiny striatal neurons, with marked alteration in size. Consistent with mitochondrial loss, there was a reduction in COX2 protein levels using western analysis that corresponded with disease severity. In addition, both mitochondrial transcription factor A, a regulator of mtDNA, and peroxisome proliferator-activated receptor-co-activator gamma-1 alpha, a key transcriptional regulator of energy metabolism and mitochondrial biogenesis, were also significantly reduced with increasing disease severity. Abnormalities in mitochondrial dynamics were observed, showing a significant increase in the fission protein Drp1 and a reduction in the expression of the fusion protein mitofusin 1. Lastly, mitochondrial PCR array profiling in HD caudate nucleus specimens showed increased mRNA expression of proteins involved in mitochondrial localization, membrane translocation and polarization and transport that paralleled mitochondrial derangement. These findings reveal that there are both mitochondrial loss and altered mitochondrial morphogenesis with increased mitochondrial fission and reduced fusion in HD. These findings provide further evidence that mitochondrial dysfunction plays a critical role in the pathogenesis of HD.

Cardiac-Targeted Transgenic Mutant Mitochondrial Enzymes

PubMed Central

Kohler, James J.; Hosseini, Seyed H.; Green, Elgin; Hoying-Brandt, Amy; Cucoranu, Ioan; Haase, Chad P.; Russ, Rodney; Srivastava, Jaya; Ivey, Kristopher; Ludaway, Tomika; Kapoor, Victor; Abuin, Allison; Shapoval, Alexsey; Santoianni, Robert; Saada, Ann; Elpeleg, Orly; Lewis, William

2009-01-01

Mitochondrial (mt) DNA biogenesis is critical to cardiac contractility. DNA polymerase gamma (pol γ) replicates mtDNA, whereas thymidine kinase 2 (TK2) monophosphorylates pyrimidines intramitochondrially. Point mutations in POLG and TK2 result in clinical diseases associated with mtDNA depletion and organ dysfunction. Pyrimidine analogs (NRTIs) inhibit Pol γ and mtDNA replication. Cardiac “dominant negative” murine transgenes (TGs; Pol γ Y955G, and TK2 H121N or I212N) defined the role of each in the heart. mtDNA abundance, histopathological features, histochemistry, mitochondrial protein abundance, morphometry, and echocardiography were determined for TGs in “2 × 2” studies with or without pyrimidine analogs. Cardiac mtDNA abundance decreased in Y955C TGs (∼50%) but increased in H121N and I212N TGs (20-70%). Succinate dehydrogenase (SDH) increased in hearts of all mutants. Ultrastructural changes occurred in Y955C and H121N TGs. Histopathology demonstrated hypertrophy in H121N, LV dilation in I212N, and both hypertrophy and dilation in Y955C TGs. Antiretrovirals increased LV mass (≈50%) for all three TGs which combined with dilation indicates cardiomyopathy. Taken together, these studies demonstrate three manifestations of cardiac dysfunction that depend on the nature of the specific mutation and antiretroviral treatment. Mutations in genes for mtDNA biogenesis increase risk for defective mtDNA replication, leading to LV hypertrophy. PMID:18446447

Mitochondrial NAD(P)H In vivo: Identifying Natural Indicators of Oxidative Phosphorylation in the (31)P Magnetic Resonance Spectrum.

PubMed

Conley, Kevin E; Ali, Amir S; Flores, Brandon; Jubrias, Sharon A; Shankland, Eric G

2016-01-01

Natural indicators provide intrinsic probes of metabolism, biogenesis and oxidative protection. Nicotinamide adenine dinucleotide metabolites (NAD(P)) are one class of indicators that have roles as co-factors in oxidative phosphorylation, glycolysis, and anti-oxidant protection, as well as signaling in the mitochondrial biogenesis pathway. These many roles are made possible by the distinct redox states (NAD(P)(+) and NAD(P)H), which are compartmentalized between cytosol and mitochondria. Here we provide evidence for detection of NAD(P)(+) and NAD(P)H in separate mitochondrial and cytosol pools in vivo in human tissue by phosphorus magnetic resonance spectroscopy ((31)P MRS). These NAD(P) pools are identified by chemical standards (NAD(+), NADP(+), and NADH) and by physiological tests. A unique resonance reflecting mitochondrial NAD(P)H is revealed by the changes elicited by elevation of mitochondrial oxidation. The decline of NAD(P)H with oxidation is matched by a stoichiometric rise in the NAD(P)(+) peak. This unique resonance also provides a measure of the improvement in mitochondrial oxidation that parallels the greater phosphorylation found after exercise training in these elderly subjects. The implication is that the dynamics of the mitochondrial NAD(P)H peak provides an intrinsic probe of the reversal of mitochondrial dysfunction in elderly muscle. Thus, non-invasive detection of NAD(P)(+) and NAD(P)H in cytosol vs. mitochondria yields natural indicators of redox compartmentalization and sensitive intrinsic probes of the improvement of mitochondrial function with an intervention in human tissues in vivo. These natural indicators hold the promise of providing mechanistic insight into metabolism and mitochondrial function in vivo in a range of tissues in health, disease and with treatment.

Gemfibrozil pretreatment resulted in a sexually dimorphic outcome in the rat models of global cerebral ischemia-reperfusion via modulation of mitochondrial pro-survival and apoptotic cell death factors as well as MAPKs.

PubMed

Mohagheghi, Fatemeh; Ahmadiani, Abolhassan; Rahmani, Behrouz; Moradi, Fatemeh; Romond, Nathalie; Khalaj, Leila

2013-07-01

Inducers of mitochondrial biogenesis are widely under investigation for use in a novel therapeutic approach in neurodegenerative disorders. The ability of Gemfibrozil, a fibrate, is investigated for the first time to modulate mitochondrial pro-survival factors involved in the mitochondrial biogenesis signaling pathway, including peroxisome proliferator-activated receptor coactivator-1α (PGC-1α), nuclear respiratory factor (NRF-1), and mitochondrial transcription factor A (TFAM) in the brain. Gemfibozil is clinically administered to control hyperlipidemia. It secondarily prevents cardiovascular events such as cardiac arrest in susceptible patients. In this study, pretreatment of animals with gemfibrozil prior to ischemia-reperfusion (I/R) resulted in a sexually dimorphic outcome. While the expression of NRF-1 and TFAM were induced in gemfibrozil-pretreated met-estrous females, they were suppressed in males. Gemfibrozil also proved to be neuroprotective in met-estrous females, as it inhibited caspase-dependent apoptosis while in males it led to hippocampal neurodegeneration via activation of both the caspase-dependent and caspase-independent apoptosis. In the mitogen-activated protein kinase (MAPKs) pathway, gemfibrozil pretreatment induced the expression of extracellular signal-regulated kinases (ERK1/2) in met-estrous females and reduced it in males. These findings correlatively point to the sexual-dimorphic effects of gemfibrozil in global cerebral I/R context by affecting important factors involved in the mitochondrial biogenesis, MAPKs, and apoptotic cell death pathways.

Skeletal muscle mitochondrial energetics in obesity and type 2 diabetes mellitus: endocrine aspects.

PubMed

Aguer, Céline; Harper, Mary-Ellen

2012-12-01

During the development of type 2 diabetes mellitus, skeletal muscle is a major site of insulin resistance. The latter has been linked to mitochondrial dysfunction and impaired fatty acid oxidation. Some hormones like insulin, thyroid hormones and adipokines (e.g., leptin, adiponectin) have positive effects on muscle mitochondrial bioenergetics through their direct or indirect effects on mitochondrial biogenesis, mitochondrial protein expression, mitochondrial enzyme activities and/or AMPK pathway activation--all of which can improve fatty acid oxidation. It is therefore not surprising that treatment with these hormones has been proposed to improve muscle and whole body insulin sensitivity. However, treatment of diabetic patients with leptin and adiponectin has no effect on muscle mitochondrial bioenergetics showing resistance to these hormones during type 2 diabetes. Furthermore, treatment with most thyroid hormones has unexpectedly revealed negative effects on muscle insulin sensitivity. Future research should focus on development of agents that improve metabolic dysfunction downstream of hormone receptors. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Mitochondrial and microcirculatory distress syndrome in the critical patient. Therapeutic implications].

PubMed

Navarrete, M L; Cerdeño, M C; Serra, M C; Conejero, R

2013-10-01

Mitochondrial and microcirculatory distress syndrome (MMDS) can occur during systemic inflammatory response syndrome (SIRS), and is characterized by cytopathic tissue hypoxia uncorrected by oxygen transport optimization, and associated with an acquired defect in the use of oxygen and energy production in mitochondria, leading to multiple organ dysfunction (MOD). We examine the pathogenesis of MMDS, new diagnostic methods, and recent therapeutic approaches adapted to each of the three phases in the evolution of the syndrome. In the initial phase, the aim is prevention and early reversal of mitochondrial dysfunction. Once the latter is established, the aim is to restore flow of the electron chain, mitochondrial respiration, and to avoid cellular energy collapse. Finally, in the third (resolution) stage, treatment should focus on stimulating mitochondrial biogenesis and the repair or replacement of damaged mitochondria. Copyright © 2012 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Mitochondrial AAA proteases--towards a molecular understanding of membrane-bound proteolytic machines.

PubMed

Gerdes, Florian; Tatsuta, Takashi; Langer, Thomas

2012-01-01

Mitochondrial AAA proteases play an important role in the maintenance of mitochondrial proteostasis. They regulate and promote biogenesis of mitochondrial proteins by acting as processing enzymes and ensuring the selective turnover of misfolded proteins. Impairment of AAA proteases causes pleiotropic defects in various organisms including neurodegeneration in humans. AAA proteases comprise ring-like hexameric complexes in the mitochondrial inner membrane and are functionally conserved from yeast to man, but variations are evident in the subunit composition of orthologous enzymes. Recent structural and biochemical studies revealed how AAA proteases degrade their substrates in an ATP dependent manner. Intersubunit coordination of the ATP hydrolysis leads to an ordered ATP hydrolysis within the AAA ring, which ensures efficient substrate dislocation from the membrane and translocation to the proteolytic chamber. In this review, we summarize recent findings on the molecular mechanisms underlying the versatile functions of mitochondrial AAA proteases and their relevance to those of the other AAA+ machines. Copyright © 2011 Elsevier B.V. All rights reserved.

Mitochondrial plasticity in cancer-related muscle wasting: potential approaches for its management.

PubMed

Vitorino, Rui; Moreira-Gonçalves, Daniel; Ferreira, Rita

2015-05-01

Cancer cachexia represents a critical problem in clinical oncology due to its negative impact on patients' quality of life, therapeutic tolerance and survival. This paraneoplasic condition is characterized by significant weight loss mainly from skeletal muscle wasting. Understanding the molecular mechanisms underlying cancer cachexia is urgent in order to develop and apply efficient therapeutic strategies. Mitochondrial dysfunction is an early event in cancer-induced muscle wasting. Decreased ability for ATP synthesis, impaired mitochondrial biogenesis, increased oxidative stress, impairment of protein quality control systems, increased susceptibility to mitophagy and to apoptosis were all shown to mediate contractile dysfunction and wasting in cancer cachexia. Anti-inflammatory therapies as well as exercise training seem to counteract muscle mass loss in part by improving mitochondrial functionality. Given its central role in muscle wasting, mitochondrial plasticity should be viewed as a key therapeutic target for the preservation of muscle mass in cancer cachexia. Few studies have addressed the mitochondrial events modulated by cancer cachexia and contradictory data were reported. Scarcer studies have focused on the mitochondrial adaptation to anticancer cachexia strategies.

An essential function of the mitochondrial sulfhydryl oxidase Erv1p/ALR in the maturation of cytosolic Fe/S proteins

PubMed Central

Lange, Heike; Lisowsky, Thomas; Gerber, Jana; Mühlenhoff, Ulrich; Kispal, Gyula; Lill, Roland

2001-01-01

Biogenesis of Fe/S clusters involves a number of essential mitochondrial proteins. Here, we identify the essential Erv1p of Saccharomyces cerevisia mitochondria as a novel component that is specifically required for the maturation of Fe/S proteins in the cytosol, but not in mitochondria. Furthermore, Erv1p was found to be important for cellular iron homeostasis. The homologous mammalian protein ALR (‘augmenter of liver regeneration’), also termed hepatopoietin, can functionally replace defects in Erv1p and thus represents the mammalian orthologue of yeast Erv1p. Previously, a fragment of ALR was reported to exhibit an activity as an extracellular hepatotrophic growth factor. Both Erv1p and full-length ALR are located in the mitochondrial intermembrane space and represent the first components of this compartment with a role in the biogenesis of cytosolic Fe/S proteins. It is likely that Erv1p/ALR operates downstream of the mitochondrial ABC transporter Atm1p/ABC7/Sta1, which also executes a specific task in this essential biochemical process. PMID:11493598

An essential function of the mitochondrial sulfhydryl oxidase Erv1p/ALR in the maturation of cytosolic Fe/S proteins.

PubMed

Lange, H; Lisowsky, T; Gerber, J; Mühlenhoff, U; Kispal, G; Lill, R

2001-08-01

Biogenesis of Fe/S clusters involves a number of essential mitochondrial proteins. Here, we identify the essential Erv1p of Saccharomyces cerevisia mitochondria as a novel component that is specifically required for the maturation of Fe/S proteins in the cytosol, but not in mitochondria. Furthermore, Erv1p was found to be important for cellular iron homeostasis. The homologous mammalian protein ALR ('augmenter of liver regeneration'), also termed hepatopoietin, can functionally replace defects in Erv1p and thus represents the mammalian orthologue of yeast Erv1p. Previously, a fragment of ALR was reported to exhibit an activity as an extracellular hepatotrophic growth factor. Both Erv1p and full-length ALR are located in the mitochondrial intermembrane space and represent the first components of this compartment with a role in the biogenesis of cytosolic Fe/S proteins. It is likely that Erv1p/ALR operates downstream of the mitochondrial ABC transporter Atm1p/ABC7/Sta1, which also executes a specific task in this essential biochemical process.

Laminar shear stress promotes mitochondrial homeostasis in endothelial cells.

PubMed

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

2018-06-01

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

Heme oxygenase-1 regulates mitochondrial quality control in the heart

PubMed Central

Hull, Travis D.; Boddu, Ravindra; Guo, Lingling; Tisher, Cornelia C.; Traylor, Amie M.; Patel, Bindiya; Joseph, Reny; Prabhu, Sumanth D.; Suliman, Hagir B.; Piantadosi, Claude A.; George, James F.

2016-01-01

The cardioprotective inducible enzyme heme oxygenase-1 (HO-1) degrades prooxidant heme into equimolar quantities of carbon monoxide, biliverdin, and iron. We hypothesized that HO-1 mediates cardiac protection, at least in part, by regulating mitochondrial quality control. We treated WT and HO-1 transgenic mice with the known mitochondrial toxin, doxorubicin (DOX). Relative to WT mice, mice globally overexpressing human HO-1 were protected from DOX-induced dilated cardiomyopathy, cardiac cytoarchitectural derangement, and infiltration of CD11b+ mononuclear phagocytes. Cardiac-specific overexpression of HO-1 ameliorated DOX-mediated dilation of the sarcoplasmic reticulum as well as mitochondrial disorganization in the form of mitochondrial fragmentation and increased numbers of damaged mitochondria in autophagic vacuoles. HO-1 overexpression promotes mitochondrial biogenesis by upregulating protein expression of NRF1, PGC1α, and TFAM, which was inhibited in WT animals treated with DOX. Concomitantly, HO-1 overexpression inhibited the upregulation of the mitochondrial fission mediator Fis1 and resulted in increased expression of the fusion mediators, Mfn1 and Mfn2. It also prevented dynamic changes in the levels of key mediators of the mitophagy pathway, PINK1 and parkin. Therefore, these findings suggest that HO-1 has a novel role in protecting the heart from oxidative injury by regulating mitochondrial quality control. PMID:27110594

Insulin alleviates mitochondrial oxidative stress involving upregulation of superoxide dismutase 2 and uncoupling protein 2 in septic acute kidney injury

PubMed Central

Chen, Guang-Dao; Zhang, Jun-Liang; Chen, Yi-Ting; Zhang, Ju-Xing; Wang, Tao; Zeng, Qi-Yi

2018-01-01

The aim of the present study was to explore the effects and mechanisms of insulin on mitochondrial oxidative stress in septic acute kidney injury (AKI). Male Sprague Dawley rats were divided randomly into four groups: Control group, sham surgery group, cecal ligation and puncture (CLP) group, and CLP plus insulin group. Blood specimens and kidney tissues were obtained at 12 and 24 h after surgery as separate experiments. Analyses of histology and indicators of renal injury [blood urea nitrogen (BUN) and serum creatinine (CRE) and neutrophil gelatinase-associated lipocalin (NGAL)], mitochondrial function [adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP)], oxidative stress [inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS) and nitric oxide (NO)], endogenous antioxidant systems [superoxide dismutase (SOD) and glutathione (GSH)] as well as the expression of uncoupling protein (UCP), PINK1 protein (a major mediator of mitophagy), PGC1α protein (a major regulator of mitochondrial biogenesis) were performed. Compared with CLP group, the CLP plus insulin group had milder histological damage, higher levels of ATP and MMP as well as lower levels of BUN, serum CRE and NGAL, intrarenal iNOS, mitochondrial ROS and total NO. Moreover, the CLP plus insulin group demonstrated increased expression of SOD2 and UCP2. In contrast, insulin administration suppressed mitophagy meanwhile did not upregulate total GSH and induce mitochondrial biogenesis following CLP. These findings indicated that the upregulation of SOD2 and UCP2 may be involved in insulin protecting against mitochondrial oxidative stress in septic AKI. PMID:29563990

Insulin alleviates mitochondrial oxidative stress involving upregulation of superoxide dismutase 2 and uncoupling protein 2 in septic acute kidney injury.

PubMed

Chen, Guang-Dao; Zhang, Jun-Liang; Chen, Yi-Ting; Zhang, Ju-Xing; Wang, Tao; Zeng, Qi-Yi

2018-04-01

The aim of the present study was to explore the effects and mechanisms of insulin on mitochondrial oxidative stress in septic acute kidney injury (AKI). Male Sprague Dawley rats were divided randomly into four groups: Control group, sham surgery group, cecal ligation and puncture (CLP) group, and CLP plus insulin group. Blood specimens and kidney tissues were obtained at 12 and 24 h after surgery as separate experiments. Analyses of histology and indicators of renal injury [blood urea nitrogen (BUN) and serum creatinine (CRE) and neutrophil gelatinase-associated lipocalin (NGAL)], mitochondrial function [adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP)], oxidative stress [inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS) and nitric oxide (NO)], endogenous antioxidant systems [superoxide dismutase (SOD) and glutathione (GSH)] as well as the expression of uncoupling protein (UCP), PINK1 protein (a major mediator of mitophagy), PGC1α protein (a major regulator of mitochondrial biogenesis) were performed. Compared with CLP group, the CLP plus insulin group had milder histological damage, higher levels of ATP and MMP as well as lower levels of BUN, serum CRE and NGAL, intrarenal iNOS, mitochondrial ROS and total NO. Moreover, the CLP plus insulin group demonstrated increased expression of SOD2 and UCP2. In contrast, insulin administration suppressed mitophagy meanwhile did not upregulate total GSH and induce mitochondrial biogenesis following CLP. These findings indicated that the upregulation of SOD2 and UCP2 may be involved in insulin protecting against mitochondrial oxidative stress in septic AKI.

PINK1/Parkin-Dependent Mitochondrial Surveillance: From Pleiotropy to Parkinson's Disease

PubMed Central

Mouton-Liger, Francois; Jacoupy, Maxime; Corvol, Jean-Christophe; Corti, Olga

2017-01-01

Parkinson's disease (PD) is one of the most frequent neurodegenerative disease caused by the preferential, progressive degeneration of the dopaminergic (DA) neurons of the substantia nigra (SN) pars compacta. PD is characterized by a multifaceted pathological process involving protein misfolding, mitochondrial dysfunction, neuroinflammation and metabolism deregulation. The molecular mechanisms governing the complex interplay between the different facets of this process are still unknown. PARK2/Parkin and PARK6/PINK1, two genes responsible for familial forms of PD, act as a ubiquitous core signaling pathway, coupling mitochondrial stress to mitochondrial surveillance, by regulating mitochondrial dynamics, the removal of damaged mitochondrial components by mitochondria-derived vesicles, mitophagy, and mitochondrial biogenesis. Over the last decade, PINK1/Parkin-dependent mitochondrial quality control emerged as a pleiotropic regulatory pathway. Loss of its function impinges on a number of physiological processes suspected to contribute to PD pathogenesis. Its role in the regulation of innate immunity and inflammatory processes stands out, providing compelling support to the contribution of non-cell-autonomous immune mechanisms in PD. In this review, we illustrate the central role of this multifunctional pathway at the crossroads between mitochondrial stress, neuroinflammation and metabolism. We discuss how its dysfunction may contribute to PD pathogenesis and pinpoint major unresolved questions in the field. PMID:28507507

Hypoxia signaling controls postnatal changes in cardiac mitochondrial morphology and function

PubMed Central

Neary, Marianne T.; Ng, Keat-Eng; Ludtmann, Marthe H.R.; Hall, Andrew R.; Piotrowska, Izabela; Ong, Sang-Bing; Hausenloy, Derek J.; Mohun, Timothy J.; Abramov, Andrey Y.; Breckenridge, Ross A.

