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Vue Z, Murphy A, Le H, Neikirk K, Garza-Lopez E, Marshall AG, Mungai M, Jenkins B, Vang L, Beasley HK, Ezedimma M, Manus S, Whiteside A, Forni MF, Harris C, Crabtree A, Albritton CF, Jamison S, Demirci M, Prasad P, Oliver A, Actkins KV, Shao J, Zaganjor E, Scudese E, Rodriguez B, Koh A, Rabago I, Moore JE, Nguyen D, Aftab M, Kirk B, Li Y, Wandira N, Ahmad T, Saleem M, Kadam A, Katti P, Koh HJ, Evans C, Koo YD, Wang E, Smith Q, Tomar D, Williams CR, Sweetwyne MT, Quintana AM, Phillips MA, Hubert D, Kirabo A, Dash C, Jadiya P, Kinder A, Ajijola OA, Miller-Fleming TW, McReynolds MR, Hinton A. MICOS Complex Loss Governs Age-Associated Murine Mitochondrial Architecture and Metabolism in the Liver, While Sam50 Dictates Diet Changes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599846. [PMID: 38979162 PMCID: PMC11230271 DOI: 10.1101/2024.06.20.599846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The liver, the largest internal organ and a metabolic hub, undergoes significant declines due to aging, affecting mitochondrial function and increasing the risk of systemic liver diseases. How the mitochondrial three-dimensional (3D) structure changes in the liver across aging, and the biological mechanisms regulating such changes confers remain unclear. In this study, we employed Serial Block Face-Scanning Electron Microscopy (SBF-SEM) to achieve high-resolution 3D reconstructions of murine liver mitochondria to observe diverse phenotypes and structural alterations that occur with age, marked by a reduction in size and complexity. We also show concomitant metabolomic and lipidomic changes in aged samples. Aged human samples reflected altered disease risk. To find potential regulators of this change, we examined the Mitochondrial Contact Site and Cristae Organizing System (MICOS) complex, which plays a crucial role in maintaining mitochondrial architecture. We observe that the MICOS complex is lost during aging, but not Sam50. Sam50 is a component of the sorting and assembly machinery (SAM) complex that acts in tandem with the MICOS complex to modulate cristae morphology. In murine models subjected to a high-fat diet, there is a marked depletion of the mitochondrial protein SAM50. This reduction in Sam50 expression may heighten the susceptibility to liver disease, as our human biobank studies corroborate that Sam50 plays a genetically regulated role in the predisposition to multiple liver diseases. We further show that changes in mitochondrial calcium dysregulation and oxidative stress accompany the disruption of the MICOS complex. Together, we establish that a decrease in mitochondrial complexity and dysregulated metabolism occur with murine liver aging. While these changes are partially be regulated by age-related loss of the MICOS complex, the confluence of a murine high-fat diet can also cause loss of Sam50, which contributes to liver diseases. In summary, our study reveals potential regulators that affect age-related changes in mitochondrial structure and metabolism, which can be targeted in future therapeutic techniques.
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Affiliation(s)
- Zer Vue
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Alexandria Murphy
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801
| | - Han Le
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kit Neikirk
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Edgar Garza-Lopez
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Andrea G. Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Margaret Mungai
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Brenita Jenkins
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801
| | - Larry Vang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Heather K. Beasley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Mariaassumpta Ezedimma
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Sasha Manus
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Aaron Whiteside
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Maria Fernanda Forni
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Chanel Harris
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Biomedical Sciences, School of Graduate Studies, Meharry Medical College, Nashville, TN 37208-3501, USA
| | - Amber Crabtree
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Claude F. Albritton
- Department of Biomedical Sciences, School of Graduate Studies, Meharry Medical College, Nashville, TN 37208-3501, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sydney Jamison
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Mert Demirci
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Praveena Prasad
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801
| | - Ashton Oliver
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Ky’Era V. Actkins
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Jianqiang Shao
- Central Microscopy Research Facility, University of Iowa, Iowa City, IA, 52242, USA
| | - Elma Zaganjor
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Estevão Scudese
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Benjamin Rodriguez
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Alice Koh
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Izabella Rabago
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Johnathan E. Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Desiree Nguyen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Muhammad Aftab
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Benjamin Kirk
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Yahang Li
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Nelson Wandira
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Taseer Ahmad
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Pharmacology, College of Pharmacy, University of Sargodha, Sargodha, Punjab,40100, Pakistan
| | - Mohammad Saleem
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ashlesha Kadam
- Department of Internal Medicine, Section of Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157 USA
| | - Prasanna Katti
- National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
- Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, AP, 517619, India
| | - Ho-Jin Koh
- Department of Biological Sciences, Tennessee State University, Nashville, TN 37209, USA
| | - Chantell Evans
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27708, USA
| | - Young Do Koo
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, Iowa, USA1
| | - Eric Wang
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA, 92697, USA
| | - Quinton Smith
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA, 92697, USA
| | - Dhanendra Tomar
- Department of Pharmacology, College of Pharmacy, University of Sargodha, Sargodha, Punjab,40100, Pakistan
| | - Clintoria R. Williams
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435 USA
| | - Mariya T. Sweetwyne
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Anita M. Quintana
- Department of Biological Sciences, Border Biomedical Research Center, The University of Texas at El Paso, El Paso, Texas, USA
| | - Mark A. Phillips
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA
| | - David Hubert
- Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Immunobiology, Nashville, TN, 37232, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN, 37232, USA
- Vanderbilt Institute for Global Health, Nashville, TN, 37232, USA
| | - Chandravanu Dash
- Department of Microbiology, Immunology and Physiology, Meharry Medical College, Nashville, TN, United States
| | - Pooja Jadiya
- Department of Internal Medicine, Section of Gerontology and Geriatric Medicine, Sticht Center for Healthy Aging and Alzheimer’s Prevention, Wake Forest University School of Medicine, Winston-Salem, NC
| | - André Kinder
- Artur Sá Earp Neto University Center – UNIFASE-FMP, Petrópolis Medical School, Brazil
| | - Olujimi A. Ajijola
- UCLA Cardiac Arrhythmia Center, University of California, Los Angeles, CA, USA
| | - Tyne W. Miller-Fleming
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Melanie R. McReynolds
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
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Vilas-Boas EA, Cabral-Costa JV, Ramos VM, Caldeira da Silva CC, Kowaltowski AJ. Goldilocks calcium concentrations and the regulation of oxidative phosphorylation: Too much, too little, or just right. J Biol Chem 2023; 299:102904. [PMID: 36642177 PMCID: PMC9947387 DOI: 10.1016/j.jbc.2023.102904] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Calcium (Ca2+) is a key regulator in diverse intracellular signaling pathways and has long been implicated in metabolic control and mitochondrial function. Mitochondria can actively take up large amounts of Ca2+, thereby acting as important intracellular Ca2+ buffers and affecting cytosolic Ca2+ transients. Excessive mitochondrial matrix Ca2+ is known to be deleterious due to opening of the mitochondrial permeability transition pore (mPTP) and consequent membrane potential dissipation, leading to mitochondrial swelling, rupture, and cell death. Moderate Ca2+ within the organelle, on the other hand, can directly or indirectly activate mitochondrial matrix enzymes, possibly impacting on ATP production. Here, we aimed to determine in a quantitative manner if extra- or intramitochondrial Ca2+ modulates oxidative phosphorylation in mouse liver mitochondria and intact hepatocyte cell lines. To do so, we monitored the effects of more modest versus supraphysiological increases in cytosolic and mitochondrial Ca2+ on oxygen consumption rates. Isolated mitochondria present increased respiratory control ratios (a measure of oxidative phosphorylation efficiency) when incubated with low (2.4 ± 0.6 μM) and medium (22.0 ± 2.4 μM) Ca2+ concentrations in the presence of complex I-linked substrates pyruvate plus malate and α-ketoglutarate, respectively, but not complex II-linked succinate. In intact cells, both low and high cytosolic Ca2+ led to decreased respiratory rates, while ideal rates were present under physiological conditions. High Ca2+ decreased mitochondrial respiration in a substrate-dependent manner, mediated by mPTP. Overall, our results uncover a Goldilocks effect of Ca2+ on liver mitochondria, with specific "just right" concentrations that activate oxidative phosphorylation.
