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NAD(H) Regulates the Permeability Transition Pore in Mitochondria through an External Site. Int J Mol Sci 2021; 22:ijms22168560. [PMID: 34445270 PMCID: PMC8395297 DOI: 10.3390/ijms22168560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/28/2021] [Accepted: 08/05/2021] [Indexed: 11/17/2022] Open
Abstract
The opening of the permeability transition pore (mPTP) in mitochondria initiates cell death in numerous diseases. The regulation of mPTP by NAD(H) in the mitochondrial matrix is well established; however, the role of extramitochondrial (cytosolic) NAD(H) is still unclear. We studied the effect of added NADH and NAD+ on: (1) the Ca2+-retention capacity (CRC) of isolated rat liver, heart, and brain mitochondria; (2) the Ca2+-dependent mitochondrial swelling in media whose particles can (KCl) or cannot (sucrose) be extruded from the matrix by mitochondrial carriers; (3) the Ca2+-dependent mitochondrial depolarization and the release of entrapped calcein from mitochondria of permeabilized hepatocytes; and (4) the Ca2+-dependent mitochondrial depolarization and subsequent repolarization. NADH and NAD+ increased the CRC of liver, heart, and brain mitochondria 1.5-2.5 times, insignificantly affecting the rate of Ca2+-uptake and the free Ca2+ concentration in the medium. NAD(H) suppressed the Ca2+-dependent mitochondrial swelling both in KCl- and sucrose-based media but did not induce the contraction and repolarization of swollen mitochondria. By contrast, EGTA caused mitochondrial repolarization in both media and the contraction in KCl-based medium only. NAD(H) delayed the Ca2+-dependent depolarization and the release of calcein from individual mitochondria in hepatocytes. These data unambiguously demonstrate the existence of an external NAD(H)-dependent site of mPTP regulation.
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Kruglov AG, Kharechkina ES, Nikiforova AB, Odinokova IV, Kruglova SA. Dynamics of the permeability transition pore size in isolated mitochondria and mitoplasts. FASEB J 2021; 35:e21764. [PMID: 34245631 DOI: 10.1096/fj.202100596r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/28/2021] [Accepted: 06/14/2021] [Indexed: 11/11/2022]
Abstract
The size of the permeability transition pore (PTP) is accepted to be ≤1.5 kDa. However, different authors reported values from 650 to 4000 Da. The present study is focused on the variability of the average PTP size in and between mitochondrial samples, its reasons and relations with PTP dynamics. Measurement of PTP size by the standard method revealed its 500 Da-range variability between mitochondrial samples. Sequential measurements in the same sample showed that the PTP size tends to grow with time and Ca2+ concentration. Selective damage to the mitochondrial outer membrane (MOM) reduced the apparent PTP size by ~200-300 Da. Hypotonic and hypertonic osmotic shock and partial removal of the MOM with the preservation of the mitochondrial inner membrane intactness decreased the apparent PTP size by ~50%. We developed an approach to continuous monitoring of the PTP size that revealed the existence of stable PTP states with different pore sizes (~700, 900-1000, ~1350, 1700-1800, and 2100-2200 Da) and transitions between them. The transitions were accelerated by elevating the Ca2+ concentration, temperature, and osmotic pressure, which demonstrates an increased capability of PTP to accommodate to large molecules (plasticity). Cyclosporin A inhibited the transitions between states. The analysis of PTP size dynamics in osmotically shocked mitochondria and mitoplasts confirmed the importance of the MOM for the stabilization of PTP structure. Thus, this approach provides a new tool for PTP studies and the opportunity to reconcile data on the PTP size and mitochondrial megachannel conductance.