2014-01-01

Fetal cardiomyocyte adaptation to low levels of oxygen in utero is incompletely understood, and is of interest as hypoxia tolerance is lost after birth, leading to vulnerability of adult cardiomyocytes. It is known that cardiac mitochondrial morphology, number and function change significantly following birth, although the underlying molecular mechanisms and physiological stimuli are undefined. Here we show that the decrease in cardiomyocyte HIF-signaling in cardiomyocytes immediately after birth acts as a physiological switch driving mitochondrial fusion and increased postnatal mitochondrial biogenesis. We also investigated mechanisms of ATP generation in embryonic cardiac mitochondria. We found that embryonic cardiac cardiomyocytes rely on both glycolysis and the tricarboxylic acid cycle to generate ATP, and that the balance between these two metabolic pathways in the heart is controlled around birth by the reduction in HIF signaling. We therefore propose that the increase in ambient oxygen encountered by the neonate at birth acts as a key physiological stimulus to cardiac mitochondrial adaptation. PMID:24984146

COX16 promotes COX2 metallation and assembly during respiratory complex IV biogenesis

PubMed Central

Aich, Abhishek; Wang, Cong; Chowdhury, Arpita; Ronsör, Christin; Pacheu-Grau, David; Richter-Dennerlein, Ricarda; Dennerlein, Sven

2018-01-01

Cytochrome c oxidase of the mitochondrial oxidative phosphorylation system reduces molecular oxygen with redox equivalent-derived electrons. The conserved mitochondrial-encoded COX1- and COX2-subunits are the heme- and copper-center containing core subunits that catalyze water formation. COX1 and COX2 initially follow independent biogenesis pathways creating assembly modules with subunit-specific, chaperone-like assembly factors that assist in redox centers formation. Here, we find that COX16, a protein required for cytochrome c oxidase assembly, interacts specifically with newly synthesized COX2 and its copper center-forming metallochaperones SCO1, SCO2, and COA6. The recruitment of SCO1 to the COX2-module is COX16- dependent and patient-mimicking mutations in SCO1 affect interaction with COX16. These findings implicate COX16 in CuA-site formation. Surprisingly, COX16 is also found in COX1-containing assembly intermediates and COX2 recruitment to COX1. We conclude that COX16 participates in merging the COX1 and COX2 assembly lines. PMID:29381136

Dysfunction in the mitochondrial Fe-S assembly machinery leads to formation of the chemoresistant truncated VDAC1 isoform without HIF-1α activation

PubMed Central

Ferecatu, Ioana; Canal, Frédéric; Fabbri, Lucilla; Mazure, Nathalie M.; Bouton, Cécile

2018-01-01

Biogenesis of iron-sulfur clusters (ISC) is essential to almost all forms of life and involves complex protein machineries. This process is initiated within the mitochondrial matrix by the ISC assembly machinery. Cohort and case report studies have linked mutations in ISC assembly machinery to severe mitochondrial diseases. The voltage-dependent anion channel (VDAC) located within the mitochondrial outer membrane regulates both cell metabolism and apoptosis. Recently, the C-terminal truncation of the VDAC1 isoform, termed VDAC1-ΔC, has been observed in chemoresistant late-stage tumor cells grown under hypoxic conditions with activation of the hypoxia-response nuclear factor HIF-1α. These cells harbored atypical enlarged mitochondria. Here, we show for the first time that depletion of several proteins of the mitochondrial ISC machinery in normoxia leads to a similar enlarged mitochondria phenotype associated with accumulation of VDAC1-ΔC. This truncated form of VDAC1 accumulates in the absence of HIF-1α and HIF-2α activations and confers cell resistance to drug-induced apoptosis. Furthermore, we show that when hypoxia and siRNA knock-down of the ISC machinery core components are coupled, the cell phenotype is further accentuated, with greater accumulation of VDAC1-ΔC. Interestingly, we show that hypoxia promotes the downregulation of several proteins (ISCU, NFS1, FXN) involved in the early steps of mitochondrial Fe-S cluster biogenesis. Finally, we have identified the mitochondria-associated membrane (MAM) localized Fe-S protein CISD2 as a link between ISC machinery downregulation and accumulation of anti-apoptotic VDAC1-ΔC. Our results are the first to associate dysfunction in Fe-S cluster biogenesis with cleavage of VDAC1, a form which has previously been shown to promote tumor resistance to chemotherapy, and raise new perspectives for targets in cancer therapy. PMID:29596470

Skeletal muscle mitochondrial health and spinal cord injury.

PubMed

O'Brien, Laura C; Gorgey, Ashraf S

2016-10-18

Mitochondria are the main source of cellular energy production and are dynamic organelles that undergo biogenesis, remodeling, and degradation. Mitochondrial dysfunction is observed in a number of disease states including acute and chronic central or peripheral nervous system injury by traumatic brain injury, spinal cord injury (SCI), and neurodegenerative disease as well as in metabolic disturbances such as insulin resistance, type II diabetes and obesity. Mitochondrial dysfunction is most commonly observed in high energy requiring tissues like the brain and skeletal muscle. In persons with chronic SCI, changes to skeletal muscle may include remarkable atrophy and conversion of muscle fiber type from oxidative to fast glycolytic, combined with increased infiltration of intramuscular adipose tissue. These changes contribute to a proinflammatory environment, glucose intolerance and insulin resistance. The loss of metabolically active muscle combined with inactivity predisposes individuals with SCI to type II diabetes and obesity. The contribution of skeletal muscle mitochondrial density and electron transport chain activity to the development of the aforementioned comorbidities following SCI is unclear. A better understanding of the mechanisms involved in skeletal muscle mitochondrial dynamics is imperative to designing and testing effective treatments for this growing population. The current editorial will review ways to study mitochondrial function and the importance of improving skeletal muscle mitochondrial health in clinical populations with a special focus on chronic SCI.

Mitochondrial heat shock protein (Hsp) 70 and Hsp10 cooperate in the formation of Hsp60 complexes.

PubMed

Böttinger, Lena; Oeljeklaus, Silke; Guiard, Bernard; Rospert, Sabine; Warscheid, Bettina; Becker, Thomas

2015-05-01

Mitochondrial Hsp70 (mtHsp70) mediates essential functions for mitochondrial biogenesis, like import and folding of proteins. In these processes, the chaperone cooperates with cochaperones, the presequence translocase, and other chaperone systems. The chaperonin Hsp60, together with its cofactor Hsp10, catalyzes folding of a subset of mtHsp70 client proteins. Hsp60 forms heptameric ring structures that provide a cavity for protein folding. How the Hsp60 rings are assembled is poorly understood. In a comprehensive interaction study, we found that mtHsp70 associates with Hsp60 and Hsp10. Surprisingly, mtHsp70 interacts with Hsp10 independently of Hsp60. The mtHsp70-Hsp10 complex binds to the unassembled Hsp60 precursor to promote its assembly into mature Hsp60 complexes. We conclude that coupling to Hsp10 recruits mtHsp70 to mediate the biogenesis of the heptameric Hsp60 rings. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Effects of exercise on obesity-induced mitochondrial dysfunction in skeletal muscle

PubMed Central

Heo, Jun-Won; No, Mi-Hyun; Park, Dong-Ho; Kang, Ju-Hee; Seo, Dae Yun; Han, Jin; Neufer, P. Darrell

2017-01-01

Obesity is known to induce inhibition of glucose uptake, reduction of lipid metabolism, and progressive loss of skeletal muscle function, which are all associated with mitochondrial dysfunction in skeletal muscle. Mitochondria are dynamic organelles that regulate cellular metabolism and bioenergetics, including ATP production via oxidative phosphorylation. Due to these critical roles of mitochondria, mitochondrial dysfunction results in various diseases such as obesity and type 2 diabetes. Obesity is associated with impairment of mitochondrial function (e.g., decrease in O2 respiration and increase in oxidative stress) in skeletal muscle. The balance between mitochondrial fusion and fission is critical to maintain mitochondrial homeostasis in skeletal muscle. Obesity impairs mitochondrial dynamics, leading to an unbalance between fusion and fission by favorably shifting fission or reducing fusion proteins. Mitophagy is the catabolic process of damaged or unnecessary mitochondria. Obesity reduces mitochondrial biogenesis in skeletal muscle and increases accumulation of dysfunctional cellular organelles, suggesting that mitophagy does not work properly in obesity. Mitochondrial dysfunction and oxidative stress are reported to trigger apoptosis, and mitochondrial apoptosis is induced by obesity in skeletal muscle. It is well known that exercise is the most effective intervention to protect against obesity. Although the cellular and molecular mechanisms by which exercise protects against obesity-induced mitochondrial dysfunction in skeletal muscle are not clearly elucidated, exercise training attenuates mitochondrial dysfunction, allows mitochondria to maintain the balance between mitochondrial dynamics and mitophagy, and reduces apoptotic signaling in obese skeletal muscle. PMID:29200899

Increased mitochondrial-encoded gene transcription in immortal DF-1 cells.

PubMed

Kim, H; You, S; Kim, I J; Farris, J; Foster, L K; Foster, D N

2001-05-01

We have established, in continuous cell culture, a spontaneously immortalized chicken embryo fibroblast (CEF) cell line (DF-1) as well as several other immortal CEF cell lines. The immortal DF-1 cells divided more rapidly than primary and other immortal CEF cells. To identify the genes involved in rapidly dividing DF-1 cells, we have used differential display RT-PCR. Of the numerous genes analyzed, three mitochondrial-encoded genes (ATPase 8/6, 16S rRNA, and cytochrome b) were shown to express at higher levels in DF-1 cells compared to primary and other immortal CEF cells. The inhibition of mitochondrial translation by treatment with chloramphenicol markedly decreased ATP production and cell proliferation in DF-1 cells, while not affecting growth in either primary or other immortal CEF cells. This result suggests a correlation between rapid cell proliferation and the increased mitochondrial respiratory functions. We also determined that the increased transcription of mitochondrial-encoded genes in DF-1 cells is due to increased de novo transcript synthesis as shown by mitochondrial run-on assays, and not the result of either increased mitochondrial biogenesis or mitochondrial transcript half-lives. Together, the present studies suggest that the transcriptional activation of mitochondrial-encoded genes and the elevated respiratory function should be one of the characteristics of rapidly dividing immortal cells. Copyright 2001 Academic Press.

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice

PubMed Central

Safdar, Adeel; Bourgeois, Jacqueline M.; Ogborn, Daniel I.; Little, Jonathan P.; Hettinga, Bart P.; Akhtar, Mahmood; Thompson, James E.; Melov, Simon; Mocellin, Nicholas J.; Kujoth, Gregory C.; Prolla, Tomas A.; Tarnopolsky, Mark A.

2011-01-01

A causal role for mitochondrial DNA (mtDNA) mutagenesis in mammalian aging is supported by recent studies demonstrating that the mtDNA mutator mouse, harboring a defect in the proofreading-exonuclease activity of mitochondrial polymerase gamma, exhibits accelerated aging phenotypes characteristic of human aging, systemic mitochondrial dysfunction, multisystem pathology, and reduced lifespan. Epidemiologic studies in humans have demonstrated that endurance training reduces the risk of chronic diseases and extends life expectancy. Whether endurance exercise can attenuate the cumulative systemic decline observed in aging remains elusive. Here we show that 5 mo of endurance exercise induced systemic mitochondrial biogenesis, prevented mtDNA depletion and mutations, increased mitochondrial oxidative capacity and respiratory chain assembly, restored mitochondrial morphology, and blunted pathological levels of apoptosis in multiple tissues of mtDNA mutator mice. These adaptations conferred complete phenotypic protection, reduced multisystem pathology, and prevented premature mortality in these mice. The systemic mitochondrial rejuvenation through endurance exercise promises to be an effective therapeutic approach to mitigating mitochondrial dysfunction in aging and related comorbidities. PMID:21368114

Biogenesis of mitochondria in cauliflower (Brassica oleracea var. botrytis) curds subjected to temperature stress and recovery involves regulation of the complexome, respiratory chain activity, organellar translation and ultrastructure.

PubMed

Rurek, Michal; Woyda-Ploszczyca, Andrzej M; Jarmuszkiewicz, Wieslawa

2015-01-01

The biogenesis of the cauliflower curd mitochondrial proteome was investigated under cold, heat and the recovery. For the first time, two dimensional fluorescence difference gel electrophoresis was used to study the plant mitochondrial complexome in heat and heat recovery. Particularly, changes in the complex I and complex III subunits and import proteins, and the partial disintegration of matrix complexes were observed. The presence of unassembled subunits of ATP synthase was accompanied by impairment in mitochondrial translation of its subunit. In cold and heat, the transcription profiles of mitochondrial genes were uncorrelated. The in-gel activities of respiratory complexes were particularly affected after stress recovery. Despite a general stability of respiratory chain complexes in heat, functional studies showed that their activity and the ATP synthesis yield were affected. Contrary to cold stress, heat stress resulted in a reduced efficiency of oxidative phosphorylation likely due to changes in alternative oxidase (AOX) activity. Stress and stress recovery differently modulated the protein level and activity of AOX. Heat stress induced an increase in AOX activity and protein level, and AOX1a and AOX1d transcript level, while heat recovery reversed the AOX protein and activity changes. Conversely, cold stress led to a decrease in AOX activity (and protein level), which was reversed after cold recovery. Thus, cauliflower AOX is only induced by heat stress. In heat, contrary to the AOX activity, the activity of rotenone-insensitive internal NADH dehydrogenase was diminished. The relevance of various steps of plant mitochondrial biogenesis to temperature stress response and recovery is discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

EVALUATION OF THE BIOGENESIS SOIL WASHING TECHNOLOGY

EPA Science Inventory

The BioGenesis Enterprises, Inc. (BioGenesis) soil washing technology was demonstrated as part of the US Environmental Protection Agency's (EPA) Superfund Innovative Technology Evaluation (SITE) program in November 1992. The demonstration was conducted over three days at a petrol...

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.

A ketogenic diet accelerates neurodegeneration in mice with induced mitochondrial DNA toxicity in the forebrain.

PubMed

Lauritzen, Knut H; Hasan-Olive, Md Mahdi; Regnell, Christine E; Kleppa, Liv; Scheibye-Knudsen, Morten; Gjedde, Albert; Klungland, Arne; Bohr, Vilhelm A; Storm-Mathisen, Jon; Bergersen, Linda H

2016-12-01

Mitochondrial genome maintenance plays a central role in preserving brain health. We previously demonstrated accumulation of mitochondrial DNA damage and severe neurodegeneration in transgenic mice inducibly expressing a mutated mitochondrial DNA repair enzyme (mutUNG1) selectively in forebrain neurons. Here, we examine whether severe neurodegeneration in mutUNG1-expressing mice could be rescued by feeding the mice a ketogenic diet, which is known to have beneficial effects in several neurological disorders. The diet increased the levels of superoxide dismutase 2, and mitochondrial mass, enzymes, and regulators such as SIRT1 and FIS1, and appeared to downregulate N-methyl-D-aspartic acid (NMDA) receptor subunits NR2A/B and upregulate γ-aminobutyric acid A (GABA A ) receptor subunits α 1 . However, unexpectedly, the ketogenic diet aggravated neurodegeneration and mitochondrial deterioration. Electron microscopy showed structurally impaired mitochondria accumulating in neuronal perikarya. We propose that aggravation is caused by increased mitochondrial biogenesis of generally dysfunctional mitochondria. This study thereby questions the dogma that a ketogenic diet is unambiguously beneficial in mitochondrial disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

A ketogenic diet accelerates neurodegeneration in mice with induced mitochondrial DNA toxicity in the forebrain

PubMed Central

Lauritzen, Knut H.; Hasan-Olive, Md Mahdi; Regnell, Christine E.; Kleppa, Liv; Scheibye-Knudsen, Morten; Gjedde, Albert; Klungland, Arne; Bohr, Vilhelm A.; Storm-Mathisen, Jon; Bergersen, Linda H.

2017-01-01

Mitochondrial genome maintenance plays a central role in preserving brain health. We previously demonstrated accumulation of mitochondrial DNA damage and severe neurodegeneration in transgenic mice inducibly expressing a mutated mitochondrial DNA repair enzyme (mutUNG1) selectively in forebrain neurons. Here, we examine whether severe neurodegeneration in mutUNG1-expressing mice could be rescued by feeding the mice a ketogenic diet, which is known to have beneficial effects in several neurological disorders. The diet increased the levels of superoxide dismutase 2, and mitochondrial mass, enzymes, and regulators such as SIRT1 and FIS1, and appeared to downregulate N-methyl-D-aspartic acid (NMDA) receptor subunits NR2A/B and upregulate γ-aminobutyric acid A (GABAA) receptor subunits α1. However, unexpectedly, the ketogenic diet aggravated neurodegeneration and mitochondrial deterioration. Electron microscopy showed structurally impaired mitochondria accumulating in neuronal perikarya. We propose that aggravation is caused by increased mitochondrial biogenesis of generally dysfunctional mitochondria. This study thereby questions the dogma that a ketogenic diet is unambiguously beneficial in mitochondrial disorders. PMID:27639119

microRNA biogenesis and turnover in plants.

PubMed

Rogers, K; Chen, X

2012-01-01

microRNAs (miRNAs) are short RNAs that regulate gene expression in eukaryotes. The biogenesis and turnover of miRNAs determine their spatiotemporal accumulation within tissues. miRNA biogenesis is a multistep process that entails transcription, processing, nuclear export, and formation of the miRNA-ARGONAUTE complex. Factors that perform each of these steps have been identified. Generation of mature miRNAs from primary transcripts, i.e., miRNA processing, is a key step in miRNA biogenesis. Our understanding of miRNA processing has expanded beyond the enzyme that performs the reactions, as more and more additional factors that impact the efficiency and accuracy of miRNA processing are uncovered. In contrast to miRNA biogenesis, miRNA turnover is an important but poorly understood process that contributes to the steady-state levels of miRNAs. Enzymes responsible for miRNA degradation have only recently been identified. This review describes the processes of miRNA maturation and degradation in plants.

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.

Myopathy caused by mammalian target of rapamycin complex 1 (mTORC1) inactivation is not reversed by restoring mitochondrial function

PubMed Central

Romanino, Klaas; Mazelin, Laetitia; Albert, Verena; Conjard-Duplany, Agnès; Lin, Shuo; Bentzinger, C. Florian; Handschin, Christoph; Puigserver, Pere; Zorzato, Francesco; Schaeffer, Laurent; Gangloff, Yann-Gaël; Rüegg, Markus A.

2011-01-01

Mammalian target of rapamycin complex 1 (mTORC1) is central to the control of cell, organ, and body size. Skeletal muscle-specific inactivation of mTORC1 in mice results in smaller muscle fibers, fewer mitochondria, increased glycogen stores, and a progressive myopathy that causes premature death. In mTORC1-deficient muscles, peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), which regulates mitochondrial biogenesis and glucose homeostasis, is strongly down-regulated. Here we tested whether induction of mitochondrial biogenesis pharmacologically or by the overexpression of PGC-1α is sufficient to reverse the phenotype of mice deficient for mTORC1. We show that both approaches normalize mitochondrial function, such as oxidative capacity and expression of mitochondrial genes. However, they do not prevent or delay the progressive myopathy. In addition, we find that mTORC1 has a much stronger effect than PGC-1α on the glycogen content in muscle. This effect is based on the strong activation of PKB/Akt in mTORC1-deficient mice. We also show that activation of PKB/Akt not only affects glycogen synthesis but also diminishes glycogen degradation. Thus, our work provides strong functional evidence that mitochondrial dysfunction in mice with inactivated mTORC1 signaling is caused by the down-regulation of PGC-1α. However, our data also show that the impairment of mitochondria does not lead directly to the lethal myopathy. PMID:22143799

Mitochondrial Translation and Beyond: Processes Implicated in Combined Oxidative Phosphorylation Deficiencies

PubMed Central

Smits, Paulien; Smeitink, Jan; van den Heuvel, Lambert

2010-01-01

Mitochondrial disorders are a heterogeneous group of often multisystemic and early fatal diseases, which are amongst the most common inherited human diseases. These disorders are caused by defects in the oxidative phosphorylation (OXPHOS) system, which comprises five multisubunit enzyme complexes encoded by both the nuclear and the mitochondrial genomes. Due to the multitude of proteins and intricacy of the processes required for a properly functioning OXPHOS system, identifying the genetic defect that underlies an OXPHOS deficiency is not an easy task, especially in the case of combined OXPHOS defects. In the present communication we give an extensive overview of the proteins and processes (in)directly involved in mitochondrial translation and the biogenesis of the OXPHOS system and their roles in combined OXPHOS deficiencies. This knowledge is important for further research into the genetic causes, with the ultimate goal to effectively prevent and cure these complex and often devastating disorders. PMID:20396601

Impaired Mitochondrial Biogenesis Precedes Heart Failure in Right Ventricular Hypertrophy in Congenital Heart Disease

PubMed Central

Karamanlidis, Georgios; Bautista-Hernandez, Victor; Fynn-Thompson, Francis; Nido, Pedro del; Tian, Rong

2011-01-01

Background The outcome of the surgical repair in congenital heart disease (CHD) correlates with the degree of myocardial damage. In this study we determined whether mitochondrial DNA depletion is a sensitive marker of right ventricular (RV) damage and whether impaired mitochondrial DNA (mtDNA) replication contributes to the transition from compensated hypertrophy to failure. Methods and Results RV samples obtained from 31 patients undergoing cardiac surgery were compared to 5 RV samples from non-failing hearts (control). Patients were divided into compensated hypertrophy and failure groups based on preoperative echocardiography, catheterization and/or MRI data. Mitochondrial enzyme activities (citrate synthase and succinate dehydrogenase) were maintained during hypertrophy and decreased by ~40% (p<0.05 vs. control) at the stage of failure. In contrast, mtDNA content was progressively decreased in the hypertrophied RV through failure (by 28±8% and 67±11% respectively, p<0.05 for both), whereas mtDNA encoded gene expression was sustained by increased transcriptional activity during compensated hypertrophy but not in failure. MtDNA depletion was attributed to reduced mtDNA replication in both hypertrophied and failing RV and it was independent of PGC-1 down-regulation but was accompanied by reduced expression of proteins constituting the mtDNA replication fork. Decreased mtDNA content in compensated hypertrophy was also associated with pathological changes of mitochondria ultrastructure. Conclusions Impaired mtDNA replication causes early and progressive depletion of mtDNA in the RV of the CHD patients during the transition from hypertrophy to failure. Decreased mtDNA content is likely a sensitive marker of mitochondrial injury in this patient population. PMID:21840936

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

PubMed

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

2017-11-04

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

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

PubMed Central

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

2015-01-01

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

Alternative splicing suggests extended function of PEX26 in peroxisome biogenesis.