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Affiliation(s)
- Eloisa A Vilas-Boas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
| | - João Victor Cabral-Costa
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Vitor M Ramos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | | | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
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Wilson ER, Kugathasan U, Abramov AY, Clark AJ, Bennett DLH, Reilly MM, Greensmith L, Kalmar B. Hereditary sensory neuropathy type 1-associated deoxysphingolipids cause neurotoxicity, acute calcium handling abnormalities and mitochondrial dysfunction in vitro. Neurobiol Dis 2018; 117:1-14. [PMID: 29778900 PMCID: PMC6060082 DOI: 10.1016/j.nbd.2018.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/23/2018] [Accepted: 05/16/2018] [Indexed: 01/03/2023] Open
Abstract
Hereditary sensory neuropathy type 1 (HSN-1) is a peripheral neuropathy most frequently caused by mutations in the SPTLC1 or SPTLC2 genes, which code for two subunits of the enzyme serine palmitoyltransferase (SPT). SPT catalyzes the first step of de novo sphingolipid synthesis. Mutations in SPT result in a change in enzyme substrate specificity, which causes the production of atypical deoxysphinganine and deoxymethylsphinganine, rather than the normal enzyme product, sphinganine. Levels of these abnormal compounds are elevated in blood of HSN-1 patients and this is thought to cause the peripheral motor and sensory nerve damage that is characteristic of the disease, by a largely unresolved mechanism. In this study, we show that exogenous application of these deoxysphingoid bases causes dose- and time-dependent neurotoxicity in primary mammalian neurons, as determined by analysis of cell survival and neurite length. Acutely, deoxysphingoid base neurotoxicity manifests in abnormal Ca2+ handling by the endoplasmic reticulum (ER) and mitochondria as well as dysregulation of cell membrane store-operated Ca2+ channels. The changes in intracellular Ca2+ handling are accompanied by an early loss of mitochondrial membrane potential in deoxysphingoid base-treated motor and sensory neurons. Thus, these results suggest that exogenous deoxysphingoid base application causes neuronal mitochondrial dysfunction and Ca2+ handling deficits, which may play a critical role in the pathogenesis of HSN-1.
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Affiliation(s)
- Emma R Wilson
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Umaiyal Kugathasan
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Andrey Y Abramov
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Alex J Clark
- Neural Injury Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - David L H Bennett
- Neural Injury Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Linda Greensmith
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Bernadett Kalmar
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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Sims CA, Yuxia G, Singh K, Werlin EC, Reilly PM, Baur JA. Supplemental arginine vasopressin during the resuscitation of severe hemorrhagic shock preserves renal mitochondrial function. PLoS One 2017; 12:e0186339. [PMID: 29065123 PMCID: PMC5655425 DOI: 10.1371/journal.pone.0186339] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 10/01/2017] [Indexed: 01/30/2023] Open
Abstract
Arginine vasopressin (AVP), a hormone secreted by the posterior pituitary, plays a vital role in maintaining vasomotor tone during acute blood loss. We hypothesized that decompensated hemorrhagic shock is associated with decreased AVP stores and supplementation during resuscitation would improve both blood pressure and renal function. Using a decompensated hemorrhagic shock model, male Long-Evans rats were bled to mean arterial blood pressure (MAP) of 40mmHg and maintained until the MAP could not be sustained without fluid. Once 40% of the shed volume was returned in lactated Ringer’s (Severe Shock), animals were resuscitated over 60 minutes with 4x the shed volume in lactated Ringer’s (LR) or the same fluids with AVP (0.5 units/kg+ 0.03 units/kg/min). Animals (n = 6-9/group) were sacrificed before hemorrhage (Sham), at Severe Shock, following resuscitation (60R, 60R with AVP) or 18 hours post-resuscitation (18hr, 18hr with AVP). Blood samples were taken to measure AVP levels and renal function. Pituitaries were harvested and assayed for AVP. Kidney samples were taken to assess mitochondrial function, histology, and oxidative damage. Baseline pituitary AVP stores (30,364 ± 5311 pg/mg) decreased with severe shock and were significantly depressed post-resuscitation (13,910 ± 3016 pg/ml. p<0.05) and at 18hr (15,592 ±1169 pg/ml, p<0.05). Resuscitation with LR+AVP led to higher serum AVP levels at 60R (31±8 vs 79±12; p<0.01) with an improved MAP both at 60R (125±3 vs 77±7mmHg; p<0.01) and 18hr (82±6 vs 69±5mmHg;p<0.05). AVP supplementation preserved complex I respiratory capacity at 60R and both complex I and II function at 18hr (p<0.05). AVP was also associated with decreased reactive oxygen species at 60R (856±67 vs 622±48F RFU) and significantly decreased oxidative damage as measured by mitochondrial lipid peroxidation (0.9±0.1 vs 1.7±0.1 fold change, p<0.01) and nitrosylation (0.9±0.1 vs 1.4±0.2 fold change, p<0.05). With AVP, renal damage was mitigated at 60R and histologic architecture was conserved at 18 hours. In conclusion, pituitary and serum AVP levels decrease during severe hemorrhage and may contribute to the development of decompensated hemorrhagic shock. Supplementing exogenous AVP during resuscitation improves blood pressure, preserves renal mitochondrial function, and mitigates acute kidney injury.
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Affiliation(s)
- Carrie A. Sims
- The Trauma Center at the University of Pennsylvania, Department of Surgery, Perelman School of Medicine, Philadelphia, PA, United States of America
- Penn Acute Research Collaboration (PARC), University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail:
| | - Guan Yuxia
- The Trauma Center at the University of Pennsylvania, Department of Surgery, Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Khushboo Singh
- The Trauma Center at the University of Pennsylvania, Department of Surgery, Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Evan C. Werlin
- Department of Surgery, University of California, San Francisco, San Francisco, CA, United States of America
| | - Patrick M. Reilly
- The Trauma Center at the University of Pennsylvania, Department of Surgery, Perelman School of Medicine, Philadelphia, PA, United States of America
| | - Joseph A. Baur
- Penn Acute Research Collaboration (PARC), University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
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Role of time delay on intracellular calcium dynamics driven by non-Gaussian noises. Sci Rep 2016; 6:25067. [PMID: 27121687 PMCID: PMC4848611 DOI: 10.1038/srep25067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/11/2016] [Indexed: 12/26/2022] Open
Abstract
Effect of time delay (τ) on intracellular calcium dynamics with non-Gaussian noises in transmission processes of intracellular Ca2+ is studied by means of second-order stochastic Runge-Kutta type algorithm. By simulating and analyzing time series, normalized autocorrelation function, and characteristic correlation time of cytosolic and calcium store’s Ca2+ concentration, the results exhibit: (i) intracellular calcium dynamics’s time coherence disappears and stability strengthens as τ → 0.1s; (ii) for the case of τ < 0.1s, the normalized autocorrelation functions of cytosolic and calcium store’s Ca2+ concentration show damped motion when τ is very short, but they trend to a level line as τ → 0.1s, and for the case of τ > 0.1s, they show different variation as τ increases, the former changes from underdamped motion to a level line, but the latter changes from damped motion to underdamped motion; and (iii) at the moderate value of time delay, reverse resonance occurs both in cytosol and calcium store.
