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The Biochemical Journal Sep 1993The ability of O2 metabolites derived from the xanthine-xanthine oxidase system to inhibit mitochondrial function was examined using freshly isolated rat liver...
The ability of O2 metabolites derived from the xanthine-xanthine oxidase system to inhibit mitochondrial function was examined using freshly isolated rat liver mitochondria. Under 2,4-dinitrophenol-uncoupled conditions, mitochondria exposed to free radicals exhibited a significant decrease in O2 consumption supported by NAD(+)-linked substrates, but showed almost no change in O2 consumption in the presence of succinate and ascorbate. Oxidative stress caused the loss of intramitochondrial nicotinamide nucleotides, and addition of NAD+ fully prevented any fall in O2 consumption with NAD(+)-linked substrates. The activity of electron-transfer complex I (NADH oxidase and NADH-cytochrome c oxidoreductase) and the energy-dependent reduction of NAD+ by succinate were unaltered by oxidative stress. Exposure to free radicals also had an uncoupling effect at all three coupling sites. The degree of mitochondrial swelling was closely correlated with the inhibition of State-3 oxidation of site-I substrates and with the increase in State-4 oxidation of succinate. The immunosuppressive agent cyclosporin A completely prevented the mitochondrial damage induced by oxygen free radicals (swelling, Ca2+ release, sucrose trapping, uncoupling and selective inhibition of the mitochondrial respiration of site-I substrates). The same protective effect was found when Ca2+ cycling was prevented, either by chelating Ca2+ with EGTA or by inhibiting Ca2+ reuptake with Ruthenium Red. These findings suggest that the deleterious effect of free radicals on mitochondria in the present experimental system was triggered by the cyclosporin A-sensitive and Ca(2+)-dependent membrane transition, and not by direct impairment of the mitochondrial inner-membrane enzymes.
Topics: Adenosine Triphosphate; Animals; Calcium; Cyclosporine; Electron Transport; In Vitro Techniques; Intracellular Membranes; Male; Mitochondria, Liver; Mitochondrial Swelling; NAD; Oxygen Consumption; Permeability; Rats; Rats, Wistar; Reactive Oxygen Species; Ruthenium Red
PubMed: 7691056
DOI: 10.1042/bj2940719 -
Experimental Neurology Aug 2009Caspase-independent cell death, an important death pathway in many cells including neurons, is executed via apoptosis-inducing factor (AIF), an oxidoreductase, localized...
Caspase-independent cell death, an important death pathway in many cells including neurons, is executed via apoptosis-inducing factor (AIF), an oxidoreductase, localized to the mitochondrial intermembrane space. AIF is processed and released from mitochondria following mitochondrial permeability transition pore (mPTP) formation, and translocates to the nucleus to induce DNA fragmentation and cell death. The release of AIF requires cleavage of its N-terminus anchored in the inner mitochondrial membrane. The protease responsible for this AIF truncation has not been established, although there is considerable evidence suggesting a role for micro-calpain. We previously found that a pool of micro-calpain is localized to the mitochondrial intermembrane space, the submitochondrial compartment in which AIF truncation occurs. The close submitochondrial proximity of mitochondrial micro-calpain and AIF gives support to the hypothesis that mitochondrial micro-calpain may be the protease responsible for processing AIF prior to its release. In the present study, AIF was released from rat liver mitochondria following mPTP induction by atractyloside. This release was inhibited by the cysteine protease inhibitor MDL28170, but not by more specific calpain inhibitors PD150606 and calpastatin. Atractyloside caused swelling in rat brain mitochondria, but did not induce AIF release. In a mitochondrial fraction from SH-SY5Y neuroblastoma cells, incubation with 5 mM Ca(2+) resulted in the activation of micro-calpain but not in AIF truncation. In summary, the localization of micro-calpain to the mitochondrial intermembrane space is suggestive of its possible involvement in AIF processing, but direct experimental evidence supporting such a role has been elusive.