PubMed

Weller, Sabine; Cajigas, Ivelisse; Morrell, James; Obie, Cassandra; Steel, Gary; Gould, Stephen J; Valle, David

2005-06-01

Matsumoto and colleagues recently identified PEX26 as the gene responsible for complementation group 8 of the peroxisome biogenesis disorders and showed that it encodes an integral peroxisomal membrane protein with a single C-terminal transmembrane domain and a cytosolic N-terminus that interacts with the PEX1/PEX6 heterodimer through direct binding to the latter. They proposed that PEX26 functions as the peroxisomal docking factor for the PEX1/PEX6 heterodimer. Here, we identify new PEX26 disease alleles, localize the PEX6-binding domain to the N-terminal half of the protein (aa 29-174), and show that, at the cellular level, PEX26 deficiency impairs peroxisomal import of both PTS1- and PTS2-targeted matrix proteins. Also, we find that PEX26 undergoes alternative splicing to produce several splice forms--including one, PEX26- delta ex5, that maintains frame and encodes an isoform lacking the transmembrane domain of full-length PEX26 (PEX26-FL). Despite its cytosolic location, PEX26- delta ex5 rescues peroxisome biogenesis in PEX26-deficient cells as efficiently as does PEX26-FL. To test our observation that a peroxisomal location is not required for PEX26 function, we made a chimeric protein (PEX26-Mito) with PEX26 as its N-terminus and the targeting segment of a mitochondrial outer membrane protein (OMP25) at its C-terminus. We found PEX26-Mito localized to the mitochondria and directed all detectable PEX6 and a fraction of PEX1 to this extraperoxisomal location; yet PEX26-Mito retains the full ability to rescue peroxisome biogenesis in PEX26-deficient cells. On the basis of these observations, we suggest that a peroxisomal localization of PEX26 and PEX6 is not required for their function and that the interaction of PEX6 with PEX1 is dynamic. This model predicts that, once activated in an extraperoxisomal location, PEX1 moves to the peroxisome and completes the function of the PEX1/6 heterodimer.

Pyruvate kinase M knockdown-induced signaling via AMP-activated protein kinase promotes mitochondrial biogenesis, autophagy, and cancer cell survival.

PubMed

Prakasam, Gopinath; Singh, Rajnish Kumar; Iqbal, Mohammad Askandar; Saini, Sunil Kumar; Tiku, Ashu Bhan; Bamezai, Rameshwar N K

2017-09-15

Preferential expression of the low-activity (dimeric) M2 isoform of pyruvate kinase (PK) over its constitutively active splice variant M1 isoform is considered critical for aerobic glycolysis in cancer cells. However, our results reported here indicate co-expression of PKM1 and PKM2 and their possible physical interaction in cancer cells. We show that knockdown of either PKM1 or PKM2 differentially affects net PK activity, viability, and cellular ATP levels of the lung carcinoma cell lines H1299 and A549. The stable knockdown of PK isoforms in A549 cells significantly reduced the cellular ATP level, whereas in H1299 cells the level of ATP was unaltered. Interestingly, the PKM1/2 knockdown in H1299 cells activated AMP-activated protein kinase (AMPK) signaling and stimulated mitochondrial biogenesis and autophagy to maintain energy homeostasis. In contrast, knocking down either of the PKM isoforms in A549 cells lacking LKB1, a serine/threonine protein kinase upstream of AMPK, failed to activate AMPK and sustain energy homeostasis and resulted in apoptosis. Moreover, in a similar genetic background of silenced PKM1 or PKM2, the knocking down of AMPKα1/2 catalytic subunit in H1299 cells induced apoptosis. Our findings help explain why previous targeting of PKM2 in cancer cells to control tumor growth has not met with the expected success. We suggest that this lack of success is because of AMPK-mediated energy metabolism rewiring, protecting cancer cell viability. On the basis of our observations, we propose an alternative therapeutic strategy of silencing either of the PKM isoforms along with AMPK in tumors. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Fisetin Confers Cardioprotection against Myocardial Ischemia Reperfusion Injury by Suppressing Mitochondrial Oxidative Stress and Mitochondrial Dysfunction and Inhibiting Glycogen Synthase Kinase 3β Activity.

PubMed

Shanmugam, Karthi; Ravindran, Sriram; Kurian, Gino A; Rajesh, Mohanraj

2018-01-01

Acute myocardial infarction (AMI) is the leading cause of morbidity and mortality worldwide. Timely reperfusion is considered an optimal treatment for AMI. Paradoxically, the procedure of reperfusion can itself cause myocardial tissue injury. Therefore, a strategy to minimize the reperfusion-induced myocardial tissue injury is vital for salvaging the healthy myocardium. Herein, we investigated the cardioprotective effects of fisetin, a natural flavonoid, against ischemia/reperfusion (I/R) injury (IRI) using a Langendorff isolated heart perfusion system. I/R produced significant myocardial tissue injury, which was characterized by elevated levels of lactate dehydrogenase and creatine kinase in the perfusate and decreased indices of hemodynamic parameters. Furthermore, I/R resulted in elevated oxidative stress, uncoupling of the mitochondrial electron transport chain, increased mitochondrial swelling, a decrease of the mitochondrial membrane potential, and induction of apoptosis. Moreover, IRI was associated with a loss of the mitochondrial structure and decreased mitochondrial biogenesis. However, when the animals were pretreated with fisetin, it significantly attenuated the I/R-induced myocardial tissue injury, blunted the oxidative stress, and restored the structure and function of mitochondria. Mechanistically, the fisetin effects were found to be mediated via inhibition of glycogen synthase kinase 3 β (GSK3 β ), which was confirmed by a biochemical assay and molecular docking studies.

The mitochondrial outer membrane protein MDI promotes local protein synthesis and mtDNA replication.

PubMed

Zhang, Yi; Chen, Yong; Gucek, Marjan; Xu, Hong

2016-05-17

Early embryonic development features rapid nuclear DNA replication cycles, but lacks mtDNA replication. To meet the high-energy demands of embryogenesis, mature oocytes are furnished with vast amounts of mitochondria and mtDNA However, the cellular machinery driving massive mtDNA replication in ovaries remains unknown. Here, we describe a Drosophila AKAP protein, MDI that recruits a translation stimulator, La-related protein (Larp), to the mitochondrial outer membrane in ovaries. The MDI-Larp complex promotes the synthesis of a subset of nuclear-encoded mitochondrial proteins by cytosolic ribosomes on the mitochondrial surface. MDI-Larp's targets include mtDNA replication factors, mitochondrial ribosomal proteins, and electron-transport chain subunits. Lack of MDI abolishes mtDNA replication in ovaries, which leads to mtDNA deficiency in mature eggs. Targeting Larp to the mitochondrial outer membrane independently of MDI restores local protein synthesis and rescues the phenotypes of mdi mutant flies. Our work suggests that a selective translational boost by the MDI-Larp complex on the outer mitochondrial membrane might be essential for mtDNA replication and mitochondrial biogenesis during oogenesis. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

The iron-binding CyaY and IscX proteins assist the ISC-catalyzed Fe-S biogenesis in Escherichia coli.

PubMed

Roche, Béatrice; Huguenot, Allison; Barras, Frédéric; Py, Béatrice

2015-02-01

In eukaryotes, frataxin deficiency (FXN) causes severe phenotypes including loss of iron-sulfur (Fe-S) cluster protein activity, accumulation of mitochondrial iron and leads to the neurodegenerative disease Friedreich's ataxia. In contrast, in prokaryotes, deficiency in the FXN homolog, CyaY, was reported not to cause any significant phenotype, questioning both its importance and its actual contribution to Fe-S cluster biogenesis. Because FXN is conserved between eukaryotes and prokaryotes, this surprising discrepancy prompted us to reinvestigate the role of CyaY in Escherichia coli. We report that CyaY (i) potentiates E. coli fitness, (ii) belongs to the ISC pathway catalyzing the maturation of Fe-S cluster-containing proteins and (iii) requires iron-rich conditions for its contribution to be significant. A genetic interaction was discovered between cyaY and iscX, the last gene of the isc operon. Deletion of both genes showed an additive effect on Fe-S cluster protein maturation, which led, among others, to increased resistance to aminoglycosides and increased sensitivity to lambda phage infection. Together, these in vivo results establish the importance of CyaY as a member of the ISC-mediated Fe-S cluster biogenesis pathway in E. coli, like it does in eukaryotes, and validate IscX as a new bona fide Fe-S cluster biogenesis factor. © 2014 John Wiley & Sons Ltd.

Metabolic Dysfunction Consistent with Premature Aging Results from Deletion of Pim Kinases

PubMed Central

Din, Shabana; Konstandin, Mathias H; Johnson, Bevan; Emathinger, Jacqueline; Völkers, Mirko; Toko, Haruhiro; Collins, Brett; Ormachea, Lucy; Samse, Kaitlen; Kubli, Dieter A; De La Torre, Andrea; Kraft, Andrew S; Gustafsson, Asa B; Kelly, Daniel P; Sussman, Mark A

2014-01-01

Rationale The senescent cardiac phenotype is accompanied by changes in mitochondrial function and biogenesis causing impairment in energy provision. The relationship between myocardial senescence and Pim kinases deserves attention since Pim-1 kinase is cardioprotective, in part, by preservation of mitochondrial integrity. Study of the pathological effects resulting from genetic deletion of all Pim kinase family members could provide important insight regarding cardiac mitochondrial biology and the aging phenotype. Objective Demonstrate myocardial senescence is promoted by loss of Pim leading to premature aging and aberrant mitochondrial function. Methods and Results Cardiac myocyte senescence was evident at three months of age in Pim Triple KnockOut (PTKO) mice, where all three isoforms of Pim kinase family members are genetically deleted. Cellular hypertrophic remodeling and fetal gene program activation was followed by heart failure at six months in PTKO mice. Metabolic dysfunction is an underlying cause of cardiac senescence and instigates a decline in cardiac function. Altered mitochondrial morphology is evident consequential to Pim deletion together with decreased ATP levels and increased phosphorylated AMPK, exposing an energy deficiency in PTKO mice. Expression of the genes encoding master regulators of mitochondrial biogenesis, PPARγ coactivator-1 (PGC-1) α and β were diminished in PTKO hearts, as were downstream targets included in mitochondrial energy transduction, including fatty acid oxidation. Reversal of the dysregulated metabolic phenotype was observed by overexpressing c-Myc, a downstream target of Pim kinases. Conclusion Pim kinases prevent premature cardiac aging and maintain a healthy pool of functional mitochondria leading to efficient cellular energetics. PMID:24916111

Resveratrol and the mitochondria: From triggering the intrinsic apoptotic pathway to inducing mitochondrial biogenesis, a mechanistic view.

PubMed

de Oliveira, Marcos Roberto; Nabavi, Seyed Fazel; Manayi, Azadeh; Daglia, Maria; Hajheydari, Zohreh; Nabavi, Seyed Mohammad

2016-04-01

Mitochondria, the power plants of the cell, are known as a cross-road of different cellular signaling pathways. These cytoplasmic double-membraned organelles play a pivotal role in energy metabolism and regulate calcium flux in the cells. It is well known that mitochondrial dysfunction is associated with different diseases such as neurodegeneration and cancer. A growing body of literature has shown that polyphenolic compounds exert direct effects on mitochondrial ultra-structure and function. Resveratrol is known as one of the most common bioactive constituents of red wine, which improves mitochondrial functions under in vitro and in vivo conditions. This paper aims to review the molecular pathways underlying the beneficial effects of resveratrol on mitochondrial structure and functions. In addition, we discuss the chemistry and main sources of resveratrol. Resveratrol represents the promising effects on mitochondria in different experimental models. However, there are several reports on the detrimental effects elicited by resveratrol on mitochondria. An understanding of the chemistry and source of resveratrol, its bioavailability and the promising effects on mitochondria brings a new hope to therapy of mitochondrial dysfunction-related diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Tob38, a novel essential component in the biogenesis of β-barrel proteins of mitochondria

PubMed Central

Waizenegger, Thomas; Habib, Shukry J; Lech, Maciej; Mokranjac, Dejana; Paschen, Stefan A; Hell, Kai; Neupert, Walter; Rapaport, Doron

2004-01-01

Insertion of β-barrel proteins into the outer membrane of mitochondria is mediated by the TOB complex. Known constituents of this complex are Tob55 and Mas37. We identified a novel component, Tob38. It is essential for viability of yeast and the function of the TOB complex. Tob38 is exposed on the surface of the mitochondrial outer membrane. It interacts with Mas37 and Tob55 and is associated with Tob55 even in the absence of Mas37. The Tob38–Tob55 core complex binds precursors of β-barrel proteins and facilitates their insertion into the outer membrane. Depletion of Tob38 results in strongly reduced levels of Tob55 and Mas37 and the residual proteins no longer form a complex. Tob38-depleted mitochondria are deficient in the import of β-barrel precursor proteins, but not of other outer membrane proteins or proteins of other mitochondrial subcompartments. We conclude that Tob38 has a crucial function in the biogenesis of β-barrel proteins of mitochondria. PMID:15205677

Mitochondria-targeted esculetin alleviates mitochondrial dysfunction by AMPK-mediated nitric oxide and SIRT3 regulation in endothelial cells: potential implications in atherosclerosis.

PubMed

Karnewar, Santosh; Vasamsetti, Sathish Babu; Gopoju, Raja; Kanugula, Anantha Koteswararao; Ganji, Sai Krishna; Prabhakar, Sripadi; Rangaraj, Nandini; Tupperwar, Nitin; Kumar, Jerald Mahesh; Kotamraju, Srigiridhar

2016-04-11

Mitochondria-targeted compounds are emerging as a new class of drugs that can potentially alter the pathophysiology of those diseases where mitochondrial dysfunction plays a critical role. We have synthesized a novel mitochondria-targeted esculetin (Mito-Esc) with an aim to investigate its effect during oxidative stress-induced endothelial cell death and angiotensin (Ang)-II-induced atherosclerosis in ApoE(-/-) mice. Mito-Esc but not natural esculetin treatment significantly inhibited H2O2- and Ang-II-induced cell death in human aortic endothelial cells by enhancing NO production via AMPK-mediated eNOS phosphorylation. While L-NAME (NOS inhibitor) significantly abrogated Mito-Esc-mediated protective effects, Compound c (inhibitor of AMPK) significantly decreased Mito-Esc-mediated increase in NO production. Notably, Mito-Esc promoted mitochondrial biogenesis by enhancing SIRT3 expression through AMPK activation; and restored H2O2-induced inhibition of mitochondrial respiration. siSIRT3 treatment not only completely reversed Mito-Esc-mediated mitochondrial biogenetic marker expressions but also caused endothelial cell death. Furthermore, Mito-Esc administration to ApoE(-/-) mice greatly alleviated Ang-II-induced atheromatous plaque formation, monocyte infiltration and serum pro-inflammatory cytokines levels. We conclude that Mito-Esc is preferentially taken up by the mitochondria and preserves endothelial cell survival during oxidative stress by modulating NO generation via AMPK. Also, Mito-Esc-induced SIRT3 plays a pivotal role in mediating mitochondrial biogenesis and perhaps contributes to its anti-atherogenic effects.

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

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

PubMed

Qiu, Linan; Luo, Yuju; Chen, Xiaojuan

2018-07-01

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

Methyl pyruvate rescues mitochondrial damage caused by SIGMAR1 mutation related to amyotrophic lateral sclerosis.

PubMed

Tagashira, Hideaki; Shinoda, Yasuharu; Shioda, Norifumi; Fukunaga, Kohji

2014-12-01

Amyotrophic lateral sclerosis (ALS) is a disease caused by motor neuron degeneration. Recently, a novel SIGMAR1 gene variant (p.E102Q) was discovered in some familial ALS patients. We address mechanisms underlying neurodegeneration caused by the mutation using Neuro2A cells overexpressing σ1R(E102Q), a protein of a SIGMAR1 gene variant (p.E102Q) and evaluate potential amelioration by ATP production via methyl pyruvate (MP) treatment. σ1R(E102Q) overexpression promoted dissociation of the protein from the endoplasmic reticulum (ER) membrane and cytoplasmic aggregation, which in turn impaired mitochondrial ATP production and proteasome activity. Under ER stress conditions, overexpression of wild-type σ1R suppressed ER stress-induced mitochondrial injury, whereas σ1R(E102Q) overexpression aggravated mitochondrial damage and induced autophagic cell death. Moreover, σ1R(E102Q)-overexpressing cells showed aberrant extra-nuclear localization of the TAR DNA-binding protein (TDP-43), a condition exacerbated by ER stress. Treatment of cells with the mitochondrial Ca(2+) transporter inhibitor Ru360 mimicked the effects of σ1R(E102Q) overexpression, indicating that aberrant σ1R-mediated mitochondrial Ca(2+) transport likely underlies TDP-43 extra-nuclear localization, segregation in inclusion bodies, and ubiquitination. Finally, enhanced ATP production promoted by methyl pyruvate (MP) treatment rescued proteasome impairment and TDP-43 extra-nuclear localization caused by σ1R(E102Q) overexpression. Our observations suggest that neurodegeneration seen in some forms of ALS are due in part to aberrant mitochondrial ATP production and proteasome activity as well as TDP-43 mislocalization resulting from the SIGMAR1 mutation. ATP supplementation by MP represents a potential therapeutic strategy to treat ALS caused by SIGMAR1 mutation. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of Nfu1 and Bol3 in iron-sulfur cluster transfer to mitochondrial clients

PubMed Central

Melber, Andrew; Na, Un; Vashisht, Ajay; Weiler, Benjamin D; Lill, Roland; Wohlschlegel, James A; Winge, Dennis R

2016-01-01

Iron-sulfur (Fe-S) clusters are essential for many cellular processes, ranging from aerobic respiration, metabolite biosynthesis, ribosome assembly and DNA repair. Mutations in NFU1 and BOLA3 have been linked to genetic diseases with defects in mitochondrial Fe-S centers. Through genetic studies in yeast, we demonstrate that Nfu1 functions in a late step of [4Fe-4S] cluster biogenesis that is of heightened importance during oxidative metabolism. Proteomic studies revealed Nfu1 physical interacts with components of the ISA [4Fe-4S] assembly complex and client proteins that need [4Fe-4S] clusters to function. Additional studies focused on the mitochondrial BolA proteins, Bol1 and Bol3 (yeast homolog to human BOLA3), revealing that Bol1 functions earlier in Fe-S biogenesis with the monothiol glutaredoxin, Grx5, and Bol3 functions late with Nfu1. Given these observations, we propose that Nfu1, assisted by Bol3, functions to facilitate Fe-S transfer from the biosynthetic apparatus to the client proteins preventing oxidative damage to [4Fe-4S] clusters. DOI: http://dx.doi.org/10.7554/eLife.15991.001 PMID:27532773

Eicosapentaenoic acid but not docosahexaenoic acid restores skeletal muscle mitochondrial oxidative capacity in old mice

PubMed Central

Johnson, Matthew L; Lalia, Antigoni Z; Dasari, Surendra; Pallauf, Maximilian; Fitch, Mark; Hellerstein, Marc K; Lanza, Ian R

2015-01-01

Mitochondrial dysfunction is often observed in aging skeletal muscle and is implicated in age-related declines in physical function. Early evidence suggests that dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve mitochondrial function. Here, we show that 10 weeks of dietary eicosapentaenoic acid (EPA) supplementation partially attenuated the age-related decline in mitochondrial function in mice, but this effect was not observed with docosahexaenoic acid (DHA). The improvement in mitochondrial function with EPA occurred in the absence of any changes in mitochondrial abundance or biogenesis, which was evaluated from RNA sequencing, large-scale proteomics, and direct measurements of muscle mitochondrial protein synthesis rates. We find that EPA improves muscle protein quality, specifically by decreasing mitochondrial protein carbamylation, a post-translational modification that is driven by inflammation. These results demonstrate that EPA attenuated the age-related loss of mitochondrial function and improved mitochondrial protein quality through a mechanism that is likely linked with anti-inflammatory properties of n-3 PUFAs. Furthermore, we demonstrate that EPA and DHA exert some common biological effects (anticoagulation, anti-inflammatory, reduced FXR/RXR activation), but also exhibit many distinct biological effects, a finding that underscores the importance of evaluating the therapeutic potential of individual n-3 PUFAs. PMID:26010060

Mitochondrial function at extreme high altitude.