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Dedkova EN, Blatter LA. Calcium signaling in cardiac mitochondria. J Mol Cell Cardiol 2013; 58:125-33. [PMID: 23306007 DOI: 10.1016/j.yjmcc.2012.12.021] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/01/2012] [Accepted: 12/28/2012] [Indexed: 01/02/2023]
Abstract
Mitochondrial Ca signaling contributes to the regulation of cellular energy metabolism, and mitochondria participate in cardiac excitation-contraction coupling (ECC) through their ability to store Ca, shape the cytosolic Ca signals and generate ATP required for contraction. The mitochondrial inner membrane is equipped with an elaborate system of channels and transporters for Ca uptake and extrusion that allows for the decoding of cytosolic Ca signals, and the storage of Ca in the mitochondrial matrix compartment. Controversy, however remains whether the fast cytosolic Ca transients underlying ECC in the beating heart are transmitted rapidly into the matrix compartment or slowly integrated by the mitochondrial Ca transport machinery. This review summarizes established and novel findings on cardiac mitochondrial Ca transport and buffering, and discusses the evidence either supporting or arguing against the idea that Ca can be taken up rapidly by mitochondria during ECC.
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Affiliation(s)
- Elena N Dedkova
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612, USA
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Xu L, Gao J, Wang Y, Yu W, Zhao X, Yang X, Zhong Z, Qian ZM. Myrica rubra Extracts Protect the Liver from CCl(4)-Induced Damage. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:518302. [PMID: 20019074 PMCID: PMC3135754 DOI: 10.1093/ecam/nep196] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 10/26/2009] [Indexed: 11/14/2022]
Abstract
The relationship between the expression of mitochondrial voltage-dependent anion channels (VDACs) and the protective effects of Myrica rubra Sieb. Et Zucc fruit extract (MCE) against carbon tetrachloride (CCl(4))-induced liver damage was investigated. Pretreatment with 50 mg kg(-1), 150 mg kg(-1) or 450 mg kg(-1) MCE significantly blocked the CCl(4)-induced increase in both serum aspartate aminotransferase (sAST) and serum alanine aminotransferase (sALT) levels in mice (P < .05 or .01 versus CCl(4) group). Ultrastructural observations of decreased nuclear condensation, ameliorated mitochondrial fragmentation of the cristae and less lipid deposition by an electron microscope confirmed the hepatoprotection. The mitochondrial membrane potential dropped from -191.94 ± 8.84 mV to -132.06 ± 12.26 mV (P < .01) after the mice had been treated with CCl(4). MCE attenuated CCl(4)-induced mitochondrial membrane potential dissipation in a dose-dependent manner. At a dose of 150 or 450 mg kg(-1) of MCE, the mitochondrial membrane potentials were restored (P < .05). Pretreatment with MCE also prevented the elevation of intra-mitochondrial free calcium as observed in the liver of the CCl(4)-insulted mice (P < .01 versus CCl(4) group). In addition, MCE treatment (50-450 mg kg(-1)) significantly increased both transcription and translation of VDAC inhibited by CCl(4). The above data suggest that MCE mitigates the damage to liver mitochondria induced by CCl(4), possibly through the regulation of mitochondrial VDAC, one of the most important proteins in the mitochondrial outer membrane.
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Affiliation(s)
- Lizhi Xu
- Jiangsu Key Laboratory of Molecular Medicine, School of Medicine, Nanjing University, Nanjing, China
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Devi SL, Anuradha CV. Oxidative and nitrosative stress in experimental rat liver fibrosis: Protective effect of taurine. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2010; 29:104-110. [PMID: 21787590 DOI: 10.1016/j.etap.2009.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 09/30/2009] [Accepted: 11/18/2009] [Indexed: 05/31/2023]
Abstract
Taurine (TAU) has protective effects on experimental liver fibrosis. The present study investigates whether benefits of TAU are mediated through attenuation of oxidative and nitrosative stresses. Liver fibrosis was induced in male Wistar rats by simultaneous administration of iron (0.5%, w/w) and ethanol (6g/kg/day) for 60 days consecutively. Significant increases in thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, protein carbonyl content and loss of non-protein, protein and total thiols were observed in the liver of iron plus alcohol-fed rats. Nitrosative stress was marked by increased levels of S-nitrosothiols and decreased nitrite content. Accumulation of nitrated and oxidatively modified proteins in liver was further evidenced by immunohistochemical localization with specific antibodies for 4-hydroxynonenol (4-HNE), 3-nitrotyrosine (3-NT) and dinitrophenol (DNP). Decrease in mitochondrial ion-transport enzymes and disturbances in calcium and iron levels were also observed in these rats. TAU administration (2% (w/v) in drinking water) significantly reduced the levels of lipid hydroperoxides, TBARS, protein carbonyl with concomitant elevation in thiol levels. The presence of 4-HNE, 3-NT and DNP-protein adducts was minimal. TAU also improved mitochondrial enzyme activities and regulated iron and calcium levels. These results show that the restorative effect of taurine in fibrosis involves amelioration of protein and lipid damage by decreasing oxidative and nitrosative stresses.
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Affiliation(s)
- Shanmugam Lakshmi Devi
- Department of Biochemistry and Biotechnology, Annamalai University, Annamalai Nagar 608002, Chidambaram, Tamil Nadu, India
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Feldkamp T, Park JS, Pasupulati R, Amora D, Roeser NF, Venkatachalam MA, Weinberg JM. Regulation of the mitochondrial permeability transition in kidney proximal tubules and its alteration during hypoxia-reoxygenation. Am J Physiol Renal Physiol 2009; 297:F1632-46. [PMID: 19741014 PMCID: PMC2801335 DOI: 10.1152/ajprenal.00422.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 09/03/2009] [Indexed: 12/30/2022] Open
Abstract
Development of the mitochondrial permeability transition (MPT) can importantly contribute to lethal cell injury from both necrosis and apoptosis, but its role varies considerably with both the type of cell and type of injury, and it can be strongly opposed by the normally abundant endogenous metabolites ADP and Mg(2+). To better characterize the MPT in kidney proximal tubule cells and assess its contribution to injury to them, we have refined and validated approaches to follow the process in whole kidney proximal tubules and studied its regulation in normoxic tubules and after hypoxia-reoxygenation (H/R). Physiological levels of ADP and Mg(2+) greatly decreased sensitivity to the MPT. Inhibition of cyclophilin D by cyclosporine A (CsA) effectively opposed the MPT only in the presence of ADP and/or Mg(2+). Nonesterified fatty acids (NEFA) had a large role in the decreased resistance to the MPT seen after H/R irrespective of the available substrate or the presence of ADP, Mg(2+), or CsA, but removal of NEFA was less effective at restoring normal resistance to the MPT in the presence of electron transport complex I-dependent substrates than with succinate. The data indicate that the NEFA accumulation that occurs during both hypoxia in vitro and ischemic acute kidney injury in vivo is a critical sensitizing factor for the MPT that overcomes the antagonistic effect of endogenous metabolites and cyclophilin D inhibition, particularly in the presence of complex I-dependent substrates, which predominate in vivo.
