cytochrome-c-t and Mitochondrial-Myopathies

It is still unclear why anthracycline treatment results in a cardiac-specific myopathy. We investigated whether selective doxorubicin (DOX) cardiotoxicity involving mitochondrial degeneration is explained by different respiratory complexes reserves between tissues by comparing and contrasting treatment effects in heart vs liver and kidney. Alternatively, we have also explored if the degeneration is due to alterations of mitochondrial thresholds to incompatible states.. Heart, liver and kidney mitochondria were isolated from male Wistar rats weekly injected with DOX during 7weeks. Global flux and isolated step curves were obtained for Complex I, III, IV, as well as for the adenine nucleotide translocator. We show treatment-related alterations in global flux curve for Complex III in all analyzed tissues and in Complex IV activity curve solely in heart. However, all mitochondrial threshold curves remained unchanged after treatment in the analyzed tissues. No treatment-related differences were detected on transcript or protein analysis of selected respiratory complexes subunits. However, a specific loss of cytochrome c and cardiolipin was measured in heart, but not in other organs, mitochondria from DOX-treated animals.. Contrary to our hypothesis, impaired mitochondrial respiration could not be explained by intrinsic differences in respiratory complexes reserves among tissues or, by alterations in mitochondrial thresholds after treatment. Instead, we propose that loss of cytochrome c and cardiolipin are responsible for the depressed mitochondrial respiration observed after chronic DOX treatment. Moreover, cardiac cytochrome c and cardiolipin depletion decreases metabolic network buffering, hindering cardiac ability to respond to increased workload, accelerating cardiac aging.

Topics: Animals; Antibiotics, Antineoplastic; Cardiolipins; Cytochromes c; Doxorubicin; Kidney; Liver; Male; Mitochondria; Mitochondrial Myopathies; Myocardium; Rats, Wistar

Long-chain 3-hydroxylated fatty acids (LCHFA) accumulate in long-chain 3-hydroxy-acyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (MTP) deficiencies. Affected patients usually present severe neonatal symptoms involving cardiac and hepatic functions, although long-term neurological abnormalities are also commonly observed. Since the underlying mechanisms of brain damage are practically unknown and have not been properly investigated, we studied the effects of LCHFA on important parameters of mitochondrial homeostasis in isolated mitochondria from cerebral cortex of developing rats. 3-Hydroxytetradecanoic acid (3 HTA) reduced mitochondrial membrane potential, NAD(P)H levels, Ca(2+) retention capacity and ATP content, besides inducing swelling, cytochrome c release and H2O2 production in Ca(2+)-loaded mitochondrial preparations. We also found that cyclosporine A plus ADP, as well as ruthenium red, a Ca(2+) uptake blocker, prevented these effects, suggesting the involvement of the mitochondrial permeability transition pore (mPTP) and an important role for Ca(2+), respectively. 3-Hydroxydodecanoic and 3-hydroxypalmitic acids, that also accumulate in LCHAD and MTP deficiencies, similarly induced mitochondrial swelling and decreased ATP content, but to a variable degree pending on the size of their carbon chain. It is proposed that mPTP opening induced by LCHFA disrupts brain bioenergetics and may contribute at least partly to explain the neurologic dysfunction observed in patients affected by LCHAD and MTP deficiencies.

Topics: 3-Hydroxyacyl CoA Dehydrogenases; Acyl-CoA Dehydrogenase, Long-Chain; Adenosine Triphosphate; Animals; Calcium; Cardiomyopathies; Cerebral Cortex; Cytochromes c; Energy Metabolism; Homeostasis; Hydrogen Peroxide; Lauric Acids; Lipid Metabolism, Inborn Errors; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Myopathies; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Mitochondrial Trifunctional Protein; Myristic Acids; NADP; Nervous System Diseases; Oxidants; Palmitic Acids; Rats; Rats, Wistar; Rhabdomyolysis

The importance of mitochondrial biogenesis in the pathogenesis of mitochondrial diseases has been widely recognised but little is known about it with regard to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) syndrome. Since such knowledge would contribute to the understanding of the pathogenesis of this disease, we designed a study to provide comprehensive overview of mitochondrial biogenesis in cybrid cells harboring NARP mutation (8993T>G). We also used Rho0 cells with the same nuclear background to show that distinct mtDNA defects lead to distinct cellular responses irrespective of nuclear genome. Mitochondrial biogenesis is regulated by mitochondria-to-nucleus (retrograde) communication which depends on intracellular signaling pathways sensitive to ROS. Since we previously found that selenite lowered ROS in NARP cybrids, we hypothesised that selenite could also modulate mitochondrial biogenesis in these cells. Although the mitochondrial mass was not changed in NARP cybrids, we showed the compensatory upregulation of respiratory chain subunits which prompted us to investigate the transcription factors that regulate their expression such as PGC-1α, NRFs, and TFAM. Selenite supplementation increased the level of NRF1 and nuclear accumulation of NRF2, but we did not detect any major changes in the levels of investigated respiratory chain proteins. These subtle changes in mitochondrial biogenesis in response to selenite treatment support the hypothesis that selenite could be considered as a potential therapeutic agent of NARP syndrome due to its antioxidant properties. Moreover, it could also be tested with regard to other mitochondrial disorders associated with ROS overproduction.

Topics: Cell Line, Tumor; Cells, Cultured; Cytochromes c; Dietary Supplements; DNA-Binding Proteins; DNA, Mitochondrial; Fibroblasts; Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Humans; Immunohistochemistry; Ion Channels; Mitochondria; Mitochondrial Myopathies; Mitochondrial Proteins; Mutation; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Phosphorylation; Retinitis Pigmentosa; Sodium Selenite; Transcription Factors; Uncoupling Protein 3