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Biochimica Et Biophysica Acta.... Feb 2018Frataxin-deficient neonatal rat cardiomyocytes and dorsal root ganglia neurons have been used as cell models of Friedreich ataxia. In previous work we show that frataxin...
Frataxin-deficient neonatal rat cardiomyocytes and dorsal root ganglia neurons have been used as cell models of Friedreich ataxia. In previous work we show that frataxin depletion resulted in mitochondrial swelling and lipid droplet accumulation in cardiomyocytes, and compromised DRG neurons survival. Now, we show that these cells display reduced levels of the mitochondrial calcium transporter NCLX that can be restored by calcium-chelating agents and by external addition of frataxin fused to TAT peptide. Also, the transcription factor NFAT3, involved in cardiac hypertrophy and apoptosis, becomes activated by dephosphorylation in both cardiomyocytes and DRG neurons. In cardiomyocytes, frataxin depletion also results in mitochondrial permeability transition pore opening. Since the pore opening can be inhibited by cyclosporin A, we show that this treatment reduces lipid droplets and mitochondrial swelling in cardiomyocytes, restores DRG neuron survival and inhibits NFAT dephosphorylation. These results highlight the importance of calcium homeostasis and that targeting mitochondrial pore by repurposing cyclosporin A, could be envisaged as a new strategy to treat the disease.
Topics: Animals; Animals, Newborn; Apoptosis; Calcineurin; Calcium; Cell Survival; Cyclosporine; Disease Models, Animal; Friedreich Ataxia; Ganglia, Spinal; Iron-Binding Proteins; Lipids; Lymphocytes; Membrane Potential, Mitochondrial; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Myocytes, Cardiac; NFATC Transcription Factors; Neurons; Permeability; Phosphorylation; Rats; Rats, Sprague-Dawley; Sodium-Calcium Exchanger; Frataxin
PubMed: 29223733
DOI: 10.1016/j.bbadis.2017.12.005 -
British Journal of Pharmacology Feb 20051. Herein we study the effects of the mitochondrial complex II inhibitor malonate on its primary target, the mitochondrion. 2. Malonate induces mitochondrial potential...
1. Herein we study the effects of the mitochondrial complex II inhibitor malonate on its primary target, the mitochondrion. 2. Malonate induces mitochondrial potential collapse, mitochondrial swelling, cytochrome c (Cyt c) release and depletes glutathione (GSH) and nicotinamide adenine dinucleotide coenzyme (NAD(P)H) stores in brain-isolated mitochondria. 3. Although, mitochondrial potential collapse was almost immediate after malonate addition, mitochondrial swelling was not evident before 15 min of drug presence. This latter effect was blocked by cyclosporin A (CSA), Ruthenium Red (RR), magnesium, catalase, GSH and vitamin E. 4. Malonate added to SH-SY5Y cell cultures produced a marked loss of cell viability together with the release of Cyt c and depletion of GSH and NAD(P)H concentrations. All these effects were not apparent in SH-SY5Y cells overexpressing Bcl-xL. 5. When GSH concentrations were lowered with buthionine sulphoximine, cytoprotection afforded by Bcl-xL overexpression was not evident anymore. 6. Taken together, all these data suggest that malonate causes a rapid mitochondrial potential collapse and reactive oxygen species production that overwhelms mitochondrial antioxidant capacity and leads to mitochondrial swelling. Further permeability transition pore opening and the subsequent release of proapoptotic factors such as Cyt c could therefore be, at least in part, responsible for malonate-induced toxicity.
Topics: Animals; Cell Death; Cell Line; Cell Survival; Cytochromes c; DNA Fragmentation; Glutathione; Ion Channels; Malonates; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; NADP; Oxidation-Reduction; Prosencephalon; Proto-Oncogene Proteins c-bcl-2; Rats; Reactive Oxygen Species; bcl-X Protein
PubMed: 15655518
DOI: 10.1038/sj.bjp.0706069 -
Mitochondrial function and actin regulate dynamin-related protein 1-dependent mitochondrial fission.Current Biology : CB Apr 2005Mitochondria display a variety of shapes, ranging from small and spherical or the classical tubular shape to extended networks. Shape transitions occur frequently and... (Comparative Study)
Comparative Study
Mitochondria display a variety of shapes, ranging from small and spherical or the classical tubular shape to extended networks. Shape transitions occur frequently and include fusion, fission, and branching. It was reported that some mitochondrial shape transitions are developmentally regulated, whereas others were linked to disease or apoptosis. However, if and how mitochondrial function controls mitochondrial shape through regulation of mitochondrial fission and fusion is unclear. Here, we show that inhibitors of electron transport, ATP synthase, or the permeability transition pore (mtPTP) induced reversible mitochondrial fission. Mitochondrial fission depended on dynamin-related protein 1 (DRP1) and F-actin: Disruption of F-actin attenuated fission and recruitment of DRP1 to mitochondria. In contrast, uncoupling of electron transport and oxidative phosphorylation caused mitochondria to adopt a distinct disk shape. This shape change was independent of the cytoskeleton and DRP1 and was most likely caused by swelling. Thus, disruption of mitochondrial function rapidly and reversibly altered mitochondrial shape either by activation of DRP1-dependent fission or by swelling, indicating a close relationship between mitochondrial fission, shape, and function. Furthermore, our results suggest that the actin cytoskeleton is involved in mitochondrial fission by facilitating mitochondrial recruitment of DRP1.