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Affiliation(s)
- Thorsten Feldkamp
- Nephrology Division, Dept. of Internal Medicine, Univ. of Michigan Medical Center, Ann Arbor, MI 48109-0676, USA
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10
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Differential effects of non-steroidal anti-inflammatory drugs on mitochondrial dysfunction during oxidative stress. Arch Biochem Biophys 2009; 490:1-8. [DOI: 10.1016/j.abb.2009.07.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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11
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Aroclor 1254 induced cytotoxicity and mitochondrial dysfunction in isolated rat hepatocytes. Toxicology 2009; 262:175-83. [PMID: 19486918 DOI: 10.1016/j.tox.2009.05.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 05/21/2009] [Accepted: 05/22/2009] [Indexed: 01/24/2023]
Abstract
Polychlorinated biphenyls (PCBs) are widespread persistent environmental contaminants that display a complex spectrum of toxicological properties, including hepatotoxicity. Although Aroclor 1254 is ubiquitous in the environment, its potential cytotoxic effect on rat hepatocytes and the mechanism underlines its cytotoxicity are not fully investigated. Therefore, the present study was conducted to investigate: (1) the potential cytotoxicity of Aroclor 1254 in rat hepatocytes, and (2) characterization of the molecular mechanisms involved in the Aroclor 1254-induced hepatotoxicity, particularly the role of mitochondria, possibly a primary target in such event, could greatly explain the cytotoxic effect of Aroclor 1254 in rat hepatocytes. Hepatocytes were isolated from adult male albino rats and incubated for 24h in a fresh media containing 0, 20, 30, 40, 50 or 60muM of Aroclor 1254. At the end of incubation, hepatocytes and hepatocyte mitochondria were used for the assay. Our results showed cytotoxicity of Aroclor 1254 in rat hepatocytes starting at a concentration of 30muM as manifested by increased lactate dehydrogenase (LDH) leakage, decreased cell viability (MTT assay) and increased lipid peroxidation. As mitochondria are known to be one possible site of the cell damage, the effects of Aroclor 1254 on hepatocyte mitochondria was investigated. Aroclor 1254 induced reactive oxygen species (ROS) generation in hepatocyte mitochondria, inhibited mitochondrial respiratory chain complexes I and III and beta-oxidation of free fatty acids, depletion of mitochondrial antioxidant enzymes GPx and GR and the non-enzymatic antioxidant reduced glutathione, inhibited mitochondrial membrane potential (Deltapsi(m)), decreased mitochondrial aconitase and cardiolipin content, and elevated levels of cytochrome P450 subfamily, CYP1A and CYP2B activities as indicated by ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-deethylase (PROD). Therefore, we can conclude that Aroclor 1254 induced rat hepatocyte toxicity and our findings provide evidence to propose that mitochondria are one of the most important and earliest cell targets in Aroclor 1254-mediated toxicity and delineate several mitochondrial processes at least, in part, by induction of oxidative stress. These findings can be useful in future cytoprotective therapy approaches. Since mitochondrial events appear to be targeted in hepatocellular damage induced by Aroclor 1254, an antioxidant therapy targeted to mitochondria may constitute an interesting strategy to ameliorate its toxicity.
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12
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Celsi F, Pizzo P, Brini M, Leo S, Fotino C, Pinton P, Rizzuto R. Mitochondria, calcium and cell death: a deadly triad in neurodegeneration. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:335-44. [PMID: 19268425 DOI: 10.1016/j.bbabio.2009.02.021] [Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 12/17/2022]
Abstract
Mitochondrial Ca(2+) accumulation is a tightly controlled process, in turn regulating functions as diverse as aerobic metabolism and induction of cell death. The link between Ca(2+) (dys)regulation, mitochondria and cellular derangement is particularly evident in neurodegenerative disorders, in which genetic models and environmental factors allowed to identify common traits in the pathogenic routes. We will here summarize: i) the current view of mechanisms and functions of mitochondrial Ca(2+) homeostasis, ii) the basic principles of organelle Ca(2+) transport, iii) the role of Ca(2+) in neuronal cell death, and iv) the new information on the pathogenesis of Alzheimer's, Huntington's and Parkinson's diseases, highlighting the role of Ca(2+) and mitochondria.
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Affiliation(s)
- Fulvio Celsi
- Department of Experimental and Diagnostic Medicine, Interdisciplinary Center for the Study of Inflammation, Italy
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13
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Yu Y, Niapour M, Zhang Y, Berger SA. Mitochondrial regulation by c-Myc and hypoxia-inducible factor-1 alpha controls sensitivity to econazole. Mol Cancer Ther 2008; 7:483-91. [PMID: 18347136 DOI: 10.1158/1535-7163.mct-07-2050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Econazole is an azole antifungal with anticancer activity that blocks Ca(2+) influx and stimulates endoplasmic reticulum (ER) Ca(2+) release through the generation of mitochondrial reactive oxygen species (ROS), resulting in sustained depletion of ER Ca(2+) stores, protein synthesis inhibition, and cell death. c-Myc, a commonly activated oncogene, also promotes apoptosis in response to growth factor withdrawal and a variety of chemotherapeutic agents. We have investigated the role of c-myc in regulating sensitivity to econazole. Here, we show that c-myc-negative cells are profoundly resistant to econazole. c-Myc-negative rat fibroblasts failed to generate mitochondrial ROS in response to econazole and consequently failed to deplete the ER of Ca(2+). HL60 cells knocked down for c-myc expression also displayed decreased ROS generation and decreased econazole sensitivity. Addition of H(2)O(2) restored sensitivity to econazole in both c-myc-negative rat fibroblasts and c-myc knocked-down HL60 cells, supporting a role for ROS in cell death induction. c-Myc-negative cells and HL60 cells knocked down for c-myc have reduced mitochondrial content compared with c-myc-positive cells. The hypoxia sensor, hypoxia-inducible factor-1alpha (HIF-1alpha), interacts antagonistically with c-myc and also regulates mitochondrial biogenesis. Knockdown of HIF-1alpha in c-myc-negative cells increased mitochondrial content restored ROS generation in response to econazole and increased sensitivity to the drug. Taken together, these results show that c-myc and HIF-1alpha regulate sensitivity to econazole by modulating the ability of the drug to generate mitochondrial ROS.