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Affiliation(s)
- Alexey G Kruglov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Ekaterina S Kharechkina
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Anna B Nikiforova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Irina V Odinokova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Svetlana A Kruglova
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Russia
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Sassi N, Mattarei A, Azzolini M, Szabo' I, Paradisi C, Zoratti M, Biasutto L. Cytotoxicity of mitochondria-targeted resveratrol derivatives: Interactions with respiratory chain complexes and ATP synthase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1781-9. [DOI: 10.1016/j.bbabio.2014.06.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 06/13/2014] [Accepted: 06/27/2014] [Indexed: 02/06/2023]
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Monteiro JP, Silva AM, Jurado AS, Oliveira PJ. Rapeseed oil-rich diet alters in vitro menadione and nimesulide hepatic mitochondrial toxicity. Food Chem Toxicol 2013; 60:479-87. [DOI: 10.1016/j.fct.2013.07.073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 07/25/2013] [Accepted: 07/27/2013] [Indexed: 11/16/2022]
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5
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A biophysical approach to menadione membrane interactions: Relevance for menadione-induced mitochondria dysfunction and related deleterious/therapeutic effects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1899-908. [DOI: 10.1016/j.bbamem.2013.04.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 03/20/2013] [Accepted: 04/08/2013] [Indexed: 11/23/2022]
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6
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Okuda K, Hasui K, Abe M, Matsumoto K, Shindo M. Molecular Design, Synthesis, and Evaluation of Novel Potent Apoptosis Inhibitors Inspired from Bongkrekic Acid. Chem Res Toxicol 2012; 25:2253-60. [DOI: 10.1021/tx300315h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Katsuhiro Okuda
- Institute for Materials Chemistry
and Engineering, Kyushu University, 6-1
Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - Keisuke Hasui
- Interdisciplinary Graduate School
of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - Masato Abe
- Institute for Materials Chemistry
and Engineering, Kyushu University, 6-1
Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - Kenji Matsumoto
- Institute for Materials Chemistry
and Engineering, Kyushu University, 6-1
Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - Mitsuru Shindo
- Institute for Materials Chemistry
and Engineering, Kyushu University, 6-1
Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
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7
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Abstract
Tyrosine phosphorylation is a newcomer in the mitochondrial signaling and is currently emerging as an important mechanism for regulating mitochondrial processes. But to what extent? By analyzing an updated draft of the mitochondrial tyrosine phosphoproteome, the following observations can be drawn: more than a hundred mitochondrial proteins undergo tyrosine phosphorylation, phosphotyrosine proteins are distributed in each of the submitochondrial compartments, and mitochondrial tyrosine phosphorylated proteins are involved in a variety of functions as metabolism (electron transport chain, Krebs cycle, fatty acid and amino acid metabolism), solute and protein transport, mitochondrial translation machinery, quality protein assessment, oxidative stress, apoptosis, fission, and other. This large and varied collection suggests that tyrosine phosphorylation could be a widespread mechanism in modulating mitochondrial functions. Moreover the in silico model is here used to explore potential effects of tyrosine phosphorylation on selected mitochondrial proteins pointing out some future perspectives in this field.
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Affiliation(s)
- Luca Cesaro
- Department of Biological Chemistry, University of Padova, Viale G. Colombo 3, Padua, Italy
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8
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Azzu V, Brand MD. Degradation of an intramitochondrial protein by the cytosolic proteasome. J Cell Sci 2010; 123:578-85. [PMID: 20103532 DOI: 10.1242/jcs.060004] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial uncoupling protein 2 (UCP2) is implicated in a wide range of pathophysiological processes, including immunity and diabetes mellitus, but its rapid degradation remains uncharacterized. Using pharmacological proteasome inhibitors, immunoprecipitation, dominant negative ubiquitin mutants, [corrected] cellular fractionation and siRNA techniques, we demonstrate the involvement of the ubiquitin-proteasome system in the rapid degradation of UCP2. Importantly, we resolve the issue of whether intramitochondrial proteins can be degraded by the cytosolic proteasome by reconstituting a cell-free system that shows rapid proteasome-inhibitor-sensitive UCP2 degradation in isolated, energised mitochondria presented with an ATP regenerating system, ubiquitin and 26S proteasome fractions. These observations provide the first demonstration that a mitochondrial inner membrane protein is degraded by the cytosolic ubiquitin-proteasome system.
