Importance of mitochondrial calcium uniporter in high glucose-induced endothelial cell dysfunction.

PubMed

Chen, Wei; Yang, Jie; Chen, Shuhua; Xiang, Hong; Liu, Hengdao; Lin, Dan; Zhao, Shaoli; Peng, Hui; Chen, Pan; Chen, Alex F; Lu, Hongwei

2017-11-01

Mitochondrial Ca 2+ overload is implicated in hyperglycaemia-induced endothelial cell dysfunction, but the key molecular events responsible remain unclear. We examined the involvement of mitochondrial calcium uniporter, which mediates mitochondrial Ca 2+ uptake, in endothelial cell dysfunction resulting from high-glucose treatment. Human umbilical vein endothelial cells were exposed to various glucose concentrations and to high glucose (30 mM) following mitochondrial calcium uniporter inhibition or activation with ruthenium red and spermine, respectively. Subsequently, mitochondrial calcium uniporter and mitochondrial calcium uniporter regulator 1 messenger RNA and protein expression was measured by real-time polymerase chain reaction and western blotting. Ca 2+ concentrations were analysed by laser confocal microscopy, and cytoplasmic and mitochondrial oxidative stress was detected using 2',7'-dichlorofluorescein diacetate and MitoSOX Red, respectively. Apoptosis was assessed by annexin V-fluorescein isothiocyanate/propidium iodide staining, and a wound-healing assay was performed using an in vitro model. High glucose markedly upregulated mitochondrial calcium uniporter and mitochondrial calcium uniporter regulator 1 messenger RNA expression, as well as protein production, in a dose- and time-dependent manner with a maximum effect demonstrated at 72 h and 30 mM glucose concentration. Moreover, high-glucose treatment significantly raised both mitochondrial and cytoplasmic Ca 2+ and reactive oxygen species levels, increased apoptosis and compromised wound healing (all p < 0.05). These effects were enhanced by spermine and completely negated by ruthenium red, which are known to activate and inhibit mitochondrial calcium uniporter, respectively. Mitochondrial calcium uniporter plays an important role in hyperglycaemia-induced endothelial cell dysfunction and may constitute a therapeutic target to reduce vascular complications in diabetes.

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

PubMed Central

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

2012-01-01

Background The identification of early mechanisms underlying Alzheimer's Disease (AD) and associated biomarkers could advance development of new therapies and improve monitoring and predicting of AD progression. Mitochondrial dysfunction has been suggested to underlie AD pathophysiology, however, no comprehensive study exists that evaluates the effect of different familial AD (FAD) mutations on mitochondrial function, dynamics, and brain energetics. Methods and Findings We characterized early mitochondrial dysfunction and metabolomic signatures of energetic stress in three commonly used transgenic mouse models of FAD. Assessment of mitochondrial motility, distribution, dynamics, morphology, and metabolomic profiling revealed the specific effect of each FAD mutation on the development of mitochondrial stress and dysfunction. Inhibition of mitochondrial trafficking was characteristic for embryonic neurons from mice expressing mutant human presenilin 1, PS1(M146L) and the double mutation of human amyloid precursor protein APP(Tg2576) and PS1(M146L) contributing to the increased susceptibility of neurons to excitotoxic cell death. Significant changes in mitochondrial morphology were detected in APP and APP/PS1 mice. All three FAD models demonstrated a loss of the integrity of synaptic mitochondria and energy production. Metabolomic profiling revealed mutation-specific changes in the levels of metabolites reflecting altered energy metabolism and mitochondrial dysfunction in brains of FAD mice. Metabolic biomarkers adequately reflected gender differences similar to that reported for AD patients and correlated well with the biomarkers currently used for diagnosis in humans. Conclusions Mutation-specific alterations in mitochondrial dynamics, morphology and function in FAD mice occurred prior to the onset of memory and neurological phenotype and before the formation of amyloid deposits. Metabolomic signatures of mitochondrial stress and altered energy metabolism indicated alterations in nucleotide, Krebs cycle, energy transfer, carbohydrate, neurotransmitter, and amino acid metabolic pathways. Mitochondrial dysfunction, therefore, is an underlying event in AD progression, and FAD mouse models provide valuable tools to study early molecular mechanisms implicated in AD. PMID:22393443

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

[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.

Effects of vildagliptin versus sitagliptin, on cardiac function, heart rate variability and mitochondrial function in obese insulin-resistant rats

PubMed Central

Apaijai, Nattayaporn; Pintana, Hiranya; Chattipakorn, Siriporn C; Chattipakorn, Nipon

2013-01-01

Background and Purpose Long-term high-fat diet (HFD) consumption has been shown to cause insulin resistance, which is characterized by hyperinsulinaemia with metabolic inflexibility. Insulin resistance is associated with cardiac sympathovagal imbalance, cardiac dysfunction and cardiac mitochondrial dysfunction. Dipeptidyl peptidase-4 (DPP-4) inhibitors, vildagliptin and sitagliptin, are oral anti-diabetic drugs often prescribed in patients with cardiovascular disease. Therefore, in this study, we sought to determine the effects of vildagliptin and sitagliptin in a murine model of insulin resistance. Experimental Approach Male Wistar rats weighing 180–200 g, were fed either a normal diet (20% energy from fat) or a HFD (59% energy from fat) for 12 weeks. These rats were then divided into three subgroups to receive vildagliptin (3 mg·kg−1·day−1), sitagliptin (30 mg·kg−1·day−1) or vehicle for another 21 days. Metabolic parameters, oxidative stress, heart rate variability (HRV), cardiac function and cardiac mitochondrial function were determined. Key Results Rats that received HFD developed insulin resistance characterized by increased body weight, plasma insulin, total cholesterol and oxidative stress levels along with a decreased high-density lipoprotein (HDL) level. Moreover, cardiac dysfunction, depressed HRV, cardiac mitochondrial dysfunction and cardiac mitochondrial morphology changes were observed in HFD rats. Both vildagliptin and sitagliptin decreased plasma insulin, total cholesterol and oxidative stress as well as increased HDL level. Furthermore, vildagliptin and sitagliptin attenuated cardiac dysfunction, prevented cardiac mitochondrial dysfunction and completely restored HRV. Conclusions and Implications Both vildagliptin and sitagliptin share similar efficacy in cardioprotection in obese insulin-resistant rats. PMID:23488656

A single cell high content assay detects mitochondrial dysfunction in iPSC-derived neurons with mutations in SNCA.

PubMed

Little, Daniel; Luft, Christin; Mosaku, Olukunbi; Lorvellec, Maëlle; Yao, Zhi; Paillusson, Sébastien; Kriston-Vizi, Janos; Gandhi, Sonia; Abramov, Andrey Y; Ketteler, Robin; Devine, Michael J; Gissen, Paul

2018-06-13

Mitochondrial dysfunction is implicated in many neurodegenerative diseases including Parkinson's disease (PD). Induced pluripotent stem cells (iPSCs) provide a unique cell model for studying neurological diseases. We have established a high-content assay that can simultaneously measure mitochondrial function, morphology and cell viability in iPSC-derived dopaminergic neurons. iPSCs from PD patients with mutations in SNCA and unaffected controls were differentiated into dopaminergic neurons, seeded in 384-well plates and stained with the mitochondrial membrane potential dependent dye TMRM, alongside Hoechst-33342 and Calcein-AM. Images were acquired using an automated confocal screening microscope and single cells were analysed using automated image analysis software. PD neurons displayed reduced mitochondrial membrane potential and altered mitochondrial morphology compared to control neurons. This assay demonstrates that high content screening techniques can be applied to the analysis of mitochondria in iPSC-derived neurons. This technique could form part of a drug discovery platform to test potential new therapeutics for PD and other neurodegenerative diseases.

Increased sensitivity to mitochondrial permeability transition and myonuclear translocation of endonuclease G in atrophied muscle of physically active older humans.

PubMed

Gouspillou, Gilles; Sgarioto, Nicolas; Kapchinsky, Sophia; Purves-Smith, Fennigje; Norris, Brandon; Pion, Charlotte H; Barbat-Artigas, Sébastien; Lemieux, Francois; Taivassalo, Tanja; Morais, José A; Aubertin-Leheudre, Mylène; Hepple, Russell T

2014-04-01

Mitochondrial dysfunction is implicated in skeletal muscle atrophy and dysfunction with aging, with strong support for an increased mitochondrial-mediated apoptosis in sedentary rodent models. Whether this applies to aged human muscle is unknown, nor is it clear whether these changes are caused by sedentary behavior. Thus, we examined mitochondrial function [respiration, reactive oxygen species (ROS) emission, and calcium retention capacity (CRC)] in permeabilized myofibers obtained from vastus lateralis muscle biopsies of healthy physically active young (23.7±2.7 yr; mean±SD) and older (71.2±4.9 yr) men. Although mitochondrial ROS and maximal respiratory capacity were unaffected, the acceptor control ratio was reduced by 18% with aging, suggesting mild uncoupling of oxidative phosphorylation. CRC was reduced by 50% with aging, indicating sensitization of the mitochondrial permeability transition pore (mPTP) to apoptosis. Consistent with the mPTP sensitization, older muscles showed a 3-fold greater fraction of endonuclease G (a mitochondrial proapoptotic factor)-positive myonuclei. Aged muscles also had lower mitophagic potential, based on a 43% reduction in Parkin to the voltage-dependent anion channel (VDAC) protein ratio. Collectively, these results show that mitochondrial-mediated apoptotic signaling is increased in older human muscle and suggest that accumulation of dysfunctional mitochondria with exaggerated apoptotic sensitivity is due to impaired mitophagy.

Malnutrition-associated liver steatosis and ATP depletion is caused by peroxisomal and mitochondrial dysfunction.

PubMed

van Zutphen, Tim; Ciapaite, Jolita; Bloks, Vincent W; Ackereley, Cameron; Gerding, Albert; Jurdzinski, Angelika; de Moraes, Roberta Allgayer; Zhang, Ling; Wolters, Justina C; Bischoff, Rainer; Wanders, Ronald J; Houten, Sander M; Bronte-Tinkew, Dana; Shatseva, Tatiana; Lewis, Gary F; Groen, Albert K; Reijngoud, Dirk-Jan; Bakker, Barbara M; Jonker, Johan W; Kim, Peter K; Bandsma, Robert H J

2016-12-01

Severe malnutrition in young children is associated with signs of hepatic dysfunction such as steatosis and hypoalbuminemia, but its etiology is unknown. Peroxisomes and mitochondria play key roles in various hepatic metabolic functions including lipid metabolism and energy production. To investigate the involvement of these organelles in the mechanisms underlying malnutrition-induced hepatic dysfunction we developed a rat model of malnutrition. Weanling rats were placed on a low protein or control diet (5% or 20% of calories from protein, respectively) for four weeks. Peroxisomal and mitochondrial structural features were characterized using immunofluorescence and electron microscopy. Mitochondrial function was assessed using high-resolution respirometry. A novel targeted quantitative proteomics method was applied to analyze 47 mitochondrial proteins involved in oxidative phosphorylation, tricarboxylic acid cycle and fatty acid β-oxidation pathways. Low protein diet-fed rats developed hypoalbuminemia and hepatic steatosis, consistent with the human phenotype. Hepatic peroxisome content was decreased and metabolomic analysis indicated peroxisomal dysfunction. This was followed by changes in mitochondrial ultrastructure and increased mitochondrial content. Mitochondrial function was impaired due to multiple defects affecting respiratory chain complex I and IV, pyruvate uptake and several β-oxidation enzymes, leading to strongly reduced hepatic ATP levels. Fenofibrate supplementation restored hepatic peroxisome abundance and increased mitochondrial β-oxidation capacity, resulting in reduced steatosis and normalization of ATP and plasma albumin levels. Malnutrition leads to severe impairments in hepatic peroxisomal and mitochondrial function, and hepatic metabolic dysfunction. We discuss the potential future implications of our findings for the clinical management of malnourished children. Severe malnutrition in children is associated with metabolic disturbances that are poorly understood. In order to study this further, we developed a malnutrition animal model and found that severe malnutrition leads to an impaired function of liver mitochondria which are essential for energy production and a loss of peroxisomes, which are important for normal liver metabolic function. Copyright © 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

A review of research trends in physiological abnormalities in autism spectrum disorders: immune dysregulation, inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures

PubMed Central

Rossignol, D A; Frye, R E

2012-01-01

Recent studies have implicated physiological and metabolic abnormalities in autism spectrum disorders (ASD) and other psychiatric disorders, particularly immune dysregulation or inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures (‘four major areas'). The aim of this study was to determine trends in the literature on these topics with respect to ASD. A comprehensive literature search from 1971 to 2010 was performed in these four major areas in ASD with three objectives. First, publications were divided by several criteria, including whether or not they implicated an association between the physiological abnormality and ASD. A large percentage of publications implicated an association between ASD and immune dysregulation/inflammation (416 out of 437 publications, 95%), oxidative stress (all 115), mitochondrial dysfunction (145 of 153, 95%) and toxicant exposures (170 of 190, 89%). Second, the strength of evidence for publications in each area was computed using a validated scale. The strongest evidence was for immune dysregulation/inflammation and oxidative stress, followed by toxicant exposures and mitochondrial dysfunction. In all areas, at least 45% of the publications were rated as providing strong evidence for an association between the physiological abnormalities and ASD. Third, the time trends in the four major areas were compared with trends in neuroimaging, neuropathology, theory of mind and genetics (‘four comparison areas'). The number of publications per 5-year block in all eight areas was calculated in order to identify significant changes in trends. Prior to 1986, only 12 publications were identified in the four major areas and 51 in the four comparison areas (42 for genetics). For each 5-year period, the total number of publications in the eight combined areas increased progressively. Most publications (552 of 895, 62%) in the four major areas were published in the last 5 years (2006–2010). Evaluation of trends between the four major areas and the four comparison areas demonstrated that the largest relative growth was in immune dysregulation/inflammation, oxidative stress, toxicant exposures, genetics and neuroimaging. Research on mitochondrial dysfunction started growing in the last 5 years. Theory of mind and neuropathology research has declined in recent years. Although most publications implicated an association between the four major areas and ASD, publication bias may have led to an overestimation of this association. Further research into these physiological areas may provide insight into general or subset-specific processes that could contribute to the development of ASD and other psychiatric disorders. PMID:22143005

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

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

PubMed Central

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

2010-01-01

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

Glucose Modulates Respiratory Complex I Activity in Response to Acute Mitochondrial Dysfunction

PubMed Central

Cannino, Giuseppe; El-Khoury, Riyad; Pirinen, Marja; Hutz, Bettina; Rustin, Pierre; Jacobs, Howard T.; Dufour, Eric

2012-01-01

Proper coordination between glycolysis and respiration is essential, yet the regulatory mechanisms involved in sensing respiratory chain defects and modifying mitochondrial functions accordingly are unclear. To investigate the nature of this regulation, we introduced respiratory bypass enzymes into cultured human (HEK293T) cells and studied mitochondrial responses to respiratory chain inhibition. In the absence of respiratory chain inhibitors, the expression of alternative respiratory enzymes did not detectably alter cell physiology or mitochondrial function. However, in permeabilized cells NDI1 (alternative NADH dehydrogenase) bypassed complex I inhibition, whereas alternative oxidase (AOX) bypassed complex III or IV inhibition. In contrast, in intact cells the effects of the AOX bypass were suppressed by growth on glucose, whereas those produced by NDI1 were unaffected. Moreover, NDI1 abolished the glucose suppression of AOX-driven respiration, implicating complex I as the target of this regulation. Rapid Complex I down-regulation was partly released upon prolonged respiratory inhibition, suggesting that it provides an “emergency shutdown” system to regulate metabolism in response to dysfunctions of the oxidative phosphorylation. This system was independent of HIF1, mitochondrial superoxide, or ATP synthase regulation. Our findings reveal a novel pathway for adaptation to mitochondrial dysfunction and could provide new opportunities for combatting diseases. PMID:23007390

Yeast mitochondria: an overview of mitochondrial biology and the potential of mitochondrial systems biology.

PubMed

Malina, Carl; Larsson, Christer; Nielsen, Jens

2018-08-01

Mitochondria are dynamic organelles of endosymbiotic origin that are essential components of eukaryal cells. They contain their own genetic machinery, have multicopy genomes and like their bacterial ancestors they consist of two membranes. However, the majority of the ancestral genome has been lost or transferred to the nuclear genome of the host, preserving only a core set of genes involved in oxidative phosphorylation. Mitochondria perform numerous biological tasks ranging from bioenergetics to production of protein co-factors, including heme and iron-sulfur clusters. Due to the importance of mitochondria in many cellular processes, mitochondrial dysfunction is implicated in a wide variety of human disorders. Much of our current knowledge on mitochondrial function and dysfunction comes from studies using Saccharomyces cerevisiae. This yeast has good fermenting capacity, rendering tolerance to mutations that inactivate oxidative phosphorylation and complete loss of mitochondrial DNA. Here, we review yeast mitochondrial metabolism and function with focus on S. cerevisiae and its contribution in understanding mitochondrial biology. We further review how systems biology studies, including mathematical modeling, has allowed gaining new insight into mitochondrial function, and argue that this approach may enable us to gain a holistic view on how mitochondrial function interacts with different cellular processes.

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

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

PubMed

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

2010-05-01

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

Mitochondrial reactive oxygen species generation triggers inflammatory response and tissue injury associated with hepatic ischemia-reperfusion: therapeutic potential of mitochondrially-targeted antioxidants

PubMed Central

Mukhopadhyay, Partha; Horváth, Bėla; Zsengellėr, Zsuzsanna; Bátkai, Sándor; Cao, Zongxian; Kechrid, Malek; Holovac, Eileen; Erdėlyi, Katalin; Tanchian, Galin; Liaudet, Lucas; Stillman, Isaac E.; Joseph, Joy; Kalyanaraman, Balaraman; Pacher, Pál

2012-01-01

Mitochondrial reactive oxygen species generation has been implicated in the pathophysiology of ischemia-reperfusion (I/R) injury, however its exact role and its spatial-temporal relationship with inflammation are elusive. Herein we explored the spatial-temporal relationship of oxidative/nitrative stress and inflammatory response during the course of hepatic I/R and the possible therapeutic potential of mitochondrial-targeted antioxidants, using a mouse model of segmental hepatic ischemia-reperfusion injury. Hepatic I/R was characterized by early (at 2 hours of reperfusion) mitochondrial injury, decreased complex I activity, increased oxidant generation in the liver or liver mitochondria, and profound hepatocellular injury/dysfunction with acute pro-inflammatory response (TNF-α, MIP-1αCCL3, MIP-2/CXCL2) without inflammatory cell infiltration, followed by marked neutrophil infiltration and more pronounced secondary wave of oxidative/nitrative stress in the liver (starting from 6 hours of reperfusion and peaking at 24 hours). Mitochondrially-targeted antioxidants, MitoQ or Mito-CP, dose-dependently attenuated I/R-induced liver dysfunction, the early and delayed oxidative and nitrative stress response (HNE/carbonyl adducts, malondialdehyde, 8-OHdG, and 3-nitrotyrosine formation), mitochondrial and histopathological injury/dysfunction, as well as delayed inflammatory cell infiltration and cell death. Mitochondrially generated oxidants play a central role in triggering the deleterious cascade of events associated with hepatic I/R, which may be targeted by novel antioxidants for therapeutic advantage. PMID:22683818

Cockayne syndrome group A and B proteins converge on transcription-linked resolution of non-B DNA.

PubMed

Scheibye-Knudsen, Morten; Tseng, Anne; Borch Jensen, Martin; Scheibye-Alsing, Karsten; Fang, Evandro Fei; Iyama, Teruaki; Bharti, Sanjay Kumar; Marosi, Krisztina; Froetscher, Lynn; Kassahun, Henok; Eckley, David Mark; Maul, Robert W; Bastian, Paul; De, Supriyo; Ghosh, Soumita; Nilsen, Hilde; Goldberg, Ilya G; Mattson, Mark P; Wilson, David M; Brosh, Robert M; Gorospe, Myriam; Bohr, Vilhelm A

2016-11-01

Cockayne syndrome is a neurodegenerative accelerated aging disorder caused by mutations in the CSA or CSB genes. Although the pathogenesis of Cockayne syndrome has remained elusive, recent work implicates mitochondrial dysfunction in the disease progression. Here, we present evidence that loss of CSA or CSB in a neuroblastoma cell line converges on mitochondrial dysfunction caused by defects in ribosomal DNA transcription and activation of the DNA damage sensor poly-ADP ribose polymerase 1 (PARP1). Indeed, inhibition of ribosomal DNA transcription leads to mitochondrial dysfunction in a number of cell lines. Furthermore, machine-learning algorithms predict that diseases with defects in ribosomal DNA (rDNA) transcription have mitochondrial dysfunction, and, accordingly, this is found when factors involved in rDNA transcription are knocked down. Mechanistically, loss of CSA or CSB leads to polymerase stalling at non-B DNA in a neuroblastoma cell line, in particular at G-quadruplex structures, and recombinant CSB can melt G-quadruplex structures. Indeed, stabilization of G-quadruplex structures activates PARP1 and leads to accelerated aging in Caenorhabditis elegans In conclusion, this work supports a role for impaired ribosomal DNA transcription in Cockayne syndrome and suggests that transcription-coupled resolution of secondary structures may be a mechanism to repress spurious activation of a DNA damage response.

The development of structure-activity relationships for mitochondrial dysfunction: uncoupling of oxidative phosphorylation.

PubMed

Naven, Russell T; Swiss, Rachel; Klug-McLeod, Jacquelyn; Will, Yvonne; Greene, Nigel

2013-01-01

Mitochondrial dysfunction has been implicated as an important factor in the development of idiosyncratic organ toxicity. An ability to predict mitochondrial dysfunction early in the drug development process enables the deselection of those drug candidates with potential safety liabilities, allowing resources to be focused on those compounds with the highest chance of success to the market. A database of greater than 2000 compounds was analyzed to identify structural and physicochemical features associated with the uncoupling of oxidative phosphorylation (herein defined as an increase in basal respiration). Many toxicophores associated with potent uncoupling activity were identified, and these could be divided into two main mechanistic classes, protonophores and redox cyclers. For the protonophores, potent uncoupling activity was often promoted by high lipophilicity and apparent stabilization of the anionic charge resulting from deprotonation of the protonophore. The potency of redox cyclers did not appear to be prone to variations in lipophilicity. Only 11 toxicophores were of sufficient predictive performance that they could be incorporated into a structural-alert model. Each alert was associated with one of three confidence levels (high, medium, and low) depending upon the lipophilicity-activity profile of the structural class. The final model identified over 68% of those compounds with potent uncoupling activity and with a value for specificity above 99%. We discuss the advantages and limitations of this approach and conclude that although structural alert methodology is useful for identifying toxicophores associated with mitochondrial dysfunction, they are not a replacement for the mitochondrial dysfunction assays in early screening paradigms.

Mitochondrial dysfunction in brain cortex mitochondria of STZ-diabetic rats: effect of l-Arginine.

PubMed

Ortiz, M Del Carmen; Lores-Arnaiz, Silvia; Albertoni Borghese, M Florencia; Balonga, Sabrina; Lavagna, Agustina; Filipuzzi, Ana Laura; Cicerchia, Daniela; Majowicz, Monica; Bustamante, Juanita

2013-12-01

Mitochondrial dysfunction has been implicated in many diseases, including diabetes. It is well known that oxygen free radical species are produced endogenously by mitochondria, and also nitric oxide (NO) by nitric oxide synthases (NOS) associated to mitochondrial membranes, in consequence these organelles constitute main targets for oxidative damage. The aim of this study was to analyze mitochondrial physiology and NO production in brain cortex mitochondria of streptozotocin (STZ) diabetic rats in an early stage of diabetes and the potential effect of L-arginine administration. The diabetic condition was characterized by a clear hyperglycaemic state with loose of body weight after 4 days of STZ injection. This hyperglycaemic state was associated with mitochondrial dysfunction that was evident by an impairment of the respiratory activity, increased production of superoxide anion and a clear mitochondrial depolarization. In addition, the alteration in mitochondrial physiology was associated with a significant decrease in both NO production and nitric oxide synthase type I (NOS I) expression associated to the mitochondrial membranes. An increased level of thiobarbituric acid-reactive substances (TBARS) in brain cortex homogenates from STZ-diabetic rats indicated the presence of lipid peroxidation. L-arginine treatment to diabetic rats did not change blood glucose levels but significantly ameliorated the oxidative stress evidenced by lower TBARS and a lower level of superoxide anion. This effect was paralleled by improvement of mitochondrial respiratory function and a partial mitochondrial repolarization.In addition, the administration of L-arginine to diabetic rats prevented the decrease in NO production and NOSI expression. These results could indicate that exogenously administered L-arginine may have beneficial effects on mitochondrial function, oxidative stress and NO production in brain cortex mitochondria of STZ-diabetic rats.

Calcineurin Regulates Myocardial Function during Acute Endotoxemia

PubMed Central

Joshi, Mandar S.; Julian, Mark W.; Huff, Jennifer E.; Bauer, John A.; Xia, Yong; Crouser, Elliott D.

2006-01-01

Rationale: Cyclosporin A (CsA) is known to preserve cardiac contractile function during endotoxemia, but the mechanism is unclear. Increased nitric oxide (NO) production and altered mitochondrial function are implicated as mechanisms contributing to sepsis-induced cardiac dysfunction, and CsA has the capacity to reduce NO production and inhibit mitochondrial dysfunction relating to the mitochondrial permeability transition (MPT). Objectives: We hypothesized that CsA would protect against endotoxin-mediated cardiac contractile dysfunction by attenuating NO production and preserving mitochondrial function. Methods: Left ventricular function was measured continuously over 4 h in cats assigned as follows: control animals (n = 7); LPS alone (3 mg/kg, n = 8); and CsA (6 mg/kg, n = 7), a calcineurin inhibitor that blocks the MPT, or tacrolimus (FK506, 0.1 mg/kg, n = 7), a calcineurin inhibitor lacking MPT activity, followed in 30 min by LPS. Myocardial tissue was then analyzed for NO synthase-2 expression, tissue nitration, protein carbonylation, and mitochondrial morphology and function. Measurements and Main Results: LPS treatment resulted in impaired left ventricular contractility, altered mitochondrial morphology and function, and increased protein nitration. As hypothesized, CsA pretreatment normalized cardiac performance and mitochondrial respiration and reduced myocardial protein nitration. Unexpectedly, FK506 pretreatment had similar effects, normalizing both cardiac and mitochondrial parameters. However, CsA and FK506 pretreatments markedly increased protein carbonylation in the myocardium despite elevated manganese superoxide dismutase activity during endotoxemia. Conclusions: Our data indicate that calcineurin is a critical regulator of mitochondrial respiration, tissue nitration, protein carbonylation, and contractile function in the heart during acute endotoxemia. PMID:16424445

Fatigue-Related Gene Networks Identified in CD14+ Cells Isolated From HIV-Infected Patients—Part I: Research Findings

PubMed Central

Voss, Joachim G.; Dobra, Adrian; Morse, Caryn; Kovacs, Joseph A.; Danner, Robert L.; Munson, Peter J.; Logan, Carolea; Rangel, Zoila; Adelsberger, Joseph W.; McLaughlin, Mary; Adams, Larry D.; Raju, Raghavan; Dalakas, Marinos C.

2016-01-01

Purpose Human immunodeficiency virus (HIV)–related fatigue (HRF) is multicausal and potentially related to mitochondrial dysfunction caused by antiretroviral therapy with nucleoside reverse transcriptase inhibitors (NRTIs). Methodology The authors compared gene expression profiles of CD14+ cells of low versus high fatigued, NRTI-treated HIV patients to healthy controls (n = 5/group). The authors identified 32 genes predictive of low versus high fatigue and 33 genes predictive of healthy versus HIV infection. The authors constructed genetic networks to further elucidate the possible biological pathways in which these genes are involved. Relevance for nursing practice Genes including the actin cytoskeletal regulatory proteins Prokineticin 2 and Cofilin 2 along with mitochondrial inner membrane proteins are involved in multiple pathways and were predictors of fatigue status. Previously identified inflammatory and signaling genes were predictive of HIV status, clearly confirming our results and suggesting a possible further connection between mitochondrial function and HIV. Isolated CD14+ cells are easily accessible cells that could be used for further study of the connection between fatigue and mitochondrial function of HIV patients. Implication for Practice The findings from this pilot study take us one step closer to identifying biomarker targets for fatigue status and mitochondrial dysfunction. Specific biomarkers will be pertinent to the development of methodologies to diagnosis, monitor, and treat fatigue and mitochondrial dysfunction. PMID:23324479

Prospects for therapeutic mitochondrial transplantation.

PubMed

Gollihue, Jenna L; Rabchevsky, Alexander G

2017-07-01

Mitochondrial dysfunction has been implicated in a multitude of diseases and pathological conditions- the organelles that are essential for life can also be major players in contributing to cell death and disease. Because mitochondria are so well established in our existence, being present in all cell types except for red blood cells and having the responsibility of providing most of our energy needs for survival, then dysfunctional mitochondria can elicit devastating cellular pathologies that can be widespread across the entire organism. As such, the field of "mitochondrial medicine" is emerging in which disease states are being targeted therapeutically at the level of the mitochondrion, including specific antioxidants, bioenergetic substrate additions, and membrane uncoupling agents. New and compelling research investigating novel techniques for mitochondrial transplantation to replace damaged or dysfunctional mitochondria with exogenous healthy mitochondria has shown promising results, including tissue sparing accompanied by increased energy production and decreased oxidative damage. Various experimental techniques have been attempted and each has been challenged to accomplish successful transplantation. The purpose of this review is to present the history of mitochondrial transplantation, the different techniques used for both in vitro and in vivo delivery, along with caveats and pitfalls that have been discovered along the way. Results from such pioneering studies are promising and could be the next big wave of "mitochondrial medicine" once technical hurdles are overcome. Copyright © 2017 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

Defects in mitochondrial localization and ATP synthesis in the mdx mouse model of Duchenne muscular dystrophy are not alleviated by PDE5 inhibition

PubMed Central

Percival, Justin M.; Siegel, Michael P.; Knowels, Gary; Marcinek, David J.

2013-01-01

Given the crucial roles for mitochondria in ATP energy supply, Ca2+ handling and cell death, mitochondrial dysfunction has long been suspected to be an important pathogenic feature in Duchenne muscular dystrophy (DMD). Despite this foresight, mitochondrial function in dystrophin-deficient muscles has remained poorly defined and unknown in vivo. Here, we used the mdx mouse model of DMD and non-invasive spectroscopy to determine the impact of dystrophin-deficiency on skeletal muscle mitochondrial localization and oxidative phosphorylation function in vivo. Mdx mitochondria exhibited significant uncoupling of oxidative phosphorylation (reduced P/O) and a reduction in maximal ATP synthesis capacity that together decreased intramuscular ATP levels. Uncoupling was not driven by increased UCP3 or ANT1 expression. Dystrophin was required to maintain subsarcolemmal mitochondria (SSM) pool density, implicating it in the spatial control of mitochondrial localization. Given that nitric oxide-cGMP pathways regulate mitochondria and that sildenafil-mediated phosphodiesterase 5 inhibition ameliorates dystrophic pathology, we tested whether sildenafil's benefits result from decreased mitochondrial dysfunction in mdx mice. Unexpectedly, sildenafil treatment did not affect mitochondrial content or oxidative phosphorylation defects in mdx mice. Rather, PDE5 inhibition decreased resting levels of ATP, phosphocreatine and myoglobin, suggesting that sildenafil improves dystrophic pathology through other mechanisms. Overall, these data indicate that dystrophin-deficiency disrupts SSM localization, promotes mitochondrial inefficiency and restricts maximal mitochondrial ATP-generating capacity. Together these defects decrease intramuscular ATP and the ability of mdx muscle mitochondria to meet ATP demand. These findings further understanding of how mitochondrial bioenergetic dysfunction contributes to disease pathogenesis in dystrophin-deficient skeletal muscle in vivo. PMID:23049075

Altered mitochondrial acetylation profiles in a kainic acid model of temporal lobe epilepsy.

PubMed

Gano, Lindsey B; Liang, Li-Ping; Ryan, Kristen; Michel, Cole R; Gomez, Joe; Vassilopoulos, Athanassios; Reisdorph, Nichole; Fritz, Kristofer S; Patel, Manisha

2018-08-01

Impaired bioenergetics and oxidative damage in the mitochondria are implicated in the etiology of temporal lobe epilepsy, and hyperacetylation of mitochondrial proteins has recently emerged as a critical negative regulator of mitochondrial functions. However, the roles of mitochondrial acetylation and activity of the primary mitochondrial deacetylase, SIRT3, have not been explored in acquired epilepsy. We investigated changes in mitochondrial acetylation and SIRT3 activity in the development of chronic epilepsy in the kainic acid rat model of TLE. Hippocampal measurements were made at 48 h, 1 week and 12 weeks corresponding to the acute, latent and chronic stages of epileptogenesis. Assessment of hippocampal bioenergetics demonstrated a ≥ 27% decrease in the ATP/ADP ratio at all phases of epileptogenesis (p < 0.05), whereas cellular NAD+ levels were decreased by ≥ 41% in the acute and latent time points (p < 0.05), but not in chronically epileptic rats. In spontaneously epileptic rats, we found decreased protein expression of SIRT3 and a 60% increase in global mitochondrial acetylation, as well as enhanced acetylation of the known SIRT3 substrates MnSOD, Ndufa9 of Complex I and IDH2 (all p < 0.05), suggesting SIRT3 dysfunction in chronic epilepsy. Mass spectrometry-based acetylomics investigation of hippocampal mitochondria demonstrated a 79% increase in unique acetylated proteins from rats in the chronic phase vs. controls. Pathway analysis identified numerous mitochondrial bioenergetic pathways affected by mitochondrial acetylation. These results suggest SIRT3 dysfunction and aberrant protein acetylation may contribute to mitochondrial dysfunction in chronic epilepsy. Copyright © 2018 Elsevier Inc. All rights reserved.

Mitochondrial iron-sulfur cluster biogenesis from molecular understanding to clinical disease

PubMed Central

Alfadhel, Majid; Nashabat, Marwan; Ali, Qais Abu; Hundallah, Khalid

2017-01-01

Iron–sulfur clusters (ISCs) are known to play a major role in various protein functions. Located in the mitochondria, cytosol, endoplasmic reticulum and nucleus, they contribute to various core cellular functions. Until recently, only a few human diseases related to mitochondrial ISC biogenesis defects have been described. Such diseases include Friedreich ataxia, combined oxidative phosphorylation deficiency 19, infantile complex II/III deficiency defect, hereditary myopathy with lactic acidosis and mitochondrial muscle myopathy, lipoic acid biosynthesis defects, multiple mitochondrial dysfunctions syndromes and non ketotic hyperglycinemia due to glutaredoxin 5 gene defect. Disorders of mitochondrial import, export and translation, including sideroblastic anemia with ataxia, EVEN-PLUS syndrome and mitochondrial complex I deficiency due to nucleotide-binding protein-like protein gene defect, have also been implicated in ISC biogenesis defects. With advances in next generation sequencing technologies, more disorders related to ISC biogenesis defects are expected to be elucidated. In this article, we aim to shed the light on mitochondrial ISC biogenesis, related proteins and their function, pathophysiology, clinical phenotypes of related disorders, diagnostic approach, and future implications. PMID:28064324

Statin Adverse Effects: A Review of the Literature and Evidence for a Mitochondrial Mechanism

PubMed Central

Golomb, Beatrice A.; Evans, Marcella A.

2009-01-01

HMG-CoA reductase inhibitors (statins) are a widely used class of drug, and like all medications have potential for adverse effects (AEs). Here we review the statin AE literature, first focusing on muscle AEs as the most reported problem both in the literature and by patients. Evidence regarding the statin muscle AE mechanism, dose effect, drug interactions, and genetic predisposition is examined. We hypothesize, and provide evidence, that the demonstrated mitochondrial mechanisms for muscle AEs have implications to other nonmuscle AEs in patients treated with statins. In meta-analyses of randomized controlled trials (RCTs), muscle AEs are more frequent with statins than with placebo. A number of manifestations of muscle AEs have been reported, with rhabdomyolysis the most feared. AEs are dose dependent, and risk is amplified by drug interactions that functionally increase statin potency, often through inhibition of the cytochrome P450 (CYP)3A4 system. An array of additional risk factors for statin AEs are those that amplify (or reflect) mitochondrial or metabolic vulnerability, such as metabolic syndrome factors, thyroid disease, and genetic mutations linked to mitochondrial dysfunction. Converging evidence supports a mitochondrial foundation for muscle AEs associated with statins, and both theoretical and empirical considerations suggest that mitochondrial dysfunction may also underlie many non-muscle statin AEs. Evidence from RCTs and studies of other designs indicates existence of additional statin-associated AEs, such as cognitive loss, neuropathy, pancreatic and hepatic dysfunction, and sexual dysfunction. Physician awareness of statin AEs is reportedly low even for the AEs most widely reported by patients. Awareness and vigilance for AEs should be maintained to enable informed treatment decisions, treatment modification if appropriate, improved quality of patient care, and reduced patient morbidity. PMID:19159124

The Spectrum of Mitochondrial Ultrastructural Defects in Mitochondrial Myopathy

PubMed Central

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

2016-01-01

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

Higher Vulnerability of Menadione-Exposed Cortical Astrocytes of Glutaryl-CoA Dehydrogenase Deficient Mice to Oxidative Stress, Mitochondrial Dysfunction, and Cell Death: Implications for the Neurodegeneration in Glutaric Aciduria Type I.

PubMed

Rodrigues, Marília Danyelle Nunes; Seminotti, Bianca; Zanatta, Ângela; de Mello Gonçalves, Aline; Bellaver, Bruna; Amaral, Alexandre Umpierrez; Quincozes-Santos, André; Goodman, Stephen Irwin; Woontner, Michael; Souza, Diogo Onofre; Wajner, Moacir

2017-08-01

Patients affected by glutaric aciduria type I (GA-I) show progressive cortical leukoencephalopathy whose pathogenesis is poorly known. In the present work, we exposed cortical astrocytes of wild-type (Gcdh +/+ ) and glutaryl-CoA dehydrogenase knockout (Gcdh -/- ) mice to the oxidative stress inducer menadione and measured mitochondrial bioenergetics, redox homeostasis, and cell viability. Mitochondrial function (MTT and JC1-mitochondrial membrane potential assays), redox homeostasis (DCFH oxidation, nitrate and nitrite production, GSH concentrations and activities of the antioxidant enzymes SOD and GPx), and cell death (propidium iodide incorporation) were evaluated in primary cortical astrocyte cultures of Gcdh +/+ and Gcdh -/- mice unstimulated and stimulated by menadione. We also measured the pro-inflammatory response (TNFα levels, IL1-β and NF-ƙB) in unstimulated astrocytes obtained from these mice. Gcdh -/- mice astrocytes were more vulnerable to menadione-induced oxidative stress (decreased GSH concentrations and altered activities of the antioxidant enzymes), mitochondrial dysfunction (decrease of MTT reduction and JC1 values), and cell death as compared with Gcdh +/+ astrocytes. A higher inflammatory response (TNFα, IL1-β and NF-ƙB) was also observed in Gcdh -/- mice astrocytes. These data indicate a higher susceptibility of Gcdh -/- cortical astrocytes to oxidative stress and mitochondrial dysfunction, probably leading to cell death. It is presumed that these pathomechanisms may contribute to the cortical leukodystrophy observed in GA-I patients.

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.

The Measurement of Reversible Redox Dependent Post-translational Modifications and Their Regulation of Mitochondrial and Skeletal Muscle Function

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

Kramer, Philip A.; Duan, Jicheng; Qian, Wei-Jun

Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifications (PTMs) in pathophysiology is emerging. The possibility that these PTMs can exert dynamic control of muscle function implicates them as a mechanism contributing to skeletal muscle dysfunction in chronic disease. Herein, we discuss the significance of thiol-based redox dependent modifications to mitochondrial, myofibrillar and excitation-contraction (EC) coupling proteins with an emphasis on howmore » these changes could alter skeletal muscle performance under chronically stressed conditions. A major barrier to a better mechanistic understanding of the role of reversible redox PTMs in muscle function is the technical challenges associated with accurately measuring the changes of site-specific redox PTMs. Here we will critically review current approaches with an emphasis on sample preparation artifacts, quantitation, and specificity. Despite these challenges, the ability to accurately quantify reversible redox PTMs is critical to understanding the mechanisms by which mitochondrial oxidative stress contributes to skeletal muscle dysfunction in chronic diseases.« less

Mitochondrial dysfunction in blood cells from amyotrophic lateral sclerosis patients.

PubMed

Ehinger, Johannes K; Morota, Saori; Hansson, Magnus J; Paul, Gesine; Elmér, Eskil

2015-06-01

Mitochondrial dysfunction is implicated in amyotrophic lateral sclerosis, where the progressive degeneration of motor neurons results in muscle atrophy, paralysis and death. Abnormalities in both central nervous system and muscle mitochondria have previously been demonstrated in patient samples, indicating systemic disease. In this case-control study, venous blood samples were acquired from 24 amyotrophic lateral sclerosis patients and 21 age-matched controls. Platelets and peripheral blood mononuclear cells were isolated and mitochondrial oxygen consumption measured in intact and permeabilized cells with additions of mitochondrial substrates, inhibitors and titration of an uncoupler. Respiratory values were normalized to cell count and for two markers of cellular mitochondrial content, citrate synthase activity and mitochondrial DNA, respectively. Mitochondrial function was correlated with clinical staging of disease severity. Complex IV (cytochrome c-oxidase)-activity normalized to mitochondrial content was decreased in platelets from amyotrophic lateral sclerosis patients both when normalized to citrate synthase activity and mitochondrial DNA copy number. In mononuclear cells, complex IV-activity was decreased when normalized to citrate synthase activity. Mitochondrial content was increased in amyotrophic lateral sclerosis patient platelets. In mononuclear cells, complex I activity declined and mitochondrial content increased progressively with advancing disease stage. The findings are, however, based on small subsets of patients and need to be confirmed. We conclude that when normalized to mitochondria-specific content, complex IV-activity is reduced in blood cells from amyotrophic lateral sclerosis patients and that there is an apparent compensatory increase in cellular mitochondrial content. This supports systemic involvement in amyotrophic lateral sclerosis and suggests further study of mitochondrial function in blood cells as a future biomarker for the disease.

Rotenone, Paraquat, and Parkinson’s Disease

PubMed Central

Tanner, Caroline M.; Kamel, Freya; Ross, G. Webster; Hoppin, Jane A.; Goldman, Samuel M.; Korell, Monica; Marras, Connie; Bhudhikanok, Grace S.; Kasten, Meike; Chade, Anabel R.; Comyns, Kathleen; Richards, Marie Barber; Meng, Cheryl; Priestley, Benjamin; Fernandez, Hubert H.; Cambi, Franca; Umbach, David M.; Blair, Aaron; Sandler, Dale P.; Langston, J. William

2011-01-01

Background Mitochondrial dysfunction and oxidative stress are pathophysiologic mechanisms implicated in experimental models and genetic forms of Parkinson’s disease (PD). Certain pesticides may affect these mechanisms, but no pesticide has been definitively associated with PD in humans. Objectives Our goal was to determine whether pesticides that cause mitochondrial dysfunction or oxidative stress are associated with PD or clinical features of parkinsonism in humans. Methods We assessed lifetime use of pesticides selected by mechanism in a case–control study nested in the Agricultural Health Study (AHS). PD was diagnosed by movement disorders specialists. Controls were a stratified random sample of all AHS participants frequency-matched to cases by age, sex, and state at approximately three controls: one case. Results In 110 PD cases and 358 controls, PD was associated with use of a group of pesticides that inhibit mitochondrial complex I [odds ratio (OR) = 1.7; 95% confidence interval (CI), 1.0–2.8] including rotenone (OR = 2.5; 95% CI, 1.3–4.7) and with use of a group of pesticides that cause oxidative stress (OR = 2.0; 95% CI, 1.2–3.6), including paraquat (OR = 2.5; 95% CI, 1.4–4.7). Conclusions PD was positively associated with two groups of pesticides defined by mechanisms implicated experimentally—those that impair mitochondrial function and those that increase oxidative stress—supporting a role for these mechanisms in PD pathophysiology. PMID:21269927

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

Differential programming of p53-deficient embryonic cells during rotenone block

EPA Science Inventory

Mitochondrial dysfunction has been implicated in chemical toxicities. The present study used an in vitro model to investigate the differential expression of metabolic pathways during cellular stress in p53- efficient embryonic fibroblasts compared to p53-deficient cells. These c...

Skeletal muscle action of estrogen receptor α is critical for the maintenance of mitochondrial function and metabolic homeostasis in females

PubMed Central

Ribas, Vicent; Drew, Brian G.; Zhou, Zhenqi; Phun, Jennifer; Kalajian, Nareg Y.; Soleymani, Teo; Daraei, Pedram; Widjaja, Kevin; Wanagat, Jonathan; de Aguiar Vallim, Thomas Q.; Fluitt, Amy H.; Bensinger, Steven; Le, Thuc; Radu, Caius; Whitelegge, Julian P.; Beaven, Simon W.; Tontonoz, Peter; Lusis, Aldons J.; Parks, Brian W.; Vergnes, Laurent; Reue, Karen; Singh, Harpreet; Bopassa, Jean C.; Toro, Ligia; Stefani, Enrico; Watt, Matthew J.; Schenk, Simon; Akerstrom, Thorbjorn; Kelly, Meghan; Pedersen, Bente K.; Hewitt, Sylvia C.; Korach, Kenneth S.; Hevener, Andrea L.

2016-01-01

Impaired estrogen receptor α(ERα) action promotes obesity and metabolic dysfunction in humans and mice; however, the mechanisms underlying these phenotypes remain unknown. Considering that skeletal muscle is a primary tissue responsible for glucose disposal and oxidative metabolism, we established that reduced ERαexpression in muscle is associated with glucose intolerance and adiposity in women and female mice. To test this relationship, we generated muscle-specific ERαknockout (MERKO) mice. Impaired glucose homeostasis and increased adiposity were paralleled by diminished muscle oxidative metabolism and bioactive lipid accumulation in MERKO mice. Aberrant mitochondrial morphology, overproduction of reactive oxygen species, and impairment in basal and stress-induced mitochondrial fission dynamics, driven by imbalanced protein kinase A–regulator of calcineurin 1–calcineurin signaling through dynamin-related protein 1, tracked with reduced oxidative metabolism in MERKO muscle. Although muscle mitochondrial DNA (mtDNA) abundance was similar between the genotypes, ERαdeficiency diminished mtDNA turnover by a balanced reduction in mtDNA replication and degradation. Our findings indicate the retention of dysfunctional mitochondria in MERKO muscle and implicate ERαin the preservation of mitochondrial health and insulin sensitivity as a defense against metabolic disease in women. PMID:27075628

Inhibition of neuroinflammation and mitochondrial dysfunctions by carbenoxolone in the rotenone model of Parkinson's disease.

PubMed

Thakur, Poonam; Nehru, Bimla

2015-02-01

α-Synuclein aggregation contributes to the Parkinson's disease (PD) pathology in multiple ways-the two most important being the activation of neuroinflammation and mitochondrial dysfunction. Our recent studies have shown the beneficial effects of a heat shock protein (HSP) inducer, carbenoxolone (Cbx), in reducing the aggregation of α-synuclein in a rotenone-based rat model of PD. The present study was designed to explore its ability to attenuate the α-synuclein-mediated alterations in neuroinflammation and mitochondrial functions. The PD model was generated by the rotenone administration (2 mg/kg b.wt.) to the male SD rats for a period of 5 weeks. Cbx (20 mg/kg b.wt.) co-administration was seen to reduce the activation of astrocytes incited by rotenone. Subsequently, the release of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β was inhibited. Further, the expression level of various inflammatory mediators such as COX-2, iNOS, and NF-κB was also reduced following Cbx co-treatment. Cbx was also shown to reduce the rotenone-induced decline in activity of mitochondrial complexes-I, -II, and -IV. Protection of mitochondrial functions and reduction in neuroinflammation lead to the lesser production of ROS and subsequently reduced oxidative stress. This was reflected by the increase in both the cytosolic and mitochondrial GSH levels as well as SOD activity during Cbx co-treatment. Thus, Cbx reduces the inflammatory response and improves the mitochondrial dysfunctions by reducing α-synuclein aggregation. In addition, it also reduces the associated oxidative stress. Due to its ability to target the multiple pathways implicated in the PD, Cbx can serve as a highly beneficial prophylactic agent.

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

Beneficial effect of the bioflavonoid quercetin on cholecystokinin-induced mitochondrial dysfunction in isolated rat pancreatic acinar cells.

PubMed

Weber, Heike; Jonas, Ludwig; Wakileh, Michael; Krüger, Burkhard

2014-03-01

The pathogenesis of acute pancreatitis (AP) is still poorly understood. Thus, a reliable pharmacological therapy is currently lacking. In recent years, an impairment of the energy metabolism of pancreatic acinar cells, caused by Ca(2+)-mediated depolarization of the inner mitochondrial membrane and a decreased ATP supply, has been implicated as an important pathological event. In this study, we investigated whether quercetin exerts protection against mitochondrial dysfunction. Following treatment with or without quercetin, rat pancreatic acinar cells were stimulated with supramaximal cholecystokinin-8 (CCK). CCK caused a decrease in the mitochondrial membrane potential (MMP) and ATP concentration, whereas the mitochondrial dehydrogenase activity was significantly increased. Quercetin treatment before CCK application exerted no protection on MMP but increased ATP to a normal level, leading to a continuous decrease in the dehydrogenase activity. The protective effect of quercetin on mitochondrial function was accompanied by a reduction in CCK-induced changes to the cell membrane. Concerning the molecular mechanism underlying the protective effect of quercetin, an increased AMP/ATP ratio suggests that the AMP-activated protein kinase system may be activated. In addition, quercetin strongly inhibited CCK-induced trypsin activity. The results indicate that the use of quercetin may be a therapeutic strategy for reducing the severity of AP.

Unraveling Biochemical Pathways Affected by Mitochondrial Dysfunctions Using Metabolomic Approaches

PubMed Central

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

2014-01-01

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

Frontal cortical mitochondrial dysfunction and mitochondria-related β-amyloid accumulation by chronic sleep restriction in mice.

PubMed

Zhao, Hongyi; Wu, Huijuan; He, Jialin; Zhuang, Jianhua; Liu, Zhenyu; Yang, Yang; Huang, Liuqing; Zhao, Zhongxin

2016-08-17

Mitochondrial dysfunction induced by mitochondria-related β-amyloid (Aβ) accumulation is increasingly being considered a novel risk factor for sporadic Alzheimer's disease pathophysiology. The close relationship between chronic sleep restriction (CSR) and cortical Aβ elevation was confirmed recently. By assessing frontal cortical mitochondrial function (electron microscopy manifestation, cytochrome C oxidase concentration, ATP level, and mitochondrial membrane potential) and the levels of mitochondria-related Aβ in 9-month-old adult male C57BL/6J mice subjected to CSR and as an environmental control (CO) group, we aimed to evaluate the association of CSR with mitochondrial dysfunction and mitochondria-related Aβ accumulation. In this study, frontal cortical mitochondrial dysfunction was significantly more severe in CSR mice compared with CO animals. Furthermore, CSR mice showed higher mitochondria-associated Aβ, total Aβ, and mitochondria-related β-amyloid protein precursor (AβPP) levels compared with CO mice. In the CSR model, mouse frontal cortical mitochondrial dysfunction was correlated with mitochondria-associated Aβ and mitochondria-related AβPP levels. However, frontal cortical mitochondria-associated Aβ levels showed no significant association with cortical total Aβ and mitochondrial AβPP concentrations. These findings indicated that CSR-induced frontal cortical mitochondrial dysfunction and mitochondria-related Aβ accumulation, which was closely related to mitochondrial dysfunction under CSR.

Mitochondrial control of cell bioenergetics in Parkinson’s disease

PubMed Central

Requejo-Aguilar, Raquel; Bolaños, Juan P.

2016-01-01

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

Genetically enhancing mitochondrial antioxidant activity improves muscle function in aging

PubMed Central

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

2014-01-01

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

DJ-1 KNOCK-DOWN IMPAIRS ASTROCYTE MITOCHONDRIAL FUNCTION

PubMed Central

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

2012-01-01

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

Measurement of Oxidative Stress: Mitochondrial Function Using the Seahorse System.

PubMed

Leung, Dilys T H; Chu, Simon

2018-01-01

The Seahorse XFp Analyzer is a powerful tool for the assessment of various parameters of cellular respiration. Here we describe the process of the Seahorse Cell Phenotype Test using the Seahorse XFp Analyzer to characterize the metabolic phenotype of live cells. The Seahorse XFp Analyzer can also be coupled with other assays to measure cellular energetics. Given that mitochondrial dysfunction is implicated in preeclampsia, the Seahorse XFp Analyzer will serve as a useful tool for the understanding of pathological metabolism in this disorder.

Association of Common Mitochondrial DNA Variants with Multiple Sclerosis and Systemic Lupus Erythematosus

PubMed Central

Vyshkina, Tamara; Sylvester, Andrew; Sadiq, Saud; Bonilla, Eduardo; Canter, Jeff A.; Perl, Andras; Kalman, Bernadette

2008-01-01

Mitochondrial dysfunction has been implicated in the pathogenesis of multiple sclerosis (MS) and systemic lupus erythematosus (SLE). This study re-investigates the roles of previously suggested candidate genes of energy metabolism (Complex I genes located in the nucleus and in the mitochondria) in patients with MS relative to ethnically matched SLE patients and healthy controls. After stringent correction for multiple testing, we reproduce the association of the mitochondrial (mt)DNA haplotype K* with MS, but reject the importance of previously suggested borderline associations with nuclear genes of Complex I. In addition, we detect the association of common variants of the mitochondrial ND2 and ATP6 genes with both MS and SLE, which raises the possibility of a shared mitochondrial genetic background of these two autoimmune diseases. PMID:18708297

Drp1-Dependent Mitochondrial Autophagy Plays a Protective Role Against Pressure Overload-Induced Mitochondrial Dysfunction and Heart Failure.

PubMed

Shirakabe, Akihiro; Zhai, Peiyong; Ikeda, Yoshiyuki; Saito, Toshiro; Maejima, Yasuhiro; Hsu, Chiao-Po; Nomura, Masatoshi; Egashira, Kensuke; Levine, Beth; Sadoshima, Junichi

2016-03-29

Mitochondrial autophagy is an important mediator of mitochondrial quality control in cardiomyocytes. The occurrence of mitochondrial autophagy and its significance during cardiac hypertrophy are not well understood. Mice were subjected to transverse aortic constriction (TAC) and observed at multiple time points up to 30 days. Cardiac hypertrophy developed after 5 days, the ejection fraction was reduced after 14 days, and heart failure was observed 30 days after TAC. General autophagy was upregulated between 1 and 12 hours after TAC but was downregulated below physiological levels 5 days after TAC. Mitochondrial autophagy, evaluated by electron microscopy, mitochondrial content, and Keima with mitochondrial localization signal, was transiently activated at ≈3 to 7 days post-TAC, coinciding with mitochondrial translocation of Drp1. However, it was downregulated thereafter, followed by mitochondrial dysfunction. Haploinsufficiency of Drp1 abolished mitochondrial autophagy and exacerbated the development of both mitochondrial dysfunction and heart failure after TAC. Injection of Tat-Beclin 1, a potent inducer of autophagy, but not control peptide, on day 7 after TAC, partially rescued mitochondrial autophagy and attenuated mitochondrial dysfunction and heart failure induced by overload. Haploinsufficiency of either drp1 or beclin 1 prevented the rescue by Tat-Beclin 1, suggesting that its effect is mediated in part through autophagy, including mitochondrial autophagy. Mitochondrial autophagy is transiently activated and then downregulated in the mouse heart in response to pressure overload. Downregulation of mitochondrial autophagy plays an important role in mediating the development of mitochondrial dysfunction and heart failure, whereas restoration of mitochondrial autophagy attenuates dysfunction in the heart during pressure overload. © 2016 American Heart Association, Inc.

Bisphenol A induces oxidative stress and mitochondrial dysfunction in lymphoblasts from children with autism and unaffected siblings.

PubMed

Kaur, Kulbir; Chauhan, Ved; Gu, Feng; Chauhan, Abha

2014-11-01

Autism is a behaviorally defined neurodevelopmental disorder. Although there is no single identifiable cause for autism, roles for genetic and environmental factors have been implicated in autism. Extensive evidence suggests increased oxidative stress and mitochondrial dysfunction in autism. In this study, we examined whether bisphenol A (BPA) is an environmental risk factor for autism by studying its effects on oxidative stress and mitochondrial function in the lymphoblasts. When lymphoblastoid cells from autistic subjects and age-matched unaffected sibling controls were exposed to BPA, there was an increase in the generation of reactive oxygen species (ROS) and a decrease in mitochondrial membrane potential in both groups. A further subdivision of the control group into two subgroups-unaffected nontwin siblings and twin siblings-showed significantly higher ROS levels without any exposure to BPA in the unaffected twin siblings compared to the unaffected nontwin siblings. ROS levels were also significantly higher in the autism vs the unaffected nontwin siblings group. The effect of BPA on three important mtDNA genes-NADH dehydrogenase 1, NADH dehydrogenase 4, and cytochrome b-was analyzed to observe any changes in the mitochondria after BPA exposure. BPA induced a significant increase in the mtDNA copy number in the lymphoblasts from the unaffected siblings group and in the unaffected twin siblings group vs the unaffected nontwin siblings. In all three genes, the mtDNA increase was seen in 70% of the subjects. These results suggest that BPA exposure results in increased oxidative stress and mitochondrial dysfunction in the autistic subjects as well as the age-matched sibling control subjects, particularly unaffected twin siblings. Therefore, BPA may act as an environmental risk factor for autism in genetically susceptible children by inducing oxidative stress and mitochondrial dysfunction. Copyright © 2014 Elsevier Inc. All rights reserved.

Mitochondrial Replacement Therapy in Reproductive Medicine

PubMed Central

Wolf, Don P.; Mitalipov, Nargiz; Mitalipov, Shoukhrat

2015-01-01

Mitochondrial dysfunction is implicated in disease and in age-related infertility. Mitochondrial replacement therapies (MRT) in oocytes or zygotes such as pronuclear (PNT), spindle (ST) or polar body (PBT) transfer could prevent second generation transmission of mitochondrial DNA (mtDNA) defects. PNT, associated with high levels of mtDNA carryover in mice but low levels in human embryos, carries ethical issues secondary to donor embryo destruction. ST, developed in primates, supports normal development to adults and low mtDNA carryover. PBT in mice, coupled with PN or ST, may increase the yield of reconstructed embryos with low mtDNA carryover. MRT also offers replacement of the deficient cytoplasm in oocytes from older patients, with the expectation of high pregnancy rates following in vitro fertilization. PMID:25573721

Ischemia-induced endothelial cell swelling and mitochondrial dysfunction are attenuated by dietary polyphenols in vitro

USDA-ARS?s Scientific Manuscript database

Polyphenols possess anti-oxidant and anti-inflammatory properties. Oxidative stress (OS) and inflammation have been implicated in the pathogenesis of cytotoxic brain edema in cerebral ischemia. In addition, OS and pro-inflammatory cytokines also damage the endothelial cells and the neurovascular uni...

Mitochondrial dysfunction in autism spectrum disorders: a systematic review and meta-analysis

PubMed Central

Rossignol, D A; Frye, R E

2012-01-01

A comprehensive literature search was performed to collate evidence of mitochondrial dysfunction in autism spectrum disorders (ASDs) with two primary objectives. First, features of mitochondrial dysfunction in the general population of children with ASD were identified. Second, characteristics of mitochondrial dysfunction in children with ASD and concomitant mitochondrial disease (MD) were compared with published literature of two general populations: ASD children without MD, and non-ASD children with MD. The prevalence of MD in the general population of ASD was 5.0% (95% confidence interval 3.2, 6.9%), much higher than found in the general population (∼0.01%). The prevalence of abnormal biomarker values of mitochondrial dysfunction was high in ASD, much higher than the prevalence of MD. Variances and mean values of many mitochondrial biomarkers (lactate, pyruvate, carnitine and ubiquinone) were significantly different between ASD and controls. Some markers correlated with ASD severity. Neuroimaging, in vitro and post-mortem brain studies were consistent with an elevated prevalence of mitochondrial dysfunction in ASD. Taken together, these findings suggest children with ASD have a spectrum of mitochondrial dysfunction of differing severity. Eighteen publications representing a total of 112 children with ASD and MD (ASD/MD) were identified. The prevalence of developmental regression (52%), seizures (41%), motor delay (51%), gastrointestinal abnormalities (74%), female gender (39%), and elevated lactate (78%) and pyruvate (45%) was significantly higher in ASD/MD compared with the general ASD population. The prevalence of many of these abnormalities was similar to the general population of children with MD, suggesting that ASD/MD represents a distinct subgroup of children with MD. Most ASD/MD cases (79%) were not associated with genetic abnormalities, raising the possibility of secondary mitochondrial dysfunction. Treatment studies for ASD/MD were limited, although improvements were noted in some studies with carnitine, co-enzyme Q10 and B-vitamins. Many studies suffered from limitations, including small sample sizes, referral or publication biases, and variability in protocols for selecting children for MD workup, collecting mitochondrial biomarkers and defining MD. Overall, this evidence supports the notion that mitochondrial dysfunction is associated with ASD. Additional studies are needed to further define the role of mitochondrial dysfunction in ASD. PMID:21263444

Integrated genomic approaches identify major pathways and upstream regulators in late onset Alzheimer’s disease

PubMed Central

Li, Xinzhong; Long, Jintao; He, Taigang; Belshaw, Robert; Scott, James

2015-01-01

Previous studies have evaluated gene expression in Alzheimer’s disease (AD) brains to identify mechanistic processes, but have been limited by the size of the datasets studied. Here we have implemented a novel meta-analysis approach to identify differentially expressed genes (DEGs) in published datasets comprising 450 late onset AD (LOAD) brains and 212 controls. We found 3124 DEGs, many of which were highly correlated with Braak stage and cerebral atrophy. Pathway Analysis revealed the most perturbed pathways to be (a) nitric oxide and reactive oxygen species in macrophages (NOROS), (b) NFkB and (c) mitochondrial dysfunction. NOROS was also up-regulated, and mitochondrial dysfunction down-regulated, in healthy ageing subjects. Upstream regulator analysis predicted the TLR4 ligands, STAT3 and NFKBIA, for activated pathways and RICTOR for mitochondrial genes. Protein-protein interaction network analysis emphasised the role of NFKB; identified a key interaction of CLU with complement; and linked TYROBP, TREM2 and DOK3 to modulation of LPS signalling through TLR4 and to phosphatidylinositol metabolism. We suggest that NEUROD6, ZCCHC17, PPEF1 and MANBAL are potentially implicated in LOAD, with predicted links to calcium signalling and protein mannosylation. Our study demonstrates a highly injurious combination of TLR4-mediated NFKB signalling, NOROS inflammatory pathway activation, and mitochondrial dysfunction in LOAD. PMID:26202100

Neuroprotective Effect of Ginkgolide B on Bupivacaine-Induced Apoptosis in SH-SY5Y Cells

PubMed Central

Li, Le; Zhang, Qing-guo; Lai, Lu-ying; Wen, Xian-jie; Zheng, Ting; Cheung, Chi-wai; Zhou, Shu-qin; Xu, Shi-yuan

2013-01-01

Local anesthetics are used routinely and effectively. However, many are also known to activate neurotoxic pathways. We tested the neuroprotective efficacy of ginkgolide B (GB), an active component of Ginkgo biloba, against ROS-mediated neurotoxicity caused by the local anesthetic bupivacaine. SH-SY5Y cells were treated with different concentrations of bupivacaine alone or following preincubation with GB. Pretreatment with GB increased SH-SY5Y cell viability and attenuated intracellular ROS accumulation, apoptosis, mitochondrial dysfunction, and ER stress. GB suppressed bupivacaine-induced mitochondrial depolarization and mitochondria complex I and III inhibition and increased cleaved caspase-3 and Htra2 expression, which was strongly indicative of activation of mitochondria-dependent apoptosis with concomitantly enhanced expressions of Grp78, caspase-12 mRNA, protein, and ER stress. GB also improved ultrastructural changes indicative of mitochondrial and ER damage induced by bupivacaine. These results implicate bupivacaine-induced ROS-dependent mitochondria, ER dysfunction, and apoptosis, which can be attenuated by GB through its antioxidant property. PMID:24228138

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-11-08

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

Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence.

PubMed

Tai, Haoran; Wang, Zhe; Gong, Hui; Han, Xiaojuan; Zhou, Jiao; Wang, Xiaobo; Wei, Xiawei; Ding, Yi; Huang, Ning; Qin, Jianqiong; Zhang, Jie; Wang, Shuang; Gao, Fei; Chrzanowska-Lightowlers, Zofia M; Xiang, Rong; Xiao, Hengyi

2017-01-02

Macroautophagy/autophagy has profound implications for aging. However, the true features of autophagy in the progression of aging remain to be clarified. In the present study, we explored the status of autophagic flux during the development of cell senescence induced by oxidative stress. In this system, although autophagic structures increased, the degradation of SQSTM1/p62 protein, the yellow puncta of mRFP-GFP-LC3 fluorescence and the activity of lysosomal proteolytic enzymes all decreased in senescent cells, indicating impaired autophagic flux with lysosomal dysfunction. The influence of autophagy activity on senescence development was confirmed by both positive and negative autophagy modulators; and MTOR-dependent autophagy activators, rapamycin and PP242, efficiently suppressed cellular senescence through a mechanism relevant to restoring autophagic flux. By time-phased treatment of cells with the antioxidant N-acetylcysteine (NAC), the mitochondria uncoupler carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and ambroxol, a reagent with the effect of enhancing lysosomal enzyme maturation, we found that mitochondrial dysfunction plays an initiating role, while lysosomal dysfunction is more directly responsible for autophagy impairment and senescence. Interestingly, the effect of rapamycin on autophagy flux is linked to its role in functional revitalization of both mitochondrial and lysosomal functions. Together, this study demonstrates that autophagy impairment is crucial for oxidative stress-induced cell senescence, thus restoring autophagy activity could be a promising way to retard senescence.

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

PubMed Central

Swerdlow, Russell H.

2012-01-01

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

RIP1-mediated mitochondrial dysfunction and ROS production contributed to tumor necrosis factor alpha-induced L929 cell necroptosis and autophagy.

PubMed

Ye, Yuan-Chao; Wang, Hong-Ju; Yu, Lu; Tashiro, Shin-Ichi; Onodera, Satoshi; Ikejima, Takashi

2012-12-01

Tumor necrosis factor alpha (TNFα) induces necroptosis and autophagy; however, the detailed molecular mechanism is not fully understood. In this study, we found that TNFα administration caused mitochondrial dysfunction and reactive oxygen species (ROS) production, which led to necroptosis and autophagy in murine fibrosarcoma L929 cells. Notably, the RIP1 (serine-threonine kinase receptor-interacting protein 1, a main adaptor protein of necroptosis) specific inhibitor necrostatin-1 (Nec-1) recovered mitochondrial dysfunction and ROS production due to TNFα administration. Moreover, pan-caspase inhibitor z-VAD-fmk (zVAD) increased RIP1 expression and exacerbated TNFα-induced mitochondrial dysfunction and ROS production, indicating that RIP1 led to mitochondrial dysfunction and ROS production. In addition, cytochrome c release from mitochondria was accompanied with TNFα administration, and Nec-1 blocked the release of cytochrome c upon TNFα administration, while zVAD enhanced the release. These further suggested that RIP1 induced mitochondrial dysfunction accompanied with cytochrome c release. Furthermore, autophagy inhibitor 3-methyladenine (3MA) did not affect RIP1 expression as well as mitochondrial dysfunction and ROS production. Together with our previous publication that autophagy was a downstream consequence of necroptosis, we concluded that TNFα induced mitochondrial dysfunction accompanied with ROS production and cytochrome c release via RIP1, leading to necroptosis and resulting autophagic cell death. Copyright © 2012 Elsevier B.V. All rights reserved.

Skeletal muscle action of estrogen receptor α is critical for the maintenance of mitochondrial function and metabolic homeostasis in females.

PubMed

Ribas, Vicent; Drew, Brian G; Zhou, Zhenqi; Phun, Jennifer; Kalajian, Nareg Y; Soleymani, Teo; Daraei, Pedram; Widjaja, Kevin; Wanagat, Jonathan; de Aguiar Vallim, Thomas Q; Fluitt, Amy H; Bensinger, Steven; Le, Thuc; Radu, Caius; Whitelegge, Julian P; Beaven, Simon W; Tontonoz, Peter; Lusis, Aldons J; Parks, Brian W; Vergnes, Laurent; Reue, Karen; Singh, Harpreet; Bopassa, Jean C; Toro, Ligia; Stefani, Enrico; Watt, Matthew J; Schenk, Simon; Akerstrom, Thorbjorn; Kelly, Meghan; Pedersen, Bente K; Hewitt, Sylvia C; Korach, Kenneth S; Hevener, Andrea L

2016-04-13

Impaired estrogen receptor α (ERα) action promotes obesity and metabolic dysfunction in humans and mice; however, the mechanisms underlying these phenotypes remain unknown. Considering that skeletal muscle is a primary tissue responsible for glucose disposal and oxidative metabolism, we established that reduced ERα expression in muscle is associated with glucose intolerance and adiposity in women and female mice. To test this relationship, we generated muscle-specific ERα knockout (MERKO) mice. Impaired glucose homeostasis and increased adiposity were paralleled by diminished muscle oxidative metabolism and bioactive lipid accumulation in MERKO mice. Aberrant mitochondrial morphology, overproduction of reactive oxygen species, and impairment in basal and stress-induced mitochondrial fission dynamics, driven by imbalanced protein kinase A-regulator of calcineurin 1-calcineurin signaling through dynamin-related protein 1, tracked with reduced oxidative metabolism in MERKO muscle. Although muscle mitochondrial DNA (mtDNA) abundance was similar between the genotypes, ERα deficiency diminished mtDNA turnover by a balanced reduction in mtDNA replication and degradation. Our findings indicate the retention of dysfunctional mitochondria in MERKO muscle and implicate ERα in the preservation of mitochondrial health and insulin sensitivity as a defense against metabolic disease in women. Copyright © 2016, American Association for the Advancement of Science.

Early organ-specific mitochondrial dysfunction of jejunum and lung found in rats with experimental acute pancreatitis

PubMed Central

Mittal, Anubhav; Hickey, Anthony JR; Chai, Chau C; Loveday, Benjamin PT; Thompson, Nichola; Dare, Anna; Delahunt, Brett; Cooper, Garth JS; Windsor, John A; Phillips, Anthony RJ

2011-01-01

Introduction Multiple organ dysfunction is the main cause of death in severe acute pancreatitis. Primary mitochondrial dysfunction plays a central role in the development and progression of organ failure in critical illness. The present study investigated mitochondrial function in seven tissues during early experimental acute pancreatitis. Methods Twenty-eight male Wistar rats (463 ± 2 g; mean ± SEM) were studied. Group 1 (n = 8), saline control; Group 2 (n = 6), caerulein-induced mild acute pancreatitis; Group 3 (n = 7) sham surgical controls; and Group 4 (n = 7), taurocholate-induced severe acute pancreatitis. Animals were euthanased at 6 h from the induction of acute pancreatitis and mitochondrial function was assessed in the heart, lung, liver, kidney, pancreas, duodenum and jejunum by mitochondrial respirometry. Results Significant early mitochondrial dysfunction was present in the pancreas, lung and jejunum in both models of acute pancreatitis, however, the Heart, liver, kidney and duodenal mitochondria were unaffected. Conclusions The present study provides the first description of early organ-selective mitochondrial dysfunction in the lung and jejunum during acute pancreatitis. Research is now needed to identify the underlying pathophysiology behind the organ selective mitochondrial dysfunction, and the potential benefits of early mitochondrial-specific therapies in acute pancreatitis. PMID:21492333

Role of mitochondrial dysfunction and altered autophagy in cardiovascular aging and disease: from mechanisms to therapeutics

PubMed Central

Marzetti, Emanuele; Csiszar, Anna; Dutta, Debapriya; Balagopal, Gauthami; Calvani, Riccardo

2013-01-01

Advanced age is associated with a disproportionate prevalence of cardiovascular disease (CVD). Intrinsic alterations in the heart and the vasculature occurring over the life course render the cardiovascular system more vulnerable to various stressors in late life, ultimately favoring the development of CVD. Several lines of evidence indicate mitochondrial dysfunction as a major contributor to cardiovascular senescence. Besides being less bioenergetically efficient, damaged mitochondria also produce increased amounts of reactive oxygen species, with detrimental structural and functional consequences for the cardiovascular system. The age-related accumulation of dysfunctional mitochondrial likely results from the combination of impaired clearance of damaged organelles by autophagy and inadequate replenishment of the cellular mitochondrial pool by mitochondriogenesis. In this review, we summarize the current knowledge about relevant mechanisms and consequences of age-related mitochondrial decay and alterations in mitochondrial quality control in the cardiovascular system. The involvement of mitochondrial dysfunction in the pathogenesis of cardiovascular conditions especially prevalent in late life and the emerging connections with neurodegeneration are also illustrated. Special emphasis is placed on recent discoveries on the role played by alterations in mitochondrial dynamics (fusion and fission), mitophagy, and their interconnections in the context of age-related CVD and endothelial dysfunction. Finally, we discuss pharmacological interventions targeting mitochondrial dysfunction to delay cardiovascular aging and manage CVD. PMID:23748424

SIRT1 activation inhibits hyperglycemia-induced apoptosis by reducing oxidative stress and mitochondrial dysfunction in human endothelial cells.

PubMed

Wang, Shengqiang; Wang, Jian; Zhao, Airong; Li, Jigang

2017-09-01

Sustained hyperglycemic stimulation of vascular cells is involved in the pathogenesis of diabetes mellitus‑induced cardiovascular complications. Silent information regulator T1 (SIRT1), a mammalian sirtuin, has been previously recognized to protect endothelial cells against hyperglycemia‑induced oxidative stress. In the present study, human umbilical vein endothelial cells (HUV‑EC‑C) were treated with D‑glucose, and the levels of oxidative stress, mitochondrial dysfunction, the rate of apoptosis and SIRT1 activity were measured. The effect of manipulated SIRT1 activity on hyperglycemia‑induced oxidative stress, mitochondrial dysfunction and apoptosis was then assessed using the SIRT1 activator, resveratrol (RSV), and the SIRT1 inhibitor, sirtinol. The present study confirmed that hyperglycemia promotes oxidative stress and mitochondrial dysfunction in HUV‑EC‑C cells. The accumulation of reactive oxygen species, the swelling of mitochondria, the ratio of adenosine 5'‑diphosphate to adenosine 5'‑triphosphate and localized mitochondrial superoxide levels were all increased following D‑glucose treatment, whereas the mitochondrial membrane potential was significantly reduced by >50 mg/ml D‑glucose treatment. In addition, hyperglycemia was confirmed to induce apoptosis in HUV‑EC‑C cells. Furthermore, the results confirmed the prevention and aggravation of hyperglycemia‑induced apoptosis by RSV treatment and sirtinol treatment, via the amelioration and enhancement of oxidative stress and mitochondrial dysfunction in HUV‑EC‑C cells, respectively. In conclusion, the present study revealed that hyperglycemia promotes oxidative stress, mitochondrial dysfunction and apoptosis in HUV‑EC‑C cells, and manipulation of SIRT1 activity regulated hyperglycemia‑induced mitochondrial dysfunction and apoptosis in HUV‑EC‑C cells. The data revealed the protective effect of SIRT1 against hyperglycemia‑induced apoptosis via the alleviation of mitochondrial dysfunction and oxidative stress.

Endonuclease G is a novel determinant of cardiac hypertrophy and mitochondrial function

PubMed Central

McDermott-Roe, Chris; Ye, Junmei; Ahmed, Rizwan; Sun, Xi-Ming; Serafín, Anna; Ware, James; Bottolo, Leonardo; Muckett, Phil; Cañas, Xavier; Zhang, Jisheng; Rowe, Glenn C.; Buchan, Rachel; Lu, Han; Braithwaite, Adam; Mancini, Massimiliano; Hauton, David; Martí, Ramon; García-Arumí, Elena; Hubner, Norbert; Jacob, Howard; Serikawa, Tadao; Zidek, Vaclav; Papousek, Frantisek; Kolar, Frantisek; Cardona, Maria; Ruiz-Meana, Marisol; García-Dorado, David; Comella, Joan X; Felkin, Leanne E; Barton, Paul JR; Arany, Zoltan; Pravenec, Michal; Petretto, Enrico; Sanchis, Daniel; Cook, Stuart A.