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Affiliation(s)
- Yongmao Yu
- Arthritis and Immune Disorder Research Centre, University Health Network, Toronto Medical Discovery Tower, Toronto, ON, Canada
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14
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Koshkin V, Dai FF, Robson-Doucette CA, Chan CB, Wheeler MB. Limited Mitochondrial Permeabilization Is an Early Manifestation of Palmitate-induced Lipotoxicity in Pancreatic β-Cells. J Biol Chem 2008; 283:7936-48. [DOI: 10.1074/jbc.m705652200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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15
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Chapter Two Evaluation of Some Cell Death Features by Real Time Real Space Microscopy. Methods Enzymol 2008; 442:27-50. [DOI: 10.1016/s0076-6879(08)01402-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Wallace KB. Adriamycin-induced interference with cardiac mitochondrial calcium homeostasis. Cardiovasc Toxicol 2007; 7:101-7. [PMID: 17652813 DOI: 10.1007/s12012-007-0008-2] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/30/2022]
Abstract
Adriamycin (doxorubicin) is a potent and broad-spectrum antineoplastic agent, the clinical utility of which is limited by the development of a cumulative and irreversible cardiomyopathy. Although the drug affects numerous structures in different cell types, the mitochondrion appears to a principal subcellular target for the development of cardiomyopathy. This review describes evidence demonstrating that adriamycin redox cycles on complex I of the mitochondrial electron transport chain to liberate highly reactive free radical species of molecular oxygen. The primary effect of adriamycin on mitochondrial performance is the interference with oxidative phosphorylation and inhibition of ATP synthesis. Free radicals liberated from adriamycin redox cycling are thought to be responsible for many of the secondary effects of adriamycin, including lipid peroxidation, the oxidation of both proteins and DNA, and the depletion of glutathione and pyridine nucleotide reducing equivalents in the cell. It is this altered redox status that is believed to cause assorted changes in intracellular regulation, including the induction of the mitochondrial permeability transition and complete loss of mitochondrial integrity and function. Associated with this is the interference with mitochondrial-mediated cell calcium signaling, which is implicated as essential to the capacity of mitochondria to participate in bioenergetic regulation in response to external signals reflecting changes in metabolic demand. If taken to an extreme, this loss of mitochondrial plasticity may manifest in the liberation of signals mediating either oncotic or necrotic cell death, further perpetuating the cardiac failure associated with adriamycin-induced mitochondrial cardiomyopathy.
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Affiliation(s)
- Kendall B Wallace
- Department of Biochemistry & Molecular Biology, University of Minnesota School of Medicine, Duluth, MN 55812, USA.
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17
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Carlson DE, Nguyen PX, Soane L, Fiedler SM, Fiskum G, Chiu WC, Scalea TM. HYPOTENSIVE HEMORRHAGE INCREASES CALCIUM UPTAKE CAPACITY AND BCL-XL CONTENT OF LIVER MITOCHONDRIA. Shock 2007; 27:192-8. [PMID: 17224795 DOI: 10.1097/01.shk.0000238067.77202.a8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We tested the hypothesis that the response of mitochondrial uptake of calcium and content of Bcl proteins to reversible hemorrhagic shock increases the vulnerability for hepatocellular death. Pentobarbital-anesthetized rats were bled to a mean arterial pressure of 30 to 40 mmHg for 1 h. A subset was then resuscitated (isotonic sodium chloride solution, three times shed volume). Liver mitochondria were isolated at the end of hemorrhage and 1.5 h after the onset of resuscitation. Resuscitation accelerated mitochondrial respiration in the presence of adenosine diphosphate (state 3) above control (P<0.01). The respiratory control ratio ([RCR] state 3/state 4) was calculated using the respiratory rate in the presence of carboxyatractyloside (state 4). The RCR was depressed at the end of hemorrhage and recovered completely in response to resuscitation (P<0.05). The mitochondrial capacity for calcium uptake increased at the end of hemorrhage and remained greater than control (P<0.01) after resuscitation when plasma ornithine carbamoyltransferase (an index of hepatocellular injury) was greater than control (P<0.05). At this time, the capacity for calcium uptake was correlated with plasma ornithine carbamoyltransferase (r=0.819, P<0.01). Mitochondrial content of Bcl-xL, an antiapoptotic protein, was increased at the end of hemorrhage (P<0.03) with no further change after resuscitation and no change in mitochondrial Bak, a proapoptotic protein. Thus, mitochondrial mechanisms are triggered early during reversible hypovolemia that may limit the intensity of intracellular calcium signaling and its potential to cause cellular injury and death.
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Affiliation(s)
- Drew E Carlson
- Program in Trauma and Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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18
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Satrústegui J, Pardo B, Del Arco A. Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling. Physiol Rev 2007; 87:29-67. [PMID: 17237342 DOI: 10.1152/physrev.00005.2006] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ca2+signaling in mitochondria is important to tune mitochondrial function to a variety of extracellular stimuli. The main mechanism is Ca2+entry in mitochondria via the Ca2+uniporter followed by Ca2+activation of three dehydrogenases in the mitochondrial matrix. This results in increases in mitochondrial NADH/NAD ratios and ATP levels and increased substrate uptake by mitochondria. We review evidence gathered more than 20 years ago and recent work indicating that substrate uptake, mitochondrial NADH/NAD ratios, and ATP levels may be also activated in response to cytosolic Ca2+signals via a mechanism that does not require the entry of Ca2+in mitochondria, a mechanism depending on the activity of Ca2+-dependent mitochondrial carriers (CaMC). CaMCs fall into two groups, the aspartate-glutamate carriers (AGC) and the ATP-Mg/Picarriers, also named SCaMC (for short CaMC). The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle, and citrin, the liver AGC, is also a member of the urea cycle. Both types of CaMCs are activated by Ca2+in the intermembrane space and function together with the Ca2+uniporter in decoding the Ca2+signal into a mitochondrial response.
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Affiliation(s)
- Jorgina Satrústegui
- Departamento de Biología Molecular Centro de Biología Molecular "Severo Ochoa" UAM-CSIC, Facultad de Ciencias, Universidad Autónoma, Madrid, Spain.
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19
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Hansen ME, Pessah IN, Matsumura F. Heptachlor epoxide induces a non-capacitative type of Ca2+ entry and immediate early gene expression in mouse hepatoma cells. Toxicology 2006; 220:218-31. [PMID: 16469423 DOI: 10.1016/j.tox.2006.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 01/02/2006] [Accepted: 01/05/2006] [Indexed: 10/25/2022]
Abstract
The effects of the organochlorine (OC) liver tumor promoter heptachlor epoxide (HE) and a related non-tumor promoting OC, delta-hexachlorocyclohexane (delta-HCH), on the dynamics of intracellular calcium (Ca2+) were investigated in mouse 1c1c7 hepatoma cells. HE induced a non-capacitative, Ca2+ entry-like phenomenon, which was transient and concentration-dependent with 10 and 50 microM HE. The plasma membrane Ca2+ channel blocker SKF-96365 antagonized this HE-induced Ca2+ entry. delta-HCH failed to induce Ca2+ entry, rather it antagonized the HE-induced Ca2+ entry. Both HE and delta-HCH induced Ca2+ release from endoplasmic reticulum (ER) at treatment concentrations as low as 10 microM; at 50 microM, the former induced 5x as much Ca2+ release as the latter. The HE-induced Ca2+ release from the ER was antagonized using the IP3 receptor/channel blocker xestospongin C, suggesting that HE induces ER Ca2+ release through the IP3 receptor/channel pore. These results show that the effect of HE on cellular Ca2+ mimics that of mitogens such as epidermal and hepatocyte growth factors. They also provide insight into the similarities and differences between tumorigenic and non-tumorigenic OCs, in terms of the mechanisms and the extent of the [Ca2+]i increased by these agents.