Topics: Acrylates; Animals; Apoptosis Inducing Factor; Atractyloside; Blotting, Western; Calcium; Calcium-Binding Proteins; Calpain; Cell Line, Tumor; Cerebral Cortex; Cysteine Proteinase Inhibitors; Dipeptides; Enzyme Inhibitors; Liver; Male; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Rats; Rats, Sprague-Dawley
PubMed: 19393648
DOI: 10.1016/j.expneurol.2009.04.013 -
Basic & Clinical Pharmacology &... Sep 2016Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death. In patients for whom HCC could not be detected early, current treatments show poor...
Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death. In patients for whom HCC could not be detected early, current treatments show poor tolerance and low efficacy. So, alternative therapies with good efficacy are urgently needed. The aim of this research was to evaluate the selective apoptotic effects of myricetin (MYR), a flavonoid compound, on hepatocytes and mitochondria obtained from the liver of HCC rats. In this study, HCC induced by diethylnitrosamine (DEN), as an initiator, and 2-acetylaminofluorene (2-AAF), as a promoter. To confirm the HCC induction, serum levels of alpha-fetoprotein (AFP), AST, AST and ALP and histopathological changes in the liver tissue were evaluated. Rat liver hepatocytes and mitochondria for evaluation of the selective cytotoxic effects of MYR were isolated, and mitochondrial and cellular parameters related to apoptosis signalling were then determined. Our results showed that MYR was able to induce cytotoxicity only in hepatocytes from the HCC but not from the untreated control group. Besides, MYR (12.5, 25 and 50 μM) induced a considerable increase in reactive oxygen species (ROS) level, mitochondrial swelling, mitochondrial membrane permeabilization (MMP) and cytochrome c release only in cancerous but not in untreated normal hepatocyte mitochondria. MYR selectively increased caspase-3 activation and apoptotic phenotypes in HCC, but not untreated normal hepatocytes. Finally, our finding underlines MYR as a promising therapeutic candidate against HCC and recommends the compound for further studies.
Topics: 2-Acetylaminofluorene; Alanine Transaminase; Alkaline Phosphatase; Animals; Apoptosis; Aspartate Aminotransferases; Carcinoma, Hepatocellular; Caspase 3; Cytochromes c; Diethylnitrosamine; Disease Models, Animal; Flavonoids; Hepatocytes; Liver; Liver Neoplasms; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Swelling; Organ Size; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; alpha-Fetoproteins
PubMed: 26919160
DOI: 10.1111/bcpt.12572 -
Genetics Oct 2005Little is known about the regulation of ion transport across the inner mitochondrial membrane in Saccharomyces cerevisiae. To approach this problem, we devised a... (Comparative Study)
Comparative Study
Little is known about the regulation of ion transport across the inner mitochondrial membrane in Saccharomyces cerevisiae. To approach this problem, we devised a screening procedure for facilitating the identification of proteins involved in mitochondrial ion homeostasis. Taking advantage of the growth inhibition of yeast cells by electroneutral K(+)/H(+) ionophore nigericin, we screened for genetic mutations that would render cells tolerant to this drug when grown on a nonfermentable carbon source and identified several candidate genes including MDM31, MDM32, NDI1, YMR088C (VBA1), CSR2, RSA1, YLR024C, and YNL136W (EAF7). Direct examination of intact cells by electron microscopy indicated that mutants lacking MDM31 and/or MDM32 genes contain dramatically enlarged, spherical mitochondria and that these morphological abnormalities can be alleviated by nigericin. Mitochondria isolated from the Deltamdm31 and Deltamdm32 mutants exhibited limited swelling in an isotonic solution of potassium acetate even in the presence of an exogenous K(+)/H(+) antiport. In addition, growth of the mutants was inhibited on ethanol-containing media in the presence of high concentrations of salts (KCl, NaCl, or MgSO(4)) and their mitochondria exhibited two- (Deltamdm31 and Deltamdm32) to threefold (Deltamdm31Deltamdm32) elevation in magnesium content. Taken together, these data indicate that Mdm31p and Mdm32p control mitochondrial morphology through regulation of mitochondrial cation homeostasis and the maintenance of proper matrix osmolarity.