2011-01-01

Left ventricular mass (LVM) is a highly heritable trait1 and an independent risk factor for all-cause mortality2. To date, genome-wide association studies (GWASs) have not identified the genetic factors underlying LVM variation3 and the regulatory mechanisms for blood pressure (BP)-independent cardiac hypertrophy remain poorly understood4,5. Unbiased systems-genetics approaches in the rat6,7 now provide a powerful complementary tool to GWAS and we applied integrative genomics to dissect a highly replicated, BP-independent LVM locus on rat chromosome 3p. We identified endonuclease G (Endog), previously implicated in apoptosis8 but not hypertrophy, as the gene at the locus and demonstrated loss-of-function mutation in Endog associated with increased LVM and impaired cardiac function. Inhibition of Endog in cultured cardiomyocytes resulted in an increase in cell size and hypertrophic biomarkers in the absence of pro-hypertrophic stimulation. Genome-wide network analysis unexpectedly inferred ENDOG in fundamental mitochondrial processes unrelated to apoptosis. We showed direct regulation of ENDOG by ERRα and PGC1α, master regulators of mitochondrial and cardiac function9,10,11, interaction of ENDOG with the mitochondrial genome and ENDOG-mediated regulation of mitochondrial mass. At baseline, Endog deleted mouse heart had depleted mitochondria, mitochondrial dysfunction and elevated reactive oxygen species (ROS), which was associated with enlarged and steatotic cardiomyocytes. Our studies establish further the link between mitochondrial dysfunction, ROS and heart disease and demonstrate a new role for Endog in maladaptive cardiac hypertrophy. PMID:21979051

Mitochondrial dysfunction precedes depression of AMPK/AKT signaling in insulin resistance induced by high glucose in primary cortical neurons.

PubMed

Peng, Yunhua; Liu, Jing; Shi, Le; Tang, Ying; Gao, Dan; Long, Jiangang; Liu, Jiankang

2016-06-01

Recent studies have demonstrated brain insulin signaling impairment and mitochondrial dysfunction in diabetes. Hyperinsulinemia and hyperlipidemia arising from diabetes have been linked to neuronal insulin resistance, and hyperglycemia induces peripheral sensory neuronal impairment and mitochondrial dysfunction. However, how brain glucose at diabetic conditions elicits cortical neuronal insulin signaling impairment and mitochondrial dysfunction remains unknown. In the present study, we cultured primary cortical neurons with high glucose levels and investigated the neuronal mitochondrial function and insulin response. We found that mitochondrial function was declined in presence of 10 mmol/L glucose, prior to the depression of AKT signaling in primary cortical neurons. We further demonstrated that the cerebral cortex of db/db mice exhibited both insulin resistance and loss of mitochondrial complex components. Moreover, we found that adenosine monophosphate-activated protein kinase (AMPK) inactivation is involved in high glucose-induced mitochondrial dysfunction and insulin resistance in primary cortical neurons and neuroblastoma cells, as well as in cerebral cortex of db/db mice, and all these impairments can be rescued by mitochondrial activator, resveratrol. Taken together, our results extend the finding that high glucose (≥10 mmol/L) comparable to diabetic brain extracellular glucose level leads to neuronal mitochondrial dysfunction and resultant insulin resistance, and targeting mitochondria-AMPK signaling might be a promising strategy to protect against diabetes-related neuronal impairment in central nerves system. We found that high glucose (≥10 mmol/L), comparable to diabetic brain extracellular glucose level, leads to neuronal mitochondrial dysfunction and resultant insulin resistance in an AMPK-dependent manner, and targeting mitochondria-AMPK signaling might be a promising strategy to protect against diabetes-related neuronal impairment in central nerves system. © 2016 International Society for Neurochemistry.

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.

Mitochondrial medicine for neurodegenerative diseases.

PubMed

Du, Heng; Yan, Shirley ShiDu

2010-05-01

Mitochondrial dysfunction has been reported in a wide array of neurological disorders ranging from neuromuscular to neurodegenerative diseases. Recent studies on neurodegenerative diseases have revealed that mitochondrial pathology is generally found in inherited or sporadic neurodegenerative diseases and is believed to be involved in the pathophysiological process of these diseases. Commonly seen types of mitochondrial dysfunction in neurodegenerative diseases include excessive free radical generation, lowered ATP production, mitochondrial permeability transition, mitochondrial DNA lesions, perturbed mitochondrial dynamics and apoptosis. Mitochondrial medicine as an emerging therapeutic strategy targeted to mitochondrial dysfunction in neurodegenerative diseases has been proven to be of value, though this area of research is still at in its early stage. In this article, we report on recent progress in the development of several mitochondrial therapies including antioxidants, blockade of mitochondrial permeability transition, and mitochondrial gene therapy as evidence that mitochondrial medicine has promise in the treatment of neurodegenerative diseases. 2010 Elsevier Ltd. All rights reserved.

Mitochondrial Bioenergetics and Dysfunction in Failing Heart.

PubMed

Sheeran, Freya L; Pepe, Salvatore

2017-01-01

Energy insufficiency has been recognized as a key feature of systolic heart failure. Although mitochondria have long been known to sustain myocardial work energy supply, the capacity to therapeutically target mitochondrial bioenergetics dysfunction is hampered by a complex interplay of multiple perturbations that progressively compound causing myocardial failure and collapse. Compared to non-failing human donor hearts, activity rates of complexes I and IV, nicotinamide nucleotide transhydrogenase (NADPH-transhydrogenase, Nnt) and the Krebs cycle enzymes isocitrate dehydrogenase, malate dehydrogenase and aconitase are markedly decreased in end-stage heart failure. Diminished REDOX capacity with lower total glutathione and coenzyme Q 10 levels are also a feature of chronic left ventricular failure. Decreased enzyme activities in part relate to abundant and highly specific oxidative, nitrosylative, and hyperacetylation modifications. In this brief review we highlight that energy deficiency in end-stage failing human left ventricle predominantly involves concomitantly impaired activities of key electron transport chain and Krebs cycle enzymes rather than altered expression of respective genes or proteins. Augmented oxidative modification of these enzyme subunit structures, and the formation of highly reactive secondary metabolites, implicates dysfunction due to diminished capacity for management of mitochondrial reactive oxygen species, which contribute further to progressive decreases in bioenergetic capacity and contractile function in human heart failure.

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

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

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

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

Mitochondrial dysfunction in Gulf War illness revealed by 31Phosphorus Magnetic Resonance Spectroscopy: a case-control study.

PubMed

Koslik, Hayley J; Hamilton, Gavin; Golomb, Beatrice A

2014-01-01

Approximately 1/3 of 1990-1 Gulf War veterans developed chronic multisymptom health problems. Implicated exposures bear mechanisms that adversely affect mitochondria. Symptoms emphasize fatigue, cognition and muscle (brain and muscle are aerobically demanding); with protean additional domains affected, compatible with mitochondrial impairment. Recent evidence supports treatments targeting cell bioenergetics (coenzyme10) to benefit Gulf War illness symptoms. However, no evidence has directly documented mitochondrial or bioenergetic impairment in Gulf War illness. We sought to objectively assess for mitochondrial dysfunction, examining post-exercise phosphocreatine-recovery time constant (PCr-R) using (31)Phosphorus Magnetic Resonance Spectroscopy ((31)P-MRS), in Gulf War veterans with Gulf War illness compared to matched healthy controls. PCr-R has been described as a "robust and practical" index of mitochondrial status. Case-control study from 2012-2013. Fourteen community-dwelling Gulf War veterans and matched controls from the San Diego area comprised 7 men meeting CDC and Kansas criteria for Gulf War illness, and 7 non-deployed healthy controls matched 1:1 to cases on age, sex, and ethnicity. Calf muscle phosphocreatine was evaluated by (31)P-MRS at rest, through 5 minutes of foot pedal depression exercise, and in recovery, to assess PCr-R. Paired t-tests compared cases to matched controls. PCr-R was significantly prolonged in Gulf War illness cases vs their matched controls: control values, mean ± SD, 29.0 ± 8.7 seconds; case values 46.1 ± 18.0 seconds; difference 17.1 ± 14.9 seconds; p = 0.023. PCr-R was longer for cases relative to their matched controls for all but one pair; moreover while values clustered under 31 seconds for all but one control, they exceeded 35 seconds (with a spread up to 70 seconds) for all but one case. These data provide the first direct evidence supporting mitochondrial dysfunction in Gulf War illness. Findings merit replication in a larger study and/or corroboration with additional mitochondrial assessment tools.

Giant mitochondria do not fuse and exchange their contents with normal mitochondria

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

Navratil, Marian; Terman, Alexei; Arriaga, Edgar A.

2008-01-01

Giant mitochondria accumulate within aged or diseased postmitotic cells as a consequence of insufficient autophagy, which is normally responsible for mitochondrial degradation. We report that giant mitochondria accumulating in cultured rat myoblasts due to inhibition of autophagy have low inner membrane potential and do not fuse with each other or with normal mitochondria. In addition to the low inner mitochondrial membrane potential in giant mitochondria, the quantity of the OPA1 mitochondrial fusion protein in these mitochondria was low, but the abundance of mitofusin-2 (Mfn2) remained unchanged. The combination of these factors may explain the lack of mitochondrial fusion in giantmore » mitochondria and imply that the dysfunctional giant mitochondria cannot restore their function by fusing and exchanging their contents with fully functional mitochondria. These findings have important implications for understanding the mechanisms of accumulation of age-related mitochondrial damage in postmitotic cells.« less

Mitochondrial impairment contributes to cocaine-induced cardiac dysfunction: Prevention by the targeted antioxidant MitoQ.

PubMed

Vergeade, Aurélia; Mulder, Paul; Vendeville-Dehaudt, Cathy; Estour, François; Fortin, Dominique; Ventura-Clapier, Renée; Thuillez, Christian; Monteil, Christelle

2010-09-01

The goal of this study was to assess mitochondrial function and ROS production in an experimental model of cocaine-induced cardiac dysfunction. We hypothesized that cocaine abuse may lead to altered mitochondrial function that in turn may cause left ventricular dysfunction. Seven days of cocaine administration to rats led to an increased oxygen consumption detected in cardiac fibers, specifically through complex I and complex III. ROS levels were increased, specifically in interfibrillar mitochondria. In parallel there was a decrease in ATP synthesis, whereas no difference was observed in subsarcolemmal mitochondria. This uncoupling effect on oxidative phosphorylation was not detectable after short-term exposure to cocaine, suggesting that these mitochondrial abnormalities were a late rather than a primary event in the pathological response to cocaine. MitoQ, a mitochondrial-targeted antioxidant, was shown to completely prevent these mitochondrial abnormalities as well as cardiac dysfunction characterized here by a diastolic dysfunction studied with a conductance catheter to obtain pressure-volume data. Taken together, these results extend previous studies and demonstrate that cocaine-induced cardiac dysfunction may be due to a mitochondrial defect. Copyright 2010 Elsevier Inc. All rights reserved.

Hyperoxia activates ATM independent from mitochondrial ROS and dysfunction.

PubMed

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

2015-08-01

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

The role of p66Shc deletion in age-associated arterial dysfunction and disease states.

PubMed

Camici, Giovanni G; Cosentino, Francesco; Tanner, Felix C; Lüscher, Thomas F

2008-11-01

Accumulation of oxidative stress with age is hypothesized to be the primary causative mediator of age-associated diseases. Among different tissues, aging vessels are known to accumulate oxidative damage and undergo functional impairment. Oxidative stress affects the availability and/or balance of key regulators of vascular homeostasis and favors the development of cardiovascular disease. Reactive oxygen species are generated by different intracellular molecular pathways principally located in the cytoplasm and in the mitochondria. The mitochondrial enzyme p66Shc is an adaptor protein and plays an important role as a redox enzyme implicated in mitochondrial reactive oxygen species generation and translation of oxidative signals into apoptosis. Mice lacking p66Shc-/- gene display reduced production of intracellular oxidants and a 30% prolonged life span. For this reasons, a series of studies conceived to elucidate the function of p66Shc and its possible implication in age-associated cardiovascular diseases have been carried out. Indeed, p66Shc-/- mice have been shown to be protected from age-dependent endothelial dysfunction as well as age-related risk factors such as diabetes and hypercholesterolemia. This review focuses on delineating the role of the p66Shc adaptor protein and its potential implication in the pathophysiology of aging and age-related cardiovascular disease.

Curcuminoid EF24 enhances the anti‐tumour activity of Akt inhibitor MK‐2206 through ROS‐mediated endoplasmic reticulum stress and mitochondrial dysfunction in gastric cancer

PubMed Central

Chen, Xi; Dai, Xuanxuan; Zou, Peng; Chen, Weiqian; Rajamanickam, Vinothkumar; Feng, Chen; Zhuge, Weishan; Qiu, Chenyu; Ye, Qingqing

2017-01-01

Background and Purpose Gastric cancer is one of the leading causes of morbidity and mortality worldwide. Akt is an anti‐apoptotic kinase that plays a dynamic role in cell survival and is implicated in the pathogenesis of gastric cancer. MK‐2206, the first allosteric inhibitor of Akt, is in clinical trials for a number of cancers. Although preclinical studies showed promise, clinical trials reported it had no effect when given alone at tolerated doses. The aim of our study was to delineate the effects of MK‐2206 on gastric cancer cells and explore the ability of combination treatments to enhance the anti‐tumour activity of MK‐2206. Experimental Approach SGC‐7901, BGC‐823 cells and immunodeficient mice were chosen as a model to study the treatment effects. Changes in cell viability, apoptosis and ROS, endoplasmic reticulum stress and mitochondrial dysfunction in the cells were analysed by MTT assays, ROS imaging and FACSCalibur, electron microscopy, JC‐1 staining and western blotting. Key Results MK‐2206 induced apoptotic cell death through the generation of ROS. We utilized ROS production to target gastric cancer cells by combining MK‐2206 and an ROS inducer EF24. Our in vitro and in vivo xenograft studies showed that combined treatment with MK‐2206 and EF24 synergistically induced apoptosis in gastric cancer cells and caused cell cycle arrest. These activities were mediated through ROS generation and the induction of endoplasmic reticulum stress and mitochondrial dysfunction. Conclusion and Implications Targeting ROS generation by using a combination of an Akt inhibitor and EF24 could have potential as a therapy for gastric cancer. PMID:28255993

Further Commentary on Mitochondrial Dysfunction in Autism Spectrum Disorder: Assessment and Treatment Considerations

ERIC Educational Resources Information Center

Dager, Stephen R.; Corrigan, Neva M.; Estes, Annette; Shaw, Dennis W. W.

2012-01-01

The authors respond to a recent letter (Rossignol and Frye 2011) critical of their paper, "Proton magnetic resonance spectroscopy and MRI reveal no evidence for brain mitochondrial dysfunction in children with autism spectrum disorder" (Corrigan et al. 2011). Further considerations regarding the assessment of mitochondrial dysfunction in autism…

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

PubMed Central

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

2017-01-01

Mitochondrial dysfunction has been implicated in Parkinson’s disease (PD) neuropathology. Mic60, also known as mitofilin, is a protein of the inner mitochondrial membrane and a key component of the mitochondrial contact site and cristae junction organizing system (MICOS). Mic60 is critical for maintaining mitochondrial membrane structure and function. We previously demonstrated that mitochondrial Mic60 protein is susceptible to both covalent modification and loss in abundance following exposure to dopamine quinone. In this study, we utilized neuronally-differentiated SH-SY5Y and PC12 dopaminergic cell lines to examine the effects of altered Mic60 levels on mitochondrial function and cellular vulnerability in response to PD-relevant stressors. Short hairpin RNA (shRNA)-mediated knockdown of endogenous Mic60 protein in neuronal SH-SY5Y cells significantly potentiated dopamine-induced cell death, which was rescued by co-expressing shRNA-insensitive Mic60. Conversely, in PC12 and SH-SY5Y cells, Mic60 overexpression significantly attenuated both dopamine- and rotenone-induced cell death as compared to controls. Mic60 overexpression in SH-SY5Y cells was also associated with increased mitochondrial respiration, and, following rotenone exposure, increased spare respiratory capacity. Mic60 knockdown cells exhibited suppressed respiration and, following rotenone treatment, decreased spare respiratory capacity. Mic60 overexpression also affected mitochondrial fission/fusion dynamics. PC12 cells overexpressing Mic60 exhibited increased mitochondrial interconnectivity. Further, both PC12 cells and primary rat cortical neurons overexpressing Mic60 displayed suppressed mitochondrial fission and increased mitochondrial length in neurites. These results suggest that altering levels of Mic60 in dopaminergic neuronal cells significantly affects both mitochondrial homeostasis and cellular vulnerability to the PD-relevant stressors dopamine and rotenone, carrying implications for PD pathogenesis. PMID:27001148

Pharmacological Modulation of the Mitochondrial Electron Transport Chain in Paclitaxel-Induced Painful Peripheral Neuropathy.

PubMed

Griffiths, Lisa A; Flatters, Sarah J L

2015-10-01

Paclitaxel is an effective first-line chemotherapeutic with the major dose-limiting side effect of painful neuropathy. Mitochondrial dysfunction and oxidative stress have been implicated in paclitaxel-induced painful neuropathy. Here we show the effects of pharmacological modulation of mitochondrial sites that produce reactive oxygen species using systemic rotenone (complex I inhibitor) or antimycin A (complex III inhibitor) on the maintenance and development of paclitaxel-induced mechanical hypersensitivity in adult male Sprague Dawley rats. The maximally tolerated dose (5 mg/kg) of rotenone inhibited established paclitaxel-induced mechanical hypersensitivity. However, some of these inhibitory effects coincided with decreased motor coordination; 3 mg/kg rotenone also significantly attenuated established paclitaxel-induced mechanical hypersensitivity without any motor impairment. The maximally tolerated dose (.6 mg/kg) of antimycin A reversed established paclitaxel-induced mechanical hypersensitivity without any motor impairment. Seven daily doses of systemic rotenone or antimycin A were given either after paclitaxel administration or before and during paclitaxel administration. Rotenone had no significant effect on the development of paclitaxel-induced mechanical hypersensitivity. However, antimycin A significantly inhibited the development of paclitaxel-induced mechanical hypersensitivity when given before and during paclitaxel administration but had no effect when given after paclitaxel administration. These studies provide further evidence of paclitaxel-evoked mitochondrial dysfunction in vivo, suggesting that complex III activity is instrumental in paclitaxel-induced pain. This study provides further in vivo evidence that mitochondrial dysfunction is a key contributor to the development and maintenance of chemotherapy-induced painful neuropathy. This work also indicates that selective modulation of the electron transport chain can induce antinociceptive effects in a preclinical model of paclitaxel-induced pain. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Adipose tissue mitochondrial dysfunction triggers a lipodystrophic syndrome with insulin resistance, hepatosteatosis, and cardiovascular complications

PubMed Central

Vernochet, Cecile; Damilano, Federico; Mourier, Arnaud; Bezy, Olivier; Mori, Marcelo A.; Smyth, Graham; Rosenzweig, Anthony; Larsson, Nils-Göran; Kahn, C. Ronald

2014-01-01

Mitochondrial dysfunction in adipose tissue occurs in obesity, type 2 diabetes, and some forms of lipodystrophy, but whether this dysfunction contributes to or is the result of these disorders is unknown. To investigate the physiological consequences of severe mitochondrial impairment in adipose tissue, we generated mice deficient in mitochondrial transcription factor A (TFAM) in adipocytes by using mice carrying adiponectin-Cre and TFAM floxed alleles. These adiponectin TFAM-knockout (adipo-TFAM-KO) mice had a 75–81% reduction in TFAM in the subcutaneous and intra-abdominal white adipose tissue (WAT) and interscapular brown adipose tissue (BAT), causing decreased expression and enzymatic activity of proteins in complexes I, III, and IV of the electron transport chain (ETC). This mitochondrial dysfunction led to adipocyte death and inflammation in WAT and a whitening of BAT. As a result, adipo-TFAM-KO mice were resistant to weight gain, but exhibited insulin resistance on both normal chow and high-fat diets. These lipodystrophic mice also developed hypertension, cardiac hypertrophy, and cardiac dysfunction. Thus, isolated mitochondrial dysfunction in adipose tissue can lead a syndrome of lipodystrophy with metabolic syndrome and cardiovascular complications.—Vernochet, C., Damilano, F., Mourier, A., Bezy, O., Mori, M. A., Smyth, G., Rosenzweig, A., Larsson, N.-G., Kahn, C. R. Adipose tissue mitochondrial dysfunction triggers a lipodystrophic syndrome with insulin resistance, hepatosteatosis, and cardiovascular complications. PMID:25005176

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.

Reducing Mitochondrial ROS Improves Disease-related Pathology in a Mouse Model of Ataxia-telangiectasia

PubMed Central

D'Souza, Anthony D; Parish, Ian A; Krause, Diane S; Kaech, Susan M; Shadel, Gerald S

2013-01-01

The disease ataxia-telangiectasia (A-T) has no cure and few treatment options. It is caused by mutations in the ATM kinase, which functions in the DNA-damage response and redox sensing. In addition to severe cerebellar degeneration, A-T pathology includes cancer predisposition, sterility, immune system dysfunction, and bone marrow abnormalities. These latter phenotypes are recapitulated in the ATM null (ATM−/−) mouse model of the disease. Since oxidative stress and mitochondrial dysfunction are implicated in A-T, we determined whether reducing mitochondrial reactive oxygen species (ROS) via overexpression of catalase targeted to mitochondria (mCAT) alleviates A-T–related pathology in ATM−/− mice. We found that mCAT has many beneficial effects in this context, including reduced propensity to develop thymic lymphoma, improved bone marrow hematopoiesis and macrophage differentiation in vitro, and partial rescue of memory T-cell developmental defects. Our results suggest that positive effects observed on cancer development may be linked to mCAT reducing mitochondrial ROS, lactate production, and TORC1 signaling in transforming double-positive cells, whereas beneficial effects in memory T cells appear to be TORC1-independent. Altogether, this study provides proof-of-principle that reducing mitochondrial ROS production per se may be therapeutic for the disease, which may have advantages compared with more general antioxidant strategies. PMID:23011031

Ionizing radiation accelerates Drp1-dependent mitochondrial fission, which involves delayed mitochondrial reactive oxygen species production in normal human fibroblast-like cells

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

Kobashigawa, Shinko, E-mail: kobashin@nagasaki-u.ac.jp; Suzuki, Keiji; Yamashita, Shunichi

2011-11-04

Highlights: Black-Right-Pointing-Pointer We report first time that ionizing radiation induces mitochondrial dynamic changes. Black-Right-Pointing-Pointer Radiation-induced mitochondrial fission was caused by Drp1 localization. Black-Right-Pointing-Pointer We found that radiation causes delayed ROS from mitochondria. Black-Right-Pointing-Pointer Down regulation of Drp1 rescued mitochondrial dysfunction after radiation exposure. -- Abstract: Ionizing radiation is known to increase intracellular level of reactive oxygen species (ROS) through mitochondrial dysfunction. Although it has been as a basis of radiation-induced genetic instability, the mechanism involving mitochondrial dysfunction remains unclear. Here we studied the dynamics of mitochondrial structure in normal human fibroblast like cells exposed to ionizing radiation. Delayed mitochondrial O{submore » 2}{sup {center_dot}-} production was peaked 3 days after irradiation, which was coupled with accelerated mitochondrial fission. We found that radiation exposure accumulated dynamin-related protein 1 (Drp1) to mitochondria. Knocking down of Drp1 expression prevented radiation induced acceleration of mitochondrial fission. Furthermore, knockdown of Drp1 significantly suppressed delayed production of mitochondrial O{sub 2}{sup {center_dot}-}. Since the loss of mitochondrial membrane potential, which was induced by radiation was prevented in cells knocking down of Drp1 expression, indicating that the excessive mitochondrial fission was involved in delayed mitochondrial dysfunction after irradiation.« less

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

PubMed Central

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

2015-01-01

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

Mitochondria and Mitochondrial Cascades in Alzheimer’s Disease

PubMed Central

Swerdlow, Russell H.

2017-01-01

Decades of research indicate mitochondria from Alzheimer’s disease (AD) patients differ from those of non-AD individuals. Initial studies revealed structural differences, and subsequent studies showed functional deficits. Observations of structure and function changes prompted investigators to consider the consequences, significance, and causes of AD-related mitochondrial dysfunction. Currently, extensive research argues mitochondria may mediate, drive, or contribute to a variety of AD pathologies. The perceived significance of these mitochondrial changes continues to grow, and many currently believe AD mitochondrial dysfunction represents a reasonable therapeutic target. Debate continues over the origin of AD mitochondrial changes. Some argue amyloid-β (Aβ) induces AD mitochondrial dysfunction, a view that does not challenge the amyloid cascade hypothesis and that may in fact help explain that hypothesis. Alternatively, data indicate mitochondrial dysfunction exists independent of Aβ, potentially lies upstream of Aβ deposition, and suggest a primary mitochondrial cascade hypothesis that assumes mitochondrial pathology hierarchically supersedes Aβ pathology. Mitochondria, therefore, appear at least to mediate or possibly even initiate pathologic molecular cascades in AD. This review considers studies and data that inform this area of AD research. PMID:29036828

DLP1-Dependent Mitochondrial Fragmentation Mediates 1-methyl-4-phenylpyridinium Toxicity in Neurons: Implications for Parkinson's Disease

PubMed Central

Wang, Xinglong; Su, Bo; Liu, Wanhong; He, Xiaohua; Gao, Yuan; Castellani, Rudy J.; Perry, George; Smith, Mark A.; Zhu, Xiongwei

2011-01-01

SUMMARY Selective degeneration of nigrostriatal dopaminergic neurons in Parkinson disease (PD) can be modeled by the administration of the neurotoxin 1-methyl-4-phenylpyridinium (MPP+). Since abnormal mitochondrial dynamics are increasingly implicated in the pathogenesis of PD, in this study, we investigated the effect of MPP+ on mitochondrial dynamics and assessed temporal and causal relationship with other toxic effects induced by MPP+ in neuronal cells. In SH-SY5Y cells, MPP+ causes a rapid increase in mitochondrial fragmentation followed by a second wave of increase in mitochondrial fragmentation, along with increased DLP1 expression and mitochondrial translocation. Genetic inactivation of DLP1 completely blocks MPP+-induced mitochondrial fragmentation. Notably, this approach partially rescues MPP+-induced decline in ATP levels and ATP/ADP ratio and increased [Ca2+]i and almost completely prevents increased reactive oxygen species production, loss of mitochondrial membrane potential, enhanced autophagy and cell death, suggesting that mitochondria fragmentation is an upstream event that mediates MPP+-induced toxicity. On the other hand, thiol antioxidant NAC or glutamate receptor antagonist D-AP5 also partially alleviate MPP+-induced mitochondrial fragmentation, suggesting a vicious spiral of events contributes to MPP+-induced toxicity. We further validated our findings in primary rat midbrain dopaminergic neurons that 0.5 μM MPP+ induced mitochondrial fragmentation only in TH-positive dopaminergic neurons in a similar pattern to that in SH-SY5Y cells but had no effects on these mitochondrial parameters in TH-negative neurons. Overall, these findings suggest that DLP1-dependent mitochondrial fragmentation plays a crucial role in mediating MPP+-induced mitochondria abnormalities and cellular dysfunction and may represent a novel therapeutic target for PD. PMID:21615675

Monoamine oxidase inhibition prevents mitochondrial dysfunction and apoptosis in myoblasts from patients with collagen VI myopathies.

PubMed

Sorato, E; Menazza, S; Zulian, A; Sabatelli, P; Gualandi, F; Merlini, L; Bonaldo, P; Canton, M; Bernardi, P; Di Lisa, F

2014-10-01

Although mitochondrial dysfunction and oxidative stress have been proposed to play a crucial role in several types of muscular dystrophy (MD), whether a causal link between these two alterations exists remains an open question. We have documented that mitochondrial dysfunction through opening of the permeability transition pore plays a key role in myoblasts from patients as well as in mouse models of MD, and that oxidative stress caused by monoamine oxidases (MAO) is involved in myofiber damage. In the present study we have tested whether MAO-dependent oxidative stress is a causal determinant of mitochondrial dysfunction and apoptosis in myoblasts from patients affected by collagen VI myopathies. We find that upon incubation with hydrogen peroxide or the MAO substrate tyramine myoblasts from patients upregulate MAO-B expression and display a significant rise in reactive oxygen species (ROS) levels, with concomitant mitochondrial depolarization. MAO inhibition by pargyline significantly reduced both ROS accumulation and mitochondrial dysfunction, and normalized the increased incidence of apoptosis in myoblasts from patients. Thus, MAO-dependent oxidative stress is causally related to mitochondrial dysfunction and cell death in myoblasts from patients affected by collagen VI myopathies, and inhibition of MAO should be explored as a potential treatment for these diseases. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

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

How the Wnt signaling pathway protects from neurodegeneration: the mitochondrial scenario

PubMed Central

Arrázola, Macarena S.; Silva-Alvarez, Carmen; Inestrosa, Nibaldo C.

2015-01-01

Alzheimer’s disease (AD) is the most common neurodegenerative disorder and is characterized by progressive memory loss and cognitive decline. One of the hallmarks of AD is the overproduction of amyloid-beta aggregates that range from the toxic soluble oligomer (Aβo) form to extracellular accumulations in the brain. Growing evidence indicates that mitochondrial dysfunction is a common feature of neurodegenerative diseases and is observed at an early stage in the pathogenesis of AD. Reports indicate that mitochondrial structure and function are affected by Aβo and can trigger neuronal cell death. Mitochondria are highly dynamic organelles, and the balance between their fusion and fission processes is essential for neuronal function. Interestingly, in AD, the process known as “mitochondrial dynamics” is also impaired by Aβo. On the other hand, the activation of the Wnt signaling pathway has an essential role in synaptic maintenance and neuronal functions, and its deregulation has also been implicated in AD. We have demonstrated that canonical Wnt signaling, through the Wnt3a ligand, prevents the permeabilization of mitochondrial membranes through the inhibition of the mitochondrial permeability transition pore (mPTP), induced by Aβo. In addition, we showed that non-canonical Wnt signaling, through the Wnt5a ligand, protects mitochondria from fission-fusion alterations in AD. These results suggest new approaches by which different Wnt signaling pathways protect neurons in AD, and support the idea that mitochondria have become potential therapeutic targets for the treatment of neurodegenerative disorders. Here we discuss the neuroprotective role of the canonical and non-canonical Wnt signaling pathways in AD and their differential modulation of mitochondrial processes, associated with mitochondrial dysfunction and neurodegeneration. PMID:25999816

Decreased ATP synthesis is phenotypically expressed during increased energy demand in fibroblasts containing mitochondrial tRNA mutations.

PubMed

James, A M; Sheard, P W; Wei, Y H; Murphy, M P

1999-01-01

Mutations in the tRNA genes of mitochondrial DNA (mtDNA) cause the debilitating MELAS (mitochondrial, myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and MERRF (myoclonic epilepsy and ragged-red fibres) syndromes. These mtDNA mutations affect respiratory chain function, apparently without decreasing cellular ATP concentration [Moudy et al. (1995) PNAS, 92, 729-733]. To address this issue, we investigated the role of mitochondrial ATP synthesis in fibroblasts from MELAS and MERRF patients. The maximum rate of mitochondrial ATP synthesis was decreased by 60-88%, as a consequence of the decrease in the proton electrochemical potential gradient of MELAS and MERRF mitochondria. However, in quiescent fibroblasts neither ATP concentration or the ATP/ADP ratio was affected by the lowered rate of ATP synthesis. We hypothesized that the low ATP demand of quiescent fibroblasts masked the mitochondrial ATP synthesis defect and that this defect might become apparent during higher ATP use. To test this we simulated high energy demand by titrating cells with gramicidin, an ionophore that stimulates ATP hydrolysis by the plasma membrane Na+/K+-ATPase. We found a threshold gramicidin concentration in control cells at which both the ATP/ADP ratio and the plasma membrane potential decreased dramatically, due to ATP demand by the Na+/K+-ATPase outstripping mitochondrial ATP synthesis. In MELAS and MERRF fibroblasts the corresponding threshold concentrations of gramicidin were 2-20-fold lower than those for control cells. This is the first demonstration that cells containing mtDNA mutations are particularly sensitive to increased ATP demand and this has several implications for how mitochondrial dysfunction contributes to disease pathophysiology. In particular, the increased susceptibility to plasma membrane depolarization will render neurons with dysfunctional mitochondria susceptible to excitotoxic cell death.

Epoxyeicosatrienoic acids pretreatment improves amyloid β-induced mitochondrial dysfunction in cultured rat hippocampal astrocytes.

PubMed

Sarkar, Pallabi; Zaja, Ivan; Bienengraeber, Martin; Rarick, Kevin R; Terashvili, Maia; Canfield, Scott; Falck, John R; Harder, David R

2014-02-15

Amyloid-β (Aβ) has long been implicated as a causative protein in Alzheimer's disease. Cellular Aβ accumulation is toxic and causes mitochondrial dysfunction, which precedes clinical symptoms of Alzheimer's disease pathology. In the present study, we explored the possible use of epoxyeicosatrienoic acids (EETs), epoxide metabolites of arachidonic acid, as therapeutic target against Aβ-induced mitochondrial impairment using cultured neonatal hippocampal astrocytes. Inhibition of endogenous EET production by a selective epoxygenase inhibitor, MS-PPOH, caused a greater reduction in mitochondrial membrane potential in the presence of Aβ (1, 10 μM) exposure versus absence of Aβ. MS-PPOH preincubation also aggravated Aβ-induced mitochondrial fragmentation. Preincubation of the cells with either 14,15- or 11,12-EET prevented this mitochondrial depolarization and fragmentation. EET pretreatment also further improved the reduction observed in mitochondrial oxygen consumption in the presence of Aβ. Preincubation of the cells with EETs significantly improved cellular respiration under basal condition and in the presence of the protonophore, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP). The uncoupling of ATP synthase from the electron transfer chain that occurred in Aβ-treated cells was also prevented by preincubation with EETs. Lastly, cellular reactive oxygen species production, a hallmark of Aβ toxicity, also showed significant reduction in the presence of EETs. We have previously shown that Aβ reduces EET synthesis in rat brain homogenates and cultured hippocampal astrocytes and neurons (Sarkar P, Narayanan J, Harder DR. Differential effect of amyloid beta on the cytochrome P450 epoxygenase activity in rat brain. Neuroscience 194: 241-249, 2011). We conclude that reduction of endogenous EETs may be one of the mechanisms through which Aβ inflicts toxicity and thus supplementing the cells with exogenous EETs improves mitochondrial dynamics and prevents metabolic impairment.

Biomarkers and Brain Mechanisms of Gulf War Illness

DTIC Science & Technology

2017-09-01

serve as biomarkers of the disorder. 15. SUBJECT TERMS Gulf War illness, neuroinflammation, oxidative stress , mitochondrial dysfunction, magnetic...Oxidative Stress , Mitochondrial Dysfunction; Magnetic Resonance Imaging, Positron Emission Tomography Page | 5 Subtask 2: Develop complementary or...30 Major Task 3: To conduct 1H and 31P MRS studies for assessment of oxidative stress and mitochondrial dysfunction in vivo. Assess cerebral blood

Proton Magnetic Resonance Spectroscopy and MRI Reveal No Evidence for Brain Mitochondrial Dysfunction in Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Corrigan, Neva M.; Shaw, Dennis. W. W.; Richards, Todd L.; Estes, Annette M.; Friedman, Seth D.; Petropoulos, Helen; Artru, Alan A.; Dager, Stephen R.

2012-01-01

Brain mitochondrial dysfunction has been proposed as an etiologic factor in autism spectrum disorder (ASD). Proton magnetic resonance spectroscopic imaging ([superscript 1]HMRS) and MRI were used to assess for evidence of brain mitochondrial dysfunction in longitudinal samples of children with ASD or developmental delay (DD), and cross-sectionally…

Adipose tissue mitochondrial dysfunction triggers a lipodystrophic syndrome with insulin resistance, hepatosteatosis, and cardiovascular complications.

PubMed

Vernochet, Cecile; Damilano, Federico; Mourier, Arnaud; Bezy, Olivier; Mori, Marcelo A; Smyth, Graham; Rosenzweig, Anthony; Larsson, Nils-Göran; Kahn, C Ronald

2014-10-01

Mitochondrial dysfunction in adipose tissue occurs in obesity, type 2 diabetes, and some forms of lipodystrophy, but whether this dysfunction contributes to or is the result of these disorders is unknown. To investigate the physiological consequences of severe mitochondrial impairment in adipose tissue, we generated mice deficient in mitochondrial transcription factor A (TFAM) in adipocytes by using mice carrying adiponectin-Cre and TFAM floxed alleles. These adiponectin TFAM-knockout (adipo-TFAM-KO) mice had a 75-81% reduction in TFAM in the subcutaneous and intra-abdominal white adipose tissue (WAT) and interscapular brown adipose tissue (BAT), causing decreased expression and enzymatic activity of proteins in complexes I, III, and IV of the electron transport chain (ETC). This mitochondrial dysfunction led to adipocyte death and inflammation in WAT and a whitening of BAT. As a result, adipo-TFAM-KO mice were resistant to weight gain, but exhibited insulin resistance on both normal chow and high-fat diets. These lipodystrophic mice also developed hypertension, cardiac hypertrophy, and cardiac dysfunction. Thus, isolated mitochondrial dysfunction in adipose tissue can lead a syndrome of lipodystrophy with metabolic syndrome and cardiovascular complications. © FASEB.

Emerging Mitochondrial Therapeutic Targets in Optic Neuropathies.

PubMed

Lopez Sanchez, M I G; Crowston, J G; Mackey, D A; Trounce, I A

2016-09-01

Optic neuropathies are an important cause of blindness worldwide. The study of the most common inherited mitochondrial optic neuropathies, Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (ADOA) has highlighted a fundamental role for mitochondrial function in the survival of the affected neuron-the retinal ganglion cell. A picture is now emerging that links mitochondrial dysfunction to optic nerve disease and other neurodegenerative processes. Insights gained from the peculiar susceptibility of retinal ganglion cells to mitochondrial dysfunction are likely to inform therapeutic development for glaucoma and other common neurodegenerative diseases of aging. Despite it being a fast-evolving field of research, a lack of access to human ocular tissues and limited animal models of mitochondrial disease have prevented direct retinal ganglion cell experimentation and delayed the development of efficient therapeutic strategies to prevent vision loss. Currently, there are no approved treatments for mitochondrial disease, including optic neuropathies caused by primary or secondary mitochondrial dysfunction. Recent advances in eye research have provided important insights into the molecular mechanisms that mediate pathogenesis, and new therapeutic strategies including gene correction approaches are currently being investigated. Here, we review the general principles of mitochondrial biology relevant to retinal ganglion cell function and provide an overview of the major optic neuropathies with mitochondrial involvement, LHON and ADOA, whilst highlighting the emerging link between mitochondrial dysfunction and glaucoma. The pharmacological strategies currently being trialed to improve mitochondrial dysfunction in these optic neuropathies are discussed in addition to emerging therapeutic approaches to preserve retinal ganglion cell function. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed

Guo, Rui; Ren, Jun

2010-01-18

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

Loss of thymidine kinase 2 alters neuronal bioenergetics and leads to neurodegeneration

PubMed Central

Bartesaghi, Stefano; Betts-Henderson, Joanne; Cain, Kelvin; Dinsdale, David; Zhou, Xiaoshan; Karlsson, Anna; Salomoni, Paolo; Nicotera, Pierluigi

2010-01-01

Mutations of thymidine kinase 2 (TK2), an essential component of the mitochondrial nucleotide salvage pathway, can give rise to mitochondrial DNA (mtDNA) depletion syndromes (MDS). These clinically heterogeneous disorders are characterized by severe reduction in mtDNA copy number in affected tissues and are associated with progressive myopathy, hepatopathy and/or encephalopathy, depending in part on the underlying nuclear genetic defect. Mutations of TK2 have previously been associated with an isolated myopathic form of MDS (OMIM 609560). However, more recently, neurological phenotypes have been demonstrated in patients carrying TK2 mutations, thus suggesting that loss of TK2 results in neuronal dysfunction. Here, we directly address the role of TK2 in neuronal homeostasis using a knockout mouse model. We demonstrate that in vivo loss of TK2 activity leads to a severe ataxic phenotype, accompanied by reduced mtDNA copy number and decreased steady-state levels of electron transport chain proteins in the brain. In TK2-deficient cerebellar neurons, these abnormalities are associated with impaired mitochondrial bioenergetic function, aberrant mitochondrial ultrastructure and degeneration of selected neuronal types. Overall, our findings demonstrate that TK2 deficiency leads to neuronal dysfunction in vivo, and have important implications for understanding the mechanisms of neurological impairment in MDS. PMID:20123860

Loss of thymidine kinase 2 alters neuronal bioenergetics and leads to neurodegeneration.

PubMed

Bartesaghi, Stefano; Betts-Henderson, Joanne; Cain, Kelvin; Dinsdale, David; Zhou, Xiaoshan; Karlsson, Anna; Salomoni, Paolo; Nicotera, Pierluigi

2010-05-01

Mutations of thymidine kinase 2 (TK2), an essential component of the mitochondrial nucleotide salvage pathway, can give rise to mitochondrial DNA (mtDNA) depletion syndromes (MDS). These clinically heterogeneous disorders are characterized by severe reduction in mtDNA copy number in affected tissues and are associated with progressive myopathy, hepatopathy and/or encephalopathy, depending in part on the underlying nuclear genetic defect. Mutations of TK2 have previously been associated with an isolated myopathic form of MDS (OMIM 609560). However, more recently, neurological phenotypes have been demonstrated in patients carrying TK2 mutations, thus suggesting that loss of TK2 results in neuronal dysfunction. Here, we directly address the role of TK2 in neuronal homeostasis using a knockout mouse model. We demonstrate that in vivo loss of TK2 activity leads to a severe ataxic phenotype, accompanied by reduced mtDNA copy number and decreased steady-state levels of electron transport chain proteins in the brain. In TK2-deficient cerebellar neurons, these abnormalities are associated with impaired mitochondrial bioenergetic function, aberrant mitochondrial ultrastructure and degeneration of selected neuronal types. Overall, our findings demonstrate that TK2 deficiency leads to neuronal dysfunction in vivo, and have important implications for understanding the mechanisms of neurological impairment in MDS.

The Role of PGC-1α in Vascular Regulation: Implications for Atherosclerosis

PubMed Central

Kadlec, Andrew O.; Chabowski, Dawid S.; Ait-Aissa, Karima; Gutterman, David D.

2016-01-01

Mitochondrial dysfunction results in high levels of oxidative stress and mitochondrial damage, leading to disruption of endothelial homeostasis. Recent discoveries have clarified several pathways whereby mitochondrial dysregulation contributes to endothelial dysfunction and vascular disease burden. One such pathway centers around PGC-1α, a transcriptional coactivator linked to mitochondrial biogenesis and antioxidant defense, among other functions. Although primarily investigated for its therapeutic potential in obesity and skeletal muscle differentiation, the ability of PGC-1α to alter a multitude of cellular functions has sparked interest in its role in the vasculature. Within this context, recent studies demonstrate that PGC-1α plays a key role in endothelial cell and smooth muscle cell regulation through effects on oxidative stress, apoptosis, inflammation, and cell proliferation. The ability of PGC-1α to impact these parameters is relevant to vascular disease progression, particularly in relation to atherosclerosis. Upregulation of PGC-1α can prevent the development of, and even encourage regression of, atherosclerotic lesions. Therefore, PGC-1α is poised to serve as a promising target in vascular disease. This review details recent findings related to PGC-1α in vascular regulation, regulation of PGC-1α itself, the role of PGC-1α in atherosclerosis, and therapies that target this key protein. PMID:27312223

Mitochondrial permeability transition pore: a promising target for the treatment of Parkinson's disease.

PubMed

Rasheed, Md Zeeshan; Tabassum, Heena; Parvez, Suhel

2017-01-01

Among the neurodegenerative diseases (ND), Parkinson's disease affects 6.3 million people worldwide characterized by the progressive loss of dopaminergic neurons in substantia nigra. The mitochondrial permeability transition pore (mtPTP) is a non-selective voltage-dependent mitochondrial channel whose opening modifies the permeability properties of the mitochondrial inner membrane. It is recognized as a potent pharmacological target for diseases associated with mitochondrial dysfunction and excessive cell death including ND such as Parkinson's disease (PD). Imbalance in Ca 2+ concentration, change in mitochondrial membrane potential, overproduction of reactive oxygen species (ROS), or mutation in mitochondrial genome has been implicated in the pathophysiology of the opening of the mtPTP. Different proteins are released by permeability transition including cytochrome c which is responsible for apoptosis. This review aims to discuss the importance of PTP in the pathophysiology of PD and puts together different positive as well as negative aspects of drugs such as pramipexole, ropinirole, minocyclin, rasagilin, and safinamide which act as a blocker or modifier for mtPTP. Some of them may be detrimental in their neuroprotective nature.

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).

Mesenchymal stem cells alleviate oxidative stress-induced mitochondrial dysfunction in the airways.

PubMed

Li, Xiang; Michaeloudes, Charalambos; Zhang, Yuelin; Wiegman, Coen H; Adcock, Ian M; Lian, Qizhou; Mak, Judith C W; Bhavsar, Pankaj K; Chung, Kian Fan

2018-05-01

Oxidative stress-induced mitochondrial dysfunction can contribute to inflammation and remodeling in patients with chronic obstructive pulmonary disease (COPD). Mesenchymal stem cells protect against lung damage in animal models of COPD. It is unknown whether these effects occur through attenuating mitochondrial dysfunction in airway cells. We sought to examine the effect of induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSCs) on oxidative stress-induce mitochondrial dysfunction in human airway smooth muscle cells (ASMCs) in vitro and in mouse lungs in vivo. ASMCs were cocultured with iPSC-MSCs in the presence of cigarette smoke medium (CSM), and mitochondrial reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨm), and apoptosis were measured. Conditioned medium from iPSC-MSCs and transwell cocultures were used to detect any paracrine effects. The effect of systemic injection of iPSC-MSCs on airway inflammation and hyperresponsiveness in ozone-exposed mice was also investigated. Coculture of iPSC-MSCs with ASMCs attenuated CSM-induced mitochondrial ROS, apoptosis, and ΔΨm loss in ASMCs. iPSC-MSC-conditioned medium or transwell cocultures with iPSC-MSCs reduced CSM-induced mitochondrial ROS but not ΔΨm or apoptosis in ASMCs. Mitochondrial transfer from iPSC-MSCs to ASMCs was observed after direct coculture and was enhanced by CSM. iPSC-MSCs attenuated ozone-induced mitochondrial dysfunction, airway hyperresponsiveness, and inflammation in mouse lungs. iPSC-MSCs offered protection against oxidative stress-induced mitochondrial dysfunction in human ASMCs and in mouse lungs while reducing airway inflammation and hyperresponsiveness. These effects are, at least in part, dependent on cell-cell contact, which allows for mitochondrial transfer, and paracrine regulation. Therefore iPSC-MSCs show promise as a therapy for oxidative stress-dependent lung diseases, such as COPD. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Hyperhomocysteinemia associated skeletal muscle weakness involves mitochondrial dysfunction and epigenetic modifications

PubMed Central

Veeranki, Sudhakar; Winchester, Lee J; Tyagi, Suresh C

2015-01-01

HHcy has been implicated in elderly frailty, but the underlying mechanisms are poorly understood. Using C57 and CBS+/- mice and C2C12 cell line, we investigated mechanisms behind HHcy induced skeletal muscle weakness and fatigability. Possible alterations in metabolic capacity (levels of LDH, CS, MM-CK and COX-IV), in structural proteins (levels of dystrophin) and in mitochondrial function (ATP production) were examined. An exercise regimen was employed to reverse HHcy induced changes. CBS+/- mice exhibited more fatigability, and generated less contraction force. No significant changes in muscle morphology were observed. However, there is corresponding reduction in large muscle fiber number in CBS+/- mice. Excess fatigability was not due to changes in key enzymes involved in metabolism, but was due to reduced ATP levels. A marginal reduction in dystrophin levels along with a decrease in mitochondrial transcription factor A (mtTFA) were observed. There was also an increase in the mir-31, and mir-494 quantities that were implicated in dystrophin and mtTFA regulation respectively. The molecular changes elevated during HHcy, with the exception of dystrophin levels, were reversed after exercise. In addition, amount of NRF-1, one of the transcriptional regulators of mtTFA, was significantly decreased. Furthermore, there was enhancement in mir-494 levels and a concomitant decline in mtTFA protein quantity in homocysteine treated cells. These changes in C2C12 cells were also accompanied by an increase in DNMT3a and DNMT3b proteins and global DNA methylation levels. Together, these results suggest that HHcy plays a causal role in enhanced fatigability through mitochondrial dysfunction which involves epigenetic changes. PMID:25615794

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

Binukumar, BK; Gupta, Nidhi; Bal, Amanjit

Numerous epidemiological studies have shown an association between pesticide exposure and increased risk of developing Parkinson's diseases. Oxidative stress generated as a result of mitochondrial dysfunction has been implicated as an important factor in the etiology of Parkinson's disease. Previously, we reported that chronic dichlorvos exposure causes mitochondrial impairments and nigrostriatal neuronal death in rats. The present study was designed to test whether Coenzyme Q{sub 10} (CoQ{sub 10}) administration has any neuroprotective effect against dichlorvos mediated nigrostriatal neuronal death, {alpha}-synuclein aggregation, and motor dysfunction. Male albino rats were administered dichlorvos by subcutaneous injection at a dose of 2.5 mg/kg bodymore » weight over a period of 12 weeks. Results obtained there after showed that dichlorvos exposure leads to enhanced mitochondrial ROS production, {alpha}-synuclein aggregation, decreased dopamine and its metabolite levels resulting in nigrostriatal neurodegeneration. Pretreatment by Coenzyme Q{sub 10} (4.5 mg/kg ip for 12 weeks) to dichlorvos treated animals significantly attenuated the extent of nigrostriatal neuronal damage, in terms of decreased ROS production, increased dopamine and its metabolite levels, and restoration of motor dysfunction when compared to dichlorvos treated animals. Thus, the present study shows that Coenzyme Q{sub 10} administration may attenuate dichlorvos induced nigrostriatal neurodegeneration, {alpha}-synuclein aggregation and motor dysfunction by virtue of its antioxidant action. - Highlights: > CoQ{sub 10} administration attenuates dichlorvos induced nigrostriatal neurodegenaration. > CoQ{sub 10} pre treatment leads to preservation of TH-IR neurons. > CoQ{sub 10} may decrease oxidative damage and {alpha}-synuclin aggregation. > CoQ{sub 10} treatment enhances motor function and protects rats from catalepsy.« less

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.

Mitochondrial Calcium Dysregulation Contributes to Dendrite Degeneration Mediated by PD/LBD-Associated LRRK2 Mutants.

PubMed

Verma, Manish; Callio, Jason; Otero, P Anthony; Sekler, Israel; Wills, Zachary P; Chu, Charleen T

2017-11-15

Mutations in leucine-rich repeat kinase 2 (LRRK2) contribute to development of late-onset familial Parkinson's disease (PD), with clinical features of motor and cognitive dysfunction indistinguishable from sporadic PD. Calcium dysregulation plays an important role in PD pathogenesis, but the mechanisms of neurodegeneration remain unclear. Recent reports indicate enhanced excitatory neurotransmission in cortical neurons expressing mutant LRRK2, which occurs before the well-characterized phenotype of dendritic shortening. As mitochondria play a major role in the rapid buffering of cytosolic calcium, we hypothesized that altered mitochondrial calcium handling contributes to dendritic retraction elicited by the LRRK2-G2019S and -R1441C mutations. In primary mouse cortical neurons, we observed increased depolarization-induced mitochondrial calcium uptake. We found that expression of mutant LRRK2 elicited transcriptional upregulation of the mitochondrial calcium uniporter (MCU) and the mitochondrial calcium uptake 1 protein (MICU1) with no change in levels of the mitochondrial calcium antiporter NCLX. Elevated MCU and MICU1 were also observed in LRRK2-mutated patient fibroblasts, along with increased mitochondrial calcium uptake, and in postmortem brains of sporadic PD/PDD patients of both sexes. Transcriptional upregulation of MCU and MICU1 was caused by activation of the ERK1/2 (MAPK3/1) pathway. Inhibiting ERK1/2 conferred protection against mutant LRRK2-induced neurite shortening. Pharmacological inhibitors or RNAi knockdown of MCU attenuated mitochondrial calcium uptake and dendritic/neuritic shortening elicited by mutant LRRK2, whereas expression of a constitutively active mutant of NCLX that enhances calcium export from mitochondria was neuroprotective. These data suggest that an increased susceptibility to mitochondrial calcium dysregulation contributes to dendritic injury in mutant LRRK2 pathogenesis. SIGNIFICANCE STATEMENT Cognitive dysfunction and dementia are common features of Parkinson's disease (PD), causing significant disability. Mutations in LRRK2 represent the most common known genetic cause of PD. We found that PD-linked LRRK2 mutations increased dendritic and mitochondrial calcium uptake in cortical neurons and familial PD patient fibroblasts, accompanied by increased expression of the mitochondrial calcium transporter MCU. Blocking the ERK1/2-dependent upregulation of MCU conferred protection against mutant LRRK2-elicited dendrite shortening, as did inhibiting MCU-mediated calcium import. Conversely, stimulating the export of calcium from mitochondria was also neuroprotective. These results implicate increased susceptibility to mitochondrial calcium overload in LRRK2-driven neurodegeneration, and suggest possible interventions that may slow the progression of cognitive dysfunction in PD. Copyright © 2017 the authors 0270-6474/17/3711152-15$15.00/0.

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

PubMed

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

2016-02-01

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

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

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

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

2014-08-15

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

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

PubMed

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

2014-09-15

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

Mitochondrial-associated metabolic disorders: foundations, pathologies and recent progress

PubMed Central

2013-01-01

Research in the last decade has revolutionized the way in which we view mitochondria. Mitochondria are no longer viewed solely as cellular powerhouses; rather, mitochondria are now understood to be vibrant, mobile structures, constantly undergoing fusion and fission, and engaging in intimate interactions with other cellular compartments and structures. Findings have implicated mitochondria in a wide variety of cellular processes and molecular interactions, such as calcium buffering, lipid flux, and intracellular signaling. As such, it does not come as a surprise that an increasing number of human pathologies have been associated with functional defects in mitochondria. The difficulty in understanding and treating human pathologies caused by mitochondrial dysfunction arises from the complex relationships between mitochondria and other cellular processes, as well as the genetic background of such diseases. This review attempts to provide a summary of the background knowledge and recent developments in mitochondrial processes relating to mitochondrial-associated metabolic diseases arising from defects or deficiencies in mitochondrial function, as well as insights into current and future avenues for investigation. PMID:24499129

Utility of Periodontal exploration in patients with Fibromyalgia

PubMed Central

Santos-García, Rocío; Sánchez-Domínguez, Benito; Cordero, Mario D.; Rios-Santos, José V.; Jaramillo-Santos, María R.; Climent, Mariano H.

2012-01-01

Objetive: Fibromyalgia (FM) is a chronic pain syndrome with unknown etiology, which affects predominantly women. Mitochondrial alteration could have a role in the pathophysilogical mechanisms of inflammatory conditions as FM and periodontitis. The aim of the present study was assay the relationship between both diseases and mitochondrial dysfunction. Patient and Methods: We study the presence of periodontitis in twelve patients diagnosed of FM and mitochondrial dysfunction described. The diagnosis of FM was established according to ACR criteria and clinical symptoms were evaluated using the Fibromyalgia Impact Questionnaire (FIQ) and Beck Depression Inventory (BDI). Results: Only one patients of twelve included and agreed to participate in the study were diagnosed with periodontitis. Conclusions: Pending studies with larger numbers of patients, we can conclude that mitochondrial dysfunction in FM is a itself event not related with periodontitis. Periodontitis could be considered a exclusion criterion in all studies about mitochondrial dysfunction in patients. Key words:Peridontitis, fibromyalgia, mitocondrial dysfunction, oxidative stress. PMID:24558523

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

PubMed

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

2015-09-01

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

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.

Kidney-targeted inhibition of protein kinase C-α ameliorates nephrotoxic nephritis with restoration of mitochondrial dysfunction.

PubMed

Kvirkvelia, Nino; McMenamin, Malgorzata; Warren, Marie; Jadeja, Ravirajsinh N; Kodeboyina, Sai Karthik; Sharma, Ashok; Zhi, Wenbo; O'Connor, Paul M; Raju, Raghavan; Lucas, Rudolf; Madaio, Michael P

2018-05-04

To investigate the role of protein kinase C-α (PKC-α) in glomerulonephritis, the capacity of PKC-α inhibition to reverse the course of established nephrotoxic nephritis (NTN) was evaluated. Nephritis was induced by a single injection of nephrotoxic serum and after its onset, a PKC-α inhibitor was administered either systemically or by targeted glomerular delivery. By day seven, all mice with NTN had severe nephritis, whereas mice that received PKC-α inhibitors in either form had minimal evidence of disease. To further understand the underlying mechanism, label-free shotgun proteomic analysis of the kidney cortexes were performed, using quantitative mass spectrometry. Ingenuity pathway analysis revealed 157 differentially expressed proteins and mitochondrial dysfunction as the most modulated pathway. Functional protein groups most affected by NTN were mitochondrial proteins associated with respiratory processes. These proteins were down-regulated in the mice with NTN, while their expression was restored with PKC-α inhibition. This suggests a role for proteins that regulate oxidative phosphorylation in recovery. In cultured glomerular endothelial cells, nephrotoxic serum caused a decrease in mitochondrial respiration and membrane potential, mitochondrial morphologic changes and an increase in glycolytic lactic acid production; all normalized by PKC-α inhibition. Thus, PKC-α has a critical role in NTN progression, and the results implicate mitochondrial processes through restoring oxidative phosphorylation, as an essential mechanism underlying recovery. Importantly, our study provides additional support for targeted therapy to glomeruli to reverse the course of progressive disease. Copyright © 2018 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

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

PubMed

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

2016-04-01

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

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

PubMed Central

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

2016-01-01

Objective Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an enhanced risk for liver and cardiovascular diseases and mortality. NAFLD can progress from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH). However, the mechanisms predisposing to this progression remain undefined. Notably, hepatic mitochondrial dysfunction is a common finding in patients with NASH. Due to a lack of appropriate experimental animal models, it has not been evaluated whether this mitochondrial dysfunction plays a causative role for the development of NASH. Methods To determine the effect of a well-defined mitochondrial dysfunction on liver physiology at baseline and during dietary challenge, C57BL/6J-mtFVB/N mice were employed. This conplastic inbred strain has been previously reported to exhibit decreased mitochondrial respiration likely linked to a non-synonymous gene variation (nt7778 G/T) of the mitochondrial ATP synthase protein 8 (mt-ATP8). Results At baseline conditions, C57BL/6J-mtFVB/N mice displayed hepatic mitochondrial dysfunction characterized by decreased ATP production and increased formation of reactive oxygen species (ROS). Moreover, genes affecting lipid metabolism were differentially expressed, hepatic triglyceride and cholesterol levels were changed in these animals, and various acyl-carnitines were altered, pointing towards an impaired mitochondrial carnitine shuttle. However, over a period of twelve months, no spontaneous hepatic steatosis or inflammation was observed. On the other hand, upon dietary challenge with either a methionine and choline deficient diet or a western-style diet, C57BL/6J-mtFVB/N mice developed aggravated steatohepatitis as characterized by lipid accumulation, ballooning of hepatocytes and infiltration of immune cells. Conclusions We observed distinct metabolic alterations in mice with a mitochondrial polymorphism associated hepatic mitochondrial dysfunction. However, a second hit, such as dietary stress, was required to cause hepatic steatosis and inflammation. This study suggests a causative role of hepatic mitochondrial dysfunction in the development of experimental NASH. PMID:27069868

Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) Aggregation Causes Mitochondrial Dysfunction during Oxidative Stress-induced Cell Death*

PubMed Central

Itakura, Masanori; Kubo, Takeya; Kaneshige, Akihiro; Harada, Naoki; Izawa, Takeshi; Azuma, Yasu-Taka; Kuwamura, Mitsuru; Yamaji, Ryouichi; Takeuchi, Tadayoshi

2017-01-01

Glycolytic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional protein that also mediates cell death under oxidative stress. We reported previously that the active-site cysteine (Cys-152) of GAPDH plays an essential role in oxidative stress-induced aggregation of GAPDH associated with cell death, and a C152A-GAPDH mutant rescues nitric oxide (NO)-induced cell death by interfering with the aggregation of wild type (WT)-GAPDH. However, the detailed mechanism underlying GAPDH aggregate-induced cell death remains elusive. Here we report that NO-induced GAPDH aggregation specifically causes mitochondrial dysfunction. First, we observed a correlation between NO-induced GAPDH aggregation and mitochondrial dysfunction, when GAPDH aggregation occurred at mitochondria in SH-SY5Y cells. In isolated mitochondria, aggregates of WT-GAPDH directly induced mitochondrial swelling and depolarization, whereas mixtures containing aggregates of C152A-GAPDH reduced mitochondrial dysfunction. Additionally, treatment with cyclosporin A improved WT-GAPDH aggregate-induced swelling and depolarization. In doxycycline-inducible SH-SY5Y cells, overexpression of WT-GAPDH augmented NO-induced mitochondrial dysfunction and increased mitochondrial GAPDH aggregation, whereas induced overexpression of C152A-GAPDH significantly suppressed mitochondrial impairment. Further, NO-induced cytochrome c release into the cytosol and nuclear translocation of apoptosis-inducing factor from mitochondria were both augmented in cells overexpressing WT-GAPDH but ameliorated in C152A-GAPDH-overexpressing cells. Interestingly, GAPDH aggregates induced necrotic cell death via a permeability transition pore (PTP) opening. The expression of either WT- or C152A-GAPDH did not affect other cell death pathways associated with protein aggregation, such as proteasome inhibition, gene expression induced by endoplasmic reticulum stress, or autophagy. Collectively, these results suggest that NO-induced GAPDH aggregation specifically induces mitochondrial dysfunction via PTP opening, leading to cell death. PMID:28167533

CypD-mPTP axis regulates mitochondrial functions contributing to osteogenic dysfunction of MC3T3-E1 cells in inflammation.

PubMed

Gan, Xueqi; Zhang, Ling; Liu, Beilei; Zhu, Zhuoli; He, Yuting; Chen, Junsheng; Zhu, Junfei; Yu, Haiyang

2018-04-20

Bone is a dynamic organ, the bone-forming osteoblasts and bone-resorbing osteoclasts form the physiological basis of bone remodeling process. During pathological process of numerous inflammatory diseases, these two aspects are uncoupled and the balance is usually tipped in favor of bone destruction. Evidence suggests that the inflammatory destruction of bone is mainly attributed to oxidative stress and is closely related to mitochondrial dysfunction. The mechanisms underlying osteogenic dysfunction in inflammation still need further investigation. Reactive oxygen species (ROS) is associated with mitochondrial dysfunction and cellular damage. Here, we reported an unexplored role of cyclophilin D (CypD), the major modulator of mitochondrial permeability transition pore (mPTP), and the CypD-mPTP axis in inflammation-induced mitochondrial dysfunction and bone damage. And the protective effects of knocking down CypD by siRNA interference or the addition of cyclosporin A (CsA), an inhibitor of CypD, were evidenced by rescued mitochondrial function and osteogenic function of osteoblast under tumor necrosis factor-α (TNF-α) treatment. These findings provide new insights into the role of CypD-mPTP-dependent mitochondrial pathway in the inflammatory bone injury. The protective effect of CsA or other moleculars affecting the mPTP formation may hold promise as a potential novel therapeutic strategy for inflammation-induced bone damage via mitochondrial pathways.

Mitofusin2 mutations disrupt axonal mitochondrial positioning and promote axon degeneration

PubMed Central

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

2012-01-01

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

Hyperuricemia induces endothelial dysfunction via mitochondrial Na+/Ca2+ exchanger-mediated mitochondrial calcium overload.

PubMed

Hong, Quan; Qi, Ka; Feng, Zhe; Huang, Zhiyong; Cui, Shaoyuan; Wang, Liyuan; Fu, Bo; Ding, Rui; Yang, Jurong; Chen, Xiangmei; Wu, Di

2012-05-01

Uric acid (UA) has proven to be a causal agent in endothelial dysfunction in which ROS production plays an important role. Calcium overload in mitochondria can promote the mitochondrial production of ROS. We hypothesize that calcium transduction in mitochondria contributes to UA-induced endothelial dysfunction. We first demonstrated that high concentrations of UA cause endothelial dysfunction, marked by a reduction in eNOS protein expression and NO release in vitro. We further found that a high concentration of UA increased levels of [Ca2+]mito, total intracellular ROS, H2O2, and mitochondrial O2·-, and Δψmito but not the [Ca2+]cyt level. When the mitochondrial calcium channels NCXmito and MCU were blocked by CGP-37157 and Ru360, respectively, the UA-induced increases in the levels of [Ca2+]mito and total intracellular ROS were significantly reduced. Mitochondrial levels of O2·- and Δψmito were reduced by inhibition of NCXmito but not of MCU. Moreover, inhibition of NCXmito, but not of MCU, blocked the UA-induced reductions in eNOS protein expression and NO release. The increased generation of mitochondrial O2·- induced by a high concentration of UA is triggered by mitochondrial calcium overload and ultimately leads to endothelial dysfunction. In this process, the activation of NCXmito is the major cause of the influx of calcium into mitochondria. Our results provide a new pathophysiological mechanism for UA-induced endothelial dysfunction and may offer a new therapeutic target for clinicians. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mitochondrial-targeted antioxidants represent a promising approach for prevention of cisplatin-induced nephropathy

PubMed Central

Mukhopadhyay, Partha; Horváth, Béla; Zsengellér, Zsuzsanna; Zielonka, Jacek; Tanchian, Galin; Holovac, Eileen; Kechrid, Malek; Patel, Vivek; Stillman, Isaac E.; Parikh, Samir M.; Joseph, Joy; Kalyanaraman, Balaraman; Pacher, Pál

2011-01-01

Cisplatin is a widely used anti-neoplastic agent; however, its major limitation is the development of dose-dependent nephrotoxicity whose precise mechanisms are poorly understood. Here we show that mitochondrial dysfunction is not only a feature of cisplatin nephrotoxicity, but that targeted delivery of superoxide dismutase mimetics to mitochondria largely prevents the renal effects of cisplatin. Cisplatin induced renal oxidative stress, deterioration of mitochondrial structure and function, an intense inflammatory response, histopathological injury, and renal dysfunction. A single systemic dose of mitochondrially-targeted antioxidants, MitoQ or Mito-CP, dose-dependently prevented cisplatin-induced renal dysfunction. Mito-CP also prevented mitochondrial injury and dysfunction, renal inflammation, and tubular injury and apoptosis. Despite being broadly renoprotective against cisplatin, Mito-CP did not diminish cisplatin’s anti-neoplastic effect in a human bladder cancer cell line. Our results highlight the central role of mitochondrially generated oxidants in the pathogenesis of cisplatin nephrotoxicity. Since similar compounds appear to be safe in humans, mitochondrially-targeted antioxidants may represent a novel therapeutic approach against cisplatin nephrotoxicity. PMID:22120494

Knockdown of TWIST1 enhances arsenic trioxide- and ionizing radiation-induced cell death in lung cancer cells by promoting mitochondrial dysfunction

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

Seo, Sung-Keum; Kim, Jae-Hee; Choi, Ha-Na

Highlights: • Knockdown of TWIST1 enhanced ATO- and IR-induced cell death in NSCLCs. • Intracellular ROS levels were increased in cells treated with TWIST1 siRNA. • TWIST1 siRNA induced MMP loss and mitochondrial fragmentation. • TWIST1 siRNA upregulated the fission-related proteins FIS1 and DRP1. - Abstract: TWIST1 is implicated in the process of epithelial mesenchymal transition, metastasis, stemness, and drug resistance in cancer cells, and therefore is a potential target for cancer therapy. In the present study, we found that knockdown of TWIST1 by small interfering RNA (siRNA) enhanced arsenic trioxide (ATO)- and ionizing radiation (IR)-induced cell death in non-small-cellmore » lung cancer cells. Interestingly, intracellular reactive oxygen species levels were increased in cells treated with TWIST1 siRNA and further increased by co-treatment with ATO or IR. Pretreatment of lung cancer cells with the antioxidant N-acetyl-cysteine markedly suppressed the cell death induced by combined treatment with TWIST1 siRNA and ATO or IR. Moreover, treatment of cells with TWIST1 siRNA induced mitochondrial membrane depolarization and significantly increased mitochondrial fragmentation (fission) and upregulated the fission-related proteins FIS1 and DRP1. Collectively, our results demonstrate that siRNA-mediated TWIST1 knockdown induces mitochondrial dysfunction and enhances IR- and ATO-induced cell death in lung cancer cells.« less

Critical contribution of RIPK1 mediated mitochondrial dysfunction and oxidative stress to compression-induced rat nucleus pulposus cells necroptosis and apoptosis.

PubMed

Chen, Songfeng; Lv, Xiao; Hu, Binwu; Zhao, Lei; Li, Shuai; Li, Zhiliang; Qing, Xiangcheng; Liu, Hongjian; Xu, Jianzhong; Shao, Zengwu

2018-04-28

The aim of this study was to investigate whether RIPK1 mediated mitochondrial dysfunction and oxidative stress contributed to compression-induced nucleus pulposus (NP) cells necroptosis and apoptosis, together with the interplay relationship between necroptosis and apoptosis in vitro. Rat NP cells underwent various periods of 1.0 MPa compression. To determine whether compression affected mitochondrial function, we evaluated the mitochondrial membrane potential, mitochondrial permeability transition pore (mPTP), mitochondrial ultrastructure and ATP content. Oxidative stress-related indicators reactive oxygen species, superoxide dismutase and malondialdehyde were also assessed. To verify the relevance between oxidative stress and necroptosis together with apoptosis, RIPK1 inhibitor necrostatin-1(Nec-1), mPTP inhibitor cyclosporine A (CsA), antioxidants and small interfering RNA technology were utilized. The results established that compression elicited a time-dependent mitochondrial dysfunction and elevated oxidative stress. Nec-1 and CsA restored mitochondrial function and reduced oxidative stress, which corresponded to decreased necroptosis and apoptosis. CsA down-regulated mitochondrial cyclophilin D expression, but had little effects on RIPK1 expression and pRIPK1 activation. Additionally, we found that Nec-1 largely blocked apoptosis; whereas, the apoptosis inhibitor Z-VAD-FMK increased RIPK1 expression and pRIPK1 activation, and coordinated regulation of necroptosis and apoptosis enabled NP cells survival more efficiently. In contrast to Nec-1, SiRIPK1 exacerbated mitochondrial dysfunction and oxidative stress. In summary, RIPK1-mediated mitochondrial dysfunction and oxidative stress play a crucial role in NP cells necroptosis and apoptosis during compression injury. The synergistic regulation of necroptosis and apoptosis may exert more beneficial effects on NP cells survival, and ultimately delaying or even retarding intervertebral disc degeneration.

Mitochondrial Cardiomyopathy Caused by Elevated Reactive Oxygen Species and Impaired Cardiomyocyte Proliferation.

PubMed

Zhang, Donghui; Li, Yifei; Heims-Waldron, Danielle; Bezzerides, Vassilios; Guatimosim, Silvia; Guo, Yuxuan; Gu, Fei; Zhou, Pingzhu; Lin, Zhiqiang; Ma, Qing; Liu, Jianming; Wang, Da-Zhi; Pu, William T

2018-01-05

Although mitochondrial diseases often cause abnormal myocardial development, the mechanisms by which mitochondria influence heart growth and function are poorly understood. To investigate these disease mechanisms, we studied a genetic model of mitochondrial dysfunction caused by inactivation of Tfam (transcription factor A, mitochondrial), a nuclear-encoded gene that is essential for mitochondrial gene transcription and mitochondrial DNA replication. Tfam inactivation by Nkx2.5 Cre caused mitochondrial dysfunction and embryonic lethal myocardial hypoplasia. Tfam inactivation was accompanied by elevated production of reactive oxygen species (ROS) and reduced cardiomyocyte proliferation. Mosaic embryonic Tfam inactivation confirmed that the block to cardiomyocyte proliferation was cell autonomous. Transcriptional profiling by RNA-seq demonstrated the activation of the DNA damage pathway. Pharmacological inhibition of ROS or the DNA damage response pathway restored cardiomyocyte proliferation in cultured fetal cardiomyocytes. Neonatal Tfam inactivation by AAV9-cTnT-Cre caused progressive, lethal dilated cardiomyopathy. Remarkably, postnatal Tfam inactivation and disruption of mitochondrial function did not impair cardiomyocyte maturation. Rather, it elevated ROS production, activated the DNA damage response pathway, and decreased cardiomyocyte proliferation. We identified a transient window during the first postnatal week when inhibition of ROS or the DNA damage response pathway ameliorated the detrimental effect of Tfam inactivation. Mitochondrial dysfunction caused by Tfam inactivation induced ROS production, activated the DNA damage response, and caused cardiomyocyte cell cycle arrest, ultimately resulting in lethal cardiomyopathy. Normal mitochondrial function was not required for cardiomyocyte maturation. Pharmacological inhibition of ROS or DNA damage response pathways is a potential strategy to prevent cardiac dysfunction caused by some forms of mitochondrial dysfunction. © 2017 American Heart Association, Inc.

Control mechanisms in mitochondrial oxidative phosphorylation☆

PubMed Central

Hroudová, Jana; Fišar, Zdeněk

2013-01-01

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

Control mechanisms in mitochondrial oxidative phosphorylation.

PubMed

Hroudová, Jana; Fišar, Zdeněk

2013-02-05

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

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

PubMed Central

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

2015-01-01

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

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

Telomeres and Mitochondria in the Aging Heart

PubMed Central

Moslehi, Javid; DePinho, Ronald A.; Sahin, Ergün

2013-01-01

Studies in humans and in mice have highlighted the importance of short telomeres and impaired mitochondrial function in driving age-related functional decline in the heart. Although telomere and mitochondrial dysfunction have been viewed mainly in isolation, recent studies in telomerase-deficient mice have provided evidence for an intimate link between these two processes. Telomere dysfunction induces a profound p53-dependent repression of the master regulators of mitochondrial biogenesis and function, peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and PGC-1β in the heart, which leads to bioenergetic compromise due to impaired oxidative phosphorylation and ATP generation. This telomere-p53-PGC mitochondrial/metabolic axis integrates many factors linked to heart aging including increased DNA damage, p53 activation, mitochondrial, and metabolic dysfunction and provides a molecular basis of how dysfunctional telomeres can compromise cardiomyocytes and stem cell compartments in the heart to precipitate cardiac aging. PMID:22539756

Clinical, pathological and functional characterization of riboflavin-responsive neuropathy

PubMed Central

Manole, Andreea; Jaunmuktane, Zane; Hargreaves, Iain; Ludtmann, Marthe H R; Salpietro, Vincenzo; Bello, Oscar D; Pope, Simon; Pandraud, Amelie; Horga, Alejandro; Scalco, Renata S; Li, Abi; Ashokkumar, Balasubramaniem; Lourenço, Charles M; Heales, Simon; Horvath, Rita; Chinnery, Patrick F; Toro, Camilo; Singleton, Andrew B; Jacques, Thomas S; Abramov, Andrey Y; Muntoni, Francesco; Hanna, Michael G; Reilly, Mary M; Revesz, Tamas; Kullmann, Dimitri M

2017-01-01

Abstract Brown-Vialetto-Van Laere syndrome represents a phenotypic spectrum of motor, sensory, and cranial nerve neuropathy, often with ataxia, optic atrophy and respiratory problems leading to ventilator-dependence. Loss-of-function mutations in two riboflavin transporter genes, SLC52A2 and SLC52A3, have recently been linked to Brown-Vialetto-Van Laere syndrome. However, the genetic frequency, neuropathology and downstream consequences of riboflavin transporter mutations are unclear. By screening a large cohort of 132 patients with early-onset severe sensory, motor and cranial nerve neuropathy we confirmed the strong genetic link between riboflavin transporter mutations and Brown-Vialetto-Van Laere syndrome, identifying 22 pathogenic mutations in SLC52A2 and SLC52A3, 14 of which were novel. Brain and spinal cord neuropathological examination of two cases with SLC52A3 mutations showed classical symmetrical brainstem lesions resembling pathology seen in mitochondrial disease, including severe neuronal loss in the lower cranial nerve nuclei, anterior horns and corresponding nerves, atrophy of the spinothalamic and spinocerebellar tracts and posterior column–medial lemniscus pathways. Mitochondrial dysfunction has previously been implicated in an array of neurodegenerative disorders. Since riboflavin metabolites are critical components of the mitochondrial electron transport chain, we hypothesized that reduced riboflavin transport would result in impaired mitochondrial activity, and confirmed this using in vitro and in vivo models. Electron transport chain complex I and complex II activity were decreased in SLC52A2 patient fibroblasts, while global knockdown of the single Drosophila melanogaster riboflavin transporter homologue revealed reduced levels of riboflavin, downstream metabolites, and electron transport chain complex I activity. This in turn led to abnormal mitochondrial membrane potential, respiratory chain activity and morphology. Riboflavin transporter knockdown in Drosophila also resulted in severely impaired locomotor activity and reduced lifespan, mirroring patient pathology, and these phenotypes could be partially rescued using a novel esterified derivative of riboflavin. Our findings expand the genetic, clinical and neuropathological features of Brown-Vialetto-Van Laere syndrome, implicate mitochondrial dysfunction as a downstream consequence of riboflavin transporter gene defects, and validate riboflavin esters as a potential therapeutic strategy. PMID:29053833

Clinical, pathological and functional characterization of riboflavin-responsive neuropathy.