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Affiliation(s)
- Mark E Hansen
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
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20
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Tang X, Gao J, Wang Y, Fan YM, Xu LZ, Zhao XN, Xu Q, Qian ZM. Effective protection of Terminalia catappa L. leaves from damage induced by carbon tetrachloride in liver mitochondria. J Nutr Biochem 2006; 17:177-82. [PMID: 16169207 DOI: 10.1016/j.jnutbio.2005.06.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 06/21/2005] [Accepted: 06/21/2005] [Indexed: 01/06/2023]
Abstract
The protective effects of chloroform extracts of Terminalia catappa L. leaves (TCCE) on carbon tetrachloride (CCl4)-induced liver damage and the possible mechanisms involved in the protection were investigated in mice. We found that increases in the activity of serum aspartate aminotransferase and alanine aminotransferase and the level of liver lipid peroxidation (2.0-fold, 5.7-fold and 2.8-fold) induced by CCl4 were significantly inhibited by oral pretreatment with 20, 50 or 100 mg/kg of TCCE. Morphological observation further confirmed the hepatoprotective effects of TCCE. In addition, the disruption of mitochondrial membrane potential (14.8%), intramitochondrial Ca2+ overload (2.1-fold) and suppression of mitochondrial Ca2+-ATPase activity (42.0%) in the liver of CCl4-insulted mice were effectively prevented by pretreatment with TCCE. It can be concluded that TCCE have protective activities against liver mitochondrial damage induced by CCl4, which suggests a new mechanism of the hepatoprotective effects of TCCE.
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Affiliation(s)
- Xinhui Tang
- Institute of Materia Medica, School of Medicine and State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, PR China
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21
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Theodossiou TA, Noronha-Dutra A, Hothersall JS. Mitochondria are a primary target of hypericin phototoxicity: Synergy of intracellular calcium mobilisation in cell killing. Int J Biochem Cell Biol 2006; 38:1946-56. [PMID: 16814590 DOI: 10.1016/j.biocel.2006.05.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Revised: 05/08/2006] [Accepted: 05/18/2006] [Indexed: 11/28/2022]
Abstract
Hypericin, a naturally occurring anthraquinone synthesised by hypericum, upon light activation exhibits photodynamic cytotoxicity attributed mainly to the production of reactive oxygen species. This study aimed to elucidate the primary subcellular targets and mechanistic aspects of hypericin photosensitization in human prostate carcinoma cells. Depletion of intracellular glutathione (>85%) via inhibition of gamma-glutamyl-cysteine synthase had no effect on hypericin (5 microM) phototoxicity, thus precluding any direct oxidative involvement of H2O2. There was no change in intracellular SOD activity immediately after hypericin irradiation (1.5-5 J cm(-2)). Evaluation of the lysosomal enzyme hexosaminidase activity showed: (a) 60% cell loss 22 h following irradiation (1.5 J cm(-2)) and (b) a steady rate of lysosomal leakage to the cytosol (25%), at the same time and irradiation. However, lysosomal damage appears to be a slower process compared to the rapid loss of mitochondrial function, as reflected from parallel tetrazolium to formazan assays. The activity of cytosolic and mitochondrial aconitase, an enzyme exquisitely sensitive to oxidation, revealed a dose correlated loss of activity in the mitochondria immediately following hypericin photoactivation. The use of ionomycin, which modulates both internal Ca2+ stores and external Ca2+ transport during hypericin photosensitization, profoundly enhanced photocytotoxicity. Our data supports a direct mitochondrial hypericin phototoxicity that does not involve glutathione/H2O2 homeostasis. Further a potential synergistic treatment combining mitochondrial targeting of photosensitisers and Ca2+ mobilisation was identified.
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Affiliation(s)
- Theodossis A Theodossiou
- Department of Medicine, The Rayne Institute, 5 University Street, University College London, London WC1E 6JJ, UK.
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22
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Therade-Matharan S, Laemmel E, Carpentier S, Obata Y, Levade T, Duranteau J, Vicaut E. Reactive oxygen species production by mitochondria in endothelial cells exposed to reoxygenation after hypoxia and glucose depletion is mediated by ceramide. Am J Physiol Regul Integr Comp Physiol 2005; 289:R1756-62. [PMID: 16278342 DOI: 10.1152/ajpregu.00480.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In endothelium, reoxygenation after hypoxia (H/R) has been shown to induce production of reactive oxygen species (ROS) by complex III of the mitochondrial respiratory chain. The purpose of the present study was to test the involvement of ceramide in this phenomenon. Human umbilical vein endothelial cells underwent 2 h of hypoxia (Po2, ∼20 mmHg) without glucose and 1 h of reoxygenation (Po2, ∼120 mmHg) with glucose. ROS production was measured by the fluorescent marker 2′,7′-dichlorodihydrofluorescein diacetate, and cell death by propidium iodide. We showed that 1) after 1 h of reoxygenation, fluorescence had risen and that ROS production was inhibited by desipramine, an inhibitor of sphingomyelinase, an enzyme responsible for ceramide production (126 ± 7% vs. 48 ± 12%, P < 0.05); 2) administration of ceramide ( N-acetylsphingosine) per se (i.e., in the absence of H/R) induced ROS production (65 ± 3%), which was inhibited by complex III inhibitor: antimycin A (24 ± 3%, P < 0.0001), or stigmatellin (31 ± 2%, P < 0.0001); 3) hypoxia/reoxygenation-induced ROS production was not affected by either ceramide-activated protein kinase inhibitor dimethyl aminopurine or mitochondrial permeability transition inhibitor cyclosporin A but was significantly inhibited by the antiapoptotic protein Bcl-2 (82 ± 8%, P < 0.05); 4) ceramide-induced ROS production was also inhibited by Bcl-2 (41 ± 4%, P < 0.0001). These results demonstrate that in endothelial cells submitted to hypoxia and glucose depletion followed by reoxygenation with glucose, the pathway implicated in mitochondrial complex III ROS production is ceramide dependent and is decreased by the antiapoptotic protein Bcl-2.
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Affiliation(s)
- S Therade-Matharan
- Laboratoire d'Etude de la Microcirculation, Faculté de Médecine, Université Paris 7 10, avenue de Verdun, 75010 Paris, France
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Tang XH, Gao J, Fang F, Chen J, Xu LZ, Zhao XN, Xu Q. Hepatoprotection of oleanolic acid is related to its inhibition on mitochondrial permeability transition. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2005; 33:627-37. [PMID: 16173536 DOI: 10.1142/s0192415x05003223] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The protective effects of oleanolic acid (OA) on carbon tetrachloride (CCl4)-induced liver mitochondrial damage and the possible mechanisms were investigated. Pretreatment with OA prior to the administration of CCl4 significantly suppressed the increases of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (4.2- and 19.9-fold, respectively) in a dose-dependent manner in mice. The dissipation of mitochondrial membrane potential (14.8%) and intra-mitochondrial Ca2+ overload (2.1-fold) in livers of CCl4-insulted mice were also dose-dependently prevented by pretreatment with 20, 50 or 100 mg/kg OA. In addition, the effects of OA on liver mitochondria permeability transition (MPT) induced by Ca2+ were assessed by measuring the change in mitochondrial membrane potential, release of matrix Ca2+ and mitochondrial swelling in vitro. The results showed that preincubation with 50 or 100 microg/ml OA obviously inhibited the Ca2+-induced mitochondrial swelling, mitochondrial membrane depolarization and intra-mitochondrial Ca2+ release. It could be concluded that OA has protective effects on liver mitochondria and the mechanisms underlying its protection may be related to its inhibitory action on MPT.