Topics: Cations; DNA Primers; Membrane Proteins; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Mitochondria; Mitochondrial Proteins; Mitochondrial Swelling; Mutation; Nigericin; Oxygen Consumption; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
PubMed: 16020778
DOI: 10.1534/genetics.105.046540 -
British Journal of Pharmacology Jul 2005Antidiabetic sulphonylureas can bind to various intracellular organelles including mitochondria. The aim of this study was to monitor the influence of antidiabetic...
Antidiabetic sulphonylureas can bind to various intracellular organelles including mitochondria. The aim of this study was to monitor the influence of antidiabetic sulphonylureas on membrane permeability in mitochondria isolated from rat skeletal muscle. The effects of glibenclamide (and other sulphonylurea derivatives) on mitochondrial function were studied by measuring mitochondrial swelling, mitochondrial membrane potential, respiration rate and Ca2+ transport into mitochondria. We observed that glibenclamide induced mitochondrial swelling (EC50 = 8.2 +/- 2.5 microM), decreased the mitochondrial membrane potential and evoked Ca2+ efflux from the mitochondrial matrix. These effects were blocked by 2 microM cyclosporin A, an inhibitor of the mitochondrial permeability transition. Moreover, 30 microM glibenclamide accelerated the respiratory rate in the presence of glutamate/malate, substrates of complex I of the mitochondrial respiratory chain. In conclusion, we postulate that the antidiabetic sulphonylureas activate the mitochondrial permeability transition in skeletal muscle by increasing its sensitivity to Ca2+.
Topics: Animals; Calcium; Cyclosporine; Glipizide; Glyburide; Hypoglycemic Agents; In Vitro Techniques; Membrane Potentials; Mitochondria, Muscle; Mitochondrial Swelling; Muscle, Skeletal; Oxygen; Permeability; Rats; Sulfonylurea Compounds
PubMed: 15895111
DOI: 10.1038/sj.bjp.0706214 -
Infection and Immunity Oct 1974The mechanism of a synergistic toxicity of 6,6'-dimycoloyl-alpha,alpha'-d-trehalose (cord factor) and 2,3,6,6'-tetraacyl-alpha,alpha'-d-trehalose 2'-sulfate (sulfolipid...
The mechanism of a synergistic toxicity of 6,6'-dimycoloyl-alpha,alpha'-d-trehalose (cord factor) and 2,3,6,6'-tetraacyl-alpha,alpha'-d-trehalose 2'-sulfate (sulfolipid I) for mice was studied. Sulfolipid I was entirely nontoxic, but it markedly accelerated the lethal toxicity of cord factor for mice. In vivo, sulfolipid I affected neither respiration nor accompanying phosphorylation of mouse liver mitochondria, whereas in vitro, it induced a swelling and disruption of mitochondrial membranes and strongly inhibited mitochondrial oxidative phosphorylation. The effect of sulfolipid I on mitochondrial structure and function in vitro was neutralized by bovine serum albumin and various animal sera, whereas that of cord factor and cord factor plus sulfolipid I was not prevented by bovine serum albumin. The simultaneous injection of cord factor and sulfolipid I caused an intensive fragmentation of mitochondria and a marked decrease in respiratory and phosphorylative activity in mitochondria. These data indicate that sulfolipid I can achieve an effective attack on mitochondria in combination with cord factor in vivo and induces heavier damage in mitochondrial structure and function than that produced by cord factor alone.
Topics: Animals; Disaccharides; Dose-Response Relationship, Drug; Drug Synergism; Glycolipids; Male; Mice; Mitochondria, Liver; Mitochondrial Swelling; Mycobacterium tuberculosis; Oxidative Phosphorylation; Serum Albumin, Bovine; Sulfuric Acids; Trehalose
PubMed: 4214779
DOI: 10.1128/iai.10.4.733-741.1974 -
World Journal of Gastroenterology Jun 2005To investigate the anti-lipid peroxidation and protection of liver mitochondria against injuries in mice with liver damage by picroside II.