PubMed

Murray, Andrew J; Horscroft, James A

2016-03-01

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

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

Downregulation of ribosome biogenesis during early forebrain development

PubMed Central

Chau, Kevin F; Shannon, Morgan L; Fame, Ryann M; Fonseca, Erin; Mullan, Hillary; Johnson, Matthew B; Sendamarai, Anoop K; Springel, Mark W; Laurent, Benoit

2018-01-01

Forebrain precursor cells are dynamic during early brain development, yet the underlying molecular changes remain elusive. We observed major differences in transcriptional signatures of precursor cells from mouse forebrain at embryonic days E8.5 vs. E10.5 (before vs. after neural tube closure). Genes encoding protein biosynthetic machinery were strongly downregulated at E10.5. This was matched by decreases in ribosome biogenesis and protein synthesis, together with age-related changes in proteomic content of the adjacent fluids. Notably, c-MYC expression and mTOR pathway signaling were also decreased at E10.5, providing potential drivers for the effects on ribosome biogenesis and protein synthesis. Interference with c-MYC at E8.5 prematurely decreased ribosome biogenesis, while persistent c-MYC expression in cortical progenitors increased transcription of protein biosynthetic machinery and enhanced ribosome biogenesis, as well as enhanced progenitor proliferation leading to subsequent macrocephaly. These findings indicate large, coordinated changes in molecular machinery of forebrain precursors during early brain development. PMID:29745900

Increases in Intracellular Zinc Enhance Proliferative Signaling as well as Mitochondrial and Endolysosomal Activity in Human Melanocytes.

PubMed

Rudolf, Emil; Rudolf, Kamil

2017-01-01

Zinc (Zn) is an important microelement required by skin cells for a variety of biological processes. The role of Zn in melanocyte proliferation and homeostasis has to date not been investigated. Human dermal melanocytes were isolated from patients and their proliferative activity determined along with both total and labile Zn content. Subsequently, changes in proliferation as well as in Zn content were determined upon exposure of the dermal melanocytes to external Zn. Further in-depth analyses were undertaken aimed at measuring the expression of proliferation-related proteins (determined by immunoblotting and densitometry), as well as changes in mitochondrial biogenesis and membrane potential (assessed by fluorescence-based cellometry) along with endolysosomal activity (determined by spectrofluorimetrically-measured elevation in fluorescence of lysosomal-aimed non-fuorescent substrate). Human skin melanocytes accumulate externally added Zn, a process which dose-dependently enhances their injury or proliferative activity. Enhanced proliferation is accompanied by an increased expression of the proteins AKT3, ERK1/2, c-MYC and CYCD. In addition, Zn-enriched melanocytes exhibit enhanced mitochondrial biogenesis, with individual mitochondria possessing stabilized mitochondrial membrane potential as well as showing elevated ATP and superoxide levels. Moreover, upon external exposure, Zn enters lysosomes/melanosomes, the activity of which is stimulated along with the process of autophagy. The determination of the unique Zn-dependent stimulation of melanocytes and in particular the enhancement of the cells' mitochondrial as well as lysosomal/melanosomal activities may prove important in tracing the sequence of steps in the process of melanomagenesis. © 2017 The Author(s). Published by S. Karger AG, Basel.

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

Mutations in mitochondrial complex I assembly factor NDUFAF3 cause Leigh syndrome.

PubMed

Baertling, Fabian; Sánchez-Caballero, Laura; Timal, Sharita; van den Brand, Mariël Am; Ngu, Lock Hock; Distelmaier, Felix; Rodenburg, Richard Jt; Nijtmans, Leo Gj

2017-03-01

NDUFAF3 is an assembly factor of mitochondrial respiratory chain complex I. Variants in NDUFAF3 have been identified as a cause of severe multisystem mitochondrial disease. In a patient presenting with Leigh syndrome, which has hitherto not been described as a clinical feature of NDUFAF3 deficiency, we identified a novel homozygous variant and confirmed its pathogenicity in patient fibroblasts studies. Furthermore, we present an analysis of complex I assembly routes representative of each functional module and, thereby, link NDUFAF3 to a specific step in complex I assembly. Therefore, our report expands the phenotype of NDUFAF3 deficiency and further characterizes the role of NDUFAF3 in complex I biogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial-epigenetic crosstalk in environmental toxicology.

PubMed

Weinhouse, Caren

2017-11-01

Crosstalk between the nuclear epigenome and mitochondria, both in normal physiological function and in responses to environmental toxicant exposures, is a developing sub-field of interest in environmental and molecular toxicology. The majority (∼99%) of mitochondrial proteins are encoded in the nuclear genome, so programmed communication among nuclear, cytoplasmic, and mitochondrial compartments is essential for maintaining cellular health. In this review, we will focus on correlative and mechanistic evidence for direct impacts of each system on the other, discuss demonstrated or potential crosstalk in the context of chemical insult, and highlight biological research questions for future study. We will first review the two main signaling systems: nuclear signaling to the mitochondria [anterograde signaling], best described in regulation of oxidative phosphorylation (OXPHOS) and mitochondrial biogenesis in response to environmental signals received by the nucleus, and mitochondrial signals to the nucleus [retrograde signaling]. Both signaling systems can communicate intracellular energy needs or a need to compensate for dysfunction to maintain homeostasis, but both can also relay inappropriate signals in the presence of dysfunction in either system and contribute to adverse health outcomes. We will first review these two signaling systems and highlight known or biologically feasible epigenetic contributions to both, then briefly discuss the emerging field of epigenetic regulation of the mitochondrial genome, and finally discuss putative "crosstalk phenotypes", including biological phenomena, such as caloric restriction, maintenance of stemness, and circadian rhythm, and states of disease or loss of function, such as cancer and aging, in which both the nuclear epigenome and mitochondria are strongly implicated. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of alpha-melanocyte-stimulating hormone on mitochondrial energy metabolism in rats of different age-groups.

PubMed

Feichtinger, René G; Pétervári, Erika; Zopf, Michaela; Vidali, Silvia; Aminzadeh-Gohari, Sepideh; Mayr, Johannes A; Kofler, Barbara; Balaskó, Márta

2017-08-01

Hypothalamic alpha-melanocyte-stimulating hormone (α-MSH) is a key catabolic mediator of energy homeostasis. Its anorexigenic and hypermetabolic effects show characteristic age-related alterations that may be part of the mechanism of middle-aged obesity and geriatric anorexia/cachexia seen in humans and other mammals. We aimed to investigate the role of α-MSH in mitochondrial energy metabolism during the course of aging in a rodent model. To determine the role of α-MSH in mitochondrial energy metabolism in muscle, we administered intracerebroventricular (ICV) infusions of α-MSH for 7-days to different age-groups of male Wistar rats. The activities of oxidative phosphorylation complexes I to V and citrate synthase were determined and compared to those of age-matched controls. We also quantified mitochondrial DNA (mtDNA) copy number and measured the expression of the master regulators of mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and peroxisome proliferator-activated receptor gamma (PPARγ). The peptide reduced weight gain in juvenile rats to one fifth of that of controls and increased the weight loss in older animals by about five fold. Mitochondrial DNA copy number inversely correlated with changes in body weight in controls, but not in α-MSH-treated animals. The strong increase in body weight in young rats was associated with a low mtDNA copy number and high PPARγ mRNA levels in controls. Expression of PGC-1α and PPARγ declined with age, whereas OXPHOS and citrate synthase enzyme activities were unchanged. In contrast, α-MSH treatment suppressed OXPHOS enzyme and citrate synthase activity. In conclusion, our results showed age-related differences in the metabolic effects of α-MSH. In addition, administration of α-MSH suppressed citrate synthase and OXPHOS activities independent of age. These findings suggest that α-MSH exposure may inhibit mitochondrial biogenesis. Copyright © 2016 Elsevier

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

From centriole biogenesis to cellular function: centrioles are essential for cell division at critical developmental stages.

PubMed

Rodrigues-Martins, Ana; Riparbelli, Maria; Callaini, Giuliano; Glover, David M; Bettencourt-Dias, Monica

2008-01-01

Centrioles are essential for the formation of cilia, flagella and centrosome organization. Abnormalities in centrosome structure and number in many cancers can be associated with aberrant cell division and genomic instability.(1,2) Canonical centriole duplication occurs in coordination with the cell division cycle, such that a single new "daughter" centriole arises next to each "mother" centriole. If destroyed, or eliminated during development, centrioles can form de novo.(3-5) Here we discuss our recent data demonstrating a molecular pathway that operates in both de novo and canonical centriole biogenesis involving SAK/PLK4, SAS-6 and SAS-4.(6) We showed that centriole biogenesis is a self-assembly process locally triggered by high SAK/PLK4 activity that may or not be associated with an existing centriole. SAS-6 acts downstream of SAK/PLK4 to organize nine precentriolar units, which we call here enatosomes, fitting together laterally and longitudinally, specifying a tube-like centriole precursor.(7,8) The identification of mutants impaired in centriole biogenesis has permitted the study of the physiological consequences of their absence in the whole organism. In Drosophila, centrioles are not necessary for somatic cell divisions.(9,10) However, we show here that mitotic abnormalities arise in syncytial SAK/PLK4-derived mutant embryos resulting in lethality. Moreover male meiosis fails in both SAK/PLK4 and DSAS-4 mutant spermatids that have no centrioles. These results show diversity in the need for centrioles in cell division. This suggests that tissue specific constraints selected for different contributions of centrosome-independent and dependent mechanisms in spindle function. This heterogeneity should be taken into account both in reaching an understanding of spindle function and when designing drugs that target cell division.

Reduced Glucose Sensation Can Increase the Fitness of Saccharomyces cerevisiae Lacking Mitochondrial DNA

PubMed Central

Akdoğan, Emel; Tardu, Mehmet; Garipler, Görkem; Baytek, Gülkız; Kavakli, İ. Halil; Dunn, Cory D.

2016-01-01

Damage to the mitochondrial genome (mtDNA) can lead to diseases for which there are no clearly effective treatments. Since mitochondrial function and biogenesis are controlled by the nutrient environment of the cell, it is possible that perturbation of conserved, nutrient-sensing pathways may successfully treat mitochondrial disease. We found that restricting glucose or otherwise reducing the activity of the protein kinase A (PKA) pathway can lead to improved proliferation of Saccharomyces cerevisiae cells lacking mtDNA and that the transcriptional response to mtDNA loss is reduced in cells with diminished PKA activity. We have excluded many pathways and proteins from being individually responsible for the benefits provided to cells lacking mtDNA by PKA inhibition, and we found that robust import of mitochondrial polytopic membrane proteins may be required in order for cells without mtDNA to receive the full benefits of PKA reduction. Finally, we have discovered that the transcription of genes involved in arginine biosynthesis and aromatic amino acid catabolism is altered after mtDNA damage. Our results highlight the potential importance of nutrient detection and availability on the outcome of mitochondrial dysfunction. PMID:26751567

PGC-1α Regulation of Mitochondrial Degeneration in Experimental Diabetic Neuropathy

PubMed Central

Choi, Joungil; Chandrasekaran, Krish; Inoue, Tatsuya; Muragundla, Anjaneyulu; Russell, James W.

2014-01-01

Mitochondrial degeneration is considered to play an important role in the development of diabetic peripheral neuropathy in humans. Mitochondrial degeneration and the corresponding protein regulation associated with the degeneration were studied in an animal model of diabetic neuropathy. PGC-1α and its-regulated transcription factors including TFAM and NRF1, which are master regulators of mitochondrial biogenesis, are significantly downregulated in streptozotocin diabetic dorsal root ganglion (DRG) neurons. Diabetic mice develop peripheral neuropathy, loss of mitochondria, decreased mitochondrial DNA content and increased protein oxidation. Importantly, this phenotype is exacerbated in PGC-1α (−/−) diabetic mice, which develop a more severe neuropathy with reduced mitochondrial DNA and a further increase in protein oxidation. PGC-1α (−/−) diabetic mice develop an increase in total cholesterol and triglycerides, and a decrease in TFAM and NRF1 protein levels. Loss of PGC-1α causes severe mitochondrial degeneration with vacuolization in DRG neurons, coupled with reduced state 3 and 4 respiration, reduced expression of oxidative stress response genes and an increase in protein oxidation. In contrast, overexpression of PGC-1α in cultured adult mouse neurons prevents oxidative stress associated with increased glucose levels. The study provides new insights into the role of PGC-1α in mitochondrial regeneration in peripheral neurons and suggests that therapeutic modulation of PGC-1α function may be an attractive approach for treatment of diabetic neuropathy. PMID:24423644

Liraglutide alleviates H2O2-induced retinal ganglion cells injury by inhibiting autophagy through mitochondrial pathways.

PubMed

Ma, Xuefei; Lin, Wenjian; Lin, Zhenyu; Hao, Ming; Gao, Xinyuan; Zhang, Yue; Kuang, Hongyu

2017-06-01

Retinal ganglion cells (RGCs), which exist in the inner retina, are the retinal neurons which can be damaged in the early stage of diabetic retinopathy (DR). Liraglutide, a glucagon-like peptide-1 (GLP-1) analog, exerts biological functions by binding the receptor (GLP-1R), the expression of which in RGC-5 cells was first shown by our team in 2012. It was reported that liraglutide prevented retinal neurodegeneration in diabetic subjects. However, the involvement of mechanisms such as autophagy and mitochondrial balance in liraglutide-induced retinal protection is unknown. Here, we aimed to investigate the protective effects of liraglutide and explore the potential mechanisms of liraglutide-induced retinal RGC protection. RGC-5 cells were treated with H 2 O 2 and/or liraglutide. Cell viability was detected with the CCK-8 kit. The axon marker GAP43, autophagy and mitophagy indicators LC3A/B, Beclin-1, p62, Parkin, BCL2/Adenovirus E1B 19kDa protein-interacting protein 3-like (BNIP3L) and the key regulator of mitochondrial biogenesis PGC-1α were examined via western blot analysis. Autophagy was also evaluated using the ImageXpress Micro XLS system and transmission electron microscopy (TEM). Reactive oxygen species (ROS), mitochondrial membrane potential and fluorescent staining for mitochondria were also measured using the ImageXpress Micro XLS system. Our results showed that pretreatment with liraglutide significantly prevented H 2 O 2 -induced cell viability decline, mitochondrial morphological deterioration and induction of autophagy, which appeared as increased expression of LC3 II/I and Beclin-1, along with p62 degradation. Moreover, liraglutide suppressed the H 2 O 2 -induced decline in GAP43 expression, thus protecting cells. However, rapamycin induced autophagy and blocked the protective process. Liraglutide also provided mitochondrial protection and appeared to alleviate H 2 O 2 -induced ROS overproduction and a decline in mitochondrial membrane potential

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.

Abnormal Mitochondrial Dynamics and Synaptic Degeneration as Early Events in Alzheimer’s Disease: Implications to Mitochondria-Targeted Antioxidant Therapeutics

PubMed Central

Reddy, P. Hemachandra; Tripathy, Raghav; Troung, Quang; Thirumala, Karuna; Reddy, Tejaswini P.; Anekonda, Vishwanath; Shirendeb, Ulziibat P.; Calkins, Marcus J.; Reddy, Arubala P.; Mao, Peizhong; Manczak, Maria

2011-01-01

Synaptic pathology and mitochondrial oxidative damage are early events in Alzheimer’s disease (AD) progression. Loss of synapses and synaptic damage are the best correlate of cognitive deficits found in AD patients. Recent research on amyloid bet (Aβ) and mitochondria in AD revealed that Aβ accumulates in synapses and synaptic mitochondria, leading to abnormal mitochondrial dynamics and synaptic degeneration in AD neurons. Further, recent studies using live-cell imaging and primary neurons from amyloid beta precursor protein (AβPP) transgenic mice revealed that reduced mitochondrial mass, defective axonal transport of mitochondria and synaptic degeneration, indicating that Aβ is responsible for mitochondrial and synaptic deficiencies. Tremendous progress has been made in studying antioxidant approaches in mouse models of AD and clinical trials of AD patients. This article highlights the recent developments made in Aβ-induced abnormal mitochondrial dynamics, defective mitochondrial biogenesis, impaired axonal transport and synaptic deficiencies in AD. This article also focuses on mitochondrial approaches in treating AD, and also discusses latest research on mitochondria-targeted antioxidants in AD. PMID:22037588

Posttranslational modification of mitochondrial transcription factor A in impaired mitochondria biogenesis: implications in diabetic retinopathy and metabolic memory phenomenon.

PubMed

Santos, Julia M; Mishra, Manish; Kowluru, Renu A

2014-04-01

Mitochondrial transcription factor A (TFAM) is one of the key regulators of the transcription of mtDNA. In diabetes, despite increase in gene transcripts of TFAM, its protein levels in the mitochondria are decreased and mitochondria copy numbers become subnormal. The aim of this study is to investigate the mechanism(s) responsible for decreased mitochondrial TFAM in diabetes. Using retinal endothelial cells, we have investigated the effect of overexpression of cytosolic chaperone, Hsp70, and TFAM on glucose-induced decrease in mitochondrial TFAM levels, and the transcription of mtDNA-encoded genes, NADH dehydrogenase subunit 6 (ND6) and cytochrome b (Cytb). To investigate the role of posttranslational modifications in subnormal mitochondrial TFAM, ubiquitination of TFAM was assessed, and the results were confirmed in the retina from streptozotocin-induced diabetic rats. While overexpression of Hsp70 failed to prevent glucose-induced decrease in mitochondrial TFAM and transcripts of ND6 and Cytb, overexpression of TFAM ameliorated decrease in its mitochondrial protein levels and transcriptional activity. TFAM was ubiquitinated by high glucose, and PYR-41, an inhibitor of ubiquitination, prevented TFAM ubiquitination and restored the transcriptional activity. Similarly, TFAM was ubiquitinated in the retina from diabetic rats, and it continued to be modified after reinstitution of normal glycemia. Our results clearly imply that the ubiquitination of TFAM impedes its transport to the mitochondria resulting in subnormal mtDNA transcription and mitochondria dysfunction, and inhibition of ubiquitination restores mitochondrial homeostasis. Reversal of hyperglycemia does not provide any benefit to TFAM ubiquitination. Thus, strategies targeting posttranslational modification could provide an avenue to preserve mitochondrial homeostasis, and inhibit the development/progression of diabetic retinopathy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cytochrome c Oxidase Biogenesis and Metallochaperone Interactions: Steps in the Assembly Pathway of a Bacterial Complex

PubMed Central

Ludwig, Bernd

2017-01-01

Biogenesis of mitochondrial cytochrome c oxidase (COX) is a complex process involving the coordinate expression and assembly of numerous subunits (SU) of dual genetic origin. Moreover, several auxiliary factors are required to recruit and insert the redox-active metal compounds, which in most cases are buried in their protein scaffold deep inside the membrane. Here we used a combination of gel electrophoresis and pull-down assay techniques in conjunction with immunostaining as well as complexome profiling to identify and analyze the composition of assembly intermediates in solubilized membranes of the bacterium Paracoccus denitrificans. Our results show that the central SUI passes through at least three intermediate complexes with distinct subunit and cofactor composition before formation of the holoenzyme and its subsequent integration into supercomplexes. We propose a model for COX biogenesis in which maturation of newly translated COX SUI is initially assisted by CtaG, a chaperone implicated in CuB site metallation, followed by the interaction with the heme chaperone Surf1c to populate the redox-active metal-heme centers in SUI. Only then the remaining smaller subunits are recruited to form the mature enzyme which ultimately associates with respiratory complexes I and III into supercomplexes. PMID:28107462

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

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

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

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

Eicosapentaenoic acid but not docosahexaenoic acid restores skeletal muscle mitochondrial oxidative capacity in old mice.