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Affiliation(s)
- Xin-Hui Tang
- State Key Laboratory of Pharmaceutical Biotechnology and School of Medicine, Nanjing University, Nanjing, P. R. China
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Wu J, Danielsson A, Zern MA. Toxicity of hepatotoxins: new insights into mechanisms and therapy. Expert Opin Investig Drugs 2005; 8:585-607. [PMID: 15992118 DOI: 10.1517/13543784.8.5.585] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Liver injury caused by hepatotoxins, such as carbon tetrachloride (CCl4), ethanol, and acetaminophen (APAP), is characterised by varying degrees of hepatocyte degeneration and cell death via either apoptosis or necrosis. The generation of reactive intermediate metabolites from the metabolism of hepatotoxins, and the occurrence of reactive oxygen species (ROS) during the inflammatory reaction account for a variety of pathophysiologic pathways leading to cell death, such as covalent binding, disordered cytosolic calcium homeostasis, glutathione (GSH) depletion, onset of mitochondrial permeability transition (MPT) and associated lipid peroxidation. The metabolism of hepatotoxins by cytochrome P-450 enzyme subtypes is a key step of the intoxication; therefore, enzyme inhibitors are shown to minimise the hepatotoxin-associated liver damage. Understanding the function of transcription factors, such as nuclear factor kappaB (NF-kappaB) in acute liver injury, may provide some answers as to the molecular mechanisms of toxic insults. Moreover, substantial evidence exists that MPT is involved in ROS-associated hepatocellular injury and new findings offer a novel therapeutic approach to attenuate cell damage by blocking the onset of MPT. Thus, oxidant stress and lipid peroxidation are crucial elements leading to hepatotoxin-associated liver injury. In addition to specific treatment for a given hepatotoxin, the general strategy for prevention and treatment of the damage includes reducing the production of reactive metabolites of the hepatotoxins, using anti-oxidative agents, and selectively targeting therapeutics to Kupffer cells or hepatocytes for on-going processes, which play a role in mediating a second phase of the injury.
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Affiliation(s)
- J Wu
- Division of Gastroenterology & Hepatology, Department Medicine, Jefferson Medical College, Thomas Jefferson University, 1025 Walnut Street, Room 901, Philadelphia, PA 19107-5083, USA.
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25
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Macho A, Blanco-Molina M, Spagliardi P, Appendino G, Bremner P, Heinrich M, Fiebich BL, Muñoz E. Calcium ionophoretic and apoptotic effects of ferutinin in the human Jurkat T-cell line. Biochem Pharmacol 2004; 68:875-83. [PMID: 15294450 DOI: 10.1016/j.bcp.2004.05.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 05/13/2004] [Indexed: 01/20/2023]
Abstract
We have investigated the ionophoretic and apoptotic properties of the daucane sesquiterpene ferutinin and three related compounds, ferutidin, 2-alpha-hydroxyferutidin and teferin, all isolated from various species of plants from the genus Ferula. Ferutinin induced a biphasic elevation of intracellular Ca2+ in the leukemia T-cell line, Jurkat. First, a rapid calcium peak was observed and inhibited by BAPTA-AM. This initial calcium mobilization was followed by a sustained elevation, mediated by the entry of extracellular calcium through L-type calcium channels and sensitive to inhibition by EGTA. Moreover, ferutinin-induced apoptosis in Jurkat cells, and this event was preceded, in a cyclosporine-A sensitive manner, by a loss of mitochondrial transmembrane potential (DeltaPsim) and by an increase in intracellular reactive oxygen species. Ferutinin-induced DNA fragmentation was mediated by a caspase-3-dependent pathway, and was initiated independently of any specific phase of the cell cycle. The evaluation of ferutinin analogs in calcium mobilization and apoptosis assays showed strict structure-activity relationships, with p-hydroxylation of the benzoyl moiety being requested for activity.
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Affiliation(s)
- Antonio Macho
- Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Facultad de Medicina, Avda. de Menendez Pidal s/n, E-14004 Córdoba, Spain
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Don AS, Kisker O, Dilda P, Donoghue N, Zhao X, Decollogne S, Creighton B, Flynn E, Folkman J, Hogg PJ. A peptide trivalent arsenical inhibits tumor angiogenesis by perturbing mitochondrial function in angiogenic endothelial cells. Cancer Cell 2003; 3:497-509. [PMID: 12781367 DOI: 10.1016/s1535-6108(03)00109-0] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mitochondria are the powerhouse of the cell and their disruption leads to cell death. We have used a peptide trivalent arsenical, 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO), to inactivate the adenine nucleotide translocator (ANT) that exchanges matrix ATP for cytosolic ADP across the inner mitochondrial membrane and is the key component of the mitochondrial permeability transition pore (MPTP). GSAO triggered Ca(2+)-dependent MPTP opening by crosslinking Cys(160) and Cys(257) of ANT. GSAO treatment caused a concentration-dependent increase in superoxide levels, ATP depletion, mitochondrial depolarization, and apoptosis in proliferating, but not growth-quiescent, endothelial cells. Endothelial cell proliferation drives new blood vessel formation, or angiogenesis. GSAO inhibited angiogenesis in the chick chorioallantoic membrane and in solid tumors in mice. Consequently, GSAO inhibited tumor growth in mice with no apparent toxicity at efficacious doses.
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Affiliation(s)
- Anthony S Don
- Centre for Vascular Research, University of New South Wales and Department of Haematology, Prince of Wales Hospital, Sydney, Australia
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Smaili SS, Hsu YT, Carvalho ACP, Rosenstock TR, Sharpe JC, Youle RJ. Mitochondria, calcium and pro-apoptotic proteins as mediators in cell death signaling. Braz J Med Biol Res 2003; 36:183-90. [PMID: 12563519 DOI: 10.1590/s0100-879x2003000200004] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cellular Ca2+ signals are crucial in the control of most physiological processes, cell injury and programmed cell death through the regulation of a number of Ca2+-dependent enzymes such as phospholipases, proteases, and nucleases. Mitochondria along with the endoplasmic reticulum play pivotal roles in regulating intracellular Ca2+ content. Mitochondria are endowed with multiple Ca2+ transport mechanisms by which they take up and release Ca2+ across their inner membrane. During cellular Ca2+ overload, mitochondria take up cytosolic Ca2+, which in turn induces opening of permeability transition pores and disrupts the mitochondrial membrane potential (deltapsim). The collapse of deltapsim along with the release of cytochrome c from mitochondria is followed by the activation of caspases, nuclear fragmentation and cell death. Members of the Bcl-2 family are a group of proteins that play important roles in apoptosis regulation. Members of this family appear to differentially regulate intracellular Ca2+ level. Translocation of Bax, an apoptotic signaling protein, from the cytosol to the mitochondrial membrane is another step in this apoptosis signaling pathway.