AIM
To investigate the anti-lipid peroxidation and protection of liver mitochondria against injuries in mice with liver damage by picroside II.
METHODS
Three animal models of liver damage induced by carbon tetrachloride (CCl(4): 0.1 mL/10 g, ip), D-galactosamine (D-GalN: 500 mg/kg, ip) and acetaminophen (AP: 0.15 g/kg, ip) were respectively treated with various concentrations of picroside II (5, 10, 20 mg/kg, ig). Then we chose the continuously monitoring method (recommended by International Clinical Chemistry League) to analyze serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values, Marland method to detect the activity of manganese-superoxide dismutase (SOD) in liver mitochondria, TBA colorimetry to determine the content of malonicdialdehyde (MDA) in liver tissue, DTNB method to evaluate the activity of glutathioneperoxidase (GSH-Px) and Lowry method to detect protein level in liver tissue. Meanwhile, effects of picroside II on the activity of ATPase and swelling extent of mitochondria in hepatocytes damaged by AP were also evaluated.
RESULTS
Picroside II could significantly prevent liver toxicity in the three models of liver damage. It decreased the high levels of ALT and AST in serum induced by the administration of CCl(4), D-GalN and AP, reduced the cellular damage of liver markedly, and appeared to be even more potent than the positive control drug of biphenyl dimethyl dicarboxylate pilules (DDB). In groups treated with different doses of picroside II, compared to the model group, the content of MDA in serum decreased evidently, whereas the content of SOD and GSH-Px increased in a dose-dependent manner, and the difference was statistically significant. Further, in the study of AP model, picroside II inhibited AP-induced liver toxicity in mice, enhanced the activity of ATPase, improved the swelling extent of mitochondria and helped to maintain a normal balance of energy metabolism.
CONCLUSION
Picroside II can evidently relieve hepatocyte injuries induced by CCl(4), D-GalN and AP, help scavenge free radicals, protect normal constructions of mitochondria membrane and enhance the activity of ATPase in mitochondria, thereby modulating the balance of liver energy metabolism, which might be part of the mechanisms of hepatoprotective effects of picroside II.
Topics: Animals; Carbon Tetrachloride; Chemical and Drug Induced Liver Injury; Cinnamates; Disease Models, Animal; Female; Glucosides; Iridoid Glucosides; Lipid Peroxidation; Male; Mice; Mice, Inbred Strains; Mitochondria, Liver; Mitochondrial Swelling
PubMed: 15968718
DOI: 10.3748/wjg.v11.i24.3671 -
Cell Calcium Jul 2009Cultured hippocampal neurons expressing mitochondrially-targeted enhanced yellow fluorescent protein (mito-eYFP) were used to quantitatively examine mitochondrial...
Cultured hippocampal neurons expressing mitochondrially-targeted enhanced yellow fluorescent protein (mito-eYFP) were used to quantitatively examine mitochondrial remodelling in response to excitotoxic glutamate. Mitochondrial morphology was evaluated using laser spinning-disk confocal microscopy followed by calibrated image processing and 3D image rendering. Glutamate triggered an increase in cytosolic Ca(2+) and mitochondrial depolarization accompanied by Ca(2+)-dependent morphological transformation of neuronal mitochondria from "thread-like" to rounded structures. The quantitative analysis of the mitochondrial remodelling revealed that exposure to glutamate resulted in a decrease in mitochondrial volume and surface area concurrent with an increase in sphericity of the organelles. NIM811, an inhibitor of the mitochondrial permeability transition, attenuated the glutamate-induced sustained increase in cytosolic Ca(2+) and suppressed mitochondrial remodelling in the majority of affected neurons, but it did not rescue mitochondrial membrane potential. Shortening, fragmentation, and formation of circular mitochondria with decreased volume and surface area accompanied mitochondrial depolarization with FCCP. However, FCCP-induced morphological alterations appeared to be distinctly different from mitochondrial remodelling caused by glutamate. Moreover, FCCP prevented glutamate-induced mitochondrial remodelling suggesting an important role of Ca(2+) influx into mitochondria in the morphological alterations. Consistent with this, in saponin-permeabilized neurons, Ca(2+) caused mitochondrial remodelling which could be prevented by Ru(360).