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Affiliation(s)
- Vian Azzu
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
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Fedotcheva NI, Kazakov RE, Kondrashova MN, Beloborodova NV. Toxic effects of microbial phenolic acids on the functions of mitochondria. Toxicol Lett 2008; 180:182-8. [PMID: 18634861 DOI: 10.1016/j.toxlet.2008.06.861] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 06/04/2008] [Accepted: 06/09/2008] [Indexed: 11/30/2022]
Abstract
Low-molecular-weight phenolic acids (PhAs) phenylacetate, phenyllactate, phenylpropionate, p-hydroxyphenyllactate, and p-hydroxyphenylacetate are essentially the products of the degradation of aromatic amino acids and polyphenols by the intestinal microflora. In sepsis, the concentrations of some of these acids in the blood increase tens of times. Assuming that these compounds can cause the mitochondrial dysfunction in sepsis, we examined their effects on respiration, the induction of pore opening, and the production of reactive oxygen species (ROS) in mitochondria. It was found that phenylpropionate and phenylacetate produce a more toxic effect on mitochondria than the other phenolic acids. At concentrations 0.01-0.1 mM they decreased the rate of oxidation of NAD-dependent substrates and activated the Ca2+- and menadione-induced opening of the cyclosporin A-sensitive pore and the production of ROS. The disturbances caused by these PhAs are similar to those observed in mitochondria in sepsis, and hence the rise in their level may be one of the causes of mitochondrial dysfunctions. Phenyllactate, p-hydroxyphenyllactate, and p-hydroxyphenylacetate inhibited the production of ROS and pore opening, acting as antioxidants. Thus, the ability of PhAs to affect the mitochondrial functions, as well as an increase in their concentrations in sepsis (the total concentration of these PhAs in the blood is close to 0.1 mM), suggests that PhAs can be directly involved in the development of mitochondrial failure.
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Affiliation(s)
- N I Fedotcheva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia.
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Lewandrowski U, Sickmann A, Cesaro L, Brunati AM, Toninello A, Salvi M. Identification of new tyrosine phosphorylated proteins in rat brain mitochondria. FEBS Lett 2008; 582:1104-10. [DOI: 10.1016/j.febslet.2008.02.077] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 02/12/2008] [Accepted: 02/29/2008] [Indexed: 01/12/2023]
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Kruglov AG, Subbotina KB, Saris NEL. Redox-cycling compounds can cause the permeabilization of mitochondrial membranes by mechanisms other than ROS production. Free Radic Biol Med 2008; 44:646-56. [PMID: 18053818 DOI: 10.1016/j.freeradbiomed.2007.10.049] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 10/11/2007] [Accepted: 10/28/2007] [Indexed: 10/22/2022]
Abstract
The participation of reactive oxygen species (ROS) in the regulation of mitochondrial permeability transition pore (mPTP) opening by the redox-cycling compounds menadione and lucigenin was explored. The level of ROS was modulated by antioxidants, anoxia, and switching the sites of the reduction of redox cyclers, the dehydrogenases of the inner and outer mitochondrial membranes. We found that the reduction of both lucigenin and menadione in the outer mitochondrial membrane caused a strong production of ROS. However, mPTP opening was accelerated only in the presence of the cationic acceptor lucigenin. The antioxidants and scavengers of ROS that considerably decreased the level of ROS in mitochondria did not prevent or delay the mPTP opening. If the transmembrane potential under anoxia was supported by exogenous ATP or ferricyanide, the permeabilization of mitochondrial membranes by menadione or lucigenin was the same as under normoxia or even more pronounced. Under anoxia, the lucigenin-dependent permeabilization of membranes was less sensitive to mPTP antagonists than under normoxia. We conclude that the opening of the mPTP by redox cyclers may be independent of ROS and is due to the direct oxidation of mitochondrial pyridine nucleotides by menadione and the modification of critical thiols of the mPTP by the cation radical of lucigenin.
