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Journal of Neurochemistry Feb 2014Zinc has been implicated in neurodegeneration following ischemia. In analogy with calcium, zinc has been proposed to induce toxicity via mitochondrial dysfunction, but...
Zinc has been implicated in neurodegeneration following ischemia. In analogy with calcium, zinc has been proposed to induce toxicity via mitochondrial dysfunction, but the relative role of each cation in mitochondrial damage remains unclear. Here, we report that under conditions mimicking ischemia in hippocampal neurons - normal (2 mM) calcium plus elevated (> 100 μM) exogenous zinc - mitochondrial dysfunction evoked by glutamate, kainate or direct depolarization is, despite significant zinc uptake, primarily governed by calcium. Thus, robust mitochondrial ion accumulation, swelling, depolarization, and reactive oxygen species generation were only observed after toxic stimulation in calcium-containing media. This contrasts with the lack of any mitochondrial response in zinc-containing but calcium-free medium, even though zinc uptake and toxicity were strong under these conditions. Indeed, abnormally high, ionophore-induced zinc uptake was necessary to elicit any mitochondrial depolarization. In calcium- and zinc-containing media, depolarization-induced zinc uptake facilitated cell death and enhanced accumulation of mitochondrial calcium, which localized to characteristic matrix precipitates. Some of these contained detectable amounts of zinc. Together these data indicate that zinc uptake is generally insufficient to trigger mitochondrial dysfunction, so that mechanism(s) of zinc toxicity must be different from that of calcium.
Topics: Animals; Brain Ischemia; Calcium; Calcium Channels; Cells, Cultured; Cytosol; Electron Probe Microanalysis; Electrophysiological Phenomena; Female; Hippocampus; Indicators and Reagents; Microscopy, Electron; Microscopy, Fluorescence; Mitochondrial Diseases; Mitochondrial Swelling; Neurodegenerative Diseases; Pregnancy; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptors, AMPA; Zinc
PubMed: 24127746
DOI: 10.1111/jnc.12489 -
IUBMB Life 2001Electron tomography indicates that the mitochondrial inner membrane is not normally comprised of baffle-like folds as depicted in textbooks. In actuality, this membrane... (Review)
Review
Electron tomography indicates that the mitochondrial inner membrane is not normally comprised of baffle-like folds as depicted in textbooks. In actuality, this membrane is pleomorphic, with narrow tubular regions connecting the internal compartments (cristae) to each other and to the membrane periphery. The membrane topologies observed in condensed (matrix contracted) and orthodox (matrix expanded) mitochondria cannot be interconverted by passive folding and unfolding. Instead, transitions between these morphological states likely involve membrane fusion and fission. Formation of tubular junctions in the inner membrane appears to be energetically favored, because they form spontaneously in yeast mitochondria following large-amplitude swelling and recontraction. However, aberrant, unattached, vesicular cristae are also observed in these mitochondria, suggesting that formation of cristae junctions depends on factors (such as the distribution of key proteins and/or lipids) that are disrupted during extreme swelling. Computer modeling studies using the "Virtual Cell" program suggest that the shape of the inner membrane can influence mitochondrial function. Simulations indicate that narrow cristae junctions restrict diffusion between intracristal and external compartments, causing depletion of ADP and decreased ATP output inside the cristae.
Topics: Animals; Energy Metabolism; Humans; Imaging, Three-Dimensional; Intracellular Membranes; Membrane Fusion; Mitochondria; Mitochondrial Swelling; Tomography, X-Ray Computed
PubMed: 11798041
DOI: 10.1080/15216540152845885 -
The American Journal of Pathology Feb 1974Studies of mitochondrial respiratory control and swelling contraction activity during early cell regeneration after partial hepatectomy have revealed a selective defect...