PubMed

Manole, Andreea; Jaunmuktane, Zane; Hargreaves, Iain; Ludtmann, Marthe H R; Salpietro, Vincenzo; Bello, Oscar D; Pope, Simon; Pandraud, Amelie; Horga, Alejandro; Scalco, Renata S; Li, Abi; Ashokkumar, Balasubramaniem; Lourenço, Charles M; Heales, Simon; Horvath, Rita; Chinnery, Patrick F; Toro, Camilo; Singleton, Andrew B; Jacques, Thomas S; Abramov, Andrey Y; Muntoni, Francesco; Hanna, Michael G; Reilly, Mary M; Revesz, Tamas; Kullmann, Dimitri M; Jepson, James E C; Houlden, Henry

2017-11-01

Brown-Vialetto-Van Laere syndrome represents a phenotypic spectrum of motor, sensory, and cranial nerve neuropathy, often with ataxia, optic atrophy and respiratory problems leading to ventilator-dependence. Loss-of-function mutations in two riboflavin transporter genes, SLC52A2 and SLC52A3, have recently been linked to Brown-Vialetto-Van Laere syndrome. However, the genetic frequency, neuropathology and downstream consequences of riboflavin transporter mutations are unclear. By screening a large cohort of 132 patients with early-onset severe sensory, motor and cranial nerve neuropathy we confirmed the strong genetic link between riboflavin transporter mutations and Brown-Vialetto-Van Laere syndrome, identifying 22 pathogenic mutations in SLC52A2 and SLC52A3, 14 of which were novel. Brain and spinal cord neuropathological examination of two cases with SLC52A3 mutations showed classical symmetrical brainstem lesions resembling pathology seen in mitochondrial disease, including severe neuronal loss in the lower cranial nerve nuclei, anterior horns and corresponding nerves, atrophy of the spinothalamic and spinocerebellar tracts and posterior column-medial lemniscus pathways. Mitochondrial dysfunction has previously been implicated in an array of neurodegenerative disorders. Since riboflavin metabolites are critical components of the mitochondrial electron transport chain, we hypothesized that reduced riboflavin transport would result in impaired mitochondrial activity, and confirmed this using in vitro and in vivo models. Electron transport chain complex I and complex II activity were decreased in SLC52A2 patient fibroblasts, while global knockdown of the single Drosophila melanogaster riboflavin transporter homologue revealed reduced levels of riboflavin, downstream metabolites, and electron transport chain complex I activity. This in turn led to abnormal mitochondrial membrane potential, respiratory chain activity and morphology. Riboflavin transporter knockdown in Drosophila also resulted in severely impaired locomotor activity and reduced lifespan, mirroring patient pathology, and these phenotypes could be partially rescued using a novel esterified derivative of riboflavin. Our findings expand the genetic, clinical and neuropathological features of Brown-Vialetto-Van Laere syndrome, implicate mitochondrial dysfunction as a downstream consequence of riboflavin transporter gene defects, and validate riboflavin esters as a potential therapeutic strategy. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain.

β-Lapachone attenuates mitochondrial dysfunction in MELAS cybrid cells.

PubMed

Jeong, Moon Hee; Kim, Jin Hwan; Seo, Kang-Sik; Kwak, Tae Hwan; Park, Woo Jin

2014-11-21

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochondrial disease caused by mutations in the mitochondrial genome. This study investigated the efficacy of β-lapachone (β-lap), a natural quinone compound, in rescuing mitochondrial dysfunction in MELAS cybrid cells. β-Lap significantly restored energy production and mitochondrial membrane potential as well as normalized the elevated ROS level in MELAS cybrid cells. Additionally, β-lap reduced lactic acidosis and restored glucose uptake in the MELAS cybrid cells. Finally, β-lap activated Sirt1 by increasing the intracellular NAD(+)/NADH ratio, which was accompanied by increased mtDNA content. Two other quinone compounds (idebenone and CoQ10) that have rescued mitochondrial dysfunction in previous studies of MELAS cybrid cells had a minimal effect in the current study. Taken together, these results demonstrated that β-lap may provide a novel therapeutic modality for the treatment of MELAS. Copyright © 2014 Elsevier Inc. All rights reserved.

Mitochondrial disorders: Challenges in diagnosis & treatment

PubMed Central

Khan, Nahid Akhtar; Govindaraj, Periyasamy; Meena, Angamuthu Kannan; Thangaraj, Kumarasamy

2015-01-01

Mitochondrial dysfunctions are known to be responsible for a number of heterogenous clinical presentations with multi-systemic involvement. Impaired oxidative phosphorylation leading to a decrease in cellular energy (ATP) production is the most important cause underlying these disorders. Despite significant progress made in the field of mitochondrial medicine during the last two decades, the molecular mechanisms underlying these disorders are not fully understood. Since the identification of first mitochondrial DNA (mtDNA) mutation in 1988, there has been an exponential rise in the identification of mtDNA and nuclear DNA mutations that are responsible for mitochondrial dysfunction and disease. Genetic complexity together with ever widening clinical spectrum associated with mitochondrial dysfunction poses a major challenge in diagnosis and treatment. Effective therapy has remained elusive till date and is mostly efficient in relieving symptoms. In this review, we discuss the important clinical and genetic features of mitochondrials disorders with special emphasis on diagnosis and treatment. PMID:25857492

Mitochondria and ageing: role in heart, skeletal muscle and adipose tissue

PubMed Central

Boengler, Kerstin; Kosiol, Maik; Mayr, Manuel; Schulz, Rainer

2017-01-01

Abstract Age is the most important risk factor for most diseases. Mitochondria play a central role in bioenergetics and metabolism. In addition, several lines of evidence indicate the impact of mitochondria in lifespan determination and ageing. The best‐known hypothesis to explain ageing is the free radical theory, which proposes that cells, organs, and organisms age because they accumulate reactive oxygen species (ROS) damage over time. Mitochondria play a central role as the principle source of intracellular ROS, which are mainly formed at the level of complex I and III of the respiratory chain. Dysfunctional mitochondria generating less ATP have been observed in various aged organs. Mitochondrial dysfunction comprises different features including reduced mitochondrial content, altered mitochondrial morphology, reduced activity of the complexes of the electron transport chain, opening of the mitochondrial permeability transition pore, and increased ROS formation. Furthermore, abnormalities in mitochondrial quality control or defects in mitochondrial dynamics have also been linked to senescence. Among the tissues affected by mitochondrial dysfunction are those with a high‐energy demand and thus high mitochondrial content. Therefore, the present review focuses on the impact of mitochondria in the ageing process of heart and skeletal muscle. In this article, we review different aspects of mitochondrial dysfunction and discuss potential therapeutic strategies to improve mitochondrial function. Finally, novel aspects of adipose tissue biology and their involvement in the ageing process are discussed. PMID:28432755

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

PubMed Central

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

2017-01-01

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

Mechanisms of Mitochondrial Dysfunction in Autism

DTIC Science & Technology

2012-07-01

area code) Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Mechanisms of Mitochondrial Dysfunction in Autism Dr. John Shoffner...before we will be able to draw meaningful conclusions from this study. Autism , functional MRI, mitochondria, mitochondrial disease 15 Table of Contents...mitochondrial defects in autism are not known, it is hypothesized that significant numbers of individuals with autism and autistic spectrum disorders

Protective effects of phosphodiesterase-1 (PDE1) and ATP sensitive potassium (KATP) channel modulators against 3-nitropropionic acid induced behavioral and biochemical toxicities in experimental Huntington׳s disease.

PubMed

Gupta, Surbhi; Sharma, Bhupesh

2014-06-05

Huntington׳s disease (HD), a devastating neurodegenerative disorder, is characterized by weight loss, impairment of motor function, cognitive dysfunction, neuropsychiatric disturbances and striatal damage. Phosphodiesterase-1 (PDE1) has been implicated in various neurological diseases. Mitochondrial potassium channels in the brain take part in neuroprotection. This study has been structured to investigate the role of vinpocetine, a selective PDE1 inhibitor as well as nicorandil, selective ATP sensitive potassium (KATP) channel opener in 3-nitropropionic acid (3-NP) induced HD symptoms in rats. Systemic administration of 3-NP significantly, reduced body weight, impaired locomotion, grip strength and impaired cognition. 3-NP elicited marked oxidative stress in the brain (enhanced malondialdehyde-MDA, reduced glutathione-GSH content, superoxide dismutase-SOD and catalase-CAT), elevated brain acetylcholinesterase activity and inflammation (myeloperoxidase-MPO), with marked nitrosative stress (nitrite/nitrate) in the brain. 3-NP has also induced mitochondrial dysfunction (impaired mitochondrial NADH dehydrogenase-complex I, succinate dehydrogenase-complex II and cytochrome oxidase-complex IV) activities in the striatum of the rat. Tetrabenazine was used as a positive control. Treatment with vinpocetine, nicorandil and tetrabenazine ameliorated 3-NP induced reduction in body weight, impaired locomotion, grip strength and impaired cognition. Treatment with these drugs reduced brain striatum oxidative (MDA, GSH, SOD and CAT) and nitrosative (nitrite/nitrate) stress, acetylcholinesterase activity, inflammation and mitochondrial dysfunctions. These results indicate that vinpocetine, a selective PDE1 inhibitor and nicorandil, a KATP channel opener have attenuated 3-NP induced experimental HD. Hence, pharmacological modulation of PDE1 as well as KATP channels may be considered as potential research targets for mitigation of HD. Copyright © 2014 Elsevier B.V. All rights reserved.

Transcription factors CEP-1/p53 and CEH-23 collaborate with AAK-2/AMPK to modulate longevity in Caenorhabditis elegans.

PubMed

Chang, Hsin-Wen; Pisano, Steve; Chaturbedi, Amaresh; Chen, Jennifer; Gordon, Sarah; Baruah, Aiswarya; Lee, Siu Sylvia

2017-08-01

A decline in mitochondrial electron transport chain (ETC) function has long been implicated in aging and various diseases. Recently, moderate mitochondrial ETC dysfunction has been found to prolong lifespan in diverse organisms, suggesting a conserved and complex role of mitochondria in longevity determination. Several nuclear transcription factors have been demonstrated to mediate the lifespan extension effect associated with partial impairment of the ETC, suggesting that compensatory transcriptional response to be crucial. In this study, we showed that the transcription factors CEP-1/p53 and CEH-23 act through a similar mechanism to modulate longevity in response to defective ETC in Caenorhabditis elegans. Genomewide gene expression profiling comparison revealed a new link between these two transcription factors and AAK-2/AMP kinase (AMPK) signaling. Further functional analyses suggested that CEP-1/p53 and CEH-23 act downstream of AAK-2/AMPK signaling and CRTC-1 transcriptional coactivator to promote stress resistance and lifespan. As AAK-2, CEP-1, and CEH-23 are all highly conserved, our findings likely provide important insights for understanding the organismal adaptive response to mitochondrial dysfunction in diverse organisms and will be relevant to aging and pathologies with a mitochondrial etiology in human. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Avocado Oil Improves Mitochondrial Function and Decreases Oxidative Stress in Brain of Diabetic Rats.

PubMed

Ortiz-Avila, Omar; Esquivel-Martínez, Mauricio; Olmos-Orizaba, Berenice Eridani; Saavedra-Molina, Alfredo; Rodriguez-Orozco, Alain R; Cortés-Rojo, Christian

2015-01-01

Diabetic encephalopathy is a diabetic complication related to the metabolic alterations featuring diabetes. Diabetes is characterized by increased lipid peroxidation, altered glutathione redox status, exacerbated levels of ROS, and mitochondrial dysfunction. Although the pathophysiology of diabetic encephalopathy remains to be clarified, oxidative stress and mitochondrial dysfunction play a crucial role in the pathogenesis of chronic diabetic complications. Taking this into consideration, the aim of this work was to evaluate the effects of 90-day avocado oil intake in brain mitochondrial function and oxidative status in streptozotocin-induced diabetic rats (STZ rats). Avocado oil improves brain mitochondrial function in diabetic rats preventing impairment of mitochondrial respiration and mitochondrial membrane potential (ΔΨ m ), besides increasing complex III activity. Avocado oil also decreased ROS levels and lipid peroxidation and improved the GSH/GSSG ratio as well. These results demonstrate that avocado oil supplementation prevents brain mitochondrial dysfunction induced by diabetes in association with decreased oxidative stress.

Mitochondrial Dynamics in Mitochondrial Diseases

PubMed Central

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

2016-01-01

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

Mitochondrial Dysfunction and Its Relationship with mTOR Signaling and Oxidative Damage in Autism Spectrum Disorders.

PubMed

Yui, Kunio; Sato, Atsushi; Imataka, George

2015-01-01

Mitochondria are organelles that play a central role in processes related to cellular viability, such as energy production, cell growth, cell death via apoptosis, and metabolism of reactive oxygen species (ROS). We can observe behavioral abnormalities relevant to autism spectrum disorders (ASDs) and their recovery mediated by the mTOR inhibitor rapamycin in mouse models. In Tsc2(+/-) mice, the transcription of multiple genes involved in mTOR signaling is enhanced, suggesting a crucial role of dysregulated mTOR signaling in the ASD model. This review proposes that the mTOR inhibitor may be useful for the pharmacological treatment of ASD. This review offers novel insights into mitochondrial dysfunction and the related impaired glutathione synthesis and lower detoxification capacity. Firstly, children with ASD and concomitant mitochondrial dysfunction have been reported to manifest clinical symptoms similar to those of mitochondrial disorders, and it therefore shows that the clinical manifestations of ASD with a concomitant diagnosis of mitochondrial dysfunction are likely due to these mitochondrial disorders. Secondly, the adenosine triphosphate (ATP) production/oxygen consumption pathway may be a potential candidate for preventing mitochondrial dysfunction due to oxidative stress, and disruption of ATP synthesis alone may be related to impaired glutathione synthesis. Finally, a decrease in total antioxidant capacity may account for ASD children who show core social and behavioral impairments without neurological and somatic symptoms.

Alzheimer, mitochondria and gender.

PubMed

Grimm, Amandine; Mensah-Nyagan, Ayikoe Guy; Eckert, Anne

2016-08-01

Epidemiological studies revealed that two-thirds of Alzheimer's disease (AD) patients are women and the drop of sex steroid hormones after the menopause has been proposed to be one risk factor in AD. Similarly, the decrease of circulating testosterone levels with aging may also increase the risk of AD in men. Studies attest the neuroprotective effects of sex hormones in animal models of AD, but clinical trial data remain controversial. Here, we discuss the implication of mitochondria in gender differences observed in AD patients and animal models of AD. We summarize the role of mitochondria in aging and AD, pointing to the potential correlation between the loss of sex hormones and changes in the brain redox status. We discuss the protective effects of the sex hormones, estradiol, progesterone and testosterone with a specific focus on mitochondrial dysfunction in AD. The understanding of pathological processes linking the loss of sex hormones with mitochondrial dysfunction and mechanisms that initiate the disease onset may open new avenues for the development of gender-specific therapeutic approaches. Copyright © 2016. Published by Elsevier Ltd.

Mitochondrial NDUFS3 regulates the ROS-mediated onset of metabolic switch in transformed cells

PubMed Central

Suhane, Sonal; Kanzaki, Hirotaka; Arumugaswami, Vaithilingaraja; Murali, Ramachandran; Ramanujan, V. Krishnan

2013-01-01

Summary Aerobic glycolysis in transformed cells is an unique metabolic phenotype characterized by a hyperactivated glycolytic pathway even in the presence of oxygen. It is not clear if the onset of aerobic glycolysis is regulated by mitochondrial dysfunction and, if so, what the metabolic windows of opportunity available to control this metabolic switch (mitochondrial to glycolytic) landscape are in transformed cells. Here we report a genetically-defined model system based on the gene-silencing of a mitochondrial complex I subunit, NDUFS3, where we demonstrate the onset of metabolic switch in isogenic human embryonic kidney cells by differential expression of NDUFS3. By means of extensive metabolic characterization, we demonstrate that NDUFS3 gene silencing systematically introduces mitochondrial dysfunction thereby leading to the onset of aerobic glycolysis in a manner dependent on NDUFS3 protein levels. Furthermore, we show that the sustained imbalance in free radical dynamics is a necessary condition to sustain the observed metabolic switch in cell lines with the most severe NDUFS3 suppression. Together, our data reveal a novel role for mitochondrial complex I subunit NDUFS3 in regulating the degree of mitochondrial dysfunction in living cells, thereby setting a “metabolic threshold” for the observation of aerobic glycolysis phenotype within the confines of mitochondrial dysfunction. PMID:23519235

Low molecular weight guluronate prevents TNF-α-induced oxidative damage and mitochondrial dysfunction in C2C12 skeletal muscle cells.

PubMed

Dun, Yun-lou; Zhou, Xiao-lin; Guan, Hua-shi; Yu, Guang-li; Li, Chun-xia; Hu, Ting; Zhao, Xia; Cheng, Xiao-lei; He, Xiao-xi; Hao, Jie-jie

2015-09-01

Muscle wasting is associated with a variety of chronic or inflammatory disorders. Evidence suggests that inflammatory cytokines play a vital role in muscle inflammatory pathology and this may result in oxidative damage and mitochondrial dysfunction in skeletal muscle. In our study, we used microwave degradation to prepare a water-soluble low molecular weight guluronate (LMG) of 3000 Da from Fucus vesiculosus obtained from Canada, the Atlantic Ocean. We demonstrated the structural characteristics, using HPLC, FTIR and NMR of LMG and investigated its effects on oxidative damage and mitochondrial dysfunction in C2C12 skeletal muscle cells induced by tumor necrosis factor alpha (TNF-α), a cell inflammatory cytokine. The results indicated that LMG could alleviate mitochondrial reactive oxygen species (ROS) production, increase the activities of antioxidant enzymes (GSH and SOD), promote mitochondrial membrane potential (MMP) and upregulate the expression of mitochondrial respiratory chain protein in TNF-α-induced C2C12 cells. LMG supplement also increased the mitochondrial DNA copy number and mitochondrial biogenesis related genes in TNF-α-induced C2C12 cells. LMG may exert these protective effects through the nuclear factor kappa B (NF-κB) signaling pathway. These suggest that LMG is capable of protecting TNF-α-induced C2C12 cells against oxidative damage and mitochondrial dysfunction.

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

PubMed

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

2015-06-01

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

Compartmentalized Regulation of Parkin-Mediated Mitochondrial Quality Control in the Drosophila Nervous System In Vivo.

PubMed

Sung, Hyun; Tandarich, Lauren C; Nguyen, Kenny; Hollenbeck, Peter J

2016-07-13

In neurons, the normal distribution and selective removal of mitochondria are considered essential for maintaining the functions of the large asymmetric cell and its diverse compartments. Parkin, a E3 ubiquitin ligase associated with familial Parkinson's disease, has been implicated in mitochondrial dynamics and removal in cells including neurons. However, it is not clear how Parkin functions in mitochondrial turnover in vivo, or whether Parkin-dependent events of the mitochondrial life cycle occur in all neuronal compartments. Here, using the live Drosophila nervous system, we investigated the involvement of Parkin in mitochondrial dynamics, distribution, morphology, and removal. Contrary to our expectations, we found that Parkin-deficient animals do not accumulate senescent mitochondria in their motor axons or neuromuscular junctions; instead, they contain far fewer axonal mitochondria, and these displayed normal motility behavior, morphology, and metabolic state. However, the loss of Parkin did produce abnormal tubular and reticular mitochondria restricted to the motor cell bodies. In addition, in contrast to drug-treated, immortalized cells in vitro, mature motor neurons rarely displayed Parkin-dependent mitophagy. These data indicate that the cell body is the focus of Parkin-dependent mitochondrial quality control in neurons, and argue that a selection process allows only healthy mitochondria to pass from cell bodies to axons, perhaps to limit the impact of mitochondrial dysfunction. Parkin has been proposed to police mitochondrial fidelity by binding to dysfunctional mitochondria via PTEN (phosphatase and tensin homolog)-induced putative kinase 1 (PINK1) and targeting them for autophagic degradation. However, it is unknown whether and how the PINK1/Parkin pathway regulates the mitochondrial life cycle in neurons in vivo Using Drosophila motor neurons, we show that parkin disruption generates an abnormal mitochondrial network in cell bodies in vivo and reduces the number of axonal mitochondria without producing any defects in their axonal transport, morphology, or metabolic state. Furthermore, while cultured neurons display Parkin-dependent axonal mitophagy, we find this is vanishingly rare in vivo under normal physiological conditions. Thus, both the spatial distribution and mechanism of mitochondrial quality control in vivo differ substantially from those observed in vitro. Copyright © 2016 the authors 0270-6474/16/367375-17$15.00/0.

Compartmentalized Regulation of Parkin-Mediated Mitochondrial Quality Control in the Drosophila Nervous System In Vivo

PubMed Central

Sung, Hyun; Tandarich, Lauren C.; Nguyen, Kenny

2016-01-01

In neurons, the normal distribution and selective removal of mitochondria are considered essential for maintaining the functions of the large asymmetric cell and its diverse compartments. Parkin, a E3 ubiquitin ligase associated with familial Parkinson's disease, has been implicated in mitochondrial dynamics and removal in cells including neurons. However, it is not clear how Parkin functions in mitochondrial turnover in vivo, or whether Parkin-dependent events of the mitochondrial life cycle occur in all neuronal compartments. Here, using the live Drosophila nervous system, we investigated the involvement of Parkin in mitochondrial dynamics, distribution, morphology, and removal. Contrary to our expectations, we found that Parkin-deficient animals do not accumulate senescent mitochondria in their motor axons or neuromuscular junctions; instead, they contain far fewer axonal mitochondria, and these displayed normal motility behavior, morphology, and metabolic state. However, the loss of Parkin did produce abnormal tubular and reticular mitochondria restricted to the motor cell bodies. In addition, in contrast to drug-treated, immortalized cells in vitro, mature motor neurons rarely displayed Parkin-dependent mitophagy. These data indicate that the cell body is the focus of Parkin-dependent mitochondrial quality control in neurons, and argue that a selection process allows only healthy mitochondria to pass from cell bodies to axons, perhaps to limit the impact of mitochondrial dysfunction. SIGNIFICANCE STATEMENT Parkin has been proposed to police mitochondrial fidelity by binding to dysfunctional mitochondria via PTEN (phosphatase and tensin homolog)-induced putative kinase 1 (PINK1) and targeting them for autophagic degradation. However, it is unknown whether and how the PINK1/Parkin pathway regulates the mitochondrial life cycle in neurons in vivo. Using Drosophila motor neurons, we show that parkin disruption generates an abnormal mitochondrial network in cell bodies in vivo and reduces the number of axonal mitochondria without producing any defects in their axonal transport, morphology, or metabolic state. Furthermore, while cultured neurons display Parkin-dependent axonal mitophagy, we find this is vanishingly rare in vivo under normal physiological conditions. Thus, both the spatial distribution and mechanism of mitochondrial quality control in vivo differ substantially from those observed in vitro. PMID:27413149

Mitochondrial dysfunction due to oxidative mitochondrial DNA damage is reduced through cooperative actions of diverse proteins.

PubMed

O'Rourke, Thomas W; Doudican, Nicole A; Mackereth, Melinda D; Doetsch, Paul W; Shadel, Gerald S

2002-06-01

The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2 Delta strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues.

Dysfunction of mitochondrial dynamics in the brains of scrapie-infected mice

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

Choi, Hong-Seok; Ilsong Institute of Life Science, Hallym University, 1605-4 Gwanyang-dong, Dongan-gu, Anyang, Gyeonggi-do 431-060; Choi, Yeong-Gon

Highlights: • Mfn1 and Fis1 are significantly increased in the hippocampal region of the ME7 prion-infected brain, whereas Dlp1 is significantly decreased in the infected brain. • Dlp1 is significantly decreased in the cytosolic fraction of the hippocampus in the infected brain. • Neuronal mitochondria in the prion-infected brains are enlarged and swollen compared to those of control brains. • There are significantly fewer mitochondria in the ME7-infected brain compared to the number in control brain. - Abstract: Mitochondrial dysfunction is a common and prominent feature of many neurodegenerative diseases, including prion diseases; it is induced by oxidative stress inmore » scrapie-infected animal models. In previous studies, we found swelling and dysfunction of mitochondria in the brains of scrapie-infected mice compared to brains of controls, but the mechanisms underlying mitochondrial dysfunction remain unclear. To examine whether the dysregulation of mitochondrial proteins is related to the mitochondrial dysfunction associated with prion disease, we investigated the expression patterns of mitochondrial fusion and fission proteins in the brains of ME7 prion-infected mice. Immunoblot analysis revealed that Mfn1 was up-regulated in both whole brain and specific brain regions, including the cerebral cortex and hippocampus, of ME7-infected mice compared to controls. Additionally, expression levels of Fis1 and Mfn2 were elevated in the hippocampus and the striatum, respectively, of the ME7-infected brain. In contrast, Dlp1 expression was significantly reduced in the hippocampus in the ME7-infected brain, particularly in the cytosolic fraction. Finally, we observed abnormal mitochondrial enlargement and histopathological change in the hippocampus of the ME7-infected brain. These observations suggest that the mitochondrial dysfunction, which is presumably caused by the dysregulation of mitochondrial fusion and fission proteins, may contribute to the neuropathological changes associated with prion disease.« less

Ammonia-induced mitochondrial dysfunction and energy metabolism disturbances in isolated brain and liver mitochondria, and the effect of taurine administration: relevance to hepatic encephalopathy treatment

PubMed Central

Niknahad, Hossein; Jamshidzadeh, Akram; Zarei, Mahdi; Ommati, Mohammad Mehdi

2017-01-01

Introduction Ammonia-induced oxidative stress, mitochondrial dysfunction, and energy crisis are known as some the major mechanisms of brain injury in hepatic encephalopathy (HE). Hyperammonemia also affects the liver and hepatocytes. Therefore, targeting mitochondria seems to be a therapeutic point of intervention in the treatment of HE. Taurine is an abundant amino acid in the human body. Several biological functions including the mitochondrial protective properties are attributed to this amino acid. The aim of this study is to evaluate the effect of taurine administration on ammonia-induced mitochondrial dysfunction. Material and methods Isolated mice liver and brain mitochondria were exposed to different concentrations of ammonia (1, 5, 10, and 20 mM) and taurine (1, 5, and 10 mM), and several mitochondrial indices were assessed. Results It was found that ammonia inhibited mitochondrial dehydrogenases activity caused collapse of mitochondrial membrane potential (MMP), induced mitochondrial swelling (MPP), and increased reactive oxygen species (ROS) in isolated liver and brain mitochondria. Furthermore, a significant amount of lipid peroxidation (LPO), along with glutathione (GSH) and ATP depletion, was detected in ammonia exposed mitochondria. Taurine administration (5 and 10 mM) mitigated ammonia-induced mitochondrial dysfunction. Conclusions The current investigation demonstrates that taurine is instrumental in preserving brain and liver mitochondrial function in a hyperammonemic environment. The data suggest taurine as a potential protective agent with a therapeutic capability against hepatic encephalopathy and hyperammonemia. PMID:29062904

Mitochondrial dysfunction and organophosphorus compounds

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

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

2013-07-01

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

Protective effect of hydroxytyrosol in arsenic-induced mitochondrial dysfunction in rat brain.

PubMed

Soni, Manisha; Prakash, Chandra; Sehwag, Sfurti; Kumar, Vijay

2017-07-01

The present study was planned to investigate the protective effect of hydroxytyrosol (HT) against arsenic (As)-induced mitochondrial dysfunction in rat brain. Rats exposed to sodium arsenite (25 ppm for 8 weeks) showed decreased mitochondrial complexes (I, II, IV) activities, mitochondrial superoxide dismutase (MnSOD), and catalase activities in brain mitochondria. As-treated rats showed reduced mRNA expression of complex I (ND-1, ND-2), IV (COX-1, COX-4) subunits, and uncoupling protein-2 (UCP-2). In addition to this, As exposure downregulated the protein expression of MnSOD. Administration of HT with As restored the enzymatic activities of mitochondrial complexes, MnSOD and catalase, increased the mRNA levels of complexes subunits and UCP-2 as well as proteins level of MnSOD. These results suggest that HT efficiently restores mitochondrial dysfunction in As neurotoxicity and might be used as potential mitoprotective agent in future. © 2017 Wiley Periodicals, Inc.

The Paradox of Mitochondrial Dysfunction and Extended Longevity

PubMed Central

Munkácsy, Erin; Rea, Shane L.

2014-01-01

Mitochondria play numerous, essential roles in the life of eukaryotes. Disruption of mitochondrial function in humans is often pathological or even lethal. Surprisingly, in some organisms mitochondrial dysfunction can result in life extension. This paradox has been studied most extensively in the long-lived Mit mutants of the nematode Caenorhabditis elegans. In this review, we explore the major responses that are activated following mitochondrial dysfunction in these animals and how these responses potentially act to extend their life. We focus our attention on five broad areas of current research – reactive oxygen species signaling, the mitochondrial unfolded protein response, autophagy, metabolic adaptation, and the roles played by various transcription factors. Lastly, we also examine why disruption of complexes I and II differ in their ability to induce the Mit phenotype and extend lifespan. PMID:24699406

EFFECTS OF THE ORGANOCHLORINE PESTICIDE METHOXYCHLOR ON DOPAMINE METABOLITES AND TRANSPORTERS IN THE MOUSE BRAIN

PubMed Central

Schuh, Rosemary A.; Richardson, Jason R.; Gupta, Rupesh K.; Flaws, Jodi A.; Fiskum, Gary

2009-01-01

Pesticide exposure has been suggested as an increased risk factor in developing Parkinson’s disease (PD). While the molecular mechanism underlying this association is not clear, several studies have demonstrated a role for mitochondrial dysfunction and oxidative damage in PD. Although data on specific pesticides associated with PD are often lacking, several lines of evidence point to the potential involvement of the organochlorine class of pesticides. Previously, we have found that the organochlorine pesticide methoxychlor (mxc) causes mitochondrial dysfunction and oxidative stress in isolated mitochondria. Here, we sought to determine whether mxc-induced mitochondrial dysfunction results in oxidative damage and dysfunction of the dopamine system. Adult female CD1 mice were dosed with either vehicle (sesame oil) or mxc (16, 32, or 64 mg/kg/day) for 20 consecutive days. Following treatment, we observed a dose-related increase in protein carbonyl levels in non-synaptic mitochondria, indicating oxidative modification of mitochondrial proteins which may lead to mitochondrial dysfunction. Mxc exposure also caused a dose-related decrease in striatal levels of dopamine (16–31%), which were accompanied by decreased levels of the dopamine transporter (DAT; 35–48%) and the vesicular monoamine transporter 2 (VMAT2; 21–44%). Because mitochondrial dysfunction, oxidative damage, and decreased levels of DAT and VMAT2 are found in PD patients, our data suggests that mxc should be investigated as a possible candidate involved in the association of pesticides with increased risk for PD, particularly in highly-exposed populations. PMID:19459224

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

The Mitochondria-Targeted Antioxidant Mitoquinone Protects against Cold Storage Injury of Renal Tubular Cells and Rat Kidneys

PubMed Central

Mitchell, Tanecia; Rotaru, Dumitru; Saba, Hamida; Smith, Robin A. J.; Murphy, Michael P.

2011-01-01

The majority of kidneys used for transplantation are obtained from deceased donors. These kidneys must undergo cold preservation/storage before transplantation to preserve tissue quality and allow time for recipient selection and transport. However, cold storage (CS) can result in tissue injury, kidney discardment, or long-term renal dysfunction after transplantation. We have previously determined mitochondrial superoxide and other downstream oxidants to be important signaling molecules that contribute to CS plus rewarming (RW) injury of rat renal proximal tubular cells. Thus, this study's purpose was to determine whether adding mitoquinone (MitoQ), a mitochondria-targeted antioxidant, to University of Wisconsin (UW) preservation solution could offer protection against CS injury. CS was initiated by placing renal cells or isolated rat kidneys in UW solution alone (4 h at 4°C) or UW solution containing MitoQ or its control compound, decyltriphenylphosphonium bromide (DecylTPP) (1 μM in vitro; 100 μM ex vivo). Oxidant production, mitochondrial function, cell viability, and alterations in renal morphology were assessed after CS exposure. CS induced a 2- to 3-fold increase in mitochondrial superoxide generation and tyrosine nitration, partial inactivation of mitochondrial complexes, and a significant increase in cell death and/or renal damage. MitoQ treatment decreased oxidant production ∼2-fold, completely prevented mitochondrial dysfunction, and significantly improved cell viability and/or renal morphology, whereas DecylTPP treatment did not offer any protection. These findings implicate that MitoQ could potentially be of therapeutic use for reducing organ preservation damage and kidney discardment and/or possibly improving renal function after transplantation. PMID:21159749

The mitochondria-targeted antioxidant mitoquinone protects against cold storage injury of renal tubular cells and rat kidneys.

PubMed

Mitchell, Tanecia; Rotaru, Dumitru; Saba, Hamida; Smith, Robin A J; Murphy, Michael P; MacMillan-Crow, Lee Ann

2011-03-01

The majority of kidneys used for transplantation are obtained from deceased donors. These kidneys must undergo cold preservation/storage before transplantation to preserve tissue quality and allow time for recipient selection and transport. However, cold storage (CS) can result in tissue injury, kidney discardment, or long-term renal dysfunction after transplantation. We have previously determined mitochondrial superoxide and other downstream oxidants to be important signaling molecules that contribute to CS plus rewarming (RW) injury of rat renal proximal tubular cells. Thus, this study's purpose was to determine whether adding mitoquinone (MitoQ), a mitochondria-targeted antioxidant, to University of Wisconsin (UW) preservation solution could offer protection against CS injury. CS was initiated by placing renal cells or isolated rat kidneys in UW solution alone (4 h at 4°C) or UW solution containing MitoQ or its control compound, decyltriphenylphosphonium bromide (DecylTPP) (1 μM in vitro; 100 μM ex vivo). Oxidant production, mitochondrial function, cell viability, and alterations in renal morphology were assessed after CS exposure. CS induced a 2- to 3-fold increase in mitochondrial superoxide generation and tyrosine nitration, partial inactivation of mitochondrial complexes, and a significant increase in cell death and/or renal damage. MitoQ treatment decreased oxidant production ~2-fold, completely prevented mitochondrial dysfunction, and significantly improved cell viability and/or renal morphology, whereas DecylTPP treatment did not offer any protection. These findings implicate that MitoQ could potentially be of therapeutic use for reducing organ preservation damage and kidney discardment and/or possibly improving renal function after transplantation.

Creatine protects against mitochondrial dysfunction associated with HIV-1 Tat-induced neuronal injury.

PubMed

Stevens, Patrick R; Gawryluk, Jeremy W; Hui, Liang; Chen, Xuesong; Geiger, Jonathan D

2014-01-01

HIV-1 infected individuals live longer but experience a prevalence rate of over 50% for HIV-1 associated neurocognitive disorders (HAND) for which no effective treatment is available. Viral and cellular factors secreted by HIV-1 infected cells lead to neuronal injury and HIV-1 Tat continues to be implicated in the pathogenesis of HAND. Here we tested the hypothesis that creatine protected against HIV-1 Tat-induced neuronal injury by preventing mitochondrial bioenergetic crisis and/or redox catastrophe. Creatine blocked HIV-1 Tat(1-72)-induced increases in neuron cell death and synaptic area loss. Creatine protected against HIV-1 Tat-induced decreases in ATP. Creatine and creatine plus HIV-1 Tat increased cellular levels of creatine, and creatine plus HIV-1 Tat further decreased ratios of phosphocreatine to creatine observed with creatine or HIV-1 Tat treatments alone. Additionally, creatine protected against HIV-1 Tat-induced mitochondrial hypopolarization and HIV-1 Tat-induced mitochondrial permeability transition pore opening. Thus, creatine may be a useful adjunctive therapy against HAND.

Transcriptomic and proteomic landscape of mitochondrial dysfunction reveals secondary coenzyme Q deficiency in mammals

PubMed Central

Atanassov, Ilian; Kuznetsova, Irina; Hinze, Yvonne; Mourier, Arnaud; Filipovska, Aleksandra

2017-01-01

Dysfunction of the oxidative phosphorylation (OXPHOS) system is a major cause of human disease and the cellular consequences are highly complex. Here, we present comparative analyses of mitochondrial proteomes, cellular transcriptomes and targeted metabolomics of five knockout mouse strains deficient in essential factors required for mitochondrial DNA gene expression, leading to OXPHOS dysfunction. Moreover, we describe sequential protein changes during post-natal development and progressive OXPHOS dysfunction in time course analyses in control mice and a middle lifespan knockout, respectively. Very unexpectedly, we identify a new response pathway to OXPHOS dysfunction in which the intra-mitochondrial synthesis of coenzyme Q (ubiquinone, Q) and Q levels are profoundly decreased, pointing towards novel possibilities for therapy. Our extensive omics analyses provide a high-quality resource of altered gene expression patterns under severe OXPHOS deficiency comparing several mouse models, that will deepen our understanding, open avenues for research and provide an important reference for diagnosis and treatment. PMID:29132502

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.

Brain mitochondrial iron accumulates in Huntington's disease, mediates mitochondrial dysfunction, and can be removed pharmacologically.

PubMed

Agrawal, Sonal; Fox, Julia; Thyagarajan, Baskaran; Fox, Jonathan H

2018-05-20

Mitochondrial bioenergetic dysfunction is involved in neurodegeneration in Huntington's disease (HD). Iron is critical for normal mitochondrial bioenergetics but can also contribute to pathogenic oxidation. The accumulation of iron in the brain occurs in mouse models and in human HD. Yet the role of mitochondria-related iron dysregulation as a contributor to bioenergetic pathophysiology in HD is unclear. We demonstrate here that human HD and mouse model HD (12-week R6/2 and 12-month YAC128) brains accumulated mitochondrial iron and showed increased expression of iron uptake protein mitoferrin 2 and decreased iron-sulfur cluster synthesis protein frataxin. Mitochondria-enriched fractions from mouse HD brains had deficits in membrane potential and oxygen uptake and increased lipid peroxidation. In addition, the membrane-permeable iron-selective chelator deferiprone (1 μM) rescued these effects ex-vivo, whereas hydrophilic iron and copper chelators did not. A 10-day oral deferiprone treatment in 9-week R6/2 HD mice indicated that deferiprone removed mitochondrial iron, restored mitochondrial potentials, decreased lipid peroxidation, and improved motor endurance. Neonatal iron supplementation potentiates neurodegeneration in mouse models of HD by unknown mechanisms. We found that neonatal iron supplementation increased brain mitochondrial iron accumulation and potentiated markers of mitochondrial dysfunction in HD mice. Therefore, bi-directional manipulation of mitochondrial iron can potentiate and protect against markers of mouse HD. Our findings thus demonstrate the significance of iron as a mediator of mitochondrial dysfunction and injury in mouse models of human HD and suggest that targeting the iron-mitochondrial pathway may be protective. Copyright © 2018 Elsevier Inc. All rights reserved.

Reversal of mitochondrial dysfunction by coenzyme Q10 supplement improves endothelial function in patients with ischaemic left ventricular systolic dysfunction: a randomized controlled trial.

PubMed

Dai, Yuk-Ling; Luk, Ting-Hin; Yiu, Kai-Hang; Wang, Mei; Yip, Pandora M C; Lee, Stephen W L; Li, Sheung-Wai; Tam, Sidney; Fong, Bonnie; Lau, Chu-Pak; Siu, Chung-Wah; Tse, Hung-Fat

2011-06-01

Coronary artery disease (CAD) is associated with endothelial dysfunction and mitochondrial dysfunction (MD). The aim of this study was to investigate whether co-enzyme Q10 (CoQ) supplementation, which is an obligatory coenzyme in the mitochondrial respiratory transport chain, can reverse MD and improve endothelial function in patients with ischaemic left ventricular systolic dysfunction (LVSD). We performed a randomized, double-blind, placebo-controlled trial to determine the effects of CoQ supplement (300 mg/day, n=28) vs. placebo (controls, n=28) for 8 weeks on brachial flow-mediated dilation (FMD) in patients with ischaemic LVSD(left ventricular ejection fraction <45%). Mitochondrial function was determined by plasma lactate/pyruvate ratio (LP ratio). After 8 weeks, CoQ-treated patients had significant increases in plasma CoQ concentration (treatment effect 2.20 μg/mL, P<0.001) and FMD (treatment effect 1.51%, P=0.03); and decrease in LP ratio (treatment effect -2.46, P=0.03) compared with controls. However, CoQ treatment did not alter nitroglycerin-mediated dilation, blood pressure, blood levels of fasting glucose, haemoglobin A1c, lipid profile, high-sensitivity C-reactive protein and oxidative stress as determined by serum superoxide dismutase and 8-isoprostane (all P>0.05). Furthermore, the reduction in LP ratio significantly correlated with improvement in FMD (r=-0.29, P=0.047). In patients with ischaemic LVSD, 8 weeks supplement of CoQ improved mitochondrial function and FMD; and the improvement of FMD correlated with the change in mitochondrial function, suggesting that CoQ improved endothelial function via reversal of mitochondrial dysfunction in patients with ischaemic LVSD. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

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

PubMed

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

2018-02-01

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

Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Wilson, Christina L.; Natarajan, Vaishaali; Hayward, Stephen L.; Khalimonchuk, Oleh; Kidambi, Srivatsan

2015-11-01

Titanium dioxide (TiO2) nanoparticles are currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTracker® Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 +/- 10.56 ppm, 136.0 +/- 31.73 ppm and 62.37 +/- 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of a loss in vital astrocyte function. TiO2 nanoparticles also induced an increase in reactive oxygen species generation, and a decrease in mitochondrial membrane potential, suggesting mitochondrial damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticle exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticle exposure has potential implications in astrocyte-mediated neurological dysfunction.Titanium dioxide (TiO2) nanoparticles are currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTracker® Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 +/- 10.56 ppm, 136.0 +/- 31.73 ppm and 62.37 +/- 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of a loss in vital astrocyte function. TiO2 nanoparticles also induced an increase in reactive oxygen species generation, and a decrease in mitochondrial membrane potential, suggesting mitochondrial damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticle exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticle exposure has potential implications in astrocyte-mediated neurological dysfunction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03646a

Activation of the NLRP3 inflammasome induces vascular dysfunction in obese OLETF rats

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

Liu, Penghao; Xie, Qihai; Wei, Tong

Objective: Obesity-induced vascular dysfunction is related to chronic low-grade systemic inflammation. Recent studies indicate that NLRP3, a multiprotein complex formed by NOD-like receptor (NLR) family members, is a key component mediating internal sterile inflammation, but the role in obesity-related vascular dysfunction is largely unknown. In the present study, we investigate whether NLRP3 activation is involved in vascular inflammation in obese Otsuka Long-Evans Tokushima Fatty rats (OLETF). Methods and results: Male OLETF with their control Long-Evans Tokushima Otsuka rats (LETO) were studied at 3 and 12 months of age. Aortic relaxation in response to acetylcholine decreased gradually with age in bothmore » strains, with early and persistent endothelium dysfunction in obese OLETF compared with age-matched LETO controls. These changes are associated with parallel changes of aortic endothelial nitric oxide synthase (eNOS) content, macrophage accumulation and intimal thickening. NLRP3 increased in OLETF rats compared to LETO. Consistent with inflammasome activation, the conversion of procaspase-1 to cleaved and activated forms as well as IL-1β markedly increased in OLETF rats. Additionally, we observed increased expression of dynamin-related protein-1 (Drp1) and decreased fusion-relative protein optic atropy-1(OPA1). Altered mitochondrial dynamics was associated with elevated oxidative stress level in OLETF aortas. Conclusions: These results demonstrate that obesity seems to accelerate endothelial dysfunction in OLETFs via the activation of NLRP3 and mitochondrial dysfunction. - Highlights: • NLRP3 is involved in obesity-induced vascular dysfunction. • Impaired mitochondrial dynamics may have been linked to mitochondrial defect and inflammasome activation. • Obesity seems to accelerate vascular dysfunction via NLRP3 activation and mitochondrial dysfunction.« less

The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders

PubMed Central

Liao, Yajin; Dong, Yuan; Cheng, Jinbo

2017-01-01

The mitochondrial calcium uniporter (MCU)—a calcium uniporter on the inner membrane of mitochondria—controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP); however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders. PMID:28208618

TDP1 repairs nuclear and mitochondrial DNA damage induced by chain-terminating anticancer and antiviral nucleoside analogs

PubMed Central

Huang, Shar-yin N.; Murai, Junko; Dalla Rosa, Ilaria; Dexheimer, Thomas S.; Naumova, Alena; Gmeiner, William H.; Pommier, Yves

2013-01-01

Chain-terminating nucleoside analogs (CTNAs) that cause stalling or premature termination of DNA replication forks are widely used as anticancer and antiviral drugs. However, it is not well understood how cells repair the DNA damage induced by these drugs. Here, we reveal the importance of tyrosyl–DNA phosphodiesterase 1 (TDP1) in the repair of nuclear and mitochondrial DNA damage induced by CTNAs. On investigating the effects of four CTNAs—acyclovir (ACV), cytarabine (Ara-C), zidovudine (AZT) and zalcitabine (ddC)—we show that TDP1 is capable of removing the covalently linked corresponding CTNAs from DNA 3′-ends. We also show that Tdp1−/− cells are hypersensitive and accumulate more DNA damage when treated with ACV and Ara-C, implicating TDP1 in repairing CTNA-induced DNA damage. As AZT and ddC are known to cause mitochondrial dysfunction, we examined whether TDP1 repairs the mitochondrial DNA damage they induced. We find that AZT and ddC treatment leads to greater depletion of mitochondrial DNA in Tdp1−/− cells. Thus, TDP1 seems to be critical for repairing nuclear and mitochondrial DNA damage caused by CTNAs. PMID:23775789

The Emerging Role of Disturbed CoQ Metabolism in Nonalcoholic Fatty Liver Disease Development and Progression

PubMed Central

Botham, Kathleen M.; Napolitano, Mariarosaria; Bravo, Elena

2015-01-01

Although non-alcoholic fatty liver disease (NAFLD), characterised by the accumulation of triacylglycerol in the liver, is the most common liver disorder, the causes of its development and progression to the more serious non-alcoholic steatohepatitis (NASH) remain incompletely understood. Oxidative stress has been implicated as a key factor in both these processes, and mitochondrial dysfunction and inflammation are also believed to play a part. Coenzyme Q (CoQ) is a powerful antioxidant found in all cell membranes which has an essential role in mitochondrial respiration and also has anti-inflammatory properties. NAFLD has been shown to be associated with disturbances in plasma and liver CoQ concentrations, but the relationship between these changes and disease development and progression is not yet clear. Dietary supplementation with CoQ has been found to be hepatoprotective and to reduce oxidative stress and inflammation as well as improving mitochondrial dysfunction, suggesting that it may be beneficial in NAFLD. However, studies using animal models or patients with NAFLD have given inconclusive results. Overall, evidence is now emerging to indicate that disturbances in CoQ metabolism are involved in NAFLD development and progression to NASH, and this highlights the need for further studies with human subjects to fully clarify its role. PMID:26633474

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

PubMed Central

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

2017-01-01

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

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

PubMed

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

2017-08-26

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

Reduction in Autophagy by (-)-Epigallocatechin-3-Gallate (EGCG): a Potential Mechanism of Prevention of Mitochondrial Dysfunction After Subarachnoid Hemorrhage.

PubMed

Chen, Ying; Huang, Liyong; Zhang, Huiyong; Diao, Xiling; Zhao, Shuyang; Zhou, Wenke

2017-01-01

Mitochondrial dysfunction and subsequent autophagy, which are common features in central nervous system (CNS) disorders, were found to contribute to neuronal cell injury after subarachnoid hemorrhage (SAH). (-)-Epigallocatechin-3-gallate (EGCG), the main biological active of tea catechin, is well known for its beneficial effects in the treatment of CNS diseases. Here, the ability of EGCG to rescue cellular injury and mitochondrial function following the improvement of autophagic flux after SAH was investigated. As expected, EGCG-protected mitochondrial function depended on the inhibition of cytosolic Ca 2+ concentration ([Ca 2+ ] i ) influx via voltage-gated calcium channels (VGCCs) and, consequently, mitochondrial Ca 2+ concentration ([Ca 2+ ] m ) overload via mitochondrial Ca 2+ uniporter (MCU). The attenuated [Ca 2+ ] i and [Ca 2+ ] m levels observed in the EGCG-treated group likely lessened oxyhemoglobin (OxyHb)-induced mitochondrial dysfunction, including mitochondrial membrane potential depolarization, mitochondrial membrane permeability transition pore (mPTP) opening, reactive oxygen species (ROS), and cytochrosome c (cyt c) releasing. Subsequently, EGCG can restore the disrupted autophagy flux after SAH both at the initiation and formation stages by regulating Atg5, LC3B, and Becn-1 (Beclin-1) mRNA expressions. Thus, precondition EGCG resulted in autophagosomes and more autolysosomes compared with SAH group. As a result, EGCG pre-treatment increased the neurological score and decreased cell death. This study suggested that the mitochondrial dysfunction and abnormal autophagy flux synergistically contribute to SAH pathogenesis. Thus, EGCG can be regarded as a new pharmacological agent that targets both mitochondria and altered autophagy in SAH therapy.

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

PubMed

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

2018-04-18

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

Mitochondrial Dysfunction and Oxidative Stress Promote Apoptotic Cell Death in the Striatum via Cytochrome c/Caspase-3 Signaling Cascade Following Chronic Rotenone Intoxication in Rats

PubMed Central

Lin, Tsu-Kung; Cheng, Ching-Hsiao; Chen, Shang-Der; Liou, Chia-Wei; Huang, Chi-Ren; Chuang, Yao-Chung

2012-01-01

Parkinson’s disease (PD) is a progressive neurological disorder marked by nigrostriatal dopaminergic degeneration. Evidence suggests that mitochondrial dysfunction may be linked to PD through a variety of different pathways, including free-radical generation and dysfunction of the mitochondrial Complex I activity. In Lewis rats, chronic systemic administration of a specific mitochondrial Complex I inhibitor, rotenone (3 mg/kg/day) produced parkinsonism-like symptoms. Increased oxidized proteins and peroxynitrite, and mitochondrial or cytosol translocation of Bim, Bax or cytochrome c in the striatum was observed after 2–4 weeks of rotenone infusion. After 28 days of systemic rotenone exposure, imunohistochemical staining for tyrosine hydroxylase indicated nigrostriatal dopaminergic neuronal cell degeneration. Characteristic histochemical (TUNEL or activated caspase-3 staining) or ultrastructural (electron microscopy) features of apoptotic cell death were present in the striatal neuronal cell after chronic rotenone intoxication. We conclude that chronic rotenone intoxication may enhance oxidative and nitrosative stress that induces mitochondrial dysfunction and ultrastructural damage, resulting in translocation of Bim and Bax from cytosol to mitochondria that contributes to apoptotic cell death in the striatum via cytochrome c/caspase-3 signaling cascade. PMID:22942730

Mitochondrial dysfunction in obesity.

PubMed

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

2018-01-01

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

Mitochondrial Disorders of DNA Polymerase γ Dysfunction

PubMed Central

Zhang, Linsheng; Chan, Sherine S. L.; Wolff, Daynna J.

2011-01-01

Context Primary mitochondrial dysfunction is one of the most common causes of inherited disorders predominantly involving the neuromuscular system. Advances in the molecular study of mitochondrial DNA have changed our vision and our approach to primary mitochondrial disorders. Many of the mitochondrial disorders are caused by mutations in nuclear genes and are inherited in an autosomal recessive pattern. Among the autosomal inherited mitochondrial disorders, those related to DNA polymerase γ dysfunction are the most common and the best studied. Understanding the molecular mechanisms and being familiar with the recent advances in laboratory diagnosis of this group of mitochondrial disorders are essential for pathologists to interpret abnormal histopathology and laboratory results and to suggest further studies for a definitive diagnosis. Objectives To help pathologists better understand the common clinical syndromes originating from mutations in DNA polymerase γ and its associated proteins and use the stepwise approach of clinical, laboratory, and pathologic diagnosis of these syndromes. Data Sources Review of pertinent published literature and relevant Internet databases. Conclusions Mitochondrial disorders are now better recognized with the development of molecular tests for clinical diagnosis. A cooperative effort among primary physicians, diagnostic pathologists, geneticists, and molecular biologists with expertise in mitochondrial disorders is required to reach a definitive diagnosis. PMID:21732785

Impaired Cardiolipin Biosynthesis Prevents Hepatic Steatosis and Diet-Induced Obesity

PubMed Central

Cole, Laura K.; Mejia, Edgard M.; Vandel, Marilyne; Sparagna, Genevieve C.; Claypool, Steven M.; Dyck-Chan, Laura; Klein, Julianne

2016-01-01

Mitochondria are the nexus of energy metabolism, and consequently their dysfunction has been implicated in the development of metabolic complications and progression to insulin resistance and type 2 diabetes. The unique tetra-acyl phospholipid cardiolipin (CL) is located in the inner mitochondrial membrane, where it maintains mitochondrial integrity. Here we show that knockdown of Tafazzin (TAZ kd), a CL transacylase, in mice results in protection against the development of obesity, insulin resistance, and hepatic steatosis. We determined that hypermetabolism protected TAZ kd mice from weight gain. Unexpectedly, the large reduction of CL in the heart and skeletal muscle of TAZ kd mice was not mirrored in the liver. As a result, TAZ kd mice exhibited normal hepatic mitochondrial supercomplex formation and elevated hepatic fatty acid oxidation. Collectively, these studies identify a key role for hepatic CL remodeling in regulating susceptibility to insulin resistance and as a novel therapeutic target for diet-induced obesity. PMID:27495222

Mitochondria as a target in the therapeutic properties of curcumin.

PubMed

Trujillo, Joyce; Granados-Castro, Luis Fernando; Zazueta, Cecilia; Andérica-Romero, Ana Cristina; Chirino, Yolanda Irasema; Pedraza-Chaverrí, José

2014-12-01

Curcumin, a phenolic compound extracted from Curcuma longa, is commonly used in Asia as a spice and pigment and has several biological functions, particularly antioxidant properties. It has been reported that curcumin exhibits bifunctional antioxidant properties related to its capability to react directly with reactive oxygen species (ROS) and also to its ability to induce the expression of cytoprotective and antioxidant proteins through the transcription factor nuclear factor-erythroid-2-related factor 2 (Nrf2). Recently, it has been postulated that the mitochondrial function and metabolism are associated with Nrf2 and that curcumin has shown activities against mitochondrial dysfunction. The damage in mitochondria has been implicated in the pathogenesis of diseases like diabetes, cancer, aging, and neurodegenerative disorders. This review focuses on some of the most recent findings of curcumin properties that suggest a close relationship of this antioxidant with the mitochondrial function. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein kinase C-ε activation induces mitochondrial dysfunction and fragmentation in renal proximal tubules

PubMed Central

Bakajsova, Diana; Samarel, Allen M.

2011-01-01

PKC-ε activation mediates protection from ischemia-reperfusion injury in the myocardium. Mitochondria are a subcellular target of these protective mechanisms of PKC-ε. Previously, we have shown that PKC-ε activation is involved in mitochondrial dysfunction in oxidant-injured renal proximal tubular cells (RPTC; Nowak G, Bakajsova D, Clifton GL Am J Physiol Renal Physiol 286: F307–F316, 2004). The goal of this study was to examine the role of PKC-ε activation in mitochondrial dysfunction and to identify mitochondrial targets of PKC-ε in RPTC. The constitutively active and inactive mutants of PKC-ε were overexpressed in primary cultures of RPTC using the adenoviral technique. Increases in active PKC-ε levels were accompanied by PKC-ε translocation to mitochondria. Sustained PKC-ε activation resulted in decreases in state 3 respiration, electron transport rate, ATP production, ATP content, and activities of complexes I and IV and F0F1-ATPase. Furthermore, PKC-ε activation increased mitochondrial membrane potential and oxidant production and induced mitochondrial fragmentation and RPTC death. Accumulation of the dynamin-related protein in mitochondria preceded mitochondrial fragmentation. Antioxidants blocked PKC-ε-induced increases in the oxidant production but did not prevent mitochondrial fragmentation and cell death. The inactive PKC-ε mutant had no effect on mitochondrial functions, morphology, oxidant production, and RPTC viability. We conclude that active PKC-ε targets complexes I and IV and F0F1-ATPase in RPTC. PKC-ε activation mediates mitochondrial dysfunction, hyperpolarization, and fragmentation. It also induces oxidant generation and cell death, but oxidative stress is not the mechanism of RPTC death. These results show that in contrast to protective effects of PKC-ε activation in cardiomyocytes, sustained PKC-ε activation is detrimental to mitochondrial function and viability in RPTC. PMID:21289057

Tempol, a Superoxide Dismutase Mimetic Agent, Ameliorates Cisplatin-Induced Nephrotoxicity through Alleviation of Mitochondrial Dysfunction in Mice

PubMed Central

Ahmed, Lamiaa A.; Shehata, Nagwa I.; Abdelkader, Noha F.; Khattab, Mahmoud M.

2014-01-01

Background Mitochondrial dysfunction is a crucial mechanism by which cisplatin, a potent chemotherapeutic agent, causes nephrotoxicity where mitochondrial electron transport complexes are shifted mostly toward imbalanced reactive oxygen species versus energy production. In the present study, the protective role of tempol, a membrane-permeable superoxide dismutase mimetic agent, was evaluated on mitochondrial dysfunction and the subsequent damage induced by cisplatin nephrotoxicity in mice. Methods and Findings Nephrotoxicity was assessed 72 h after a single i.p. injection of cisplatin (25 mg/kg) with or without oral administration of tempol (100 mg/kg/day). Serum creatinine and urea as well as glucosuria and proteinuria were evaluated. Both kidneys were isolated for estimation of oxidative stress markers, adenosine triphosphate (ATP) content and caspase-3 activity. Moreover, mitochondrial oxidative phosphorylation capacity, complexes I–IV activities and mitochondrial nitric oxide synthase (mNOS) protein expression were measured along with histological examinations of renal tubular damage and mitochondrial ultrastructural changes. Tempol was effective against cisplatin-induced elevation of serum creatinine and urea as well as glucosuria and proteinuria. Moreover, pretreatment with tempol notably inhibited cisplatin-induced oxidative stress and disruption of mitochondrial function by restoring mitochondrial oxidative phosphorylation, complexes I and III activities, mNOS protein expression and ATP content. Tempol also provided significant protection against apoptosis, tubular damage and mitochondrial ultrastructural changes. Interestingly, tempol did not interfere with the cytotoxic effect of cisplatin against the growth of solid Ehrlich carcinoma. Conclusion This study highlights the potential role of tempol in inhibiting cisplatin-induced nephrotoxicity without affecting its antitumor activity via amelioration of oxidative stress and mitochondrial dysfunction. PMID:25271439

The role of weight loss and exercise in correcting skeletal muscle mitochondrial abnormalities in obesity, diabetes and aging.

PubMed

Toledo, Frederico G S; Goodpaster, Bret H

2013-10-15

Mitochondria within skeletal muscle have been implicated in insulin resistance of obesity and type 2 diabetes mellitus as well as impaired muscle function with normal aging. Evaluating the potential of interventions to improve mitochondria is clearly relevant to the prevention or treatment of metabolic diseases and age-related dysfunction. This review provides an overview and critical evaluation of the effects of weight loss and exercise interventions on skeletal muscle mitochondria, along with implications for insulin resistance, obesity, type 2 diabetes and aging. The available literature strongly suggests that the lower mitochondrial capacity associated with obesity, type 2 diabetes and aging is not an irreversible lesion. However, weight loss does not appear to affect this response, even when the weight loss is extreme. In contrast, increasing physical activity improves mitochondrial content and perhaps the function of individual mitochondrion. Despite the consistent effect of exercise to improve mitochondrial capacity, studies mechanistically linking mitochondria to insulin resistance, reductions in intramyocellular lipid or improvement in muscle function remain inconclusive. In summary, studies of diet and exercise training have advanced our understanding of the link between mitochondrial oxidative capacity and insulin resistance in obesity, type 2 diabetes and aging. Nevertheless, additional inquiry is necessary to establish the significance and clinical relevance of those perturbations, which could lead to targeted therapies for a myriad of conditions and diseases involving mitochondria. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Mitochondrial DNA sequence data reveals association of haplogroup U with psychosis in bipolar disorder.

PubMed

Frye, Mark A; Ryu, Euijung; Nassan, Malik; Jenkins, Gregory D; Andreazza, Ana C; Evans, Jared M; McElroy, Susan L; Oglesbee, Devin; Highsmith, W Edward; Biernacka, Joanna M

2017-01-01

Converging genetic, postmortem gene-expression, cellular, and neuroimaging data implicate mitochondrial dysfunction in bipolar disorder. This study was conducted to investigate whether mitochondrial DNA (mtDNA) haplogroups and single nucleotide variants (SNVs) are associated with sub-phenotypes of bipolar disorder. MtDNA from 224 patients with Bipolar I disorder (BPI) was sequenced, and association of sequence variations with 3 sub-phenotypes (psychosis, rapid cycling, and adolescent illness onset) was evaluated. Gene-level tests were performed to evaluate overall burden of minor alleles for each phenotype. The haplogroup U was associated with a higher risk of psychosis. Secondary analyses of SNVs provided nominal evidence for association of psychosis with variants in the tRNA, ND4 and ND5 genes. The association of psychosis with ND4 (gene that encodes NADH dehydrogenase 4) was further supported by gene-level analysis. Preliminary analysis of mtDNA sequence data suggests a higher risk of psychosis with the U haplogroup and variation in the ND4 gene implicated in electron transport chain energy regulation. Further investigation of the functional consequences of this mtDNA variation is encouraged. Copyright © 2016. Published by Elsevier Ltd.

Potential Therapeutic Benefits of Strategies Directed to Mitochondria

PubMed Central

Lesnefsky, Edward J.; Stowe, David F.

2010-01-01

Abstract The mitochondrion is the most important organelle in determining continued cell survival and cell death. Mitochondrial dysfunction leads to many human maladies, including cardiovascular diseases, neurodegenerative disease, and cancer. These mitochondria-related pathologies range from early infancy to senescence. The central premise of this review is that if mitochondrial abnormalities contribute to the pathological state, alleviating the mitochondrial dysfunction would contribute to attenuating the severity or progression of the disease. Therefore, this review will examine the role of mitochondria in the etiology and progression of several diseases and explore potential therapeutic benefits of targeting mitochondria in mitigating the disease processes. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate and manipulate mitochondrial function and genomics for therapeutic benefit. These approaches to treat mitochondrial dysfunction rationally could lead to selective protection of cells in different tissues and various disease states. However, most of these approaches are in their infancy. Antioxid. Redox Signal. 13, 279–347. PMID:20001744

Mitochondrial Disease: Clinical Aspects, Molecular Mechanisms, Translational Science, and Clinical Frontiers

PubMed Central

Thornton, Ben; Cohen, Bruce; Copeland, William; Maria, Bernard L.

2015-01-01

Mitochondrial medicine provides a metabolic perspective on the pathology of conditions linked with inadequate oxidative phosphorylation. Dysfunction in the mitochondrial machinery can result in improper energy production, leading to cellular injury or even apoptosis. Clinical presentations are often subtle, so clinicians must have a high index of suspicion to make early diagnoses. Symptoms could include muscle weakness and pain, seizures, loss of motor control, decreased visual and auditory functions, metabolic acidosis, acute developmental regression, and immune system dysfunction. The 2013 Neurobiology of Disease in Children Symposium, held in conjunction with the 42nd Annual Meeting of the Child Neurology Society, aimed to (1) describe accepted clinical phenotypes of mitochondrial disease produced from various mitochondrial mutations, (2) discuss contemporary understanding of molecular mechanisms that contribute to disease pathology, (3) highlight the systemic effects produced by dysfunction within the mitochondrial machinery, and (4) introduce current strategies that are being translated from bench to bedside as potential therapeutics. PMID:24916430

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

[MITOCHONDRIAL DYSFUNCTION: MODERN ASPECTS OF THERAPY (REVIEW)].

PubMed

Arveladze, G; Geladze, N; Khachapuridze, N; Bakhtadze, S; Kapanadze, N

2015-01-01

Mitochondrial diseases are considered as one of the major problems of modern interdisciplinary neonatology and pediatrics. Mitochondrial pathology can be revealed as refractory myoclonic or multifocal seizures, craniofacial dysostosis, dysmetabolic manifestations and respiratory disorders. Central nervous system (CNS), muscles, heart, liver and kidneys is involved in this pathological process. An important criterion for diagnosis of mitochondrial dysfunction is increases in blood lactate and pyruvate levels; the absolute criterion - molecular genetic diagnostic studies of mitochondrial DNA. Polymorphism of clinical symptoms complicates the process of early diagnostics, the lack clear recommendations complicates therapy. Modern aspects of treatment of mitochondrial dysfunction in various neurological syndromes are based primarily in improving the efficiency of the processes of oxidative phosphorylation at the system level. Dietary carbohydrate restriction, and medication (Coenzyme Q10, Idebenonum, Cofactors, drugs which reduce lactic acidosis- Dimephosphon, Dichloroacetate, Antioxidants, Anticonvulsants and Antidiabetic agents, vitamins C, E, K, hemotransfusions) is prescribed. Such complex approach allows us to achieve a reduction in lactate-acidosis, and improve the condition of patients in 70% of cases.

Melatonin and human mitochondrial diseases

PubMed Central

Sharafati-Chaleshtori, Reza; Shirzad, Hedayatollah; Rafieian-Kopaei, Mahmoud; Soltani, Amin

2017-01-01

Mitochondrial dysfunction is one of the main causative factors in a wide variety of complications such as neurodegenerative disorders, ischemia/reperfusion, aging process, and septic shock. Decrease in respiratory complex activity, increase in free radical production, increase in mitochondrial synthase activity, increase in nitric oxide production, and impair in electron transport system and/or mitochondrial permeability are considered as the main factors responsible for mitochondrial dysfunction. Melatonin, the pineal gland hormone, is selectively taken up by mitochondria and acts as a powerful antioxidant, regulating the mitochondrial bioenergetic function. Melatonin increases the permeability of membranes and is the stimulator of antioxidant enzymes including superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase. It also acts as an inhibitor of lipoxygenase. Melatonin can cause resistance to oxidation damage by fixing the microsomal membranes. Melatonin has been shown to retard aging and inhibit neurodegenerative disorders, ischemia/reperfusion, septic shock, diabetes, cancer, and other complications related to oxidative stress. The purpose of the current study, other than introducing melatonin, was to present the recent findings on clinical effects in diseases related to mitochondrial dysfunction including diabetes, cancer, gastrointestinal diseases, and diseases related to brain function. PMID:28400824

Novel interactions of mitochondria and reactive oxygen/nitrogen species in alcohol mediated liver disease

PubMed Central

Mantena, Sudheer K; King, Adrienne L; Andringa, Kelly K; Landar, Aimee; Darley-Usmar, Victor; Bailey, Shannon M

2007-01-01

Mitochondrial dysfunction is known to be a contributing factor to a number of diseases including chronic alcohol induced liver injury. While there is a detailed understanding of the metabolic pathways and proteins of the liver mitochondrion, little is known regarding how changes in the mitochondrial proteome may contribute to the development of hepatic pathologies. Emerging evidence indicates that reactive oxygen and nitrogen species disrupt mitochondrial function through post-translational modifications to the mitochondrial proteome. Indeed, various new affinity labeling reagents are available to test the hypothesis that post-translational modification of proteins by reactive species contributes to mitochondrial dysfunction and alcoholic fatty liver disease. Specialized proteomic techniques are also now available, which allow for identification of defects in the assembly of multi-protein complexes in mitochondria and the resolution of the highly hydrophobic proteins of the inner membrane. In this review knowledge gained from the study of changes to the mitochondrial proteome in alcoholic hepatotoxicity will be described and placed into a mechanistic framework to increase understanding of the role of mitochondrial dysfunction in liver disease. PMID:17854139

Mitochondrial Dysfunction in Chemotherapy-Induced Peripheral Neuropathy (CIPN)

PubMed Central

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

2015-01-01

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

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.

Elucidation of the mechanism of atorvastatin-induced myopathy in a rat model.

PubMed

El-Ganainy, Samar O; El-Mallah, Ahmed; Abdallah, Dina; Khattab, Mahmoud M; Mohy El-Din, Mahmoud M; El-Khatib, Aiman S

2016-06-01

Myopathy is among the well documented and the most disturbing adverse effects of statins. The underlying mechanism is still unknown. Mitochondrial dysfunction related to coenzyme Q10 decline is one of the proposed theories. The present study aimed to investigate the mechanism of atorvastatin-induced myopathy in rats. In addition, the mechanism of the coenzyme Q10 protection was investigated with special focus of mitochondrial alterations. Sprague-Dawely rats were treated orally either with atorvastatin (100mg/kg) or atorvastatin and coenzyme Q10 (100mg/kg). Myopathy was assessed by measuring serum creatine kinase (CK) and myoglobin levels together with examination of necrosis in type IIB fiber muscles. Mitochondrial dysfunction was evaluated by measuring muscle lactate/pyruvate ratio, ATP level, pAkt as well as mitochondrial ultrastructure examination. Atorvastatin treatment resulted in a rise in both CK (2X) and myoglobin (6X) level with graded degrees of muscle necrosis. Biochemical determinations showed prominent increase in lactate/pyruvate ratio and a decline in both ATP (>80%) and pAkt (>50%) levels. Ultrastructure examination showed mitochondrial swelling with disrupted organelle membrane. Co-treatment with coenzyme Q10 induced reduction in muscle necrosis as well as in CK and myoglobin levels. In addition, coenzyme Q10 improved all mitochondrial dysfunction parameters including mitochondrial swelling and disruption. These results presented a model for atorvastatin-induced myopathy in rats and proved that mitochondrial dysfunction is the main contributor in statin-myopathy pathophysiology. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Liver mitochondrial dysfunction and electron transport chain defect induced by high dietary copper in broilers.

PubMed

Yang, Fan; Cao, Huabin; Su, Rongsheng; Guo, Jianying; Li, Chengmei; Pan, Jiaqiang; Tang, Zhaoxin

2017-09-01

Copper is an important trace mineral in the diet of poultry due to its biological activity. However, limited information is available concerning the effects of high copper on mitochondrial dysfunction. In this study, 72 broilers were used to investigate the effects of high dietary copper on liver mitochondrial dysfunction and electron transport chain defect. Birds were fed with different concentrations [11, 110, 220, and 330 mg of copper/kg dry matter (DM)] of copper from tribasic copper chloride (TBCC). The experiment lasted for 60 d. Liver tissues on d 60 were subjected to histopathological observation. Additionally, liver mitochondrial function was recorded on d 12, 36, and 60. Moreover, a site-specific defect in the electron transport chain in liver mitochondria was also identified by using various chemical inhibitors of mitochondrial respiration. The results showed different degrees of degeneration, mitochondrial swelling, and high-density electrons in hepatocytes. In addition, the respiratory control ratio (RCR) and oxidative phosphorylation rate (OPR) in liver mitochondria increased at first and then decreased in high-dose groups. Moreover, hydrogen peroxide (H2O2) generation velocity in treated groups was higher than that in control group, which were magnified by inhibiting electron transport at Complex IV. The results indicated that high dietary copper could decline liver mitochondrial function in broilers. The presence of a site-specific defect at Complex IV in liver mitochondria may be responsible for liver mitochondrial dysfunction caused by high dietary copper. © 2017 Poultry Science Association Inc.

Regulation of Mitochondrial Function and Glutamatergic System Are the Target of Guanosine Effect in Traumatic Brain Injury.

PubMed

Dobrachinski, Fernando; da Rosa Gerbatin, Rogério; Sartori, Gláubia; Ferreira Marques, Naiani; Zemolin, Ana Paula; Almeida Silva, Luiz Fernando; Franco, Jeferson Luis; Freire Royes, Luiz Fernando; Rechia Fighera, Michele; Antunes Soares, Félix Alexandre

2017-04-01

Traumatic brain injury (TBI) is a highly complex multi-factorial disorder. Experimental trauma involves primary and secondary injury cascades that underlie delayed neuronal dysfunction and death. Mitochondrial dysfunction and glutamatergic excitotoxicity are the hallmark mechanisms of damage. Accordingly, a successful pharmacological intervention requires a multi-faceted approach. Guanosine (GUO) is known for its neuromodulator effects in various models of brain pathology, specifically those that involve the glutamatergic system. The aim of the study was to investigate the GUO effects against mitochondrial damage in hippocampus and cortex of rats subjected to TBI, as well as the relationship of this effect with the glutamatergic system. Adult male Wistar rats were subjected to a unilateral moderate fluid percussion brain injury (FPI) and treated 15 min later with GUO (7.5 mg/kg) or vehicle (saline 0.9%). Analyses were performed in hippocampus and cortex 3 h post-trauma and revealed significant mitochondrial dysfunction, characterized by a disrupted membrane potential, unbalanced redox system, decreased mitochondrial viability, and complex I inhibition. Further, disruption of Ca 2+ homeostasis and increased mitochondrial swelling was also noted. Our results showed that mitochondrial dysfunction contributed to decreased glutamate uptake and levels of glial glutamate transporters (glutamate transporter 1 and glutamate aspartate transporter), which leads to excitotoxicity. GUO treatment ameliorated mitochondrial damage and glutamatergic dyshomeostasis. Thus, GUO might provide a new efficacious strategy for the treatment acute physiological alterations secondary to TBI.

Thymol, a dietary monoterpene phenol abrogates mitochondrial dysfunction in β-adrenergic agonist induced myocardial infarcted rats by inhibiting oxidative stress.

PubMed

Nagoor Meeran, M F; Jagadeesh, G S; Selvaraj, P

2016-01-25

Mitochondrial dysfunction has been suggested to be one of the important pathological events in isoproterenol (ISO), a synthetic catecholamine and β-adrenergic agonist induced myocardial infarction (MI). In this context, we have evaluated the impact of thymol against ISO induced oxidative stress and calcium uniporter malfunction involved in the pathology of mitochondrial dysfunction in rats. Male albino Wistar rats were pre and co-treated with thymol (7.5 mg/kg body weight) daily for 7 days. Isoproterenol (100 mg/kg body weight) was subcutaneously injected into rats on 6th and 7th day to induce MI. To explore the extent of cardiac mitochondrial damage, the activities/levels of cardiac marker enzymes, mitochondrial lipid peroxidation products, antioxidants, lipids, calcium, adenosine triphosphate and multi marker enzymes were evaluated. Isoproterenol induced myocardial infarcted rats showed a significant increase in the activities of cardiac diagnostic markers, heart mitochondrial lipid peroxidation, lipids, calcium, and a significant decrease in the activities/levels of heart mitochondrial superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, isocitrate, malate, α-ketoglutarate and NADH-dehydrogenases, cytochrome-C-oxidase, and adenosine triphosphate. Thymol pre and co-treatment showed near normalized effects on all the biochemical parameters studied. Transmission electron microscopic findings and mitochondrial swelling studies confirmed our biochemical findings. The in vitro study also revealed the potent free-radical scavenging activity of thymol. Thus, thymol attenuates the involvement of ISO against oxidative stress and calcium uniporter malfunction associated with mitochondrial dysfunction in rats. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Piracetam improves mitochondrial dysfunction following oxidative stress

PubMed Central

Keil, Uta; Scherping, Isabel; Hauptmann, Susanne; Schuessel, Katin; Eckert, Anne; Müller, Walter E

2005-01-01

Mitochondrial dysfunction including decrease of mitochondrial membrane potential and reduced ATP production represents a common final pathway of many conditions associated with oxidative stress, for example, hypoxia, hypoglycemia, and aging. Since the cognition-improving effects of the standard nootropic piracetam are usually more pronounced under such pathological conditions and young healthy animals usually benefit little by piracetam, the effect of piracetam on mitochondrial dysfunction following oxidative stress was investigated using PC12 cells and dissociated brain cells of animals treated with piracetam. Piracetam treatment at concentrations between 100 and 1000 μM improved mitochondrial membrane potential and ATP production of PC12 cells following oxidative stress induced by sodium nitroprusside (SNP) and serum deprivation. Under conditions of mild serum deprivation, piracetam (500 μM) induced a nearly complete recovery of mitochondrial membrane potential and ATP levels. Piracetam also reduced caspase 9 activity after SNP treatment. Piracetam treatment (100–500 mg kg−1 daily) of mice was also associated with improved mitochondrial function in dissociated brain cells. Significant improvement was mainly seen in aged animals and only less in young animals. Moreover, the same treatment reduced antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, and glutathione reductase) in aged mouse brain only, which are elevated as an adaptive response to the increased oxidative stress with aging. In conclusion, therapeutically relevant in vitro and in vivo concentrations of piracetam are able to improve mitochondrial dysfunction associated with oxidative stress and/or aging. Mitochondrial stabilization and protection might be an important mechanism to explain many of piracetam's beneficial effects in elderly patients. PMID:16284628

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

PubMed

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

2013-02-01

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

Inhibition of mitochondrial fragmentation diminishes Huntington’s disease–associated neurodegeneration

PubMed Central

Guo, Xing; Disatnik, Marie-Helene; Monbureau, Marie; Shamloo, Mehrdad; Mochly-Rosen, Daria; Qi, Xin

2013-01-01

Huntington’s disease (HD) is the result of expression of a mutated Huntingtin protein (mtHtt), and is associated with a variety of cellular dysfunctions including excessive mitochondrial fission. Here, we tested whether inhibition of excessive mitochondrial fission prevents mtHtt-induced pathology. We developed a selective inhibitor (P110-TAT) of the mitochondrial fission protein dynamin-related protein 1 (DRP1). We found that P110-TAT inhibited mtHtt-induced excessive mitochondrial fragmentation, improved mitochondrial function, and increased cell viability in HD cell culture models. P110-TAT treatment of fibroblasts from patients with HD and patients with HD with iPS cell–derived neurons reduced mitochondrial fragmentation and corrected mitochondrial dysfunction. P110-TAT treatment also reduced the extent of neurite shortening and cell death in iPS cell–derived neurons in patients with HD. Moreover, treatment of HD transgenic mice with P110-TAT reduced mitochondrial dysfunction, motor deficits, neuropathology, and mortality. We found that p53, a stress gene involved in HD pathogenesis, binds to DRP1 and mediates DRP1-induced mitochondrial and neuronal damage. Furthermore, P110-TAT treatment suppressed mtHtt-induced association of p53 with mitochondria in multiple HD models. These data indicate that inhibition of DRP1-dependent excessive mitochondrial fission with a P110-TAT–like inhibitor may prevent or slow the progression of HD. PMID:24231356

Impaired Cerebral Mitochondrial Oxidative Phosphorylation Function in a Rat Model of Ventricular Fibrillation and Cardiopulmonary Resuscitation

PubMed Central

Fu, Yue; Xu, Wen; Jiang, Longyuan; Huang, Zitong

2014-01-01

Postcardiac arrest brain injury significantly contributes to mortality and morbidity in patients suffering from cardiac arrest (CA). Evidence that shows that mitochondrial dysfunction appears to be a key factor in tissue damage after ischemia/reperfusion is accumulating. However, limited data are available regarding the cerebral mitochondrial dysfunction during CA and cardiopulmonary resuscitation (CPR) and its relationship to the alterations of high-energy phosphate. Here, we sought to identify alterations of mitochondrial morphology and oxidative phosphorylation function as well as high-energy phosphates during CA and CPR in a rat model of ventricular fibrillation (VF). We found that impairment of mitochondrial respiration and partial depletion of adenosine triphosphate (ATP) and phosphocreatine (PCr) developed in the cerebral cortex and hippocampus following a prolonged cardiac arrest. Optimal CPR might ameliorate the deranged phosphorus metabolism and preserve mitochondrial function. No obvious ultrastructural abnormalities of mitochondria have been found during CA. We conclude that CA causes cerebral mitochondrial dysfunction along with decay of high-energy phosphates, which would be mitigated with CPR. This study may broaden our understanding of the pathogenic processes underlying global cerebral ischemic injury and provide a potential therapeutic strategy that aimed at preserving cerebral mitochondrial function during CA. PMID:24696844

Mitochondrial dysfunction-associated OPA1 cleavage contributes to muscle degeneration: preventative effect of hydroxytyrosol acetate.