PubMed

Johnson, Matthew L; Lalia, Antigoni Z; Dasari, Surendra; Pallauf, Maximilian; Fitch, Mark; Hellerstein, Marc K; Lanza, Ian R

2015-10-01

Mitochondrial dysfunction is often observed in aging skeletal muscle and is implicated in age-related declines in physical function. Early evidence suggests that dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve mitochondrial function. Here, we show that 10 weeks of dietary eicosapentaenoic acid (EPA) supplementation partially attenuated the age-related decline in mitochondrial function in mice, but this effect was not observed with docosahexaenoic acid (DHA). The improvement in mitochondrial function with EPA occurred in the absence of any changes in mitochondrial abundance or biogenesis, which was evaluated from RNA sequencing, large-scale proteomics, and direct measurements of muscle mitochondrial protein synthesis rates. We find that EPA improves muscle protein quality, specifically by decreasing mitochondrial protein carbamylation, a post-translational modification that is driven by inflammation. These results demonstrate that EPA attenuated the age-related loss of mitochondrial function and improved mitochondrial protein quality through a mechanism that is likely linked with anti-inflammatory properties of n-3 PUFAs. Furthermore, we demonstrate that EPA and DHA exert some common biological effects (anticoagulation, anti-inflammatory, reduced FXR/RXR activation), but also exhibit many distinct biological effects, a finding that underscores the importance of evaluating the therapeutic potential of individual n-3 PUFAs. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

ES1 is a mitochondrial enlarging factor contributing to form mega-mitochondria in zebrafish cones.

PubMed

Masuda, Takamasa; Wada, Yasutaka; Kawamura, Satoru

2016-03-01

Total mass of mitochondria increases during cell proliferation and differentiation through mitochondrial biogenesis, which includes mitochondrial proliferation and growth. During the mitochondrial growth, individual mitochondria have been considered to be enlarged independently of mitochondrial fusion. However, molecular basis for this enlarging process has been poorly understood. Cone photoreceptor cells in the retina possess large mitochondria, so-called mega-mitochondria that have been considered to arise via the enlarging process. Here we show that ES1 is a novel mitochondria-enlarging factor contributing to form mega-mitochondria in cones. ES1 is specifically expressed in cones and localized to mitochondria including mega-mitochondria. Knockdown of ES1 markedly reduced the mitochondrial size in cones. In contrast, ectopic expression of ES1 in rods significantly increased both the size of individual mitochondria and the total mass of the mitochondrial cluster without changing the number of them. RNA-seq analysis showed that ERRα and its downstream mitochondrial genes were significantly up-regulated in the ES1-expressing rods, suggesting facilitation of mitochondrial enlargement via ERRα-dependent processes. Furthermore, higher energy state was detected in the ES1-expressing rods, indicating that the enlarged mitochondria by ES1 are capable of producing high energy. ES1 is the mitochondrial protein that is first found to promote enlargement of individual mitochondria.

Roles of mitochondrial fragmentation and reactive oxygen species in mitochondrial dysfunction and myocardial insulin resistance

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

Watanabe, Tomoyuki; Saotome, Masao, E-mail: msaotome@hama-med.ac.jp; Nobuhara, Mamoru

Purpose: Evidence suggests an association between aberrant mitochondrial dynamics and cardiac diseases. Because myocardial metabolic deficiency caused by insulin resistance plays a crucial role in heart disease, we investigated the role of dynamin-related protein-1 (DRP1; a mitochondrial fission protein) in the pathogenesis of myocardial insulin resistance. Methods and Results: DRP1-expressing H9c2 myocytes, which had fragmented mitochondria with mitochondrial membrane potential (ΔΨ{sub m}) depolarization, exhibited attenuated insulin signaling and 2-deoxy-D-glucose (2-DG) uptake, indicating insulin resistance. Treatment of the DRP1-expressing myocytes with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (TMPyP) significantly improved insulin resistance and mitochondrial dysfunction. When myocytes were exposed to hydrogen peroxide (H{sub 2}O{sub 2}),more » they increased DRP1 expression and mitochondrial fragmentation, resulting in ΔΨ{sub m} depolarization and insulin resistance. When DRP1 was suppressed by siRNA, H{sub 2}O{sub 2}-induced mitochondrial dysfunction and insulin resistance were restored. Our results suggest that a mutual enhancement between DRP1 and reactive oxygen species could induce mitochondrial dysfunction and myocardial insulin resistance. In palmitate-induced insulin-resistant myocytes, neither DRP1-suppression nor TMPyP restored the ΔΨ{sub m} depolarization and impaired 2-DG uptake, however they improved insulin signaling. Conclusions: A mutual enhancement between DRP1 and ROS could promote mitochondrial dysfunction and inhibition of insulin signal transduction. However, other mechanisms, including lipid metabolite-induced mitochondrial dysfunction, may be involved in palmitate-induced insulin resistance. - Highlights: • DRP1 promotes mitochondrial fragmentation and insulin-resistance. • A mutual enhancement between DRP1 and ROS ipromotes insulin-resistance. • Palmitate increases DRP1 expression and induces insulin

Parkin and PINK1 function in a vesicular trafficking pathway regulating mitochondrial quality control

PubMed Central

McLelland, Gian-Luca; Soubannier, Vincent; Chen, Carol X; McBride, Heidi M; Fon, Edward A

2014-01-01

Mitochondrial dysfunction has long been associated with Parkinson's disease (PD). Parkin and PINK1, two genes associated with familial PD, have been implicated in the degradation of depolarized mitochondria via autophagy (mitophagy). Here, we describe the involvement of parkin and PINK1 in a vesicular pathway regulating mitochondrial quality control. This pathway is distinct from canonical mitophagy and is triggered by the generation of oxidative stress from within mitochondria. Wild-type but not PD-linked mutant parkin supports the biogenesis of a population of mitochondria-derived vesicles (MDVs), which bud off mitochondria and contain a specific repertoire of cargo proteins. These MDVs require PINK1 expression and ultimately target to lysosomes for degradation. We hypothesize that loss of this parkin- and PINK1-dependent trafficking mechanism impairs the ability of mitochondria to selectively degrade oxidized and damaged proteins leading, over time, to the mitochondrial dysfunction noted in PD. PMID:24446486

Human mitochondrial disease-like symptoms caused by a reduced tRNA aminoacylation activity in flies

PubMed Central

Guitart, Tanit; Picchioni, Daria; Piñeyro, David; Ribas de Pouplana, Lluís

2013-01-01

The translation of genes encoded in the mitochondrial genome requires specific machinery that functions in the organelle. Among the many mutations linked to human disease that affect mitochondrial translation, several are localized to nuclear genes coding for mitochondrial aminoacyl-transfer RNA synthetases. The molecular significance of these mutations is poorly understood, but it is expected to be similar to that of the mutations affecting mitochondrial transfer RNAs. To better understand the molecular features of diseases caused by these mutations, and to improve their diagnosis and therapeutics, we have constructed a Drosophila melanogaster model disrupting the mitochondrial seryl-tRNA synthetase by RNA interference. At the molecular level, the knockdown generates a reduction in transfer RNA serylation, which correlates with the severity of the phenotype observed. The silencing compromises viability, longevity, motility and tissue development. At the cellular level, the knockdown alters mitochondrial morphology, biogenesis and function, and induces lactic acidosis and reactive oxygen species accumulation. We report that administration of antioxidant compounds has a palliative effect of some of these phenotypes. In conclusion, the fly model generated in this work reproduces typical characteristics of pathologies caused by mutations in the mitochondrial aminoacylation system, and can be useful to assess therapeutic approaches. PMID:23677612

Mechanism of Peptide Binding and Cleavage by the Human Mitochondrial Peptidase Neurolysin.

PubMed

Teixeira, Pedro F; Masuyer, Geoffrey; Pinho, Catarina M; Branca, Rui M M; Kmiec, Beata; Wallin, Cecilia; Wärmländer, Sebastian K T S; Berntsson, Ronnie P-A; Ankarcrona, Maria; Gräslund, Astrid; Lehtiö, Janne; Stenmark, Pål; Glaser, Elzbieta

2018-02-02

Proteolysis plays an important role in mitochondrial biogenesis, from the processing of newly imported precursor proteins to the degradation of mitochondrial targeting peptides. Disruption of peptide degradation activity in yeast, plant and mammalian mitochondria is known to have deleterious consequences for organism physiology, highlighting the important role of mitochondrial peptidases. In the present work, we show that the human mitochondrial peptidase neurolysin (hNLN) can degrade mitochondrial presequence peptides as well as other fragments up to 19 amino acids long. The crystal structure of hNLN E475Q in complex with the products of neurotensin cleavage at 2.7Å revealed a closed conformation with an internal cavity that restricts substrate length and highlighted the mechanism of enzyme opening/closing that is necessary for substrate binding and catalytic activity. Analysis of peptide degradation in vitro showed that hNLN cooperates with presequence protease (PreP or PITRM1) in the degradation of long targeting peptides and amyloid-β peptide, Aβ1-40, associated with Alzheimer disease, particularly cleaving the hydrophobic fragment Aβ35-40. These findings suggest that a network of proteases may be required for complete degradation of peptides localized in mitochondria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deficiency of PHB complex impairs respiratory supercomplex formation and activates mitochondrial flashes.

PubMed

Jian, Chongshu; Xu, Fengli; Hou, Tingting; Sun, Tao; Li, Jinghang; Cheng, Heping; Wang, Xianhua

2017-08-01

Prohibitins (PHBs; prohibitin 1, PHB1 or PHB, and prohibitin 2, PHB2) are evolutionarily conserved and ubiquitously expressed mitochondrial proteins. PHBs form multimeric ring complexes acting as scaffolds in the inner mitochondrial membrane. Mitochondrial flashes (mitoflashes) are newly discovered mitochondrial signaling events that reflect electrical and chemical excitations of the organelle. Here, we investigate the possible roles of PHBs in the regulation of mitoflash signaling. Downregulation of PHBs increases mitoflash frequency by up to 5.4-fold due to elevated basal reactive oxygen species (ROS) production in the mitochondria. Mechanistically, PHB deficiency impairs the formation of mitochondrial respiratory supercomplexes (RSCs) without altering the abundance of individual respiratory complex subunits. These impairments induced by PHB deficiency are effectively rescued by co-expression of PHB1 and PHB2, indicating that the multimeric PHB complex acts as the functional unit. Furthermore, downregulating other RSC assembly factors, including SCAFI (also known as COX7A2L), RCF1a (HIGD1A), RCF1b (HIGD2A), UQCC3 and SLP2 (STOML2), all activate mitoflashes through elevating mitochondrial ROS production. Our findings identify the PHB complex as a new regulator of RSC formation and mitoflash signaling, and delineate a general relationship among RSC formation, basal ROS production and mitoflash biogenesis. © 2017. Published by The Company of Biologists Ltd.

Screen for mitochondrial DNA copy number maintenance genes reveals essential role for ATP synthase

PubMed Central

Fukuoh, Atsushi; Cannino, Giuseppe; Gerards, Mike; Buckley, Suzanne; Kazancioglu, Selena; Scialo, Filippo; Lihavainen, Eero; Ribeiro, Andre; Dufour, Eric; Jacobs, Howard T

2014-01-01

The machinery of mitochondrial DNA (mtDNA) maintenance is only partially characterized and is of wide interest due to its involvement in disease. To identify novel components of this machinery, plus other cellular pathways required for mtDNA viability, we implemented a genome-wide RNAi screen in Drosophila S2 cells, assaying for loss of fluorescence of mtDNA nucleoids stained with the DNA-intercalating agent PicoGreen. In addition to previously characterized components of the mtDNA replication and transcription machineries, positives included many proteins of the cytosolic proteasome and ribosome (but not the mitoribosome), three proteins involved in vesicle transport, some other factors involved in mitochondrial biogenesis or nuclear gene expression, > 30 mainly uncharacterized proteins and most subunits of ATP synthase (but no other OXPHOS complex). ATP synthase knockdown precipitated a burst of mitochondrial ROS production, followed by copy number depletion involving increased mitochondrial turnover, not dependent on the canonical autophagy machinery. Our findings will inform future studies of the apparatus and regulation of mtDNA maintenance, and the role of mitochondrial bioenergetics and signaling in modulating mtDNA copy number. PMID:24952591

Transcription profiling suggests that mitochondrial topoisomerase IB acts as a topological barrier and regulator of mitochondrial DNA transcription.

PubMed

Dalla Rosa, Ilaria; Zhang, Hongliang; Khiati, Salim; Wu, Xiaolin; Pommier, Yves

2017-12-08

Mitochondrial DNA (mtDNA) is essential for cell viability because it encodes subunits of the respiratory chain complexes. Mitochondrial topoisomerase IB (TOP1MT) facilitates mtDNA replication by removing DNA topological tensions produced during mtDNA transcription, but it appears to be dispensable. To test whether cells lacking TOP1MT have aberrant mtDNA transcription, we performed mitochondrial transcriptome profiling. To that end, we designed and implemented a customized tiling array, which enabled genome-wide, strand-specific, and simultaneous detection of all mitochondrial transcripts. Our technique revealed that Top1mt KO mouse cells process the mitochondrial transcripts normally but that protein-coding mitochondrial transcripts are elevated. Moreover, we found discrete long noncoding RNAs produced by H-strand transcription and encompassing the noncoding regulatory region of mtDNA in human and murine cells and tissues. Of note, these noncoding RNAs were strongly up-regulated in the absence of TOP1MT. In contrast, 7S DNA, produced by mtDNA replication, was reduced in the Top1mt KO cells. We propose that the long noncoding RNA species in the D-loop region are generated by the extension of H-strand transcripts beyond their canonical stop site and that TOP1MT acts as a topological barrier and regulator for mtDNA transcription and D-loop formation.

DNA-PK Promotes the Mitochondrial, Metabolic, and Physical Decline that Occurs During Aging.

PubMed

Park, Sung-Jun; Gavrilova, Oksana; Brown, Alexandra L; Soto, Jamie E; Bremner, Shannon; Kim, Jeonghan; Xu, Xihui; Yang, Shutong; Um, Jee-Hyun; Koch, Lauren G; Britton, Steven L; Lieber, Richard L; Philp, Andrew; Baar, Keith; Kohama, Steven G; Abel, E Dale; Kim, Myung K; Chung, Jay H

2017-05-02

Hallmarks of aging that negatively impact health include weight gain and reduced physical fitness, which can increase insulin resistance and risk for many diseases, including type 2 diabetes. The underlying mechanism(s) for these phenomena is poorly understood. Here we report that aging increases DNA breaks and activates DNA-dependent protein kinase (DNA-PK) in skeletal muscle, which suppresses mitochondrial function, energy metabolism, and physical fitness. DNA-PK phosphorylates threonines 5 and 7 of HSP90α, decreasing its chaperone function for clients such as AMP-activated protein kinase (AMPK), which is critical for mitochondrial biogenesis and energy metabolism. Decreasing DNA-PK activity increases AMPK activity and prevents weight gain, decline of mitochondrial function, and decline of physical fitness in middle-aged mice and protects against type 2 diabetes. In conclusion, DNA-PK is one of the drivers of the metabolic and fitness decline during aging, and therefore DNA-PK inhibitors may have therapeutic potential in obesity and low exercise capacity. Published by Elsevier Inc.

PLK4 trans-Autoactivation Controls Centriole Biogenesis in Space.

PubMed

Lopes, Carla A M; Jana, Swadhin Chandra; Cunha-Ferreira, Inês; Zitouni, Sihem; Bento, Inês; Duarte, Paulo; Gilberto, Samuel; Freixo, Francisco; Guerrero, Adán; Francia, Maria; Lince-Faria, Mariana; Carneiro, Jorge; Bettencourt-Dias, Mónica

2015-10-26

Centrioles are essential for cilia and centrosome assembly. In centriole-containing cells, centrioles always form juxtaposed to pre-existing ones, motivating a century-old debate on centriole biogenesis control. Here, we show that trans-autoactivation of Polo-like kinase 4 (PLK4), the trigger of centriole biogenesis, is a critical event in the spatial control of that process. We demonstrate that centrioles promote PLK4 activation through its recruitment and local accumulation. Though centriole removal reduces the proportion of active PLK4, this is rescued by concentrating PLK4 to the peroxisome lumen. Moreover, while mild overexpression of PLK4 only triggers centriole amplification at the existing centriole, higher PLK4 levels trigger both centriolar and cytoplasmatic (de novo) biogenesis. Hence, centrioles promote their assembly locally and disfavor de novo synthesis. Similar mechanisms enforcing the local concentration and/or activity of other centriole components are likely to contribute to the spatial control of centriole biogenesis under physiological conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

The Mitochondrial Protein Import Component, TRANSLOCASE OF THE INNER MEMBRANE17-1, Plays a Role in Defining the Timing of Germination in Arabidopsis1[W][OPEN

PubMed Central

Wang, Yan; Law, Simon R.; Ivanova, Aneta; van Aken, Olivier; Kubiszewski-Jakubiak, Szymon; Uggalla, Vindya; van der Merwe, Margaretha; Duncan, Owen; Narsai, Reena; Whelan, James; Murcha, Monika W.

2014-01-01

In Arabidopsis (Arabidopsis thaliana), small gene families encode multiple isoforms for many of the components of the mitochondrial protein import apparatus. There are three isoforms of the TRANSLOCASE OF THE INNER MEMBRANE17 (Tim17). Transcriptome analysis indicates that AtTim17-1 is only detectable in dry seed. In this study, two independent transfer DNA insertional mutant lines of tim17-1 exhibited a germination-specific phenotype, showing a significant increase in the rate of germination. Microarray analyses revealed that Attim17-1 displayed alterations in the temporal sequence of transcriptomic events during germination, peaking earlier compared with the wild type. Promoter analysis of AtTim17-1 further identified an abscisic acid (ABA)-responsive element, which binds ABA-responsive transcription factors, acting to repress the expression of AtTim17-1. Attim17-1 dry seeds contained significantly increased levels of ABA and gibberellin, 2- and 5-fold, respectively. These results support the model that mitochondrial biogenesis is regulated in a tight temporal sequence of events during germination and that altering mitochondrial biogenesis feeds back to alter the germination rate, as evidenced by the altered levels of the master regulatory hormones that define germination. PMID:25253887

Molecular model of the mitochondrial genome segregation machinery in Trypanosoma brucei

PubMed Central

Hoffmann, Anneliese; Käser, Sandro; Jakob, Martin; Amodeo, Simona; Peitsch, Camille; Týč, Jiří; Vaughan, Sue; Schneider, André

2018-01-01

In almost all eukaryotes, mitochondria maintain their own genome. Despite the discovery more than 50 y ago, still very little is known about how the genome is correctly segregated during cell division. The protozoan parasite Trypanosoma brucei contains a single mitochondrion with a singular genome, the kinetoplast DNA (kDNA). Electron microscopy studies revealed the tripartite attachment complex (TAC) to physically connect the kDNA to the basal body of the flagellum and to ensure correct segregation of the mitochondrial genome via the basal bodies movement, during the cell cycle. Using superresolution microscopy, we precisely localize each of the currently known TAC components. We demonstrate that the TAC is assembled in a hierarchical order from the base of the flagellum toward the mitochondrial genome and that the assembly is not dependent on the kDNA itself. Based on the biochemical analysis, the TAC consists of several nonoverlapping subcomplexes, suggesting an overall size of the TAC exceeding 2.8 mDa. We furthermore demonstrate that the TAC is required for correct mitochondrial organelle positioning but not for organelle biogenesis or segregation. PMID:29434039

FGFR1 is essential for N-acetyl-seryl-aspartyl-lysyl-proline regulation of mitochondrial dynamics by upregulating microRNA let-7b-5p.