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Affiliation(s)
- Alexey G Kruglov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya, 3, 142290 Pushchino, Moscow Region, Russia.
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12
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Lim PLK, Tan W, Latchoumycandane C, Mok WC, Khoo YM, Lee HS, Sattabongkot J, Beerheide W, Lim SG, Tan TMC, Boelsterli UA. Molecular and functional characterization of drug-metabolizing enzymes and transporter expression in the novel spontaneously immortalized human hepatocyte line HC-04. Toxicol In Vitro 2007; 21:1390-401. [PMID: 17590308 DOI: 10.1016/j.tiv.2007.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 03/20/2007] [Accepted: 05/02/2007] [Indexed: 02/02/2023]
Abstract
In toxicological research, immortalized human hepatocytes provide a useful alternative to primary hepatocytes because interindividual variability in the expression of drug-metabolizing enzymes and drug transporters can largely be eliminated. However, it is essential that the cell line retain the original phenotype. The purpose of this study was to characterize a novel spontaneously immortalized human hepatocyte cell line, HC-04, with respect to the transcript and functional protein expression profile for the major drug-metabolizing enzymes and transmembrane transporters. HC-04 cells retained hepatocyte-specific function including albumin production and ornithine transcarbamoylase and glucose-6-phosphatase activity. Most of the major CYP forms were expressed at basal levels and responsive to inducing agents. In particular, CYP3A4 was expressed abundantly, and HC-04 cells were able to metabolize the CYP3A4 probe, midazolam, at a rate similar to primary human hepatocytes. Furthermore, the major human sulfotransferase and UDP-glucuronosyltransferase forms, as well as members of the ABC and SLC transporter superfamilies, nuclear receptors, and hepatic transcription factors were also expressed. HC-04 cells readily responded to standard hepatotoxicants that are dependent on CYP-mediated bioactivation, while another, tumor-derived cell line remained refractory to the drug challenge. Collectively, HC-04 cells provide a reliable, stable, and reproducible model for biomechanistic studies in drug toxicology.
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Affiliation(s)
- Priscilla L K Lim
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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13
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Agostinelli E, Tempera G, Molinari A, Salvi M, Battaglia V, Toninello A, Arancia G. The physiological role of biogenic amines redox reactions in mitochondria. New perspectives in cancer therapy. Amino Acids 2007; 33:175-87. [PMID: 17390098 DOI: 10.1007/s00726-007-0510-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Accepted: 02/01/2007] [Indexed: 01/24/2023]
Abstract
In tumours, polyamines and amine oxidases increase as compared to normal tissues. Cytotoxicity induced by bovine serum amine oxidase (BSAO) and spermine is attributed to H2O2 and aldehydes produced by the reaction. Increasing the incubation temperature from 37 to 42 degrees C enhances cytotoxicity in cells exposed to spermine metabolites. The combination BSAO/spermine prevents tumour growth, particularly well if the enzyme has been conjugated with a biocompatible hydrogel polymer. Since the tumour cells release endogenous substrates of BSAO, the administration of spermine is not required. Combination with hyperthermia improves the cytocidal effect of polyamines oxidation products. Our findings show that multidrug resistant (MDR) cells are more sensitive to spermine metabolites than their wild-type counterparts, due to an increased mitochondrial activity which induces the generation of intracellular ROS prior to the onset of mitochondrial permeability transition (MPT). It makes this new approach attractive, since the development of MDR is one of the major problems of conventional cancer therapy.
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Affiliation(s)
- E Agostinelli
- Department of Biochemical Sciences A. Rossi Fanelli, Institute of Molecular Biology and Pathology, University of Rome La Sapienza and CNR, Rome, Italy.