PubMed

Wang, X; Li, H; Zheng, A; Yang, L; Liu, J; Chen, C; Tang, Y; Zou, X; Li, Y; Long, J; Liu, J; Zhang, Y; Feng, Z

2014-11-13

Mitochondrial dysfunction contributes to the development of muscle disorders, including muscle wasting, muscle atrophy and degeneration. Despite the knowledge that oxidative stress closely interacts with mitochondrial dysfunction, the detailed mechanisms remain obscure. In this study, tert-butylhydroperoxide (t-BHP) was used to induce oxidative stress on differentiated C2C12 myotubes. t-BHP induced significant mitochondrial dysfunction in a time-dependent manner, accompanied by decreased myosin heavy chain (MyHC) expression at both the mRNA and protein levels. Consistently, endogenous reactive oxygen species (ROS) overproduction triggered by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), a mitochondrial oxidative phosphorylation inhibitor, was accompanied by decreased membrane potential and decreased MyHC protein content. However, the free radical scavenger N-acetyl-L-cysteine (NAC) efficiently reduced the ROS level and restored MyHC content, suggesting a close association between ROS and MyHC expression. Meanwhile, we found that both t-BHP and FCCP promoted the cleavage of optic atrophy 1 (OPA1) from the long form into short form during the early stages. In addition, the ATPase family gene 3-like 2, a mitochondrial inner membrane protease, was also markedly increased. Moreover, OPA1 knockdown in myotubes was accompanied by decreased MyHC content, whereas NAC failed to prevent FCCP-induced MyHC decrease with OPA1 knockdown, suggesting that ROS might affect MyHC content by modulating OPA1 cleavage. In addition, hydroxytyrosol acetate (HT-AC), an important compound in virgin olive oil, could significantly prevent t-BHP-induced mitochondrial membrane potential and cell viability loss in myotubes. Specifically, HT-AC inhibited t-BHP-induced OPA1 cleavage and mitochondrial morphology changes, accompanied by improvement on mitochondrial oxygen consumption capacity, ATP productive potential and activities of mitochondrial complex I, II and V. Moreover, both t-BHP- and FCCP-induced MyHC decrease was sufficiently inhibited by HT-AC. Taken together, our data provide evidence indicating that mitochondrial dysfunction-associated OPA1 cleavage may contribute to muscle degeneration, and olive oil compounds could be effective nutrients for preventing the development of muscle disorders.

Oxalate induces mitochondrial dysfunction and disrupts redox homeostasis in a human monocyte derived cell line.

PubMed

Patel, Mikita; Yarlagadda, Vidhush; Adedoyin, Oreoluwa; Saini, Vikram; Assimos, Dean G; Holmes, Ross P; Mitchell, Tanecia

2018-05-01

Monocytes/macrophages are thought to be recruited to the renal interstitium during calcium oxalate (CaOx) kidney stone disease for crystal clearance. Mitochondria play an important role in monocyte function during the immune response. We recently determined that monocytes in patients with CaOx kidney stones have decreased mitochondrial function compared to healthy subjects. The objective of this study was to determine whether oxalate, a major constituent found in CaOx kidney stones, alters cell viability, mitochondrial function, and redox homeostasis in THP-1 cells, a human derived monocyte cell line. THP-1 cells were treated with varying concentrations of CaOx crystals (insoluble form) or sodium oxalate (NaOx; soluble form) for 24h. In addition, the effect of calcium phosphate (CaP) and cystine crystals was tested. CaOx crystals decreased cell viability and induced mitochondrial dysfunction and redox imbalance in THP-1 cells compared to control cells. However, NaOx only caused mitochondrial damage and redox imbalance in THP-1 cells. In contrast, both CaP and cystine crystals did not affect THP-1 cells. Separate experiments showed that elevated oxalate also induced mitochondrial dysfunction in primary monocytes from healthy subjects. These findings suggest that oxalate may play an important role in monocyte mitochondrial dysfunction in CaOx kidney stone disease. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Myopathic involvement and mitochondrial pathology in Kennedy disease and in other motor neuron diseases.

PubMed

Orsucci, D; Rocchi, A; Caldarazzo Ienco, E; Alì, G; LoGerfo, A; Petrozzi, L; Scarpelli, M; Filosto, M; Carlesi, C; Siciliano, G; Bonuccelli, U; Mancuso, M

2014-01-01

Kennedy disease (spinal and bulbar muscular atrophy, or SBMA) is a motor neuron disease caused by a CAG expansion in the androgen-receptor (AR) gene. Increasing evidence shows that SBMA may have a primary myopathic component and that mitochondrial dysfunction may have some role in the pathogenesis of this disease. In this article, we review the role of mitochondrial dysfunction and of the mitochondrial genome (mtDNA) in SBMA, and we present the illustrative case of a patient who presented with increased CK levels and exercise intolerance. Molecular analysis led to definitive diagnosis of SBMA, whereas muscle biopsy showed a mixed myopathic and neurogenic process with "mitochondrial features" and multiple mtDNA deletions, supporting some role of mitochondria in the pathogenesis of the myopathic component of Kennedy disease. Furthermore, we briefly review the role of mitochondrial dysfunction in two other motor neuron diseases (namely spinal muscular atrophy and amyotrophic lateral sclerosis). Most likely, in most cases mtDNA does not play a primary role and it is involved subsequently. MtDNA deletions may contribute to the neurodegenerative process, but the exact mechanisms are still unclear. It will be important to develop a better understanding of the role of mitochondrial dysfunction in motoneuron diseases, since it may lead to the development of more effective strategies for the treatment of this devastating disorder.

Blockade of Drp1 rescues oxidative stress-induced osteoblast dysfunction

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

Gan, Xueqi; Huang, Shengbin; Yu, Qing

Osteoblast dysfunction, induced by oxidative stress, plays a critical role in the pathophysiology of osteoporosis. However, the underlying mechanisms remain unclarified. Imbalance of mitochondrial dynamics has been closely linked to oxidative stress. Here, we reveal an unexplored role of dynamic related protein 1(Drp1), the major regulator in mitochondrial fission, in the oxidative stress-induced osteoblast injury model. We demonstrate that levels of phosphorylation and expression of Drp1 significantly increased under oxidative stress. Blockade of Drp1, through pharmaceutical inhibitor or gene knockdown, significantly protected against H{sub 2}O{sub 2}-induced osteoblast dysfunction, as shown by increased cell viability, improved cellular alkaline phosphatase (ALP) activitymore » and mineralization and restored mitochondrial function. The protective effects of blocking Drp1 in H{sub 2}O{sub 2}-induced osteoblast dysfunction were evidenced by increased mitochondrial function and suppressed production of reactive oxygen species (ROS). These findings provide new insights into the role of the Drp1-dependent mitochondrial pathway in the pathology of osteoporosis, indicating that the Drp1 pathway may be targetable for the development of new therapeutic approaches in the prevention and the treatment of osteoporosis. - Highlights: • Oxidative stress is an early pathological event in osteoporosis. • Imbalance of mitochondrial dynamics are linked to oxidative stress in osteoporosis. • The role of the Drp1-dependent mitochondrial pathway in osteoporosis.« less

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

PubMed Central

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

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

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

PubMed

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

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

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells.

PubMed

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi; Ren, Yanming; Yu, Haiyang; You, Chao

2017-01-29

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics in oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial 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.

Fatty acid ethyl ester synthase inhibition ameliorates ethanol-induced Ca2+-dependent mitochondrial dysfunction and acute pancreatitis

PubMed Central

Huang, Wei; Booth, David M; Cane, Matthew C; Chvanov, Michael; Javed, Muhammad A; Elliott, Victoria L; Armstrong, Jane A; Dingsdale, Hayley; Cash, Nicole; Li, Yan; Greenhalf, William; Mukherjee, Rajarshi; Kaphalia, Bhupendra S; Jaffar, Mohammed; Petersen, Ole H; Tepikin, Alexei V; Sutton, Robert; Criddle, David N

2014-01-01

Objective Non-oxidative metabolism of ethanol (NOME) produces fatty acid ethyl esters (FAEEs) via carboxylester lipase (CEL) and other enzyme action implicated in mitochondrial injury and acute pancreatitis (AP). This study investigated the relative importance of oxidative and non-oxidative pathways in mitochondrial dysfunction, pancreatic damage and development of alcoholic AP, and whether deleterious effects of NOME are preventable. Design Intracellular calcium ([Ca2+]C), NAD(P)H, mitochondrial membrane potential and activation of apoptotic and necrotic cell death pathways were examined in isolated pancreatic acinar cells in response to ethanol and/or palmitoleic acid (POA) in the presence or absence of 4-methylpyrazole (4-MP) to inhibit oxidative metabolism. A novel in vivo model of alcoholic AP induced by intraperitoneal administration of ethanol and POA was developed to assess the effects of manipulating alcohol metabolism. Results Inhibition of OME with 4-MP converted predominantly transient [Ca2+]C rises induced by low ethanol/POA combination to sustained elevations, with concurrent mitochondrial depolarisation, fall of NAD(P)H and cellular necrosis in vitro. All effects were prevented by 3-benzyl-6-chloro-2-pyrone (3-BCP), a CEL inhibitor. 3-BCP also significantly inhibited rises of pancreatic FAEE in vivo and ameliorated acute pancreatic damage and inflammation induced by administration of ethanol and POA to mice. Conclusions A combination of low ethanol and fatty acid that did not exert deleterious effects per se became toxic when oxidative metabolism was inhibited. The in vitro and in vivo damage was markedly inhibited by blockade of CEL, indicating the potential for development of specific therapy for treatment of alcoholic AP via inhibition of FAEE generation. PMID:24162590

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.

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

PubMed

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

2007-01-01

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

Yeast as a system for modeling mitochondrial disease mechanisms and discovering therapies

PubMed Central

Lasserre, Jean-Paul; Dautant, Alain; Aiyar, Raeka S.; Kucharczyk, Roza; Glatigny, Annie; Tribouillard-Tanvier, Déborah; Rytka, Joanna; Blondel, Marc; Skoczen, Natalia; Reynier, Pascal; Pitayu, Laras; Rötig, Agnès; Delahodde, Agnès; Steinmetz, Lars M.; Dujardin, Geneviève; Procaccio, Vincent; di Rago, Jean-Paul

2015-01-01

ABSTRACT Mitochondrial diseases are severe and largely untreatable. Owing to the many essential processes carried out by mitochondria and the complex cellular systems that support these processes, these diseases are diverse, pleiotropic, and challenging to study. Much of our current understanding of mitochondrial function and dysfunction comes from studies in the baker's yeast Saccharomyces cerevisiae. Because of its good fermenting capacity, S. cerevisiae can survive mutations that inactivate oxidative phosphorylation, has the ability to tolerate the complete loss of mitochondrial DNA (a property referred to as ‘petite-positivity’), and is amenable to mitochondrial and nuclear genome manipulation. These attributes make it an excellent model system for studying and resolving the molecular basis of numerous mitochondrial diseases. Here, we review the invaluable insights this model organism has yielded about diseases caused by mitochondrial dysfunction, which ranges from primary defects in oxidative phosphorylation to metabolic disorders, as well as dysfunctions in maintaining the genome or in the dynamics of mitochondria. Owing to the high level of functional conservation between yeast and human mitochondrial genes, several yeast species have been instrumental in revealing the molecular mechanisms of pathogenic human mitochondrial gene mutations. Importantly, such insights have pointed to potential therapeutic targets, as have genetic and chemical screens using yeast. PMID:26035862

Real-time monitoring of metabolic function in liver-on-chip microdevices tracks the dynamics of mitochondrial dysfunction

PubMed Central

Bavli, Danny; Prill, Sebastian; Ezra, Elishai; Levy, Gahl; Cohen, Merav; Vinken, Mathieu; Vanfleteren, Jan; Jaeger, Magnus; Nahmias, Yaakov

2016-01-01

Microfluidic organ-on-a-chip technology aims to replace animal toxicity testing, but thus far has demonstrated few advantages over traditional methods. Mitochondrial dysfunction plays a critical role in the development of chemical and pharmaceutical toxicity, as well as pluripotency and disease processes. However, current methods to evaluate mitochondrial activity still rely on end-point assays, resulting in limited kinetic and prognostic information. Here, we present a liver-on-chip device capable of maintaining human tissue for over a month in vitro under physiological conditions. Mitochondrial respiration was monitored in real time using two-frequency phase modulation of tissue-embedded phosphorescent microprobes. A computer-controlled microfluidic switchboard allowed contiguous electrochemical measurements of glucose and lactate, providing real-time analysis of minute shifts from oxidative phosphorylation to anaerobic glycolysis, an early indication of mitochondrial stress. We quantify the dynamics of cellular adaptation to mitochondrial damage and the resulting redistribution of ATP production during rotenone-induced mitochondrial dysfunction and troglitazone (Rezulin)-induced mitochondrial stress. We show troglitazone shifts metabolic fluxes at concentrations previously regarded as safe, suggesting a mechanism for its observed idiosyncratic effect. Our microfluidic platform reveals the dynamics and strategies of cellular adaptation to mitochondrial damage, a unique advantage of organ-on-chip technology. PMID:27044092

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells

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

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics inmore » oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. - Highlights: • Demonstrated first time the link between the mPTP to mitochondrial dynamics. • The role of Cyclophilin D in the regulation of Drp1-mediated mitochondrial fission. • CsA as a potential target for governing oxidative stress related neuropathology.« less

Oxygen matters: tissue culture oxygen levels affect mitochondrial function and structure as well as responses to HIV viroproteins.

PubMed

Tiede, L M; Cook, E A; Morsey, B; Fox, H S

2011-12-22

Mitochondrial dysfunction is implicated in a majority of neurodegenerative disorders and much study of neurodegenerative disease is done on cultured neurons. In traditional tissue culture, the oxygen level that cells experience is dramatically higher (21%) than in vivo conditions (1-11%). These differences can alter experimental results, especially, pertaining to mitochondria and oxidative metabolism. Our results show that primary neurons cultured at physiological oxygen levels found in the brain showed higher polarization, lower rates of ROS production, larger mitochondrial networks, greater cytoplasmic fractions of mitochondria and larger mitochondrial perimeters than those cultured at higher oxygen levels. Although neurons cultured in either physiological oxygen or atmospheric oxygen exhibit significant increases in mitochondrial reactive oxygen species (ROS) production when treated with the human immunodeficiency virus (HIV) virotoxin trans-activator of transcription, mitochondria of neurons cultured at physiological oxygen underwent depolarization with dramatically increased cell death, whereas those cultured at atmospheric oxygen became hyperpolarized with no increase in cell death. Studies with a second HIV virotoxin, negative regulation factor (Nef), revealed that Nef treatment also increased mitochondrial ROS production for both the oxygen conditions, but resulted in mitochondrial depolarization and increased death only in neurons cultured in physiological oxygen. These results indicate a role for oxidative metabolism in a mechanism of neurotoxicity during HIV infection and demonstrate the importance of choosing the correct, physiological, culture oxygen in mitochondrial studies performed in neurons.

Mitochondrial Dysfunction and Disturbed Coherence: Gate to Cancer

PubMed Central

Pokorný, Jiří; Pokorný, Jan; Foletti, Alberto; Kobilková, Jitka; Vrba, Jan; Vrba, Jan

2015-01-01

Continuous energy supply, a necessary condition for life, excites a state far from thermodynamic equilibrium, in particular coherent electric polar vibrations depending on water ordering in the cell. Disturbances in oxidative metabolism and coherence are a central issue in cancer development. Oxidative metabolism may be impaired by decreased pyruvate transfer to the mitochondrial matrix, either by parasitic consumption and/or mitochondrial dysfunction. This can in turn lead to disturbance in water molecules’ ordering, diminished power, and coherence of the electromagnetic field. In tumors with the Warburg (reverse Warburg) effect, mitochondrial dysfunction affects cancer cells (fibroblasts associated with cancer cells), and the electromagnetic field generated by microtubules in cancer cells has low power (high power due to transport of energy-rich metabolites from fibroblasts), disturbed coherence, and a shifted frequency spectrum according to changed power. Therapeutic strategies restoring mitochondrial function may trigger apoptosis in treated cells; yet, before this step is performed, induction (inhibition) of pyruvate dehydrogenase kinases (phosphatases) may restore the cancer state. In tumor tissues with the reverse Warburg effect, Caveolin-1 levels should be restored and the transport of energy-rich metabolites interrupted to cancer cells. In both cancer phenotypes, achieving permanently reversed mitochondrial dysfunction with metabolic-modulating drugs may be an effective, specific anti-cancer strategy. PMID:26437417

The perfect storm: obesity, adipocyte dysfunction, and metabolic consequences.

PubMed

de Ferranti, Sarah; Mozaffarian, Dariush

2008-06-01

As the prevalence of adiposity soars in both developed and developing nations, appreciation of the close links between obesity and disease increases. The strong relationships between excess adipose tissue and poor health outcomes, including cardiovascular disease, diabetes, and cancer, mandate elucidation of the complex cellular, hormonal, and molecular pathophysiology whereby adiposity initiates and maintains adverse health effects. In this report we review adipocyte metabolism and function in the context of energy imbalance and postprandial nutrient excess, including adipocyte hypertrophy and hyperplasia, adipocyte dysfunction, and other systemic consequences. We also discuss implications for laboratory evaluation and clinical care, including the role of lifestyle modifications. Chronic energy imbalance produces adipocyte hypertrophy and hyperplasia, endoplasmic reticulum stress, and mitochondrial dysfunction. These processes lead to increased intracellular and systemic release of adipokines, free fatty acids, and inflammatory mediators that cause adipocyte dysfunction and induce adverse effects in the liver, pancreatic beta-cells, and skeletal muscle as well as the heart and vascular beds. Several specialized laboratory tests can quantify these processes and predict clinical risk, but translation to the clinical setting is premature. Current and future pharmacologic interventions may target these pathways; modest changes in diet, physical activity, weight, and smoking are likely to have the greatest impact. Adipocyte endoplasmic reticulum and mitochondrial stress, and associated changes in circulating adipokines, free fatty acids, and inflammatory mediators, are central to adverse health effects of adiposity. Future investigation should focus on these pathways and on reversing the adverse lifestyle behaviors that are the fundamental causes of adiposity.

Adult-onset of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome with hypothyroidism and psychiatric disorders.

PubMed

Ge, Yu-Xing; Shang, Bo; Chen, Wen-Zhen; Lu, You; Wang, Jue

2017-03-01

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a clinical syndrome associated with mitochondrial disorders (MIDs). This report illustrates a case of MELAS syndrome with hypothyroidism and psychiatric disorders, which is different from the common clinical manifestations of MELAS syndrome, such as exercise intolerance, migraine-like headaches, hearing loss and seizures etc. There are considerable interests in the possibility that mitochondrial dysfunction may play a role in the pathogenesis of endocrine dysfunctions and psychiatric disorders in MELAS syndrome.

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.

Perspectives of drug-based neuroprotection targeting mitochondria.

PubMed

Procaccio, V; Bris, C; Chao de la Barca, J M; Oca, F; Chevrollier, A; Amati-Bonneau, P; Bonneau, D; Reynier, P

2014-05-01

Mitochondrial dysfunction has been reported in most neurodegenerative diseases. These anomalies include bioenergetic defect, respiratory chain-induced oxidative stress, defects of mitochondrial dynamics, increase sensitivity to apoptosis, and accumulation of damaged mitochondria with instable mitochondrial DNA. Significant progress has been made in our understanding of the pathophysiology of inherited mitochondrial disorders but most have no effective therapies. The development of new metabolic treatments will be useful not only for rare mitochondrial disorders but also for the wide spectrum of common age-related neurodegenerative diseases shown to be associated with mitochondrial dysfunction. A better understanding of the mitochondrial regulating pathways raised several promising perspectives of neuroprotection. This review focuses on the pharmacological approaches to modulate mitochondrial biogenesis, the removal of damaged mitochondria through mitophagy, scavenging free radicals and also dietary measures such as ketogenic diet. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Mitochondria, Cybrids, Aging, and Alzheimer’s Disease

PubMed Central

Swerdlow, Russell H.; Koppel, Scott; Weidling, Ian; Hayley, Clay; Ji, Yan; Wilkins, Heather M.

2018-01-01

Mitochondrial and bioenergetic function change with advancing age and may drive aging phenotypes. Mitochondrial and bioenergetic changes are also documented in various age-related neurodegenerative diseases, including Alzheimer’s disease (AD). In some instances AD mitochondrial and bioenergetic changes are reminiscent of those observed with advancing age, but are greater in magnitude. Mitochondrial and bioenergetic dysfunction could, therefore, link neurodegeneration to brain aging. Interestingly, mitochondrial defects in AD patients are not brain-limited, and mitochondrial function can be linked to classic AD histologic changes including amyloid precursor protein processing to beta amyloid. Also, transferring mitochondria from AD subjects to cell lines depleted of endogenous mitochondrial DNA (mtDNA) creates cytoplasmic hybrid (cybrid) cell lines that recapitulate specific biochemical, molecular, and histologic AD features. Such findings have led to the formulation of a “mitochondrial cascade hypothesis” that places mitochondrial dysfunction at the apex of the AD pathology pyramid. Data pertinent to this premise are reviewed. PMID:28253988

Mitochondrial impairments contribute to spatial learning and memory dysfunction induced by chronic tramadol administration in rat: Protective effect of physical exercise.

PubMed

Mehdizadeh, Hajar; Pourahmad, Jalal; Taghizadeh, Ghorban; Vousooghi, Nasim; Yoonessi, Ali; Naserzadeh, Parvaneh; Behzadfar, Ladan; Rouini, Mohammad Reza; Sharifzadeh, Mohammad

2017-10-03

Despite the worldwide use of tramadol, few studies have been conducted about its effects on memory and mitochondrial function, and controversial results have been reported. Recently, there has been an increasing interest in physical exercise as a protective approach to neuronal and cognitive impairments. Therefore, the aim of this study was to investigate the effects of physical exercise on spatial learning and memory and brain mitochondrial function in tramadol-treated rats. After completion of 2-week (short-term) and 4-week (long-term) treadmill exercise regimens, male Wistar rats received tramadol (20, 40, 80mg/kg/day) intraperitoneally for 30days. Then spatial learning and memory was assessed by Morris water maze test (MWM). Moreover, brain mitochondrial function was evaluated by determination of mitochondrial reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP), mitochondrial swelling and cytochrome c release from mitochondria. Chronic administration of tramadol impaired spatial learning and memory as well as brain mitochondrial function as indicated by increased ROS level, MMP collapse, increased mitochondrial swelling and cytochrome c release from mitochondria. Conversely, treadmill exercise significantly attenuated the impairments of spatial learning and memory and brain mitochondrial dysfunction induced by tramadol. The results revealed that chronic tramadol treatment caused memory impairments through induction of brain mitochondrial dysfunction. Furthermore, pre-exposure to physical exercise markedly mitigated these impairments through its positive effects on brain mitochondrial function. Copyright © 2017. Published by Elsevier Inc.

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

PubMed

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

2017-01-01

The feeding of alcohol orally (Lieber-DeCarli diet) to rats has been shown to cause declines in mitochondrial respiration (state III), decreased expression of respiratory complexes, and decreased respiratory control ratios (RCR) in liver mitochondria. These declines and other mitochondrial alterations have led to the hypothesis that alcohol feeding causes "mitochondrial dysfunction" in the liver. If oral alcohol feeding leads to mitochondrial dysfunction, one would predict that increasing alcohol delivery by intragastric (IG) alcohol feeding to rats would cause greater declines in mitochondrial bioenergetics in the liver. In this study, we examined the mitochondrial alterations that occur in rats fed alcohol both orally and intragastrically. Oral alcohol feeding decreased glutamate/malate-, acetaldehyde- and succinate-driven state III respiration, RCR, and expression of respiratory complexes (I, III, IV, V) in liver mitochondria, in agreement with previous results. IG alcohol feeding, on the other hand, caused a slight increase in glutamate/malate-driven respiration, and significantly increased acetaldehyde-driven respiration in liver mitochondria. IG feeding also caused liver mitochondria to experience a decline in succinate-driven respiration, but these decreases were smaller than those observed with oral alcohol feeding. Surprisingly, oral and IG alcohol feeding to rats increased mitochondrial respiration using other substrates, including glycerol-3-phosphate (which delivers electrons from cytoplasmic NADH to mitochondria) and octanoate (a substrate for beta-oxidation). The enhancement of glycerol-3-phosphate- and octanoate-driven respiration suggests that liver mitochondria remodeled in response to alcohol feeding. In support of this notion, we observed that IG alcohol feeding also increased expression of mitochondrial glycerol phosphate dehydrogenase-2 (GPD2), transcription factor A (TFAM), and increased mitochondrial NAD + -NADH and NADP + -NADPH levels in the liver. Our findings suggest that mitochondrial dysfunction represents an incomplete picture of mitochondrial dynamics that occur in the liver following alcohol feeding. While alcohol feeding causes some mitochondrial dysfunction (i.e. succinate-driven respiration), our work suggests that the major consequence of alcohol feeding is mitochondrial remodeling in the liver as an adaptation. This mitochondrial remodeling may play an important role in the enhanced alcohol metabolism and other adaptations in the liver that develop with alcohol intake. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial dysfunction as a trigger of innate immune responses and inflammation.

PubMed

West, A Phillip

2017-11-01

A growing literature indicates that mitochondria are key participants in innate immune pathways, functioning as both signaling platforms and contributing to effector responses. In addition to regulating antiviral signaling and antibacterial immunity, mitochondria are also important drivers of inflammation caused by sterile injury. Much research on mitochondrial control of immunity now centers on understanding how mitochondrial constituents released during cellular damage simulate the innate immune system. When mitochondrial integrity is compromised, mitochondrial damage-associated molecular patterns engage pattern recognition receptors, trigger inflammation, and promote pathology in an expanding list of diseases. Here, I review the emerging knowledge of mitochondrial dysfunction in innate immune responses and discuss how environmental exposures may induce mitochondrial damage to potentiate inflammation and human disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Ursolic acid improves domoic acid-induced cognitive deficits in mice

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

Wu, Dong-mei; Key Laboratory for Biotechnology on Medicinal Plants of Jiangsu Province, School of Life Science, Xuzhou Normal University, Xuzhou 221116, Jiangsu Province; Lu, Jun, E-mail: lu-jun75@163.com

Our previous findings suggest that mitochondrial dysfunction is the mechanism underlying cognitive deficits induced by domoic acid (DA). Ursolic acid (UA), a natural triterpenoid compound, possesses many important biological functions. Evidence shows that UA can activate PI3K/Akt signaling and suppress Forkhead box protein O1 (FoxO1) activity. FoxO1 is an important regulator of mitochondrial function. Here we investigate whether FoxO1 is involved in the oxidative stress-induced mitochondrial dysfunction in DA-treated mice and whether UA inhibits DA-induced mitochondrial dysfunction and cognitive deficits through regulating the PI3K/Akt and FoxO1 signaling pathways. Our results showed that FoxO1 knockdown reversed the mitochondrial abnormalities and cognitivemore » deficits induced by DA in mice through decreasing HO-1 expression. Mechanistically, FoxO1 activation was associated with oxidative stress-induced JNK activation and decrease of Akt phosphorylation. Moreover, UA attenuated the mitochondrial dysfunction and cognitive deficits through promoting Akt phosphorylation and FoxO1 nuclear exclusion in the hippocampus of DA-treated mice. LY294002, an inhibitor of PI3K/Akt signaling, significantly decreased Akt phosphorylation in the hippocampus of DA/UA mice, which weakened UA actions. These results suggest that UA could be recommended as a possible candidate for the prevention and therapy of cognitive deficits in excitotoxic brain disorders. - Highlights: • Ursolic acid (UA) is a naturally triterpenoid compound. • UA attenuated the mitochondrial dysfunction and cognitive deficits. • Mechanistically, UA activates PI3K/Akt signaling and suppresses FoxO1 activity. • UA could be recommended as a possible candidate for anti-excitotoxic brain disorders.« less

BDNF pathway is involved in the protective effects of SS-31 on isoflurane-induced cognitive deficits in aging mice.

PubMed

Wu, Jing; Zhang, Mingqiang; Li, Huihui; Sun, Xiaoru; Hao, Shuangying; Ji, Muhuo; Yang, Jianjun; Li, Kuanyu

2016-05-15

Mitochondrial dysfunction has been linked to the earliest pathogenesis of isoflurane-induced cognitive impairments in developing or aging mammalian brain. However, its molecular mechanism is poorly understood and a pharmacologic treatment to rapidly reverse mitochondrial dysfunction is lacking. Fifteen-month-old male C57BL/6 mice were exposed to isoflurane for two hours following intraperitoneal administration of mitochondrion-targeted peptide SS-31 or vehicle with 30min interval. The hippocampus was immediately removed for biochemical assays and mitochondria isolation after inhalation. Behavioral tests were evaluated by the open field test and fear conditioning test 24h after the experiment. We showed that cognitive deficits induced by exposure of the aging mice to isoflurane were accompanied by mitochondrial dysfunction in hippocampus due to loss of the enzymatic activity of complex I. This loss resulted in the increase of reactive oxygen species production, decrease of ATP production and mitochondrial membrane potential, and opening of mitochondrial permeability transition pore. Further, we provided evidence that the BDNF signaling pathway was involved in this process to regulate synaptic plasticity-related proteins, for instance, downregulation of synapsin 1, PSD-95 and p-CREB, and upregulation of NR2A, NR2B, CaMKIIα and CaMKIIβ. Of note, the isoflurane-induced cognitive deficits were rescued by SS-31 through reversal of mitochondrial dysfunction, which facilitated the regulation of BDNF signaling including the expression reversal of aforementioned important synaptic-signaling proteins in aging mice. Our data demonstrate that reversing mitochondrial dysfunction by SS-31 enhances BDNF signaling pathway and synaptic plasticity, and provides protective effects on cognitive function, thereby support the notion that SS-31 may have therapeutic benefits for elderly humans undertaking anesthesia. Copyright © 2016 Elsevier B.V. All rights reserved.

Early mitochondrial dysfunction in glycolytic muscle, but not oxidative muscle, of the fructose-fed insulin-resistant rat

PubMed Central

Warren, Blair E.; Lou, Phing-How; Lucchinetti, Eliana; Zhang, Liyan; Clanachan, Alexander S.; Affolter, Andreas; Hersberger, Martin; Zaugg, Michael

2014-01-01

Although evidence that type 2 diabetes mellitus (T2DM) is accompanied by mitochondrial dysfunction in skeletal muscle has been accumulating, a causal link between mitochondrial dysfunction and the pathogenesis of the disease remains unclear. Our study focuses on an early stage of the disease to determine whether mitochondrial dysfunction contributes to the development of T2DM. The fructose-fed (FF) rat was used as an animal model of early T2DM. Mitochondrial respiration and acylcarnitine species were measured in oxidative (soleus) and glycolytic [extensor digitorum longus (EDL)] muscle. Although FF rats displayed characteristic signs of T2DM, including hyperglycemia, hyperinsulinemia, and hypertriglyceridemia, mitochondrial content was preserved in both muscles from FF rats. The EDL muscle had reduced complex I and complex I and II respiration in the presence of pyruvate but not glutamate. The decrease in pyruvate-supported respiration was due to a decrease in pyruvate dehydrogenase activity. Accumulation of C14:1 and C14:2 acylcarnitine species and a decrease in respiration supported by long-chain acylcarnitines but not acetylcarnitine indicated dysfunctional β-oxidation in the EDL muscle. In contrast, the soleus muscle showed preserved mitochondrial respiration, pyruvate dehydrogenase activity, and increased fatty acid oxidation, as evidenced by overall reduced acylcarnitine levels. Aconitase activity, a sensitive index of reactive oxygen species production in mitochondria, was reduced exclusively in EDL muscle, which showed lower levels of the antioxidant enzymes thioredoxin reductase and glutathione peroxidase. Here, we show that the glycolytic EDL muscle is more prone to an imbalance between energy supply and oxidation caused by insulin resistance than the oxidative soleus muscle. PMID:24425766

Celastrol attenuates mitochondrial dysfunction and inflammation in palmitate-mediated insulin resistance in C3A hepatocytes.

PubMed

Abu Bakar, Mohamad Hafizi; Sarmidi, Mohamad Roji; Tan, Joo Shun; Mohamad Rosdi, Mohamad Norisham

2017-03-15

Accumulating evidence indicates that mitochondrial dysfunction-induced inflammation is among the convergence points for the greatest hallmarks of hepatic insulin resistance. Celastrol, an anti-inflammatory compound from the root of Tripterygium Wilfordii has been reported to mitigate insulin resistance and inflammation in animal disease models. Nevertheless, the specific mechanistic actions of celastrol in modulating such improvements at the cellular level remain obscure. The present study sought to explore the mechanistic roles of celastrol upon insulin resistance induced by palmitate in C3A human hepatocytes. The hepatocytes exposed to palmitate (0.75mM) for 48h exhibited reduced both basal and insulin-stimulated glucose uptake, mitochondrial dysfunction, leading to increased mitochondrial oxidative stress with diminished fatty acid oxidation. Elevated expressions of nuclear factor-kappa B p65 (NF-κB p65), c-Jun NH(2)-terminal kinase (JNK) signaling pathways and the amplified release of pro-inflammatory cytokines including IL-8, IL-6, TNF-α and CRP were observed following palmitate treatment. Consistently, palmitate reduced and augmented phosphorylated Tyrosine-612 and Serine-307 of insulin receptor substrate-1 (IRS-1) proteins, respectively in hepatocytes. However, celastrol at the optimum concentration of 30nM was able to reverse these deleterious occasions and protected the cells from mitochondrial dysfunction and insulin resistance. Importantly, we presented evidence for the first time that celastrol efficiently prevented palmitate-induced insulin resistance in hepatocytes at least, via improved mitochondrial functions and insulin signaling pathways. In summary, the present investigation underlines a conceivable mechanism to elucidate the cytoprotective potential of celastrol in attenuating mitochondrial dysfunction and inflammation against the development of hepatic insulin resistance. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel diagnostic tool reveals mitochondrial pathology in human diseases and aging.

PubMed

Scheibye-Knudsen, Morten; Scheibye-Alsing, Karsten; Canugovi, Chandrika; Croteau, Deborah L; Bohr, Vilhelm A

2013-03-01

The inherent complex and pleiotropic phenotype of mitochondrial diseases poses a significant diagnostic challenge for clinicians as well as an analytical barrier for scientists. To overcome these obstacles we compiled a novel database, www.mitodb.com, containing the clinical features of primary mitochondrial diseases. Based on this we developed a number of qualitative and quantitative measures, enabling us to determine whether a disorder can be characterized as mitochondrial. These included a clustering algorithm, a disease network, a mitochondrial barcode and two scoring algorithms. Using these tools we detected mitochondrial involvement in a number of diseases not previously recorded as mitochondrial. As a proof of principle Cockayne syndrome, ataxia with oculomotor apraxia 1 (AOA1), spinocerebellar ataxia with axonal neuropathy 1 (SCAN1) and ataxia-telangiectasia have recently been shown to have mitochondrial dysfunction and those diseases showed strong association with mitochondrial disorders. We next evaluated mitochondrial involvement in aging and detected two distinct categories of accelerated aging disorders, one of them being associated with mitochondrial dysfunction. Normal aging seemed to associate stronger with the mitochondrial diseases than the non-mitochondrial partially supporting a mitochondrial theory of aging.

Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model.

PubMed

Komulainen, Tuomas; Lodge, Tiffany; Hinttala, Reetta; Bolszak, Maija; Pietilä, Mika; Koivunen, Peppi; Hakkola, Jukka; Poulton, Joanna; Morten, Karl J; Uusimaa, Johanna

2015-05-04

Sodium valproate (VPA) is a potentially hepatotoxic antiepileptic drug. Risk of VPA-induced hepatotoxicity is increased in patients with mitochondrial diseases and especially in patients with POLG1 gene mutations. We used a HepG2 cell in vitro model to investigate the effect of VPA on mitochondrial activity. Cells were incubated in glucose medium and mitochondrial respiration-inducing medium supplemented with galactose and pyruvate. VPA treatments were carried out at concentrations of 0-2.0mM for 24-72 h. In both media, VPA caused decrease in oxygen consumption rates and mitochondrial membrane potential. VPA exposure led to depleted ATP levels in HepG2 cells incubated in galactose medium suggesting dysfunction in mitochondrial ATP production. In addition, VPA exposure for 72 h increased levels of mitochondrial reactive oxygen species (ROS), but adversely decreased protein levels of mitochondrial superoxide dismutase SOD2, suggesting oxidative stress caused by impaired elimination of mitochondrial ROS and a novel pathomechanism related to VPA toxicity. Increased cell death and decrease in cell number was detected under both metabolic conditions. However, immunoblotting did not show any changes in the protein levels of the catalytic subunit A of mitochondrial DNA polymerase γ, the mitochondrial respiratory chain complexes I, II and IV, ATP synthase, E3 subunit dihydrolipoyl dehydrogenase of pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and glutathione peroxidase. Our results show that VPA inhibits mitochondrial respiration and leads to mitochondrial dysfunction, oxidative stress and increased cell death, thus suggesting an essential role of mitochondria in VPA-induced hepatotoxicity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Fluid Mechanical Forces and Endothelial Mitochondria: A Bioengineering Perspective.

PubMed

Scheitlin, Christopher G; Nair, Devi M; Crestanello, Juan A; Zweier, Jay L; Alevriadou, B Rita

2014-12-01

Endothelial cell dysfunction is the hallmark of every cardiovascular disease/condition, including atherosclerosis and ischemia/reperfusion injury. Fluid shear stress acting on the vascular endothelium is known to regulate cell homeostasis. Altered hemodynamics is thought to play a causative role in endothelial dysfunction. The dysfunction is associated with/preceded by mitochondrial oxidative stress. Studies by our group and others have shown that the form and/or function of the mitochondrial network are affected when endothelial cells are exposed to shear stress in the absence or presence of additional physicochemical stimuli. The present review will summarize the current knowledge on the interconnections among intracellular Ca 2+ - nitric oxide - mitochondrial reactive oxygen species, mitochondrial fusion/fission, autophagy/mitophagy, and cell apoptosis vs. survival. More specifically, it will list the evidence on potential regulation of the above intracellular species and processes by the fluid shear stress acting on the endothelium under either physiological flow conditions or during reperfusion (following a period of ischemia). Understanding how the local hemodynamics affects mitochondrial physiology and the cell redox state may lead to development of novel therapeutic strategies for prevention or treatment of the endothelial dysfunction and, hence, of cardiovascular disease.

Increased androgen levels in rats impair glucose-stimulated insulin secretion through disruption of pancreatic beta cell mitochondrial function.

PubMed

Wang, Hongdong; Wang, Xiaping; Zhu, Yunxia; Chen, Fang; Sun, Yujie; Han, Xiao

2015-11-01

Although insulin resistance is recognized to contribute to the reproductive and metabolic phenotypes of polycystic ovary syndrome (PCOS), pancreatic beta cell dysfunction plays an essential role in the progression from PCOS to the development of type 2 diabetes. However, the role of insulin secretory abnormalities in PCOS has received little attention. In addition, the precise changes in beta cells and the underlying mechanisms remain unclear. In this study, we therefore attempted to elucidate potential mechanisms involved in beta cell alterations in a rat model of PCOS. Glucose-induced insulin secretion was measured in islets isolated from DHT-treated and control rats. Oxygen consumption rate (OCR), ATP production, and mitochondrial copy number were assayed to evaluate mitochondrial function. Glucose-stimulated insulin secretion is significantly decreased in islets from DHT-treated rats. On the other hand, significant reductions are observed in the expression levels of several key genes involved in mitochondrial biogenesis and in mitochondrial OCR and ATP production in DHT-treated rat islets. Meanwhile, we found that androgens can directly impair beta cell function by inducing mitochondrial dysfunction in vitro in an androgen receptor dependent manner. For the first time, our study demonstrates that increased androgens in female rats can impair glucose-stimulated insulin secretion partly through disruption of pancreatic beta cell mitochondrial function. This work has significance for hyperandrogenic women with PCOS: excess activation of the androgen receptor by androgens may provoke beta cell dysfunction via mitochondrial dysfunction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Creatine protects against mitochondrial dysfunction associated with HIV-1 Tat-induced neuronal injury

PubMed Central

Stevens, Patrick R.; Gawryluk, Jeremy W.; Hui, Liang; Chen, Xuesong; Geiger, Jonathan D.

2015-01-01

HIV-1 infected individuals are living longer but experiencing a prevalence rate of over 50% for HIV-1 associated neurocognitive disorders (HAND) for which no effective treatment is available. Viral and cellular factors secreted by HIV-1 infected cells leads to neuronal injury and HIV-1 Tat continues to be implicated in the pathogenesis of HAND. Here we tested the hypothesis that creatine protected against HIV-1 Tat-induced neuronal injury by preventing mitochondrial bioenergetic crisis and/or redox catastrophe. Creatine blocked HIV-1 Tat1-72-induced increases in neuron cell death and synaptic area loss. Creatine protected against HIV-1 Tat-induced decreases in ATP. Creatine and creatine plus HIV-1 Tat increased cellular levels of creatine, and creatine plus HIV-1 Tat further decreased ratios of phosphocreatine to creatine observed with creatine or HIV-1 Tat treatments alone. Additionally, creatine protected against HIV-1 Tat-induced mitochondrial hypopolarization and HIV-1 Tat-induced mitochondrial permeability transition pore opening. Thus, creatine may be a useful adjunctive therapy against HAND. PMID:25613139

The Mitochondria in Diabetic Heart Failure: From Pathogenesis to Therapeutic Promise

PubMed Central

2015-01-01

Abstract Significance: Diabetes is an important risk factor for the development of heart failure (HF). Given the increasing prevalence of diabetes in the population, strategies are needed to reduce the burden of HF in these patients. Recent Advances: Diabetes is associated with several pathologic findings in the heart including dysregulated metabolism, lipid accumulation, oxidative stress, and inflammation. Emerging evidence suggests that mitochondrial dysfunction may be a central mediator of these pathologic responses. The development of therapeutic approaches targeting mitochondrial biology holds promise for the management of HF in diabetic patients. Critical Issues: Despite significant data implicating mitochondrial pathology in diabetic cardiomyopathy, the optimal pharmacologic approach to improve mitochondrial function remains undefined. Future Directions: Detailed mechanistic studies coupled with more robust clinical phenotyping will be necessary to develop novel approaches to improve cardiac function in diabetes. Moreover, understanding the interplay between diabetes and other cardiac stressors (hypertension, ischemia, and valvular disease) will be of the utmost importance for clinical translation of scientific discoveries made in this field. Antioxid. Redox Signal. 22, 1515–1526. PMID:25761843

Changes of TSPO-mediated mitophagy signaling pathway in learned helplessness mice.

PubMed

Li, Dongmei; Zheng, Ji; Wang, Mingyang; Feng, Lu; Ren, Zhili; Liu, Yanyong; Yang, Nan; Zuo, Pingping

2016-11-30

Low response rate was witnessed with the present monoaminergic based antidepressants, urging a need for new therapeutic target identification. Accumulated evidences strongly suggest that mitochondrial deficit is implicated in major depression and 18kDa translocator protein (TSPO) plays an important role in regulating mitochondrial function. However the changes of TSPO and TSPO mediated mitophagy pathway in the depressive brain is unclear. In present study, a well validated animal model of depression, learned helplessness (LH), was employed to investigate the relevant changes. Significant behavioral changes were observed in the LH mice. Results showed that TSPO and other mitophagy related proteins, such as VDAC1, Pink1 and Beclin1 were significantly decreased by LH challenge. Moreover, KIFC2, relevant to the mitochondrial transport and Snap25, relevant to neurotransmitter vesicle release, were also obviously down-regulated in the LH mice, which further rendered supportive evidence for the existing mitochondrial dysfunction in LH mice. Present results demonstrated that LH induced depressive symptoms and affected TSPO-mediated mitophagy pathway, indicating a potential target candidate for depression treatment. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Bovine and murine models highlight novel roles for SLC25A46 in mitochondrial dynamics and metabolism, with implications for human and animal health

PubMed Central

Vaiman, Anne; Beauvallet, Christian; Floriot, Sandrine; Rodriguez, Sabrina; Vilotte, Marthe; Boulanger, Laurent; Albaric, Olivier; Guillaume, François; Boukadiri, Abdelhak; Richard, Laurence; Bertaud, Maud; Timsit, Edouard; Guatteo, Raphaël; Jaffrézic, Florence; Calvel, Pierre; Helary, Louise; Mahla, Rachid; Esquerré, Diane; Péchoux, Christine; Liuu, Sophie; Boichard, Didier; Slama, Abdelhamid; Vilotte, Jean-Luc

2017-01-01

Neuropathies are neurodegenerative diseases affecting humans and other mammals. Many genetic causes have been identified so far, including mutations of genes encoding proteins involved in mitochondrial dynamics. Recently, the “Turning calves syndrome”, a novel sensorimotor polyneuropathy was described in the French Rouge-des-Prés cattle breed. In the present study, we determined that this hereditary disease resulted from a single nucleotide substitution in SLC25A46, a gene encoding a protein of the mitochondrial carrier family. This mutation caused an apparent damaging amino-acid substitution. To better understand the function of this protein, we knocked out the Slc25a46 gene in a mouse model. This alteration affected not only the nervous system but also altered general metabolism, resulting in premature mortality. Based on optic microscopy examination, electron microscopy and on biochemical, metabolic and proteomic analyses, we showed that the Slc25a46 disruption caused a fusion/fission imbalance and an abnormal mitochondrial architecture that disturbed mitochondrial metabolism. These data extended the range of phenotypes associated with Slc25a46 dysfunction. Moreover, this Slc25a46 knock-out mouse model should be useful to further elucidate the role of SLC25A46 in mitochondrial dynamics. PMID:28376083

Naked mole-rats maintain healthy skeletal muscle and Complex IV mitochondrial enzyme function into old age

PubMed Central

Stoll, Elizabeth A; Karapavlovic, Nevena; Rosa, Hannah; Woodmass, Michael; Rygiel, Karolina; White, Kathryn; Turnbull, Douglass M; Faulkes, Chris G

2016-01-01

The naked mole-rat (NMR) Heterocephalus glaber is an exceptionally long-lived rodent, living up to 32 years in captivity. This extended lifespan is accompanied by a phenotype of negligible senescence, a phenomenon of very slow changes in the expected physiological characteristics with age. One of the many consequences of normal aging in mammals is the devastating and progressive loss of skeletal muscle, termed sarcopenia, caused in part by respiratory enzyme dysfunction within the mitochondria of skeletal muscle fibers. Here we report that NMRs avoid sarcopenia for decades. Muscle fiber integrity and mitochondrial ultrastructure are largely maintained in aged animals. While mitochondrial Complex IV expression and activity remains stable, Complex I expression is significantly decreased. We show that aged naked mole-rat skeletal muscle tissue contains some mitochondrial DNA rearrangements, although the common mitochondrial DNA deletions associated with aging in human and other rodent skeletal muscles are not present. Interestingly, NMR skeletal muscle fibers demonstrate a significant increase in mitochondrial DNA copy number. These results have intriguing implications for the role of mitochondria in aging, suggesting Complex IV, but not Complex I, function is maintained in the long-lived naked mole rat, where sarcopenia is avoided and healthy muscle function is maintained for decades. PMID:27997359

Mpv17 in mitochondria protects podocytes against mitochondrial dysfunction and apoptosis in vivo and in vitro.

PubMed

Casalena, Gabriela; Krick, Stefanie; Daehn, Ilse; Yu, Liping; Ju, Wenjun; Shi, Shaolin; Tsai, Su-yi; D'Agati, Vivette; Lindenmeyer, Maja; Cohen, Clemens D; Schlondorff, Detlef; Bottinger, Erwin P

2014-06-01

Mitochondrial dysfunction is increasingly recognized as contributing to glomerular diseases, including those secondary to mitochondrial DNA (mtDNA) mutations and deletions. Mitochondria maintain cellular redox and energy homeostasis and are a major source of intracellular reactive oxygen species (ROS) production. Mitochondrial ROS accumulation may contribute to stress-induced mitochondrial dysfunction and apoptosis and thereby to glomerulosclerosis. In mice, deletion of the gene encoding Mpv17 is associated with glomerulosclerosis, but the underlying mechanism remains poorly defined. Here we report that Mpv17 localizes to mitochondria of podocytes and its expression is reduced in several glomerular injury models and in human focal segmental glomerulosclerosis (FSGS) but not in minimal change disease. Using models of mild or severe nephrotoxic serum nephritis (NTSN) in Mpv17(+/+) wild-type (WT) and Mpv17(-/-) knockout mice, we found that Mpv17 deficiency resulted in increased proteinuria (mild NTSN) and renal insufficiency (severe NTSN) compared with WT. These lesions were associated with increased mitochondrial ROS generation and mitochondrial injury such as oxidative DNA damage. In vitro, podocytes with loss of Mpv17 function were characterized by increased susceptibility to apoptosis and ROS injury including decreased mitochondrial function, loss of mtDNA content, and change in mitochondrial configuration. In summary, the inner mitochondrial membrane protein Mpv17 in podocytes is essential for the maintenance of mitochondrial homeostasis and protects podocytes against oxidative stress-induced injury both in vitro and in vivo. Copyright © 2014 the American Physiological Society.

Mitochondria and heart failure.

PubMed

Murray, Andrew J; Edwards, Lindsay M; Clarke, Kieran

2007-11-01

Energetic abnormalities in cardiac and skeletal muscle occur in heart failure and correlate with clinical symptoms and mortality. It is likely that the cellular mechanism leading to energetic failure involves mitochondrial dysfunction. Therefore, it is crucial to elucidate the causes of mitochondrial myopathy, in order to improve cardiac and skeletal muscle function, and hence quality of life, in heart failure patients. Recent studies identified several potential stresses that lead to mitochondrial dysfunction in heart failure. Chronically elevated plasma free fatty acid levels in heart failure are associated with decreased metabolic efficiency and cellular insulin resistance. Tissue hypoxia, resulting from low cardiac output and endothelial impairment, can lead to oxidative stress and mitochondrial DNA damage, which in turn causes dysfunction and loss of mitochondrial mass. Therapies aimed at protecting mitochondrial function have shown promise in patients and animal models with heart failure. Despite current therapies, which provide substantial benefit to patients, heart failure remains a relentlessly progressive disease, and new approaches to treatment are necessary. Novel pharmacological agents are needed that optimize substrate metabolism and maintain mitochondrial integrity, improve oxidative capacity in heart and skeletal muscle, and alleviate many of the clinical symptoms associated with heart failure.

In Vivo Determination of Mitochondrial Function Using Luciferase-Expressing Caenorhabditis elegans: Contribution of Oxidative Phosphorylation, Glycolysis, and Fatty Acid Oxidation to Toxicant-Induced Dysfunction.

PubMed

Luz, Anthony L; Lagido, Cristina; Hirschey, Matthew D; Meyer, Joel N

2016-08-01

Mitochondria are a target of many drugs and environmental toxicants; however, how toxicant-induced mitochondrial dysfunction contributes to the progression of human disease remains poorly understood. To address this issue, in vivo assays capable of rapidly assessing mitochondrial function need to be developed. Here, using the model organism Caenorhabditis elegans, we describe how to rapidly assess the in vivo role of the electron transport chain, glycolysis, or fatty acid oxidation in energy metabolism following toxicant exposure, using a luciferase-expressing ATP reporter strain. Alterations in mitochondrial function subsequent to toxicant exposure are detected by depleting steady-state ATP levels with inhibitors of the mitochondrial electron transport chain, glycolysis, or fatty acid oxidation. Differential changes in ATP following short-term inhibitor exposure indicate toxicant-induced alterations at the site of inhibition. Because a microplate reader is the only major piece of equipment required, this is a highly accessible method for studying toxicant-induced mitochondrial dysfunction in vivo. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

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

PubMed

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

2017-02-01

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

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

Treating SCA1 Mice with Water-Soluble Compounds to Non-Specifically Boost Mitochondrial Function.

PubMed

Ferro, Austin; Carbone, Emily; Marzouk, Evan; Siegel, Asher; Nguyen, Donna; Polley, Kailen; Hartman, Jessilyn; Frederick, Kimberley; Ives, Stephen; Lagalwar, Sarita

2017-01-22

Mitochondrial dysfunction plays a significant role in the aging process and in neurodegenerative diseases including several hereditary spinocerebellar ataxias and other movement disorders marked by progressive degeneration of the cerebellum. The goal of this protocol is to assess mitochondrial dysfunction in Spinocerebellar ataxia type 1 (SCA1) and assess the efficacy of pharmacological targeting of metabolic respiration via the water-soluble compound succinic acid to slow disease progression. This approach is applicable to other cerebellar diseases and can be adapted to a host of water-soluble therapies. Ex vivo analysis of mitochondrial respiration is used to detect and quantify disease-related changes in mitochondrial function. With genetic evidence (unpublished data) and proteomic evidence of mitochondrial dysfunction in the SCA1 mouse model, we evaluate the efficacy of treatment with the water-soluble metabolic booster succinic acid by dissolving this compound directly into the home cage drinking water. The ability of the drug to pass the blood brain barrier can be deduced using high performance liquid chromatography (HPLC). The efficacy of these compounds can then be tested using multiple behavioral paradigms including the accelerating rotarod, balance beam test and footprint analysis. Cytoarchitectural integrity of the cerebellum can be assessed using immunofluorescence assays that detect Purkinje cell nuclei and Purkinje cell dendrites and soma. These methods are robust techniques for determining mitochondrial dysfunction and the efficacy of treatment with water-soluble compounds in cerebellar neurodegenerative disease.

Lutein protects dopaminergic neurons against MPTP-induced apoptotic death and motor dysfunction by ameliorating mitochondrial disruption and oxidative stress.

PubMed

Nataraj, Jagatheesan; Manivasagam, Thamilarasan; Thenmozhi, Arokiasamy Justin; Essa, Musthafa Mohammed

2016-07-01

Mitochondrial dysfunction and oxidative stress-mediated apoptosis plays an important role in various neurodegenerative diseases including Huntington's disease, Parkinson's disease (PD) and Alzheimer's disease (AD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the most widely used neurotoxin mimics the symptoms of PD by inhibiting mitochondrial complex I that stimulates excessive intracellular reactive oxygen species (ROS) and finally leads to mitochondrial-dependent apoptosis. Lutein, a carotenoid of xanthophyll family, is found abundantly in leafy green vegetables such as spinach, kale and in egg yolk, animal fat and human eye retinal macula. Increasing evidence indicates that lutein has offers benefits against neuronal damages during diabetic retinopathy, ischemia and AD by virtue of its mitochondrial protective, antioxidant and anti-apoptotic properties. Male C57BL/6 mice (23-26 g) were randomized and grouped in to Control, MPTP, and Lutein treated groups. Lutein significantly reversed the loss of nigral dopaminergic neurons by increasing the striatal dopamine level in mice. Moreover, lutein-ameliorated MPTP induced mitochondrial dysfunction, oxidative stress and motor abnormalities. In addition, lutein repressed the MPTP-induced neuronal damage/apoptosis by inhibiting the activation of pro-apoptotic markers (Bax, caspases-3, 8 and 9) and enhancing anti-apoptotic marker (Bcl-2) expressions. Our current results revealed that lutein possessed protection on dopaminergic neurons by enhancing antioxidant defense and diminishing mitochondrial dysfunction and apoptotic death, suggesting the potential benefits of lutein for PD treatment.

MitoQ administration prevents endotoxin-induced cardiac dysfunction

PubMed Central

Murphy, M. P.; Callahan, L. A.

2009-01-01

Sepsis elicits severe alterations in cardiac function, impairing cardiac mitochondrial and pressure-generating capacity. Currently, there are no therapies to prevent sepsis-induced cardiac dysfunction. We tested the hypothesis that administration of a mitochondrially targeted antioxidant, 10-(6′-ubiquinonyl)-decyltriphenylphosphonium (MitoQ), would prevent endotoxin-induced reductions in cardiac mitochondrial and contractile function. Studies were performed on adult rodents (n = 52) given either saline, endotoxin (8 mg·kg−1·day−1), saline + MitoQ (500 μM), or both endotoxin and MitoQ. At 48 h animals were killed and hearts were removed for determination of either cardiac mitochondrial function (using polarography) or cardiac pressure generation (using the Langendorf technique). We found that endotoxin induced reductions in mitochondrial state 3 respiration rates, the respiratory control ratio, and ATP generation. Moreover, MitoQ administration prevented each of these endotoxin-induced abnormalities, P < 0.001. We also found that endotoxin produced reductions in cardiac pressure-generating capacity, reducing the systolic pressure-diastolic relationship. MitoQ also prevented endotoxin-induced reductions in cardiac pressure generation, P < 0.01. One potential link between mitochondrial and contractile dysfunction is caspase activation; we found that endotoxin increased cardiac levels of active caspases 9 and 3 (P < 0.001), while MitoQ prevented this increase (P < 0.01). These data demonstrate that MitoQ is a potent inhibitor of endotoxin-induced mitochondrial and cardiac abnormalities. We speculate that this agent may prove a novel therapy for sepsis-induced cardiac dysfunction. PMID:19657095

MitoQ administration prevents endotoxin-induced cardiac dysfunction.

PubMed

Supinski, G S; Murphy, M P; Callahan, L A

2009-10-01

Sepsis elicits severe alterations in cardiac function, impairing cardiac mitochondrial and pressure-generating capacity. Currently, there are no therapies to prevent sepsis-induced cardiac dysfunction. We tested the hypothesis that administration of a mitochondrially targeted antioxidant, 10-(6'-ubiquinonyl)-decyltriphenylphosphonium (MitoQ), would prevent endotoxin-induced reductions in cardiac mitochondrial and contractile function. Studies were performed on adult rodents (n = 52) given either saline, endotoxin (8 mg x kg(-1) x day(-1)), saline + MitoQ (500 microM), or both endotoxin and MitoQ. At 48 h animals were killed and hearts were removed for determination of either cardiac mitochondrial function (using polarography) or cardiac pressure generation (using the Langendorf technique). We found that endotoxin induced reductions in mitochondrial state 3 respiration rates, the respiratory control ratio, and ATP generation. Moreover, MitoQ administration prevented each of these endotoxin-induced abnormalities, P < 0.001. We also found that endotoxin produced reductions in cardiac pressure-generating capacity, reducing the systolic pressure-diastolic relationship. MitoQ also prevented endotoxin-induced reductions in cardiac pressure generation, P < 0.01. One potential link between mitochondrial and contractile dysfunction is caspase activation; we found that endotoxin increased cardiac levels of active caspases 9 and 3 (P < 0.001), while MitoQ prevented this increase (P < 0.01). These data demonstrate that MitoQ is a potent inhibitor of endotoxin-induced mitochondrial and cardiac abnormalities. We speculate that this agent may prove a novel therapy for sepsis-induced cardiac dysfunction.

Prevention of Trauma/Hemorrhagic Shock-Induced Mortality, Apoptosis, Inflammation and Mitochondrial Dysfunction Using IL-6 as a Resuscitation Adjuvant

DTIC Science & Technology

2011-12-01

infiltrating PMNs is not merely limited to organs that have been directly injured from trauma. Ischemia - reperfusion injury (which occurs after... injury by facilitating inflammatory cell adhesion in an animal model of myocardial ischemia - reperfusion [61,62]. Fabp2 and Fabp5 have been implicated in...Bauer A, Tweardy DJ (1998) Activation of STAT proteins following ischemia reperfusion injury demonstrates a distinct IL- 6 and G-CSF mediated profile

Mitochondrial Fusion/Fission, Transport and Autophagy in Parkinson's Disease: When Mitochondria Get Nasty

PubMed Central

Arduíno, Daniela M.; Esteves, A. Raquel; Cardoso, Sandra M.

2011-01-01

Understanding the molecular basis of Parkinson's disease (PD) has proven to be a major challenge in the field of neurodegenerative diseases. Although several hypotheses have been proposed to explain the molecular mechanisms underlying the pathogenesis of PD, a growing body of evidence has highlighted the role of mitochondrial dysfunction and the disruption of the mechanisms of mitochondrial dynamics in PD and other parkinsonian disorders. In this paper, we comment on the recent advances in how changes in the mitochondrial function and mitochondrial dynamics (fusion/fission, transport, and clearance) contribute to neurodegeneration, specifically focusing on PD. We also evaluate the current controversies in those issues and discuss the role of fusion/fission dynamics in the mitochondrial lifecycle and maintenance. We propose that cellular demise and neurodegeneration in PD are due to the interplay between mitochondrial dysfunction, mitochondrial trafficking disruption, and impaired autophagic clearance. PMID:21403911

Mitochondrial fusion/fission, transport and autophagy in Parkinson's disease: when mitochondria get nasty.

PubMed

Arduíno, Daniela M; Esteves, A Raquel; Cardoso, Sandra M

2011-02-20

Understanding the molecular basis of Parkinson's disease (PD) has proven to be a major challenge in the field of neurodegenerative diseases. Although several hypotheses have been proposed to explain the molecular mechanisms underlying the pathogenesis of PD, a growing body of evidence has highlighted the role of mitochondrial dysfunction and the disruption of the mechanisms of mitochondrial dynamics in PD and other parkinsonian disorders. In this paper, we comment on the recent advances in how changes in the mitochondrial function and mitochondrial dynamics (fusion/fission, transport, and clearance) contribute to neurodegeneration, specifically focusing on PD. We also evaluate the current controversies in those issues and discuss the role of fusion/fission dynamics in the mitochondrial lifecycle and maintenance. We propose that cellular demise and neurodegeneration in PD are due to the interplay between mitochondrial dysfunction, mitochondrial trafficking disruption, and impaired autophagic clearance.

Dorsal Anterior Cingulate Lactate and Glutathione Levels in Euthymic Bipolar I Disorder: 1H-MRS Study.

PubMed

Soeiro-de-Souza, Márcio Gerhardt; Pastorello, Bruno F; Leite, Cláudia da Costa; Henning, Anke; Moreno, Ricardo A; Garcia Otaduy, Maria Concepción

2016-08-01

Oxidative stress and mitochondrial dysfunction are 2 closely integrated processes implicated in the physiopathology of bipolar disorder. Advanced proton magnetic resonance spectroscopy techniques enable the measurement of levels of lactate, the main marker of mitochondrial dysfunction, and glutathione, the predominant brain antioxidant. The objective of this study was to measure brain lactate and glutathione levels in bipolar disorder and healthy controls. Eighty-eight individuals (50 bipolar disorder and 38 healthy controls) underwent 3T proton magnetic resonance spectroscopy in the dorsal anterior cingulate cortex (2x2x4.5cm(3)) using a 2-D JPRESS sequence. Lactate and glutathione were quantified using the ProFit software program. Bipolar disorder patients had higher dorsal anterior cingulate cortex lactate levels compared with controls. Glutathione levels did not differ between euthymic bipolar disorder and controls. There was a positive correlation between lactate and glutathione levels specific to bipolar disorder. No influence of medications on metabolites was observed. This is the most extensive magnetic resonance spectroscopy study of lactate and glutathione in bipolar disorder to date, and results indicated that euthymic bipolar disorder patients had higher levels of lactate, which might be an indication of altered mitochondrial function. Moreover, lactate levels correlated with glutathione levels, indicating a compensatory mechanism regardless of bipolar disorder diagnosis. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Dorsal Anterior Cingulate Lactate and Glutathione Levels in Euthymic Bipolar I Disorder: 1H-MRS Study

PubMed Central

Pastorello, Bruno F.; Leite, Cláudia da Costa; Henning, Anke; Moreno, Ricardo A.; Garcia Otaduy, Maria Concepción

2016-01-01

Objective: Oxidative stress and mitochondrial dysfunction are 2 closely integrated processes implicated in the physiopathology of bipolar disorder. Advanced proton magnetic resonance spectroscopy techniques enable the measurement of levels of lactate, the main marker of mitochondrial dysfunction, and glutathione, the predominant brain antioxidant. The objective of this study was to measure brain lactate and glutathione levels in bipolar disorder and healthy controls. Methods: Eighty-eight individuals (50 bipolar disorder and 38 healthy controls) underwent 3T proton magnetic resonance spectroscopy in the dorsal anterior cingulate cortex (2x2x4.5cm3) using a 2-D JPRESS sequence. Lactate and glutathione were quantified using the ProFit software program. Results: Bipolar disorder patients had higher dorsal anterior cingulate cortex lactate levels compared with controls. Glutathione levels did not differ between euthymic bipolar disorder and controls. There was a positive correlation between lactate and glutathione levels specific to bipolar disorder. No influence of medications on metabolites was observed. Conclusion: This is the most extensive magnetic resonance spectroscopy study of lactate and glutathione in bipolar disorder to date, and results indicated that euthymic bipolar disorder patients had higher levels of lactate, which might be an indication of altered mitochondrial function. Moreover, lactate levels correlated with glutathione levels, indicating a compensatory mechanism regardless of bipolar disorder diagnosis. PMID:27207914

Interaction theory of mammalian mitochondria.

PubMed

Nakada, K; Inoue, K; Hayashi, J

2001-11-09

We generated mice with deletion mutant mtDNA by its introduction from somatic cells into mouse zygotes. Expressions of disease phenotypes are limited to tissues expressing mitochondrial dysfunction. Considering that all these mice share the same nuclear background, these observations suggest that accumulation of the mutant mtDNA and resultant expressions of mitochondrial dysfunction are responsible for expression of disease phenotypes. On the other hand, mitochondrial dysfunction and expression of clinical abnormalities were not observed until the mutant mtDNA accumulated predominantly. This protection is due to the presence of extensive and continuous interaction between exogenous mitochondria from cybrids and recipient mitochondria from embryos. Thus, we would like to propose a new hypothesis on mitochondrial biogenesis, interaction theory of mitochondria: mammalian mitochondria exchange genetic contents, and thus lost the individuality and function as a single dynamic cellular unit. Copyright 2001 Academic Press.

Transient Receptor Potential Vanilloid 1 Expression Mediates Capsaicin-Induced Cell Death.

PubMed

Ramírez-Barrantes, Ricardo; Córdova, Claudio; Gatica, Sebastian; Rodriguez, Belén; Lozano, Carlo; Marchant, Ivanny; Echeverria, Cesar; Simon, Felipe; Olivero, Pablo

2018-01-01

The transient receptor potential (TRP) ion channel family consists of a broad variety of non-selective cation channels that integrate environmental physicochemical signals for dynamic homeostatic control. Involved in a variety of cellular physiological processes, TRP channels are fundamental to the control of the cell life cycle. TRP channels from the vanilloid (TRPV) family have been directly implicated in cell death. TRPV1 is activated by pain-inducing stimuli, including inflammatory endovanilloids and pungent exovanilloids, such as capsaicin (CAP). TRPV1 activation by high doses of CAP (>10 μM) leads to necrosis, but also exhibits apoptotic characteristics. However, CAP dose-response studies are lacking in order to determine whether CAP-induced cell death occurs preferentially via necrosis or apoptosis. In addition, it is not known whether cytosolic Ca 2+ and mitochondrial dysfunction participates in CAP-induced TRPV1-mediated cell death. By using TRPV1-transfected HeLa cells, we investigated the underlying mechanisms involved in CAP-induced TRPV1-mediated cell death, the dependence of CAP dose, and the participation of mitochondrial dysfunction and cytosolic Ca 2+ increase. Together, our results contribute to elucidate the pathophysiological steps that follow after TRPV1 stimulation with CAP. Low concentrations of CAP (1 μM) induce cell death by a mechanism involving a TRPV1-mediated rapid and transient intracellular Ca 2+ increase that stimulates plasma membrane depolarization, thereby compromising plasma membrane integrity and ultimately leading to cell death. Meanwhile, higher doses of CAP induce cell death via a TRPV1-independent mechanism, involving a slow and persistent intracellular Ca 2+ increase that induces mitochondrial dysfunction, plasma membrane depolarization, plasma membrane loss of integrity, and ultimately, cell death.

Curcuminoid EF24 enhances the anti-tumour activity of Akt inhibitor MK-2206 through ROS-mediated endoplasmic reticulum stress and mitochondrial dysfunction in gastric cancer.

PubMed

Chen, Xi; Dai, Xuanxuan; Zou, Peng; Chen, Weiqian; Rajamanickam, Vinothkumar; Feng, Chen; Zhuge, Weishan; Qiu, Chenyu; Ye, Qingqing; Zhang, Xiaohua; Liang, Guang

2017-05-01

Gastric cancer is one of the leading causes of morbidity and mortality worldwide. Akt is an anti-apoptotic kinase that plays a dynamic role in cell survival and is implicated in the pathogenesis of gastric cancer. MK-2206, the first allosteric inhibitor of Akt, is in clinical trials for a number of cancers. Although preclinical studies showed promise, clinical trials reported it had no effect when given alone at tolerated doses. The aim of our study was to delineate the effects of MK-2206 on gastric cancer cells and explore the ability of combination treatments to enhance the anti-tumour activity of MK-2206. SGC-7901, BGC-823 cells and immunodeficient mice were chosen as a model to study the treatment effects. Changes in cell viability, apoptosis and ROS, endoplasmic reticulum stress and mitochondrial dysfunction in the cells were analysed by MTT assays, ROS imaging and FACSCalibur, electron microscopy, JC-1 staining and western blotting. MK-2206 induced apoptotic cell death through the generation of ROS. We utilized ROS production to target gastric cancer cells by combining MK-2206 and an ROS inducer EF24. Our in vitro and in vivo xenograft studies showed that combined treatment with MK-2206 and EF24 synergistically induced apoptosis in gastric cancer cells and caused cell cycle arrest. These activities were mediated through ROS generation and the induction of endoplasmic reticulum stress and mitochondrial dysfunction. Targeting ROS generation by using a combination of an Akt inhibitor and EF24 could have potential as a therapy for gastric cancer. © 2017 The British Pharmacological Society.

Mitochondrial Dysfunctions in Bipolar Disorder: Effect of the Disease and Pharmacotherapy.

PubMed

Cikankova, Tereza; Sigitova, Ekaterina; Zverova, Martina; Fisar, Zdenek; Raboch, Jiri; Hroudova, Jana

2017-01-01

Exact pathophysiological mechanisms of bipolar disorder have not been sufficiently clarified. We review the evidence of mitochondrial dysfunctions on the relation between both disease and pharmacotherapy. Mitochondria produce the most of energy-rich molecules of adenosine triphosphate (ATP), apart from energy production they are involved in other functions: regulation of free radicals, antioxidant defenses, lipid peroxidation, calcium metabolism and participate in the intrinsic pathway of apoptosis. According to increasing evidence dysfunctions of mitochondria are associated with affective disorders, a hypothesis of impaired mitochondrial functions has been proposed in bipolar disorder pathogenesis. Mitochondrial DNA mutations and/or polymorphisms, impaired phospholipid metabolism and glycolytic shift, decrease in ATP production, increased oxidative stress and changes of intracellular calcium are concerned in mood disorders and effects of mood stabilizers. Recent studies have also provided data about the positive effects of chronic treatment by mood stabilizers on mitochondrial functions. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Chronic enrichment of hepatic endoplasmic reticulum-mitochondria contact leads to mitochondrial dysfunction in obesity.

PubMed

Arruda, Ana Paula; Pers, Benedicte M; Parlakgül, Güneş; Güney, Ekin; Inouye, Karen; Hotamisligil, Gökhan S

2014-12-01

Proper function of the endoplasmic reticulum (ER) and mitochondria is crucial for cellular homeostasis, and dysfunction at either site has been linked to pathophysiological states, including metabolic diseases. Although the ER and mitochondria play distinct cellular roles, these organelles also form physical interactions with each other at sites defined as mitochondria-associated ER membranes (MAMs), which are essential for calcium, lipid and metabolite exchange. Here we show that in the liver, obesity leads to a marked reorganization of MAMs resulting in mitochondrial calcium overload, compromised mitochondrial oxidative capacity and augmented oxidative stress. Experimental induction of ER-mitochondria interactions results in oxidative stress and impaired metabolic homeostasis, whereas downregulation of PACS-2 or IP3R1, proteins important for ER-mitochondria tethering or calcium transport, respectively, improves mitochondrial oxidative capacity and glucose metabolism in obese animals. These findings establish excessive ER-mitochondrial coupling as an essential component of organelle dysfunction in obesity that may contribute to the development of metabolic pathologies such as insulin resistance and diabetes.

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

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

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

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

Melatonin prevents abnormal mitochondrial dynamics resulting from the neurotoxicity of cadmium by blocking calcium-dependent translocation of Drp1 to the mitochondria.

PubMed

Xu, Shangcheng; Pi, Huifeng; Zhang, Lei; Zhang, Nixian; Li, YuMing; Zhang, Huiliang; Tang, Ju; Li, Huijuan; Feng, Min; Deng, Ping; Guo, Pan; Tian, Li; Xie, Jia; He, Mindi; Lu, Yonghui; Zhong, Min; Zhang, Yanwen; Wang, Wang; Reiter, Russel J; Yu, Zhengping; Zhou, Zhou

2016-04-01

Cadmium (Cd) is a persistent environmental toxin and occupational pollutant that is considered to be a potential risk factor in the development of neurodegenerative diseases. Abnormal mitochondrial dynamics are increasingly implicated in mitochondrial damage in various neurological pathologies. The aim of this study was to investigate whether the disturbance of mitochondrial dynamics contributed to Cd-induced neurotoxicity and whether melatonin has any neuroprotective properties. After cortical neurons were exposed to 10 μM cadmium chloride (CdCl2 ) for various periods (0, 3, 6, 12, and 24 hr), the morphology of their mitochondria significantly changed from the normal tubular networks into punctuated structures within 3 hr. Following this pronounced mitochondrial fragmentation, Cd treatment led to signs of mitochondrial dysfunction, including excess reactive oxygen species (ROS) production, decreased ATP content, and mitochondrial membrane potential (▵Ψm) loss. However, 1 mM melatonin pretreatment efficiently attenuated the Cd-induced mitochondrial fragmentation, which improved the turnover of mitochondrial function. In the brain tissues of rats that were intraperitoneally given 1 mg/kg CdCl2 for 7 days, melatonin also ameliorated excessive mitochondrial fragmentation and mitochondrial damage in vivo. Melatonin's protective effects were attributed to its roles in preventing cytosolic calcium ([Ca(2+) ]i ) overload, which blocked the recruitment of Drp1 from the cytoplasm to the mitochondria. Taken together, our results are the first to demonstrate that abnormal mitochondrial dynamics is involved in cadmium-induced neurotoxicity. Melatonin has significant pharmacological potential in protecting against the neurotoxicity of Cd by blocking the disbalance of mitochondrial fusion and fission. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Mitochondrial Dynamics in Diabetic Cardiomyopathy

PubMed Central

Galloway, Chad A.