PubMed

Hu, Qiongying; Li, Jinpeng; Nitta, Kyoko; Kitada, Munehiro; Nagai, Takako; Kanasaki, Keizo; Koya, Daisuke

2018-01-15

Fibroblast growth factor receptor (FGFR) 1 plays a key role in endothelial homeostasis by inducing microRNA (miR) let-7. Our previous paper showed that anti-fibrotic effects of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) were associated with restoring diabetes-suppressed expression of FGFR1 and miR let-7, the key contributor of mitochondrial biogenesis, which is regulated by mitochondrial membrane GTPase proteins (MFN2 and OPA1). Here, we found that the FGFR1 signaling pathway was critical for AcSDKP in maintaining endothelial mitochondrial biogenesis through induction of miR let-7b-5p. In endothelial cells, AcSDKP restored the triple cytokines (TGF-β2, interleukin-1β, tumor necrosis factor-α)-suppressed miR let-7b-5p and protein levels of the mitochondrial membrane GTPase. This effect of AcSDKP was lost with either fibroblast growth factor receptor substrate 2 (FRS2) siRNA or neutralizing FGFR1-treated cells. Similarly, AcSDKP had no effect on the miR let-7b-5p inhibitor-suppressed GTPase levels in endothelial cells. In addition, a miR let-7b-5p mimic restored the levels of FRS2 siRNA-reduced GTPases in endothelial cells. These findings were also confirmed using MitoTracker Green and an immunofluorescence assay. Our results demonstrated that the AcSDKP-FGFR1 signaling pathway is critical for maintaining mitochondrial dynamics by control of miR let-7b-5p in endothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

RECG Maintains Plastid and Mitochondrial Genome Stability by Suppressing Extensive Recombination between Short Dispersed Repeats

PubMed Central

Odahara, Masaki; Masuda, Yuichi; Sato, Mayuko; Wakazaki, Mayumi; Harada, Chizuru; Toyooka, Kiminori; Sekine, Yasuhiko

2015-01-01

Maintenance of plastid and mitochondrial genome stability is crucial for photosynthesis and respiration, respectively. Recently, we have reported that RECA1 maintains mitochondrial genome stability by suppressing gross rearrangements induced by aberrant recombination between short dispersed repeats in the moss Physcomitrella patens. In this study, we studied a newly identified P. patens homolog of bacterial RecG helicase, RECG, some of which is localized in both plastid and mitochondrial nucleoids. RECG partially complements recG deficiency in Escherichia coli cells. A knockout (KO) mutation of RECG caused characteristic phenotypes including growth delay and developmental and mitochondrial defects, which are similar to those of the RECA1 KO mutant. The RECG KO cells showed heterogeneity in these phenotypes. Analyses of RECG KO plants showed that mitochondrial genome was destabilized due to a recombination between 8–79 bp repeats and the pattern of the recombination partly differed from that observed in the RECA1 KO mutants. The mitochondrial DNA (mtDNA) instability was greater in severe phenotypic RECG KO cells than that in mild phenotypic ones. This result suggests that mitochondrial genomic instability is responsible for the defective phenotypes of RECG KO plants. Some of the induced recombination caused efficient genomic rearrangements in RECG KO mitochondria. Such loci were sometimes associated with a decrease in the levels of normal mtDNA and significant decrease in the number of transcripts derived from the loci. In addition, the RECG KO mutation caused remarkable plastid abnormalities and induced recombination between short repeats (12–63 bp) in the plastid DNA. These results suggest that RECG plays a role in the maintenance of both plastid and mitochondrial genome stability by suppressing aberrant recombination between dispersed short repeats; this role is crucial for plastid and mitochondrial functions. PMID:25769081

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

Impaired TFEB-mediated Lysosome Biogenesis and Autophagy Promote Chronic Ethanol-induced Liver Injury and Steatosis in Mice.

PubMed

Chao, Xiaojuan; Wang, Shaogui; Zhao, Katrina; Li, Yuan; Williams, Jessica A; Li, Tiangang; Chavan, Hemantkumar; Krishnamurthy, Partha; He, Xi C; Li, Linheng; Ballabio, Andrea; Ni, Hong-Min; Ding, Wen-Xing

2018-05-18

Defects in lysosome function and autophagy contribute to pathogenesis of alcoholic liver disease. We investigated the mechanisms by which alcohol consumption affects these processes, evaluating the functions transcription factor EB (TFEB), which regulates lysosomal biogenesis. We performed studies with GFP-LC3 mice, mice with liver-specific deletion of transcription factor EB (TFEB), mice with disruption of the transcription factor E3 gene (TFE3-knockout mice), mice with disruption of the Tefb and Tfe3 genes (TFEB, TFE3 double-knockout mice), and Tfeb flox/flox albumin cre-negative mice (controls). TFEB was overexpressed from adenoviral vectors or knocked down with small interfering RNAs in mouse livers. Mice were placed on diets of chronic ethanol feeding plus an acute binge to induce liver damage (ethanol diet); some mice were also given injections of torin1, an inhibitor of the kinase activity of the mechanistic target of rapamycin (mTOR). Liver tissues were collected and analyzed by immunohistochemistry, immunoblots, and quantitative real-time PCR to monitor lysosome biogenesis. We analyzed levels of TFEB in liver tissues from patients with alcoholic hepatitis and from healthy donors (controls) by immunohistochemistry. Liver tissues from mice on the ethanol diet had lower levels of total and nuclear TFEB, compared with control mice, and hepatocytes had reduced lysosome biogenesis and autophagy. Hepatocytes from mice on the ethanol diet had increased translocation of mTOR into lysosomes, resulting increased mTOR activation. Administration of torin1 increased liver levels of TFEB and reduced steatosis and liver injury induced by ethanol. Mice that overexpressed TFEB in liver developed less-severe ethanol-induced liver injury and had increased lysosomal biogenesis and mitochondrial bioenergetics compared to mice carrying a control vector. Mice with knockdown of TFEB, as well as TFEB, TFE3 double-knockout mice, developed more severe liver injury in response to the

Effect of Roux-en-Y gastric bypass on liver mitochondrial dynamics in a rat model of obesity.

PubMed

Sacks, Jessica; Mulya, Anny; Fealy, Ciaran E; Huang, Hazel; Mosinski, John D; Pagadala, Mangesh R; Shimizu, Hideharu; Batayyah, Esam; Schauer, Philip R; Brethauer, Stacy A; Kirwan, John P

2018-02-01

Bariatric surgery provides significant and durable improvements in glycemic control and hepatic steatosis, but the underlying mechanisms that drive improvements in these metabolic parameters remain to be fully elucidated. Recently, alterations in mitochondrial morphology have shown a direct link to nutrient adaptations in obesity. Here, we evaluate the effects of Roux-en-Y gastric bypass (RYGB) surgery on markers of liver mitochondrial dynamics in a diet-induced obesity Sprague-Dawley (SD) rat model. Livers were harvested from adult male SD rats 90-days after either Sham or RYGB surgery and continuous high-fat feeding. We assessed expression of mitochondrial proteins involved in fusion, fission, mitochondrial autophagy (mitophagy) and biogenesis, as well as differences in citrate synthase activity and markers of oxidative stress. Gene expression for mitochondrial fusion genes, mitofusin 1 (Mfn1; P < 0.05), mitofusin 2 (Mfn2; P < 0.01), and optic atrophy 1 (OPA1; P < 0.05) increased following RYGB surgery. Biogenesis regulators, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α; P < 0.01) and nuclear respiratory factor 1 (Nrf1; P < 0.05), also increased in the RYGB group, as well as mitophagy marker, BCL-2 interacting protein 3 (Bnip3; P < 0.01). Protein expression for Mfn1 (P < 0.001), PGC1α (P < 0.05), BNIP3 (P < 0.0001), and mitochondrial complexes I-V (P < 0.01) was also increased by RYGB, and Mfn1 expression negatively correlated with body weight, insulin resistance, and fasting plasma insulin. In the RYGB group, citrate synthase activity was increased (P < 0.02) and reactive oxygen species (ROS) was decreased compared to the Sham control group (P < 0.05), although total antioxidant capacity was unchanged between groups. These data are the first to show an association between RYGB surgery and improved markers of liver mitochondrial dynamics. These observed improvements may be related to weight loss and reduced

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

Mitochondrial activity and dynamics changes regarding metabolism in ageing and obesity.

PubMed

López-Lluch, Guillermo

2017-03-01

Mitochondria play an essential role in ageing and longevity. During ageing, a general deregulation of metabolism occurs, affecting molecular, cellular and physiological activities in the organism. Dysfunction of mitochondria has been associated with ageing and age-related diseases indicating their importance in the maintenance of cell homeostasis. Three major nutritional sensors, mTOR, AMPK and Sirtuins are involved in the control of mitochondrial physiology. These nutritional sensors control mitochondrial biogenesis, dynamics by regulating fusion and fission processes, and turnover through mito- and autophagy. Apart of the known factors involved in fusion, OPA1 and mitofusins, and fission, DRP1 and FIS1, emerging factors such as prohibitins and sestrins can play important functions in mitochondrial dynamics regulation. Mitochondria is also affected by sexual hormones that suffer drastic changes during ageing. The recent literature demonstrates the complex interaction between nutritional sensors and mitochondrial homeostasis in the physiology of adipose tissue and in the accumulation of fat in other organs such as muscle and liver. In this article, the role of mitochondrial homeostasis in ageing and age-dependent fat accumulation is revised. This review highlights the importance of mitochondria in the accumulation of fat during ageing and related diseases such as obesity, metabolic syndrome or type 2 diabetes mellitus. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Metabolomics Reveals Signature of Mitochondrial Dysfunction in Diabetic Kidney Disease

PubMed Central

Karl, Bethany; Mathew, Anna V.; Gangoiti, Jon A.; Wassel, Christina L.; Saito, Rintaro; Pu, Minya; Sharma, Shoba; You, Young-Hyun; Wang, Lin; Diamond-Stanic, Maggie; Lindenmeyer, Maja T.; Forsblom, Carol; Wu, Wei; Ix, Joachim H.; Ideker, Trey; Kopp, Jeffrey B.; Nigam, Sanjay K.; Cohen, Clemens D.; Groop, Per-Henrik; Barshop, Bruce A.; Natarajan, Loki; Nyhan, William L.; Naviaux, Robert K.

2013-01-01

Diabetic kidney disease is the leading cause of ESRD, but few biomarkers of diabetic kidney disease are available. This study used gas chromatography-mass spectrometry to quantify 94 urine metabolites in screening and validation cohorts of patients with diabetes mellitus (DM) and CKD(DM+CKD), in patients with DM without CKD (DM–CKD), and in healthy controls. Compared with levels in healthy controls, 13 metabolites were significantly reduced in the DM+CKD cohorts (P≤0.001), and 12 of the 13 remained significant when compared with the DM–CKD cohort. Many of the differentially expressed metabolites were water-soluble organic anions. Notably, organic anion transporter-1 (OAT1) knockout mice expressed a similar pattern of reduced levels of urinary organic acids, and human kidney tissue from patients with diabetic nephropathy demonstrated lower gene expression of OAT1 and OAT3. Analysis of bioinformatics data indicated that 12 of the 13 differentially expressed metabolites are linked to mitochondrial metabolism and suggested global suppression of mitochondrial activity in diabetic kidney disease. Supporting this analysis, human diabetic kidney sections expressed less mitochondrial protein, urine exosomes from patients with diabetes and CKD had less mitochondrial DNA, and kidney tissues from patients with diabetic kidney disease had lower gene expression of PGC1α (a master regulator of mitochondrial biogenesis). We conclude that urine metabolomics is a reliable source for biomarkers of diabetic complications, and our data suggest that renal organic ion transport and mitochondrial function are dysregulated in diabetic kidney disease. PMID:23949796

Mitochondrial protein import: Mia40 facilitates Tim22 translocation into the inner membrane of mitochondria.

PubMed

Wrobel, Lidia; Trojanowska, Agata; Sztolsztener, Malgorzata E; Chacinska, Agnieszka

2013-03-01

The mitochondrial intermembrane space assembly (MIA) pathway is generally considered to be dedicated to the redox-dependent import and biogenesis of proteins localized to the intermembrane space of mitochondria. The oxidoreductase Mia40 is a central component of the pathway responsible for the transfer of disulfide bonds to intermembrane space precursor proteins, causing their oxidative folding. Here we present the first evidence that the function of Mia40 is not restricted to the transport and oxidative folding of intermembrane space proteins. We identify Tim22, a multispanning membrane protein and core component of the TIM22 translocase of inner membrane, as a protein with cysteine residues undergoing oxidation during Tim22 biogenesis. We show that Mia40 is involved in the biogenesis and complex assembly of Tim22. Tim22 forms a disulfide-bonded intermediate with Mia40 upon import into mitochondria. Of interest, Mia40 binds the Tim22 precursor also via noncovalent interactions. We propose that Mia40 not only is responsible for disulfide bond formation, but also assists the Tim22 protein in its integration into the inner membrane of mitochondria.

Mitochondrial markers predict recurrence, metastasis and tamoxifen-resistance in breast cancer patients: Early detection of treatment failure with companion diagnostics.

PubMed

Sotgia, Federica; Fiorillo, Marco; Lisanti, Michael P

2017-09-15

Here, we used a data-mining and informatics approach to discover new biomarkers of resistance to hormonal therapy in breast cancer. More specifically, we investigated whether nuclear-encoded genes associated with mitochondrial biogenesis can be used to predict tumor recurrence, distant metastasis and treatment failure in high-risk breast cancer patients. Overall, this strategy allowed us to directly provide in silico validation of the prognostic value of these mitochondrial components in large and clinically relevant patient populations, with >15 years of follow-up data. For this purpose, we employed a group of 145 ER(+) luminal A breast cancer patients, with lymph-node (LN) metastasis at diagnosis, that were treated with tamoxifen, but not any chemotherapy agents. Using this approach, we identified >60 new individual mitochondrial biomarkers that predicted treatment failure and tumor recurrence, with hazard-ratios (HR) of up to 4.17 ( p =2.2e-07). These include mitochondrial chaperones (HSPD1, HSPA9), membrane proteins (VDAC2, TOMM70A) and anti-oxidants (SOD2), as well as 18 different mitochondrial ribosomal proteins (MRPs) and >20 distinct components of the OXPHOS complexes. In addition, we combined 4 mitochondrial proteins (HSPD1, UQCRB, MRPL15, COX17), to generate a compact mitochondrial gene signature, associated with a HR of 5.34 ( p =1e-09). This signature also successfully predicted distant metastasis and was effective in larger groups of ER(+) ( N =2,447), basal ( N =540) and HER2(+) ( N =193) breast cancers. It was also effective in all breast cancers ( N =3,180), if considered together as a single group. Based on this analysis, we conclude that mitochondrial biogenesis should be considered as a new therapeutic target for overcoming tumor recurrence, distant metastasis and treatment failure in patients with breast cancer. In summary, we identified individual mitochondrial biomarkers and 2 compact mitochondrial gene signatures that can be used to predict

Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells

PubMed Central

Caballano-Infantes, Estefania; Terron-Bautista, José; Beltrán-Povea, Amparo; Cahuana, Gladys M; Soria, Bernat; Nabil, Hajji; Bedoya, Francisco J; Tejedo, Juan R

2017-01-01

Mitochondrial dysfunction and endoplasmic reticulum stress (ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide (NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca2+ flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstrated the need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies. PMID:28289506

Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells.

PubMed

Caballano-Infantes, Estefania; Terron-Bautista, José; Beltrán-Povea, Amparo; Cahuana, Gladys M; Soria, Bernat; Nabil, Hajji; Bedoya, Francisco J; Tejedo, Juan R

2017-02-26

Mitochondrial dysfunction and endoplasmic reticulum stress (ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide (NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca 2+ flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstrated the need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies.

Impaired parkin-mediated mitochondrial targeting to autophagosomes differentially contributes to tissue pathology in lysosomal storage diseases

PubMed Central

de Pablo-Latorre, Raquel; Saide, Assunta; Polishhuck, Elena V.; Nusco, Edoardo; Fraldi, Alessandro; Ballabio, Andrea

2012-01-01

Dysfunctional mitochondria are a well-known disease hallmark. The accumulation of aberrant mitochondria can alter cell homeostasis, thus resulting in tissue degeneration. Lysosomal storage disorders (LSDs) are a group of inherited diseases characterized by the buildup of undegraded material inside the lysosomes that leads to autophagic-lysosomal dysfunction. In LSDs, autophagic stress has been associated to mitochondrial accumulation and dysfunction. However, the mechanisms underlying mitochondrial aberrations and how these are involved in tissue pathogenesis remain largely unexplored. In normal conditions, mitochondrial clearance occurs by mitophagy, a selective form of autophagy, which relies on a parkin-mediated mitochondrial priming and subsequent sequestration by autophagosomes. Here, we performed a detailed analysis of key steps of mitophagy in a mouse model of multiple sulfatase deficiency (MSD), a severe type of LSD characterized by both neurological and systemic involvement. We demonstrated that in MSD liver reduced parkin levels resulted in inefficient mitochondrial priming, thus contributing to the accumulation of giant mitochondria that are located outside autophagic vesicles ultimately leading to cytochrome c release and apoptotic cell death. Morphological and functional changes were also observed in mitochondria from MSD brain but these were not directly associated with neuronal cell loss, suggesting a secondary contribution of mitochondria to neurodegeneration. Together, these data shed new light on the mechanisms underlying mitochondrial dysfunction in LSDs and on their tissue-specific differential contribution to the pathogenesis of this group of metabolic disorders. PMID:22215441

Role of AAA(+)-proteins in peroxisome biogenesis and function.

PubMed

Grimm, Immanuel; Erdmann, Ralf; Girzalsky, Wolfgang

2016-05-01

Mutations in the PEX1 gene, which encodes a protein required for peroxisome biogenesis, are the most common cause of the Zellweger spectrum diseases. The recognition that Pex1p shares a conserved ATP-binding domain with p97 and NSF led to the discovery of the extended family of AAA+-type ATPases. So far, four AAA+-type ATPases are related to peroxisome function. Pex6p functions together with Pex1p in peroxisome biogenesis, ATAD1/Msp1p plays a role in membrane protein targeting and a member of the Lon-family of proteases is associated with peroxisomal quality control. This review summarizes the current knowledge on the AAA+-proteins involved in peroxisome biogenesis and function.

Mitochondrial uncoupling reduces exercise capacity despite several skeletal muscle metabolic adaptations.

PubMed

Schlagowski, A I; Singh, F; Charles, A L; Gali Ramamoorthy, T; Favret, F; Piquard, F; Geny, B; Zoll, J

2014-02-15

The effects of mitochondrial uncoupling on skeletal muscle mitochondrial adaptation and maximal exercise capacity are unknown. In this study, rats were divided into a control group (CTL, n = 8) and a group treated with 2,4-dinitrophenol, a mitochondrial uncoupler, for 28 days (DNP, 30 mg·kg(-1)·day(-1) in drinking water, n = 8). The DNP group had a significantly lower body mass (P < 0.05) and a higher resting oxygen uptake (Vo2, P < 0.005). The incremental treadmill test showed that maximal running speed and running economy (P < 0.01) were impaired but that maximal Vo2 (Vo2max) was higher in the DNP-treated rats (P < 0.05). In skinned gastrocnemius fibers, basal respiration (V0) was higher (P < 0.01) in the DNP-treated animals, whereas the acceptor control ratio (ACR, Vmax/V0) was significantly lower (P < 0.05), indicating a reduction in OXPHOS efficiency. In skeletal muscle, DNP activated the mitochondrial biogenesis pathway, as indicated by changes in the mRNA expression of PGC1-α and -β, NRF-1 and -2, and TFAM, and increased the mRNA expression of cytochrome oxidase 1 (P < 0.01). The expression of two mitochondrial proteins (prohibitin and Ndufs 3) was higher after DNP treatment. Mitochondrial fission 1 protein (Fis-1) was increased in the DNP group (P < 0.01), but mitofusin-1 and -2 were unchanged. Histochemical staining for NADH dehydrogenase and succinate dehydrogenase activity in the gastrocnemius muscle revealed an increase in the proportion of oxidative fibers after DNP treatment. Our study shows that mitochondrial uncoupling induces several skeletal muscle adaptations, highlighting the role of mitochondrial coupling as a critical factor for maximal exercise capacities. These results emphasize the importance of investigating the qualitative aspects of mitochondrial function in addition to the amount of mitochondria.

Blood Cell Mitochondrial DNA Content and Premature Ovarian Aging

PubMed Central

Cacciatore, Chiara; Busnelli, Marta; Rossetti, Raffaella; Bonetti, Silvia; Paffoni, Alessio; Mari, Daniela; Ragni, Guido; Persani, Luca; Arosio, M.; Beck-Peccoz, P.; Biondi, M.; Bione, S.; Bruni, V.; Brigante, C.; Cannavo`, S.; Cavallo, L.; Cisternino, M.; Colombo, I.; Corbetta, S.; Crosignani, P.G.; D'Avanzo, M.G.; Dalpra, L.; Danesino, C.; Di Battista, E.; Di Prospero, F.; Donti, E.; Einaudi, S.; Falorni, A.; Foresta, C.; Fusi, F.; Garofalo, N.; Giotti, I.; Lanzi, R.; Larizza, D.; Locatelli, N.; Loli, P.; Madaschi, S.; Maghnie, M.; Maiore, S.; Mantero, F.; Marozzi, A.; Marzotti, S.; Migone, N.; Nappi, R.; Palli, D.; Patricelli, M.G.; Pisani, C.; Prontera, P.; Petraglia, F.; Radetti, G.; Renieri, A.; Ricca, I.; Ripamonti, A.; Rossetti, R.; Russo, G.; Russo, S.; Tonacchera, M.; Toniolo, D.; Torricelli, F.; Vegetti, W.; Villa, N.; Vineis, P.; Wasniewsk, M.; Zuffardi, O.