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14
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Via LD, Marini AM, Salerno S, Toninello A. Mitochondrial permeability transition induced by novel pyridothiopyranopyrimidine derivatives: Potential new antimitochondrial antitumour agents. Biochem Pharmacol 2006; 72:1657-67. [PMID: 16982035 DOI: 10.1016/j.bcp.2006.07.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 07/28/2006] [Accepted: 07/31/2006] [Indexed: 01/12/2023]
Abstract
New pyridothiopyranopyrimidine derivatives (PTP1 and PTP2) were synthesised. Evaluation of the antiproliferative activity showed a significant capacity of the two compounds to inhibit cell growth. Investigation of the mechanism of action reveals that PTP1 interferes with the mitochondrial functions by inducing both swelling of the mitochondrial matrix and collapse of the electrical potential. These phenomena are fully prevented by typical inhibitors of the mitochondrial permeability transition, and are accompanied by the release of cytochrome c in the cytosol. The estimation of the redox state of thiol groups and glutathione suggests that the induction of permeability transition mediated by PTP1 is the result of an oxidative stress. The ability of cyclosporin A to prevent the antiproliferative effect of PTP1 indicates the induction of mitochondrial permeability transition as the molecular event responsible for the inhibition of cell growth. PTP1 also induces DNA fragmentation in intact cells. As regards PTP2, the presence of the p-toluensulphonamido group makes the lead chromophore unable to induce any effect on mitochondria.
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Affiliation(s)
- Lisa Dalla Via
- Department of Pharmaceutical Sciences, University of Padova, Via F. Marzolo, 5 I-35131 Padova, Italy
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15
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Malekova L, Kominkova V, Ferko M, Stefanik P, Krizanova O, Ziegelhöffer A, Szewczyk A, Ondrias K. Bongkrekic acid and atractyloside inhibits chloride channels from mitochondrial membranes of rat heart. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1767:31-44. [PMID: 17123460 DOI: 10.1016/j.bbabio.2006.10.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/22/2006] [Accepted: 10/09/2006] [Indexed: 01/12/2023]
Abstract
The aim of this work was to characterize the effect of bongkrekic acid (BKA), atractyloside (ATR) and carboxyatractyloside (CAT) on single channel properties of chloride channels from mitochondria. Mitochondrial membranes isolated from a rat heart muscle were incorporated into a bilayer lipid membrane (BLM) and single chloride channel currents were measured in 250/50 mM KCl cis/trans solutions. BKA (1-100 microM), ATR and CAT (5-100 microM) inhibited the chloride channels in dose-dependent manner. The inhibitory effect of the BKA, ATR and CAT was pronounced from the trans side of a BLM and it increased with time and at negative voltages (trans-cis). These compounds did not influence the single channel amplitude, but decreased open dwell time of channels. The inhibitory effect of BKA, ATR and CAT on the mitochondrial chloride channel may help to explain some of their cellular and/or subcellular effects.
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Affiliation(s)
- Lubica Malekova
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlarska 5, 833 34 Bratislava, Slovak Republic
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Tay VKS, Wang AS, Leow KY, Ong MMK, Wong KP, Boelsterli UA. Mitochondrial permeability transition as a source of superoxide anion induced by the nitroaromatic drug nimesulide in vitro. Free Radic Biol Med 2005; 39:949-59. [PMID: 16140214 DOI: 10.1016/j.freeradbiomed.2005.05.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 05/09/2005] [Accepted: 05/10/2005] [Indexed: 11/20/2022]
Abstract
Nimesulide, a widely used nonsteroidal anti-inflammatory drug containing a nitroaromatic moiety, has been associated with rare but serious hepatic adverse effects. The mechanisms underlying this idiosyncratic hepatotoxicity are unknown; however, both mitochondrial injury and oxidative stress have been implicated in contributing to liver injury in susceptible patients. The aim of this study was, first, to explore whether membrane permeability transition (MPT) could contribute to nimesulide's mitochondrial toxicity and, second, whether metabolism-derived reactive oxygen species (ROS) were responsible for MPT. We found that isolated mouse liver mitochondria readily underwent Ca2+-dependent, cyclosporin A-sensitive MPT upon exposure to nimesulide (at >or=3 microM). Net increases in mitochondrial superoxide anion levels, determined with the fluorescent probe dihydroethidium, were induced by nimesulide only in the presence of Ca2+ and were cyclosporin A-sensitive, indicating that superoxide production was a consequence, rather than the cause, of MPT. In addition, nimesulide caused a rapid dissipation of the inner mitochondrial transmembrane potential (at >or=3 microM), followed by a concentration-dependent decrease in ATP biosynthesis. Because nimesulide, unlike the related nitroaromatic drug nilutamide, did not produce any detectable ROS during incubation with mouse hepatic microsomes, we conclude that mitochondrial uncoupling causes MPT and that ROS production is a secondary effect.