2015-01-01

Abstract Significance: Cardiac function is energetically demanding, reliant on efficient well-coupled mitochondria to generate adenosine triphosphate and fulfill the cardiac demand. Predictably then, mitochondrial dysfunction is associated with cardiac pathologies, often related to metabolic disease, most commonly diabetes. Diabetic cardiomyopathy (DCM), characterized by decreased left ventricular function, arises independently of coronary artery disease and atherosclerosis. Dysregulation of Ca2+ handling, metabolic changes, and oxidative stress are observed in DCM, abnormalities reflected in alterations in mitochondrial energetics. Cardiac tissue from DCM patients also presents with altered mitochondrial morphology, suggesting a possible role of mitochondrial dynamics in its pathological progression. Recent Advances: Abnormal mitochondrial morphology is associated with pathologies across diverse tissues, suggesting that this highly regulated process is essential for proper cell maintenance and physiological homeostasis. Highly structured cardiac myofibers were hypothesized to limit alterations in mitochondrial morphology; however, recent work has identified morphological changes in cardiac tissue, specifically in DCM. Critical Issues: Mitochondrial dysfunction has been reported independently from observations of altered mitochondrial morphology in DCM. The temporal relationship and causative nature between functional and morphological changes of mitochondria in the establishment/progression of DCM is unclear. Future Directions: Altered mitochondrial energetics and morphology are not only causal for but also consequential to reactive oxygen species production, hence exacerbating oxidative damage through reciprocal amplification, which is integral to the progression of DCM. Therefore, targeting mitochondria for DCM will require better mechanistic characterization of morphological distortion and bioenergetic dysfunction. Antioxid. Redox Signal. 22, 1545–1562. PMID:25738230

Cardiac Dysfunction and Oxidative Stress in the Metabolic Syndrome: an Update on Antioxidant Therapies

PubMed Central

Ilkun, Olesya; Boudina, Sihem

2013-01-01

The metabolic syndrome (MetS) is a cluster of risk factors including obesity, insulin resistance, dyslipidemia, elevated blood pressure and glucose intolerance. The MetS increases the risk for cardiovascular disease (CVD) and type 2 diabetes. Each component of the MetS causes cardiac dysfunction and their combination carries additional risk. The mechanisms underlying cardiac dysfunction in the MetS are complex and might include lipid accumulation, increased fibrosis and stiffness, altered calcium homeostasis, abnormal autophagy, altered substrate utilization, mitochondrial dysfunction and increased oxidative stress. Mitochondrial and extra-mitochondrial sources of reactive oxygen species (ROS) and reduced antioxidant defense mechanisms characterize the myocardium of humans and animals with the MetS. The mechanisms for increased cardiac oxidative stress in the MetS are not fully understood but include increased fatty acid oxidation, mitochondrial dysfunction and enhanced NADPH oxidase activity. Therapies aimed to reduce oxidative stress and enhance antioxidant defense have been employed to reduce cardiac dysfunction in the MetS in animals. In contrast, large scale clinical trials using antioxidants therapies for the treatment of CVD have been disappointing because of the lack of efficacy and undesired side effects. The focus of this review is to summarize the current knowledge about the mechanisms underlying cardiac dysfunction in the MetS with a special interest in the role of oxidative stress. Finally, we will update the reader on the results obtained with natural antioxidant and mitochondria-targeted antioxidant therapies for the treatment of CVD in the MetS. PMID:23323621

Inhibition of Drp1 attenuates mitochondrial damage and myocardial injury in Coxsackievirus B3 induced myocarditis

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

Lin, Lin; Zhang, Ming; Yan, Rui

Viral myocarditis (VMC) is closely related to apoptosis, oxidative stress, innate immunity, and energy metabolism, which are all linked to mitochondrial dysfunction. A close nexus between mitochondrial dynamics and cardiovascular disease with mitochondrial dysfunction has been deeply researched, but there is still no relevant report in viral myocarditis. In this study, we aimed to explore the role of Dynamin-related protein 1 (Drp1)-linked mitochondrial fission in VMC. Mice were inoculated with the Coxsackievirus B3 (CVB3) and treated with mdivi1 (a Drp1 inhibitor). Protein expression of Drp1 was increased in mitochondria while decreased in cytoplasm and accompanied by excessive mitochondrial fission inmore » VMC mice. In addition, midivi1 treatment attenuate inflammatory cells infiltration in myocardium of the mice, serum Cardiac troponin I (CTnI) and Creatine kinase-MB (CK-MB) level. Mdivi1 also could improved the survival rate of mice and mitochondrial dysfunction reflected as the up-regulated mitochondrial marker enzymatic activities of succinate dehydrogenase (SDH), cytochrome c oxidase (COX) and mitochondrial membrane potential (MMP). At the same time, mdivi1 rescued the body weight loss, myocardial injury and apoptosis of cardiomyocyte. Furthermore, decease in LVEDs and increase in EF and FS were detected by echocardiogram, which indicated the improved myocardial function. Thus, Drp1-linked excessive mitochondrial fission contributed to VMC and midivi1 may be a potential therapeutic approach. - Highlights: • The expression of Drp1 is significantly increased in mitochondria while decreased in cytoplasm in VMC mice. • Drp1-linked excessive mitochondrial fission is involved in VMC. • Midivi1 treatment mitigate the mitochondrial damage, inflammation, apoptosis in VMC mice. • The disturbance of mitochondrial dynamics may be a new therapeutic target for VMC.« less

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

PubMed

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

2012-01-01

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

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

The single IGF-1 partial deficiency is responsible for mitochondrial dysfunction and is restored by IGF-1 replacement therapy.

PubMed

Olleros Santos-Ruiz, M; Sádaba, M C; Martín-Estal, I; Muñoz, U; Sebal Neira, C; Castilla-Cortázar, I

2017-08-01

We previously described in cirrhosis and aging, both conditions of IGF-1 deficiency, a clear hepatic mitochondrial dysfunction with increased oxidative damage. In both conditions, the hepatic mitochondrial function was improved with low doses of IGF-1. The aim of this work was to explore if the only mere IGF-1 partial deficiency, without any exogenous insult, is responsible for hepatic mitochondrial dysfunction. Heterozygous (igf1 +/- ) mice were divided into two groups: untreated and treated mice with low doses of IGF-1. WT group was used as controls. Parameters of hepatic mitochondrial function were determined by flow cytometry, antioxidant enzyme activities were determined by spectrophotometry, and electron chain transport enzyme levels were determined by immunohistochemistry and immunofluorescence analyses. Liver expression of genes coding for proteins involved in mitochondrial protection and apoptosis was studied by microarray analysis and RT-qPCR. Hz mice showed a significant reduction in hepatic mitochondrial membrane potential (MMP) and ATPase activity, and an increase in intramitochondrial free radical production and proton leak rates, compared to controls. These parameters were normalized by IGF-1 replacement therapy. No significant differences were found between groups in oxygen consumption and antioxidant enzyme activities, except for catalase, whose activity was increased in both Hz groups. Relevant genes coding for proteins involved in mitochondrial protection and survival were altered in Hz group and were reverted to normal in Hz+IGF-1 group. The mere IGF-1 partial deficiency is per se associated with hepatic mitochondrial dysfunction sensitive to IGF-1 replacement therapy. Results in this work prove that IGF-1 is involved in hepatic mitochondrial protection, because it is able to reduce free radical production, oxidative damage and apoptosis. All these IGF-1 actions are mediated by the modulation of the expression of genes encoding citoprotective and antiapoptotic proteins. Copyright © 2017. Published by Elsevier Ltd.

Glutamate antagonism fails to reverse mitochondrial dysfunction in late phase of experimental neonatal asphyxia in rats.

PubMed

Reddy, Nagannathahalli Ranga; Krishnamurthy, Sairam; Chourasia, Tapan Kumar; Kumar, Ashok; Joy, Keerikkattil Paily

2011-04-01

Neonatal asphyxia is a primary contributor to neonatal mortality and neuro-developmental disorders. It progresses in two distinct phases, as initial primary process and latter as the secondary process. A dynamic relationship exists between excitotoxicity and mitochondrial dysfunction during the progression of asphyxic injury. Study of status of glutamate and mitochondrial function in tandem during primary and secondary processes may give new leads to the treatment of asphyxia. Neonatal asphyxia was induced in rat pups on the day of birth by subjecting them to two episodes (10min each) of anoxia, 24h apart by passing 100% N(2) into an enclosed chamber. The NMDA antagonist ketamine (20mg/kg/day) was administered either for 1 day or 7 days after anoxic exposure. Tissue glutamate and nitric oxide were estimated in the cerebral cortex, extra-cortex and cerebellum. The mitochondria from the above brain regions were used for the estimation of malondialdehyde, and activities of superoxide dismutase and succinate dehydrogenase. Mitochondrial membrane potential was evaluated by using Rhodamine dye. Anoxia during the primary process increased glutamate and nitric oxide levels; however the mitochondrial function was unaltered in terms of succinate dehydrogenase and membrane potential. Acute ketamine treatment reversed the increase in both glutamate and nitric oxide levels and partially attenuated mitochondrial function in terms of succinate dehydrogenase activity. The elevated glutamate and nitric oxide levels were maintained during the secondary process but however with concomitant loss of mitochondrial function. Repeated ketamine administration reversed glutamate levels only in the cerebral cortex, where as nitric oxide was decreased in all the brain regions. However, repeated ketamine administration was unable to reverse anoxia-induced mitochondrial dysfunction. The failure of glutamate antagonism in the treatment of asphyxia may be due to persistence of mitochondrial dysfunction. Therefore, additionally targeting mitochondrial function may prove to be therapeutically beneficial in the treatment of asphyxia. Copyright © 2011 Elsevier Ltd. All rights reserved.

The mixture of "ecstasy" and its metabolites impairs mitochondrial fusion/fission equilibrium and trafficking in hippocampal neurons, at in vivo relevant concentrations.

PubMed

Barbosa, Daniel José; Serrat, Romàn; Mirra, Serena; Quevedo, Martí; de Barreda, Elena Goméz; Àvila, Jesús; Ferreira, Luísa Maria; Branco, Paula Sério; Fernandes, Eduarda; Lourdes Bastos, Maria de; Capela, João Paulo; Soriano, Eduardo; Carvalho, Félix

2014-06-01

3,4-Methylenedioxymethamphetamine (MDMA; "ecstasy") is a potentially neurotoxic recreational drug of abuse. Though the mechanisms involved are still not completely understood, formation of reactive metabolites and mitochondrial dysfunction contribute to MDMA-related neurotoxicity. Neuronal mitochondrial trafficking, and their targeting to synapses, is essential for proper neuronal function and survival, rendering neurons particularly vulnerable to mitochondrial dysfunction. Indeed, MDMA-associated disruption of Ca(2+) homeostasis and ATP depletion have been described in neurons, thus suggesting possible MDMA interference on mitochondrial dynamics. In this study, we performed real-time functional experiments of mitochondrial trafficking to explore the role of in situ mitochondrial dysfunction in MDMA's neurotoxic actions. We show that the mixture of MDMA and six of its major in vivo metabolites, each compound at 10μM, impaired mitochondrial trafficking and increased the fragmentation of axonal mitochondria in cultured hippocampal neurons. Furthermore, the overexpression of mitofusin 2 (Mfn2) or dynamin-related protein 1 (Drp1) K38A constructs almost completely rescued the trafficking deficits caused by this mixture. Finally, in hippocampal neurons overexpressing a Mfn2 mutant, Mfn2 R94Q, with impaired fusion and transport properties, it was confirmed that a dysregulation of mitochondrial fission/fusion events greatly contributed to the reported trafficking phenotype. In conclusion, our study demonstrated, for the first time, that the mixture of MDMA and its metabolites, at concentrations relevant to the in vivo scenario, impaired mitochondrial trafficking and increased mitochondrial fragmentation in hippocampal neurons, thus providing a new insight in the context of "ecstasy"-induced neuronal injury.

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

PubMed Central

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

2016-01-01

The regulatory dynamics of mitochondria comprises well orchestrated distribution and mitochondrial turnover to maintain the mitochondrial circuitry and homeostasis inside the cells. Several pieces of evidence suggested impaired mitochondrial dynamics and its association with the pathogenesis of neurodegenerative disorders. We found that chronic exposure of synthetic xenoestrogen bisphenol A (BPA), a component of consumer plastic products, impaired autophagy-mediated mitochondrial turnover, leading to increased oxidative stress, mitochondrial fragmentation, and apoptosis in hippocampal neural stem cells (NSCs). It also inhibited hippocampal derived NSC proliferation and differentiation, as evident by the decreased number of BrdU- and β-III tubulin-positive cells. All these effects were reversed by the inhibition of oxidative stress using N-acetyl cysteine. BPA up-regulated the levels of Drp-1 (dynamin-related protein 1) and enhanced its mitochondrial translocation, with no effect on Fis-1, Mfn-1, Mfn-2, and Opa-1 in vitro and in the hippocampus. Moreover, transmission electron microscopy studies suggested increased mitochondrial fission and accumulation of fragmented mitochondria and decreased elongated mitochondria in the hippocampus of the rat brain. Impaired mitochondrial dynamics by BPA resulted in increased reactive oxygen species and malondialdehyde levels, disruption of mitochondrial membrane potential, and ATP decline. Pharmacological (Mdivi-1) and genetic (Drp-1siRNA) inhibition of Drp-1 reversed BPA-induced mitochondrial dysfunctions, fragmentation, and apoptosis. Interestingly, BPA-mediated inhibitory effects on NSC proliferation and neuronal differentiations were also mitigated by Drp-1 inhibition. On the other hand, Drp-1 inhibition blocked BPA-mediated Drp-1 translocation, leading to decreased apoptosis of NSC. Overall, our studies implicate Drp-1 as a potential therapeutic target against BPA-mediated impaired mitochondrial dynamics and neurodegeneration in the hippocampus. PMID:27252377

Pink1/Parkin-mediated mitophagy play a protective role in cisplatin induced renal tubular epithelial cells injury.

PubMed

Zhao, Chuanyan; Chen, Zhuyun; Xu, Xueqiang; An, Xiaofei; Duan, Suyan; Huang, Zhimin; Zhang, Chengning; Wu, Lin; Zhang, Bo; Zhang, Aihua; Xing, Changying; Yuan, Yanggang

2017-01-15

Cisplatin often causes acute kidney injury (AKI) in the treatment of a wide variety of malignancies. Mitochondrial dysfunction is one of the main reasons for cisplatin nephrotoxicity. Previous study showed that Pink1 and Parkin play central roles in regulating the mitophagy, which is a key protective mechanism by specifically eliminating dysfunctional or damaged mitochondria. However, the mechanisms that modulate mitophagy in cisplatin induced nephrotoxicity remain to be elucidated. The purpose of this study was to investigate the effects of Pink1/Parkin pathway in mitophagy, mitochondrial dysfunction and renal proximal tubular cells injury during cisplatin treatment. In cultured human renal proximal tubular cells, we found that knockdown of Pink1/Parkin induced the aggravation of mitochondrial function, leading to the increase of cell injury through inhibition of mitophagy. Additionally, the overexpression of Pink1/Parkin protected against cisplatin-induced mitochondrial dysfunction and cell injury by promoting mitophagy. Our results provide clear evidence that Pink1/Parkin-dependent mitophagy has identified potential targets for the treatment of cisplatin-induced AKI. Copyright © 2016 Elsevier Inc. All rights reserved.

Oxygen matters: tissue culture oxygen levels affect mitochondrial function and structure as well as responses to HIV viroproteins

PubMed Central

Tiede, L M; Cook, E A; Morsey, B; Fox, H S

2011-01-01

Mitochondrial dysfunction is implicated in a majority of neurodegenerative disorders and much study of neurodegenerative disease is done on cultured neurons. In traditional tissue culture, the oxygen level that cells experience is dramatically higher (21%) than in vivo conditions (1–11%). These differences can alter experimental results, especially, pertaining to mitochondria and oxidative metabolism. Our results show that primary neurons cultured at physiological oxygen levels found in the brain showed higher polarization, lower rates of ROS production, larger mitochondrial networks, greater cytoplasmic fractions of mitochondria and larger mitochondrial perimeters than those cultured at higher oxygen levels. Although neurons cultured in either physiological oxygen or atmospheric oxygen exhibit significant increases in mitochondrial reactive oxygen species (ROS) production when treated with the human immunodeficiency virus (HIV) virotoxin trans-activator of transcription, mitochondria of neurons cultured at physiological oxygen underwent depolarization with dramatically increased cell death, whereas those cultured at atmospheric oxygen became hyperpolarized with no increase in cell death. Studies with a second HIV virotoxin, negative regulation factor (Nef), revealed that Nef treatment also increased mitochondrial ROS production for both the oxygen conditions, but resulted in mitochondrial depolarization and increased death only in neurons cultured in physiological oxygen. These results indicate a role for oxidative metabolism in a mechanism of neurotoxicity during HIV infection and demonstrate the importance of choosing the correct, physiological, culture oxygen in mitochondrial studies performed in neurons. PMID:22190005

Poor embryo development in post-ovulatory in vivo-aged mouse oocytes is associated with mitochondrial dysfunction, but mitochondrial transfer from somatic cells is not sufficient for rejuvenation.

PubMed

Igarashi, Hideki; Takahashi, Toshifumi; Abe, Hiroyuki; Nakano, Hiroshi; Nakajima, Osamu; Nagase, Satoru

2016-10-01

Does in vivo aging of mouse oocytes affect mitochondrial function? Mitochondrial function was impaired in post-ovulatory in vivo-aged mouse oocytes and microinjection of somatic cell mitochondria did not rescue poor fertilization and embryonic development rates. The mechanisms underlying the decline in oocyte quality associated with oocyte aging remain unknown, although studies have suggested that the decline is regulated by mitochondrial dysfunction. However, only a limited number of studies have provided direct evidence implicating mitochondrial dysfunction in oocyte quality during the aging of oocytes. We used post-ovulatory, in vivo-aged mouse oocytes as a model for studying low-quality oocytes in oocyte aging. Superovulated oocytes released from the oviduct at 14 h and 20-24 h post-hCG injection were designated as 'fresh' and 'aged' oocytes, respectively. Membrane potentials and oxygen consumption in single oocytes were evaluated as measures of mitochondrial function in fresh and aged oocytes. Mitochondrial transcriptional factor A (TFAM) expression levels were examined by western blotting, and colocalization of mitochondria and TFAM was analyzed by measuring immunofluorescence in fresh and aged oocytes. IVF and blastocyst formation rates were calculated after oocyte microinjection with mitochondria derived from liver cells. The average mitochondrial membrane potential in fresh oocytes was significantly higher than that in aged oocytes (P < 0.05). The average oxygen consumption rate in aged oocytes was significantly lower than that in fresh oocytes (P < 0.05). Although total TFAM expression was unchanged, its colocalization with mitochondria decreased in aged oocytes. IVF and blastocyst formation rates for mitochondrion-injected aged oocytes were not significantly different from those for buffer-injected aged oocytes. Not applicable. A limitation of this study is that we did not examine the effects of microinjecting mitochondria from other somatic cell types into aged oocytes on their fertilization and embryonic development rates. The results from the present study showed that poor embryonic development was associated with impairment of mitochondrial functions in in vivo-aged oocytes. However, the microinjection of mitochondria from liver cells did not improve the low fertilization and embryonic development rates of aged oocytes. It remains to be demonstrated whether oocyte quality can be rescued by the transfer of cytosolic factors or cellular organelles, such as the endoplasmic reticulum or mitochondria, from specific cell types. This study was supported by Grants-in-Aid for General Science Research to Toshifumi Takahashi (No. 25462550) and Hideki Igarashi (No. 26462474). The funding source played no role in study design in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. The authors have no conflict of interest to disclose. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Mitochondrial lipids in neurodegeneration.

PubMed

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

2017-01-01

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

A reversible component of mitochondrial respiratory dysfunction in apoptosis can be rescued by exogenous cytochrome c

PubMed Central

Mootha, Vamsi K.; Wei, Michael C.; Buttle, Karolyn F.; Scorrano, Luca; Panoutsakopoulou, Vily; Mannella, Carmen A.; Korsmeyer, Stanley J.

2001-01-01

Multiple apoptotic pathways release cytochrome c from the mitochondrial intermembrane space, resulting in the activation of downstream caspases. In vivo activation of Fas (CD95) resulted in increased permeability of the mitochondrial outer membrane and depletion of cytochrome c stores. Serial measurements of oxygen consumption, NADH redox state and membrane potential revealed a loss of respiratory state transitions. This tBID-induced respiratory failure did not require any caspase activity. At early time points, re-addition of exogenous cytochrome c markedly restored respiratory functions. Over time, however, mitochondria showed increasing irreversible respiratory dysfunction as well as diminished calcium buffering. Electron microscopy and tomographic reconstruction revealed asymmetric mitochondria with blebs of herniated matrix, distended inner membrane and partial loss of cristae structure. Thus, apoptogenic redistribution of cytochrome c is responsible for a distinct program of mitochondrial respiratory dysfunction, in addition to the activation of downstream caspases. PMID:11179211

Glutathione S-transferase mediates an ageing response to mitochondrial dysfunction

PubMed Central

Dancy, Beverley M.; Brockway, Nicole; Ramadasan-Nair, Renjini; Yang, Yoing; Sedensky, Margaret M.; Morgan, Philip G.

2016-01-01

To understand primary mitochondrial disease, we utilized a complex I-deficient Caenorhabditis elegans mutant, gas-1. These animals strongly upregulate the expression of gst-14 (encoding a glutathione S-transferase). Knockdown of gst-14 dramatically extends the lifespan of gas-1 and increases hydroxynonenal (HNE) modified mitochondrial proteins without improving complex I function. We observed no change in reactive oxygen species levels as measured by Mitosox staining, consistent with a potential role of GST-14 in HNE clearance. The upregulation of gst-14 in gas-1 animals is specific to the pharynx. These data suggest that an HNE-mediated response in the pharynx could be beneficial for lifespan extension in the context of complex I dysfunction in C. elegans. Thus, whereas HNE is typically considered damaging, our work is consistent with recent reports of its role in signaling, and that in this case, the signal is pro-longevity in a model of mitochondrial dysfunction. PMID:26704446

Inhibition of nuclear factor-κB signal by pyrrolidine dithiocarbamate alleviates lipopolysaccharide-induced acute lung injury

PubMed Central

Yang, Hongfu; Sun, Rongqing; Ma, Ning; Liu, Qilong; Sun, Xiaoge; Zi, Panpan; Wang, Junsheng; Chao, Ke; Yu, Lei

2017-01-01

This study mainly studied the effect of inhibition of nuclear factor-κB (NF-κB) signal by pyrrolidine dithiocarbamate (PDTC) on lipopolysaccharide (LPS)-induced inflammatory response, oxidative stress, and mitochondrial dysfunction in a murine acute lung injury model. The results showed that LPS exposure activated NF-κB and its upstream proteins and caused lung inflammation, oxidative stress, and mitochondrial dysfunction in mice. While inhibition of NF-κB by PDTC adminstration alleviated LPS-induced generation of lymphocytes, IL-1β, and TNF-α. Malondialdehyde, a common oxidative product, was markedly reduced after PDTC treatment in LPS-challenged mice. Furthermore, PDTC alleviated LPS-induced mitochondrial dysfunction via improving ATP synthesis and uncoupling protein 2 expression. In conclusion, inhibition of NF-κB by PDTC alleviated LPS-induced acute lung injury via maintaining inflammatory status, oxidative balance, and mitochondrial function in mice. PMID:28521300

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

PubMed Central

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

2012-01-01

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

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

PubMed Central

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

2014-01-01

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

Phosphorus and proton magnetic resonance spectroscopy demonstrates mitochondrial dysfunction in early and advanced Parkinson's disease.

PubMed

Hattingen, Elke; Magerkurth, Jörg; Pilatus, Ulrich; Mozer, Anne; Seifried, Carola; Steinmetz, Helmuth; Zanella, Friedhelm; Hilker, Rüdiger

2009-12-01

Mitochondrial dysfunction hypothetically contributes to neuronal degeneration in patients with Parkinson's disease. While several in vitro data exist, the measurement of cerebral mitochondrial dysfunction in living patients with Parkinson's disease is challenging. Anatomical magnetic resonance imaging combined with phosphorus and proton magnetic resonance spectroscopic imaging provides information about the functional integrity of mitochondria in specific brain areas. We measured partial volume corrected concentrations of low-energy metabolites and high-energy phosphates with sufficient resolution to focus on pathology related target areas in Parkinson's disease. Combined phosphorus and proton magnetic resonance spectroscopic imaging in the mesostriatal region was performed in 16 early and 13 advanced patients with Parkinson's disease and compared to 19 age-matched controls at 3 Tesla. In the putamen and midbrain of both Parkinson's disease groups, we found a bilateral reduction of high-energy phosphates such as adenosine triphophosphate and phosphocreatine as final acceptors of energy from mitochondrial oxidative phosphorylation. In contrast, low-energy metabolites such as adenosine diphophosphate and inorganic phosphate were within normal ranges. These results provide strong in vivo evidence that mitochondrial dysfunction of mesostriatal neurons is a central and persistent phenomenon in the pathogenesis cascade of Parkinson's disease which occurs early in the course of the disease.

2-Chlorohexadecanoic acid induces ER stress and mitochondrial dysfunction in brain microvascular endothelial cells.

PubMed

Bernhart, Eva; Kogelnik, Nora; Prasch, Jürgen; Gottschalk, Benjamin; Goeritzer, Madeleine; Depaoli, Maria Rosa; Reicher, Helga; Nusshold, Christoph; Plastira, Ioanna; Hammer, Astrid; Fauler, Günter; Malli, Roland; Graier, Wolfgang F; Malle, Ernst; Sattler, Wolfgang

2018-05-01

Peripheral leukocytes induce blood-brain barrier (BBB) dysfunction through the release of cytotoxic mediators. These include hypochlorous acid (HOCl) that is formed via the myeloperoxidase-H 2 O 2 -chloride system of activated phagocytes. HOCl targets the endogenous pool of ether phospholipids (plasmalogens) generating chlorinated inflammatory mediators like e.g. 2-chlorohexadecanal and its conversion product 2-chlorohexadecanoic acid (2-ClHA). In the cerebrovasculature these compounds inflict damage to brain microvascular endothelial cells (BMVEC) that form the morphological basis of the BBB. To follow subcellular trafficking of 2-ClHA we synthesized a 'clickable' alkyne derivative (2-ClHyA) that phenocopied the biological activity of the parent compound. Confocal and superresolution structured illumination microscopy revealed accumulation of 2-ClHyA in the endoplasmic reticulum (ER) and mitochondria of human BMVEC (hCMEC/D3 cell line). 2-ClHA and its alkyne analogue interfered with protein palmitoylation, induced ER-stress markers, reduced the ER ATP content, and activated transcription and secretion of interleukin (IL)-6 as well as IL-8. 2-ClHA disrupted the mitochondrial membrane potential and induced procaspase-3 and PARP cleavage. The protein kinase R-like ER kinase (PERK) inhibitor GSK2606414 suppressed 2-ClHA-mediated activating transcription factor 4 synthesis and IL-6/8 secretion, but showed no effect on endothelial barrier dysfunction and cleavage of procaspase-3. Our data indicate that 2-ClHA induces potent lipotoxic responses in brain endothelial cells and could have implications in inflammation-induced BBB dysfunction. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

NDUFA4L2 protects against ischaemia/reperfusion-induced cardiomyocyte apoptosis and mitochondrial dysfunction by inhibiting complex I.

PubMed

Li, Jianhua; Bai, Caiyan; Guo, Junxia; Liang, Wanqian; Long, Jingning

2017-07-01

Myocardial ischaemia/reperfusion (I/R) injury may cause the apoptosis of cardiomyocytes as well as mitochondrial dysfunction. The aims of the present study were to investigate whether NADH dehydrogenase 1 alpha subcomplex subunit 4-like 2 (NDUFA4L2) on myocardial ischaemia-reperfusion (I/R) injury and the underlying molecular mechanism. The hypoxia-reperfusion (H/R) model was established in vitro using H9c2 cells to simulate I/R injury. NDUFA4L2 and complex I expression levels were detected using RT-PCR and western blot. The apoptosis of H9c2 cells was evaluated by flow cytometry and the expression of Bax and Bcl-2 was detected by western blot. The mitochondrial function was assessed by ATP concentration, mPTP opening and cytochrome c (cyto C) expression. Our data indicated that NDUFA4L2 expression was significantly down-regulated in myocardial H/R injury. Overexpression of NDUFA4L2 led to a dramatic prevention of H/R-induced apoptosis accompanied by a decrease in the expression of Bax and an increase in the expression of Bcl-2. Meanwhile, augmentation of NDUFA4L2 dramatically prevented mitochondrial dysfunction caused by H/R as reflecting in the increased ATP concentration, delayed mPTP opening, as well as down-regulated cyto C expression. Moreover, complex I activation was heightened and negatively regulated by NDUFA4L2. Silencing complex I conspicuously attenuated cell apoptosis and mitochondrial dysfunction. Taken together, our findings demonstrated that NDUFA4L2 protects against H/R injury by preventing myocardium apoptosis and mitochondrial dysfunction via the complex I, and may be a potential therapeutic approach for attenuating myocardial I/R injury. © 2017 John Wiley & Sons Australia, Ltd.

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

PubMed Central

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

2013-01-01

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

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

PubMed

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

2016-10-01

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

Effect of mitochondrial dysfunction and oxidative stress on endogenous levels of coenzyme Q(10) in human cells.

PubMed

Yen, Hsiu-Chuan; Chen, Feng-Yuan; Chen, Shih-Wei; Huang, Yu-Hsiang; Chen, Yun-Ru; Chen, Chih-Wei

2011-01-01

Little is known about the regulation of endogenous CoQ(10) levels in response to mitochondrial dysfunction or oxidative stress although exogenous CoQ(10) has been extensively used in humans. In this study, we first demonstrated that acute treatment of antimycin A, an inhibitor of mitochondrial complex III, and the absence of mitochondrial DNA suppressed CoQ(10) levels in human 143B cells. Because these two conditions also enhanced formation of reactive oxygen species (ROS), we further investigated whether oxidative stress or mitochondrial dysfunction primarily contributed to the decrease of CoQ(10) levels. Results showed that H(2)O(2) augmented CoQ(10) levels, but carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), a chemical uncoupler, decreased CoQ(10) levels in 143B cells. However, H(2)O(2) and FCCP both increased mRNA levels of multiple COQ genes for biosynthesis of CoQ(10) . Our findings suggest that ROS induced CoQ(10) biosynthesis, whereas mitochondrial energy deficiency caused secondary suppression of CoQ(10) levels possibly due to impaired import of COQ proteins into mitochondria. Copyright © 2011 Wiley Periodicals, Inc.

OXPHOS-Dependent Cells Identify Environmental Disruptors of Mitochondrial Function

EPA Science Inventory

Mitochondrial dysfunction is associated with numerous chronic diseases including metabolic syndrome. Environmental chemicals can impair mitochondrial function through numerous mechanisms such as membrane disruption, complex inhibition and electron transport chain uncoupling. Curr...

Mitochondrial Approaches to Protect Against Cardiac Ischemia and Reperfusion Injury

PubMed Central

Camara, Amadou K. S.; Bienengraeber, Martin; Stowe, David F.

2011-01-01

The mitochondrion is a vital component in cellular energy metabolism and intracellular signaling processes. Mitochondria are involved in a myriad of complex signaling cascades regulating cell death vs. survival. Importantly, mitochondrial dysfunction and the resulting oxidative and nitrosative stress are central in the pathogenesis of numerous human maladies including cardiovascular diseases, neurodegenerative diseases, diabetes, and retinal diseases, many of which are related. This review will examine the emerging understanding of the role of mitochondria in the etiology and progression of cardiovascular diseases and will explore potential therapeutic benefits of targeting the organelle in attenuating the disease process. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate or manipulate mitochondrial function, to the use of light therapy directed to the mitochondrial function, and to modification of the mitochondrial genome for potential therapeutic benefit. The approach to rationally treat mitochondrial dysfunction could lead to more effective interventions in cardiovascular diseases that to date have remained elusive. The central premise of this review is that if mitochondrial abnormalities contribute to the etiology of cardiovascular diseases (e.g., ischemic heart disease), alleviating the mitochondrial dysfunction will contribute to mitigating the severity or progression of the disease. To this end, this review will provide an overview of our current understanding of mitochondria function in cardiovascular diseases as well as the potential role for targeting mitochondria with potential drugs or other interventions that lead to protection against cell injury. PMID:21559063

Mitochondrial Dysfunction in Parkinson's Disease.

PubMed

Moon, Hyo Eun; Paek, Sun Ha

2015-06-01

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

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

PubMed

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

2015-12-01

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

Developmentally regulated GTP-binding protein 2 depletion leads to mitochondrial dysfunction through downregulation of dynamin-related protein 1

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

Vo, Mai-Tram; Ko, Myoung Seok; Lee, Unn Hwa

Mitochondrial dynamics, including constant fusion and fission, play critical roles in maintaining mitochondrial morphology and function. Here, we report that developmentally regulated GTP-binding protein 2 (DRG2) regulates mitochondrial morphology by modulating the expression of the mitochondrial fission gene dynamin-related protein 1 (Drp1). shRNA-mediated silencing of DRG2 induced mitochondrial swelling, whereas expression of an shRNA-resistant version of DRG2 decreased mitochondrial swelling in DRG2-depleted cells. Analysis of the expression levels of genes involved in mitochondrial fusion and fission revealed that DRG2 depletion significantly decreased the level of Drp1. Overexpression of Drp1 rescued the defect in mitochondrial morphology induced by DRG2 depletion. DRG2more » depletion reduced the mitochondrial membrane potential, oxygen consumption rate (OCR), and amount of mitochondrial DNA (mtDNA), whereas it increased reactive oxygen species (ROS) production and apoptosis. Taken together, our data demonstrate that DRG2 acts as a regulator of mitochondrial fission by controlling the expression of Drp1. - Highlights: • DRG2 depletion increased mitochondrial swelling. • DRG2 depletion inhibited the expression of Drp1. • Overexpression of DRG2 or Drp1 rescued mitochondrial shape in DRG2 depleted cells. • DRG2 depletion induced mitochondrial dysfunction.« less

Investigating mitochondrial dysfunction in human lung cells exposed to redox-active PM components.

PubMed

Lavrich, Katelyn S; Corteselli, Elizabeth M; Wages, Phillip A; Bromberg, Philip A; Simmons, Steven O; Gibbs-Flournoy, Eugene A; Samet, James M

2018-03-01

Exposure to ambient particulate matter (PM) causes cardiopulmonary morbidity and mortality through mechanisms that involve oxidative stress. 1,2-naphthoquinone (1,2-NQ) is a ubiquitous component of PM and a potent redox-active electrophile. We previously reported that 1,2-NQ increases mitochondrial H 2 O 2 production through an unidentified mechanism. We sought to characterize the effects of 1,2-NQ exposure on mitochondrial respiration as a source of H 2 O 2 in human airway epithelial cells. We measured the effects of acute exposure to 1,2-NQ on oxygen consumption rate (OCR) in the human bronchial epithelial cell line BEAS-2B and mitochondrial preparations using extracellular flux analysis. Complex-specific assays and NADPH depletion by glucose deprivation distinguished between mitochondrial and non-mitochondrial oxygen utilization. 1,2-NQ exposure of BEAS cells caused a rapid, marked dose-dependent increase in OCR that was independent of mitochondrial respiration, exceeded the OCR observed after mitochondrial uncoupling, and remained sensitive to NADPH depletion, implicating extra-mitochondrial redox cycling processes. Similar effects were observed with the environmentally relevant redox-cycling quinones 1,4-naphthoquinone and 9,10-phenanthrenequinone, but not with quinones that do not redox cycle, such as 1,4-benzoquinone. In mitochondrial preparations, 1,2-NQ caused a decrease in Complex I-linked substrate oxidation, suggesting impairment of pyruvate utilization or transport, a novel mechanism of mitochondrial inhibition by an environmental exposure. This study also highlights the methodological utility and challenges in the use of extracellular flux analysis to elucidate the mechanisms of action of redox-active electrophiles present in ambient air. Published by Elsevier Inc.

Mitochondrial Respiratory Chain Dysfunction in Dorsal Root Ganglia of Streptozotocin-Induced Diabetic Rats and Its Correction by Insulin Treatment

PubMed Central

Chowdhury, Subir K. Roy; Zherebitskaya, Elena; Smith, Darrell R.; Akude, Eli; Chattopadhyay, Sharmila; Jolivalt, Corinne G.; Calcutt, Nigel A.; Fernyhough, Paul

2010-01-01

OBJECTIVE Impairments in mitochondrial physiology may play a role in diabetic sensory neuropathy. We tested the hypothesis that mitochondrial dysfunction in sensory neurons is due to abnormal mitochondrial respiratory function. RESEARCH DESIGN AND METHODS Rates of oxygen consumption were measured in mitochondria from dorsal root ganglia (DRG) of 12- to- 22-week streptozotocin (STZ)-induced diabetic rats, diabetic rats treated with insulin, and age-matched controls. Activities and expression of components of mitochondrial complexes and reactive oxygen species (ROS) were analyzed. RESULTS Rates of coupled respiration with pyruvate + malate (P + M) and with ascorbate + TMPD (Asc + TMPD) in DRG were unchanged after 12 weeks of diabetes. By 22 weeks of diabetes, respiration with P + M was significantly decreased by 31–44% and with Asc + TMPD by 29–39% compared with control. Attenuated mitochondrial respiratory activity of STZ-diabetic rats was significantly improved by insulin that did not correct other indices of diabetes. Activities of mitochondrial complexes I and IV and the Krebs cycle enzyme, citrate synthase, were decreased in mitochondria from DRG of 22-week STZ-diabetic rats compared with control. ROS levels in perikarya of DRG neurons were not altered by diabetes, but ROS generation from mitochondria treated with antimycin A was diminished compared with control. Reduced mitochondrial respiratory function was associated with downregulation of expression of mitochondrial proteins. CONCLUSIONS Mitochondrial dysfunction in sensory neurons from type 1 diabetic rats is associated with impaired rates of respiratory activity and occurs without a significant rise in perikaryal ROS. PMID:20103706

Assessment of Mitochondrial Dysfunction Arising from Treatment with Hepatotoxicants

PubMed Central

King, Adrienne L.; Bailey, Shannon M.

2010-01-01

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

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

PubMed

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

2018-03-01

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

PGAM5 regulates PINK1/Parkin-mediated mitophagy via DRP1 in CCCP-induced mitochondrial dysfunction.

PubMed

Park, Yun Sun; Choi, Su Eun; Koh, Hyun Chul

2018-03-01

Mitochondrial dynamics and mitophagy are critical processes for regulating mitochondrial homeostasis. Phosphoglycerate mutase family member 5 (PGAM5) is a mitochondrial protein that plays crucial roles in apoptosis and necroptosis, but the roles of PGAM5 in mitochondrial dynamics and mitophagy remain unclear. In this study, we investigated the role of PGAM5 in carbonyl cyanide m-chlorophenylhydrazone (CCCP)-induced mitochondrial damage and the correlation between mitochondrial dynamics and mitophagy using SH-SY5Y cells. We found that CCCP decreased mitochondrial membrane potential, resulting in mitochondrial dysfunction. CCCP increased PGAM5, dynamin-related protein 1 (DRP1), and optic atrophy 1 (OPA1) expression of the mitochondrial fraction in a time-dependent manner. Knockdown of PGAM5 inhibited DRP1 translocation without a change in OPA1 expression in CCCP-treated cells. Furthermore, knockdown of PGAM5 and DRP1 significantly blocked the increase of PTEN-induced putative protein kinase 1 (PINK1) and Parkin expression in the mitochondrial fraction of CCCP-treated cells. Interestingly, CCCP did not alter PINK1/Parkin expression in the mitochondrial fraction of OPA1 knockdown cells. Inhibiting mitophagy by PGAM5 knockdown accelerated CCCP-induced apoptosis. CCCP treatment also results in PINK1 stabilization on the mitochondrial membrane, which subsequently increases Parkin recruitment from the cytosol to abnormal mitochondria. In addition, we found that CCCP increased the level of mitochondrial LC3II, indicating that Parkin recruitment of PINK1 is a result of mitophagy. We propose that activation of PGAM5 is associated with DRP1 recruitment and PINK1 stabilization, which contribute to the modulation of mitophagy in CCCP-treated cells with mitochondrial dysfunction. In conclusion, we demonstrated that PGAM5 regulates PINK1-Parkin-mediated mitophagy, which can exert a neuroprotective effect against CCCP-induced apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Lactate shuttling and lactate use as fuel after traumatic brain injury: metabolic considerations

PubMed Central

Dienel, Gerald A

2014-01-01

Lactate is proposed to be generated by astrocytes during glutamatergic neurotransmission and shuttled to neurons as ‘preferred' oxidative fuel. However, a large body of evidence demonstrates that metabolic changes during activation of living brain disprove essential components of the astrocyte–neuron lactate shuttle model. For example, some glutamate is oxidized to generate ATP after its uptake into astrocytes and neuronal glucose phosphorylation rises during activation and provides pyruvate for oxidation. Extension of the notion that lactate is a preferential fuel into the traumatic brain injury (TBI) field has important clinical implications, and the concept must, therefore, be carefully evaluated before implementation into patient care. Microdialysis studies in TBI patients demonstrate that lactate and pyruvate levels and lactate/pyruvate ratios, along with other data, have important diagnostic value to distinguish between ischemia and mitochondrial dysfunction. Results show that lactate release from human brain to blood predominates over its uptake after TBI, and strong evidence for lactate metabolism is lacking; mitochondrial dysfunction may inhibit lactate oxidation. Claims that exogenous lactate infusion is energetically beneficial for TBI patients are not based on metabolic assays and data are incorrectly interpreted. PMID:25204393

Mitochondrial Reactive Oxygen Species Mediate Cardiac Structural, Functional, and Mitochondrial Consequences of Diet-Induced Metabolic Heart Disease.

PubMed

Sverdlov, Aaron L; Elezaby, Aly; Qin, Fuzhong; Behring, Jessica B; Luptak, Ivan; Calamaras, Timothy D; Siwik, Deborah A; Miller, Edward J; Liesa, Marc; Shirihai, Orian S; Pimentel, David R; Cohen, Richard A; Bachschmid, Markus M; Colucci, Wilson S

2016-01-11

Mitochondrial reactive oxygen species (ROS) are associated with metabolic heart disease (MHD). However, the mechanism by which ROS cause MHD is unknown. We tested the hypothesis that mitochondrial ROS are a key mediator of MHD. Mice fed a high-fat high-sucrose (HFHS) diet develop MHD with cardiac diastolic and mitochondrial dysfunction that is associated with oxidative posttranslational modifications of cardiac mitochondrial proteins. Transgenic mice that express catalase in mitochondria and wild-type mice were fed an HFHS or control diet for 4 months. Cardiac mitochondria from HFHS-fed wild-type mice had a 3-fold greater rate of H2O2 production (P=0.001 versus control diet fed), a 30% decrease in complex II substrate-driven oxygen consumption (P=0.006), 21% to 23% decreases in complex I and II substrate-driven ATP synthesis (P=0.01), and a 62% decrease in complex II activity (P=0.002). In transgenic mice that express catalase in mitochondria, all HFHS diet-induced mitochondrial abnormalities were ameliorated, as were left ventricular hypertrophy and diastolic dysfunction. In HFHS-fed wild-type mice complex II substrate-driven ATP synthesis and activity were restored ex vivo by dithiothreitol (5 mmol/L), suggesting a role for reversible cysteine oxidative posttranslational modifications. In vitro site-directed mutation of complex II subunit B Cys100 or Cys103 to redox-insensitive serines prevented complex II dysfunction induced by ROS or high glucose/high palmitate in the medium. Mitochondrial ROS are pathogenic in MHD and contribute to mitochondrial dysfunction, at least in part, by causing oxidative posttranslational modifications of complex I and II proteins including reversible oxidative posttranslational modifications of complex II subunit B Cys100 and Cys103. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

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

PubMed Central

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

2013-01-01

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

A specific amino acid formula prevents alcoholic liver disease in rodents.

PubMed

Tedesco, Laura; Corsetti, Giovanni; Ruocco, Chiara; Ragni, Maurizio; Rossi, Fabio; Carruba, Michele O; Valerio, Alessandra; Nisoli, Enzo

2018-05-01

Chronic alcohol consumption promotes mitochondrial dysfunction, oxidative stress, defective protein metabolism, and fat accumulation in hepatocytes (liver steatosis). Inadequate amino acid metabolism is worsened by protein malnutrition, frequently present in alcohol-consuming patients, with reduced circulating branched-chain amino acids (BCAAs). Here we asked whether dietary supplementation with a specific amino acid mixture, enriched in BCAAs (BCAAem) and able to promote mitochondrial function in muscle of middle-aged rodents, would prevent mitochondrial dysfunction and liver steatosis in Wistar rats fed on a Lieber-DeCarli ethanol (EtOH)-containing liquid diet. Supplementation of BCAAem, unlike a mixture based on the amino acid profile of casein, abrogated the EtOH-induced fat accumulation, mitochondrial impairment, and oxidative stress in liver. These effects of BCAAem were accompanied by normalization of leucine, arginine, and tryptophan levels, which were reduced in liver of EtOH-consuming rats. Moreover, although the EtOH exposure of HepG2 cells reduced mitochondrial DNA, mitochondrial transcription factors, and respiratory chain proteins, the BCAAem but not casein-derived amino acid supplementation halted this mitochondrial toxicity. Nicotinamide adenine dinucleotide levels and sirtuin 1 (Sirt1) expression, as well as endothelial nitric oxide (eNOS) and mammalian/mechanistic target of rapamycin (mTOR) signaling pathways, were downregulated in the EtOH-exposed HepG2 cells. BCAAem reverted these molecular defects and the mitochondrial dysfunction, suggesting that the mitochondrial integrity obtained with the amino acid supplementation could be mediated through a Sirt1-eNOS-mTOR pathway. Thus a dietary activation of the mitochondrial biogenesis and function by a specific amino acid supplement protects against the EtOH toxicity and preserves the liver integrity in mammals. NEW & NOTEWORTHY Dietary supplementation of a specific amino acid formula prevents both fat accumulation and mitochondrial dysfunction in hepatocytes of alcohol-consuming rats. These effects are accompanied also by increased expression of anti-reactive oxygen species genes. The amino acid-protective effects likely reflect activation of sirtuin 1-endothelial nitric oxide synthase-mammalian target of rapamycin pathway able to regulate the cellular energy balance of hepatocytes exposed to chronic, alcoholic damage.

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

PubMed

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

2016-01-01

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

Low anaerobic threshold and increased skeletal muscle lactate production in subjects with Huntington's disease.

PubMed

Ciammola, Andrea; Sassone, Jenny; Sciacco, Monica; Mencacci, Niccolò E; Ripolone, Michela; Bizzi, Caterina; Colciago, Clarissa; Moggio, Maurizio; Parati, Gianfranco; Silani, Vincenzo; Malfatto, Gabriella

2011-01-01

Mitochondrial defects that affect cellular energy metabolism have long been implicated in the etiology of Huntington's disease (HD). Indeed, several studies have found defects in the mitochondrial functions of the central nervous system and peripheral tissues of HD patients. In this study, we investigated the in vivo oxidative metabolism of exercising muscle in HD patients. Ventilatory and cardiometabolic parameters and plasma lactate concentrations were monitored during incremental cardiopulmonary exercise in twenty-five HD subjects and twenty-five healthy subjects. The total exercise capacity was normal in HD subjects but notably the HD patients and presymptomatic mutation carriers had a lower anaerobic threshold than the control subjects. The low anaerobic threshold of HD patients was associated with an increase in the concentration of plasma lactate. We also analyzed in vitro muscular cell cultures and found that HD cells produce more lactate than the cells of healthy subjects. Finally, we analyzed skeletal muscle samples by electron microscopy and we observed striking mitochondrial structural abnormalities in two out of seven HD subjects. Our findings confirm mitochondrial abnormalities in HD patients' skeletal muscle and suggest that the mitochondrial dysfunction is reflected functionally in a low anaerobic threshold and an increased lactate synthesis during intense physical exercise. Copyright © 2010 Movement Disorder Society.

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

PubMed

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

2004-02-01

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

The Whitening of Brown Fat and Its Implications for Weight Management in Obesity.

PubMed

Shimizu, Ippei; Walsh, Kenneth

2015-06-01

Systemic inflammation resulting from dysfunction of white adipose tissue (WAT) accelerates the pathologies of diabetes and cardiovascular diseases. In contrast to WAT, brown adipose tissue (BAT) is abundant in mitochondria that produce heat by uncoupling respiratory chain process of ATP synthesis. Besides BAT's role in thermogenesis, accumulating evidence has shown that it is involved in regulating systemic metabolism. Studies have analyzed the "browning" processes of WAT as a means to combat obesity, whereas few studies have focused on the impact and molecular mechanisms that contribute to obesity-linked BAT dysfunction--a process that is associated with the "whitening" of this tissue. Compared to WAT, a dense vascular network is required to support the high energy consumption of BAT. Recently, vascular rarefaction was shown to be a significant causal factor in the whitening of BAT in mouse models. Vascular insufficiency leads to mitochondrial dysfunction and loss in BAT and contributes to systemic insulin resistance. These data suggest that BAT "whitening," resulting from vascular dysfunction, can impact obesity and obesity-linked diseases. Conversely, agents that promote BAT function could have utility in the treatment of these conditions.

The optic nerve: A “mito-window” on mitochondrial neurodegeneration

PubMed Central

Maresca, Alessandra; la Morgia, Chiara; Caporali, Leonardo; Valentino, Maria Lucia; Carelli, Valerio

2013-01-01

Retinal ganglion cells (RGCs) project their long axons, composing the optic nerve, to the brain, transmitting the visual information gathered by the retina, ultimately leading to formed vision in the visual cortex. The RGC cellular system, representing the anterior part of the visual pathway, is vulnerable to mitochondrial dysfunction and optic atrophy is a very frequent feature of mitochondrial and neurodegenerative diseases. The start of the molecular era of mitochondrial medicine, the year 1988, was marked by the identification of a maternally inherited form of optic atrophy, Leber's hereditary optic neuropathy, as the first disease due to mitochondrial DNA point mutations. The field of mitochondrial medicine has expanded enormously over the last two decades and many neurodegenerative diseases are now known to have a primary mitochondrial etiology or mitochondrial dysfunction plays a relevant role in their pathogenic mechanism. Recent technical advancements in neuro-ophthalmology, such as optical coherence tomography, prompted a still ongoing systematic re-investigation of retinal and optic nerve involvement in neurodegenerative disorders. In addition to inherited optic neuropathies, such as Leber's hereditary optic neuropathy and dominant optic atrophy, and in addition to the syndromic mitochondrial encephalomyopathies or mitochondrial neurodegenerative disorders such as some spinocerebellar ataxias or familial spastic paraparesis and other disorders, we draw attention to the involvement of the optic nerve in classic age-related neurodegenerative disorders such as Parkinson and Alzheimer disease. We here provide an overview of optic nerve pathology in these different clinical settings, and we review the possible mechanisms involved in the pathogenesis of optic atrophy. This may be a model of general value for the field of neurodegeneration. This article is part of a Special Issue entitled ‘Mitochondrial function and dysfunction in neurodegeneration’. PMID:22960139

The mitochondrially targeted antioxidant MitoQ protects the intestinal barrier by ameliorating mitochondrial DNA damage via the Nrf2/ARE signaling pathway.

PubMed

Hu, Qiongyuan; Ren, Jianan; Li, Guanwei; Wu, Jie; Wu, Xiuwen; Wang, Gefei; Gu, Guosheng; Ren, Huajian; Hong, Zhiwu; Li, Jieshou

2018-03-14

Disruption of the mucosal barrier following intestinal ischemia reperfusion (I/R) is life threatening in clinical practice. Mitochondrial dysfunction and oxidative stress significantly contribute to the early phase of I/R injury and amplify the inflammatory response. MitoQ is a mitochondrially targeted antioxidant that exerts protective effects following I/R injury. In the present study, we aimed to determine whether and how MitoQ protects intestinal epithelial cells (IECs) from I/R injury. In both in vivo and in vitro studies, we found that MitoQ pretreatment downregulated I/R-induced oxidative stress and stabilized the intestinal barrier, as evidenced by MitoQ-treated I/R mice exhibiting attenuated intestinal hyperpermeability, inflammatory response, epithelial apoptosis, and tight junction damage compared to controls. Mechanistically, I/R elevated mitochondrial 8-hydroxyguanine content, reduced mitochondrial DNA (mtDNA) copy number and mRNA transcription levels, and induced mitochondrial disruption in IECs. However, MitoQ pretreatment dramatically inhibited these deleterious effects. mtDNA depletion alone was sufficient to induce apoptosis and mitochondrial dysfunction of IECs. Mitochondrial transcription factor A (TFAM), a key activator of mitochondrial transcription, was significantly reduced during I/R injury, a phenomenon that was prevented by MitoQ treatment. Furthermore, we observed that thee protective properties of MitoQ were affected by upregulation of cellular antioxidant genes, including HO-1, NQO-1, and γ-GCLC. Transfection with Nrf2 siRNA in IECs exposed to hypoxia/reperfusion conditions partially blocked the effects of MitoQ on mtDNA damage and mitochondrial oxidative stress. In conclusion, our data suggest that MitoQ exerts protective effect on I/R-induced intestinal barrier dysfunction.

Brain-mediated dysregulation of the bone marrow activity in angiotensin II-induced hypertension.

PubMed

Jun, Joo Yun; Zubcevic, Jasenka; Qi, Yanfei; Afzal, Aqeela; Carvajal, Jessica Marulanda; Thinschmidt, Jeffrey S; Grant, Maria B; Mocco, J; Raizada, Mohan K

2012-11-01

Oxidative stress in the brain is implicated in increased sympathetic drive, inflammatory status, and vascular dysfunctions, associated with development and establishment of hypertension. However, little is known about the mechanism of this impaired brain-vascular communication. Here, we tested the hypothesis that increased oxidative stress in the brain cardioregulatory areas, such as the paraventricular nucleus of the hypothalamus, is driven by mitochondrial reactive oxygen species and leads to increased inflammatory cells (ICs) and decreased/dysfunctional endothelial progenitor cells (EPCs), thereby compromising vasculature repair and accelerating hypertension. Chronic angiotensin II infusion resulted in elevated blood pressure and sympathetic vasomotor drive, decreased spontaneous baroreflex gain, and increased microglia activation in the paraventricular nucleus. This was associated with 46% decrease in bone marrow (BM)-derived EPCs and 250% increase in BM ICs, resulting in 5-fold decrease of EPC/IC ratio in the BM. Treatment with mitochondrial-targeted antioxidant, a scavenger of mitochondrial O(2)(-·), intracerebroventricularly but not subcutaneously attenuated angiotensin II-induced hypertension, decreased activation of microglia in the paraventricular nucleus, and normalized EPCs/ICs. This functional communication between the brain and BM was confirmed by retrograde neuronal labeling from the BM with green fluorescent protein-tagged pseudorabies virus. Administration of green fluorescent protein-tagged pseudorabies virus into the BM resulted in predominant labeling of paraventricular nucleus neurons within 3 days, with some fluorescence in the nucleus tractus solitarius, the rostral ventrolateral medulla, and subfornical organ. Taken together, these data demonstrate that inhibition of mitochondrial reactive oxygen species attenuates angiotensin II-induced hypertension and corrects the imbalance in EPCs/ICs in the BM. They suggest that an imbalance in vascular reparative and ICs may perpetuate vascular pathophysiology in this model of hypertension.

Neuroprotective efficacy of naringin on 3-nitropropionic acid-induced mitochondrial dysfunction through the modulation of Nrf2 signaling pathway in PC12 cells.

PubMed

Kulasekaran, Gopinath; Ganapasam, Sudhandiran

2015-11-01

Oxidative stress and mitochondrial dysfunction are implicated in neuronal apoptosis associated with Huntington's disease. Naringin is the flavanone present in grapefruit and related citrus species possess diverse pharmacological and therapeutic properties including antioxidant, anti-apoptotic, and neuroprotective properties. The aim of this study was to investigate the protective effect of naringin on 3-nitropropionic acid (3-NP)-induced neurotoxicity in pheochromocytoma cells (PC12) cells and to explore its mechanism of action. Naringin protects PC12 cells from 3-NP neurotoxicity, as evaluated the by cell viability assays. The lactate dehydrogenase release was decreased upon naringin treatment in 3-NP-induced PC12 cells. Naringin treatment enhances the antioxidant defense by increasing the activities of enzymatic antioxidants and the level of reduced glutathione. The increase in levels of reactive oxygen species and lipid peroxidation induced by 3-NP were significantly decreased by naringin. PC12 cells induced with 3-NP showed decrease in the mitochondrial membrane potential and mitochondrial respiratory complex enzymes, succinate dehydrogenase and cytochrome c oxidase activities, and it was significantly altered to near normal upon naringin treatment. Naringin reduced the 3-NP-induced apoptosis through the modulation in expressions of B-cell lymphoma 2 and Bcl-2-associated X protein. Further, naringin enhances the nuclear translocation of Nrf2 and induces the quinone oxidoreductase-1 and Heme oxygenase-1 expressions through the phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway. Taken together, the above findings suggest that naringin augments cellular antioxidant defense capacity and reduces the 3-NP-induced neurotoxicity in PC12 cells through the PI-3K/Akt-dependent Nrf2 activation in PC12 cells.

Mitochondrial Fission Triggered by Hyperglycemia Is Mediated by ROCK1 Activation in Podocytes and Endothelial Cells

PubMed Central

Wang, Wenjian; Wang, Yin; Long, Jianyin; Wang, Jinrong; Haudek, Sandra B.; Overbeek, Paul; Chang, Benny H.J.; Schumacker, Paul T.; Danesh, Farhad R.

2012-01-01

SUMMARY Several lines of evidence suggest that mitochondrial dysfunction plays a critical role in the pathogenesis of microvascular complications of diabetes, including diabetic nephropathy. However, the signaling pathways by which hyperglycemia leads to mitochondrial dysfunction are not fully understood. Here we examined the role of Rho-associated coiled-coil containing protein kinase 1 (ROCK1) on mitochondrial dynamics by generating two diabetic mouse models with targeted deletions of ROCK1, and an inducible podocyte-specific knock-in mouse expressing a constitutively active (cA) mutant of ROCK1. Our findings suggest that ROCK1 mediates hyperglycemia-induced mitochondrial fission by promoting dynamin-related protein-1 (Drp1) recruitment to the mitochondria. Deletion of ROCK1 in diabetic mice prevented mitochondrial fission, whereas podocyte-specific cA-ROCK1 mice exhibited increased mitochondrial fission. Importantly, we found that ROCK1 triggers mitochondrial fission by phosphorylating Drp1 at Serine 600 residue. These findings provide insights into the unexpected role of ROCK1 in a signaling cascade that regulates mitochondrial dynamics. PMID:22326220

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

MITOCHONDRIA-TARGETED ANTIOXIDANTS FOR TREATMENT OF PARKINSON’S DISEASE: PRECLINICAL AND CLINICAL OUTCOMES

PubMed Central

Jin, Huajun; Kanthasamy, Arthi; Ghosh, Anamitra; Anantharam, Vellareddy; Kalyanaraman, Balaraman; Kanthasamy, Anumantha G.

2013-01-01

Parkinson’s disease (PD) is a progressive neurodegenerative disease in the elderly, and no cure or disease-modifying therapies exist. Several lines of evidence suggest that mitochondrial dysfunction and oxidative stress have a central role in the dopaminergic neurodegeneration of PD. In this context, mitochondria-targeted therapies that improve mitochondrial function may have great promise in the prevention and treatment of PD. In this review, we discuss the recent developments in mitochondria-targeted antioxidants and their potential beneficial effects as a therapy for ameliorating mitochondrial dysfunction in PD. PMID:24060637

Tryptamine-gallic acid hybrid prevents non-steroidal anti-inflammatory drug-induced gastropathy: correction of mitochondrial dysfunction and inhibition of apoptosis in gastric mucosal cells.

PubMed

Pal, Chinmay; Bindu, Samik; Dey, Sumanta; Alam, Athar; Goyal, Manish; Iqbal, Mohd Shameel; Sarkar, Souvik; Kumar, Rahul; Halder, Kamal Krishna; Debnath, Mita Chatterjee; Adhikari, Susanta; Bandyopadhyay, Uday

2012-01-27

We have investigated the gastroprotective effect of SEGA (3a), a newly synthesized tryptamine-gallic acid hybrid molecule against non-steroidal anti-inflammatory drug (NSAID)-induced gastropathy with mechanistic details. SEGA (3a) prevents indomethacin (NSAID)-induced mitochondrial oxidative stress (MOS) and dysfunctions in gastric mucosal cells, which play a pathogenic role in inducing gastropathy. SEGA (3a) offers this mitoprotective effect by scavenging of mitochondrial superoxide anion (O(2)(·-)) and intramitochondrial free iron released as a result of MOS. SEGA (3a) in vivo blocks indomethacin-mediated MOS, as is evident from the inhibition of indomethacin-induced mitochondrial protein carbonyl formation, lipid peroxidation, and thiol depletion. SEGA (3a) corrects indomethacin-mediated mitochondrial dysfunction in vivo by restoring defective electron transport chain function, collapse of transmembrane potential, and loss of dehydrogenase activity. SEGA (3a) not only corrects mitochondrial dysfunction but also inhibits the activation of the mitochondrial pathway of apoptosis by indomethacin. SEGA (3a) inhibits indomethacin-induced down-regulation of bcl-2 and up-regulation of bax genes in gastric mucosa. SEGA (3a) also inhibits indometacin-induced activation of caspase-9 and caspase-3 in gastric mucosa. Besides the gastroprotective effect against NSAID, SEGA (3a) also expedites the healing of already damaged gastric mucosa. Radiolabeled ((99m)Tc-labeled SEGA (3a)) tracer studies confirm that SEGA (3a) enters into mitochondria of gastric mucosal cell in vivo, and it is quite stable in serum. Thus, SEGA (3a) bears an immense potential to be a novel gastroprotective agent against NSAID-induced gastropathy.

Renal mitochondrial dysfunction in spontaneously hypertensive rats is attenuated by losartan but not by amlodipine.

PubMed

de Cavanagh, Elena M V; Toblli, Jorge E; Ferder, León; Piotrkowski, Bárbara; Stella, Inés; Inserra, Felipe

2006-06-01

Mitochondrial dysfunction is associated with cardiovascular damage; however, data on a possible association with kidney damage are scarce. Here, we aimed at investigating whether 1) kidney impairment is related to mitochondrial dysfunction; and 2) ANG II blockade, compared with Ca2+ channel blockade, can reverse potential mitochondrial changes in hypertension. Eight-week-old male spontaneously hypertensive rats (SHR) received water containing losartan (40 mg.kg-1.day-1, SHR+Los), amlodipine (3 mg.kg-1.day-1, SHR+Amlo), or no additions (SHR) for 6 mo. Wistar-Kyoto rats (WKY) were normotensive controls. Glomerular and tubulointerstitial damage, systolic blood pressure, and proteinuria were higher, and creatinine clearance was lower in SHR vs. SHR+Los and WKY. In SHR+Amlo, blood pressure was similar to WKY, kidney function was similar to SHR, and renal lesions were lower than in SHR, but higher than in SHR+Los. In kidney mitochondria from SHR and SHR+Amlo, membrane potential, nitric oxide synthase, manganese-superoxide dismutase and cytochrome oxidase activities, and uncoupling protein-2 content were lower than in SHR+Los and WKY. In SHR and SHR+Amlo, mitochondrial H2O2 production was higher than in SHR+Los and WKY. Renal glutathione content was lower in SHR+Amlo relative to SHR, SHR+Los, and WKY. In SHR and SHR+Amlo, glutathione was relatively more oxidized than in SHR+Los and WKY. Tubulointerstitial alpha-smooth muscle actin labeling was inversely related to manganese-superoxide dismutase activity and uncoupling protein-2 content. These findings suggest that oxidant stress is associated with renal mitochondrial dysfunction in SHR. The mitochondrial-antioxidant actions of losartan may be an additional or alternative way to explain some of the beneficial effects of AT1-receptor antagonists.

Menadione-Induced DNA Damage Leads to Mitochondrial Dysfunction and Fragmentation During Rosette Formation in Fuchs Endothelial Corneal Dystrophy

PubMed Central

Halilovic, Adna; Schmedt, Thore; Benischke, Anne-Sophie; Hamill, Cecily; Chen, Yuming; Santos, Janine Hertzog

2016-01-01

Abstract Aims: Fuchs endothelial corneal dystrophy (FECD), a leading cause of age-related corneal edema requiring transplantation, is characterized by rosette formation of corneal endothelium with ensuing apoptosis. We sought to determine whether excess of mitochondrial reactive oxygen species leads to chronic accumulation of oxidative DNA damage and mitochondrial dysfunction, instigating cell death. Results: We modeled the pathognomonic rosette formation of postmitotic corneal cells by increasing endogenous cellular oxidative stress with menadione (MN) and performed a temporal analysis of its effect in normal (HCEnC, HCECi) and FECD (FECDi) cells and ex vivo specimens. FECDi and FECD ex vivo specimens exhibited extensive mtDNA and nDNA damage as detected by quantitative PCR. Exposure to MN triggered an increase in mitochondrial superoxide levels and led to mtDNA and nDNA damage, while DNA amplification was restored with NAC pretreatment. Furthermore, MN exposure led to a decrease in ΔΨm and adenosine triphosphate levels in normal cells, while FECDi exhibited mitochondrial dysfunction at baseline. Mitochondrial fragmentation and cytochrome c release were detected in FECD tissue and after MN treatment of HCEnCs. Furthermore, cleavage of caspase-9 and caspase-3 followed MN-induced cytochrome c release in HCEnCs. Innovation: This study provides the first line of evidence that accumulation of oxidative DNA damage leads to rosette formation, loss of functionally intact mitochondria via fragmentation, and subsequent cell death during postmitotic cell degeneration of ocular tissue. Conclusion: MN induced rosette formation, along with mtDNA and nDNA damage, mitochondrial dysfunction, and fragmentation, leading to activation of the intrinsic apoptosis via caspase cleavage and cytochrome c release. Antioxid. Redox Signal. 24, 1072–1083. PMID:26935406

Menadione-Induced DNA Damage Leads to Mitochondrial Dysfunction and Fragmentation During Rosette Formation in Fuchs Endothelial Corneal Dystrophy.

PubMed

Halilovic, Adna; Schmedt, Thore; Benischke, Anne-Sophie; Hamill, Cecily; Chen, Yuming; Santos, Janine Hertzog; Jurkunas, Ula V

2016-06-20

Fuchs endothelial corneal dystrophy (FECD), a leading cause of age-related corneal edema requiring transplantation, is characterized by rosette formation of corneal endothelium with ensuing apoptosis. We sought to determine whether excess of mitochondrial reactive oxygen species leads to chronic accumulation of oxidative DNA damage and mitochondrial dysfunction, instigating cell death. We modeled the pathognomonic rosette formation of postmitotic corneal cells by increasing endogenous cellular oxidative stress with menadione (MN) and performed a temporal analysis of its effect in normal (HCEnC, HCECi) and FECD (FECDi) cells and ex vivo specimens. FECDi and FECD ex vivo specimens exhibited extensive mtDNA and nDNA damage as detected by quantitative PCR. Exposure to MN triggered an increase in mitochondrial superoxide levels and led to mtDNA and nDNA damage, while DNA amplification was restored with NAC pretreatment. Furthermore, MN exposure led to a decrease in ΔΨm and adenosine triphosphate levels in normal cells, while FECDi exhibited mitochondrial dysfunction at baseline. Mitochondrial fragmentation and cytochrome c release were detected in FECD tissue and after MN treatment of HCEnCs. Furthermore, cleavage of caspase-9 and caspase-3 followed MN-induced cytochrome c release in HCEnCs. This study provides the first line of evidence that accumulation of oxidative DNA damage leads to rosette formation, loss of functionally intact mitochondria via fragmentation, and subsequent cell death during postmitotic cell degeneration of ocular tissue. MN induced rosette formation, along with mtDNA and nDNA damage, mitochondrial dysfunction, and fragmentation, leading to activation of the intrinsic apoptosis via caspase cleavage and cytochrome c release. Antioxid. Redox Signal. 24, 1072-1083.

Mitochondrial mechanisms of neuronal rescue by F-68, a hydrophilic Pluronic block co-polymer, following acute substrate deprivation.

PubMed

Wang, Janice C; Bindokas, Vytautas P; Skinner, Matthew; Emrick, Todd; Marks, Jeremy D

2017-10-01

Global brain ischemia can lead to widespread neuronal death and poor neurologic outcomes in patients. Despite detailed understanding of the cellular and molecular mechanisms mediating neuronal death following focal and global brain hypoxia-ischemia, treatments to reduce ischemia-induced brain injury remain elusive. One pathway central to neuronal death following global brain ischemia is mitochondrial dysfunction, one consequence of which is the cascade of intracellular events leading to mitochondrial outer membrane permeabilization. A novel approach to rescuing injured neurons from death involves targeting cellular membranes using a class of synthetic molecules called Pluronics. Pluronics are triblock copolymers of hydrophilic poly[ethylene oxide] (PEO) and hydrophobic poly[propylene oxide] (PPO). Evidence is accumulating to suggest that hydrophilic Pluronics rescue injured neurons from death following substrate deprivation by preventing mitochondrial dysfunction. Here, we will review current understanding of the nature of interaction of Pluronic molecules with biological membranes and the efficacy of F-68, an 80% hydrophilic Pluronic, in rescuing neurons from injury. We will review data indicating that F-68 reduces mitochondrial dysfunction and mitochondria-dependent death pathways in a model of neuronal injury in vitro, and present new evidence that F-68 acts directly on mitochondria to inhibit mitochondrial outer membrane permeabilization. Finally, we will present results of a pilot, proof-of-principle study suggesting that F-68 is effective in reducing hippocampal injury induced by transient global ischemia in vivo. By targeting mitochondrial dysfunction, F-68 and other Pluronic molecules constitute an exciting new approach to rescuing neurons from acute injury. Copyright © 2017 Elsevier Ltd. All rights reserved.

IGF-1 Alleviates High Fat Diet-Induced Myocardial Contractile Dysfunction: Role of Insulin Signaling and Mitochondrial Function

PubMed Central

Zhang, Yingmei; Yuan, Ming; Bradley, Katherine M.; Dong, Feng; Anversa, Piero; Ren, Jun

2012-01-01

Obesity is often associated with reduced plasma IGF-1 levels, oxidative stress, mitochondrial damage and cardiac dysfunction. This study was designed to evaluate the impact of IGF-1 on high fat diet-induced oxidative, myocardial, geometric and mitochondrial responses. FVB and cardiomyocyte-specific IGF-1 overexpression transgenic mice were fed a low (10%) or high fat (45%) diet to induce obesity. High fat diet feeding led to glucose intolerance, elevated plasma levels of leptin, interleukin-6, insulin and triglyceride as well as reduced circulating IGF-1 levels. Echocardiography revealed reduced fractional shortening, increased end systolic and diastolic diameter, increased wall thickness, and cardiac hypertrophy in high fat-fed FVB mice. High fat diet promoted ROS generation, apoptosis, protein and mitochondrial damage, reduced ATP content, cardiomyocyte cross-sectional area, contractile and intracellular Ca2+ dysregulation, including depressed peak shortening and maximal velocity of shortening/relengthening, prolonged duration of relengthening, and dampened intracellular Ca2+ rise and clearance. Western blot analysis revealed disrupted phosphorylation of insulin receptor, post-receptor signaling molecules IRS-1 (tyrosine/serine phosphorylation), Akt, GSK3β, Foxo3a, mTOR, as well as downregulated expression of mitochondrial proteins PPARγ coactivator 1α (PGC1α) and UCP-2. Intriguingly, IGF-1 mitigated high fat diet feeding-induced alterations in ROS, protein and mitochondrial damage, ATP content, apoptosis, myocardial contraction, intracellular Ca2+ handling and insulin signaling, but not whole body glucose intolerance and cardiac hypertrophy. Exogenous IGF-1 treatment also alleviated high fat diet-induced cardiac dysfunction. Our data revealed that IGF-1 alleviates high fat diet-induced cardiac dysfunction despite persistent cardiac remodeling, possibly due to preserved cell survival, mitochondrial function and insulin signaling. PMID:22275536

Mitochondrial matrix metalloproteinase activation decreases myocyte contractility in hyperhomocysteinemia.

PubMed

Moshal, Karni S; Tipparaju, Srinivas M; Vacek, Thomas P; Kumar, Munish; Singh, Mahavir; Frank, Iluiana E; Patibandla, Phani K; Tyagi, Neetu; Rai, Jayesh; Metreveli, Naira; Rodriguez, Walter E; Tseng, Michael T; Tyagi, Suresh C

2008-08-01

Cardiomyocyte N-methyl-d-aspartate receptor-1 (NMDA-R1) activation induces mitochondrial dysfunction. Matrix metalloproteinase protease (MMP) induction is a negative regulator of mitochondrial function. Elevated levels of homocysteine [hyperhomocysteinemia (HHCY)] activate latent MMPs and causes myocardial contractile abnormalities. HHCY is associated with mitochondrial dysfunction. We tested the hypothesis that HHCY activates myocyte mitochondrial MMP (mtMMP), induces mitochondrial permeability transition (MPT), and causes contractile dysfunction by agonizing NMDA-R1. The C57BL/6J mice were administered homocystinemia (1.8 g/l) in drinking water to induce HHCY. NMDA-R1 expression was detected by Western blot and confocal microscopy. Localization of MMP-9 in the mitochondria was determined using confocal microscopy. Ultrastructural analysis of the isolated myocyte was determined by electron microscopy. Mitochondrial permeability was measured by a decrease in light absorbance at 540 nm using the spectrophotometer. The effect of MK-801 (NMDA-R1 inhibitor), GM-6001 (MMP inhibitor), and cyclosporine A (MPT inhibitor) on myocyte contractility and calcium transients was evaluated using the IonOptix video edge track detection system and fura 2-AM. Our results demonstrate that HHCY activated the mtMMP-9 and caused MPT by agonizing NMDA-R1. A significant decrease in percent cell shortening, maximal rate of contraction (-dL/dt), and maximal rate of relaxation (+dL/dt) was observed in HHCY. The decay of calcium transient amplitude was faster in the wild type compared with HHCY. Furthermore, the HHCY-induced decrease in percent cell shortening, -dL/dt, and +dL/dt was attenuated in the mice treated with MK-801, GM-6001, and cyclosporin A. We conclude that HHCY activates mtMMP-9 and induces MPT, leading to myocyte mechanical dysfunction by agonizing NMDA-R1.

Neuroprotective effects of lycopene in spinal cord injury in rats via antioxidative and anti-apoptotic pathway.

PubMed

Hu, Wei; Wang, Hongbo; Liu, Zhenfeng; Liu, Yanlu; Wang, Rong; Luo, Xiao; Huang, Yifei

2017-03-06

Oxidative damage induced-mitochondrial dysfunction and apoptosis has been widely studied in spinal cord injury (SCI). Lycopene, a polyunsaturated hydrocarbon, has the highest antioxidant capacity compared to the other carotenoids. However, the role of lycopene in SCI is unknown. In the present study, we evaluated the antioxidant effects of lycopene on mitochondrial dysfunction and apoptosis following T10 contusion SCI in rats. The rats were randomized into 5 groups: the sham group, the SCI group and the SCI pre-treated with lycopene (5, 10, or 20mg/kg) group. The SCI group showed increased malondialdehyde (MDA) content, decreased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) ability, which indicated that SCI could induce oxidative damage. What's more, the SCI group showed decreased mRNA expression of cytochrome b and mitochondrial transcription factor A (Tfam), and decreased mitochondrial membrane potential (ΔYm), which indicated that SCI could induce mitochondrial dysfunction. Besides, the SCI group showed decreased protein expression of bcl-2 and mitochondrial cytochrome C, increased protein expression of cytosolic cytochrome C, cleaved caspase-9, cleaved caspase-3 and bax, and increased TUNEL-positive cell numbers, which indicated that SCI could induce cell apoptosis. Fortunately, the lycopene treatment significantly ameliorated oxidative damage, mitochondrial dysfunction and cell apoptosis via the reversion of those parameters described above in the dose of lycopene of 10 and 20mg/kg. In addition, lycopene significantly ameliorated the hind limb motor disturbances in the SCI+lyco10 group and the SCI+lyco20 group compared with the SCI group. These results suggested that lycopene administration could improve total antioxidant status and might have neuroprotective effects on SCI. Copyright © 2017 Elsevier B.V. All rights reserved.

Disruption of mitochondrial function as mechanism for anti-cancer activity of a novel mitochondriotropic menadione derivative.

PubMed

Teixeira, José; Amorim, Ricardo; Santos, Katia; Soares, Pedro; Datta, Sandipan; Cortopassi, Gino A; Serafim, Teresa L; Sardão, Vilma A; Garrido, Jorge; Borges, Fernanda; Oliveira, Paulo J

2018-01-15

Menadione, also known as vitamin K 3 , is a 2-methyl-1,4 naphthoquinone with a potent cytotoxic activity mainly resulting from its quinone redox-cycling with production of reactive oxygen species (ROS). Although increased ROS generation is considered a relevant mechanism in cancer cell death, it may not be sufficiently effective to kill cancer cells due to phenotypic adaptations. Therefore, combining ROS-generating agents with other molecules targeting important cancer cell phenotypes can be an effective therapeutic strategy. As mitochondrial dysfunction has been implicated in many human diseases, including cancer, we describe here the discovery of a mitochondrial-directed agent (MitoK 3 ), which was developed by conjugating a TPP cation to the C3 position of the menadione's naphthoquinone ring, increasing its selective accumulation in mitochondria, as well as led to alterations of its redox properties and consequent biological outcome. MitoK 3 disturbed the mitochondrial bioenergetic apparatus, with subsequent loss of mitochondrial ATP production. The combinatory strategy of MitoK 3 with anticancer agent doxorubicin (DOX) resulted in a degree of cytotoxicity higher than those of the individual molecules, as the combination triggered tumour apoptotic cell death evident by caspase 3/9 activities, probably through mitochondrial destabilization or by interference with mitochondrial redox processes. The results of this investigation support the importance of drug discovery process in developing molecules that can be use as adjuvant therapy in patients with specific cancer subtypes. Copyright © 2017 Elsevier B.V. All rights reserved.