Topics: Animals; Calcium; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Cells, Cultured; Glutamic Acid; Green Fluorescent Proteins; Hippocampus; Light; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Neurons; Permeability; Rats; Receptors, Glutamate; Ruthenium Compounds; Valinomycin
PubMed: 19409612
DOI: 10.1016/j.ceca.2009.03.017 -
The Journal of Neuroscience : the... Jul 1998Induction of the mitochondrial permeability transition (MPT) has been implicated in cellular apoptosis and in ischemia-reperfusion injury. During MPT, a channel in the...
Induction of the mitochondrial permeability transition (MPT) has been implicated in cellular apoptosis and in ischemia-reperfusion injury. During MPT, a channel in the inner mitochondrial membrane, the mitochondrial megachannel, opens and causes isolated mitochondria to swell. MPT and mitochondrial swelling is inhibited by cyclosporin A (CsA), which may also inhibit apoptosis in some cells. Treatment with CsA (50 mg/kg, i.v.) showed a robust reduction of brain damage when administered 30 min before insulin-induced hypoglycemic isoelectricity of 30 min duration. Ultrastructural examination of the dentate gyrus revealed a marked swelling of dendrites and mitochondria during the hypoglycemic insult. In CsA-treated animals, mitochondria resumed a normal and contracted appearance during and after the hypoglycemic insult. Treatment with FK 506 (2 mg/kg, i.v.), a compound with immunosuppressive action similar to that of CsA, was not protective. Studies on the swelling kinetics of isolated mitochondria from the hippocampus showed that CsA, but not FK 506, inhibits calcium ion-induced MPT. We conclude that CsA treatment during hypoglycemic coma inhibits the MPT and reduces damage and that mitochondria and the MPT are likely to be involved in the development of hypoglycemic brain damage in the rat.
Topics: Animals; Cell Death; Cell Respiration; Cyclosporine; Drug Evaluation, Preclinical; Hippocampus; Hypoglycemia; Immunosuppressive Agents; Male; Mitochondria; Mitochondrial Swelling; Neurons; Permeability; Rats; Rats, Wistar; Tacrolimus
PubMed: 9651198
DOI: 10.1523/JNEUROSCI.18-14-05151.1998 -
Bioscience Reports May 2020Amino acid sequence from 65th to 76th residue of the N-terminus of Chromogranin A (CGA-N12) is an antimicrobial peptide (AMP). Our previous studies showed that CGA-N12...
Amino acid sequence from 65th to 76th residue of the N-terminus of Chromogranin A (CGA-N12) is an antimicrobial peptide (AMP). Our previous studies showed that CGA-N12 reduces Candida tropicalis mitochondrial membrane potential. Here, we explored the mechanism that CGA-N12 collapsed the mitochondrial membrane potential by investigations of its action on the mitochondrial permeability transition pore (mPTP) complex of C. tropicalis. The results showed that CGA-N12 induced cytochrome c (Cyt c) leakage, mitochondria swelling and led to polyethylene glycol (PEG) of molecular weight 1000 Da penetrate mitochondria. mPTP opening inhibitors bongkrekic acid (BA) could contract the mitochondrial swelling induced by CGA-N12, but cyclosporin A (CsA) could not. Therefore, we speculated that CGA-N12 could induce C. tropicolis mPTP opening by preventing the matrix-facing (m) conformation of adenine nucleotide transporter (ANT), thereby increasing the permeability of the mitochondrial membrane and resulted in the mitochondrial potential dissipation.
Topics: Antifungal Agents; Candida tropicalis; Chromogranin A; Cytochromes c; Fungal Proteins; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial ADP, ATP Translocases; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Peptide Fragments; Pore Forming Cytotoxic Proteins
PubMed: 32368781
DOI: 10.1042/BSR20201007