Studies of mitochondrial respiratory control and swelling contraction activity during early cell regeneration after partial hepatectomy have revealed a selective defect in the rate of substrate-supported, phosphate-induced mitochondrial swelling. Swelling profiles induced by Fe(2-) or Cu(2-) revealed no differences between sham-operated and partially hepatectomized mice, which suggests no defects in -SH group composition or ability to form lipid peroxides. The specific activity of mitochondrial cytochrome c oxidase was unchanged. There was no significant mitochondrial swelling in situ as determined from mitocrit and mitochondrial protein ratios. A significant decline in respiratory control and efficiency of oxidative phosphorylation was found in mitochondria from animals 8 and 24 hours after partial hepatectomy, partially reversed by bovine serum albumin. No significant change in ADP:O ratio was noted and the decrease in RCI was due primarily to a significant decline in state 3 respiration rate. In situ electron microscopic studies of mitochondria failed to reveal significant abnormalities during early cell regeneration apart from decrease in numbers of matrix granules, focal matrix rarefaction and predominance of round forms. Electron microscopic studies of mitochondria after in vitro phosphate-induced swelling experiments showed no differences between sham and partially hepatectomized animals, but revealed two distinct populations of mitochondria, the predominant form (type III) showing distortion, matrix lucency and outer membrane rupture. ATP induced a diminished reversal in light scattering in partially hepatectomized mitochondria even when examined at 20 minutes, manifested as an increase in numbers of orthodox mitochondrial forms at the expense of the swollen type III forms. The pathogenesis of the impaired respiratory control and phosphate-induced swelling is unknown, but analogous observations have been found in mitochondria harvested from cells in which abnormal accumulations of free fatty acids have been demonstrated.
Topics: Adenosine Triphosphate; Animals; Copper; Cytoplasmic Granules; Electron Transport Complex IV; Hepatectomy; Iron; Liver Regeneration; Male; Mice; Microscopy, Electron; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Oxidative Phosphorylation; Oxygen Consumption; Phosphates; Time Factors
PubMed: 4359731
DOI: No ID Found -
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 -
Experimental Physiology Oct 2013The significance of the reduction of the cholesterol pool in heart mitochondria after exercise is still unknown. Recently, published data have suggested that cholesterol...
The significance of the reduction of the cholesterol pool in heart mitochondria after exercise is still unknown. Recently, published data have suggested that cholesterol may influence the components of mitochondrial contact site and affect mitochondrial swelling. Therefore, the aim of this study was to determine whether the decreased cholesterol content in heart mitochondria caused by prolonged swimming may provoke changes in their bioenergetics and result in an increased resistance to calcium chloride-induced mitochondrial swelling. Male Wistar rats were divided into a sedentary control group and an exercise group. The rats exercised for 3 h, burdened with an additional 3% of their body weight. Their hearts were removed immediately after completing the exercise. The left ventricle was divided and used for experiments. Mitochondrial cholesterol content, membrane fluidity and mitochondrial bioenergetics were measured in the control and exercised rat heart mitochondria. To assess whether mitochondrial modifications are linked to disruption of lipid microdomains, methyl-β-cyclodextrin, a well-known lipid microdomain-disrupting agent and cholesterol chelator, was applied to the mitochondria of the control group. Cholesterol depletion, increased membrane fluidity and increased resistance to calcium chloride-induced swelling were observed in postexercise heart crude mitochondrial fraction. Similar results were achieved in control mitochondria treated with 2% methyl-β-cyclodextrin. All of the mitochondrial bioenergetics parameters were similar between the groups. Therefore, the disruption of raft-like microdomains appears to be an adaptive change in the rat heart following exercise.
Topics: Animals; Calcium Chloride; Cholesterol; Lactic Acid; Male; Membrane Fluidity; Mitochondria, Heart; Mitochondrial Swelling; Oxidative Stress; Physical Conditioning, Animal; Rats; Rats, Wistar; Swimming
PubMed: 23733522
DOI: 10.1113/expphysiol.2013.073007 -
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 Sep 1999Mitochondria are involved in cell death for reasons that go beyond ATP supply. A recent advance has been the discovery that mitochondria contain and release proteins... (Review)
Review
Mitochondria are involved in cell death for reasons that go beyond ATP supply. A recent advance has been the discovery that mitochondria contain and release proteins that are involved in the apoptotic cascade, like cytochrome c and apoptosis inducing factor. The involvement of mitochondria in cell death, and its being cause or consequence, remain issues that are extremely complex to address in situ. The response of mitochondria may critically depend on the type of stimulus, on its intensity, and on the specific mitochondrial function that has been primarily perturbed. On the other hand, the outcome also depends on the integration of mitochondrial responses that cannot be dissected easily. Here, we try to identify the mechanistic aspects of mitochondrial involvement in cell death as can be derived from our current understanding of mitochondrial physiology, with special emphasis on the permeability transition and its consequences (like onset of swelling, cytochrome c release and respiratory inhibition); and to critically evaluate methods that are widely used to monitor mitochondrial function in situ.