Topics: Actins; Animals; Blotting, Western; Cells, Cultured; Chlorocebus aethiops; Dynamins; Fluorescent Antibody Technique; Luminescent Proteins; Mice; Microscopy, Electron, Transmission; Microtubule-Associated Proteins; Mitochondria; Mitochondrial Swelling; Red Fluorescent Protein
PubMed: 15823542
DOI: 10.1016/j.cub.2005.02.064 -
European Journal of Biochemistry May 1991The effects of mitochondrial swelling and calcium have been used to study the possible function of the glutamine transporter in regulating glutamine hydrolysis....
The effects of mitochondrial swelling and calcium have been used to study the possible function of the glutamine transporter in regulating glutamine hydrolysis. Salt-induced swelling of pig renal mitochondria and an iso-osmotic mixed salt solution and swelling caused by reducing the osmolarity of the incubation medium, are accompanied by activation of glutamine hydrolysis. Regulation of the glutaminase activity by salt-induced mitochondrial swelling is likely to have physiological importance, similar to the regulation of hepatic glutaminase by changing the matrix volume, that has been described by others. 0.1-1.0 mM calcium stimulates glutamine hydrolysis and the calcium activation curve follows Michaelis-Menten kinetics. The calcium activation is reversible, it is unaffected by phosphate, high glutamine and mitochondrial calcium uptake, as well as by sonication and the activation is calmodulin independent. The calcium activation is additive to that of swelling. Similar to calcium, hypo-osmotic swelling mainly increases the apparent Vmax for glutamine, whereas the apparent Km is little changed, indicating that the effects are primarily on the phosphate-activated glutaminase itself rather than on the glutamine transporter. Furthermore, calcium which activates glutamine hydrolysis, inhibits glutamine uptake into the mitochondria and so does alanine having no effect on glutamine hydrolysis. Therefore, it is indicative that glutamine transport is not rate limiting for glutamine hydrolysis.
Topics: Animals; Biological Transport; Calcium; Glutaminase; Glutamine; Hydrolysis; In Vitro Techniques; Kidney; Mitochondria; Mitochondrial Swelling; Osmotic Pressure; Phosphates; Rats; Swine
PubMed: 2029898
DOI: 10.1111/j.1432-1033.1991.tb15958.x -
The Journal of Biophysical and... Jan 1959Reduced glutathione, in concentrations approximating those occurring in intact rat liver, causes swelling of rat liver mitochondria in vitro which is different in...
Reduced glutathione, in concentrations approximating those occurring in intact rat liver, causes swelling of rat liver mitochondria in vitro which is different in kinetics and extent from that yielded by L-thyroxine. The effect is also given by cysteine, which is more active, and reduced coenzyme A, but not by L-ascorbate, cystine, or oxidized glutathione. The optimum pH is 6.5, whereas thyroxine-induced swelling is optimal at pH 7.5. The GSH-induced swelling is not inhibited by DNP or dicumarol, nor by high concentrations of sucrose, serum albumin, or polyvinylpyrrolidone, in contrast to thyroxine-induced swelling. ATP inhibits the GSH swelling, but ADP and AMP are ineffective. Mn(-+) is a very potent inhibitor, but Mg(++) is ineffective. Ethylenediaminetetraacetate is also an effective inhibitor of GSH-induced swelling. The respiratory inhibitors amytal and antimycin A do not inhibit the swelling action of GSH, but cyanide does; these findings are consistent with the view that the oxidation-reduction state of the respiratory chain between cytochrome c and oxygen is a determinant of GSH-induced swelling. Reversal of GSH-induced swelling by osmotic means or by ATP in KCl media could not be observed. Large losses of nucleotides and protein occur during the swelling by GSH, suggesting that the action is irreversible. The characteristically drastic swelling action of GSH could be prevented if L-thyroxine was also present in the medium.