2012-01-01

Primary ovarian insufficiency (POI) is a critical fertility defect characterized by an anticipated and silent impairment of the follicular reserve, but its pathogenesis is largely unexplained. The frequent maternal inheritance of POI together with a remarkable dependence of ovarian folliculogenesis upon mitochondrial biogenesis and bioenergetics suggested the possible involvement of a generalized mitochondrial defect. Here, we verified the existence of a significant correlation between blood and ovarian mitochondrial DNA (mtDNA) content in a group of women undergoing ovarian hyperstimulation (OH), and then aimed to verify whether mtDNA content was significantly altered in the blood cells of POI women. We recruited 101 women with an impaired ovarian reserve: 59 women with premature ovarian failure (POF) and 42 poor responders (PR) to OH. A Taqman copy number assay revealed a significant mtDNA depletion (P<0.001) in both POF and PR women in comparison with 43 women of similar age and intact ovarian reserve, or 53 very old women with a previous physiological menopause. No pathogenic variations in the mitochondrial DNA polymerase γ (POLG) gene were detected in 57 POF or PR women with low blood mtDNA content. In conclusion, blood cell mtDNA depletion is a frequent finding among women with premature ovarian aging, suggesting that a still undetermined but generalized mitochondrial defect may frequently predispose to POI which could then be considered a form of anticipated aging in which the ovarian defect may represent the first manifestation. The determination of mtDNA content in blood may become an useful tool for the POI risk prediction. PMID:22879975

Blood cell mitochondrial DNA content and premature ovarian aging.

PubMed

Bonomi, Marco; Somigliana, Edgardo; Cacciatore, Chiara; Busnelli, Marta; Rossetti, Raffaella; Bonetti, Silvia; Paffoni, Alessio; Mari, Daniela; Ragni, Guido; Persani, Luca

2012-01-01

Primary ovarian insufficiency (POI) is a critical fertility defect characterized by an anticipated and silent impairment of the follicular reserve, but its pathogenesis is largely unexplained. The frequent maternal inheritance of POI together with a remarkable dependence of ovarian folliculogenesis upon mitochondrial biogenesis and bioenergetics suggested the possible involvement of a generalized mitochondrial defect. Here, we verified the existence of a significant correlation between blood and ovarian mitochondrial DNA (mtDNA) content in a group of women undergoing ovarian hyperstimulation (OH), and then aimed to verify whether mtDNA content was significantly altered in the blood cells of POI women. We recruited 101 women with an impaired ovarian reserve: 59 women with premature ovarian failure (POF) and 42 poor responders (PR) to OH. A Taqman copy number assay revealed a significant mtDNA depletion (P<0.001) in both POF and PR women in comparison with 43 women of similar age and intact ovarian reserve, or 53 very old women with a previous physiological menopause. No pathogenic variations in the mitochondrial DNA polymerase γ (POLG) gene were detected in 57 POF or PR women with low blood mtDNA content. In conclusion, blood cell mtDNA depletion is a frequent finding among women with premature ovarian aging, suggesting that a still undetermined but generalized mitochondrial defect may frequently predispose to POI which could then be considered a form of anticipated aging in which the ovarian defect may represent the first manifestation. The determination of mtDNA content in blood may become an useful tool for the POI risk prediction.

Early Mitochondrial Adaptations in Skeletal Muscle to Obesity and Obesity Resistance Differentially Regulated by High-Fat Diet.

PubMed

Sun, Jingyu; Huang, Tao; Qi, Zhengtang; You, Songhui; Dong, Jingmei; Zhang, Chen; Qin, Lili; Zhou, Yunhe; Ding, Shuzhe

2017-09-01

The mechanism for different susceptibilities to obesity after short-term high-fat diet (HFD) feeding is largely unknown. Given the close association between obesity occurrence and mitochondrial dysfunction, the early events in skeletal muscle mitochondrial adaptations between HFD-induced obesity (DIO) and HFD-induced obesity resistant (DIO-R) lean phenotype under excess nutritional environment were explored.ICR/JCL male mice were randomly divided into 2 groups, as follows: low-fat diet (LFD) and HFD groups. After 6 weeks on HFD, HFD-fed mice were classified as DIO or DIO-R according to their body weight gain. Serum parameters, oxidative stress biomarkers, the activation of AMPK/ACC axis, and the expression profiles of mitochondrial biogenesis were measured by using corresponding methods among the LFD control, DIO, and DIO-R groups. Serum glucose, total cholesterol, low-density lipoprotein, and high-density lipoprotein levels were significantly increased in DIO and DIO-R mice compared with LFD controls. However, DIO-R mice had significantly higher MDA levels and exhibited a significantly higher level of AMP-activated protein kinase (AMPK) activation and acetyl-CoA carboxylase (ACC) inactivation than DIO mice. Furthermore, the transcript and protein levels of transcriptional coactivator peroxisome proliferator-activated receptor γ (PPARγ) coactivator 1α (PGC-1α) and estrogen-related receptor-α (ERRα) in DIO-R mice were significantly up-regulated compared with the DIO mice. Although the body weight gain differed, the DIO and DIO-R mice had similar metabolic disturbance of glucose and lipids after short-term HFD consumption. The diverse alterations on fatty acid oxidation and mitochondrial biogenesis pathway induced by AMPK activation might be involved in different susceptibilities to obesity when consuming HFD. © Georg Thieme Verlag KG Stuttgart · New York.

Mitochondrial-nuclear genome interactions in non-alcoholic fatty liver disease in mice.

PubMed

Betancourt, Angela M; King, Adrienne L; Fetterman, Jessica L; Millender-Swain, Telisha; Finley, Rachel D; Oliva, Claudia R; Crowe, David R; Ballinger, Scott W; Bailey, Shannon M

2014-07-15

NAFLD (non-alcoholic fatty liver disease) involves significant changes in liver metabolism characterized by oxidative stress, lipid accumulation and fibrogenesis. Mitochondrial dysfunction and bioenergetic defects also contribute to NAFLD. In the present study, we examined whether differences in mtDNA influence NAFLD. To determine the role of mitochondrial and nuclear genomes in NAFLD, MNX (mitochondrial-nuclear exchange) 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 with 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 (respiratory control ratio) 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.

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

Estrogen-related receptor {alpha} is essential for the expression of antioxidant protection genes and mitochondrial function

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

Rangwala, Shamina M.; Li, Xiaoyan; Lindsley, Loren

2007-05-25

Estrogen-related receptor {alpha} (ERR{alpha}) is an important mediator of mitochondrial biogenesis and function. To investigate the transcriptional network controlling these phenomena, we investigated mitochondrial gene expression in embryonic fibroblasts isolated from ERR{alpha} null mice. Peroxisome proliferator-activated receptor {gamma} coactivator-1{alpha} (PGC-1{alpha}) stimulated mitochondrial gene expression program in control cells, but not in the ERR{alpha} null cells. Interestingly, the induction of levels of mitochondrial oxidative stress protection genes in response to increased PGC-1{alpha} levels was dependent on ERR{alpha}. Furthermore, we found that the PGC-1{alpha}-mediated induction of estrogen-related receptor {gamma} and nuclear respiratory factor 2 (NRF-2), was dependent on the presence of ERR{alpha}.more » Basal levels of NRF-2 were decreased in the absence of ERR{alpha}. The absence of ERR{alpha} resulted in a decrease in citrate synthase enzyme activity in response to PGC-1{alpha} overexpression. Our results indicate an essential role for ERR{alpha} as a key regulator of oxidative metabolism.« less

Mitochondrial energy deficiency leads to hyperproliferation of skeletal muscle mitochondria and enhanced insulin sensitivity.

PubMed

Morrow, Ryan M; Picard, Martin; Derbeneva, Olga; Leipzig, Jeremy; McManus, Meagan J; Gouspillou, Gilles; Barbat-Artigas, Sébastien; Dos Santos, Carlos; Hepple, Russell T; Murdock, Deborah G; Wallace, Douglas C

2017-03-07

Diabetes is associated with impaired glucose metabolism in the presence of excess insulin. Glucose and fatty acids provide reducing equivalents to mitochondria to generate energy, and studies have reported mitochondrial dysfunction in type II diabetes patients. If mitochondrial dysfunction can cause diabetes, then we hypothesized that increased mitochondrial metabolism should render animals resistant to diabetes. This was confirmed in mice in which the heart-muscle-brain adenine nucleotide translocator isoform 1 (ANT1) was inactivated. ANT1-deficient animals are insulin-hypersensitive, glucose-tolerant, and resistant to high fat diet (HFD)-induced toxicity. In ANT1-deficient skeletal muscle, mitochondrial gene expression is induced in association with the hyperproliferation of mitochondria. The ANT1-deficient muscle mitochondria produce excess reactive oxygen species (ROS) and are partially uncoupled. Hence, the muscle respiration under nonphosphorylating conditions is increased. Muscle transcriptome analysis revealed the induction of mitochondrial biogenesis, down-regulation of diabetes-related genes, and increased expression of the genes encoding the myokines FGF21 and GDF15. However, FGF21 was not elevated in serum, and FGF21 and UCP1 mRNAs were not induced in liver or brown adipose tissue (BAT). Hence, increased oxidation of dietary-reducing equivalents by elevated muscle mitochondrial respiration appears to be the mechanism by which ANT1-deficient mice prevent diabetes, demonstrating that the rate of mitochondrial oxidation of calories is important in the etiology of metabolic disease.

MitBASE : a comprehensive and integrated mitochondrial DNA database. The present status

PubMed Central

Attimonelli, M.; Altamura, N.; Benne, R.; Brennicke, A.; Cooper, J. M.; D’Elia, D.; Montalvo, A. de; Pinto, B. de; De Robertis, M.; Golik, P.; Knoop, V.; Lanave, C.; Lazowska, J.; Licciulli, F.; Malladi, B. S.; Memeo, F.; Monnerot, M.; Pasimeni, R.; Pilbout, S.; Schapira, A. H. V.; Sloof, P.; Saccone, C.

2000-01-01

MitBASE is an integrated and comprehensive database of mitochondrial DNA data which collects, under a single interface, databases for Plant, Vertebrate, Invertebrate, Human, Protist and Fungal mtDNA and a Pilot database on nuclear genes involved in mitochondrial biogenesis in Saccharomyces cerevisiae. MitBASE reports all available information from different organisms and from intraspecies variants and mutants. Data have been drawn from the primary databases and from the literature; value adding information has been structured, e.g., editing information on protist mtDNA genomes, pathological information for human mtDNA variants, etc. The different databases, some of which are structured using commercial packages (Microsoft Access, File Maker Pro) while others use a flat-file format, have been integrated under ORACLE. Ad hoc retrieval systems have been devised for some of the above listed databases keeping into account their peculiarities. The database is resident at the EBI and is available at the following site: http://www3.ebi.ac.uk/Research/Mitbase/mitbase.pl . The impact of this project is intended for both basic and applied research. The study of mitochondrial genetic diseases and mitochondrial DNA intraspecies diversity are key topics in several biotechnological fields. The database has been funded within the EU Biotechnology programme. PMID:10592207

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

Mitochonic Acid 5 (MA-5) Facilitates ATP Synthase Oligomerization and Cell Survival in Various Mitochondrial Diseases.

PubMed

Matsuhashi, Tetsuro; Sato, Takeya; Kanno, Shin-Ichiro; Suzuki, Takehiro; Matsuo, Akihiro; Oba, Yuki; Kikusato, Motoi; Ogasawara, Emi; Kudo, Tai; Suzuki, Kosuke; Ohara, Osamu; Shimbo, Hiroko; Nanto, Fumika; Yamaguchi, Hiroaki; Saigusa, Daisuke; Mukaiyama, Yasuno; Watabe, Akiko; Kikuchi, Koichi; Shima, Hisato; Mishima, Eikan; Akiyama, Yasutoshi; Oikawa, Yoshitsugu; Hsin-Jung, H O; Akiyama, Yukako; Suzuki, Chitose; Uematsu, Mitsugu; Ogata, Masaki; Kumagai, Naonori; Toyomizu, Masaaki; Hozawa, Atsushi; Mano, Nariyasu; Owada, Yuji; Aiba, Setsuya; Yanagisawa, Teruyuki; Tomioka, Yoshihisa; Kure, Shigeo; Ito, Sadayoshi; Nakada, Kazuto; Hayashi, Ken-Ichiro; Osaka, Hitoshi; Abe, Takaaki

2017-06-01

Mitochondrial dysfunction increases oxidative stress and depletes ATP in a variety of disorders. Several antioxidant therapies and drugs affecting mitochondrial biogenesis are undergoing investigation, although not all of them have demonstrated favorable effects in the clinic. We recently reported a therapeutic mitochondrial drug mitochonic acid MA-5 (Tohoku J. Exp. Med., 2015). MA-5 increased ATP, rescued mitochondrial disease fibroblasts and prolonged the life span of the disease model "Mitomouse" (JASN, 2016). To investigate the potential of MA-5 on various mitochondrial diseases, we collected 25 cases of fibroblasts from various genetic mutations and cell protective effect of MA-5 and the ATP producing mechanism was examined. 24 out of the 25 patient fibroblasts (96%) were responded to MA-5. Under oxidative stress condition, the GDF-15 was increased and this increase was significantly abrogated by MA-5. The serum GDF-15 elevated in Mitomouse was likewise reduced by MA-5. MA-5 facilitates mitochondrial ATP production and reduces ROS independent of ETC by facilitating ATP synthase oligomerization and supercomplex formation with mitofilin/Mic60. MA-5 reduced mitochondria fragmentation, restores crista shape and dynamics. MA-5 has potential as a drug for the treatment of various mitochondrial diseases. The diagnostic use of GDF-15 will be also useful in a forthcoming MA-5 clinical trial. Copyright © 2017 The Authors. Published by Elsevier B.V. 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

Dissecting tumor metabolic heterogeneity: Telomerase and large cell size metabolically define a sub-population of stem-like, mitochondrial-rich, cancer cells

PubMed Central

Lamb, Rebecca; Ozsvari, Bela; Bonuccelli, Gloria; Smith, Duncan L.; Pestell, Richard G.; Martinez-Outschoorn, Ubaldo E.; Clarke, Robert B.; Sotgia, Federica; Lisanti, Michael P.

2015-01-01

Tumor cell metabolic heterogeneity is thought to contribute to tumor recurrence, distant metastasis and chemo-resistance in cancer patients, driving poor clinical outcome. To better understand tumor metabolic heterogeneity, here we used the MCF7 breast cancer line as a model system to metabolically fractionate a cancer cell population. First, MCF7 cells were stably transfected with an hTERT-promoter construct driving GFP expression, as a surrogate marker of telomerase transcriptional activity. To enrich for immortal stem-like cancer cells, MCF7 cells expressing the highest levels of GFP (top 5%) were then isolated by FACS analysis. Notably, hTERT-GFP(+) MCF7 cells were significantly more efficient at forming mammospheres (i.e., stem cell activity) and showed increased mitochondrial mass and mitochondrial functional activity, all relative to hTERT-GFP(−) cells. Unbiased proteomics analysis of hTERT-GFP(+) MCF7 cells directly demonstrated the over-expression of 33 key mitochondrial proteins, 17 glycolytic enzymes, 34 ribosome-related proteins and 17 EMT markers, consistent with an anabolic cancer stem-like phenotype. Interestingly, MT-CO2 (cytochrome c oxidase subunit 2; Complex IV) expression was increased by >20-fold. As MT-CO2 is encoded by mt-DNA, this finding is indicative of increased mitochondrial biogenesis in hTERT-GFP(+) MCF7 cells. Importantly, most of these candidate biomarkers were transcriptionally over-expressed in human breast cancer epithelial cells in vivo. Similar results were obtained using cell size (forward/side scatter) to fractionate MCF7 cells. Larger stem-like cells also showed increased hTERT-GFP levels, as well as increased mitochondrial mass and function. Thus, this simple and rapid approach for the enrichment of immortal anabolic stem-like cancer cells will allow us and others to develop new prognostic biomarkers and novel anti-cancer therapies, by specifically and selectively targeting this metabolic sub-population of aggressive

Doxorubicin-induced mitophagy and mitochondrial damage is associated with dysregulation of the PINK1/parkin pathway.

PubMed

Yin, Jian; Guo, Jiabin; Zhang, Qiang; Cui, Lan; Zhang, Li; Zhang, Tingfen; Zhao, Jun; Li, Jin; Middleton, Alistair; Carmichael, Paul L; Peng, Shuangqing

2018-09-01

The usefulness of doxorubicin (DOX), a potent anticancer agent, is limited by its cardiotoxicity. Mitochondria play a central role in DOX-induced cardiotoxicity though the precise mechanisms are still obscure. Increasing evidence indicates that excessive activation of mitophagy and mitochondrial dysfunction are key causal events leading to DOX-induced cardiac injury. The PINK1/parkin pathway has emerged as a critical pathway in regulation of mitophagy as well as mitochondrial function. The present study was aimed to investigate the role of PINK1/parkin pathway in DOX-induced mitochondrial damage and cardiotoxicity. Our results showed that DOX concentration-dependently induced cytotoxicity and mitochondrial toxic effects including mitochondrial superoxide accumulation, decreased mitochondrial membrane potential and mitochondrial DNA copy number, as well as mitochondrial ultrastructural alterations. DOX induced mitophagy as evidenced by increases of the markers of autophagosomes, LC3, Beclin 1, reduction of p62, and co-localization of LC3 in mitochondria. DOX activated PINK1/parkin pathway and promoted translocation of PINK1/parkin to mitochondria. Meanwhile, DOX inhibited the expression of PGC-1α and its downstream targets nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM), and reduced the expression of mitochondrial proteins. Inhibition of mitophagy by mdivi-1 was found to attenuate activation of the PINK1/parkin pathway by DOX and preserve mitochondrial biogenesis, consequently mitigating DOX-induced mitochondrial superoxide overproduction and mitochondrial dysfunction. Moreover, scavenging mitochondrial superoxide by Mito-tempo was also found to effectively attenuate activation of the PINK1/parkin pathway and rescue the cells from DOX-induced adverse effects. Taken together, these findings suggest that DOX-induced mitophagy and mitochondrial damage in cardiomyocytes are mediated, at least in part, by dysregulation of the PINK1

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.

Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins.

PubMed

Aouacheria, Abdel; Baghdiguian, Stephen; Lamb, Heather M; Huska, Jason D; Pineda, Fernando J; Hardwick, J Marie

2017-10-01

The morphology of a population of mitochondria is the result of several interacting dynamical phenomena, including fission, fusion, movement, elimination and biogenesis. Each of these phenomena is controlled by underlying molecular machinery, and when defective can cause disease. New understanding of the relationships between form and function of mitochondria in health and disease is beginning to be unraveled on several fronts. Studies in mammals and model organisms have revealed that mitochondrial morphology, dynamics and function appear to be subject to regulation by the same proteins that regulate apoptotic cell death. One protein family that influences mitochondrial dynamics in both healthy and dying cells is the Bcl-2 protein family. Connecting mitochondrial dynamics with life-death pathway forks may arise from the intersection of Bcl-2 family proteins with the proteins and lipids that determine mitochondrial shape and function. Bcl-2 family proteins also have multifaceted influences on cells and mitochondria, including calcium handling, autophagy and energetics, as well as the subcellular localization of mitochondrial organelles to neuronal synapses. The remarkable range of physical or functional interactions by Bcl-2 family proteins is challenging to assimilate into a cohesive understanding. Most of their effects may be distinct from their direct roles in apoptotic cell death and are particularly apparent in the nervous system. Dual roles in mitochondrial dynamics and cell death extend beyond BCL-2 family proteins. In this review, we discuss many processes that govern mitochondrial structure and function in health and disease, and how Bcl-2 family proteins integrate into some of these processes. Copyright © 2017 Elsevier Ltd. 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.

Protection of scaffold protein Isu from degradation by the Lon protease Pim1 as a component of Fe-S cluster biogenesis regulation.

PubMed

Ciesielski, Szymon J; Schilke, Brenda; Marszalek, Jaroslaw; Craig, Elizabeth A

2016-04-01

Iron-sulfur (Fe-S) clusters, essential protein cofactors, are assembled on the mitochondrial scaffold protein Isu and then transferred to recipient proteins via a multistep process in which Isu interacts sequentially with multiple protein factors. This pathway is in part regulated posttranslationally by modulation of the degradation of Isu, whose abundance increases >10-fold upon perturbation of the biogenesis process. We tested a model in which direct interaction with protein partners protects Isu from degradation by the mitochondrial Lon-type protease. Using purified components, we demonstrated that Isu is indeed a substrate of the Lon-type protease and that it is protected from degradation by Nfs1, the sulfur donor for Fe-S cluster assembly, as well as by Jac1, the J-protein Hsp70 cochaperone that functions in cluster transfer from Isu. Nfs1 and Jac1 variants known to be defective in interaction with Isu were also defective in protecting Isu from degradation. Furthermore, overproduction of Jac1 protected Isu from degradation in vivo, as did Nfs1. Taken together, our results lead to a model of dynamic interplay between a protease and protein factors throughout the Fe-S cluster assembly and transfer process, leading to up-regulation of Isu levels under conditions when Fe-S cluster biogenesis does not meet cellular demands. © 2016 Ciesielski et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

α-MHC MitoTimer mouse: In vivo mitochondrial turnover model reveals remarkable mitochondrial heterogeneity in the heart

PubMed Central

Stotland, Aleksandr; Gottlieb, Roberta A.