Topics: Animals; Apoptosis; Apoptosis Inducing Factor; Calcium; Cell Death; Cytochrome c Group; Flavoproteins; Humans; Ion Transport; Membrane Potentials; Membrane Proteins; Mitochondria; Mitochondrial Swelling; Necrosis; Permeability; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; bcl-2-Associated X Protein
PubMed: 10491114
DOI: 10.1046/j.1432-1327.1999.00725.x -
Disease Models & Mechanisms Aug 2019A dopamine D2 receptor agonist, pramipexole, has been found to elicit neuroprotection in patients with Parkinson's disease and restless leg syndrome. Recent evidence has...
A dopamine D2 receptor agonist, pramipexole, has been found to elicit neuroprotection in patients with Parkinson's disease and restless leg syndrome. Recent evidence has shown that pramipexole mediates its neuroprotection through mitochondria. Considering this, we examined the possible mitochondrial role of pramipexole in promoting neuroprotection following an ischemic stroke of rat. Male Wistar rats underwent transient middle cerebral artery occlusion (tMCAO) and then received pramipexole (0.25 mg and 1 mg/kg body weight) at 1, 6, 12 and 18 h post-occlusion. A panel of neurological tests and 2,3,5-triphenyl tetrazolium chloride (TTC) staining were performed at 24 h after the surgery. Flow cytometry was used to detect the mitochondrial membrane potential, and mitochondrial levels of reactive oxygen species (ROS) and Ca, respectively. Mitochondrial oxidative phosphorylation was analyzed by oxygraph (oxygen electrode). Western blotting was used to analyze the expression of various proteins such as Bax, Bcl-2 and cytochrome Pramipexole promoted the neurological recovery as shown by the panel of neurobehavioral tests and TTC staining. Post-stroke treatment with pramipexole reduced levels of mitochondrial ROS and Ca after ischemia. Pramipexole elevated the mitochondrial membrane potential and mitochondrial oxidative phosphorylation. Western blotting showed that pramipexole inhibited the transfer of cytochrome from mitochondria to cytosol, and hence inhibited the mitochondrial permeability transition pore. Thus, our results have demonstrated that post-stroke administration of pramipexole induces the neurological recovery through mitochondrial pathways in ischemia/reperfusion injury.
Topics: Animals; Brain Ischemia; Calcium; Cell Death; Cytochromes c; Down-Regulation; Energy Metabolism; Hand Strength; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Swelling; Motor Activity; Oxygen Consumption; Pramipexole; Rats, Wistar; Reactive Oxygen Species; Recovery of Function; Signal Transduction; Stroke; bcl-2-Associated X Protein
PubMed: 31235613
DOI: 10.1242/dmm.033860 -
Oxidative Medicine and Cellular... 2016The reduction in cholesterol in mitochondria, observed after exercise, is related to the inhibition of mitochondrial swelling. Caveolin-1 (Cav-1) plays an essential role...
The reduction in cholesterol in mitochondria, observed after exercise, is related to the inhibition of mitochondrial swelling. Caveolin-1 (Cav-1) plays an essential role in the regulation of cellular cholesterol metabolism and is required by various signalling pathways. Therefore, the aim of this study was to investigate the effect of prolonged swimming on the mitochondrial Cav-1 concentration; additionally, we identified the results of these changes as they relate to the induction of changes in the mitochondrial swelling and cholesterol in rat skeletal muscle and liver. Male Wistar rats were divided into a sedentary control group and an exercise group. The exercised rats swam for 3 hours and were burdened with an additional 3% of their body weight. After the cessation of exercise, their quadriceps femoris muscles and livers were immediately removed for experimentation. The exercise protocol caused an increase in the Cav-1 concentration in crude muscle mitochondria; this was related to a reduction in the cholesterol level and an inhibition of mitochondrial swelling. There were no changes in rat livers, with the exception of increased markers of oxidative stress in mitochondria. These data indicate the possible role of Cav-1 in the adaptive change in the rat muscle mitochondria following exercise.
Topics: Animals; Body Weight; Caveolin 1; Cholesterol; Liver; Male; Mitochondria; Mitochondrial Swelling; Muscle, Skeletal; Oxidative Stress; Physical Conditioning, Animal; Quadriceps Muscle; Rats; Rats, Wistar; Reactive Oxygen Species; Sedentary Behavior; Signal Transduction; Swimming
PubMed: 26839631
DOI: 10.1155/2016/3620929 -
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