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Affiliation(s)
- Vincent K S Tay
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, 18 Medical Drive, Singapore 117597
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17
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Vesce S, Jekabsons MB, Johnson-Cadwell LI, Nicholls DG. Acute glutathione depletion restricts mitochondrial ATP export in cerebellar granule neurons. J Biol Chem 2005; 280:38720-8. [PMID: 16172117 DOI: 10.1074/jbc.m506575200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Decreases in GSH pools detected during ischemia sensitize neurons to excitotoxic damage. Thermodynamic analysis predicts that partial GSH depletion will cause an oxidative shift in the thiol redox potential. To investigate the acute bioenergetic consequences, neurons were exposed to monochlorobimane (mBCl), which depletes GSH by forming a fluorescent conjugate. Neurons transfected with redox-sensitive green fluorescent protein showed a positive shift in thiol redox potential synchronous with the formation of the conjugate. Mitochondria within neurons treated with mBCl for 1 h failed to hyperpolarize upon addition of oligomycin to inhibit their ATP synthesis. A decreased ATP turnover was confirmed by monitoring neuronal oxygen consumption in parallel with mitochondrial membrane potential (Deltapsi(m)) and GSH-mBCl formation. mBCl progressively decreased cell respiration, with no effect on mitochondrial proton leak or maximal respiratory capacity, suggesting adequate glycolysis and a functional electron transport chain. This approach to "state 4" could be mimicked by the adenine nucleotide translocator inhibitor bongkrekic acid, which did not further decrease respiration when administered after mBCl. The cellular ATP/ADP ratio was decreased by mBCl, and consistent with mitochondrial ATP export failure, respiration could not respond to an increased cytoplasmic ATP demand by plasma membrane Na(+) cycling; instead, mitochondria depolarized. More prolonged mBCl exposure induced mitochondrial failure, with Deltapsi(m) collapse followed by cytoplasmic Ca(2+) deregulation. The initial bioenergetic consequence of neuronal GSH depletion in this model is thus an inhibition of ATP export, which precedes other forms of mitochondrial dysfunction.
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Affiliation(s)
- Sabino Vesce
- Buck Institute for Age Research, Novato, California 94945, USA.
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Zoratti M, Szabò I, De Marchi U. Mitochondrial permeability transitions: how many doors to the house? BIOCHIMICA ET BIOPHYSICA ACTA 2005; 1706:40-52. [PMID: 15620364 DOI: 10.1016/j.bbabio.2004.10.006] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 10/20/2004] [Accepted: 10/21/2004] [Indexed: 12/18/2022]
Abstract
The inner mitochondrial membrane is famously impermeable to solutes not provided with a specific carrier. When this impermeability is lost, either in a developmental context or under stress, the consequences for the cell can be far-reaching. Permeabilization of isolated mitochondria, studied since the early days of the field, is often discussed as if it were a biochemically well-defined phenomenon, occurring by a unique mechanism. On the contrary, evidence has been accumulating that it may be the common outcome of several distinct processes, involving different proteins or protein complexes, depending on circumstances. A clear definition of this putative variety is a prerequisite for an understanding of mitochondrial permeabilization within cells, of its roles in the life of organisms, and of the possibilities for pharmacological intervention.
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Affiliation(s)
- Mario Zoratti
- CNR Institute of Neuroscience, Biomembranes Section, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy.
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