Topics: Animals; Ascorbic Acid; Cysteine; Cytochromes c; Electron Transport; Glutathione; Glutathione Disulfide; Liver; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Oxidation-Reduction; Rats; Thyroxine
PubMed: 13630941
DOI: 10.1083/jcb.5.1.109 -
Neurochemistry International Jun 2007Mitochondria, being the principal source of cellular energy, are vital for cell life. Yet, ironically, they are also major mediators of cell death, either by necrosis or... (Review)
Review
Mitochondria, being the principal source of cellular energy, are vital for cell life. Yet, ironically, they are also major mediators of cell death, either by necrosis or apoptosis. One means by which these adverse effects occur is through the mitochondrial permeability transition (mPT) whereby the inner mitochondrial membrane suddenly becomes excessively permeable to ions and other solutes, resulting in a collapse of the inner membrane potential, ultimately leading to energy failure and cell necrosis. The mPT may also bring about the release of various factors known to cause apoptotic cell death. The principal factors leading to the mPT are elevated levels of intracellular Ca2+ and oxidative stress. Characteristically, the mPT is inhibited by cyclosporin A. This article will briefly discuss the concept of the mPT, its molecular composition, its inducers and regulators, agents that influence its activity and describe the consequences of its induction. Lastly, we will review its potential contribution to acute neurological disorders, including ischemia, trauma, and toxic-metabolic conditions, as well as its role in chronic neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis.
Topics: Alzheimer Disease; Calcium; Energy Metabolism; Humans; Huntington Disease; Hyperglycemia; Manganese; Mitochondrial Membranes; Mitochondrial Swelling; Motor Neuron Disease; Nervous System Diseases; Neurodegenerative Diseases; Neurotoxins; Parkinsonian Disorders; Permeability
PubMed: 17397969
DOI: 10.1016/j.neuint.2007.02.008 -
Circulation Sep 2013Cardiac myocytes demonstrate significant swelling and associated reduced contractility in response to stress that is prevented by the ATP-sensitive potassium channel...
BACKGROUND
Cardiac myocytes demonstrate significant swelling and associated reduced contractility in response to stress that is prevented by the ATP-sensitive potassium channel opener, diazoxide (DZX) via an unknown mechanism. One proposed mechanism of cardioprotection is mitochondrial matrix swelling. To establish the relationship between mitochondrial and cellular volume during stress, this study examined the effect of DZX on mitochondrial volume.
METHODS AND RESULTS
Isolated mouse mitochondria were exposed to the following solutions: Tyrode, isolation buffer, cardioplegia (CPG)±DZX±ATP-sensitive potassium channel inhibitor, 5-hydroxydecanoate, and metabolic inhibition (MI) ± DZX ± 5-hydroxydecanoate. Mitochondrial volume was measured. DZX resulted in significant mitochondrial swelling (P<0.0001 versus Tyrode). MI and CPG resulted in significant mitochondrial swelling compared with baseline volume. The addition of DZX did not alter the response of mitochondrial volume to CPG (P=0.912) but increased swelling in response to MI (P=0.036). The addition of 5-hydroxydecanoate to MI + DZX or CPG+DZX significantly reduced mitochondrial swelling (P<0.003 MI+DZX versus MI + DZX + 5HD; P<0.001 CPG+DZX versus CPG + DZX + 5HD).
CONCLUSIONS
Both cellular and mitochondrial volume increased during exposure to MI and CPG. DZX did not alter mitochondrial volume during CPG; however, it was associated with an increase in mitochondrial volume during MI. 5-Hydroxydecanoate reduced mitochondrial volume during exposure to both stresses with DZX, supporting a role for a mitochondrial ATP-sensitive potassium channel in the mechanism of cardioprotection by DZX.
Topics: Animals; Cell Size; Diazoxide; Female; KATP Channels; Male; Mice; Mice, Inbred C57BL; Mitochondria, Heart; Mitochondrial Size; Mitochondrial Swelling; Oxidative Stress
PubMed: 24030396
DOI: 10.1161/CIRCULATIONAHA.112.000128 -
The Biochemical Journal Aug 1970Mitochondrial swelling induced by valinomycin, calcium chloride and P(i) was studied after potassium permanganate fixation in suspension. Valinomycin induces a rapid...
Mitochondrial swelling induced by valinomycin, calcium chloride and P(i) was studied after potassium permanganate fixation in suspension. Valinomycin induces a rapid K(+) influx, increase of the matrix space and out-folding of the cristae, with good preservation of the matrix material. This swelling is reversible but the cristae do not completely re-form and have a blebbed appearance. On repeated swelling and contraction cycles there is a gradual loss of matrix material. Calcium chloride and P(i) produce a slow swelling of the matrix space. Shrinkage induced by ATP was partial and not associated with return to the original structure.