Neurometabolic mechanisms for memory enhancement and neuroprotection of methylene blue

PubMed Central

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

2011-01-01

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

The Role of Mitochondrial Dysfunction in Psychiatric Disease

ERIC Educational Resources Information Center

Scaglia, Fernando

2010-01-01

Mitochondrial respiratory chain disorders are a group of genetically and clinically heterogeneous disorders caused by the biochemical complexity of mitochondrial respiration and the fact that two genomes, one mitochondrial and one nuclear, encode the components of the respiratory chain. These disorders can manifest at birth or present later in…

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.

Cancer -- Pathological Breakdown of Coherent Energy States

NASA Astrophysics Data System (ADS)

Pokorný, Jiří Pokorný, Jan; Kobilková, Jitka; Jandová, Anna; Vrba, Jan; Vrba, Jan

The fundamental property of biological systems is a coherent state far from thermodynamic equilibrium excited and sustained by energy supply. Mitochondria in eukaryotic cells produce energy and form conditions for excitation of oscillations in microtubules. Microtubule polar oscillations generate a coherent state far from thermodynamic equilibrium which makes possible cooperation of cells in the tissue. Mitochondrial dysfunction (the Warburg effect) in cancer development breaks down energy of the coherent state far from thermodynamic equilibrium and excludes the afflicted cell from the ordered multicellular tissue system. Cancer lowering of energy and coherence of the state far from thermodynamic equilibrium is the biggest difference from the healthy cells. Cancer treatment should target mitochondrial dysfunction to restore the coherent state far from thermodynamic equilibrium, apoptotic pathway, and subordination of the cell in the tissue. A vast variety of genetic changes and other disturbances in different cancers can result in several triggers of mitochondrial dysfunction. In cancers with the Warburg effect, mitochondrial dysfunction can be treated by inhibition of four isoforms of pyruvate dehydrogenase kinases. Treatment of the reverse Warburg effect cancers would be more complicated. Disturbances of cellular electromagnetic activity by conducting and asbestos fibers present a special problem of treatment.

Antioxidants that protect mitochondria reduce interleukin-6 and oxidative stress, improve mitochondrial function, and reduce biochemical markers of organ dysfunction in a rat model of acute sepsis

PubMed Central

Lowes, D. A.; Webster, N. R.; Murphy, M. P.; Galley, H. F.

2013-01-01

Background Sepsis-induced organ failure is the major cause of death in critical care units, and is characterized by a massive dysregulated inflammatory response and oxidative stress. We investigated the effects of treatment with antioxidants that protect mitochondria (MitoQ, MitoE, or melatonin) in a rat model of lipopolysaccharide (LPS) plus peptidoglycan (PepG)-induced acute sepsis, characterized by inflammation, mitochondrial dysfunction and early organ damage. Methods Anaesthetized and ventilated rats received an i.v. bolus of LPS and PepG followed by an i.v. infusion of MitoQ, MitoE, melatonin, or saline for 5 h. Organs and blood were then removed for determination of mitochondrial and organ function, oxidative stress, and key cytokines. Results MitoQ, MitoE, or melatonin had broadly similar protective effects with improved mitochondrial respiration (P<0.002), reduced oxidative stress (P<0.02), and decreased interleukin-6 levels (P=0.0001). Compared with control rats, antioxidant-treated rats had lower levels of biochemical markers of organ dysfunction, including plasma alanine amino-transferase activity (P=0.02) and creatinine concentrations (P<0.0001). Conclusions Antioxidants that act preferentially in mitochondria reduce mitochondrial damage and organ dysfunction and decrease inflammatory responses in a rat model of acute sepsis. PMID:23381720

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

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

Cieri, Domenico; Brini, Marisa; Calì, Tito

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

Magnolol protects osteoblastic MC3T3-E1 cells against antimycin A-induced cytotoxicity through activation of mitochondrial function.

PubMed

Choi, Eun Mi

2012-06-01

Antimycin A treatment of cells blocks the mitochondrial electron transport chain and leads to elevated ROS generation. In the present study, we investigated the protective effects of magnolol, a hydroxylated biphenyl compound isolated from Magnolia officinalis, on antimycin A-induced toxicity in osteoblastic MC3T3-E1 cells. Osteoblastic MC3T3-E1 cells were pre-incubated with magnolol before treatment with antimycin A. Cell viability and mineralization of osteoblasts were assessed by MTT assay and Alizarin Red staining, respectively. Mitochondrial dysfunction in cells was measured by mitochondrial membrane potential (MMP), complex IV activity, and ATP level. The cellular antioxidant effect of magnolol in osteoblastic MC3T3-E1 cells was assessed by measuring cardiolipin oxidation, mitochondrial superoxide levels, and nitrotyrosine content. Phosphorylated cAMP-response element-binding protein (CREB ) was evaluated using ELISA assay. Pretreatment with magnolol prior to antimycin A exposure significantly reduced antimycin A-induced osteoblast dysfunction by preventing MMP dissipation, ATP loss, and CREB inactivation. Magnolol also reduced cardiolipin peroxidation, mitochondrial superoxide, and nitrotyrosine production induced by antimycin A. These results suggest that magnolol has a protective effect against antimycin A-induced cell damage by its antioxidant effects and the attenuation of mitochondrial dysfunction. All these data indicate that magnolol may reduce or prevent osteoblast degeneration in osteoporosis or other degenerative disorders.

Adipose tissue NAD+-homeostasis, sirtuins and poly(ADP-ribose) polymerases -important players in mitochondrial metabolism and metabolic health.

PubMed

Jokinen, Riikka; Pirnes-Karhu, Sini; Pietiläinen, Kirsi H; Pirinen, Eija

2017-08-01

Obesity, a chronic state of energy overload, is characterized by adipose tissue dysfunction that is considered to be the major driver for obesity associated metabolic complications. The reasons for adipose tissue dysfunction are incompletely understood, but one potential contributing factor is adipose tissue mitochondrial dysfunction. Derangements of adipose tissue mitochondrial biogenesis and pathways associate with obesity and metabolic diseases. Mitochondria are central organelles in energy metabolism through their role in energy derivation through catabolic oxidative reactions. The mitochondrial processes are dependent on the proper NAD + /NADH redox balance and NAD + is essential for reactions catalyzed by the key regulators of mitochondrial metabolism, sirtuins (SIRTs) and poly(ADP-ribose) polymerases (PARPs). Notably, obesity is associated with disturbed adipose tissue NAD + homeostasis and the balance of SIRT and PARP activities. In this review we aim to summarize existing literature on the maintenance of intracellular NAD + pools and the function of SIRTs and PARPs in adipose tissue during normal and obese conditions, with the purpose of comprehending their potential role in mitochondrial derangements and obesity associated metabolic complications. Understanding the molecular mechanisms that are the root cause of the adipose tissue mitochondrial derangements is crucial for developing new effective strategies to reverse obesity associated metabolic complications. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Review of the pathophysiological aspects involved in urological disease associated with metabolic syndrome.

PubMed

Sáenz Medina, J; Carballido Rodríguez, J

2016-06-01

Metabolic syndrome is a constellation of disorders that includes insulin resistance, central obesity, arterial hypertension and hyperlipidaemia. These disorders can have implications for the genitourinary apparatus. To conduct a review on the pathophysiological aspects that explain the relationship between metabolic syndrome and sexual dysfunction, lower urinary tract syndrome, prostate cancer and stone disease. We performed a qualitative, narrative literature review through a literature search on PubMed of articles published between 1997 and 2015, using the terms pathophysiology, metabolic syndrome, endothelial dysfunction, lipotoxicity, mitochondrial dysfunction, kidney stones, hypogonadism, erectile dysfunction, lower urinary tract syndrome and prostate cancer. Metabolic syndrome constitutes an established complex of symptoms, defined as the presence of insulin resistance, central obesity, hypertension and hyperlipidaemia. Endothelial dysfunction secondary to lipotoxicity generates an inflammatory state, which involves renal cell metabolism, vascularisation of the pelvis and androgen production. These facts explain the relationship between metabolic syndrome, nephrolithiasis, lower urinary tract syndrome, hypogonadism and erectile dysfunction in men. Strategies such as proper diet, regular exercise, insulin treatment, testosterone-replacement therapy, therapy with antioxidants and free-radical inhibitors and urological treatments classically used for lower urinary tract syndrome have shown promising results in this syndrome. Copyright © 2015 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

Mitochondria and mitochondrial DNA as relevant targets for environmental contaminants.

PubMed

Roubicek, Deborah A; Souza-Pinto, Nadja C de

2017-11-01

The mitochondrial DNA (mtDNA) is a closed circular molecule that encodes, in humans, 13 polypeptides components of the oxidative phosphorylation complexes. Integrity of the mitochondrial genome is essential for mitochondrial function and cellular homeostasis, and mutations and deletions in the mtDNA lead to oxidative stress, mitochondrial dysfunction and cell death. In vitro and in situ studies suggest that when exposed to certain genotoxins, mtDNA accumulates more damage than nuclear DNA, likely owing to its organization and localization in the mitochondrial matrix, which tends to accumulate lipophilic, positively charged molecules. In that regard, several relevant environmental and occupational contaminants have physical-chemical characteristics that indicate that they might accumulate in mitochondria and target mtDNA. Nonetheless, very little is known so far about mtDNA damage and mitochondrial dysfunction due to environmental exposure, either in model organisms or in humans. In this article, we discuss some of the characteristics of mtDNA which render it a potentially relevant target for damage by environmental contaminants, as well as possible functional consequences of damage/mutation accumulation. In addition, we review the data available in the literature focusing on mitochondrial effects of the most common classes of environmental pollutants. From that, we conclude that several lines of experimental evidence support the idea that mitochondria and mtDNA are susceptible and biologically relevant targets for pollutants, and more studies, including mechanistic ones, are needed to shed more light into the contribution of mitochondrial dysfunction to the environmental and human health effects of chemical exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

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 Function in Allergic Disease.

PubMed

Iyer, Divyaanka; Mishra, Navya; Agrawal, Anurag

2017-05-01

The connections between allergy, asthma and metabolic syndrome are becoming increasingly clear. Recent research suggests a unifying mitochondrial link between the diverse phenotypes of these interlinked morbidities. The scope of this review is to highlight cellular mechanisms, epidemiology and environmental allergens influencing mitochondrial function and its importance in allergy and asthma. We briefly also consider the potential of mitochondria-targeted therapies in prevention and cure. Recent research has shown allergy, asthma and metabolic syndrome to be linked to mitochondrial dysfunction. Environmental pollutants and allergens are observed to cause mitochondrial dysfunction, primarily by inducing oxidative stress and ROS production. Malfunctioning mitochondria change the bioenergetics of the cell and its metabolic profile to favour systemic inflammation, which drives all three types of morbidities. Given the existing experimental evidence, approaches targeting mitochondria (e.g. antioxidant therapy and mitochondrial replacement) are being conducted in relevant disease models-with some progressing towards clinical trials, making mitochondrial function the focus of translational therapy research in asthma, allergy and linked metabolic syndrome.

Triptolide-induced mitochondrial damage dysregulates fatty acid metabolism in mouse sertoli cells.

PubMed

Cheng, Yisen; Chen, Gaojian; Wang, Li; Kong, Jiamin; Pan, Ji; Xi, Yue; Shen, Feihai; Huang, Zhiying

2018-08-01

Triptolide is a major active ingredient of tripterygium glycosides, used for the therapy of immune and inflammatory diseases. However, its clinical applications are limited by severe male fertility toxicity associated with decreased sperm count, mobility and testicular injures. In this study, we determined that triptoide-induced mitochondrial dysfunction triggered reduction of lactate and dysregulation of fatty acid metabolism in mouse Sertoli cells. First, triptolide induced mitochondrial damage through the suppressing of proliferator-activated receptor coactivator-1 alpha (PGC-1α) activity and protein. Second, mitochondrial damage decreased lactate production and dysregulated fatty acid metabolism. Finally, mitochondrial dysfunction was initiated by the inhibition of sirtuin 1 (SIRT1) with the regulation of AMP-activated protein kinase (AMPK) in Sertoli cells after triptolide treatment. Meanwhile, triptolide induced mitochondrial fatty acid oxidation dysregulation by increasing AMPK phosphorylation. Taken together, we provide evidence that the mechanism of triptolide-induced testicular toxicity under mitochondrial injury may involve a metabolic change. Copyright © 2018 Elsevier B.V. All rights reserved.

Early Effects of Prolonged Cardiac Arrest and Ischemic Postconditioning during Cardiopulmonary Resuscitation on Cardiac and Brain Mitochondrial Function in Pigs.

PubMed

Matsuura, Timothy R; Bartos, Jason A; Tsangaris, Adamantios; Shekar, Kadambari Chandra; Olson, Matthew D; Riess, Matthias L; Bienengraeber, Martin; Aufderheide, Tom P; Neumar, Robert W; Rees, Jennifer N; McKnite, Scott H; Dikalova, Anna E; Dikalov, Sergey I; Douglas, Hunter F; Yannopoulos, Demetris

2017-07-01

Out-of-hospital cardiac arrest (CA) is a prevalent medical crisis resulting in severe injury to the heart and brain and an overall survival of less than 10%. Mitochondrial dysfunction is predicted to be a key determinant of poor outcomes following prolonged CA. However, the onset and severity of mitochondrial dysfunction during CA and cardiopulmonary resuscitation (CPR) is not fully understood. Ischemic postconditioning (IPC), controlled pauses during the initiation of CPR, has been shown to improve cardiac function and neurologically favorable outcomes after 15min of CA. We tested the hypothesis that mitochondrial dysfunction develops during prolonged CA and can be rescued with IPC during CPR (IPC-CPR). A total of 63 swine were randomized to no ischemia (Naïve), 19min of ventricular fibrillation (VF) CA without CPR (Untreated VF), or 15min of CA with 4min of reperfusion with either standard CPR (S-CPR) or IPC-CPR. Mitochondria were isolated from the heart and brain to quantify respiration, rate of ATP synthesis, and calcium retention capacity (CRC). Reactive oxygen species (ROS) production was quantified from fresh frozen heart and brain tissue. Compared to Naïve, Untreated VF induced cardiac and brain ROS overproduction concurrent with decreased mitochondrial respiratory coupling and CRC, as well as decreased cardiac ATP synthesis. Compared to Untreated VF, S-CPR attenuated brain ROS overproduction but had no other effect on mitochondrial function in the heart or brain. Compared to Untreated VF, IPC-CPR improved cardiac mitochondrial respiratory coupling and rate of ATP synthesis, and decreased ROS overproduction in the heart and brain. Fifteen minutes of VF CA results in diminished mitochondrial respiration, ATP synthesis, CRC, and increased ROS production in the heart and brain. IPC-CPR attenuates cardiac mitochondrial dysfunction caused by prolonged VF CA after only 4min of reperfusion, suggesting that IPC-CPR is an effective intervention to reduce cardiac injury. However, reperfusion with both CPR methods had limited effect on mitochondrial function in the brain, emphasizing an important physiological divergence in post-arrest recovery between those two vital organs. Copyright © 2017 Elsevier B.V. All rights reserved.

Cardiovascular Mitochondrial Dysfunction Induced by Cocaine: Biomarkers and Possible Beneficial Effects of Modulators of Oxidative Stress.

PubMed

Graziani, Manuela; Sarti, Paolo; Arese, Marzia; Magnifico, Maria Chiara; Badiani, Aldo; Saso, Luciano

2017-01-01

Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies.

Mitochondrial dysfunction and cellular metabolic deficiency in Alzheimer's disease.

PubMed

Gu, Xue-Mei; Huang, Han-Chang; Jiang, Zhao-Feng

2012-10-01

Alzheimer's disease (AD) is an age-related neurodegenerative disorder. The pathology of AD includes amyloid-β (Aβ) deposits in neuritic plaques and neurofibrillary tangles composed of hyperphosphorylated tau, as well as neuronal loss in specific brain regions. Increasing epidemiological and functional neuroimaging evidence indicates that global and regional disruptions in brain metabolism are involved in the pathogenesis of this disease. Aβ precursor protein is cleaved to produce both extracellular and intracellular Aβ, accumulation of which might interfere with the homeostasis of cellular metabolism. Mitochondria are highly dynamic organelles that not only supply the main energy to the cell but also regulate apoptosis. Mitochondrial dysfunction might contribute to Aβ neurotoxicity. In this review, we summarize the pathways of Aβ generation and its potential neurotoxic effects on cellular metabolism and mitochondrial dysfunction.

Hydrogen peroxide production is not primarily increased in human myotubes established from type 2 diabetic subjects.

PubMed

Minet, A D; Gaster, M

2011-09-01

Increased oxidative stress and mitochondrial dysfunction have been implicated in the development of insulin resistance in type 2 diabetes. To date, it is unknown whether increased mitochondrial reactive oxygen species (ROS) production in skeletal muscle from patients with type 2 diabetes is primarily increased or a secondary adaptation to environmental, lifestyle, and hormonal factors. This study investigates whether ROS production is primarily increased in isolated diabetic myotubes. Mitochondrial membrane potential, hydrogen peroxide (H(2)O(2)), superoxide, and mitochondrial mass were determined in human myotubes precultured under normophysiological conditions. Furthermore, the corresponding ATP synthesis was measured in isolated mitochondria. Muscle biopsies were taken from 10 lean subjects, 10 obese subjects, and 10 subjects with type 2 diabetes; satellite cells were isolated, cultured, and differentiated to myotubes. Mitochondrial mass, membrane potential/mitochondrial mass, and superoxide-production/mitochondrial mass were not different between groups. In contrast, H(2)O(2) production/mitochondrial mass and ATP production were significantly reduced in diabetic myotubes compared to lean controls (P < 0.05). The ATP/H(2)O(2) ratios were not significantly different between groups. Our result indicates that the ROS production is not primarily increased in diabetic myotubes but rather is reduced. Moreover, the comparable ATP/H(2)O(2) ratios indicate that the reduced ROS production in diabetic myotubes parallels the reduced ATP production because ROS production in diabetic myotubes must be considered to be in a proportion comparable to lean. Thus, the increased ROS production seen in skeletal muscle of type 2 diabetic patients is an adaptation to the in vivo conditions.

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-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.

Increased mitochondrial calcium sensitivity and abnormal expression of innate immunity genes precede dopaminergic defects in Pink1-deficient mice.

PubMed

Akundi, Ravi S; Huang, Zhenyu; Eason, Joshua; Pandya, Jignesh D; Zhi, Lianteng; Cass, Wayne A; Sullivan, Patrick G; Büeler, Hansruedi

2011-01-13

PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca²+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1⁻/⁻ mice. Purified brain mitochondria of Pink1⁻/⁻ mice showed impaired Ca²+ storage capacity, resulting in increased Ca²+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1⁻/⁻ mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1⁻/⁻ mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1⁻/⁻ mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1⁻/⁻ embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1⁻/⁻ mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting. Increased mitochondrial Ca²+ sensitivity and JNK activity are early defects in Pink1⁻/⁻ mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1⁻/⁻ mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-κB activation may predispose neurons of Pink1⁻/⁻ mice to inflammation and injury-induced cell death.

MitoTEMPO Prevents Oxalate Induced Injury in NRK-52E Cells via Inhibiting Mitochondrial Dysfunction and Modulating Oxidative Stress

PubMed Central

Yu, Xiao; Liu, Jihong

2017-01-01

As one of the major risks for urolithiasis, hyperoxaluria can be caused by genetic defect or dietary intake. And high oxalate induced renal epithelial cells injury is related to oxidative stress and mitochondrial dysfunction. Here, we investigated whether MitoTEMPO, a mitochondria-targeted antioxidant, could protect against oxalate mediated injury in NRK-52E cells via inhibiting mitochondrial dysfunction and modulating oxidative stress. MitoSOX Red was used to determine mitochondrial ROS (mtROS) production. Mitochondrial membrane potential (Δψm) and quantification of ATP synthesis were measured to evaluate mitochondrial function. The protein expression of Nox4, Nox2, and p22 was also detected to explore the effect of oxalate and MitoTEMPO on NADPH oxidase. Our results revealed that pretreatment with MitoTEMPO significantly inhibited oxalate induced lactate dehydrogenase (LDH) and malondialdehyde (MDA) release and decreased oxalate induced mtROS generation. Further, MitoTEMPO pretreatment restored disruption of Δψm and decreased ATP synthesis mediated by oxalate. In addition, MitoTEMPO altered the protein expression of Nox4 and p22 and decreased the protein expression of IL-6 and osteopontin (OPN) induced by oxalate. We concluded that MitoTEMPO may be a new candidate to protect against oxalate induced kidney injury as well as urolithiasis. PMID:28116040

Endothelial mitochondrial oxidative stress determines podocyte depletion in segmental glomerulosclerosis

PubMed Central

Daehn, Ilse; Casalena, Gabriella; Zhang, Taoran; Shi, Shaolin; Fenninger, Franz; Barasch, Nicholas; Yu, Liping; D’Agati, Vivette; Schlondorff, Detlef; Kriz, Wilhelm; Haraldsson, Borje; Bottinger, Erwin P.

2014-01-01

Focal segmental glomerular sclerosis (FSGS) is a primary kidney disease that is commonly associated with proteinuria and progressive loss of glomerular function, leading to development of chronic kidney disease (CKD). FSGS is characterized by podocyte injury and depletion and collapse of glomerular capillary segments. Progression of FSGS is associated with TGF-β activation in podocytes; however, it is not clear how TGF-β signaling promotes disease. Here, we determined that podocyte-specific activation of TGF-β signaling in transgenic mice and BALB/c mice with Adriamycin-induced glomerulosclerosis is associated with endothelin-1 (EDN1) release by podocytes, which mediates mitochondrial oxidative stress and dysfunction in adjacent endothelial cells via paracrine EDN1 receptor type A (EDNRA) activation. Endothelial dysfunction promoted podocyte apoptosis, and inhibition of EDNRA or scavenging of mitochondrial-targeted ROS prevented podocyte loss, albuminuria, glomerulosclerosis, and renal failure. We confirmed reciprocal crosstalk between podocytes and endothelial cells in a coculture system. Biopsies from patients with FSGS exhibited increased mitochondrial DNA damage, consistent with EDNRA-mediated glomerular endothelial mitochondrial oxidative stress. Our studies indicate that segmental glomerulosclerosis develops as a result of podocyte-endothelial crosstalk mediated by EDN1/EDNRA-dependent mitochondrial dysfunction and suggest that targeting the reciprocal interaction between podocytes and endothelia may provide opportunities for therapeutic intervention in FSGS. PMID:24590287

Coenzyme Q{sub 10} and alpha-tocopherol protect against amitriptyline toxicity

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

Cordero, Mario D.; Dpto. Citologia e Histologia Normal y Patologica, Facultad de Medicina. Universidad de Sevilla. 41009 Sevilla; Moreno-Fernandez, Ana Maria

Since amitriptyline is a very frequently prescribed antidepressant drug, it is not surprising that amitriptyline toxicity is relatively common. Amitriptyline toxic systemic effects include cardiovascular, autonomous nervous, and central nervous systems. To understand the mechanisms of amitriptyline toxicity we studied the cytotoxic effects of amitriptyline treatment on cultured primary human fibroblasts and zebrafish embryos, and the protective role of coenzyme Q{sub 10} and alpha-tocopherol, two membrane antioxidants. We found that amitriptyline treatment induced oxidative stress and mitochondrial dysfunction in primary human fibroblasts. Mitochondrial dysfunction in amitriptyline treatment was characterized by reduced expression levels of mitochondrial proteins and coenzyme Q{sub 10},more » decreased NADH:cytochrome c reductase activity, and a drop in mitochondrial membrane potential. Moreover, and as a consequence of these toxic effects, amitriptyline treatment induced a significant increase in apoptotic cell death activating mitochondrial permeability transition. Coenzyme Q{sub 10} and alpha-tocopherol supplementation attenuated ROS production, lipid peroxidation, mitochondrial dysfunction, and cell death, suggesting that oxidative stress affecting cell membrane components is involved in amitriptyline cytotoxicity. Furthermore, amitriptyline-dependent toxicity and antioxidant protection were also evaluated in zebrafish embryos, a well established vertebrate model to study developmental toxicity. Amitriptyline significantly increased embryonic cell death and apoptosis rate, and both antioxidants provided a significant protection against amitriptyline embryotoxicity.« less

Adipocyte Fatty Acid-Binding Protein Promotes Palmitate-Induced Mitochondrial Dysfunction and Apoptosis in Macrophages

PubMed Central

Li, Hui; Xiao, Yang; Tang, Lin; Zhong, Feng; Huang, Gan; Xu, Jun-Mei; Xu, Ai-Min; Dai, Ru-Ping; Zhou, Zhi-Guang

2018-01-01

A high level of circulating free fatty acids (FFAs) is known to be an important trigger for macrophage apoptosis during the development of atherosclerosis. However, the underlying mechanism by which FFAs result in macrophage apoptosis is not well understood. In cultured human macrophage Thp-1 cells, we showed that palmitate (PA), the most abundant FFA in circulation, induced excessive reactive oxidative substance production, increased malondialdehyde concentration, and decreased adenosine triphosphate levels. Furthermore, PA treatment also led to mitochondrial dysfunction, including the decrease of mitochondrial number, the impairment of respiratory complex IV and succinate dehydrogenase activity, and the reduction of mitochondrial membrane potential. Mitochondrial apoptosis was also detected after PA treatment, indicated by a decrease in cytochrome c release, downregulation of Bcl-2, upregulation of Bax, and increased caspase-3 activity. PA treatment upregulated the expression of adipocyte fatty acid-binding protein (A-FABP), a critical regulator of fatty acid trafficking and lipid metabolism. Inhibition of A-FABP with BMS309403, a small-molecule A-FABP inhibitor, almost reversed all of these indexes. Thus, this study suggested that PA-mediated macrophage apoptosis through A-FABP upregulation, which subsequently resulted in mitochondrial dysfunction and reactive oxidative stress. Inhibition of A-FABP may be a potential therapeutic target for macrophage apoptosis and to delay the progress of atherosclerosis. PMID:29441065

Stabilization of mitochondrial membrane potential prevents doxorubicin-induced cardiotoxicity in isolated rat heart

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

Montaigne, David; Marechal, Xavier; Baccouch, Riadh

2010-05-01

The present study was undertaken to examine the effects of doxorubicin on left ventricular function and cellular energy state in intact isolated hearts, and, to test whether inhibition of mitochondrial membrane potential dissipation would prevent doxorubicin-induced mitochondrial and myocardial dysfunction. Myocardial contractile performance and mitochondrial respiration were evaluated by left ventricular tension and its first derivatives and cardiac fiber respirometry, respectively. NADH levels, mitochondrial membrane potential and glucose uptake were monitored non-invasively via epicardial imaging of the left ventricular wall of Langendorff-perfused rat hearts. Heart performance was reduced in a time-dependent manner in isolated rat hearts perfused with Krebs-Henseleit solutionmore » containing 1 muM doxorubicin. Compared with controls, doxorubicin induced acute myocardial dysfunction (dF/dt{sub max} of 105 +- 8 mN/s in control hearts vs. 49 +- 7 mN/s in doxorubicin-treated hearts; *p < 0.05). In cardiac fibers prepared from perfused hearts, doxorubicin induced depression of mitochondrial respiration (respiratory control ratio of 4.0 +- 0.2 in control hearts vs. 2.2 +- 0.2 in doxorubicin-treated hearts; *p < 0.05) and cytochrome c oxidase kinetic activity (24 +- 1 muM cytochrome c/min/mg in control hearts vs. 14 +- 3 muM cytochrome c/min/mg in doxorubicin-treated hearts; *p < 0.05). Acute cardiotoxicity induced by doxorubicin was accompanied by NADH redox state, mitochondrial membrane potential, and glucose uptake reduction. Inhibition of mitochondrial permeability transition pore opening by cyclosporine A largely prevented mitochondrial membrane potential dissipation, cardiac energy state and dysfunction. These results suggest that in intact hearts an impairment of mitochondrial metabolism is involved in the development of doxorubicin cardiotoxicity.« less

Tetrahydrocurcumin ameliorates homocysteine-mediated mitochondrial remodeling in brain endothelial cells.

PubMed

Vacek, Jonathan C; Behera, Jyotirmaya; George, Akash K; Kamat, Pradip K; Kalani, Anuradha; Tyagi, Neetu

2018-04-01

Homocysteine (Hcy) causes endothelial dysfunction by inducing oxidative stress in most neurodegenerative disorders. This dysfunction is highly correlated with mitochondrial dynamics such as fusion and fission. However, there are no strategies to prevent Hcy-induced mitochondrial remodeling. Tetrahydrocurcumin (THC) is an anti-inflammatory and anti-oxidant compound. We hypothesized that THC may ameliorates Hcy-induced mitochondria remodeling in mouse brain endothelial cells (bEnd3) cells. bEnd3 cells were exposed to Hcy treatment in the presence or absence of THC. Cell viability and autophagic cell death were measured with MTT and MDC staining assay. Reactive oxygen species (ROS) production was determined using DCFH-DA staining by confocal microscopy. Autophagy flux was assessed using a conventional GFP-microtubule-associated protein 1 light chain 3 (LC3) dot assay. Interaction of phagophore marker LC-3 with mitochondrial receptor NIX was observed by confocal imaging. Mitochondrial fusion and fission were evaluated by western blot and RT-PCR. Our results demonstrated that Hcy resulted in cell toxicity in a dose-dependent manner and supplementation of THC prevented the detrimental effects of Hcy on cell survival. Furthermore, Hcy also upregulated fission marker (DRP-1), fusion marker (Mfn2), and autophagy marker (LC-3). Finally, we observed that Hcy activated mitochondrial specific phagophore marker (LC-3) and co-localized with the mitochondrial receptor NIX, as viewed by confocal microscopy. Pretreatment of bEnd3 with THC (15 μM) ameliorated Hcy-induced oxidative damage, mitochondrial fission/fusion, and mitophagy. Our studies strongly suggest that THC has beneficial effects on mitochondrial remodeling and could be developed as a potential therapeutic agent against hyperhomocysteinemia (HHcy) induced mitochondrial dysfunction. © 2017 Wiley Periodicals, Inc.

Garlic activates SIRT-3 to prevent cardiac oxidative stress and mitochondrial dysfunction in diabetes.

PubMed

Sultana, Md Razia; Bagul, Pankaj K; Katare, Parameshwar B; Anwar Mohammed, Soheb; Padiya, Raju; Banerjee, Sanjay K

2016-11-01

Cardiac complications are major contributor in the mortality of diabetic people. Mitochondrial dysfunctioning is a crucial contributor for the cardiac complications in diabetes, and SIRT-3 remains the major mitochondrial deacetylase. We hypothesized whether garlic has any role on SIRT-3 to prevent mitochondrial dysfunction in diabetic heart. Rats with developed hyperglycemia after STZ injection were divided into two groups; diabetic (Dia) and diabetic+garlic (Dia+Garl). Garlic was administered at a dose of 250mg/kg/day, orally for four weeks. An additional group was maintained to evaluate the effect of raw garlic administration on control rat heart. We have observed altered functioning of cardiac mitochondrial enzymes involved in metabolic pathways, and increased levels of cardiac ROS with decreased activity of catalase and SOD in diabetic rats. Cardiac mRNA expression of TFAM, PGC-1α, and CO1 was also altered in diabetes. In addition, reduced levels of electron transport chain complexes that observed in Dia group were normalized with garlic administration. This indicates the presence of increased oxidative stress with mitochondrial dysfunctioning in diabetic heart. We have observed reduced activity of SIRT3 and increased acetylation of MnSOD. Silencing SIRT-3 in cells also revealed the same. However, administration of garlic improved the SIRT-3 and MnSOD activity, by deacetylating MnSOD. Increased SOD activity was correlated with reduced levels of ROS in garlic-administered rat hearts. Collectively, our results provide an insight into garlic's protection to T1DM heart through activation of SIRT3-MnSOD pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed

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

2014-08-01

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

MELAS syndrome and cardiomyopathy: linking mitochondrial function to heart failure pathogenesis.

PubMed

Hsu, Ying-Han R; Yogasundaram, Haran; Parajuli, Nirmal; Valtuille, Lucas; Sergi, Consolato; Oudit, Gavin Y

2016-01-01

Heart failure remains an important clinical burden, and mitochondrial dysfunction plays a key role in its pathogenesis. The heart has a high metabolic demand, and mitochondrial function is a key determinant of myocardial performance. In mitochondrial disorders, hypertrophic remodeling is the early pattern of cardiomyopathy with progression to dilated cardiomyopathy, conduction defects and ventricular pre-excitation occurring in a significant proportion of patients. Cardiac dysfunction occurs in approximately a third of patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, a stereotypical example of a mitochondrial disorder leading to a cardiomyopathy. We performed unique comparative ultrastructural and gene expression in a MELAS heart compared with non-failing controls. Our results showed a remarkable increase in mitochondrial inclusions and increased abnormal mitochondria in MELAS cardiomyopathy coupled with variable sarcomere thickening, heterogeneous distribution of affected cardiomyocytes and a greater elevation in the expression of disease markers. Investigation and management of patients with mitochondrial cardiomyopathy should follow the well-described contemporary heart failure clinical practice guidelines and include an important role of medical and device therapies. Directed metabolic therapy is lacking, but current research strategies are dedicated toward improving mitochondrial function in patients with mitochondrial disorders.

Pathologic and Therapeutic Implications for the Cell Biology of Parkin

PubMed Central

Charan, Rakshita A.; LaVoie, Matthew J.

2015-01-01

Mutations in the E3 ligase parkin are the most common cause of autosomal recessive Parkinson's disease (PD), but it is believed that parkin dysfunction may also contribute to idiopathic PD. Since its discovery, parkin has been implicated in supporting multiple neuroprotective pathways, many revolving around the maintenance of mitochondrial health quality control and governance of cell survival. Recent advances across the structure, biochemistry, and cell biology of parkin have provided great insights into the etiology of parkin-linked and idiopathic PD and may ultimately generate novel therapeutic strategies to slow or halt disease progression. This review describes the various pathways in which parkin acts and the mechanisms by which parkin may be targeted for therapeutic intervention. PMID:25697646

Dissecting Long-Term Glucose Metabolism Identifies New Susceptibility Period for Metabolic Dysfunction in Aged Mice

PubMed Central

Koch, Franziska; Ibrahim, Saleh M.; Vera, Julio; Wolkenhauer, Olaf; Tiedge, Markus

2015-01-01

Metabolic disorders, like diabetes and obesity, are pathogenic outcomes of imbalance in glucose metabolism. Nutrient excess and mitochondrial imbalance are implicated in dysfunctional glucose metabolism with age. We used conplastic mouse strains with defined mitochondrial DNA (mtDNA) mutations on a common nuclear genomic background, and administered a high-fat diet up to 18 months of age. The conplastic mouse strain B6-mtFVB, with a mutation in the mt-Atp8 gene, conferred β-cell dysfunction and impaired glucose tolerance after high-fat diet. To our surprise, despite of this functional deficit, blood glucose levels adapted to perturbations with age. Blood glucose levels were particularly sensitive to perturbations at the early age of 3 to 6 months. Overall the dynamics consisted of a peak between 3–6 months followed by adaptation by 12 months of age. With the help of mathematical modeling we delineate how body weight, insulin and leptin regulate this non-linear blood glucose dynamics. The model predicted a second rise in glucose between 15 and 21 months, which could be experimentally confirmed as a secondary peak. We therefore hypothesize that these two peaks correspond to two sensitive periods of life, where perturbations to the basal metabolism can mark the system for vulnerability to pathologies at later age. Further mathematical modeling may perspectively allow the design of targeted periods for therapeutic interventions and could predict effects on weight loss and insulin levels under conditions of pre-diabetic obesity. PMID:26540285

CLUH couples mitochondrial distribution to the energetic and metabolic status.

PubMed

Wakim, Jamal; Goudenege, David; Perrot, Rodolphe; Gueguen, Naig; Desquiret-Dumas, Valerie; Chao de la Barca, Juan Manuel; Dalla Rosa, Ilaria; Manero, Florence; Le Mao, Morgane; Chupin, Stephanie; Chevrollier, Arnaud; Procaccio, Vincent; Bonneau, Dominique; Logan, David C; Reynier, Pascal; Lenaers, Guy; Khiati, Salim

2017-06-01

Mitochondrial dynamics and distribution are critical for supplying ATP in response to energy demand. CLUH is a protein involved in mitochondrial distribution whose dysfunction leads to mitochondrial clustering, the metabolic consequences of which remain unknown. To gain insight into the role of CLUH on mitochondrial energy production and cellular metabolism, we have generated CLUH-knockout cells using CRISPR/Cas9. Mitochondrial clustering was associated with a smaller cell size and with decreased abundance of respiratory complexes, resulting in oxidative phosphorylation (OXPHOS) defects. This energetic impairment was found to be due to the alteration of mitochondrial translation and to a metabolic shift towards glucose dependency. Metabolomic profiling by mass spectroscopy revealed an increase in the concentration of some amino acids, indicating a dysfunctional Krebs cycle, and increased palmitoylcarnitine concentration, indicating an alteration of fatty acid oxidation, and a dramatic decrease in the concentrations of phosphatidylcholine and sphingomyeline, consistent with the decreased cell size. Taken together, our study establishes a clear function for CLUH in coupling mitochondrial distribution to the control of cell energetic and metabolic status. © 2017. Published by The Company of Biologists Ltd.

Mitochondria-targeted antioxidant mitotempo protects mitochondrial function against amyloid beta toxicity in primary cultured mouse neurons.

PubMed

Hu, Hongtao; Li, Mo

2016-09-09

Mitochondrial defects including excess reactive oxygen species (ROS) production and compromised ATP generation are featured pathology in Alzheimer's disease (AD). Amyloid beta (Aβ)-mediated mitochondrial ROS overproduction disrupts intra-neuronal Redox balance, in turn exacerbating mitochondrial dysfunction leading to neuronal injury. Previous studies have found the beneficial effects of mitochondria-targeted antioxidants in preventing mitochondrial dysfunction and neuronal injury in AD animal and cell models, suggesting that mitochondrial ROS scavengers hold promise for the treatment of this neurological disorder. In this study, we have determined that mitotempo, a novel mitochondria-targeted antioxidant protects mitochondrial function from the toxicity of Aβ in primary cultured neurons. Our results showed that Aβ-promoted mitochondrial superoxide production and neuronal lipid oxidation were significantly suppressed by the application of mitotempo. Moreover, mitotempo also demonstrated protective effects on mitochondrial bioenergetics evidenced by preserved mitochondrial membrane potential, cytochrome c oxidase activity as well as ATP production. In addition, the Aβ-induced mitochondrial DNA (mtDNA) depletion and decreased expression levels of mtDNA replication-related DNA polymerase gamma (DNA pol γ) and Twinkle were substantially mitigated by mitotempo. Therefore, our study suggests that elimination of excess mitochondrial ROS rescues mitochondrial function in Aβ-insulted neruons; and mitotempo has the potential to be a promising therapeutic agent to protect mitochondrial and neuronal function in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

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

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

Tan, Jun; Song, Meijun; Zhou, Mi

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

Diminished superoxide generation is associated with respiratory chain dysfunction and changes in the mitochondrial proteome of sensory neurons from diabetic rats.

PubMed

Akude, Eli; Zherebitskaya, Elena; Chowdhury, Subir K Roy; Smith, Darrell R; Dobrowsky, Rick T; Fernyhough, Paul

2011-01-01

Impairments in mitochondrial function have been proposed to play a role in the etiology of diabetic sensory neuropathy. We tested the hypothesis that mitochondrial dysfunction in axons of sensory neurons in type 1 diabetes is due to abnormal activity of the respiratory chain and an altered mitochondrial proteome. Proteomic analysis using stable isotope labeling with amino acids in cell culture (SILAC) determined expression of proteins in mitochondria from dorsal root ganglia (DRG) of control, 22-week-old streptozotocin (STZ)-diabetic rats, and diabetic rats treated with insulin. Rates of oxygen consumption and complex activities in mitochondria from DRG were measured. Fluorescence imaging of axons of cultured sensory neurons determined the effect of diabetes on mitochondrial polarization status, oxidative stress, and mitochondrial matrix-specific reactive oxygen species (ROS). Proteins associated with mitochondrial dysfunction, oxidative phosphorylation, ubiquinone biosynthesis, and the citric acid cycle were downregulated in diabetic samples. For example, cytochrome c oxidase subunit IV (COX IV; a complex IV protein) and NADH dehydrogenase Fe-S protein 3 (NDUFS3; a complex I protein) were reduced by 29 and 36% (P < 0.05), respectively, in diabetes and confirmed previous Western blot studies. Respiration and mitochondrial complex activity was significantly decreased by 15 to 32% compared with control. The axons of diabetic neurons exhibited oxidative stress and depolarized mitochondria, an aberrant adaption to oligomycin-induced mitochondrial membrane hyperpolarization, but reduced levels of intramitochondrial superoxide compared with control. Abnormal mitochondrial function correlated with a downregulation of mitochondrial proteins, with components of the respiratory chain targeted in lumbar DRG in diabetes. The reduced activity of the respiratory chain was associated with diminished superoxide generation within the mitochondrial matrix and did not contribute to oxidative stress in axons of diabetic neurons. Alternative pathways involving polyol pathway activity appear to contribute to raised ROS in axons of diabetic neurons under high glucose concentration.

Desensitizing Mitochondrial Permeability Transition by ERK-Cyclophilin D Axis Contributes to the Neuroprotective Effect of Gallic Acid against Cerebral Ischemia/Reperfusion Injury

PubMed Central

Sun, Jing; Ren, Da-Dui; Wan, Jin-Yi; Chen, Chen; Chen, Dong; Yang, Huan; Feng, Chun-Lai; Gao, Jing

2017-01-01

Ischemic stroke is a devastating disease with complex pathophysiology. Much evidence confirms that opening of the mitochondrial permeability transition pore (MPTP) is related with mitochondrial dysfunction to apoptosis in ischemic stroke, thus elucidating its signaling mechanism and screening novel MPTP inhibitor is therefore of paramount importance. Our earlier studies identified that gallic acid (GA), a naturally occurring plant phenol, endows with effect on inhibition of mitochondrial dysfunction, which has significant neuroprotective effect in cerebral ischemia/reperfusion injury. However, its molecular mechanisms regulating mitochondrial dysfunction remain elusive. Here, we uncover a role of GA in protecting mitochondria via MPTP inhibition. In addition to inhibit CypD binding to adenine nucleotide translocator, GA potentiates extracellular signal-regulated kinases (ERK) phosphorylation, leading to a decrease in cyclophilin D (CypD) expression, resulting in a desensitization to induction of MPTP, thus inhibiting caspase activation and ultimately giving rise to cellular survival. Our study firstly identifies ERK-CypD axis is one of the cornerstones of the cell death pathways following ischemic stroke, and confirms GA is a novel inhibitor of MPTP, which inhibits apoptosis depending on regulating the ERK-CypD axis. PMID:28428752

Acute high-altitude hypoxic brain injury: Identification of ten differential proteins

PubMed Central

Li, Jianyu; Qi, Yuting; Liu, Hui; Cui, Ying; Zhang, Li; Gong, Haiying; Li, Yaxiao; Li, Lingzhi; Zhang, Yongliang

2013-01-01

Hypobaric hypoxia can cause severe brain damage and mitochondrial dysfunction, and is involved in hypoxic brain injury. However, little is currently known about the mechanisms responsible for mitochondrial dysfunction in hypobaric hypoxic brain damage. In this study, a rat model of hypobaric hypoxic brain injury was established to investigate the molecular mechanisms associated with mitochondrial dysfunction. As revealed by two-dimensional electrophoresis analysis, 16, 21, and 36 differential protein spots in cerebral mitochondria were observed at 6, 12, and 24 hours post-hypobaric hypoxia, respectively. Furthermore, ten protein spots selected from each hypobaric hypoxia subgroup were similarly regulated and were identified by mass spectrometry. These detected proteins included dihydropyrimidinase-related protein 2, creatine kinase B-type, isovaleryl-CoA dehydrogenase, elongation factor Ts, ATP synthase beta-subunit, 3-mercaptopyruvate sulfurtransferase, electron transfer flavoprotein alpha-subunit, Chain A of 2-enoyl-CoA hydratase, NADH dehydrogenase iron-sulfur protein 8 and tropomyosin beta chain. These ten proteins are all involved in the electron transport chain and the function of ATP synthase. Our findings indicate that hypobaric hypoxia can induce the differential expression of several cerebral mitochondrial proteins, which are involved in the regulation of mitochondrial energy production. PMID:25206614

Reactive Oxygen Species, Mitochondria, and Endothelial Cell Death during In Vitro Simulated Dives.

PubMed

Wang, Qiong; Guerrero, François; Mazur, Aleksandra; Lambrechts, Kate; Buzzacott, Peter; Belhomme, Marac; Theron, Michaël

2015-07-01

Excessive reactive oxygen species (ROS) is considered a consequence of hyperoxia and a major contributor to diving-derived vascular endothelial damage and decompression sickness. The aims of this work were: 1) to directly observe endothelial ROS production during simulated air dives as well as its relation with both mitochondrial activity and cell survival; and 2) to determine which ambient factor during air diving (hydrostatic pressure or oxygen and/or nitrogen partial pressure) is responsible for the observed modifications. In vitro diving simulation was performed with bovine arterial endothelial cells under real-time observation. The effects of air diving, hydrostatic, oxygen and nitrogen pressures, and N-acetylcysteine (NAC) treatment on mitochondrial ROS generation, mitochondrial membrane potential and cellular survival during simulation were investigated. Vascular endothelial cells performing air diving simulation suffered excessive mitochondrial ROS, mitochondrial depolarization, and cell death. These effects were prevented by NAC: after NAC treatment, the cells presented no difference in damage from nondiving cells. Oxygen diving showed a higher effect on ROS generation but lower impacts on mitochondrial depolarization and cell death than hydrostatic or nitrogen diving. Nitrogen diving had no effect on the inductions of ROS, mito-depolarization, or cell death. This study is the first direct observation of mitochondrial ROS production, mitochondrial membrane potential and cell survival during diving. Simulated air SCUBA diving induces excessive ROS production, which leads to mitochondrial depolarization and endothelial cell death. Oxygen partial pressure plays a crucial role in the production of ROS. Deleterious effects of hyperoxia-induced ROS are potentiated by hydrostatic pressure. These findings hold new implications for the pathogenesis of diving-derived endothelial dysfunction.

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.

Muscle wasting in cancer: the role of mitochondria.

PubMed

Argilés, Josep M; López-Soriano, Francisco J; Busquets, Silvia

2015-05-01

The aim of the present review is to examine the impact of mitochondrial dysfunction in cancer cachexia. Oxidative pathways are altered in this tissue during muscle wasting and this seems to be a consequence of mitochondrial abnormalities that include altered morphology and function, decreased ATP synthesis and uncoupling. An alteration of energy balance is the immediate cause of cachexia. Both alterations in energy intake and expenditure are responsible for the wasting syndrome associated with different types of pathological conditions, such as cancer. Different types of molecular mechanisms contribute to energy expenditure and, therefore, involuntary body weight loss, one of which is mitochondrial dysfunction.

Corneal endothelial dysfunction in Pearson syndrome.

PubMed

Kasbekar, Shivani A; Gonzalez-Martin, Jose A; Shafiq, Ayad E; Chandna, Arvind; Willoughby, Colin E

2013-01-01

Mitochondrial disorders are associated with well recognized ocular manifestations. Pearson syndrome is an often fatal, multisystem, mitochondrial disorder that causes variable bone marrow, hepatic, renal and pancreatic exocrine dysfunction. Phenotypic progression of ocular disease in a 12-year-old male with Pearson syndrome is described. This case illustrates phenotypic drift from Pearson syndrome to Kearns-Sayre syndrome given the patient's longevity. Persistent corneal endothelial failure was noted in addition to ptosis, chronic external ophthalmoplegia and mid-peripheral pigmentary retinopathy. We propose that corneal edema resulting from corneal endothelial metabolic pump failure occurs within a spectrum of mitochondrial disorders.

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

PubMed

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

2018-03-17

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

Mitochondrial dysfunctions in Parkinson's disease.

PubMed

Gautier, C A; Corti, O; Brice, A

2014-05-01

Neurodegenerative disorders (ND) include a wide spectrum of diseases characterized by progressive neuronal dysfunctions or degeneration. With an estimated cost of 135 billion € in 2010 in the European Union (Olesen et al., 2012), they put an enormous economic as well as social burden on modern societies. Hence, they have been the subject of a huge amount of research for the last fifty years. For many of these diseases, our understanding of their profound causes is incomplete and this hinders the discovery of efficient therapies. ND form a highly heterogeneous group of diseases affecting various neuronal subpopulations reflecting different origins and different pathological mechanisms. However, some common themes in the physiopathology of these disorders are emerging. There is growing evidence that mitochondrial dysfunctions play a pivotal role at some point in the course of neurodegeneration. In some cases (e.g. Alzheimer's disease, amyotrophic lateral sclerosis), impairment of mitochondrial functions probably occurs late in the course of the disease. In a subset of ND, current evidence suggests that mitochondrial dysfunctions play a more seminal role in neuronal demise. Parkinson's disease (PD) presents one of the strongest cases based in part on post-mortem studies that have shown mitochondrial impairment (e.g. reduced complex I activity) and oxidative damage in idiopathic PD brains. The occurrence of PD is largely sporadic, but clinical syndromes resembling sporadic PD have been linked to specific environmental insults or to mutations in at least 5 distinct genes (α-synuclein, parkin, DJ-1, PINK1 and LRRK2). It is postulated that the elucidation of the pathogenic mechanisms underlying the selective dopaminergic degeneration in familial and environmental Parkinsonism should provide important clues to the pathogenic mechanisms responsible for idiopathic PD. Hence, numerous cellular and animal models of the disease have been generated that mimic these environmental or genetic insults. The study of these models has yielded valuable information regarding the pathogenic mechanisms underlying dopaminergic degeneration in PD, many of which point towards an involvement of mitochondrial dysfunction. In this short review we will analyze critically the experimental evidence for the mitochondrial origin of PD and evaluate its relevance for our general understanding of the disease. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Vitamin E confers cytoprotective effects on cardiomyocytes under conditions of heat stress by increasing the expression of metallothionein.

PubMed

Wang, Xiaowu; Dong, Wenpeng; Yuan, Binbin; Yang, Yongchao; Yang, Dongpeng; Lin, Xi; Chen, Changfu; Zhang, Weida

2016-05-01

Heat stress (HS) is commonly used to refer to the heat load that an individual is subjected to due to either metabolic heat, or environmental factors, including high temperatures and high humidity levels. HS has been reported to affect and even damage the functioning of various organs; overexposure to high temperatures and high humidity may lead to accidental deaths. It has been suggested that the cardiovascular system is primarily targeted by exposure to HS conditions; the HS-induced dysfunction of cardiomyocytes, which is characterized by mitochondrial dysfunction, may result in the development of cardiovascular diseases. The excessive production of reactive oxygen species (ROS) also participates in mitochondrial dysfunction. However, effective methods for the prevention and treatment of mitochondrial and cardiovascular dysfunction induced by exposure to HS are lacking. In the present study, we hypothesized that vitamin E (VE), an antioxidant, is capable of preventing oxidative stress and mitochondrial injury in cardiomyocytes induced by exposure to HS. The results revealed that pre‑treatment with VE increased the expression of metallothionein (MT), which has previously been reported to confer cytoprotective effects, particularly on the cardiovascular system. Pre-treatment with VE restored mitochondrial function in cardiomyocytes under conditions of HS by increasing the expression of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), and by increasing adenosine triphosphate (ATP) levels. Furthermore, pre-treatment with VE decreased the production of ROS, which was induced by exposure to HS and thus exerted antioxidant effects. In addition, pre-treatment with VE attenuated oxidative stress induced by exposure to HS, as demonstrated by the increased levels of antioxidant enzymes [superoxide dismutase (SOD) and glutathione (GSH)], and by the decreased levels of markers of oxidative injury [malondialdehyde (MDA) and lactate dehydrogenase (LDH)]. Taken together, these findings suggest that pre-treatment with VE can prevent mitochondrial dysfunction and oxidative stress in cardiomyocytes induced by exposure to HS, by increasing the expression of MT.

Mitochondrial Bioenergetics Is Altered in Fibroblasts from Patients with Sporadic Alzheimer's Disease.

PubMed

Pérez, María J; Ponce, Daniela P; Osorio-Fuentealba, Cesar; Behrens, Maria I; Quintanilla, Rodrigo A

2017-01-01

The identification of an early biomarker to diagnose Alzheimer's disease (AD) remains a challenge. Neuropathological studies in animal and AD patients have shown that mitochondrial dysfunction is a hallmark of the development of the disease. Current studies suggest the use of peripheral tissues, like skin fibroblasts as a possibility to detect the early pathological alterations present in the AD brain. In this context, we studied mitochondrial function properties (bioenergetics and morphology) in cultured fibroblasts obtained from AD, aged-match and young healthy patients. We observed that AD fibroblasts presented a significant reduction in mitochondrial length with important changes in the expression of proteins that control mitochondrial fusion. Moreover, AD fibroblasts showed a distinct alteration in proteolytic processing of OPA1, a master regulator of mitochondrial fusion, compared to control fibroblasts. Complementary to these changes AD fibroblasts showed a dysfunctional mitochondrial bioenergetics profile that differentiates these cells from aged-matched and young patient fibroblasts. Our findings suggest that the human skin fibroblasts obtained from AD patients could replicate mitochondrial impairment observed in the AD brain. These promising observations suggest that the analysis of mitochondrial bioenergetics could represent a promising strategy to develop new diagnostic methods in peripheral tissues of AD patients.

Mitochondrial Bioenergetics Is Altered in Fibroblasts from Patients with Sporadic Alzheimer's Disease

PubMed Central

Pérez, María J.; Ponce, Daniela P.; Osorio-Fuentealba, Cesar; Behrens, Maria I.; Quintanilla, Rodrigo A.

2017-01-01

The identification of an early biomarker to diagnose Alzheimer's disease (AD) remains a challenge. Neuropathological studies in animal and AD patients have shown that mitochondrial dysfunction is a hallmark of the development of the disease. Current studies suggest the use of peripheral tissues, like skin fibroblasts as a possibility to detect the early pathological alterations present in the AD brain. In this context, we studied mitochondrial function properties (bioenergetics and morphology) in cultured fibroblasts obtained from AD, aged-match and young healthy patients. We observed that AD fibroblasts presented a significant reduction in mitochondrial length with important changes in the expression of proteins that control mitochondrial fusion. Moreover, AD fibroblasts showed a distinct alteration in proteolytic processing of OPA1, a master regulator of mitochondrial fusion, compared to control fibroblasts. Complementary to these changes AD fibroblasts showed a dysfunctional mitochondrial bioenergetics profile that differentiates these cells from aged-matched and young patient fibroblasts. Our findings suggest that the human skin fibroblasts obtained from AD patients could replicate mitochondrial impairment observed in the AD brain. These promising observations suggest that the analysis of mitochondrial bioenergetics could represent a promising strategy to develop new diagnostic methods in peripheral tissues of AD patients. PMID:29056898

Myocardial dysfunction in mitochondrial diabetes treated with Coenzyme Q10.

PubMed

Salles, João Eduardo; Moisés, Valdir A; Almeida, Dirceu R; Chacra, Antonio R; Moisés, Regina S

2006-04-01

Maternally-inherited diabetes and deafness (MIDD) has been related to an A to G transition in the mitochondrial tRNA Leu (UUR) gene at the base pair 3243. Although some previous articles have reported that this mutation may be a cause of cardiomyopathy in diabetes, the degree of cardiac involvement and a specific treatment has not been established. Here, we reported a case of a patient with MIDD who developed congestive heart failure and the therapeutic usefulness of Coenzyme Q10 (CoQ10). In our patient, after the introduction of Coenzyme Q10 150 mg/day, there was a gradual improvement on left ventricular function evaluated by echocardiography. The fractional shortening (FS) and ejection fraction (EF) increased from 26 to 34% and from 49 to 64%, respectively. No side effects were noted. Three months after CoQ10 discontinuation, the parameters of systolic function evaluated by echocardiography decreased, suggesting that CoQ10 had a beneficial effect. Identification of diabetes and cardiomyopathy due to mitochondrial gene mutation may have therapeutic implications and Coenzyme Q10 is a possible adjunctive treatment in such patients.

Glomerular Endothelial Mitochondrial Dysfunction Is Essential and Characteristic of Diabetic Kidney Disease Susceptibility.

PubMed

Qi, Haiying; Casalena, Gabriella; Shi, Shaolin; Yu, Liping; Ebefors, Kerstin; Sun, Yezhou; Zhang, Weijia; D'Agati, Vivette; Schlondorff, Detlef; Haraldsson, Börje; Böttinger, Erwin; Daehn, Ilse

2017-03-01

The molecular signaling mechanisms between glomerular cell types during initiation/progression of diabetic kidney disease (DKD) remain poorly understood. We compared the early transcriptome profile between DKD-resistant C57BL/6J and DKD-susceptible DBA/2J (D2) glomeruli and demonstrated a significant downregulation of essential mitochondrial genes in glomeruli from diabetic D2 mice, but not in C57BL/6J, with comparable hyperglycemia. Diabetic D2 mice manifested increased mitochondrial DNA lesions (8-oxoguanine) exclusively localized to glomerular endothelial cells after 3 weeks of diabetes, and these accumulated over time in addition to increased urine secretion of 8-oxo-deoxyguanosine. Detailed assessment of glomerular capillaries from diabetic D2 mice demonstrated early signs of endothelial injury and loss of fenestrae. Glomerular endothelial mitochondrial dysfunction was associated with increased glomerular endothelin-1 receptor type A (Ednra) expression and increased circulating endothelin-1 (Edn1). Selective Ednra blockade or mitochondrial-targeted reactive oxygen species scavenging prevented mitochondrial oxidative stress of endothelial cells and ameliorated diabetes-induced endothelial injury, podocyte loss, albuminuria, and glomerulosclerosis. In human DKD, increased urine 8-oxo-deoxyguanosine was associated with rapid DKD progression, and biopsies from patients with DKD showed increased mitochondrial DNA damage associated with glomerular endothelial EDNRA expression. Our studies show that DKD susceptibility was linked to mitochondrial dysfunction, mediated largely by Edn1-Ednra in glomerular endothelial cells representing an early event in DKD progression, and suggest that cross talk between glomerular endothelial injury and podocytes leads to defects and depletion, albuminuria, and glomerulosclerosis. © 2017 by the American Diabetes Association.

TRPM2 Channels Protect against Cardiac Ischemia-Reperfusion Injury

PubMed Central

Miller, Barbara A.; Hoffman, Nicholas E.; Merali, Salim; Zhang, Xue-Qian; Wang, JuFang; Rajan, Sudarsan; Shanmughapriya, Santhanam; Gao, Erhe; Barrero, Carlos A.; Mallilankaraman, Karthik; Song, Jianliang; Gu, Tongda; Hirschler-Laszkiewicz, Iwona; Koch, Walter J.; Feldman, Arthur M.; Madesh, Muniswamy; Cheung, Joseph Y.

2014-01-01

Cardiac TRPM2 channels were activated by intracellular adenosine diphosphate-ribose and blocked by flufenamic acid. In adult cardiac myocytes the ratio of GCa to GNa of TRPM2 channels was 0.56 ± 0.02. To explore the cellular mechanisms by which TRPM2 channels protect against cardiac ischemia/reperfusion (I/R) injury, we analyzed proteomes from WT and TRPM2 KO hearts subjected to I/R. The canonical pathways that exhibited the largest difference between WT-I/R and KO-I/R hearts were mitochondrial dysfunction and the tricarboxylic acid cycle. Complexes I, III, and IV were down-regulated, whereas complexes II and V were up-regulated in KO-I/R compared with WT-I/R hearts. Western blots confirmed reduced expression of the Complex I subunit and other mitochondria-associated proteins in KO-I/R hearts. Bioenergetic analyses revealed that KO myocytes had a lower mitochondrial membrane potential, mitochondrial Ca2+ uptake, ATP levels, and O2 consumption but higher mitochondrial superoxide levels. Additionally, mitochondrial Ca2+ uniporter (MCU) currents were lower in KO myocytes, indicating reduced mitochondrial Ca2+ uptake was likely due to both lower ψm and MCU activity. Similar to isolated myocytes, O2 consumption and ATP levels were also reduced in KO hearts. Under a simulated I/R model, aberrant mitochondrial bioenergetics was exacerbated in KO myocytes. Reactive oxygen species levels were also significantly higher in KO-I/R compared with WT-I/R heart slices, consistent with mitochondrial dysfunction in KO-I/R hearts. We conclude that TRPM2 channels protect the heart from I/R injury by ameliorating mitochondrial dysfunction and reducing reactive oxygen species levels. PMID:24492610

Prolonged Fasting Identifies Skeletal Muscle Mitochondrial Dysfunction as Consequence Rather Than Cause of Human Insulin Resistance

PubMed Central

Hoeks, Joris; van Herpen, Noud A.; Mensink, Marco; Moonen-Kornips, Esther; van Beurden, Denis; Hesselink, Matthijs K.C.; Schrauwen, Patrick

2010-01-01

OBJECTIVE Type 2 diabetes and insulin resistance have been associated with mitochondrial dysfunction, but it is debated whether this is a primary factor in the pathogenesis of the disease. To test the concept that mitochondrial dysfunction is secondary to the development of insulin resistance, we employed the unique model of prolonged fasting in humans. Prolonged fasting is a physiologic condition in which muscular insulin resistance develops in the presence of increased free fatty acid (FFA) levels, increased fat oxidation and low glucose and insulin levels. It is therefore anticipated that skeletal muscle mitochondrial function is maintained to accommodate increased fat oxidation unless factors secondary to insulin resistance exert negative effects on mitochondrial function. RESEARCH DESIGN AND METHODS While in a respiration chamber, twelve healthy males were subjected to a 60 h fast and a 60 h normal fed condition in a randomized crossover design. Afterward, insulin sensitivity was assessed using a hyperinsulinemic-euglycemic clamp, and mitochondrial function was quantified ex vivo in permeabilized muscle fibers using high-resolution respirometry. RESULTS Indeed, FFA levels were increased approximately ninefold after 60 h of fasting in healthy male subjects, leading to elevated intramuscular lipid levels and decreased muscular insulin sensitivity. Despite an increase in whole-body fat oxidation, we observed an overall reduction in both coupled state 3 respiration and maximally uncoupled respiration in permeabilized skeletal muscle fibers, which could not be explained by changes in mitochondrial density. CONCLUSIONS These findings confirm that the insulin-resistant state has secondary negative effects on mitochondrial function. Given the low insulin and glucose levels after prolonged fasting, hyperglycemia and insulin action per se can be excluded as underlying mechanisms, pointing toward elevated plasma FFA and/or intramuscular fat accumulation as possible causes for the observed reduction in mitochondrial capacity. PMID:20573749

Morphological and molecular variations induce mitochondrial dysfunction as a possible underlying mechanism of athletic amenorrhea.

PubMed

Xiong, Ruo-Hong; Wen, Shi-Lei; Wang, Qiang; Zhou, Hong-Ying; Feng, Shi

2018-01-01

Female athletes may experience difficulties in achieving pregnancy due to athletic amenorrhea (AA); however, the underlying mechanisms of AA remain unknown. The present study focuses on the mitochondrial alteration and its function in detecting the possible mechanism of AA. An AA rat model was established by excessive swimming. Hematoxylin and eosin staining, and transmission electron microscopic methods were performed to evaluate the morphological changes of the ovary, immunohistochemical examinations and radioimmunoassays were used to detect the reproductive hormones and corresponding receptors. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to test the mtDNA copy number. PCR and western blot analysis were used to test the expression of ND2. The change of morphological features of the rat ovaries revealed evident abnormalities. Particularly, the features of the mitochondria were markedly altered. In addition, reproductive hormones in the serum and tissues of AA rats were also detected to evaluate the function of the ovaries, and the levels of these hormones were significantly decreased. Furthermore, the mitochondrial DNA copy number (mtDNA) and expression of NADH dehydrogenase subunit 2 (ND2) were quantitated by qPCR or western blot analysis. Accordingly, the mtDNA copy number and expression of ND2 expression were markedly reduced in the AA rats. In conclusion, mitochondrial dysfunction in AA may affect the cellular energy supply and, therefore, result in dysfunction of the ovary. Thus, mitochondrial dysfunction may be considered as a possible underlying mechanism for the occurrence of AA.

Microvascular and mitochondrial dysfunction in the female F1 generation after gestational TiO2 nanoparticle exposure

PubMed Central

Stapleton, Phoebe A.; Nichols, Cody E.; Yi, Jinghai; McBride, Carroll R.; Minarchick, Valerie C.; Shepherd, Danielle L.; Hollander, John M.; Nurkiewicz, Timothy R.

2016-01-01

Due to the ongoing evolution of nanotechnology, there is a growing need to assess the toxicological outcomes in under-studied populations in order to properly consider the potential of engineered nanomaterials (ENM) and fully enhance their safety. Recently, we and others have explored the vascular consequences associated with gestational nanomaterial exposure, reporting microvascular dysfunction within the uterine circulation of pregnant dams and the tail artery of fetal pups. It has been proposed (via work derived by the Barker Hypothesis) that mitochondrial dysfunction and subsequent oxidative stress mechanisms as a possible link between a hostile gestational environment and adult disease. Therefore, in this study, we exposed pregnant Sprague-Dawley rats to nanosized titanium dioxide aerosols after implantation (gestational day 6). Pups were delivered, and the progeny grew into adulthood. Microvascular reactivity, mitochondrial respiration and hydrogen peroxide production of the coronary and uterine circulations of the female offspring were evaluated. While there were no significant differences within the maternal or litter characteristics, endothelium-dependent dilation and active mechanotransduction in both coronary and uterine arterioles were significantly impaired. In addition, there was a significant reduction in maximal mitochondrial respiration (state 3) in the left ventricle and uterus. These studies demonstrate microvascular dysfunction and coincide with mitochondrial inefficiencies in both the cardiac and uterine tissues, which may represent initial evidence that prenatal ENM exposure produces microvascular impairments that persist throughout multiple developmental stages. PMID:25475392

Assessment of nitric oxide production in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome with the use of a stable isotope tracer infusion technique

USDA-ARS?s Scientific Manuscript database

Mitochondrial disorders result from dysfunctional mitochondria that are unable to generate sufficient energy to meet the needs of various organs. Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most frequent maternally inherited mitochondrial...

Intermediate filament aggregates cause mitochondrial dysmotility and increase energy demands in giant axonal neuropathy

PubMed Central

Israeli, Eitan; Dryanovski, Dilyan I.; Schumacker, Paul T.; Chandel, Navdeep S.; Singer, Jeffrey D.; Julien, Jean P.; Goldman, Robert D.; Opal, Puneet

2016-01-01

Intermediate filaments (IFs) are cytoskeletal polymers that extend from the nucleus to the cell membrane, giving cells their shape and form. Abnormal accumulation of IFs is involved in the pathogenesis of number neurodegenerative diseases, but none as clearly as giant axonal neuropathy (GAN), a ravaging disease caused by mutations in GAN, encoding gigaxonin. Patients display early and severe degeneration of the peripheral nervous system along with IF accumulation, but it has been difficult to link GAN mutations to any particular dysfunction, in part because GAN null mice have a very mild phenotype. We therefore established a robust dorsal root ganglion neuronal model that mirrors key cellular events underlying GAN. We demonstrate that gigaxonin is crucial for ubiquitin–proteasomal degradation of neuronal IF. Moreover, IF accumulation impairs mitochondrial motility and is associated with metabolic and oxidative stress. These results have implications for other neurological disorders whose pathology includes IF accumulation. PMID:27000625

Bedside diagnosis of mitochondrial dysfunction after malignant middle cerebral artery infarction.

PubMed

Nielsen, T H; Schalén, W; Ståhl, N; Toft, P; Reinstrup, P; Nordström, C H

2014-08-01

The study explores whether the cerebral biochemical pattern in patients treated with hemicraniectomy after large middle cerebral artery infarcts reflects ongoing ischemia or non-ischemic mitochondrial dysfunction. The study includes 44 patients treated with decompressive hemicraniectomy (DCH) due to malignant middle cerebral artery infarctions. Chemical variables related to energy metabolism obtained by microdialysis were analyzed in the infarcted tissue and in the contralateral hemisphere from the time of DCH until 96 h after DCH. Reperfusion of the infarcted tissue was documented in a previous report. Cerebral lactate/pyruvate ratio (L/P) and lactate were significantly elevated in the infarcted tissue compared to the non-infarcted hemisphere (p < 0.05). From 12 to 96 h after DCH the pyruvate level was significantly higher in the infarcted tissue than in the non-infarcted hemisphere (p < 0.05). After a prolonged period of ischemia and subsequent reperfusion, cerebral tissue shows signs of protracted mitochondrial dysfunction, characterized by a marked increase in cerebral lactate level with a normal or increased cerebral pyruvate level resulting in an increased LP-ratio. This biochemical pattern contrasts to cerebral ischemia, which is characterized by a marked decrease in cerebral pyruvate. The study supports the hypothesis that it is possible to diagnose cerebral mitochondrial dysfunction and to separate it from cerebral ischemia by microdialysis and bed-side biochemical analysis.

A Syntenic Cross Species Aneuploidy Genetic Screen Links RCAN1 Expression to β-Cell Mitochondrial Dysfunction in Type 2 Diabetes

PubMed Central

Peiris, Heshan; Duffield, Michael D.; Fadista, Joao; Kashmir, Vinder; Genders, Amanda J.; McGee, Sean L.; Martin, Alyce M.; Saiedi, Madiha; Morton, Nicholas; Carter, Roderick; Cousin, Michael A.; Oskolkov, Nikolay; Volkov, Petr; Hough, Tertius A.; Fisher, Elizabeth M. C.; Tybulewicz, Victor L. J.; Busciglio, Jorge; Coskun, Pinar E.; Becker, Ann; Belichenko, Pavel V.; Mobley, William C.; Ryan, Michael T.; Chan, Jeng Yie; Laybutt, D. Ross; Coates, P. Toby; Yang, Sijun; Ling, Charlotte; Groop, Leif; Pritchard, Melanie A.; Keating, Damien J.

2016-01-01

Type 2 diabetes (T2D) is a complex metabolic disease associated with obesity, insulin resistance and hypoinsulinemia due to pancreatic β-cell dysfunction. Reduced mitochondrial function is thought to be central to β-cell dysfunction. Mitochondrial dysfunction and reduced insulin secretion are also observed in β-cells of humans with the most common human genetic disorder, Down syndrome (DS, Trisomy 21). To identify regions of chromosome 21 that may be associated with perturbed glucose homeostasis we profiled the glycaemic status of different DS mouse models. The Ts65Dn and Dp16 DS mouse lines were hyperglycemic, while Tc1 and Ts1Rhr mice were not, providing us with a region of chromosome 21 containing genes that cause hyperglycemia. We then examined whether any of these genes were upregulated in a set of ~5,000 gene expression changes we had identified in a large gene expression analysis of human T2D β-cells. This approach produced a single gene, RCAN1, as a candidate gene linking hyperglycemia and functional changes in T2D β-cells. Further investigations demonstrated that RCAN1 methylation is reduced in human T2D islets at multiple sites, correlating with increased expression. RCAN1 protein expression was also increased in db/db mouse islets and in human and mouse islets exposed to high glucose. Mice overexpressing RCAN1 had reduced in vivo glucose-stimulated insulin secretion and their β-cells displayed mitochondrial dysfunction including hyperpolarised membrane potential, reduced oxidative phosphorylation and low ATP production. This lack of β-cell ATP had functional consequences by negatively affecting both glucose-stimulated membrane depolarisation and ATP-dependent insulin granule exocytosis. Thus, from amongst the myriad of gene expression changes occurring in T2D β-cells where we had little knowledge of which changes cause β-cell dysfunction, we applied a trisomy 21 screening approach which linked RCAN1 to β-cell mitochondrial dysfunction in T2D. PMID:27195491

Renal Tubular Cell Mitochondrial Dysfunction Occurs Despite Preserved Renal Oxygen Delivery in Experimental Septic Acute Kidney Injury

PubMed Central

Pollen, Sean; Greco, Elisabetta; Courtneidge, Holly; Hall, Andrew M.; Duchen, Michael R.; Tam, Frederick W. K.; Unwin, Robert J.; Singer, Mervyn

2018-01-01

Objective: To explain the paradigm of significant renal functional impairment despite preserved hemodynamics and histology in sepsis-induced acute kidney injury. Design: Prospective observational animal study. Setting: University research laboratory. Subjects: Male Wistar rats. Intervention: Using a fluid-resuscitated sublethal rat model of fecal peritonitis, changes in renal function were characterized in relation to global and renal hemodynamics, and histology at 6 and 24 hours (n = 6–10). Sham-operated animals were used as comparison (n = 8). Tubular cell mitochondrial function was assessed using multiphoton confocal imaging of live kidney slices incubated in septic serum. Measurements and Main Results: By 24 hours, serum creatinine was significantly elevated with a concurrent decrease in renal lactate clearance in septic animals compared with sham-operated and 6-hour septic animals. Renal uncoupling protein-2 was elevated in septic animals at 24 hours although tubular cell injury was minimal and mitochondrial ultrastructure in renal proximal tubular cells preserved. There was no significant change in global or renal hemodynamics and oxygen delivery/consumption between sham-operated and septic animals at both 6- and 24-hour timepoints. In the live kidney slice model, mitochondrial dysfunction was seen in proximal tubular epithelial cells incubated with septic serum with increased production of reactive oxygen species, and decreases in nicotinamide adenine dinucleotide and mitochondrial membrane potential. These effects were prevented by coincubation with the reactive oxygen species scavenger, 4-hydroxy-2,2,6,6-tetramethyl-piperidin-1-oxyl. Conclusions: Renal dysfunction in sepsis occurs independently of hemodynamic instability or structural damage. Mitochondrial dysfunction mediated by circulating mediators that induce local oxidative stress may represent an important pathophysiologic mechanism. PMID:29293148

Resveratrol induces mitochondrial dysfunction and decreases chronological life span of Saccharomyces cerevisiae in a glucose-dependent manner.

PubMed

Ramos-Gomez, Minerva; Olivares-Marin, Ivanna Karina; Canizal-García, Melina; González-Hernández, Juan Carlos; Nava, Gerardo M; Madrigal-Perez, Luis Alberto

2017-06-01

A broad range of health benefits have been attributed to resveratrol (RSV) supplementation in mammalian systems, including the increases in longevity. Nonetheless, despite the growing number of studies performed with RSV, the molecular mechanism by which it acts still remains unknown. Recently, it has been proposed that inhibition of the oxidative phosphorylation activity is the principal mechanism of RSV action. This mechanism suggests that RSV might induce mitochondrial dysfunction resulting in oxidative damage to cells with a concomitant decrease of cell viability and cellular life span. To prove this hypothesis, the chronological life span (CLS) of Saccharomyces cerevisiae was studied as it is accepted as an important model of oxidative damage and aging. In addition, oxygen consumption, mitochondrial membrane potential, and hydrogen peroxide (H 2 O 2 ) release were measured in order to determine the extent of mitochondrial dysfunction. The results demonstrated that the supplementation of S. cerevisiae cultures with 100 μM RSV decreased CLS in a glucose-dependent manner. At high-level glucose, RSV supplementation increased oxygen consumption during the exponential phase yeast cultures, but inhibited it in chronologically aged yeast cultures. However, at low-level glucose, oxygen consumption was inhibited in yeast cultures in the exponential phase as well as in chronologically aged cultures. Furthermore, RSV supplementation promoted the polarization of the mitochondrial membrane in both cultures. Finally, RSV decreased the release of H 2 O 2 with high-level glucose and increased it at low-level glucose. Altogether, this data supports the hypothesis that RSV supplementation decreases CLS as a result of mitochondrial dysfunction and this phenotype occurs in a glucose-dependent manner.

Naringin ameliorates gentamicin-induced nephrotoxicity and associated mitochondrial dysfunction, apoptosis and inflammation in rats: possible mechanism of nephroprotection.

PubMed

Sahu, Bidya Dhar; Tatireddy, Srujana; Koneru, Meghana; Borkar, Roshan M; Kumar, Jerald Mahesh; Kuncha, Madhusudana; Srinivas, R; Shyam Sunder, R; Sistla, Ramakrishna

2014-05-15

Gentamicin-induced nephrotoxicity has been well documented, although its underlying mechanisms and preventive strategies remain to be investigated. The present study was designed to investigate the protective effect of naringin, a bioflavonoid, on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific renal function parameters (blood urea nitrogen and creatinine) and histopathology of kidney tissues were evaluated to assess the gentamicin-induced nephrotoxicity. Renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic and non-enzymatic antioxidants), inflammatory (NF-kB [p65], TNF-α, IL-6 and MPO) and apoptotic (caspase 3, caspase 9, Bax, Bcl-2, p53 and DNA fragmentation) markers were also evaluated. Significant decrease in mitochondrial NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity indicated the gentamicin-induced mitochondrial dysfunction. Naringin (100mg/kg) treatment along with gentamicin restored the mitochondrial function and increased the renal endogenous antioxidant status. Gentamicin induced increased renal inflammatory cytokines (TNF-α and IL-6), nuclear protein expression of NF-κB (p65) and NF-κB-DNA binding activity and myeloperoxidase (MPO) activity were significantly decreased upon naringin treatment. In addition, naringin treatment significantly decreased the amount of cleaved caspase 3, Bax, and p53 protein expression and increased the Bcl-2 protein expression. Naringin treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. U-HPLS-MS data revealed that naringin co-administration along with gentamicin did not alter the renal uptake and/or accumulation of gentamicin in kidney tissues. These findings suggest that naringin treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, mitochondrial dysfunction, inflammation and apoptosis in the kidney. Copyright © 2014 Elsevier Inc. All rights reserved.