2016-01-01

In order to maintain an efficient, energy-producing network in the heart, dysfunctional mitochondria are cleared through the mechanism of autophagy, which is closely linked with mitochondrial biogenesis; these, together with fusion and fission comprise a crucial process known as mitochondrial turnover. Until recently, the lack of molecular tools and methods available to researchers has impeded in vivo investigations of turnover. To investigate the process at the level of a single mitochondrion, our laboratory has developed the MitoTimer protein. Timer is a mutant of DsRed fluorescent protein characterized by transition from green fluorescence to a more stable red conformation over 48 h, and its rate of maturation is stable under physiological conditions. We fused the Timer cDNA with the inner mitochondrial membrane signal sequence and placed it under the control of a cardiac-restricted promoter. This construct was used to create the alpha-MHC-MitoTimer mice. Surprisingly, initial analysis of the hearts from these mice demonstrated a high degree of heterogeneity in the ratio of red-to-green fluorescence of MitoTimer in cardiac tissue. Further, scattered solitary mitochondria within cardiomyocytes display a much higher red-to-green fluorescence (red-shifted) relative to other mitochondria in the cell, implying a block in import of newly synthesized MitoTimer likely due to lower membrane potential. These red-shifted mitochondria may represent older, senescent mitochondria. Concurrently, the cardiomyocytes also contain a subpopulation of mitochondria that display a lower red-to-green fluorescence (green-shifted) relative to other mitochondria, indicative of germinal mitochondria that are actively engaged in import of newly-synthesized mito-targeted proteins. These mitochondria can be isolated and sorted from the heart by flow cytometry for further analysis. Initial studies suggest that these mice represent an elegant tool for the investigation of mitochondrial turnover

Minotaur is critical for primary piRNA biogenesis

PubMed Central

Vagin, Vasily V.; Yu, Yang; Jankowska, Anna; Luo, Yicheng; Wasik, Kaja A.; Malone, Colin D.; Harrison, Emily; Rosebrock, Adam; Wakimoto, Barbara T.; Fagegaltier, Delphine; Muerdter, Felix; Hannon, Gregory J.

2013-01-01

Piwi proteins and their associated small RNAs are essential for fertility in animals. In part, this is due to their roles in guarding germ cell genomes against the activity of mobile genetic elements. piRNA populations direct Piwi proteins to silence transposon targets and, as such, form a molecular code that discriminates transposons from endogenous genes. Information ultimately carried by piRNAs is encoded within genomic loci, termed piRNA clusters. These give rise to long, single-stranded, primary transcripts that are processed into piRNAs. Despite the biological importance of this pathway, neither the characteristics that define a locus as a source of piRNAs nor the mechanisms that catalyze primary piRNA biogenesis are well understood. We searched an EMS-mutant collection annotated for fertility phenotypes for genes involved in the piRNA pathway. Twenty-seven homozygous sterile strains showed transposon-silencing defects. One of these, which strongly impacted primary piRNA biogenesis, harbored a causal mutation in CG5508, a member of the Drosophila glycerol-3-phosphate O-acetyltransferase (GPAT) family. These enzymes catalyze the first acylation step on the path to the production of phosphatidic acid (PA). Though this pointed strongly to a function for phospholipid signaling in the piRNA pathway, a mutant form of CG5508, which lacks the GPAT active site, still functions in piRNA biogenesis. We have named this new biogenesis factor Minotaur. PMID:23788724

Measurement of Mitochondrial Cholesterol Import Using a Mitochondria-Targeted CYP11A1 Fusion Construct.

PubMed

Kennedy, Barry E; Charman, Mark; Karten, Barbara

2017-01-01

All animal membranes require cholesterol as an essential regulator of biophysical properties and function, but the levels of cholesterol vary widely among different subcellular compartments. Mitochondria, and in particular the inner mitochondrial membrane, have the lowest levels of cholesterol in the cell. Nevertheless, mitochondria need cholesterol for membrane maintenance and biogenesis, as well as oxysterol, steroid, and hepatic bile acid production. Alterations in mitochondrial cholesterol have been associated with a range of pathological conditions, including cancer, hepatosteatosis, cardiac ischemia, Alzheimer's, and Niemann-Pick Type C Disease. The mechanisms of mitochondrial cholesterol import are not fully elucidated yet, and may vary in different cell types and environmental conditions. Measuring cholesterol trafficking to the mitochondrial membranes is technically challenging because of its low abundance; for example, traditional pulse-chase experiments with isotope-labeled cholesterol are not feasible. Here, we describe improvements to a method first developed by the Miller group at the University of California to measure cholesterol trafficking to the inner mitochondrial membrane (IMM) through the conversion of cholesterol to pregnenolone. This method uses a mitochondria-targeted, ectopically expressed fusion construct of CYP11A1, ferredoxin reductase and ferredoxin. Pregnenolone is formed exclusively from cholesterol at the IMM, and can be analyzed with high sensitivity and specificity through ELISA or radioimmunoassay of the medium/buffer to reflect mitochondrial cholesterol import. This assay can be used to investigate the effects of genetic or pharmacological interventions on mitochondrial cholesterol import in cultured cells or isolated mitochondria.

The Circadian Clock Coordinates Ribosome Biogenesis

PubMed Central

Symul, Laura; Martin, Eva; Atger, Florian; Naef, Felix; Gachon, Frédéric

2013-01-01

Biological rhythms play a fundamental role in the physiology and behavior of most living organisms. Rhythmic circadian expression of clock-controlled genes is orchestrated by a molecular clock that relies on interconnected negative feedback loops of transcription regulators. Here we show that the circadian clock exerts its function also through the regulation of mRNA translation. Namely, the circadian clock influences the temporal translation of a subset of mRNAs involved in ribosome biogenesis by controlling the transcription of translation initiation factors as well as the clock-dependent rhythmic activation of signaling pathways involved in their regulation. Moreover, the circadian oscillator directly regulates the transcription of ribosomal protein mRNAs and ribosomal RNAs. Thus the circadian clock exerts a major role in coordinating transcription and translation steps underlying ribosome biogenesis. PMID:23300384

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

PubMed

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

2017-06-05

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

Human mesenchymal stromal cells transplanted into mice stimulate renal tubular cells and enhance mitochondrial function.

PubMed

Perico, Luca; Morigi, Marina; Rota, Cinzia; Breno, Matteo; Mele, Caterina; Noris, Marina; Introna, Martino; Capelli, Chiara; Longaretti, Lorena; Rottoli, Daniela; Conti, Sara; Corna, Daniela; Remuzzi, Giuseppe; Benigni, Ariela

2017-10-17

Mesenchymal stromal cells (MSCs) are renoprotective and drive regeneration following injury, although cellular targets of such an effect are still ill-defined. Here, we show that human umbilical cord (UC)-MSCs transplanted into mice stimulate tubular cells to regain mitochondrial mass and function, associated with enhanced microtubule-rich projections that appear to mediate mitochondrial trafficking to create a reparative dialogue among adjacent tubular cells. Treatment with UC-MSCs in mice with cisplatin-induced acute kidney injury (AKI) regulates mitochondrial biogenesis in proximal tubuli by enhancing PGC1α expression, NAD + biosynthesis and Sirtuin 3 (SIRT3) activity, thus fostering antioxidant defenses and ATP production. The functional role of SIRT3 in tubular recovery is highlighted by data that in SIRT3-deficient mice with AKI, UC-MSC treatment fails to induce renoprotection. These data document a previously unrecognized mechanism through which UC-MSCs facilitate renal repair, so as to induce global metabolic reprogramming of damaged tubular cells to sustain energy supply.Mesenchymal stromal cells drive renal regeneration following injury. Here, the authors show that human mesenchymal stromal cells, when transplanted into mice with acute kidney injury, stimulate renal tubular cell growth and enhance mitochondrial function via SIRT3.

Mitochondrial carrier protein biogenesis: role of the chaperones Hsc70 and Hsp90

PubMed Central

Zara, Vincenzo; Ferramosca, Alessandra; Robitaille-Foucher, Philippe; Palmieri, Ferdinando; Young, Jason C.

2016-01-01

Metabolite carrier proteins of the mitochondrial inner membrane share homology in their transmembrane domains, which also carries their targeting information. In addition, some carriers have cleavable presequences which are not essential for targeting, but have some other function before import. The cytosolic chaperones Hsc70 (heat-shock cognate 70) and Hsp90 (heat-shock protein 90) complex with carrier precursors and interact specifically with the Tom (translocase of the mitochondrial outer membrane) 70 import receptor to promote import. We analysed how the presequences of the PiC (phosphate carrier) and CIC (citrate carrier) relate to the mechanisms of chaperone-mediated import. Deletion of the PiC presequence reduced the efficiency of import but, notably, not by causing aggregation. Instead, binding of the protein to Hsc70 was reduced, as well as the dependence on Hsc70 for import. Hsp90 binding and function in import was not greatly affected, but it could not entirely compensate for the lack of Hsc70 interaction. Deletion of the presequence from CIC was shown to cause its aggregation, but had little effect on the contribution to import of either Hsc70 or Hsp90. The presequence of PiC, but not that of CIC, conferred Hsc70 binding to dihydrofolate reductase fusion proteins. In comparison, OGC (oxoglutarate carrier) lacks a presequence and was more soluble, though it is still dependent on both Hsc70 and Hsp90. We propose that carrier presequences evolved to improve targeting competence by different mechanisms, depending on physical properties of the precursors in the cytosolic targeting environment. PMID:19143589

Mitochondrial carrier protein biogenesis: role of the chaperones Hsc70 and Hsp90.

PubMed

Zara, Vincenzo; Ferramosca, Alessandra; Robitaille-Foucher, Philippe; Palmieri, Ferdinando; Young, Jason C

2009-04-15

Metabolite carrier proteins of the mitochondrial inner membrane share homology in their transmembrane domains, which also carries their targeting information. In addition, some carriers have cleavable presequences which are not essential for targeting, but have some other function before import. The cytosolic chaperones Hsc70 (heat-shock cognate 70) and Hsp90 (heat-shock protein 90) complex with carrier precursors and interact specifically with the Tom (translocase of the mitochondrial outer membrane) 70 import receptor to promote import. We analysed how the presequences of the PiC (phosphate carrier) and CIC (citrate carrier) relate to the mechanisms of chaperone-mediated import. Deletion of the PiC presequence reduced the efficiency of import but, notably, not by causing aggregation. Instead, binding of the protein to Hsc70 was reduced, as well as the dependence on Hsc70 for import. Hsp90 binding and function in import was not greatly affected, but it could not entirely compensate for the lack of Hsc70 interaction. Deletion of the presequence from CIC was shown to cause its aggregation, but had little effect on the contribution to import of either Hsc70 or Hsp90. The presequence of PiC, but not that of CIC, conferred Hsc70 binding to dihydrofolate reductase fusion proteins. In comparison, OGC (oxoglutarate carrier) lacks a presequence and was more soluble, though it is still dependent on both Hsc70 and Hsp90. We propose that carrier presequences evolved to improve targeting competence by different mechanisms, depending on physical properties of the precursors in the cytosolic targeting environment.

Tools for assessing mitochondrial dynamics in mouse tissues and neurodegenerative models

NASA Astrophysics Data System (ADS)

Pham, Anh H.

Mitochondria are dynamic organelles that undergo membrane fusion and fission and transport. The dynamic properties of mitochondria are important for regulating mitochondrial function. Defects in mitochondrial dynamics are linked neurodegenerative diseases and affect the development of many tissues. To investigate the role of mitochondrial dynamics in diseases, versatile tools are needed to explore the physiology of these dynamic organelles in multiple tissues. Current tools for monitoring mitochondrial dynamics have been limited to studies in cell culture, which may be inadequate model systems for exploring the network of tissues. Here, we have generated mouse models for monitoring mitochondrial dynamics in a broad spectrum of tissues and cell types. The Photo-Activatable Mitochondrial (PhAM floxed) line enables Cre-inducible expression of a mitochondrial targeted photoconvertible protein, Dendra2 (mito-Dendra2). In the PhAMexcised line, mito-Dendra2 is ubiquitously expressed to facilitate broad analysis of mitochondria at various developmental processes. We have utilized these models to study mitochondrial dynamics in the nigrostriatal circuit of Parkinson's disease (PD) and in the development of skeletal muscles. Increasing evidences implicate aberrant regulation of mitochondrial fusion and fission in models of PD. To assess the function of mitochondrial dynamics in the nigrostriatal circuit, we utilized transgenic techniques to abrogate mitochondrial fusion. We show that deletion of the Mfn2 leads to the degeneration of dopaminergic neurons and Parkinson's-like features in mice. To elucidate the dynamic properties of mitochondria during muscle development, we established a platform for examining mitochondrial compartmentalization in skeletal muscles. This model system may yield clues to the role of mitochondrial dynamics in mitochondrial myopathies.

Chlorogenic acid ameliorates endotoxin-induced liver injury by promoting mitochondrial oxidative phosphorylation

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

Zhou, Yan; College of Food Safety, Guizhou Medical University, Guiyang 550025; Ruan, Zheng, E-mail: ruanzheng@ncu.edu.cn

Acute or chronic hepatic injury is a common pathology worldwide. Mitochondrial dysfunction and the depletion of adenosine triphosphate (ATP) play important roles in liver injury. Chlorogenic acids (CGA) are some of the most abundant phenolic acids in human diet. This study was designed to test the hypothesis that CGA may protect against chronic lipopolysaccharide (LPS)-induced liver injury by modulating mitochondrial energy generation. CGA decreased the activities of serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase. The contents of ATP and adenosine monophosphate (AMP), as well as the ratio of AMP/ATP, were increased after CGA supplementation. The activities of enzymes thatmore » are involved in glycolysis were reduced, while those of enzymes involved in oxidative phosphorylation were increased. Moreover, phosphorylated AMP-activated protein kinase (AMPK), and mRNA levels of AMPK-α, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), nuclear respiratory factor 1, and mitochondrial DNA transcription factor A were increased after CGA supplementation. Collectively, these findings suggest that the hepatoprotective effect of CGA might be associated with enhanced ATP production, the stimulation of mitochondrial oxidative phosphorylation and the inhibition of glycolysis. - Highlights: • Dietary supplementation with chlorogenic acid (CGA) improved endotoxin-induced liver injury. • Chlorogenic acid enhances ATP increase and shifts energy metabolism, which is correlated with up-regulation AMPK and PGC-1α. • The possible mechanism of CGA on mitochondrial biogenesis was correlated with up-regulation AMPK and PGC-1α.« less

Sirtuin signaling controls mitochondrial function in glycogen storage disease type Ia.

PubMed

Cho, Jun-Ho; Kim, Goo-Young; Mansfield, Brian C; Chou, Janice Y

2018-05-08

Glycogen storage disease type Ia (GSD-Ia) deficient in glucose-6-phosphatase-α (G6Pase-α) is a metabolic disorder characterized by impaired glucose homeostasis and a long-term complication of hepatocellular adenoma/carcinoma (HCA/HCC). Mitochondrial dysfunction has been implicated in GSD-Ia but the underlying mechanism and its contribution to HCA/HCC development remain unclear. We have shown that hepatic G6Pase-α deficiency leads to downregulation of sirtuin 1 (SIRT1) signaling that underlies defective hepatic autophagy in GSD-Ia. SIRT1 is a NAD + -dependent deacetylase that can deacetylate and activate peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), a master regulator of mitochondrial integrity, biogenesis, and function. We hypothesized that downregulation of hepatic SIRT1 signaling in G6Pase-α-deficient livers impairs PGC-1α activity, leading to mitochondrial dysfunction. Here we show that the G6Pase-α-deficient livers display defective PGC-1α signaling, reduced numbers of functional mitochondria, and impaired oxidative phosphorylation. Overexpression of hepatic SIRT1 restores PGC-1α activity, normalizes the expression of electron transport chain components, and increases mitochondrial complex IV activity. We have previously shown that restoration of hepatic G6Pase-α expression normalized SIRT1 signaling. We now show that restoration of hepatic G6Pase-α expression also restores PGC-1α activity and mitochondrial function. Finally, we show that HCA/HCC lesions found in G6Pase-α-deficient livers contain marked mitochondrial and oxidative DNA damage. Taken together, our study shows that downregulation of hepatic SIRT1/PGC-1α signaling underlies mitochondrial dysfunction and that oxidative DNA damage incurred by damaged mitochondria may contribute to HCA/HCC development in GSD-Ia.

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

PubMed

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

2014-04-01

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

Newly identified protein Imi1 affects mitochondrial integrity and glutathione homeostasis in Saccharomyces cerevisiae.

PubMed

Kowalec, Piotr; Grynberg, Marcin; Pająk, Beata; Socha, Anna; Winiarska, Katarzyna; Fronk, Jan; Kurlandzka, Anna

2015-09-01

Glutathione homeostasis is crucial for cell functioning. We describe a novel Imi1 protein of Saccharomyces cerevisiae affecting mitochondrial integrity and involved in controlling glutathione level. Imi1 is cytoplasmic and, except for its N-terminal Flo11 domain, has a distinct solenoid structure. A lack of Imi1 leads to mitochondrial lesions comprising aberrant morphology of cristae and multifarious mtDNA rearrangements and impaired respiration. The mitochondrial malfunctioning is coupled to significantly decrease the level of intracellular reduced glutathione without affecting oxidized glutathione, which decreases the reduced/oxidized glutathione ratio. These defects are accompanied by decreased cadmium sensitivity and increased phytochelatin-2 level. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Immortalized Parkinson's disease lymphocytes have enhanced mitochondrial respiratory activity

PubMed Central

Annesley, Sarah J.; Lay, Sui T.; De Piazza, Shawn W.; Sanislav, Oana; Hammersley, Eleanor; Allan, Claire Y.; Francione, Lisa M.; Bui, Minh Q.; Chen, Zhi-Ping; Ngoei, Kevin R. W.; Tassone, Flora; Kemp, Bruce E.; Storey, Elsdon; Evans, Andrew; Loesch, Danuta Z.

2016-01-01

ABSTRACT In combination with studies of post-mortem Parkinson's disease (PD) brains, pharmacological and genetic models of PD have suggested that two fundamental interacting cellular processes are impaired – proteostasis and mitochondrial respiration. We have re-examined the role of mitochondrial dysfunction in lymphoblasts isolated from individuals with idiopathic PD and an age-matched control group. As previously reported for various PD cell types, the production of reactive oxygen species (ROS) by PD lymphoblasts was significantly elevated. However, this was not due to an impairment of mitochondrial respiration, as is often assumed. Instead, basal mitochondrial respiration and ATP synthesis are dramatically elevated in PD lymphoblasts. The mitochondrial mass, genome copy number and membrane potential were unaltered, but the expression of indicative respiratory complex proteins was also elevated. This explains the increased oxygen consumption rates by each of the respiratory complexes in experimentally uncoupled mitochondria of iPD cells. However, it was not attributable to increased activity of the stress- and energy-sensing protein kinase AMPK, a regulator of mitochondrial biogenesis and activity. The respiratory differences between iPD and control cells were sufficiently dramatic as to provide a potentially sensitive and reliable biomarker of the disease state, unaffected by disease duration (time since diagnosis) or clinical severity. Lymphoblasts from control and PD individuals thus occupy two distinct, quasi-stable steady states; a ‘normal’ and a ‘hyperactive’ state characterized by two different metabolic rates. The apparent stability of the ‘hyperactive’ state in patient-derived lymphoblasts in the face of patient ageing, ongoing disease and mounting disease severity suggests an early, permanent switch to an alternative metabolic steady state. With its associated, elevated ROS production, the ‘hyperactive’ state might not cause pathology

A Reevaluation of Rice Mitochondrial Evolution Based on the Complete Sequence of Male-Fertile and Male-Sterile Mitochondrial Genomes1[C][W][OA

PubMed Central

Bentolila, Stéphane; Stefanov, Stefan

2012-01-01

Plant mitochondrial genomes have features that distinguish them radically from their animal counterparts: a high rate of rearrangement, of uptake and loss of DNA sequences, and an extremely low point mutation rate. Perhaps the most unique structural feature of plant mitochondrial DNAs is the presence of large repeated sequences involved in intramolecular and intermolecular recombination. In addition, rare recombination events can occur across shorter repeats, creating rearrangements that result in aberrant phenotypes, including pollen abortion, which is known as cytoplasmic male sterility (CMS). Using next-generation sequencing, we pyrosequenced two rice (Oryza sativa) mitochondrial genomes that belong to the indica subspecies. One genome is normal, while the other carries the wild abortive-CMS. We find that numerous rearrangements in the rice mitochondrial genome occur even between close cytotypes during rice evolution. Unlike maize (Zea mays), a closely related species also belonging to the grass family, integration of plastid sequences did not play a role in the sequence divergence between rice cytotypes. This study also uncovered an excellent candidate for the wild abortive-CMS-encoding gene; like most of the CMS-associated open reading frames that are known in other species, this candidate was created via a rearrangement, is chimeric in structure, possesses predicted transmembrane domains, and coopted the promoter of a genuine mitochondrial gene. Our data give new insights into rice mitochondrial evolution, correcting previous reports. PMID:22128137

A practice-changing culture method relying on shaking substantially increases mitochondrial energy metabolism and functionality of human liver cell lines.

PubMed

Adam, Aziza A A; van der Mark, Vincent A; Donkers, Joanne M; Wildenberg, Manon E; Oude Elferink, Ronald P J; Chamuleau, Robert A F M; Hoekstra, Ruurdtje