Topics: Adenosine Triphosphate; Animals; Anti-Bacterial Agents; Calcium Chloride; In Vitro Techniques; Microscopy, Electron; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Phosphorus; Potassium; Rats
PubMed: 5476731
DOI: 10.1042/bj1180883 -
The Journal of Cell Biology Jul 1964Streptolysins S and O from hemolytic streptococci were found to induce mitochondrial swelling and the release of malic dehydrogenase from mitochondria; no other...
Streptolysins S and O from hemolytic streptococci were found to induce mitochondrial swelling and the release of malic dehydrogenase from mitochondria; no other streptococcal products were as active. Mg(++), cyanide, dinitrophenol, bovine serum albumin, and antimycin all inhibited streptolysin-induced mitochondrial swelling; only the latter two agents prevented release of malic dehydrogenase from the particles. The streptolysins also solubilized beta-glucuronidase from the less numerous lysosomes of mitochondrial fractions. Vitamin A induced swelling of mitochondria with release of malic dehydrogenase and, at higher concentrations, release of beta-glucuronidase. In these effects, streptolysin S and vitamin A resembled cysteine and ascorbate, which induced swelling and lysis of mitochondria together with solubilization of enzymes. In contrast, mitochondrial swelling induced by such agents as phosphate, thyroxine, or substrates was not accompanied by release of enzymes. The release of enzymes from particles is suggested as a criterion for distinguishing "lytic" agents from those which induce mitochondrial swelling dependent upon electron transport. It was possible to dissociate effects on mitochondria and lysosomes in these experiments; less streptolysin was necessary to damage lysosomes than mitochondria; the converse was found with vitamin A. Injury to mitochondria resulted from the direct action of these agents, since the lysosomal enzymes released as a consequence of their action were not capable of inducing mitochondrial swelling or release of enzymes under the conditions studied.
Topics: Animals; Ascorbic Acid; Bacterial Proteins; Cysteine; Electron Transport; Glucuronidase; Hemolytic Agents; Liver; Lysosomes; Magnesium; Malate Dehydrogenase; Mitochondria; Mitochondrial Swelling; Pharmacology; Phosphates; Rabbits; Research; Streptolysins; Thyroxine; Vitamin A
PubMed: 14195604
DOI: 10.1083/jcb.22.1.101 -
The Journal of General Physiology Oct 2020Mitochondrial permeability transition (PT) is a phenomenon of stress-induced increase in nonspecific permeability of the mitochondrial inner membrane that leads to...
Mitochondrial permeability transition (PT) is a phenomenon of stress-induced increase in nonspecific permeability of the mitochondrial inner membrane that leads to disruption of oxidative phosphorylation and cell death. Quantitative measurement of the membrane permeability increase during PT is critically important for understanding the PT's impact on mitochondrial function. The elementary unit of PT is a PT pore (PTP), a single channel presumably formed by either ATP synthase or adenine nucleotide translocator (ANT). It is not known how many channels are open in a single mitochondrion during PT, which makes it difficult to quantitatively estimate the overall degree of membrane permeability. Here, we used wide-field microscopy to record mitochondrial swelling and quantitatively measure rates of single-mitochondrion volume increase during PT-induced high-amplitude swelling. PT was quantified by calculating the rates of water flux responsible for measured volume changes. The total water flux through the mitochondrial membrane of a single mitochondrion during PT was in the range of (2.5 ± 0.4) × 10-17 kg/s for swelling in 2 mM Ca2+ and (1.1 ± 0.2) × 10-17 kg/s for swelling in 200 µM Ca2+. Under these experimental conditions, a single PTP channel with ionic conductance of 1.5 nS could allow passage of water at the rate of 0.65 × 10-17 kg/s. Thus, we estimate the integral ionic conductance of the whole mitochondrion during PT to be 5.9 ± 0.9 nS for 2 mM concentration of Ca2+ and 2.6 ± 0.4 nS for 200 µM of Ca2+. The number of PTPs per mitochondrion ranged from one to nine. Due to the uncertainties in PTP structure and model parameters, PTP count results may be slightly underestimated. However, taking into account that each mitochondrion has ∼15,000 copies of ATP synthases and ANTs, our data imply that PTP activation is a rare event that occurs only in a small subpopulation of these proteins.
Topics: Calcium; Cell Membrane Permeability; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Swelling
PubMed: 32810269
DOI: 10.1085/jgp.202012631