Human biallelic MFN2 mutations induce mitochondrial dysfunction, upper body adipose hyperplasia, and suppression of leptin expression.

PubMed

Rocha, Nuno; Bulger, David A; Frontini, Andrea; Titheradge, Hannah; Gribsholt, Sigrid Bjerge; Knox, Rachel; Page, Matthew; Harris, Julie; Payne, Felicity; Adams, Claire; Sleigh, Alison; Crawford, John; Gjesing, Anette Prior; Bork-Jensen, Jette; Pedersen, Oluf; Barroso, Inês; Hansen, Torben; Cox, Helen; Reilly, Mary; Rossor, Alex; Brown, Rebecca J; Taylor, Simeon I; McHale, Duncan; Armstrong, Martin; Oral, Elif A; Saudek, Vladimir; O'Rahilly, Stephen; Maher, Eamonn R; Richelsen, Bjørn; Savage, David B; Semple, Robert K

2017-04-19

MFN2 encodes mitofusin 2, a membrane-bound mediator of mitochondrial membrane fusion and inter-organelle communication. MFN2 mutations cause axonal neuropathy, with associated lipodystrophy only occasionally noted, however homozygosity for the p.Arg707Trp mutation was recently associated with upper body adipose overgrowth. We describe similar massive adipose overgrowth with suppressed leptin expression in four further patients with biallelic MFN2 mutations and at least one p.Arg707Trp allele. Overgrown tissue was composed of normal-sized, UCP1-negative unilocular adipocytes, with mitochondrial network fragmentation, disorganised cristae, and increased autophagosomes. There was strong transcriptional evidence of mitochondrial stress signalling, increased protein synthesis, and suppression of signatures of cell death in affected tissue, whereas mitochondrial morphology and gene expression were normal in skin fibroblasts. These findings suggest that specific MFN2 mutations cause tissue-selective mitochondrial dysfunction with increased adipocyte proliferation and survival, confirm a novel form of excess adiposity with paradoxical suppression of leptin expression, and suggest potential targeted therapies.

Oxidative Stress and Mitochondrial Dysfunction across Broad-Ranging Pathologies: Toward Mitochondria-Targeted Clinical Strategies

PubMed Central

d'Ischia, Marco; Gadaleta, Maria Nicola; Pallardó, Federico V.; Petrović, Sandra; Tiano, Luca; Zatterale, Adriana

2014-01-01

Beyond the disorders recognized as mitochondrial diseases, abnormalities in function and/or ultrastructure of mitochondria have been reported in several unrelated pathologies. These encompass ageing, malformations, and a number of genetic or acquired diseases, as diabetes and cardiologic, haematologic, organ-specific (e.g., eye or liver), neurologic and psychiatric, autoimmune, and dermatologic disorders. The mechanistic grounds for mitochondrial dysfunction (MDF) along with the occurrence of oxidative stress (OS) have been investigated within the pathogenesis of individual disorders or in groups of interrelated disorders. We attempt to review broad-ranging pathologies that involve mitochondrial-specific deficiencies or rely on cytosol-derived prooxidant states or on autoimmune-induced mitochondrial damage. The established knowledge in these subjects warrants studies aimed at elucidating several open questions that are highlighted in the present review. The relevance of OS and MDF in different pathologies may establish the grounds for chemoprevention trials aimed at compensating OS/MDF by means of antioxidants and mitochondrial nutrients. PMID:24876913

Mitochondrial biotransformation of ω-(phenoxy)alkanoic acids, 3-(phenoxy)acrylic acids, and ω-(1-methyl-1H-imidazol-2-ylthio)alkanoic acids: A prodrug strategy for targeting cytoprotective antioxidants to mitochondria

PubMed Central

Roser, Kurt S.; Brookes, Paul S.; Wojtovich, Andrew P.; Olson, Leif P.; Shojaie, Jalil; Parton, Richard L.; Anders, M. W.

2010-01-01

Mitochondrial reactive oxygen species (ROS) generation and the attendant mitochondrial dysfunction are implicated in a range of disease states. The objective of the present studies was to test the hypothesis that the mitochondrial β-oxidation pathway could be exploited to deliver and biotransform the prodrugs ω-(phenoxy)alkanoic acids, 3-(phenoxy)acrylic acids, and ω-(1-methyl-1H-imidazol-2-ylthio)alkanoic acids to the corresponding phenolic antioxidants or methimazole. 3 -and 5-(Phenoxy)alkanoic acids and methyl-substituted analogs were biotransformed to phenols; rates of biotransformation decreased markedly with methyl-group substitution on the phenoxy moiety. 2,6-Dimethylphenol formation from the analogs 3-([2,6-dimethylphenoxy]methylthio)propanoic acid and 3-(2,6-dimethylphenoxy)acrylic acid was greater than that observed with ω-(2,6-dimethylphenoxy)alkanoic acids. 3- and 5-(1-Methyl-1H-imidazol-2-ylthio)alkanoic acids were rapidly biotransformed to the antioxidant methimazole and conferred significant cytoprotection against hypoxia-reoxygenation injury in isolated cardiomyocytes. Both 3-(2,6-dimethylphenoxy)propanoic acid and 3-(2,6-dimethylphenoxy)acrylic acid also afforded cytoprotection against hypoxia-reoxygenation injury in isolated cardiomyocytes. These results demonstrate that mitochondrial β-oxidation is a potentially useful delivery system for targeting antioxidants to mitochondria. PMID:20129794

Skeletal muscle proteomic signature and metabolic impairment in pulmonary hypertension.

PubMed

Malenfant, Simon; Potus, François; Fournier, Frédéric; Breuils-Bonnet, Sandra; Pflieger, Aude; Bourassa, Sylvie; Tremblay, Ève; Nehmé, Benjamin; Droit, Arnaud; Bonnet, Sébastien; Provencher, Steeve

2015-05-01

Exercise limitation comes from a close interaction between cardiovascular and skeletal muscle impairments. To better understand the implication of possible peripheral oxidative metabolism dysfunction, we studied the proteomic signature of skeletal muscle in pulmonary arterial hypertension (PAH). Eight idiopathic PAH patients and eight matched healthy sedentary subjects were evaluated for exercise capacity, skeletal muscle proteomic profile, metabolism, and mitochondrial function. Skeletal muscle proteins were extracted, and fractioned peptides were tagged using an iTRAQ protocol. Proteomic analyses have documented a total of 9 downregulated proteins in PAH skeletal muscles and 10 upregulated proteins compared to healthy subjects. Most of the downregulated proteins were related to mitochondrial structure and function. Focusing on skeletal muscle metabolism and mitochondrial health, PAH patients presented a decreased expression of oxidative enzymes (pyruvate dehydrogenase, p < 0.01) and an increased expression of glycolytic enzymes (lactate dehydrogenase activity, p < 0.05). These findings were supported by abnormal mitochondrial morphology on electronic microscopy, lower citrate synthase activity (p < 0.01) and lower expression of the transcription factor A of the mitochondria (p < 0.05), confirming a more glycolytic metabolism in PAH skeletal muscles. We provide evidences that impaired mitochondrial and metabolic functions found in the lungs and the right ventricle are also present in skeletal muscles of patients. • Proteomic and metabolic analysis show abnormal oxidative metabolism in PAH skeletal muscle. • EM of PAH patients reveals abnormal mitochondrial structure and distribution. • Abnormal mitochondrial health and function contribute to exercise impairments of PAH. • PAH may be considered a vascular affliction of heart and lungs with major impact on peripheral muscles.

Carnitine insufficiency caused by aging and overnutrition compromises mitochondrial performance and metabolic control.

PubMed

Noland, Robert C; Koves, Timothy R; Seiler, Sarah E; Lum, Helen; Lust, Robert M; Ilkayeva, Olga; Stevens, Robert D; Hegardt, Fausto G; Muoio, Deborah M

2009-08-21

In addition to its essential role in permitting mitochondrial import and oxidation of long chain fatty acids, carnitine also functions as an acyl group acceptor that facilitates mitochondrial export of excess carbons in the form of acylcarnitines. Recent evidence suggests carnitine requirements increase under conditions of sustained metabolic stress. Accordingly, we hypothesized that carnitine insufficiency might contribute to mitochondrial dysfunction and obesity-related impairments in glucose tolerance. Consistent with this prediction whole body carnitine diminution was identified as a common feature of insulin-resistant states such as advanced age, genetic diabetes, and diet-induced obesity. In rodents fed a lifelong (12 month) high fat diet, compromised carnitine status corresponded with increased skeletal muscle accumulation of acylcarnitine esters and diminished hepatic expression of carnitine biosynthetic genes. Diminished carnitine reserves in muscle of obese rats was accompanied by marked perturbations in mitochondrial fuel metabolism, including low rates of complete fatty acid oxidation, elevated incomplete beta-oxidation, and impaired substrate switching from fatty acid to pyruvate. These mitochondrial abnormalities were reversed by 8 weeks of oral carnitine supplementation, in concert with increased tissue efflux and urinary excretion of acetylcarnitine and improvement of whole body glucose tolerance. Acetylcarnitine is produced by the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT). A role for this enzyme in combating glucose intolerance was further supported by the finding that CrAT overexpression in primary human skeletal myocytes increased glucose uptake and attenuated lipid-induced suppression of glucose oxidation. These results implicate carnitine insufficiency and reduced CrAT activity as reversible components of the metabolic syndrome.

Carnitine Insufficiency Caused by Aging and Overnutrition Compromises Mitochondrial Performance and Metabolic Control*

PubMed Central

Noland, Robert C.; Koves, Timothy R.; Seiler, Sarah E.; Lum, Helen; Lust, Robert M.; Ilkayeva, Olga; Stevens, Robert D.; Hegardt, Fausto G.; Muoio, Deborah M.

2009-01-01

In addition to its essential role in permitting mitochondrial import and oxidation of long chain fatty acids, carnitine also functions as an acyl group acceptor that facilitates mitochondrial export of excess carbons in the form of acylcarnitines. Recent evidence suggests carnitine requirements increase under conditions of sustained metabolic stress. Accordingly, we hypothesized that carnitine insufficiency might contribute to mitochondrial dysfunction and obesity-related impairments in glucose tolerance. Consistent with this prediction whole body carnitine dimunition was identified as a common feature of insulin-resistant states such as advanced age, genetic diabetes, and diet-induced obesity. In rodents fed a lifelong (12 month) high fat diet, compromised carnitine status corresponded with increased skeletal muscle accumulation of acylcarnitine esters and diminished hepatic expression of carnitine biosynthetic genes. Diminished carnitine reserves in muscle of obese rats was accompanied by marked perturbations in mitochondrial fuel metabolism, including low rates of complete fatty acid oxidation, elevated incomplete β-oxidation, and impaired substrate switching from fatty acid to pyruvate. These mitochondrial abnormalities were reversed by 8 weeks of oral carnitine supplementation, in concert with increased tissue efflux and urinary excretion of acetylcarnitine and improvement of whole body glucose tolerance. Acetylcarnitine is produced by the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT). A role for this enzyme in combating glucose intolerance was further supported by the finding that CrAT overexpression in primary human skeletal myocytes increased glucose uptake and attenuated lipid-induced suppression of glucose oxidation. These results implicate carnitine insufficiency and reduced CrAT activity as reversible components of the metabolic syndrome. PMID:19553674

Activity-Based Protein Profiling Reveals Mitochondrial Oxidative Enzyme Impairment and Restoration in Diet-Induced Obese Mice

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

Sadler, Natalie C.; Angel, Thomas E.; Lewis, Michael P.

High-fat diet (HFD) induced obesity and concomitant development of insulin resistance (IR) and type 2 diabetes mellitus have been linked to mitochondrial dysfunction. However, it is not clear whether mitochondrial dysfunction is a direct effect of a HFD or if the mitochondrial function is reduced with increased HFD duration. We hypothesized that the function of mitochondrial oxidative and lipid metabolism functions in skeletal muscle mitochondria for HFD mice are similar or elevated relative to standard diet (SD) mice, thereby IR is neither cause nor consequence of mitochondrial dysfunction. We applied a chemical probe approach to identify functionally reactive ATPases andmore » nucleotide-binding proteins in mitochondria isolated from skeletal muscle of C57Bl/6J mice fed HFD or SD chow for 2-, 8-, or 16-weeks; feeding time points known to induce IR. A total of 293 probe-labeled proteins were identified by mass spectrometry-based proteomics, of which 54 differed in abundance between HFD and SD mice. We found proteins associated with the TCA cycle, oxidative phosphorylation (OXPHOS), and lipid metabolism were altered in function when comparing SD to HFD fed mice at 2-weeks, however by 16-weeks HFD mice had TCA cycle, β-oxidation, and respiratory chain function at levels similar to or higher than SD mice.« less

KM-34, a Novel Antioxidant Compound, Protects against 6-Hydroxydopamine-Induced Mitochondrial Damage and Neurotoxicity.

PubMed

Fonseca-Fonseca, Luis Arturo; Nuñez-Figueredo, Yanier; Sánchez, Jeney Ramírez; Guerra, Maylin Wong; Ochoa-Rodríguez, Estael; Verdecia-Reyes, Yamila; Hernádez, René Delgado; Menezes-Filho, Noelio J; Costa, Teresa Cristina Silva; de Santana, Wagno Alcântara; Oliveira, Joana L; Segura-Aguilar, Juan; da Silva, Victor Diogenes Amaral; Costa, Silva Lima

2018-01-02

The etiology of Parkinson's disease is not completely understood and is believed to be multifactorial. Neuronal disorders associated to oxidative stress and mitochondrial dysfunction are widely considered major consequences. The aim of this study was to investigate the effect of the synthetic arylidenmalonate derivative 5-(3,4-dihydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (KM-34), in oxidative stress and mitochondrial dysfunction induced by 6-hydroxydopamine (6-OHDA). Pretreatment (2 h) with KM-34 (1 and 10 μM) markedly attenuated 6-OHDA-induced PC12 cell death in a concentration-dependent manner. KM-34 also inhibited H 2 O 2 generation, mitochondrial swelling, and membrane potential dissipation after 6-OHDA-induced mitochondrial damage. In vivo, KM-34 treatment (1 and 2 mg/Kg) reduced percentage of asymmetry (cylinder test) and increased the vertical exploration (open field) with respect to untreated injured animals; KM-34 also reduced glial fibrillary acidic protein overexpression and increased tyrosine hydroxylase-positive cell number, both in substantia nigra pars compacta. These results demonstrate that KM-34 present biological effects associated to mitoprotection and neuroprotection in vitro, moreover, glial response and neuroprotection in SNpc in vivo. We suggest that KM-34 could be a putative neuroprotective agent for inhibiting the progressive neurodegenerative disease associated to oxidative stress and mitochondrial dysfunction.

Alda-1 Protects Against Acrolein-Induced Acute Lung Injury and Endothelial Barrier Dysfunction.

PubMed

Lu, Qing; Mundy, Miles; Chambers, Eboni; Lange, Thilo; Newton, Julie; Borgas, Diana; Yao, Hongwei; Choudhary, Gaurav; Basak, Rajshekhar; Oldham, Mahogany; Rounds, Sharon

2017-12-01

Inhalation of acrolein, a highly reactive aldehyde, causes lung edema. The underlying mechanism is poorly understood and there is no effective treatment. In this study, we demonstrated that acrolein not only dose-dependently induced lung edema but also promoted LPS-induced acute lung injury. Importantly, acrolein-induced lung injury was prevented and rescued by Alda-1, an activator of mitochondrial aldehyde dehydrogenase 2. Acrolein also dose-dependently increased monolayer permeability, disrupted adherens junctions and focal adhesion complexes, and caused intercellular gap formation in primary cultured lung microvascular endothelial cells (LMVECs). These effects were attenuated by Alda-1 and the antioxidant N-acetylcysteine, but not by the NADPH inhibitor apocynin. Furthermore, acrolein inhibited AMP-activated protein kinase (AMPK) and increased mitochondrial reactive oxygen species levels in LMVECs-effects that were associated with impaired mitochondrial respiration. AMPK total protein levels were also reduced in lung tissue of mice and LMVECs exposed to acrolein. Activation of AMPK with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside blunted an acrolein-induced increase in endothelial monolayer permeability, but not mitochondrial oxidative stress or inhibition of mitochondrial respiration. Our results suggest that acrolein-induced mitochondrial dysfunction may not contribute to endothelial barrier dysfunction. We speculate that detoxification of acrolein by Alda-1 and activation of AMPK may be novel approaches to prevent and treat acrolein-associated acute lung injury, which may occur after smoke inhalation.

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

PubMed

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

2016-06-01

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

Mitochondrial biogenesis: pharmacological approaches.

PubMed

Valero, Teresa

2014-01-01

Organelle biogenesis is concomitant to organelle inheritance during cell division. It is necessary that organelles double their size and divide to give rise to two identical daughter cells. Mitochondrial biogenesis occurs by growth and division of pre-existing organelles and is temporally coordinated with cell cycle events [1]. However, mitochondrial biogenesis is not only produced in association with cell division. It can be produced in response to an oxidative stimulus, to an increase in the energy requirements of the cells, to exercise training, to electrical stimulation, to hormones, during development, in certain mitochondrial diseases, etc. [2]. Mitochondrial biogenesis is therefore defined as the process via which cells increase their individual mitochondrial mass [3]. Recent discoveries have raised attention to mitochondrial biogenesis as a potential target to treat diseases which up to date do not have an efficient cure. Mitochondria, as the major ROS producer and the major antioxidant producer exert a crucial role within the cell mediating processes such as apoptosis, detoxification, Ca2+ buffering, etc. This pivotal role makes mitochondria a potential target to treat a great variety of diseases. Mitochondrial biogenesis can be pharmacologically manipulated. This issue tries to cover a number of approaches to treat several diseases through triggering mitochondrial biogenesis. It contains recent discoveries in this novel field, focusing on advanced mitochondrial therapies to chronic and degenerative diseases, mitochondrial diseases, lifespan extension, mitohormesis, intracellular signaling, new pharmacological targets and natural therapies. It contributes to the field by covering and gathering the scarcely reported pharmacological approaches in the novel and promising field of mitochondrial biogenesis. There are several diseases that have a mitochondrial origin such as chronic progressive external ophthalmoplegia (CPEO) and the Kearns- Sayre syndrome (KSS), myoclonic epilepsy with ragged-red fibers (MERRF), mitochondrial encephalomyopathy, lactic acidosis and strokelike episodes (MELAS), Leber's hereditary optic neuropathy (LHON), the syndrome of neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP), and Leigh's syndrome. Likewise, other diseases in which mitochondrial dysfunction plays a very important role include neurodegenerative diseases, diabetes or cancer. Generally, in mitochondrial diseases a mutation in the mitochondrial DNA leads to a loss of functionality of the OXPHOS system and thus to a depletion of ATP and overproduction of ROS, which can, in turn, induce further mtDNA mutations. The work by Yu-Ting Wu, Shi-Bei Wu, and Yau-Huei Wei (Department of Biochemistry and Molecular Biology, National Yang-Ming University, Taiwan) [4] focuses on the aforementioned mitochondrial diseases with special attention to the compensatory mechanisms that prompt mitochondria to produce more energy even under mitochondrial defect-conditions. These compensatory mechanisms include the overexpression of antioxidant enzymes, mitochondrial biogenesis and overexpression of respiratory complex subunits, as well as metabolic shift to glycolysis. The pathways observed to be related to mitochondrial biogenesis as a compensatory adaptation to the energetic deficits in mitochondrial diseases are described (PGC- 1, Sirtuins, AMPK). Several pharmacological strategies to trigger these signaling cascades, according to these authors, are the use of bezafibrate to activate the PPAR-PGC-1α axis, the activation of AMPK by resveratrol and the use of Sirt1 agonists such as quercetin or resveratrol. Other strategies currently used include the addition of antioxidant supplements to the diet (dietary supplementation with antioxidants) such as L-carnitine, coenzyme Q10,MitoQ10 and other mitochondria-targeted antioxidants,N-acetylcysteine (NAC), vitamin C, vitamin E vitamin K1, vitamin B, sodium pyruvate or -lipoic acid. As aforementioned, other diseases do not have exclusively a mitochondrial origin but they might have an important mitochondrial component both on their onset and on their development. This is the case of type 2 diabetes or neurodegenerative diseases. Type 2 diabetes is characterized by a peripheral insulin resistance accompanied by an increased secretion of insulin as a compensatory system. Among the explanations about the origin of insulin resistance Mónica Zamora and Josep A. Villena (Department of Experimental and Health Sciences, Universitat Pompeu Fabra / Laboratory of Metabolism and Obesity, Universitat Autònoma de Barcelona, Spain) [5] consider the hypothesis that mitochondrial dysfunction, e.g. impaired (mitochondrial) oxidative capacity of the cell or tissue, is one of the main underlying causes of insulin resistance and type 2 diabetes. Although this hypothesis is not free of controversy due to the uncertainty on the sequence of events during type 2 diabetes onset, e.g. whether mitochondrial dysfunction is the cause or the consequence of insulin resistance, it has been widely observed that improving mitochondrial function also improves insulin sensitivity and prevents type 2 diabetes. Thus restoring oxidative capacity by increasing mitochondrial mass appears as a suitable strategy to treat insulin resistance. The effort made by researchers trying to understand the signaling pathways mediating mitochondrial biogenesis has uncovered new potential pharmacological targets and opens the perspectives for the design of suitable treatments for insulin resistance. In addition some of the current used strategies could be used to treat insulin resistance such as lifestyle interventions (caloric restriction and endurance exercise) and pharmacological interventions (thiazolidinediones and other PPAR agonists, resveratrol and other calorie restriction mimetics, AMPK activators, ERR activators). Mitochondrial biogenesis is of special importance in modern neurochemistry because of the broad spectrum of human diseases arising from defects in mitochondrial ion and ROS homeostasis, energy production and morphology [1]. Parkinson´s Disease (PD) is a very good example of this important mitochondrial component on neurodegenerative diseases. Anuradha Yadav, Swati Agrawal, Shashi Kant Tiwari, and Rajnish K. Chaturvedi (CSIR-Indian Institute of Toxicology Research / Academy of Scientific and Innovative Research, India) [6] remark in their review the role of mitochondrial dysfunction in PD with special focus on the role of oxidative stress and bioenergetic deficits. These alterations may have their origin on pathogenic gene mutations in important genes such as DJ-1, -syn, parkin, PINK1 or LRRK2. These mutations, in turn, may cause defects in mitochondrial dynamics (key events like fission/fusion, biogenesis, trafficking in retrograde and anterograde directions, and mitophagy). This work reviews different strategies to enhance mitochondrial bioenergetics in order to ameliorate the neurodegenerative process, with an emphasis on clinical trials reports that indicate their potential. Among them creatine, Coenzyme Q10 and mitochondrial targeted antioxidants/peptides are reported to have the most remarkable effects in clinical trials. They highlight a dual effect of PGC-1α expression on PD prognosis. Whereas a modest expression of this transcriptional co-activator results in positive effects, a moderate to substantial overexpession may have deleterious consequences. As strategies to induce PGC-1α activation, these authors remark the possibility to activate Sirt1 with resveratrol, to use PPAR agonists such as pioglitazone, rosiglitazone, fenofibrate and bezafibrate. Other strategies include the triggering of Nrf2/antioxidant response element (ARE) pathway by triterpenoids (derivatives of oleanolic acid) or by Bacopa monniera, the enhancement of ATP production by carnitine and -lipoic acid. Mitochondrial dysfunctions are the prime source of neurodegenerative diseases and neurodevelopmental disorders. In the context of neural differentiation, Martine Uittenbogaard and Anne Chiaramello (Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, USA) [7] thoroughly describe the implication of mitochondrial biogenesis on neuronal differentiation, its timing, its regulation by specific signaling pathways and new potential therapeutic strategies. The maintenance of mitochondrial homeostasis is crucial for neuronal development. A mitochondrial dynamic balance is necessary between mitochondrial fusion, fission and quality control systems and mitochondrial biogenesis. Concerning the signaling pathways leading to mitochondrial biogenesis this review highlights the implication of different regulators such as AMPK, SIRT1, PGC-1α, NRF1, NRF2, Tfam, etc. on the specific case of neuronal development, providing examples of diseases in which these pathways are altered and transgenic mouse models lacking these regulators. A common hallmark of several neurodegenerative diseases (Huntington´s Disease, Alzheimer´s Disease and Parkinson´s Disease) is the impaired function or expression of PGC-1α, the master regulator of mitochondrial biogenesis. Among the promising strategies to ameliorate mitochondrial-based diseases these authors highlight the induction of PGC-1α via activation of PPAR receptors (rosiglitazone, bezafibrate) or modulating its activity by AMPK (AICAR, metformin, resveratrol) or SIRT1 (SRT1720 and several isoflavone-derived compounds). This article also presents a review of the current animal and cellular models useful to study mitochondriogenesis. Although it is known that many neurodegenerative and neurodevelopmental diseases are originated in mitochondria, the regulation of mitochondrial biogenesis has never been extensively studied. (ABSTRACT TRUNCATED)

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.

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.

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.

Kynurenine pathway metabolites and enzymes involved in redox reactions.

PubMed

González Esquivel, D; Ramírez-Ortega, D; Pineda, B; Castro, N; Ríos, C; Pérez de la Cruz, V

2017-01-01

Oxido-reduction reactions are a fundamental part of the life due to support many vital biological processes as cellular respiration and glucose oxidation. In the redox reactions, one substance transfers one or more electrons to another substance. An important electron carrier is the coenzyme NAD + , which is involved in many metabolic pathways. De novo biosynthesis of NAD + is through the kynurenine pathway, the major route of tryptophan catabolism, which is sensitive to redox environment and produces metabolites with redox capacity, able to alter biological functions that are controlled by redox-responsive signaling pathways. Kynurenine pathway metabolites have been implicated in the physiology process and in the physiopathology of many diseases; processes that also share others factors as dysregulation of calcium homeostasis, mitochondrial dysfunction, oxidative stress, inflammation and cell death, which impact the redox environment. This review examines in detail the available evidence in which kynurenine pathway metabolites participate in redox reactions and their effect on cellular redox homeostasis, since the knowledge of the main factors and mechanisms that lead to cell death in many neurodegenative disorders and other pathologies, such as mitochondrial dysfunction, oxidative stress and kynurenines imbalance, will allow to develop therapies using them as targets. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'. Copyright © 2016 Elsevier Ltd. All rights reserved.

Galactose enhances oxidative metabolism and reveals mitochondrial dysfunction in human primary muscle cells.

PubMed

Aguer, Céline; Gambarotta, Daniela; Mailloux, Ryan J; Moffat, Cynthia; Dent, Robert; McPherson, Ruth; Harper, Mary-Ellen

2011-01-01

Human primary myotubes are highly glycolytic when cultured in high glucose medium rendering it difficult to study mitochondrial dysfunction. Galactose is known to enhance mitochondrial metabolism and could be an excellent model to study mitochondrial dysfunction in human primary myotubes. The aim of the present study was to 1) characterize the effect of differentiating healthy human myoblasts in galactose on oxidative metabolism and 2) determine whether galactose can pinpoint a mitochondrial malfunction in post-diabetic myotubes. Oxygen consumption rate (OCR), lactate levels, mitochondrial content, citrate synthase and cytochrome C oxidase activities, and AMPK phosphorylation were determined in healthy myotubes differentiated in different sources/concentrations of carbohydrates: 25 mM glucose (high glucose (HG)), 5 mM glucose (low glucose (LG)) or 10 mM galactose (GAL). Effect of carbohydrates on OCR was also determined in myotubes derived from post-diabetic patients and matched obese non-diabetic subjects. OCR was significantly increased whereas anaerobic glycolysis was significantly decreased in GAL myotubes compared to LG or HG myotubes. This increased OCR in GAL myotubes occurred in conjunction with increased cytochrome C oxidase activity and expression, as well as increased AMPK phosphorylation. OCR of post-diabetic myotubes was not different than that of obese non-diabetic myotubes when differentiated in LG or HG. However, whereas GAL increased OCR in obese non-diabetic myotubes, it did not affect OCR in post-diabetic myotubes, leading to a significant difference in OCR between groups. The lack of an increase in OCR in post-diabetic myotubes differentiated in GAL was in relation with unaltered cytochrome C oxidase activity levels or AMPK phosphorylation. Our results indicate that differentiating human primary myoblasts in GAL enhances aerobic metabolism. Because this cell culture model elicited an abnormal response in cells from post-diabetic patients, it may be useful in further studies of the molecular mechanisms of mitochondrial dysfunction.

Novel role of NOX in supporting aerobic glycolysis in cancer cells with mitochondrial dysfunction and as a potential target for cancer therapy.

PubMed

Lu, Weiqin; Hu, Yumin; Chen, Gang; Chen, Zhao; Zhang, Hui; Wang, Feng; Feng, Li; Pelicano, Helene; Wang, Hua; Keating, Michael J; Liu, Jinsong; McKeehan, Wallace; Wang, Huamin; Luo, Yongde; Huang, Peng

2012-01-01

Elevated aerobic glycolysis in cancer cells (the Warburg effect) may be attributed to respiration injury or mitochondrial dysfunction, but the underlying mechanisms and therapeutic significance remain elusive. Here we report that induction of mitochondrial respiratory defect by tetracycline-controlled expression of a dominant negative form of DNA polymerase γ causes a metabolic shift from oxidative phosphorylation to glycolysis and increases ROS generation. We show that upregulation of NOX is critical to support the elevated glycolysis by providing additional NAD+. The upregulation of NOX is also consistently observed in cancer cells with compromised mitochondria due to the activation of oncogenic Ras or loss of p53, and in primary pancreatic cancer tissues. Suppression of NOX by chemical inhibition or genetic knockdown of gene expression selectively impacts cancer cells with mitochondrial dysfunction, leading to a decrease in cellular glycolysis, a loss of cell viability, and inhibition of cancer growth in vivo. Our study reveals a previously unrecognized function of NOX in cancer metabolism and suggests that NOX is a potential novel target for cancer treatment.

Global loss of acetylcholinesterase activity with mitochondrial complexes inhibition and inflammation in brain of hypercholesterolemic mice.

PubMed

Paul, Rajib; Borah, Anupom

2017-12-20

There exists an intricate relationship between hypercholesterolemia (elevated plasma cholesterol) and brain functions. The present study aims to understand the impact of hypercholesterolemia on pathological consequences in mouse brain. A chronic mouse model of hypercholesterolemia was induced by giving high-cholesterol diet for 12 weeks. The hypercholesterolemic mice developed cognitive impairment as evident from object recognition memory test. Cholesterol accumulation was observed in four discrete brain regions, such as cortex, striatum, hippocampus and substantia nigra along with significantly damaged blood-brain barrier by hypercholesterolemia. The crucial finding is the loss of acetylcholinesterase activity with mitochondrial dysfunction globally in the brain of hypercholesterolemic mice, which is related to the levels of cholesterol. Moreover, the levels of hydroxyl radical were elevated in the regions of brain where the activity of mitochondrial complexes was found to be reduced. Intriguingly, elevations of inflammatory stress markers in the cholesterol-rich brain regions were observed. As cognitive impairment, diminished brain acetylcholinesterase activity, mitochondrial dysfunctions, and inflammation are the prima facie pathologies of neurodegenerative diseases, the findings impose hypercholesterolemia as potential risk factor towards brain dysfunction.

Neuroprotective effects of ginsenoside Rb1 on high glucose-induced neurotoxicity in primary cultured rat hippocampal neurons.

PubMed

Liu, Di; Zhang, Hong; Gu, Wenjuan; Liu, Yuqin; Zhang, Mengren

2013-01-01

Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects. Endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, so the present study aimed to observe the effects of ginsenoside Rb1 on ER stress signaling pathways in high glucose-treated hippocampal neurons. The results from MTT, TUNEL labeling and Annexin V-FITC/PI/Hoechst assays showed that incubating neurons with 50 mM high glucose for 72 h decreased cell viability and increased the number of apoptotic cells whereas treating neurons with 1 μM Rb1 for 72 h protected the neurons against high glucose-induced cell damage. Further molecular mechanism study demonstrated that Rb1 suppressed the activation of ER stress-associated proteins including protein kinase RNA (PKR)-like ER kinase (PERK) and C/EBP homology protein (CHOP) and downregulation of Bcl-2 induced by high glucose. Moreover, Rb1 inhibited both the elevation of intracellular reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential induced by high glucose. In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC). In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

Chicken or the egg: Warburg effect and mitochondrial dysfunction

PubMed Central

Senyilmaz, Deniz

2015-01-01

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

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

PubMed

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

2018-06-01

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

Effects of Astragalus Polysaccharides on Dysfunction of Mitochondrial Dynamics Induced by Oxidative Stress.

PubMed

Huang, Yan-Feng; Lu, Lu; Zhu, Da-Jian; Wang, Ming; Yin, Yi; Chen, De-Xiu; Wei, Lian-Bo

2016-01-01

This paper studied the chronic fatigue induced by excessive exercise and the restoration effects of Astragalus polysaccharides (APS) on mitochondria. In vivo, we found that excessive exercise could cause oxidative stress statue which led to morphological and functional changes of mitochondria. The changes, including imbalance between mitochondria fusion-fission processes, activation of mitophagy, and decrease of PGC-1α expression, could be restored by APS. We further confirmed in vitro, and what is more, we found that APS may ameliorate mitochondrial dysfunction through Sirt1 pathway. Based on the results, we may figure out part of the molecular mechanism of mitochondrial amelioration by APS.

Nitric oxide and mitochondria in metabolic syndrome

PubMed Central

Litvinova, Larisa; Atochin, Dmitriy N.; Fattakhov, Nikolai; Vasilenko, Mariia; Zatolokin, Pavel; Kirienkova, Elena

2015-01-01

Metabolic syndrome (MS) is a cluster of metabolic disorders that collectively increase the risk of cardiovascular disease. Nitric oxide (NO) plays a crucial role in the pathogeneses of MS components and is involved in different mitochondrial signaling pathways that control respiration and apoptosis. The present review summarizes the recent information regarding the interrelations of mitochondria and NO in MS. Changes in the activities of different NO synthase isoforms lead to the formation of metabolic disorders and therefore are highlighted here. Reduced endothelial NOS activity and NO bioavailability, as the main factors underlying the endothelial dysfunction that occurs in MS, are discussed in this review in relation to mitochondrial dysfunction. We also focus on potential therapeutic strategies involving NO signaling pathways that can be used to treat patients with metabolic disorders associated with mitochondrial dysfunction. The article may help researchers develop new approaches for the diagnosis, prevention and treatment of MS. PMID:25741283

Thyroid hormone-induced oxidative stress.

PubMed

Venditti, P; Di Meo, S

2006-02-01

Hypermetabolic state in hyperthyroidism is associated with tissue oxidative injury. Available data indicate that hyperthyroid tissues exhibit an increased ROS and RNS production. The increased mitochondrial ROS generation is a side effect of the enhanced level of electron carriers, by which hyperthyroid tissues increase their metabolic capacity. Investigations of antioxidant defence system have returned controversial results. Moreover, other thyroid hormone-linked biochemical changes increase tissue susceptibility to oxidative challenge, which exacerbates the injury and dysfunction they suffer under stressful conditions. Mitochondria, as a primary target for oxidative stress, might account for hyperthyroidism linked tissue dysfunction. This is consistent with the inverse relationship found between functional recovery of ischemic hyperthyroid hearts and mitochondrial oxidative damage and respiration impairment. However, thyroid hormone-activated mitochondrial mechanisms provide protection against excessive tissue dysfunction, including increased expression of uncoupling proteins, proteolytic enzymes and transcriptional coactivator PGC-1, and stimulate opening of permeability transition pores.

Nickel Inhibits Mitochondrial Fatty Acid Oxidation

PubMed Central

Uppala, Radha; McKinney, Richard W.; Brant, Kelly A.; Fabisiak, James P.; Goetzman, Eric S.

2015-01-01

Nickel exposure is associated with changes in cellular energy metabolism which may contribute to its carcinogenic properties. Here, we demonstrate that nickel strongly represses mitochondrial fatty acid oxidation—the pathway by which fatty acids are catabolized for energy—in both primary human lung fibroblasts and mouse embryonic fibroblasts. At the concentrations used, nickel suppresses fatty acid oxidation without globally suppressing mitochondrial function as evidenced by increased glucose oxidation to CO2. Pre-treatment with L-carnitine, previously shown to prevent nickel-induced mitochondrial dysfunction in neuroblastoma cells, did not prevent the inhibition of fatty acid oxidation. The effect of nickel on fatty acid oxidation occurred only with prolonged exposure (>5 hr), suggesting that direct inhibition of the active sites of metabolic enzymes is not the mechanism of action. Nickel is a known hypoxia-mimetic that activates hypoxia inducible factor-1α (HIF1α). Nickel-induced inhibition of fatty acid oxidation was blunted in HIF1α knockout fibroblasts, implicating HIF1α as one contributor to the mechanism. Additionally, nickel down-regulated the protein levels of the key fatty acid oxidation enzyme very long-chain acyl-CoA dehydrogenase (VLCAD) in a dose-dependent fashion. In conclusion, inhibition of fatty acid oxidation by nickel, concurrent with increased glucose metabolism, represents a form of metabolic reprogramming that may contribute to nickel-induced carcinogenesis. PMID:26051273

Profiling of the Tox21 Chemical Collection for Mitochondrial ...

EPA Pesticide Factsheets

Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding how different environmental chemicals and drug-like molecules impact mitochondrial function represents an initial step in predicting exposure-related toxic effects and defining a possible role for such compounds in the onset of various diseases. OBJECTIVES: To identify individual chemicals and general structural features associated with the disruption of mitochondrial membrane potential (MMP). METHODS: We used a multiplexed quantitative high throughput screening (qHTS) approach combined with informatics tools to screen the Tox21 10,000 compound library (~8300 unique chemicals) at 15 concentrations in triplicate to identify chemicals and structural features that are associated with changes in MMP in HepG2 cells. RESULTS: In the primary screening, approximately 11% of the compounds (913 unique compounds) decreased the MMP after 1 h of treatment without affecting cell viability. Additionally, 309 compounds decreased MMP over a concentration range that also produced measurable cytotoxicity [half maximal inhibitory concentration (IC50) in MMP assay/IC50 in viability assay) ≤ 3, p<0.05]. Over 11% of the structural clusters that constitute the Tox21 library (76 of 651 clusters) were significantly enriched for compounds that decreased the MMP. CONCLUSIONS: Our multiplexed qHTS approach

White Matter Lipids as a Ketogenic Fuel Supply in Aging Female Brain: Implications for Alzheimer's Disease.

PubMed

Klosinski, Lauren P; Yao, Jia; Yin, Fei; Fonteh, Alfred N; Harrington, Michael G; Christensen, Trace A; Trushina, Eugenia; Brinton, Roberta Diaz

2015-12-01

White matter degeneration is a pathological hallmark of neurodegenerative diseases including Alzheimer's. Age remains the greatest risk factor for Alzheimer's and the prevalence of age-related late onset Alzheimer's is greatest in females. We investigated mechanisms underlying white matter degeneration in an animal model consistent with the sex at greatest Alzheimer's risk. Results of these analyses demonstrated decline in mitochondrial respiration, increased mitochondrial hydrogen peroxide production and cytosolic-phospholipase-A2 sphingomyelinase pathway activation during female brain aging. Electron microscopic and lipidomic analyses confirmed myelin degeneration. An increase in fatty acids and mitochondrial fatty acid metabolism machinery was coincident with a rise in brain ketone bodies and decline in plasma ketone bodies. This mechanistic pathway and its chronologically phased activation, links mitochondrial dysfunction early in aging with later age development of white matter degeneration. The catabolism of myelin lipids to generate ketone bodies can be viewed as a systems level adaptive response to address brain fuel and energy demand. Elucidation of the initiating factors and the mechanistic pathway leading to white matter catabolism in the aging female brain provides potential therapeutic targets to prevent and treat demyelinating diseases such as Alzheimer's and multiple sclerosis. Targeting stages of disease and associated mechanisms will be critical.

White Matter Lipids as a Ketogenic Fuel Supply in Aging Female Brain: Implications for Alzheimer's Disease

PubMed Central

Klosinski, Lauren P.; Yao, Jia; Yin, Fei; Fonteh, Alfred N.; Harrington, Michael G.; Christensen, Trace A.; Trushina, Eugenia; Brinton, Roberta Diaz

2015-01-01

White matter degeneration is a pathological hallmark of neurodegenerative diseases including Alzheimer's. Age remains the greatest risk factor for Alzheimer's and the prevalence of age-related late onset Alzheimer's is greatest in females. We investigated mechanisms underlying white matter degeneration in an animal model consistent with the sex at greatest Alzheimer's risk. Results of these analyses demonstrated decline in mitochondrial respiration, increased mitochondrial hydrogen peroxide production and cytosolic-phospholipase-A2 sphingomyelinase pathway activation during female brain aging. Electron microscopic and lipidomic analyses confirmed myelin degeneration. An increase in fatty acids and mitochondrial fatty acid metabolism machinery was coincident with a rise in brain ketone bodies and decline in plasma ketone bodies. This mechanistic pathway and its chronologically phased activation, links mitochondrial dysfunction early in aging with later age development of white matter degeneration. The catabolism of myelin lipids to generate ketone bodies can be viewed as a systems level adaptive response to address brain fuel and energy demand. Elucidation of the initiating factors and the mechanistic pathway leading to white matter catabolism in the aging female brain provides potential therapeutic targets to prevent and treat demyelinating diseases such as Alzheimer's and multiple sclerosis. Targeting stages of disease and associated mechanisms will be critical. PMID:26844268

Targeted Expression of Catalase to Mitochondria Protects Against Ischemic Myopathy in High-Fat Diet–Fed Mice

PubMed Central

Ryan, Terence E.; Schmidt, Cameron A.; Green, Thomas D.; Spangenburg, Espen E.; Neufer, P. Darrell

2016-01-01

Patients with type 2 diabetes respond poorly to treatments for peripheral arterial disease (PAD) and are more likely to present with the most severe manifestation of the disease, critical limb ischemia. The underlying mechanisms linking type 2 diabetes and the severity of PAD manifestation are not well understood. We sought to test whether diet-induced mitochondrial dysfunction and oxidative stress would increase the susceptibility of the peripheral limb to hindlimb ischemia (HLI). Six weeks of high-fat diet (HFD) in C57BL/6 mice was insufficient to alter skeletal muscle mitochondrial content and respiratory function or the size of ischemic lesion after HLI, despite reducing blood flow. However, 16 weeks of HFD similarly decreased ischemic limb blood flow, but also exacerbated limb tissue necrosis, increased the myopathic lesion size, reduced muscle regeneration, attenuated muscle function, and exacerbated ischemic mitochondrial dysfunction. Mechanistically, mitochondrial-targeted overexpression of catalase prevented the HFD-induced ischemic limb necrosis, myopathy, and mitochondrial dysfunction, despite no improvement in limb blood flow. These findings demonstrate that skeletal muscle mitochondria are a critical pathological link between type 2 diabetes and PAD. Furthermore, therapeutically targeting mitochondria and oxidant burden is an effective strategy to alleviate tissue loss and ischemic myopathy during PAD. PMID:27284110

Mitochondrial Dysfunction in Retinal Diseases

PubMed Central

Barot, Megha; Gokulgandhi, Mitan R.; Mitra, Ashim K.

2015-01-01

The mitochondrion is a vital intracellular organelle for retinal cell function and survival. There is growing confirmation to support an association between mitochondrial dysfunction and a number of retinal degenerations. Investigations have also unveiled mitochondrial genomic instability as one of the contributing factors for age-related retinal pathophysiology. This review highlights the role of mitochondrial dysfunction originating from oxidative stress in the etiology of retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration (AMD). Moreover, mitochondrial DNA (mtDNA) damage associated with AMD due to susceptibility of mtDNA to oxidative damage and failure of mtDNA repair pathways is also highlighted in this review. The susceptibility of neural retina and retinal pigment epithelium (RPE) mitochondria to oxidative damage with ageing appears to be a major factor in retinal degeneration. It thus appears that the mitochondrion is a weak link in the antioxidant defenses of retinal cells. In addition, failure of mtDNA repair pathways can also specifically contribute towards pathogenesis of AMD. This review will further summarize the prospective role of mitochondria targeting therapeutic agents for the treatment of retinal disease. Mitochondria based drug targeting to diminish oxidative stress or promote repair of mtDNA damage may offer potential alternatives for the treatment of various retinal degenerative diseases. PMID:21978133

Mitochondrial dysfunction in retinal diseases.

PubMed

Barot, Megha; Gokulgandhi, Mitan R; Mitra, Ashim K

2011-12-01

The mitochondrion is a vital intracellular organelle for retinal cell function and survival. There is growing confirmation to support an association between mitochondrial dysfunction and a number of retinal degenerations. Investigations have also unveiled mitochondrial genomic instability as one of the contributing factors for age-related retinal pathophysiology. This review highlights the role of mitochondrial dysfunction originating from oxidative stress in the etiology of retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration (AMD). Moreover, mitochondrial DNA (mtDNA) damage associated with AMD due to susceptibility of mtDNA to oxidative damage and failure of mtDNA repair pathways is also highlighted in this review. The susceptibility of neural retina and retinal pigment epithelium (RPE) mitochondria to oxidative damage with ageing appears to be a major factor in retinal degeneration. It thus appears that the mitochondrion is a weak link in the antioxidant defenses of retinal cells. In addition, failure of mtDNA repair pathways can also specifically contribute towards pathogenesis of AMD. This review will further summarize the prospective role of mitochondria targeting therapeutic agents for the treatment of retinal disease. Mitochondria based drug targeting to diminish oxidative stress or promote repair of mtDNA damage may offer potential alternatives for the treatment of various retinal degenerative diseases.

Capybara Oil Improves Hepatic Mitochondrial Dysfunction, Steatosis, and Inflammation in a Murine Model of Nonalcoholic Fatty Liver Disease.

PubMed

Marinho, Polyana C; Vieira, Aline B; Pereira, Priscila G; Rabelo, Kíssila; Ciambarella, Bianca T; Nascimento, Ana L R; Cortez, Erika; Moura, Aníbal S; Guimarães, Fernanda V; Martins, Marco A; Barquero, Gonzalo; Ferreira, Rodrigo N; de Carvalho, Jorge J

2018-01-01

Nonalcoholic fatty liver disease (NAFLD) is recognized as the most common cause of liver dysfunction worldwide and is commonly associated with obesity. Evidences suggest that NAFLD might be a mitochondrial disease, which contributes to the hepatic steatosis, oxidative stress, cytokine release, and cell death. Capybara oil (CO) is a rich source of polyunsaturated fatty acids (PUFA), which is known to improve inflammation and oxidative stress. In order to determine the effects of CO on NAFLD, C57Bl/6 mice were divided into 3 groups and fed a high-fat diet (HFD) (NAFLD group and NAFLD + CO group) or a control diet (CG group) during 16 weeks. The CO (1.5 g/kg/daily) was administered by gavage during the last 4 weeks of the diet protocol. We evaluated plasma liver enzymes, hepatic steatosis, and cytokine expression in liver as well as hepatocyte ultrastructural morphology and mitochondrial function. CO treatment suppressed hepatic steatosis, attenuated inflammatory response, and decreased plasma alanine aminotransferase (ALT) in mice with NAFLD. CO was also capable of restoring mitochondrial ultrastructure and function as well as balance superoxide dismutase and catalase levels. Our findings indicate that CO treatment has positive effects on NAFLD improving mitochondrial dysfunction, steatosis, acute inflammation, and oxidative stress.

Neuroprotective effect of asiatic acid on rotenone-induced mitochondrial dysfunction and oxidative stress-mediated apoptosis in differentiated SH-SYS5Y cells.

PubMed

Nataraj, Jagatheesan; Manivasagam, Thamilarasan; Justin Thenmozhi, Arokiasamy; Essa, Musthafa Mohamed

2017-07-01

Parkinson's disease (PD) is a chronic neurodegenerative disease, manifested due to the loss of dopaminergic neurons, which ultimately leads to impaired movement in elderly populations. The pathogenesis of PD is associated with numerous factors including oxidative stress, mitochondrial dysfunction and apoptosis. There is no effective therapy available to cure or halt the progression of this disease still now. Asiatic acid (AA) is a triterpene extracted from Centella asiatica has been reported as an antioxidant and anti-inflammatory agent, that offers neuroprotection against glutamate toxicity. Therefore, in this study, we have investigated the effect of AA in a rotenone (an inhibitor of mitochondrial complex I) induced in vitro model of PD. Following the exposure of SH-SY5Y cells to rotenone, there was a marked overproduction of ROS, mitochondrial dysfunction (as indexed by the decrease in mitochondrial membrane potential) and apoptosis (Hoechst and dual staining, comet assay; expressions of pro-apoptotic and anti-apoptotic indices). Pre-treatment with AA reversed these changes might be due to its antioxidant, mitoprotective and anti-apoptotic properties. However further extensive studies on in vivo models of PD are warranted to prove AA neuroprotective effect before entering into the clinical trial.

Vascular rarefaction mediates whitening of brown fat in obesity

PubMed Central

Shimizu, Ippei; Aprahamian, Tamar; Kikuchi, Ryosuke; Shimizu, Ayako; Papanicolaou, Kyriakos N.; MacLauchlan, Susan; Maruyama, Sonomi; Walsh, Kenneth

2014-01-01

Brown adipose tissue (BAT) is a highly vascularized organ with abundant mitochondria that produce heat through uncoupled respiration. Obesity is associated with a reduction of BAT function; however, it is unknown how obesity promotes dysfunctional BAT. Here, using a murine model of diet-induced obesity, we determined that obesity causes capillary rarefaction and functional hypoxia in BAT, leading to a BAT “whitening” phenotype that is characterized by mitochondrial dysfunction, lipid droplet accumulation, and decreased expression of Vegfa. Targeted deletion of Vegfa in adipose tissue of nonobese mice resulted in BAT whitening, supporting a role for decreased vascularity in obesity-associated BAT. Conversely, introduction of VEGF-A specifically into BAT of obese mice restored vascularity, ameliorated brown adipocyte dysfunction, and improved insulin sensitivity. The capillary rarefaction in BAT that was brought about by obesity or Vegfa ablation diminished β-adrenergic signaling, increased mitochondrial ROS production, and promoted mitophagy. These data indicate that overnutrition leads to the development of a hypoxic state in BAT, causing it to whiten through mitochondrial dysfunction and loss. Furthermore, these results link obesity-associated BAT whitening to impaired systemic glucose metabolism. PMID:24713652

PINK1 deficiency impairs mitochondrial homeostasis and promotes lung fibrosis

PubMed Central

Bueno, Marta; Lai, Yen-Chun; Romero, Yair; Brands, Judith; St. Croix, Claudette M.; Kamga, Christelle; Corey, Catherine; Herazo-Maya, Jose D.; Sembrat, John; Lee, Janet S.; Duncan, Steve R.; Rojas, Mauricio; Shiva, Sruti; Chu, Charleen T.; Mora, Ana L.

2014-01-01

Although aging is a known risk factor for idiopathic pulmonary fibrosis (IPF), the pathogenic mechanisms that underlie the effects of advancing age remain largely unexplained. Some age-related neurodegenerative diseases have an etiology that is related to mitochondrial dysfunction. Here, we found that alveolar type II cells (AECIIs) in the lungs of IPF patients exhibit marked accumulation of dysmorphic and dysfunctional mitochondria. These mitochondrial abnormalities in AECIIs of IPF lungs were associated with upregulation of ER stress markers and were recapitulated in normal mice with advancing age in response to stimulation of ER stress. We found that impaired mitochondria in IPF and aging lungs were associated with low expression of PTEN-induced putative kinase 1 (PINK1). Knockdown of PINK1 expression in lung epithelial cells resulted in mitochondria depolarization and expression of profibrotic factors. Moreover, young PINK1-deficient mice developed similarly dysmorphic, dysfunctional mitochondria in the AECIIs and were vulnerable to apoptosis and development of lung fibrosis. Our data indicate that PINK1 deficiency results in swollen, dysfunctional mitochondria and defective mitophagy, and promotes fibrosis in the aging lung. PMID:25562319

Ex Vivo Cardiotoxicity of Antineoplastic Casiopeinas Is Mediated through Energetic Dysfunction and Triggered Mitochondrial-Dependent Apoptosis.

PubMed

Silva-Platas, Christian; Villegas, César A; Oropeza-Almazán, Yuriana; Carrancá, Mariana; Torres-Quintanilla, Alejandro; Lozano, Omar; Valero-Elizondo, Javier; Castillo, Elena C; Bernal-Ramírez, Judith; Fernández-Sada, Evaristo; Vega, Luis F; Treviño-Saldaña, Niria; Chapoy-Villanueva, Héctor; Ruiz-Azuara, Lena; Hernández-Brenes, Carmen; Elizondo-Montemayor, Leticia; Guerrero-Beltrán, Carlos E; Carvajal, Karla; Bravo-Gómez, María E; García-Rivas, Gerardo

2018-01-01

Casiopeinas are a group of copper-based antineoplastic molecules designed as a less toxic and more therapeutic alternative to cisplatin or Doxorubicin; however, there is scarce evidence about their toxic effects on the whole heart and cardiomyocytes. Given this, rat hearts were perfused with Casiopeinas or Doxorubicin and the effects on mechanical performance, energetics, and mitochondrial function were measured. As well, the effects of Casiopeinas-triggered cell death were explored in isolated cardiomyocytes. Casiopeinas III-Ea, II-gly, and III-ia induced a progressive and sustained inhibition of heart contractile function that was dose- and time-dependent with an IC 50 of 1.3 ± 0.2, 5.5 ± 0.5, and 10 ± 0.7  μ M, correspondingly. Myocardial oxygen consumption was not modified at their respective IC 50 , although ATP levels were significantly reduced, indicating energy impairment. Isolated mitochondria from Casiopeinas-treated hearts showed a significant loss of membrane potential and reduction of mitochondrial Ca 2+ retention capacity. Interestingly, Cyclosporine A inhibited Casiopeinas-induced mitochondrial Ca 2+ release, which suggests the involvement of the mitochondrial permeability transition pore opening. In addition, Casiopeinas reduced the viability of cardiomyocytes and stimulated the activation of caspases 3, 7, and 9, demonstrating a cell death mitochondrial-dependent mechanism. Finally, the early perfusion of Cyclosporine A in isolated hearts decreased Casiopeinas-induced dysfunction with reduction of their toxic effect. Our results suggest that heart cardiotoxicity of Casiopeinas is similar to that of Doxorubicin, involving heart mitochondrial dysfunction, loss of membrane potential, changes in energetic metabolites, and apoptosis triggered by mitochondrial permeability.

Aldehydic load and aldehyde dehydrogenase 2 profile during the progression of post-myocardial infarction cardiomyopathy: benefits of Alda-1

PubMed Central

Gomes, Katia M.S.; Bechara, Luiz R.G.; Lima, Vanessa M.; Ribeiro, Márcio A.C.; Campos, Juliane C.; Dourado, Paulo M.; Kowaltowski, Alicia J.; Mochly-Rosen, Daria; Ferreira, Julio C.B.

2015-01-01

Background/Objectives We previously demonstrated that reducing cardiac aldehydic load by aldehyde dehydrogenase 2 (ALDH2), a mitochondrial enzyme responsible for metabolizing the major lipid peroxidation product, protects against acute ischemia/reperfusion injury and chronic heart failure. However, time-dependent changes in ALDH2 profile, aldehydic load and mitochondrial bioenergetics during progression of post-myocardial infarction (post-MI) cardiomyopathy is unknown and should be established to determine the optimal time window for drug treatment. Methods Here we characterized cardiac ALDH2 activity and expression, lipid peroxidation, 4-hydroxy-2-nonenal (4-HNE) adduct formation, glutathione pool and mitochondrial energy metabolism and H2O2 release during the 4 weeks after permanent left anterior descending (LAD) coronary artery occlusion in rats. Results We observed a sustained disruption of cardiac mitochondrial function during the progression of post-MI cardiomyopathy, characterized by >50% reduced mitochondrial respiratory control ratios and up to 2 fold increase in H2O2 release. Mitochondrial dysfunction was accompanied by accumulation of cardiac and circulating lipid peroxides and 4-HNE protein adducts and down-regulation of electron transport chain complexes I and V. Moreover, increased aldehydic load was associated with a 90% reduction in cardiac ALDH2 activity and increased glutathione pool. Further supporting an ALDH2 mechanism, sustained Alda-1 treatment (starting 24hrs after permanent LAD occlusion surgery) prevented aldehydic overload, mitochondrial dysfunction and improved ventricular function in post-MI cardiomyopathy rats. Conclusion Taken together, our findings demonstrate a disrupted mitochondrial metabolism along with an insufficient cardiac ALDH2-mediated aldehyde clearance during the progression of ventricular dysfunction, suggesting a potential therapeutic value of ALDH2 activators during the progression of post-myocardial infarction cardiomyopathy. PMID:25464432

Ketamine Causes Mitochondrial Dysfunction in Human Induced Pluripotent Stem Cell-Derived Neurons

PubMed Central

Ito, Hiroyuki; Uchida, Tokujiro; Makita, Koshi

2015-01-01

Purpose Ketamine toxicity has been demonstrated in nonhuman mammalian neurons. To study the toxic effect of ketamine on human neurons, an experimental model of cultured neurons from human induced pluripotent stem cells (iPSCs) was examined, and the mechanism of its toxicity was investigated. Methods Human iPSC-derived dopaminergic neurons were treated with 0, 20, 100 or 500 μM ketamine for 6 and 24 h. Ketamine toxicity was evaluated by quantification of caspase 3/7 activity, reactive oxygen species (ROS) production, mitochondrial membrane potential, ATP concentration, neurotransmitter reuptake activity and NADH/NAD+ ratio. Mitochondrial morphological change was analyzed by transmission electron microscopy and confocal microscopy. Results Twenty-four-hour exposure of iPSC-derived neurons to 500 μM ketamine resulted in a 40% increase in caspase 3/7 activity (P < 0.01), 14% increase in ROS production (P < 0.01), and 81% reduction in mitochondrial membrane potential (P < 0.01), compared with untreated cells. Lower concentration of ketamine (100 μM) decreased the ATP level (22%, P < 0.01) and increased the NADH/NAD+ ratio (46%, P < 0.05) without caspase activation. Transmission electron microscopy showed enhanced mitochondrial fission and autophagocytosis at the 100 μM ketamine concentration, which suggests that mitochondrial dysfunction preceded ROS generation and caspase activation. Conclusions We established an in vitro model for assessing the neurotoxicity of ketamine in iPSC-derived neurons. The present data indicate that the initial mitochondrial dysfunction and autophagy may be related to its inhibitory effect on the mitochondrial electron transport system, which underlies ketamine-induced neural toxicity. Higher ketamine concentration can induce ROS generation and apoptosis in human neurons. PMID:26020236

Ex Vivo Cardiotoxicity of Antineoplastic Casiopeinas Is Mediated through Energetic Dysfunction and Triggered Mitochondrial-Dependent Apoptosis

PubMed Central

Silva-Platas, Christian; Villegas, César A.; Carrancá, Mariana; Lozano, Omar; Valero-Elizondo, Javier; Bernal-Ramírez, Judith; Fernández-Sada, Evaristo; Vega, Luis F.; Chapoy-Villanueva, Héctor; Ruiz-Azuara, Lena; Hernández-Brenes, Carmen; Guerrero-Beltrán, Carlos E.; Bravo-Gómez, María E.

2018-01-01

Casiopeinas are a group of copper-based antineoplastic molecules designed as a less toxic and more therapeutic alternative to cisplatin or Doxorubicin; however, there is scarce evidence about their toxic effects on the whole heart and cardiomyocytes. Given this, rat hearts were perfused with Casiopeinas or Doxorubicin and the effects on mechanical performance, energetics, and mitochondrial function were measured. As well, the effects of Casiopeinas-triggered cell death were explored in isolated cardiomyocytes. Casiopeinas III-Ea, II-gly, and III-ia induced a progressive and sustained inhibition of heart contractile function that was dose- and time-dependent with an IC50 of 1.3 ± 0.2, 5.5 ± 0.5, and 10 ± 0.7 μM, correspondingly. Myocardial oxygen consumption was not modified at their respective IC50, although ATP levels were significantly reduced, indicating energy impairment. Isolated mitochondria from Casiopeinas-treated hearts showed a significant loss of membrane potential and reduction of mitochondrial Ca2+ retention capacity. Interestingly, Cyclosporine A inhibited Casiopeinas-induced mitochondrial Ca2+ release, which suggests the involvement of the mitochondrial permeability transition pore opening. In addition, Casiopeinas reduced the viability of cardiomyocytes and stimulated the activation of caspases 3, 7, and 9, demonstrating a cell death mitochondrial-dependent mechanism. Finally, the early perfusion of Cyclosporine A in isolated hearts decreased Casiopeinas-induced dysfunction with reduction of their toxic effect. Our results suggest that heart cardiotoxicity of Casiopeinas is similar to that of Doxorubicin, involving heart mitochondrial dysfunction, loss of membrane potential, changes in energetic metabolites, and apoptosis triggered by mitochondrial permeability. PMID:29765507

Curcumin Rescues a PINK1 Knock Down SH-SY5Y Cellular Model of Parkinson's Disease from Mitochondrial Dysfunction and Cell Death.

PubMed

van der Merwe, Celia; van Dyk, Hayley Christy; Engelbrecht, Lize; van der Westhuizen, Francois Hendrikus; Kinnear, Craig; Loos, Ben; Bardien, Soraya

2017-05-01

Parkinson's disease (PD) is a neurodegenerative disorder characterised by the loss of dopaminergic neurons in the substantia nigra. Mutations in the PINK1 gene result in an autosomal recessive form of early-onset PD. PINK1 plays a vital role in mitochondrial quality control via the removal of dysfunctional mitochondria. The aim of the present study was to create a cellular model of PD using siRNA-mediated knock down of PINK1 in SH-SY5Y neuroblastoma cells The possible protective effects of curcumin, known for its many beneficial properties including antioxidant and anti-inflammatory effects, was tested on this model in the presence and absence of paraquat, an additional stressor. PINK1 siRNA and control cells were separated into four treatment groups: (i) untreated, (ii) treated with paraquat, (iii) pre-treated with curcumin then treated with paraquat, or (iv) treated with curcumin. Various parameters of cellular and mitochondrial function were then measured. The PINK1 siRNA cells exhibited significantly decreased cell viability, mitochondrial membrane potential (MMP), mitochondrial respiration and ATP production, and increased apoptosis. Paraquat-treated cells exhibited decreased cell viability, increased apoptosis, a more fragmented mitochondrial network and decreased MMP. Curcumin pre-treatment followed by paraquat exposure rescued cell viability and increased MMP and mitochondrial respiration in control cells, and significantly decreased apoptosis and increased MMP and maximal respiration in PINK1 siRNA cells. These results highlight a protective effect of curcumin against mitochondrial dysfunction and apoptosis in PINK1-deficient and paraquat-exposed cells. More studies are warranted to further elucidate the potential neuroprotective properties of curcumin.

Sophora flavescens Aiton Decreases MPP+-Induced Mitochondrial Dysfunction in SH-SY5Y Cells

PubMed Central

Kim, Hee-Young; Jeon, Hyongjun; Kim, Hyungwoo; Koo, Sungtae; Kim, Seungtae

2018-01-01

Sophora flavescens Aiton (SF) has been used to treat various diseases including fever and inflammation in China, South Korea and Japan. Several recent reports have shown that SF has anti-inflammatory and anti-apoptotic effects, indicating that it is a promising candidate for treatment of Parkinson’s disease (PD). We evaluated the protective effect of SF against neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+)-induced mitochondrial dysfunction in SH-SY5Y human neuroblastoma cells, an in vitro PD model. SH-SY5Y cells were incubated with SF for 24 h, after which they were treated with MPP+. MPP+-induced cytotoxicity and apoptosis were confirmed by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling assay. MitoSOX red mitochondrial superoxide indicator, tetramethylrhodamine methyl ester perchlorate and Parkin, PTEN-induced putative kinase 1 (PINK1), and DJ-1 immunofluorescent staining were conducted to confirm the mitochondrial function. In addition, western blot was performed to evaluate apoptosis factors (Bcl-2, Bax, caspase-3 and cytochrome c) and mitochondrial function-related factors (Parkin, PINK1 and DJ-1). SF suppressed MPP+-induced cytotoxicity, apoptosis and collapse of mitochondrial membrane potential by inhibiting the increase of reactive oxidative species (ROS) and DNA fragmentation, and controlling Bcl-2, Bax, caspase-3 and cytochrome c expression. Moreover, it attenuated Parkin, PINK1 and DJ-1 expression from MPP+-induced decrease. SF effectively suppressed MPP+-induced cytotoxicity, apoptosis and mitochondrial dysfunction by regulating generation of ROS, disruption of mitochondrial membrane potential, mitochondria-dependent apoptosis and loss or mutation of mitochondria-related PD markers including Parkin, PINK1 and DJ-1. PMID:29740311

Sophora flavescens Aiton Decreases MPP+-Induced Mitochondrial Dysfunction in SH-SY5Y Cells.

PubMed

Kim, Hee-Young; Jeon, Hyongjun; Kim, Hyungwoo; Koo, Sungtae; Kim, Seungtae

2018-01-01

Sophora flavescens Aiton (SF) has been used to treat various diseases including fever and inflammation in China, South Korea and Japan. Several recent reports have shown that SF has anti-inflammatory and anti-apoptotic effects, indicating that it is a promising candidate for treatment of Parkinson's disease (PD). We evaluated the protective effect of SF against neurotoxin 1-methyl-4-phenylpyridinium ion (MPP + )-induced mitochondrial dysfunction in SH-SY5Y human neuroblastoma cells, an in vitro PD model. SH-SY5Y cells were incubated with SF for 24 h, after which they were treated with MPP + . MPP + -induced cytotoxicity and apoptosis were confirmed by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling assay. MitoSOX red mitochondrial superoxide indicator, tetramethylrhodamine methyl ester perchlorate and Parkin, PTEN-induced putative kinase 1 (PINK1), and DJ-1 immunofluorescent staining were conducted to confirm the mitochondrial function. In addition, western blot was performed to evaluate apoptosis factors (Bcl-2, Bax, caspase-3 and cytochrome c) and mitochondrial function-related factors (Parkin, PINK1 and DJ-1). SF suppressed MPP + -induced cytotoxicity, apoptosis and collapse of mitochondrial membrane potential by inhibiting the increase of reactive oxidative species (ROS) and DNA fragmentation, and controlling Bcl-2, Bax, caspase-3 and cytochrome c expression. Moreover, it attenuated Parkin, PINK1 and DJ-1 expression from MPP + -induced decrease. SF effectively suppressed MPP + -induced cytotoxicity, apoptosis and mitochondrial dysfunction by regulating generation of ROS, disruption of mitochondrial membrane potential, mitochondria-dependent apoptosis and loss or mutation of mitochondria-related PD markers including Parkin, PINK1 and DJ-1.

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.

Resveratrol attenuates methylglyoxal-induced mitochondrial dysfunction and apoptosis by Sestrin2 induction

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

Seo, Kyuhwa; Seo, Suho; Han, Jae Yun

2014-10-15

Methylglyoxal is found in high levels in the blood and other tissues of diabetic patients and exerts deleterious effects on cells and tissues. Previously, we reported that resveratrol, a polyphenol in grapes, induced the expression of Sestrin2 (SESN2), a novel antioxidant protein, and inhibited hepatic lipogenesis. This study investigated whether resveratrol protects cells from the methylglyoxal-induced toxicity via SESN2 induction. Methylglyoxal significantly induced cell death in HepG2 cells. However, cells pretreated with resveratrol were rescued from methylglyoxal-induced apoptosis. Resveratrol attenuated glutathione (GSH) depletion and ROS production promoted by methylglyoxal. Moreover, mitochondrial damage was observed by methylglyoxal treatment, but resveratrol restoredmore » mitochondrial function, as evidenced by the observed lack of mitochondrial permeability transition and increased ADP/ATP ratio. Resveratrol treatment inhibited SESN2 depletion elicited by methylglyoxal. SESN2 overexpression repressed methylglyoxal-induced mitochondrial dysfunction and apoptosis. Likewise, rotenone-induced cytotoxicity was not observed in SESN2 overexpressed cells. Furthermore, siRNA knockdown of SESN2 reduced the ability of resveratrol to prevent methylglyoxal-induced mitochondrial permeability transition. In addition, when mice were exposed to methylglyoxal after infection of Ad-SESN2, the plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and GSH depletion by methylglyoxal in liver was reduced in Ad-SESN2 infected mice. Our results demonstrated that resveratrol is capable of protecting cells from methylglyoxal-induced mitochondrial dysfunction and oxidative stress via SESN2 induction. - Highlights: • Resveratrol decreased methylglyoxal-induced apoptosis. • Resveratrol attenuated GSH depletion and ROS production promoted by methylglyoxal. • Resveratrol restored the mitochondrial function by Sestrin2 induction. • Induction of Sestrin2 prevented methylglyoxal-induced GSH depletion in liver.« less

Marine Cyanobacteria Compounds with Anticancer Properties: A Review on the Implication of Apoptosis

PubMed Central

Costa, Margarida; Costa-Rodrigues, João; Fernandes, Maria Helena; Barros, Piedade; Vasconcelos, Vitor; Martins, Rosário

2012-01-01

Marine cyanobacteria have been considered a rich source of secondary metabolites with potential biotechnological applications, namely in the pharmacological field. Chemically diverse compounds were found to induce cytoxicity, anti-inflammatory and antibacterial activities. The potential of marine cyanobacteria as anticancer agents has however been the most explored and, besides cytotoxicity in tumor cell lines, several compounds have emerged as templates for the development of new anticancer drugs. The mechanisms implicated in the cytotoxicity of marine cyanobacteria compounds in tumor cell lines are still largely overlooked but several studies point to an implication in apoptosis. This association has been related to several apoptotic indicators such as cell cycle arrest, mitochondrial dysfunctions and oxidative damage, alterations in caspase cascade, alterations in specific proteins levels and alterations in the membrane sodium dynamics. In the present paper a compilation of the described marine cyanobacterial compounds with potential anticancer properties is presented and a review on the implication of apoptosis as the mechanism of cell death is discussed. PMID:23170077

Syndromes associated with mitochondrial DNA depletion

PubMed Central

2014-01-01

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

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

PubMed

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

2013-01-01

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

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

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

PubMed Central

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

2013-01-01

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

Ptpmt1 induced by HIF-2α regulates the proliferation and glucose metabolism in erythroleukemia cells

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

Xu, Qin-Qin; Qinghai Provincial People's Hospital, Xining; Xiao, Feng-Jun

Hypoxia provokes metabolism misbalance, mitochondrial dysfunction and oxidative stress in both human and animal cells. However, the mechanisms which hypoxia causes mitochondrial dysfunction and energy metabolism misbalance still remain unclear. In this study, we presented evidence that mitochondrial phosphatase Ptpmt1 is a hypoxia response molecule that regulates cell proliferation, survival and glucose metabolism in human erythroleukemia TF-1 cells. Exposure to hypoxia or DFO treatment results in upregulation of HIF1-α, HIF-2α and Ptpmt1. Only inhibition of HIF-2α by shRNA transduction reduces Ptpmt1 expression in TF-1 cells under hypoxia. Ptpmt1 inhibitor suppresses the growth and induces apoptosis of TF-1 cells. Furthermore, we demonstrated that Ptpmt1more » inhibition reduces the Glut1 and Glut3 expression and decreases the glucose consumption in TF-1 cells. In additional, Ptpmt1 knockdown also results in the mitochondrial dysfunction determined by JC1 staining. These results delineate a key role for HIF-2α-induced Ptpmt1 upregulation in proliferation, survival and glucose metabolism of erythroleukemia cells. It is indicated that Ptpmt1 plays important roles in hypoxia-induced cell metabolism and mitochondrial dysfunction. - Highlights: • Hypoxia induces upregulation of HIF-1α, HIF-2α and Ptpmt1; HIF-2a induces Ptpmt1 upregulation in TF-1 cells. • PTPMT-1 inhibition reduces growth and induces apoptosis of TF-1 cells. • PTPMT1 inhibition downregulates Glut-1, Glut-3 expression and reduces glucose consumption.« less

Role of mitochondrial DNA damage and dysfunction in veterans with Gulf War Illness.

PubMed

Chen, Yang; Meyer, Joel N; Hill, Helene Z; Lange, Gudrun; Condon, Michael R; Klein, Jacquelyn C; Ndirangu, Duncan; Falvo, Michael J

2017-01-01

Gulf War Illness (GWI) is a chronic multi-symptom illness not currently diagnosed by standard medical or laboratory test that affects 30% of veterans who served during the 1990-1991 Gulf War. The clinical presentation of GWI is comparable to that of patients with certain mitochondrial disorders-i.e., clinically heterogeneous multisystem symptoms. Therefore, we hypothesized that mitochondrial dysfunction may contribute to both the symptoms of GWI as well as its persistence over time. We recruited 21 cases of GWI (CDC and Kansas criteria) and 7 controls to participate in this study. Peripheral blood samples were obtained in all participants and a quantitative polymerase chain reaction (QPCR) based assay was performed to quantify mitochondrial and nuclear DNA lesion frequency and mitochondrial DNA (mtDNA) copy number (mtDNAcn) from peripheral blood mononuclear cells. Samples were also used to analyze nuclear DNA lesion frequency and enzyme activity for mitochondrial complexes I and IV. Both mtDNA lesion frequency (p = 0.015, d = 1.13) and mtDNAcn (p = 0.001; d = 1.69) were elevated in veterans with GWI relative to controls. Nuclear DNA lesion frequency was also elevated in veterans with GWI (p = 0.344; d = 1.41), but did not reach statistical significance. Complex I and IV activity (p > 0.05) were similar between groups and greater mtDNA lesion frequency was associated with reduced complex I (r2 = -0.35, p = 0.007) and IV (r2 = -0.28, p < 0.01) enzyme activity. In conclusion, veterans with GWI exhibit greater mtDNA damage which is consistent with mitochondrial dysfunction.

Metabolic flexibility of mitochondrial respiratory chain disorders predicted by computer modelling.

PubMed

Zieliński, Łukasz P; Smith, Anthony C; Smith, Alexander G; Robinson, Alan J

2016-11-01

Mitochondrial respiratory chain dysfunction causes a variety of life-threatening diseases affecting about 1 in 4300 adults. These diseases are genetically heterogeneous, but have the same outcome; reduced activity of mitochondrial respiratory chain complexes causing decreased ATP production and potentially toxic accumulation of metabolites. Severity and tissue specificity of these effects varies between patients by unknown mechanisms and treatment options are limited. So far most research has focused on the complexes themselves, and the impact on overall cellular metabolism is largely unclear. To illustrate how computer modelling can be used to better understand the potential impact of these disorders and inspire new research directions and treatments, we simulated them using a computer model of human cardiomyocyte mitochondrial metabolism containing over 300 characterised reactions and transport steps with experimental parameters taken from the literature. Overall, simulations were consistent with patient symptoms, supporting their biological and medical significance. These simulations predicted: complex I deficiencies could be compensated using multiple pathways; complex II deficiencies had less metabolic flexibility due to impacting both the TCA cycle and the respiratory chain; and complex III and IV deficiencies caused greatest decreases in ATP production with metabolic consequences that parallel hypoxia. Our study demonstrates how results from computer models can be compared to a clinical phenotype and used as a tool for hypothesis generation for subsequent experimental testing. These simulations can enhance understanding of dysfunctional mitochondrial metabolism and suggest new avenues for research into treatment of mitochondrial disease and other areas of mitochondrial dysfunction. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Neuronal Lipid Metabolism: Multiple Pathways Driving Functional Outcomes in Health and Disease

PubMed Central

Tracey, Timothy J.; Steyn, Frederik J.; Wolvetang, Ernst J.; Ngo, Shyuan T.

2018-01-01

Lipids are a fundamental class of organic molecules implicated in a wide range of biological processes related to their structural diversity, and based on this can be broadly classified into five categories; fatty acids, triacylglycerols (TAGs), phospholipids, sterol lipids and sphingolipids. Different lipid classes play major roles in neuronal cell populations; they can be used as energy substrates, act as building blocks for cellular structural machinery, serve as bioactive molecules, or a combination of each. In amyotrophic lateral sclerosis (ALS), dysfunctions in lipid metabolism and function have been identified as potential drivers of pathogenesis. In particular, aberrant lipid metabolism is proposed to underlie denervation of neuromuscular junctions, mitochondrial dysfunction, excitotoxicity, impaired neuronal transport, cytoskeletal defects, inflammation and reduced neurotransmitter release. Here we review current knowledge of the roles of lipid metabolism and function in the CNS and discuss how modulating these pathways may offer novel therapeutic options for treating ALS. PMID:29410613

High-fat diet induces cardiac remodelling and dysfunction: assessment of the role played by SIRT3 loss.

PubMed

Zeng, Heng; Vaka, Venkata Ramana; He, Xiaochen; Booz, George W; Chen, Jian-Xiong

2015-08-01

Mitochondrial dysfunction plays an important role in obesity-induced cardiac impairment. SIRT3 is a mitochondrial protein associated with increased human life span and metabolism. This study investigated the functional role of SIRT3 in obesity-induced cardiac dysfunction. Wild-type (WT) and SIRT3 knockout (KO) mice were fed a normal diet (ND) or high-fat diet (HFD) for 16 weeks. Body weight, fasting glucose levels, reactive oxygen species (ROS) levels, myocardial capillary density, cardiac function and expression of hypoxia-inducible factor (HIF)-1α/-2α were assessed. HFD resulted in a significant reduction in SIRT3 expression in the heart. Both HFD and SIRT3 KO mice showed increased ROS formation, impaired HIF signalling and reduced capillary density in the heart. HFD induced cardiac hypertrophy and impaired cardiac function. SIRT3 KO mice fed HFD showed greater ROS production and a further reduction in cardiac function compared to SIRT3 KO mice on ND. Thus, the adverse effects of HFD on cardiac function were not attributable to SIRT3 loss alone. However, HFD did not further reduce capillary density in SIRT3 KO hearts, implicating SIRT3 loss in HFD-induced capillary rarefaction. Our study demonstrates the importance of SIRT3 in preserving heart function and capillary density in the setting of obesity. Thus, SIRT3 may be a potential therapeutic target for obesity-induced heart failure. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Hyperglycemia induced damage to mitochondrial respiration in renal mesangial and tubular cells: Implications for diabetic nephropathy.

PubMed

Czajka, Anna; Malik, Afshan N

2016-12-01

Damage to renal tubular and mesangial cells is central to the development of diabetic nephropathy (DN), a complication of diabetes which can lead to renal failure. Mitochondria are the site of cellular respiration and produce energy in the form of ATP via oxidative phosphorylation, and mitochondrial dysfunction has been implicated in DN. Since the kidney is an organ with high bioenergetic needs, we postulated that hyperglycemia causes damage to renal mitochondria resulting in bioenergetic deficit. The bioenergetic profiles and the effect of hyperglycemia on cellular respiration of human primary mesangial (HMCs) and proximal tubular cells (HK-2) were compared in normoglycemic and hyperglycemic conditions using the seahorse bio-analyzer. In normoglycemia, HK-2 had significantly lower basal, ATP-linked and maximal respiration rates, and lower reserve capacity compared to HMCs. Hyperglycemia caused a down-regulation of all respiratory parameters within 4 days in HK-2 but not in HMCs. After 8 days of hyperglycemia, down-regulation of respiratory parameters persisted in tubular cells with compensatory up-regulated glycolysis. HMCs had reduced maximal respiration and reserve capacity at 8 days, and by 12 days had compromised mitochondrial respiration despite which they did not enhance glycolysis. These data suggest that diabetes is likely to lead to a cellular deficit in ATP production in both cell types, although with different sensitivities, and this mechanism could significantly contribute to the cellular damage seen in the diabetic kidney. Prevention of diabetes induced damage to renal mitochondrial respiration may be a novel therapeutic approach for the prevention/treatment of DN. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Indomethacin, a non-steroidal anti-inflammatory drug, develops gastropathy by inducing reactive oxygen species-mediated mitochondrial pathology and associated apoptosis in gastric mucosa: a novel role of mitochondrial aconitase oxidation.

PubMed

Maity, Pallab; Bindu, Samik; Dey, Sumanta; Goyal, Manish; Alam, Athar; Pal, Chinmay; Mitra, Kalyan; Bandyopadhyay, Uday

2009-01-30

We have investigated the role of mitochondria on the development of indomethacin (a non-steroidal anti-inflammatory drug)-induced gastric mucosal apoptosis and associated gastropathy in rat. Transmission electron microscopic studies indicate that indomethacin damages mitochondrial ultrastructure and causes mitochondrial dysfunction as evident from decreased stage-3 respiration, dehydrogenase activity, and transmembrane potential (DeltaPsi(m)). Mitochondrial pathology is associated with increased generation of intra-mitochondrial-reactive oxygen species, such as O(2)(*), H(2)O(2) and *OH, leading to oxidative stress. O(2)(*) is the most effective to damage mitochondrial aconitase, leading to the release of iron from its iron-sulfur cluster. The released iron, by interacting with intra-mitochondrial H(2)O(2), forms *OH. Immunoprecipitation of mitochondrial aconitase and subsequent Western immunoblotting indicate carbonylation of aconitase along with the loss of activity in vivo after indomethacin treatment. The release of iron has been documented by fluorescence imaging of mucosal cells by using Phen Green SK, a specific probe for chelatable iron. Interestingly, intra-mitochondrial *OH generation is crucial for the development of mitochondrial pathology and activation of mitochondrial death pathway by indomethacin. Scavenging of *OH by dimethyl sulfoxide or alpha-phenyl-n-tert-butylnitrone, a spin-trap, prevents indomethacin-induced mitochondrial ultrastructural changes, oxidative stress, collapse of DeltaPsi(m), and mitochondrial dysfunction. The scavengers also restore indomethacin-induced activation of caspase-9 and caspase-3 to block mitochondrial pathway of apoptosis and gastric mucosal damage. This study, thus, reveals the critical role of O(2)(*)-mediated mitochondrial aconitase inactivation to release intra-mitochondrial iron, which by generating *OH promotes gastric mucosal cell apoptosis and gastropathy during indomethacin treatment.

PPAR-γ Regulates Carnitine Homeostasis and Mitochondrial Function in a Lamb Model of Increased Pulmonary Blood Flow

PubMed Central

Rafikov, Ruslan; Kumar, Sanjiv; Hou, Yali; Oishi, Peter E.; Datar, Sanjeev A.; Raff, Gary; Fineman, Jeffrey R.; Black, Stephen M.

2012-01-01

Objective Carnitine homeostasis is disrupted in lambs with endothelial dysfunction secondary to increased pulmonary blood flow (Shunt). Our recent studies have also indicated that the disruption in carnitine homeostasis correlates with a decrease in PPAR-γ expression in Shunt lambs. Thus, this study was carried out to determine if there is a causal link between loss of PPAR-γ signaling and carnitine dysfunction, and whether the PPAR-γ agonist, rosiglitazone preserves carnitine homeostasis in Shunt lambs. Methods and Results siRNA-mediated PPAR-γ knockdown significantly reduced carnitine palmitoyltransferases 1 and 2 (CPT1 and 2) and carnitine acetyltransferase (CrAT) protein levels. This decrease in carnitine regulatory proteins resulted in a disruption in carnitine homeostasis and induced mitochondrial dysfunction, as determined by a reduction in cellular ATP levels. In turn, the decrease in cellular ATP attenuated NO signaling through a reduction in eNOS/Hsp90 interactions and enhanced eNOS uncoupling. In vivo, rosiglitazone treatment preserved carnitine homeostasis and attenuated the development of mitochondrial dysfunction in Shunt lambs maintaining ATP levels. This in turn preserved eNOS/Hsp90 interactions and NO signaling. Conclusion Our study indicates that PPAR-γ signaling plays an important role in maintaining mitochondrial function through the regulation of carnitine homeostasis both in vitro and in vivo. Further, it identifies a new mechanism by which PPAR-γ regulates NO signaling through Hsp90. Thus, PPAR-γ agonists may have therapeutic potential in preventing the endothelial dysfunction in children with increased pulmonary blood flow. PMID:22962578

Increased Ventricular Cerebrospinal Fluid Lactate in Depressed Adolescents

PubMed Central

Bradley, Kailyn A. L.; Mao, Xiangling; Case, Julia A. C.; Kang, Guoxin; Shungu, Dikoma C.; Gabbay, Vilma

2016-01-01

Background Mitochondrial dysfunction has been increasingly examined as a potential pathogenic event in psychiatric disorders, although its role early in the course of major depressive disorder (MDD) is unclear. Therefore, the purpose of this study was to investigate mitochondrial dysfunction in medication-free adolescents with MDD through in vivo measurements of neurometabolites using high-spatial resolution multislice/multivoxel proton magnetic resonance spectroscopy. Methods Twenty-three adolescents with MDD and 29 healthy controls, ages 12–20, were scanned at 3T and concentrations of ventricular cerebrospinal fluid lactate, as well as N-acetyl-aspartate (NAA), total creatine (tCr), and total choline (tCho) in the bilateral caudate, putamen, and thalamus were reported. Results Adolescents with MDD exhibited increased ventricular lactate compared to healthy controls [F(1, 41) = 6.98, p = .01]. However, there were no group differences in the other neurometabolites. Dimensional analyses in the depressed group showed no relation between any of the neurometabolites and symptomatology, including anhedonia and fatigue. Conclusions Increased ventricular lactate in depressed adolescents suggests mitochondrial dysfunction may be present early in the course of MDD; however it is still not known whether the presence of mitochondrial dysfunction is a trait vulnerability of individuals predisposed to psychopathology or a state feature of the disorder. Therefore, there is a need for larger multimodal studies to clarify these chemical findings in the context of network function. PMID:26802978

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

PubMed

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

2014-10-01

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

Hyperammonaemia‐induced skeletal muscle mitochondrial dysfunction results in cataplerosis and oxidative stress

PubMed Central

Davuluri, Gangarao; Allawy, Allawy; Thapaliya, Samjhana; Rennison, Julie H.; Singh, Dharmvir; Kumar, Avinash; Sandlers, Yana; Van Wagoner, David R.; Flask, Chris A.; Hoppel, Charles; Kasumov, Takhar

2016-01-01

Key points Hyperammonaemia occurs in hepatic, cardiac and pulmonary diseases with increased muscle concentration of ammonia.We found that ammonia results in reduced skeletal muscle mitochondrial respiration, electron transport chain complex I dysfunction, as well as lower NAD+/NADH ratio and ATP content.During hyperammonaemia, leak of electrons from complex III results in oxidative modification of proteins and lipids.Tricarboxylic acid cycle intermediates are decreased during hyperammonaemia, and providing a cell‐permeable ester of αKG reversed the lower TCA cycle intermediate concentrations and increased ATP content.Our observations have high clinical relevance given the potential for novel approaches to reverse skeletal muscle ammonia toxicity by targeting the TCA cycle intermediates and mitochondrial ROS. Abstract Ammonia is a cytotoxic metabolite that is removed primarily by hepatic ureagenesis in humans. Hyperammonaemia occurs in advanced hepatic, cardiac and pulmonary disease, and in urea cycle enzyme deficiencies. Increased skeletal muscle ammonia uptake and metabolism are the major mechanism of non‐hepatic ammonia disposal. Non‐hepatic ammonia disposal occurs in the mitochondria via glutamate synthesis from α‐ketoglutarate resulting in cataplerosis. We show skeletal muscle mitochondrial dysfunction during hyperammonaemia in a comprehensive array of human, rodent and cellular models. ATP synthesis, oxygen consumption, generation of reactive oxygen species with oxidative stress, and tricarboxylic acid (TCA) cycle intermediates were quantified. ATP content was lower in the skeletal muscle from cirrhotic patients, hyperammonaemic portacaval anastomosis rat, and C2C12 myotubes compared to appropriate controls. Hyperammonaemia in C2C12 myotubes resulted in impaired intact cell respiration, reduced complex I/NADH oxidase activity and electron leak occurring at complex III of the electron transport chain. Consistently, lower NAD+/NADH ratio was observed during hyperammonaemia with reduced TCA cycle intermediates compared to controls. Generation of reactive oxygen species resulted in increased content of skeletal muscle carbonylated proteins and thiobarbituric acid reactive substances during hyperammonaemia. A cell‐permeable ester of α‐ketoglutarate reversed the low TCA cycle intermediates and ATP content in myotubes during hyperammonaemia. However, the mitochondrial antioxidant MitoTEMPO did not reverse the lower ATP content during hyperammonaemia. We provide for the first time evidence that skeletal muscle hyperammonaemia results in mitochondrial dysfunction and oxidative stress. Use of anaplerotic substrates to reverse ammonia‐induced mitochondrial dysfunction is a novel therapeutic approach. PMID:27558544

Identification of Genes Potentially Regulated by Human Polynucleotide Phosphorylase (hPNPaseold-35) Using Melanoma as a Model

PubMed Central

Sokhi, Upneet K.; Bacolod, Manny D.; Dasgupta, Santanu; Emdad, Luni; Das, Swadesh K.; Dumur, Catherine I.; Miles, Michael F.; Sarkar, Devanand; Fisher, Paul B.

2013-01-01

Human Polynucleotide Phosphorylase (hPNPaseold-35 or PNPT1) is an evolutionarily conserved 3′→5′ exoribonuclease implicated in the regulation of numerous physiological processes including maintenance of mitochondrial homeostasis, mtRNA import and aging-associated inflammation. From an RNase perspective, little is known about the RNA or miRNA species it targets for degradation or whose expression it regulates; except for c-myc and miR-221. To further elucidate the functional implications of hPNPaseold-35 in cellular physiology, we knocked-down and overexpressed hPNPaseold-35 in human melanoma cells and performed gene expression analyses to identify differentially expressed transcripts. Ingenuity Pathway Analysis indicated that knockdown of hPNPaseold-35 resulted in significant gene expression changes associated with mitochondrial dysfunction and cholesterol biosynthesis; whereas overexpression of hPNPaseold-35 caused global changes in cell-cycle related functions. Additionally, comparative gene expression analyses between our hPNPaseold-35 knockdown and overexpression datasets allowed us to identify 77 potential “direct” and 61 potential “indirect” targets of hPNPaseold-35 which formed correlated networks enriched for cell-cycle and wound healing functional association, respectively. These results provide a comprehensive database of genes responsive to hPNPaseold-35 expression levels; along with the identification new potential candidate genes offering fresh insight into cellular pathways regulated by PNPT1 and which may be used in the future for possible therapeutic intervention in mitochondrial- or inflammation-associated disease phenotypes. PMID:24143183

CR108, a novel vitamin K3 derivative induces apoptosis and breast tumor inhibition by reactive oxygen species and mitochondrial dysfunction

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

Yang, Chun-Ru; Liao, Wei-Siang; Wu, Ya-Hui

Vitamin K3 derivatives have been shown to exert anticancer activities. Here we show a novel vitamin K3 derivative (S)-2-(2-hydroxy-3-methylbutylthio)naphthalene-1,4-dione, which is named as CR108 that induces apoptosis and tumor inhibition through reactive oxygen species (ROS) and mitochondrial dysfunction in human breast cancer. CR108 is more effective on the breast cancer cell death than other vitamin K3 derivatives. Moreover, CR108 induced apoptosis in both the non-HER-2-overexpressed MCF-7 and HER-2-overexpressed BT-474 breast cancer cells. CR108 caused the loss of mitochondrial membrane potential, cytochrome c released from mitochondria to cytosol, and cleaved PARP proteins for apoptosis induction. CR108 markedly increased ROS levels inmore » breast cancer cells. N-acetylcysteine (NAC), a general ROS scavenger, completely blocked the CR108-induced ROS levels, mitochondrial dysfunction and apoptosis. Interestingly, CR108 increased the phosphorylation of p38 MAP kinase but conversely inhibited the survivin protein expression. NAC treatment prevented the activation of p38 MAP kinase and rescued the survivin protein levels. SB202190, a specific p38 MAP kinase inhibitor, recovered the survivin protein levels and attenuated the cytotoxicity of CR108-treated cells. Furthermore, CR108 inhibited the xenografted human breast tumor growth in nude mice. Together, we demonstrate that CR108 is a novel vitamin K3 derivative that induces apoptosis and tumor inhibition by ROS production and mitochondrial dysfunction and associates with the phosphorylation of p38 MAP kinase and the inhibition of survivin in the human breast cancer. - Highlights: • CR108 is more effective on the cell death than other vitamin K3 derivatives. • CR108 induces apoptosis and tumor inhibition by ROS and mitochondrial dysfunction. • CR108 induces apoptosis by p38 kinase activation and survivin inhibition. • CR108 is a potent vitamin K3 analog that can develop for breast cancer therapy.« less

Naringin ameliorates gentamicin-induced nephrotoxicity and associated mitochondrial dysfunction, apoptosis and inflammation in rats: Possible mechanism of nephroprotection

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

Sahu, Bidya Dhar; Tatireddy, Srujana; Koneru, Meghana

Gentamicin-induced nephrotoxicity has been well documented, although its underlying mechanisms and preventive strategies remain to be investigated. The present study was designed to investigate the protective effect of naringin, a bioflavonoid, on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific renal function parameters (blood urea nitrogen and creatinine) and histopathology of kidney tissues were evaluated to assess the gentamicin-induced nephrotoxicity. Renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic and non-enzymatic antioxidants), inflammatory (NF-kB [p65], TNF-α, IL-6 and MPO) and apoptotic (caspase 3, caspase 9, Bax, Bcl-2, p53 and DNA fragmentation) markers were also evaluated. Significant decrease in mitochondrialmore » NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity indicated the gentamicin-induced mitochondrial dysfunction. Naringin (100 mg/kg) treatment along with gentamicin restored the mitochondrial function and increased the renal endogenous antioxidant status. Gentamicin induced increased renal inflammatory cytokines (TNF-α and IL-6), nuclear protein expression of NF-κB (p65) and NF-κB-DNA binding activity and myeloperoxidase (MPO) activity were significantly decreased upon naringin treatment. In addition, naringin treatment significantly decreased the amount of cleaved caspase 3, Bax, and p53 protein expression and increased the Bcl-2 protein expression. Naringin treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. U-HPLS-MS data revealed that naringin co-administration along with gentamicin did not alter the renal uptake and/or accumulation of gentamicin in kidney tissues. These findings suggest that naringin treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, mitochondrial dysfunction, inflammation and apoptosis in the kidney. - Highlights: • Naringin ameliorated gentamicin-induced nephrotoxicity in rats. • Naringin treatment attenuated gentamicin-induced renal apoptosis in rats. • Naringin ameliorated gentamicin-induced renal mitochondrial dysfunction in rats. • Naringin decreased NF-κB activation and pro-inflammatory cytokine release. • U-HPLC-MS data revealed that naringin did not alter the renal uptake of gentamicin.« less

Discovery of non-peptidic small molecule inhibitors of cyclophilin D as neuroprotective agents in Aβ-induced mitochondrial dysfunction

NASA Astrophysics Data System (ADS)

Park, Insun; Londhe, Ashwini M.; Lim, Ji Woong; Park, Beoung-Geon; Jung, Seo Yun; Lee, Jae Yeol; Lim, Sang Min; No, Kyoung Tai; Lee, Jiyoun; Pae, Ae Nim

2017-10-01

Cyclophilin D (CypD) is a mitochondria-specific cyclophilin that is known to play a pivotal role in the formation of the mitochondrial permeability transition pore (mPTP).The formation and opening of the mPTP disrupt mitochondrial homeostasis, cause mitochondrial dysfunction and eventually lead to cell death. Several recent studies have found that CypD promotes the formation of the mPTP upon binding to β amyloid (Aβ) peptides inside brain mitochondria, suggesting that neuronal CypD has a potential to be a promising therapeutic target for Alzheimer's disease (AD). In this study, we generated an energy-based pharmacophore model by using the crystal structure of CypD—cyclosporine A (CsA) complex and performed virtual screening of ChemDiv database, which yielded forty-five potential hit compounds with novel scaffolds. We further tested those compounds using mitochondrial functional assays in neuronal cells and identified fifteen compounds with excellent protective effects against Aβ-induced mitochondrial dysfunction. To validate whether these effects derived from binding to CypD, we performed surface plasmon resonance (SPR)—based direct binding assays with selected compounds and discovered compound 29 was found to have the equilibrium dissociation constants (KD) value of 88.2 nM. This binding affinity value and biological activity correspond well with our predicted binding mode. We believe that this study offers new insights into the rational design of small molecule CypD inhibitors, and provides a promising lead for future therapeutic development.

Enhancing fatty acid utilization ameliorates mitochondrial fragmentation and cardiac dysfunction via rebalancing optic atrophy 1 processing in the failing heart.

PubMed

Guo, Yongzheng; Wang, Zhen; Qin, Xinghua; Xu, Jie; Hou, Zuoxu; Yang, Hongyan; Mao, Xuechao; Xing, Wenjuan; Li, Xiaoliang; Zhang, Xing; Gao, Feng

2018-06-01

Heart failure (HF) is characterized by reduced fatty acid (FA) utilization associated with mitochondrial dysfunction. Recent evidence has shown that enhancing FA utilization may provide cardioprotection against HF. Our aim was to investigate the effects and the underlying mechanisms of cardiac FA utilization on cardiac function in response to pressure overload. Transverse aortic constriction (TAC) was used in C57 mice to establish pressure overload-induced HF. TAC mice fed on a high fat diet (HFD) exhibited increased cardiac FA utilization and improved cardiac function and survival compared with those on control diet. Such cardioprotection could also be provided by cardiac-specific overexpression of CD36. Notably, both HFD and CD36 overexpression attenuated mitochondrial fragmentation and improved mitochondrial function in the failing heart. Pressure overload decreased ATP-dependent metalloprotease (YME1L) expression and induced the proteolytic cleavage of the dynamin-like guanosine triphosphatase OPA1 as a result of suppressed FA utilization. Enhancing FA utilization upregulated YME1L expression and subsequently rebalanced OPA1 processing, resulting in restoration of mitochondrial morphology in the failing heart. In addition, cardiac-specific overexpression of YME1L exerted similar cardioprotective effects against HF to those provided by HFD or CD36 overexpression. These findings demonstrate that enhancing FA utilization ameliorates mitochondrial fragmentation and cardiac dysfunction via rebalancing OPA1 processing in pressure overload-induced HF, suggesting a unique metabolic intervention approach to improving cardiac functions in HF.

Mito-Apocynin Prevents Mitochondrial Dysfunction, Microglial Activation, Oxidative Damage, and Progressive Neurodegeneration in MitoPark Transgenic Mice.

PubMed

Langley, Monica; Ghosh, Anamitra; Charli, Adhithiya; Sarkar, Souvarish; Ay, Muhammet; Luo, Jie; Zielonka, Jacek; Brenza, Timothy; Bennett, Brian; Jin, Huajun; Ghaisas, Shivani; Schlichtmann, Benjamin; Kim, Dongsuk; Anantharam, Vellareddy; Kanthasamy, Arthi; Narasimhan, Balaji; Kalyanaraman, Balaraman; Kanthasamy, Anumantha G

2017-11-10

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive motor deficits and degeneration of dopaminergic neurons. Caused by a number of genetic and environmental factors, mitochondrial dysfunction and oxidative stress play a role in neurodegeneration in PD. By selectively knocking out mitochondrial transcription factor A (TFAM) in dopaminergic neurons, the transgenic MitoPark mice recapitulate many signature features of the disease, including progressive motor deficits, neuronal loss, and protein inclusions. In the present study, we evaluated the neuroprotective efficacy of a novel mitochondrially targeted antioxidant, Mito-apocynin, in MitoPark mice and cell culture models of neuroinflammation and mitochondrial dysfunction. Oral administration of Mito-apocynin (10 mg/kg, thrice a week) showed excellent central nervous system bioavailability and significantly improved locomotor activity and coordination in MitoPark mice. Importantly, Mito-apocynin also partially attenuated severe nigrostriatal degeneration in MitoPark mice. Mechanistic studies revealed that Mito-apo improves mitochondrial function and inhibits NOX2 activation, oxidative damage, and neuroinflammation. The properties of Mito-apocynin identified in the MitoPark transgenic mouse model strongly support potential clinical applications for Mito-apocynin as a viable neuroprotective and anti-neuroinflammatory drug for treating PD when compared to conventional therapeutic approaches. Collectively, our data demonstrate, for the first time, that a novel orally active apocynin derivative improves behavioral, inflammatory, and neurodegenerative processes in a severe progressive dopaminergic neurodegenerative model of PD. Antioxid. Redox Signal. 27, 1048-1066.

Common presentation of rare diseases: Left ventricular hypertrophy and diastolic dysfunction.

PubMed

Linhart, Ales; Cecchi, Franco

2018-04-15

Left ventricular hypertrophy may be a consequence of a hemodynamic overload or a manifestation of several diseases affecting different structural and functional proteins of cardiomyocytes. Among these, sarcomeric hypertrophic cardiomyopathy (HCM) represents the most frequent cause. In addition, several metabolic diseases lead to myocardial thickening, either due to intracellular storage (glycogen storage and lysosomal diseases), extracellular deposition (TTR and AL amyloidosis) or due to abnormal energy metabolism (mitochondrial diseases). The recognition of these rare causes of myocardial hypertrophy is important for family screening strategies, risk assessment, and treatment. Moreover, as there are specific therapies for some forms of HCM including enzyme substitution and chaperone therapies and specific treatments for TTR amyloidosis, a differential diagnosis should be sought in all patients with unexplained left ventricular hypertrophy. Diastolic dysfunction is a key feature of HCM and its phenocopies. Its assessment is complex and requires evaluation of several functional parameters and structural changes. Severe diastolic dysfunction carries a negative prognostic implication and its value in differential diagnosis is limited. Copyright © 2018 Elsevier B.V. All rights reserved.

O-GlcNAcase deficiency suppresses skeletal myogenesis and insulin sensitivity in mice through the modulation of mitochondrial homeostasis.

PubMed

Wang, Xun; Feng, Zhihui; Wang, Xueqiang; Yang, Liang; Han, Shujun; Cao, Ke; Xu, Jie; Zhao, Lin; Zhang, Yong; Liu, Jiankang

2016-06-01

O-GlcNAcylation is implicated in modulating mitochondrial function, which is closely involved in regulating muscle metabolism. The presence of O-GlcNAcase (OGA), the enzyme involved in the removal of O-GlcNAc, in mitochondria was recently confirmed in rats. In the present study, we investigated the regulation of myogenesis and muscle insulin sensitivity to OGA in mice, with a focus on mitochondria. C57BL/6J mice fed a high-fat diet for 4 months were used to observe mitochondrial density, activity and O-GlcNAcylation in muscle. Small interfering RNA and overexpression vectors were used to modulate protein content in vitro. High-fat feeding decreased the OGA level and largely increased mitochondrial O-GlcNAcylation in mouse skeletal muscle that was accompanied by decreased levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), decreased mitochondrial density and disrupted mitochondrial complex activities. Knockdown of OGA in C2C12 myoblasts promoted PGC-1α degradation, resulting in the suppression of mitochondrial biogenesis and myogenesis, whereas neither knockdown of O-GlcNAc transferase nor overexpression of OGA had significant effects on myogenesis. Mitochondrial dysfunction as evidenced by decreased ATP content and increased reactive oxygen species production, and increased lipid and protein oxidation was observed in both myoblasts and myotubes after OGA knockdown. Meanwhile, elevated O-GlcNAcylation through either OGA knockdown or treatment with the OGA inhibitor PUGNAc and the O-GlcNAc transferase substrate D-GlcNAc suppressed myotube insulin signalling transduction and glucose uptake. OGA overexpression had no significant effect on insulin sensitivity but sufficiently improved the insulin resistance induced by D-GlcNAc treatment. These data suggest that OGA can modulate mitochondrial density via PGC-1α and mitochondrial function via protein O-GlcNAcylation. In this manner, OGA appears to play a key role in myogenesis and the development of muscle insulin resistance.

Insulin Resistance and Alzheimer's Disease: Bioenergetic Linkages.

PubMed

Neth, Bryan J; Craft, Suzanne

2017-01-01

Metabolic dysfunction is a well-established feature of Alzheimer's disease (AD), evidenced by brain glucose hypometabolism that can be observed potentially decades prior to the development of AD symptoms. Furthermore, there is mounting support for an association between metabolic disease and the development of AD and related dementias. Individuals with insulin resistance, type 2 diabetes mellitus (T2D), hyperlipidemia, obesity, or other metabolic disease may have increased risk for the development of AD and similar conditions, such as vascular dementia. This association may in part be due to the systemic mitochondrial dysfunction that is common to these pathologies. Accumulating evidence suggests that mitochondrial dysfunction is a significant feature of AD and may play a fundamental role in its pathogenesis. In fact, aging itself presents a unique challenge due to inherent mitochondrial dysfunction and prevalence of chronic metabolic disease. Despite the progress made in understanding the pathogenesis of AD and in the development of potential therapies, at present we remain without a disease-modifying treatment. In this review, we will discuss insulin resistance as a contributing factor to the pathogenesis of AD, as well as the metabolic and bioenergetic disruptions linking insulin resistance and AD. We will also focus on potential neuroimaging tools for the study of the metabolic dysfunction commonly seen in AD with hopes of developing therapeutic and preventative targets.

Naringin Improves Diet-Induced Cardiovascular Dysfunction and Obesity in High Carbohydrate, High Fat Diet-Fed Rats

PubMed Central

Alam, Md. Ashraful; Kauter, Kathleen; Brown, Lindsay

2013-01-01

Obesity, insulin resistance, hypertension and fatty liver, together termed metabolic syndrome, are key risk factors for cardiovascular disease. Chronic feeding of a diet high in saturated fats and simple sugars, such as fructose and glucose, induces these changes in rats. Naturally occurring compounds could be a cost-effective intervention to reverse these changes. Flavonoids are ubiquitous secondary plant metabolites; naringin gives the bitter taste to grapefruit. This study has evaluated the effect of naringin on diet-induced obesity and cardiovascular dysfunction in high carbohydrate, high fat-fed rats. These rats developed increased body weight, glucose intolerance, increased plasma lipid concentrations, hypertension, left ventricular hypertrophy and fibrosis, liver inflammation and steatosis with compromised mitochondrial respiratory chain activity. Dietary supplementation with naringin (approximately 100 mg/kg/day) improved glucose intolerance and liver mitochondrial dysfunction, lowered plasma lipid concentrations and improved the structure and function of the heart and liver without decreasing total body weight. Naringin normalised systolic blood pressure and improved vascular dysfunction and ventricular diastolic dysfunction in high carbohydrate, high fat-fed rats. These beneficial effects of naringin may be mediated by reduced inflammatory cell infiltration, reduced oxidative stress, lowered plasma lipid concentrations and improved liver mitochondrial function in rats. PMID:23446977

Genetics of Mitochondrial Disease.

PubMed

Saneto, Russell P

2017-01-01

Mitochondria are intracellular organelles responsible for adenosine triphosphate production. The strict control of intracellular energy needs require proper mitochondrial functioning. The mitochondria are under dual controls of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). Mitochondrial dysfunction can arise from changes in either mtDNA or nDNA genes regulating function. There are an estimated ∼1500 proteins in the mitoproteome, whereas the mtDNA genome has 37 proteins. There are, to date, ∼275 genes shown to give rise to disease. The unique physiology of mitochondrial functioning contributes to diverse gene expression. The onset and range of phenotypic expression of disease is diverse, with onset from neonatal to seventh decade of life. The range of dysfunction is heterogeneous, ranging from single organ to multisystem involvement. The complexity of disease expression has severely limited gene discovery. Combining phenotypes with improvements in gene sequencing strategies are improving the diagnosis process. This chapter focuses on the interplay of the unique physiology and gene discovery in the current knowledge of genetically derived mitochondrial disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Oxidized mitochondrial DNA activates the NLRP3 inflammasome during apoptosis.

PubMed

Shimada, Kenichi; Crother, Timothy R; Karlin, Justin; Dagvadorj, Jargalsaikhan; Chiba, Norika; Chen, Shuang; Ramanujan, V Krishnan; Wolf, Andrea J; Vergnes, Laurent; Ojcius, David M; Rentsendorj, Altan; Vargas, Mario; Guerrero, Candace; Wang, Yinsheng; Fitzgerald, Katherine A; Underhill, David M; Town, Terrence; Arditi, Moshe

2012-03-23

We report that in the presence of signal 1 (NF-κB), the NLRP3 inflammasome was activated by mitochondrial apoptotic signaling that licensed production of interleukin-1β (IL-1β). NLRP3 secondary signal activators such as ATP induced mitochondrial dysfunction and apoptosis, resulting in release of oxidized mitochondrial DNA (mtDNA) into the cytosol, where it bound to and activated the NLRP3 inflammasome. The antiapoptotic protein Bcl-2 inversely regulated mitochondrial dysfunction and NLRP3 inflammasome activation. Mitochondrial DNA directly induced NLRP3 inflammasome activation, because macrophages lacking mtDNA had severely attenuated IL-1β production, yet still underwent apoptosis. Both binding of oxidized mtDNA to the NLRP3 inflammasome and IL-1β secretion could be competitively inhibited by the oxidized nucleoside 8-OH-dG. Thus, our data reveal that oxidized mtDNA released during programmed cell death causes activation of the NLRP3 inflammasome. These results provide a missing link between apoptosis and inflammasome activation, via binding of cytosolic oxidized mtDNA to the NLRP3 inflammasome. Copyright © 2012 Elsevier Inc. All rights reserved.

Oxidized Mitochondrial DNA Activates the NLRP3 Inflammasome During Apoptosis

PubMed Central

Shimada, Kenichi; Crother, Timothy R.; Karlin, Justin; Dagvadorj, Jargalsaikhan; Chiba, Norika; Chen, Shuang; Ramanujan, V. Krishnan; Wolf, Andrea J.; Vergnes, Laurent; Ojcius, David M.; Rentsendorj, Altan; Vargas, Mario; Guerrero, Candace; Wang, Yinsheng; Fitzgerald, Katherine A.; Underhill, David M.; Town, Terrence; Arditi, Moshe

2012-01-01

SUMMARY We report that in the presence of signal 1 (NF-κB), the NLRP3 inflammasome was activated by mitochondrial apoptotic signaling that licensed production of interleukin-1β (IL-1β). NLRP3 secondary signal activators such as ATP induced mitochondrial dysfunction and apoptosis, resulting in release of oxidized mitochondrial DNA (mtDNA) into the cytosol, where it bound to and activated the NLRP3 inflammasome. The anti-apoptotic protein Bcl-2 inversely regulated mitochondrial dysfunction and NLRP3 inflammasome activation. Mitochondrial DNA directly induced NLRP3 inflammasome activation, because macrophages lacking mtDNA had severely attenuated IL-1β production, yet still underwent apoptosis. Both binding of oxidized mtDNA to the NLRP3 inflammasome and IL-1β secretion could be competitively inhibited by the oxidized nucleoside, 8-OH-dG. Thus, our data reveal that oxidized mtDNA released during programmed cell death causes activation of the NLRP3 inflammasome. These results provide a missing link between apoptosis and inflammasome activation, via binding of cytosolic oxidized mtDNA to the NLRP3 inflammasome. PMID:22342844

Recombinant Buckwheat Trypsin Inhibitor Induces Mitophagy by Directly Targeting Mitochondria and Causes Mitochondrial Dysfunction in Hep G2 Cells.

PubMed

Wang, Zhuanhua; Li, Shanshan; Ren, Rong; Li, Jiao; Cui, Xiaodong

2015-09-09

Mitochondria are essential targets for cancer chemotherapy and other disease treatments. Recombinant buckwheat trypsin inhibitor (rBTI), a member of the potato type I proteinase inhibitor family, was derived from tartary buckwheat extracts. Our results showed that rBTI directly targeted mitochondria and induced mitochondrial fragmentation and mitophagy. This occurs through enhanced depolarization of the mitochondrial membrane potential, increasing reactive oxygen species (ROS) generation associated with the rise of the superoxide dismutase and catalase activity and glutathione peroxidase (GSH) content, and changes in the GSH/oxidized glutathione ratio. Mild and transient ROS induced by rBTI were shown to be important signaling molecules required to induce Hep G2 mitophagy to remove dysfunctional mitochondria. Furthermore, rBTI could directly induce mitochondrial fragmentation. It was also noted that rBTI highly increased colocalization of mitochondria in treated cells compared to nontreated cells. Tom 20, a subunit of the translocase of the mitochondrial outer membrane complex responsible for recognizing mitochondrial presequences, may be the direct target of rBTI.

The Cytomegalovirus protein pUL37×1 targets mitochondria to mediate neuroprotection

PubMed Central

Hong, Chien Tai; Chau, Kai-Yin; Schapira, Anthony H. V.

2016-01-01

There is substantial evidence that mitochondrial dysfunction plays a significant role in the pathogenesis of Parkinson disease (PD). This contribution probably encompasses defects of oxidative phosphorylation, mitochondrial turnover (mitophagy), mitochondrial derived oxidative stress, and apoptotic signalling. Human cytomegalovirus immediate-early protein pUL37 × 1 induces Bax mitochondrial translocation and inactivation to prevent apoptosis. Over-expressing pUL37 × 1 in neuronal cells protects against staurosporin and 6-hydroxydopamine induced apoptosis and cell death. Protection is not enhanced by bax silencing in pUL37 × 1 over-expressing cells, suggesting a bax-dependent mechanism of action. pUL37 × 1 increases glycolysis and induces mitochondrial hyperpolarization, a bax independent anti-apoptotic action. pUL37 × 1 increases glycolysis through activation of phosphofructokinase by a calcium-dependent pathway. The dual anti-apoptotic mechanism of pUL37 × 1 may be considered a novel neuroprotective strategy in diseases where mitochondrial dysfunction and apoptotic pathways are involved. PMID:27562039

Protective activities of Vaccinium antioxidants with potential relevance to mitochondrial dysfunction and neurotoxicity.

PubMed

Yao, Yu; Vieira, Amandio

2007-01-01

Both the neurotransmitter dopamine (DA) and a neurotoxic metabolite, 6-hydroxy DA, can be oxidized to generate hydrogen peroxide and other reactive species (ROS). ROS promote oxidative stress and have been implicated in dopaminergic neurodegeneration, e.g., Parkinson's disease (PD). There is also evidence for a relation between catecholamine-mediated oxidative damage in dopaminergic neurons and the effects of these neurotransmitters on the redox state of cytochrome c (Cytc). In neurons and other cells, oxidative stress may be enhanced by abnormal release of Cytc and other mitochondrial proteins into the cytoplasm. Cytc release can result in apoptosis; but sub-apoptogenic-threshold release can also occur, and may be highly damaging in the presence of DA metabolites. Loss of mitochondrial membrane integrity, a pathological situation of relevance to several aging-related neurodegenerative disorders including PD, contributes to release of Cytc; and the level of such release is known to be indicative of the extent of mitochondrial dysfunction. In this context, we have used a Cytc-enhanced 6-hydroxy DA oxidation reaction to gauge dietary antioxidant activities. Anthocyanin-rich preparations of Vaccinium species (Vaccinium myrtillus, Vaccinium corymbosum, and Vaccinium oxycoccus) as well as a purified glycosylated anthocyanidin were compared. The most potent inhibition of oxidation was observed with V. myrtillus preparation: 50% inhibition with 7 microM of total anthocyanins. This activity was 1.5-4 times higher than that for the other preparations or for the purified anthocyanin. Ascorbate (Vitamin C), at up to 4-fold higher concentrations, did not result in significant inhibition in this assay. Antioxidant activity in the assay correlated strongly (r2>0.91, P<0.01) with reported Vaccinium content of anthocyanins and total cyanidins, but not quercetin or myricetin. The results provide evidence for the high potency of anthocyanins towards a potentially neurotoxic reaction, and provide a basis for in vivo testing of these flavonoids and their physiological metabolites in the context of neuro- and mitochondrio-protective effects.

Oxidative Stress and Mitochondrial Functions in the Intestinal Caco-2/15 Cell Line

PubMed Central

Taha, Rame; Seidman, Ernest; Mailhot, Genevieve; Boudreau, François; Gendron, Fernand-Pierre; Beaulieu, Jean-François; Ménard, Daniel; Delvin, Edgard; Amre, Devendra; Levy, Emile

2010-01-01

Background Although mitochondrial dysfunction and oxidative stress are central mechanisms in various pathological conditions, they have not been extensively studied in the gastrointestinal tract, which is known to be constantly exposed to luminal oxidants from ingested foods. Key among these is the simultaneous consumption of iron salts and ascorbic acid, which can cause oxidative damage to biomolecules. Methodology/Principal Findings The objective of the present work was to evaluate how iron-ascorbate (FE/ASC)-mediated lipid peroxidation affects mitochondrion functioning in Caco-2/15 cells. Our results show that treatment of Caco-2/15 cells with FE/ASC (0.2 mM/2 mM) (1) increased malondialdehyde levels assessed by HPLC; (2) reduced ATP production noted by luminescence assay; (3) provoked dysregulation of mitochondrial calcium homeostasis as evidenced by confocal fluorescence microscopy; (4) upregulated the protein expression of cytochrome C and apoptotic inducing factor, indicating exaggerated apoptosis; (5) affected mitochondrial respiratory chain complexes I, II, III and IV; (6) elicited mtDNA lesions as illustrated by the raised levels of 8-OHdG; (7) lowered DNA glycosylase, one of the first lines of defense against 8-OHdG mutagenicity; and (8) altered the gene expression and protein mass of mitochondrial transcription factors (mtTFA, mtTFB1, mtTFB2) without any effects on RNA Polymerase. The presence of the powerful antioxidant BHT (50 µM) prevented the occurrence of oxidative stress and most of the mitochondrial abnormalities. Conclusions/Significance Collectively, our findings indicate that acute exposure of Caco-2/15 cells to FE/ASC-catalyzed peroxidation produces harmful effects on mitochondrial functions and DNA integrity, which are abrogated by the powerful exogenous BHT antioxidant. Functional derangements of mitochondria may have implications in oxidative stress-related disorders such as inflammatory bowel diseases. PMID:20676402

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

PubMed

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

2015-08-01

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

Oxidative stress and mitochondrial functions in the intestinal Caco-2/15 cell line.

PubMed

Taha, Rame; Seidman, Ernest; Mailhot, Genevieve; Boudreau, François; Gendron, Fernand-Pierre; Beaulieu, Jean-François; Ménard, Daniel; Delvin, Edgard; Amre, Devendra; Levy, Emile

2010-07-27

Although mitochondrial dysfunction and oxidative stress are central mechanisms in various pathological conditions, they have not been extensively studied in the gastrointestinal tract, which is known to be constantly exposed to luminal oxidants from ingested foods. Key among these is the simultaneous consumption of iron salts and ascorbic acid, which can cause oxidative damage to biomolecules. The objective of the present work was to evaluate how iron-ascorbate (FE/ASC)-mediated lipid peroxidation affects mitochondrion functioning in Caco-2/15 cells. Our results show that treatment of Caco-2/15 cells with FE/ASC (0.2 mM/2 mM) (1) increased malondialdehyde levels assessed by HPLC; (2) reduced ATP production noted by luminescence assay; (3) provoked dysregulation of mitochondrial calcium homeostasis as evidenced by confocal fluorescence microscopy; (4) upregulated the protein expression of cytochrome C and apoptotic inducing factor, indicating exaggerated apoptosis; (5) affected mitochondrial respiratory chain complexes I, II, III and IV; (6) elicited mtDNA lesions as illustrated by the raised levels of 8-OHdG; (7) lowered DNA glycosylase, one of the first lines of defense against 8-OHdG mutagenicity; and (8) altered the gene expression and protein mass of mitochondrial transcription factors (mtTFA, mtTFB1, mtTFB2) without any effects on RNA Polymerase. The presence of the powerful antioxidant BHT (50 microM) prevented the occurrence of oxidative stress and most of the mitochondrial abnormalities. Collectively, our findings indicate that acute exposure of Caco-2/15 cells to FE/ASC-catalyzed peroxidation produces harmful effects on mitochondrial functions and DNA integrity, which are abrogated by the powerful exogenous BHT antioxidant. Functional derangements of mitochondria may have implications in oxidative stress-related disorders such as inflammatory bowel diseases.

Redox imbalance and mitochondrial abnormalities in the diabetic lung.

PubMed

Wu, Jinzi; Jin, Zhen; Yan, Liang-Jun

2017-04-01

Although the lung is one of the least studied organs in diabetes, increasing evidence indicates that it is an inevitable target of diabetic complications. Nevertheless, the underlying biochemical mechanisms of lung injury in diabetes remain largely unexplored. Given that redox imbalance, oxidative stress, and mitochondrial dysfunction have been implicated in diabetic tissue injury, we set out to investigate mechanisms of lung injury in diabetes. The objective of this study was to evaluate NADH/NAD + redox status, oxidative stress, and mitochondrial abnormalities in the diabetic lung. Using STZ induced diabetes in rat as a model, we measured redox-imbalance related parameters including aldose reductase activity, level of poly ADP ribose polymerase (PAPR-1), NAD + content, NADPH content, reduced form of glutathione (GSH), and glucose 6-phophate dehydrogenase (G6PD) activity. For assessment of mitochondrial abnormalities in the diabetic lung, we measured the activities of mitochondrial electron transport chain complexes I to IV and complex V as well as dihydrolipoamide dehydrogenase (DLDH) content and activity. We also measured the protein content of NAD + dependent enzymes such as sirtuin3 (sirt3) and NAD(P)H: quinone oxidoreductase 1 (NQO1). Our results demonstrate that NADH/NAD + redox imbalance occurs in the diabetic lung. This redox imbalance upregulates the activities of complexes I to IV, but not complex V; and this upregulation is likely the source of increased mitochondrial ROS production, oxidative stress, and cell death in the diabetic lung. These results, together with the findings that the protein contents of DLDH, sirt3, and NQO1 all are decreased in the diabetic lung, demonstrate that redox imbalance, mitochondrial abnormality, and oxidative stress contribute to lung injury in diabetes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The targeted anti-oxidant MitoQ causes mitochondrial swelling and depolarization in kidney tissue.

PubMed

Gottwald, Esther M; Duss, Michael; Bugarski, Milica; Haenni, Dominik; Schuh, Claus D; Landau, Ehud M; Hall, Andrew M

2018-04-01

Kidney proximal tubules (PTs) contain a high density of mitochondria, which are required to generate ATP to power solute transport. Mitochondrial dysfunction is implicated in the pathogenesis of numerous kidney diseases. Damaged mitochondria are thought to produce excess reactive oxygen species (ROS), which can lead to oxidative stress and activation of cell death pathways. MitoQ is a mitochondrial targeted anti-oxidant that has shown promise in preclinical models of renal diseases. However, recent studies in nonkidney cells have suggested that MitoQ might also have adverse effects. Here, using a live imaging approach, and both in vitro and ex vivo models, we show that MitoQ induces rapid swelling and depolarization of mitochondria in PT cells, but these effects were not observed with SS-31, another targeted anti-oxidant. MitoQ consists of a lipophilic cation (Tetraphenylphosphonium [TPP]) joined to an anti-oxidant component (quinone) by a 10-carbon alkyl chain, which is thought to insert into the inner mitochondrial membrane (IMM). We found that mitochondrial swelling and depolarization was also induced by dodecyltriphenylphosphomium (DTPP), which consists of TPP and the alkyl chain, but not by TPP alone. Surprisingly, MitoQ-induced mitochondrial swelling occurred in the absence of a decrease in oxygen consumption rate. We also found that DTPP directly increased the permeability of artificial liposomes with a cardiolipin content similar to that of the IMM. In summary, MitoQ causes mitochondrial swelling and depolarization in PT cells by a mechanism unrelated to anti-oxidant activity, most likely because of increased IMM permeability due to insertion of the alkyl chain. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Increased Mitochondrial Calcium Sensitivity and Abnormal Expression of Innate Immunity Genes Precede Dopaminergic Defects in Pink1-Deficient Mice

PubMed Central

Akundi, Ravi S.; Huang, Zhenyu; Eason, Joshua; Pandya, Jignesh D.; Zhi, Lianteng; Cass, Wayne A.; Sullivan, Patrick G.; Büeler, Hansruedi

2011-01-01

Background PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca2+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1−/− mice. Methods and Findings Purified brain mitochondria of Pink1−/− mice showed impaired Ca2+ storage capacity, resulting in increased Ca2+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1−/− mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1−/− mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1−/− mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1−/− embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1−/− mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting. Conclusions Increased mitochondrial Ca2+ sensitivity and JNK activity are early defects in Pink1−/− mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1−/− mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-κB activation may predispose neurons of Pink1−/− mice to inflammation and injury-induced cell death. PMID:21249202

Altered mitochondrial function and oxidative stress in leukocytes of anorexia nervosa patients.

PubMed

Victor, Victor M; Rovira-Llopis, Susana; Saiz-Alarcon, Vanessa; Sangüesa, Maria C; Rojo-Bofill, Luis; Bañuls, Celia; Falcón, Rosa; Castelló, Raquel; Rojo, Luis; Rocha, Milagros; Hernández-Mijares, Antonio

2014-01-01

Anorexia nervosa is a common illness among adolescents and is characterised by oxidative stress. The effects of anorexia on mitochondrial function and redox state in leukocytes from anorexic subjects were evaluated. A multi-centre, cross-sectional case-control study was performed. Our study population consisted of 20 anorexic patients and 20 age-matched controls, all of which were Caucasian women. Anthropometric and metabolic parameters were evaluated in the study population. To assess whether anorexia nervosa affects mitochondrial function and redox state in leukocytes of anorexic patients, we measured mitochondrial oxygen consumption, membrane potential, reactive oxygen species production, glutathione levels, mitochondrial mass, and complex I and III activity in polymorphonuclear cells. Mitochondrial function was impaired in the leukocytes of the anorexic patients. This was evident in a decrease in mitochondrial O2 consumption (P<0.05), mitochondrial membrane potential (P<0.01) and GSH levels (P<0.05), and an increase in ROS production (P<0.05) with respect to control subjects. Furthermore, a reduction of mitochondrial mass was detected in leukocytes of the anorexic patients (P<0.05), while the activity of mitochondrial complex I (P<0.001), but not that of complex III, was found to be inhibited in the same population. Oxidative stress is produced in the leukocytes of anorexic patients and is closely related to mitochondrial dysfunction. Our results lead us to propose that the oxidative stress that occurs in anorexia takes place at mitochondrial complex I. Future research concerning mitochondrial dysfunction and oxidative stress should aim to determine the physiological mechanism involved in this effect and the physiological impact of anorexia.

Multiple pathogenic proteins implicated in neuronopathic Gaucher disease mice.

PubMed

Xu, You-hai; Xu, Kui; Sun, Ying; Liou, Benjamin; Quinn, Brian; Li, Rong-hua; Xue, Ling; Zhang, Wujuan; Setchell, Kenneth D R; Witte, David; Grabowski, Gregory A

2014-08-01

Gaucher disease, a prevalent lysosomal storage disease (LSD), is caused by insufficient activity of acid β-glucosidase (GCase) and the resultant glucosylceramide (GC)/glucosylsphingosine (GS) accumulation in visceral organs (Type 1) and the central nervous system (Types 2 and 3). Recent clinical and genetic studies implicate a pathogenic link between Gaucher and neurodegenerative diseases. The aggregation and inclusion bodies of α-synuclein with ubiquitin are present in the brains of Gaucher disease patients and mouse models. Indirect evidence of β-amyloid pathology promoting α-synuclein fibrillation supports these pathogenic proteins as a common feature in neurodegenerative diseases. Here, multiple proteins are implicated in the pathogenesis of chronic neuronopathic Gaucher disease (nGD). Immunohistochemical and biochemical analyses showed significant amounts of β-amyloid and amyloid precursor protein (APP) aggregates in the cortex, hippocampus, stratum and substantia nigra of the nGD mice. APP aggregates were in neuronal cells and colocalized with α-synuclein signals. A majority of APP co-localized with the mitochondrial markers TOM40 and Cox IV; a small portion co-localized with the autophagy proteins, P62/LC3, and the lysosomal marker, LAMP1. In cultured wild-type brain cortical neural cells, the GCase-irreversible inhibitor, conduritol B epoxide (CBE), reproduced the APP/α-synuclein aggregation and the accumulation of GC/GS. Ultrastructural studies showed numerous larger-sized and electron-dense mitochondria in nGD cerebral cortical neural cells. Significant reductions of mitochondrial adenosine triphosphate production and oxygen consumption (28-40%) were detected in nGD brains and in CBE-treated neural cells. These studies implicate defective GCase function and GC/GS accumulation as risk factors for mitochondrial dysfunction and the multi-proteinopathies (α-synuclein-, APP- and Aβ-aggregates) in nGD. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

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

2013-04-01

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

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.

Cellular and molecular perspectives in rheumatoid arthritis.

PubMed

Veale, Douglas J; Orr, Carl; Fearon, Ursula

2017-06-01

Synovial immunopathology in rheumatoid arthritis is complex involving both resident and infiltrating cells. The synovial tissue undergoes significant neovascularization, facilitating an influx of lymphocytes and monocytes that transform a typically acellular loose areolar membrane into an invasive tumour-like pannus. The microvasculature proliferates to form straight regularly-branching vessels; however, they are highly dysfunctional resulting in reduced oxygen supply and a hypoxic microenvironment. Autoantibodies such as rheumatoid factor and anti-citrullinated protein antibodies are found at an early stage, often before arthritis has developed, and they have been implicated in the pathogenesis of RA. Abnormal cellular metabolism and mitochondrial dysfunction thus ensue and, in turn, through the increased production of reactive oxygen species actively induce inflammation. Key pro-inflammatory cytokines, chemokines and growth factors and their signalling pathways, including nuclear factor κB, Janus kinase-signal transducer, are highly activated when immune cells are exposed to hypoxia in the inflamed rheumatoid joint show adaptive survival reactions by activating. This review attempts to highlight those aberrations in the innate and adaptive immune systems including the role of genetic and environmental factors, autoantibodies, cellular alterations, signalling pathways and metabolism that are implicated in the pathogenesis of RA and may therefore provide an opportunity for therapeutic intervention.

PINK1, Parkin, and Mitochondrial Quality Control: What can we Learn about Parkinson's Disease Pathobiology?

PubMed

Truban, Dominika; Hou, Xu; Caulfield, Thomas R; Fiesel, Fabienne C; Springer, Wolfdieter

2017-01-01

The first clinical description of Parkinson's disease (PD) will embrace its two century anniversary in 2017. For the past 30 years, mitochondrial dysfunction has been hypothesized to play a central role in the pathobiology of this devastating neurodegenerative disease. The identifications of mutations in genes encoding PINK1 (PTEN-induced kinase 1) and Parkin (E3 ubiquitin ligase) in familial PD and their functional association with mitochondrial quality control provided further support to this hypothesis. Recent research focused mainly on their key involvement in the clearance of damaged mitochondria, a process known as mitophagy. It has become evident that there are many other aspects of this complex regulated, multifaceted pathway that provides neuroprotection. As such, numerous additional factors that impact PINK1/Parkin have already been identified including genes involved in other forms of PD. A great pathogenic overlap amongst different forms of familial, environmental and even sporadic disease is emerging that potentially converges at the level of mitochondrial quality control. Tremendous efforts now seek to further detail the roles and exploit PINK1 and Parkin, their upstream regulators and downstream signaling pathways for future translation. This review summarizes the latest findings on PINK1/Parkin-directed mitochondrial quality control, its integration and cross-talk with other disease factors and pathways as well as the implications for idiopathic PD. In addition, we highlight novel avenues for the development of biomarkers and disease-modifying therapies that are based on a detailed understanding of the PINK1/Parkin pathway.

Metabolic profiles of exercise in patients with McArdle disease or mitochondrial myopathy

PubMed Central

Sharma, Rohit; Tadvalkar, Laura; Clish, Clary B.; Haller, Ronald G.; Mootha, Vamsi K.

2017-01-01

McArdle disease and mitochondrial myopathy impair muscle oxidative phosphorylation (OXPHOS) by distinct mechanisms: the former by restricting oxidative substrate availability caused by blocked glycogen breakdown, the latter because of intrinsic respiratory chain defects. We applied metabolic profiling to systematically interrogate these disorders at rest, when muscle symptoms are typically minimal, and with exercise, when symptoms of premature fatigue and potential muscle injury are unmasked. At rest, patients with mitochondrial disease exhibit elevated lactate and reduced uridine; in McArdle disease purine nucleotide metabolites, including xanthine, hypoxanthine, and inosine are elevated. During exercise, glycolytic intermediates, TCA cycle intermediates, and pantothenate expand dramatically in both mitochondrial disease and control subjects. In contrast, in McArdle disease, these metabolites remain unchanged from rest; but urea cycle intermediates are increased, likely attributable to increased ammonia production as a result of exaggerated purine degradation. Our results establish skeletal muscle glycogen as the source of TCA cycle expansion that normally accompanies exercise and imply that impaired TCA cycle flux is a central mechanism of restricted oxidative capacity in this disorder. Finally, we report that resting levels of long-chain triacylglycerols in mitochondrial myopathy correlate with the severity of OXPHOS dysfunction, as indicated by the level of impaired O2 extraction from arterial blood during peak exercise. Our integrated analysis of exercise and metabolism provides unique insights into the biochemical basis of these muscle oxidative defects, with potential implications for their clinical management. PMID:28716914

Ginsenoside Re protects against phencyclidine-induced behavioral changes and mitochondrial dysfunction via interactive modulation of glutathione peroxidase-1 and NADPH oxidase in the dorsolateral cortex of mice.

PubMed

Tran, The-Vinh; Shin, Eun-Joo; Dang, Duy-Khanh; Ko, Sung Kwon; Jeong, Ji Hoon; Nah, Seung-Yeol; Jang, Choon-Gon; Lee, Yu Jeung; Toriumi, Kazuya; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2017-12-01

We investigated whether ginsenoside Re (Re) modulates phencyclidine (PCP)-induced sociability deficits and recognition memory impairments to extend our recent finding. We examined the role of GPx-1 gene in the pharmacological activity of Re against mitochondrial dysfunction induced by PCP in the dorsolateral cortex of mice. Since mitochondrial oxidative stress activates NADPH oxidase (PHOX), we applied PHOX inhibitor apocynin for evaluating interactive modulation between GPx-1 and PHOX against PCP neurotoxicity. Sociability deficits and recognition memory impairments induced by PCP were more pronounced in GPx-1 knockout (KO) than in wild type (WT) mice. PCP-induced mitochondrial oxidative stress, mitochondrial dysfunction, and membrane translocation of p47phox were more evident in GPx-1 KO than in WT. Re treatment significantly attenuated PCP-induced neurotoxic changes. Re also significantly attenuated PCP-induced sociability deficits and recognition memory impairments. The attenuation by Re was comparable to that by apocynin. The attenuation was more obvious in GPx-1 KO than in WT. Importantly, apocynin did not show any additional positive effects on the neuroprotective activity of Re, indicating that PHOX is a molecular target for therapeutic activity of Re. Our results suggest that Re requires interactive modulation between GPx activity and PHOX (p47phox) to exhibit neuroprotective potentials against PCP insult. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hemin causes mitochondrial dysfunction in endothelial cells through promoting lipid peroxidation: the protective role of autophagy

PubMed Central

Higdon, Ashlee N.; Benavides, Gloria A.; Chacko, Balu K.; Ouyang, Xiaosen; Johnson, Michelle S.; Landar, Aimee; Zhang, Jianhua

2012-01-01

The hemolysis of red blood cells and muscle damage results in the release of the heme proteins myoglobin, hemoglobin, and free heme into the vasculature. The mechanisms of heme toxicity are not clear but may involve lipid peroxidation, which we hypothesized would result in mitochondrial damage in endothelial cells. To test this, we used bovine aortic endothelial cells (BAEC) in culture and exposed them to hemin. Hemin led to mitochondrial dysfunction, activation of autophagy, mitophagy, and, at high concentrations, apoptosis. To detect whether hemin induced lipid peroxidation and damaged proteins, we used derivatives of arachidonic acid tagged with biotin or Bodipy (Bt-AA, BD-AA). We found that in cells treated with hemin, Bt-AA was oxidized and formed adducts with proteins, which were inhibited by α-tocopherol. Hemin-dependent mitochondrial dysfunction was also attenuated by α-tocopherol. Protein thiol modification and carbonyl formation occurred on exposure and was not inhibited by α-tocopherol. Supporting a protective role of autophagy, the inhibitor 3-methyladenine potentiated cell death. These data demonstrate that hemin mediates cytotoxicity through a mechanism which involves protein modification by oxidized lipids and other oxidants, decreased respiratory capacity, and a protective role for the autophagic process. Attenuation of lipid peroxidation may be able to preserve mitochondrial function in the endothelium and protect cells from heme-dependent toxicity. PMID:22245770

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.

Coenzyme Q10 Prevents Mitochondrial Dysfunction and Facilitates Pharmacological Activity of Atorvastatin in 6-OHDA Induced Dopaminergic Toxicity in Rats.

PubMed

Prajapati, Santosh Kumar; Garabadu, Debapriya; Krishnamurthy, Sairam

2017-05-01

Atorvastatin (ATV) generally used to treat dyslipidemia is also reported to have effect against 6-hydroxydopamine (6-OHDA) induced neurotoxicity. Additionally, atorvastatin can interfere with mitochondrial function by reducing the level of Q10. Therefore, the therapeutic effect of atorvastatin (20 mg/kg) could be compromised. In this context, the present study evaluated the effect of ATV supplemented with Q10. 6-OHDA was unilaterally injected into the right striatum of male rats. On day 8 of 6-OHDA infusion, ATV (20 mg/kg), Q10 (200 mg/kg), and their combination were administered per oral for 14 days. On day 21, there was significant loss of striatal dopamine indicating neurotoxicity. The combination of ATV+Q10 showed significant amelioration of dopamine (DA) toxicity compared to individual treatments. Similarly, ATV+Q10 compared to individual treatment significantly decreased the motor deficits induced by 6-OHDA. Further, 6-OHDA induced mitochondrial dysfunction in the substantia nigra pars compacta (SNpc). There was significant decrease in mitochondrial complex enzyme activities and mitochondrial membrane potential (MMP). Treatment with ATV and ATV+Q10 ameliorated mitochondrial dysfunction by increasing complex enzyme activities; however, only ATV+Q10 were able to stabilize MMP and maintained mitochondrial integrity. Moreover, there was significant induction of oxidative stress as observed from increase in lipid peroxidases (LPO) and nitrite (NO), and decrease in super oxide dismutase (SOD). Treatment with ATV+Q10 significantly altered the above effects indicating antioxidant activity. Furthermore, only combination of ATV and Q10 decreased the 6-OHDA induced expression of cytochrome-C, caspase-9 and caspase-3. Therefore, current results provide evidence that supplementation of Q10 with ATV shows synergistic effect in reducing dopamine toxicity.

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

PubMed

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

2012-08-01

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

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

PubMed Central

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

2014-01-01

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

Mitochondria, Estrogen and Female Brain Aging

PubMed Central

Lejri, Imane; Grimm, Amandine; Eckert, Anne

2018-01-01

Mitochondria play an essential role in the generation of steroid hormones including the female sex hormones. These hormones are, in turn, able to modulate mitochondrial activities. Mitochondria possess crucial roles in cell maintenance, survival and well-being, because they are the main source of energy as well as of reactive oxygen species (ROS) within the cell. The impairment of these important organelles is one of the central features of aging. In women’s health, estrogen plays an important role during adulthood not only in the estrous cycle, but also in the brain via neuroprotective, neurotrophic and antioxidant modes of action. The hypestrogenic state in the peri- as well as in the prolonged postmenopause might increase the vulnerability of elderly women to brain degeneration and age-related pathologies. However, the underlying mechanisms that affect these processes are not well elucidated. Understanding the relationship between estrogen and mitochondria might therefore provide better insights into the female aging process. Thus, in this review, we first describe mitochondrial dysfunction in the aging brain. Second, we discuss the estrogen-dependent actions on the mitochondrial activity, including recent evidence of the estrogen—brain-derived neurotrophic factor and estrogen—sirtuin 3 (SIRT3) pathways, as well as their potential implications during female aging. PMID:29755342

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

Xie, Yuchao; McGill, Mitchell R.; Du, Kuo

3′-Hydroxyacetanilide or N-acetyl-meta-aminophenol (AMAP) is generally regarded as a non-hepatotoxic analog of acetaminophen (APAP). Previous studies demonstrated the absence of toxicity after AMAP in mice, hamsters, primary mouse hepatocytes and several cell lines. In contrast, experiments with liver slices suggested that it may be toxic to human hepatocytes; however, the mechanism of toxicity is unclear. To explore this, we treated primary human hepatocytes (PHH) with AMAP or APAP for up to 48 h and measured several parameters to assess metabolism and injury. Although less toxic than APAP, AMAP dose-dependently triggered cell death in PHH as indicated by alanine aminotransferase (ALT)more » release and propidium iodide (PI) staining. Similar to APAP, AMAP also significantly depleted glutathione (GSH) in PHH and caused mitochondrial damage as indicated by glutamate dehydrogenase (GDH) release and the JC-1 assay. However, unlike APAP, AMAP treatment did not cause relevant c-jun-N-terminal kinase (JNK) activation in the cytosol or phospho-JNK translocation to mitochondria. To compare, AMAP toxicity was assessed in primary mouse hepatocytes (PMH). No cytotoxicity was observed as indicated by the lack of lactate dehydrogenase release and no PI staining. Furthermore, there was no GSH depletion or mitochondrial dysfunction after AMAP treatment in PMH. Immunoblotting for arylated proteins suggested that AMAP treatment caused extensive mitochondrial protein adduct formation in PHH but not in PMH. In conclusion, AMAP is hepatotoxic in PHH and the mechanism involves the formation of mitochondrial protein adducts and mitochondrial dysfunction. - Highlights: • AMAP induces cell death in primary human hepatocytes (PHH). • AMAP does not cause cell death in primary mouse hepatocytes (PMH). • AMAP leads to mitochondria dysfunction in PHH but not PMH. • Protein adduct formation and dysfunction in mitochondria correlate with toxicity.« less

CR108, a novel vitamin K3 derivative induces apoptosis and breast tumor inhibition by reactive oxygen species and mitochondrial dysfunction.

PubMed

Yang, Chun-Ru; Liao, Wei-Siang; Wu, Ya-Hui; Murugan, Kaliyappan; Chen, Chinpiao; Chao, Jui-I

2013-12-15

Vitamin K3 derivatives have been shown to exert anticancer activities. Here we show a novel vitamin K3 derivative (S)-2-(2-hydroxy-3-methylbutylthio)naphthalene-1,4-dione, which is named as CR108 that induces apoptosis and tumor inhibition through reactive oxygen species (ROS) and mitochondrial dysfunction in human breast cancer. CR108 is more effective on the breast cancer cell death than other vitamin K3 derivatives. Moreover, CR108 induced apoptosis in both the non-HER-2-overexpressed MCF-7 and HER-2-overexpressed BT-474 breast cancer cells. CR108 caused the loss of mitochondrial membrane potential, cytochrome c released from mitochondria to cytosol, and cleaved PARP proteins for apoptosis induction. CR108 markedly increased ROS levels in breast cancer cells. N-acetylcysteine (NAC), a general ROS scavenger, completely blocked the CR108-induced ROS levels, mitochondrial dysfunction and apoptosis. Interestingly, CR108 increased the phosphorylation of p38 MAP kinase but conversely inhibited the survivin protein expression. NAC treatment prevented the activation of p38 MAP kinase and rescued the survivin protein levels. SB202190, a specific p38 MAP kinase inhibitor, recovered the survivin protein levels and attenuated the cytotoxicity of CR108-treated cells. Furthermore, CR108 inhibited the xenografted human breast tumor growth in nude mice. Together, we demonstrate that CR108 is a novel vitamin K3 derivative that induces apoptosis and tumor inhibition by ROS production and mitochondrial dysfunction and associates with the phosphorylation of p38 MAP kinase and the inhibition of survivin in the human breast cancer. © 2013.

Albumin Overload and PINK1/Parkin Signaling-Related Mitophagy in Renal Tubular Epithelial Cells.

PubMed

Tan, Jin; Xie, Qi; Song, Shuling; Miao, Yuyang; Zhang, Qiang

2018-03-01

BACKGROUND Albumin, as a major urinary protein component, is a risk factor for chronic kidney disease progression. Mitochondrial dysfunction is one of the main causes of albumin-induced proximal tubule cells injury. Mitophagy is considered as a pivotal protective mechanism for the elimination of dysfunctional mitochondria. The objective of this research was to determine whether albumin overload-induced mitochondrial dysfunction can activate PINK1/Parkin-mediated mitophagy in renal tubular epithelial cells (TECs). MATERIAL AND METHODS Immunofluorescence assay and Western blot assay were used to detect the effects of albumin overload on autophagy marker protein LC3. Transmission electron microscopy and Western blot assay were used to investigate the role of albumin in mitochondrial injury. Western blot assay and co-localization of acidic lysosomes and mitochondria assay were employed to detect the activation of mitophagy induced by albumin. Finally, we explored the role of PINK1/Parkin signaling in albumin-induced mitophagy by inhibiting mitophagy by knockdown of PARK2 (Parkin) level. RESULTS Immunofluorescence and Western blot results showed that the expression level of LC3-II increased, and the maximum increase point was observed after 8 h of albumin treatment. Transmission electron microscopy results demonstrated that albumin overload-induced mitochondrial injury and quantity of autophagosomes increased. Additionally, expression of PINK1 and cytosolic cytochrome C increased and mitochondria cytochrome C decreased in the albumin group. The co-localization of acidic lysosomes and mitochondria demonstrated that the number of albumin overload-induced mitophagy-positive dots increased. The transient transfection of PARK2 siRNA result showed knockdown of the expression level of PARK2 can inhibit mitophagy induced by albumin. CONCLUSIONS In conclusion, our study suggests that mitochondrial dysfunction activates the PINK1/Parkin signaling and mitophagy in renal tubular epithelial cells under albumin overload condition.

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

PubMed Central

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

2017-01-01

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

Mitochondria and Cardiovascular Aging

PubMed Central

Dai, Dao-Fu; Ungvari, Zoltan

2013-01-01

Old age is a major risk factor for cardiovascular diseases. Several lines of evidence in experimental animal models have indicated the central role of mitochondria both in lifespan determination and cardiovascular aging. In this article we review the evidence supporting the role of mitochondrial oxidative stress, mitochondrial damage and biogenesis as well as the crosstalk between mitochondria and cellular signaling in cardiac and vascular aging. Intrinsic cardiac aging in the murine model closely recapitulates age-related cardiac changes in humans (left ventricular hypertrophy, fibrosis and diastolic dysfunction), while the phenotype of vascular aging include endothelial dysfunction, reduced vascular elasticity and chronic vascular inflammation. Both cardiac and vascular aging involve neurohormonal signaling (e.g. renin-angiotensin, adrenergic, insulin-IGF1 signaling) and cell-autonomous mechanisms. The potential therapeutic strategies to improve mitochondrial function in aging and cardiovascular diseases are also discussed, with a focus on mitochondrial-targeted antioxidants, calorie restriction, calorie restriction mimetics and exercise training. PMID:22499901

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

PubMed

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

2016-09-01

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

The potential of vitamin K3 as an anticancer agent against breast cancer that acts via the mitochondria-related apoptotic pathway.

PubMed

Akiyoshi, Takeshi; Matzno, Sumio; Sakai, Mika; Okamura, Noboru; Matsuyama, Kenji

2009-12-01

We tried to clarify the cytotoxic mechanism of VK(3) using the breast cancer cell line MCF-7. Cytotoxicity was measured via intracellular esterase activity. DNA fragmentation was assessed by agarose gel electrophoresis. JC-1 staining was applied to measure mitochondrial dysfunction. Caspase activation and reactive oxidative species (ROS) generation were also measured. VK(3) exhibited cytotoxicity that caused DNA fragmentation in MCF-7 cells with an IC(50) of 14.2 microM. JC-1 staining revealed that VK(3) caused mitochondrial dysfunction including a disappearance of mitochondrial membrane potential. Additional investigation showed that the mitochondrial damage was induced by the generation of ROS and the subsequent activation of caspase-7 and -9. Our findings demonstrate that VK(3)-induced apoptosis is selectively initiated by the mitochondria-related pathway and might be useful in breast cancer chemotherapy.

Mitochondrial Dysfunction in Parkinson's Disease: Pathogenesis and Neuroprotection

PubMed Central

Mounsey, Ross B.; Teismann, Peter

2011-01-01

Mitochondria are vitally important organelles involved in an array of functions. The most notable is their prominent role in energy metabolism, where they generate over 90% of our cellular energy in the form of ATP through oxidative phosphorylation. Mitochondria are involved in various other processes including the regulation of calcium homeostasis and stress response. Mitochondrial complex I impairment and subsequent oxidative stress have been identified as modulators of cell death in experimental models of Parkinson's disease (PD). Identification of specific genes which are involved in the rare familial forms of PD has further augmented the understanding and elevated the role mitochondrial dysfunction is thought to have in disease pathogenesis. This paper provides a review of the role mitochondria may play in idiopathic PD through the study of experimental models and how genetic mutations influence mitochondrial activity. Recent attempts at providing neuroprotection by targeting mitochondria are described and their progress assessed. PMID:21234411

Understanding the origin of non-immune cell-mediated weakness in the idiopathic inflammatory myopathies - potential role of ER stress pathways.

PubMed

Lightfoot, Adam P; Nagaraju, Kanneboyina; McArdle, Anne; Cooper, Robert G

2015-11-01

Discussion of endoplasmic reticulum (ER) stress pathway activation in idiopathic inflammatory myopathies (IIM), and downstream mechanisms causative of muscle weakness. In IIM, ER stress is an important pathogenic process, but how it causes muscle dysfunction is unknown. We discuss relevant pathways modified in response to ER stress in IIM: reactive oxygen species (ROS) generation and mitochondrial dysfunction, and muscle cytokine (myokine) generation. First, ER stress pathway activation can induce changes in mitochondrial bioenergetics and ROS production. ROS can oxidize cellular components, causing muscle contractile dysfunction and energy deficits. Novel compounds targeting ROS generation and/or mitochondrial dysfunction can improve muscle function in several myopathologies. Second, recent research has demonstrated that skeletal muscle produces multiple myokines. It is suggested that these play a role in causing muscle weakness. Myokines are capable of immune cell recruitment, thus contributing to perturbed muscle function. A characterization of myokines in IIM would clarify their pathogenic role, and so identify new therapeutic targets. ER stress pathway activation is clearly of etiological relevance in IIM. Research to better understand mechanisms of weakness downstream of ER stress is now required, and which may discover new therapeutic targets for nonimmune cell-mediated weakness.

Regulation of mitochondrial biogenesis and its intersection with inflammatory responses.

PubMed

Cherry, Anne D; Piantadosi, Claude A

2015-04-20

Mitochondria play a vital role in cellular homeostasis and are susceptible to damage from inflammatory mediators released by the host defense. Cellular recovery depends, in part, on mitochondrial quality control programs, including mitochondrial biogenesis. Early-phase inflammatory mediator proteins interact with PRRs to activate NF-κB-, MAPK-, and PKB/Akt-dependent pathways, resulting in increased expression or activity of coactivators and transcription factors (e.g., PGC-1α, NRF-1, NRF-2, and Nfe2l2) that regulate mitochondrial biogenesis. Inflammatory upregulation of NOS2-induced NO causes mitochondrial dysfunction, but NO is also a signaling molecule upregulating mitochondrial biogenesis via PGC-1α, participating in Nfe2l2-mediated antioxidant gene expression and modulating inflammation. NO and reactive oxygen species generated by the host inflammatory response induce the redox-sensitive HO-1/CO system, causing simultaneous induction of mitochondrial biogenesis and antioxidant gene expression. Recent evidence suggests that mitochondrial biogenesis and mitophagy are coupled through redox pathways; for instance, parkin, which regulates mitophagy in chronic inflammation, may also modulate mitochondrial biogenesis and is upregulated through NF-κB. Further research on parkin in acute inflammation is ongoing. This highlights certain common features of the host response to acute and chronic inflammation, but caution is warranted in extrapolating findings across inflammatory conditions. Inflammatory mitochondrial dysfunction and oxidative stress initiate further inflammatory responses through DAMP/PRR interactions and by inflammasome activation, stimulating mitophagy. A deeper understanding of mitochondrial quality control programs' impact on intracellular inflammatory signaling will improve our approach to the restoration of mitochondrial homeostasis in the resolution of acute inflammation.

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.

Autism in the Son of a Woman with Mitochondrial Myopathy and Dysautonomia: A Case Report.

PubMed

Brown, Bradley D; Rais, Theodore

2015-01-01

The relationship between autism spectrum disorders and mitochondrial dysfunction, including mitochondrial myopathies and other mitochondrial diseases, is an area of ongoing research. All autism spectrum disorders are known to be heritable, via genetic and/or epigenetic mechanisms, but specific modes of inheritance are not well characterized. Nevertheless, autism spectrum disorders have been linked to many specific genes associated with mitochondrial function, especially to genes involved in mitochondrial tRNA and the electron transport chain, both particularly vulnerable to point mutations, and clinical research also supports a relationship between the two pathologies. Although only a small minority of patients with autism have a mitochondrial disease, many patients with mitochondrial myopathies have autism spectrum disorder symptoms, and these symptoms may be the presenting symptoms, which presents a diagnostic challenge for clinicians. The authors report the case of a 15-year-old boy with a history of autism spectrum disorder and neurocardiogenic syncope, admitted to the inpatient unit for self-injury, whose young mother, age 35, was discovered to suffer from mitochondrial myopathy, dysautonomia, neurocardiogenic syncope, Ehler-Danlos syndrome, and other uncommon multisystem pathologies likely related to mitochondrial dysfunction. This case illustrates the need for a high index of suspicion for mitochondrial disease in patients with autism, as they have two orders of magnitude greater risk for such diseases than the general population. The literature shows that mitochondrial disease is underdiagnosed in autism spectrum disorder patients and should not be viewed as a "zebra" (i.e., an obscure diagnosis that is made when a more common explanation is more likely).