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Affiliation(s)
- S S Smaili
- Departamento de Farmacologia, Instituto de Farmacologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
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Boustany NN, Drezek R, Thakor NV. Calcium-induced alterations in mitochondrial morphology quantified in situ with optical scatter imaging. Biophys J 2002; 83:1691-700. [PMID: 12202392 PMCID: PMC1302265 DOI: 10.1016/s0006-3495(02)73937-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Optical scatter imaging (OSI), a technique we developed recently, was used to measure the ratio of wide-to-narrow angle scatter (OSIR) within endothelial cells subjected to calcium overload (1.6 mM) after permeabilization by ionomycin. Within a few minutes of calcium overload, the mitochondria, which started as elongated organelles, rounded up into spherically shaped particles. This change in morphology was accompanied by a statistically significant 14% increase in OSIR in the cells' cytoplasm. Mitochondrial rounding and OSIR increase were suppressed by cyclosporin A (25 microM), implying that the observed geometrical and scattering changes were directly attributable to the mitochondrial permeability transition. The angular scattering properties of a long mitochondrion rounding up were approximated by numerical simulations of light scatter from an ellipsoid rounding up into a sphere. The simulations predicted a relative increase in OSIR comparable to that measured experimentally for the case where the shape transition takes place with little or no volume increase. The simulations also suggested that mitochondrial refractive index changes could not account for the OSIR changes observed. Our data show that changes in OSIR correlate with mitochondrial morphology change in situ. OSI provides a new tool for subcellular imaging and complements other microscopy methods, such as fluorescence.
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Affiliation(s)
- Nada N Boustany
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205, USA.
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29
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Salvi M, Toninello A. Aroclor 1254 inhibits the mitochondrial permeability transition and release of cytochrome c: a possible mechanism for its in vivo toxicity. Toxicol Appl Pharmacol 2001; 176:92-100. [PMID: 11601885 DOI: 10.1006/taap.2001.9271] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mitochondrial permeability transition (MPT) occurs in several forms of necrotic cell death induced by various insults, including oxidative stress, ischemia/reperfusion injury Ca(2+)-ionophore toxicity, and apoptosis. In fact, the release of an apoptogenic factor such as cytochrome c is often associated with the opening of the transition pore. The present study shows that Aroclor 1254, a mixture of polychlorinated biphenyls that was banned in the U.S. in 1977 but is still present in the environment, inhibits the MPT in a dose-dependent manner in a concentration range of 1 to 25 nmol/mg protein. The compound prevents key phenomena associated with the MPT, including colloid-osmotic swelling, the collapse of membrane potential, nonspecific bidirectional traffic of solutes through the transition pore, and the oxidation of pyridine nucleotides. In contrast, Aroclor 1254 does not inhibit uptake of Ca(2+) or P(i). The effects of Aroclor 1254 are evident both in sucrose-based media and in saline and are observed when the compound is added before the opening of the pore. Aroclor 1254 prevents MPT induction provoked by a variety of agents, including phosphate, menadione, tert-butylhydroperoxide, and atractyloside. Aroclor 1254 also inhibits the specific release of cytochrome c, a correlate of MPT induction. These effects reveal a possible toxicological mechanism of action of this compound. The possibility that its effect on mitochondrial function is linked to its action as a tumor promoter is discussed.
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Affiliation(s)
- M Salvi
- Dipartimento di Chimica Biologica, Centro delle Biomembrane del CNR, Università di Padova, Via G. Colombo 3, Padua, 35121, Italy
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30
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Smaili SS, Stellato KA, Burnett P, Thomas AP, Gaspers LD. Cyclosporin A inhibits inositol 1,4,5-trisphosphate-dependent Ca2+ signals by enhancing Ca2+ uptake into the endoplasmic reticulum and mitochondria. J Biol Chem 2001; 276:23329-40. [PMID: 11323421 DOI: 10.1074/jbc.m100989200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytosolic Ca(2+) ([Ca(2+)](i)) oscillations may be generated by the inositol 1,4,5-trisphosphate receptor (IP(3)R) driven through cycles of activation/inactivation by local Ca(2+) feedback. Consequently, modulation of the local Ca(2+) gradients influences IP(3)R excitability as well as the duration and amplitude of the [Ca(2+)](i) oscillations. In the present work, we demonstrate that the immunosuppressant cyclosporin A (CSA) reduces the frequency of IP(3)-dependent [Ca(2+)](i) oscillations in intact hepatocytes, apparently by altering the local Ca(2+) gradients. Permeabilized cell experiments demonstrated that CSA lowers the apparent IP(3) sensitivity for Ca(2+) release from intracellular stores. These effects on IP(3)-dependent [Ca(2+)](i) signals could not be attributed to changes in calcineurin activity, altered ryanodine receptor function, or impaired Ca(2+) fluxes across the plasma membrane. However, CSA enhanced the removal of cytosolic Ca(2+) by sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), lowering basal and inter-spike [Ca(2+)](i). In addition, CSA stimulated a stable rise in the mitochondrial membrane potential (DeltaPsi(m)), presumably by inhibiting the mitochondrial permeability transition pore, and this was associated with increased Ca(2+) uptake and retention by the mitochondria during a rise in [Ca(2+)](i). We suggest that CSA suppresses local Ca(2+) feedback by enhancing mitochondrial and endoplasmic reticulum Ca(2+) uptake, these actions of CSA underlie the lower IP(3) sensitivity found in permeabilized cells and the impaired IP(3)-dependent [Ca(2+)](i) signals in intact cells. Thus, CSA binding proteins (cyclophilins) appear to fine tune agonist-induced [Ca(2+)](i) signals, which, in turn, may adjust the output of downstream Ca(2+)-sensitive pathways.
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Affiliation(s)
- S S Smaili
- Departamento de Farmacologia, Universidade Federal de São Paulo 04044, UNIFESP-EPM, São Paulo 04044, Brazil
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31
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Fiskum G, Kowaltowksi AJ, Andreyev AY, Kushnareva YE, Starkov AA. Apoptosis-related activities measured with isolated mitochondria and digitonin-permeabilized cells. Methods Enzymol 2001; 322:222-34. [PMID: 10914020 DOI: 10.1016/s0076-6879(00)22023-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- G Fiskum
- Department of Anesthesiology, University of Maryland, Baltimore 21201, USA
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32
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Kawasaki K, Kuge O, Yamakawa Y, Nishijima M. Purification of phosphatidylglycerophosphate synthase from Chinese hamster ovary cells. Biochem J 2001; 354:9-15. [PMID: 11171073 PMCID: PMC1221622 DOI: 10.1042/0264-6021:3540009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Phosphatidylglycerophosphate (PGP) synthase catalyses the committed step in the biosynthesis of phosphatidylglycerol and cardiolipin in mammalian cells. Recently we isolated a Chinese hamster ovary (CHO) PGS1 cDNA encoding PGP synthase. In the present study we purified this PGP synthase to near-homogeneity from the mitochondrial fraction of CHO-K1 cells; the final enzyme preparation gave a single 60 kDa protein on SDS/PAGE. Polyclonal antibodies raised against a recombinant CHO PGS1 protein cross-reacted with the purified 60 kDa protein and with CHO membrane proteins of 60 kDa and 62 kDa that increased after transfection with the PGS1 cDNA. The 60 and 62 kDa protein levels in a PGP synthase-defective mutant of CHO-K1 cells were markedly lower than those in CHO-K1 cells. These results indicated that the purified 60 kDa protein was PGP synthase encoded by the PGS1 gene. In addition we found that the purified PGP synthase had no PGP phosphatase activity, indicating that phosphatidylglycerol was produced from CDP-diacylglycerol through two steps catalysed by distinct enzymes, PGP synthase and PGP phosphatase.
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Affiliation(s)
- K Kawasaki
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Toyama, 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan
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33
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Hajnóczky G, Csordás G, Madesh M, Pacher P. The machinery of local Ca2+ signalling between sarco-endoplasmic reticulum and mitochondria. J Physiol 2000; 529 Pt 1:69-81. [PMID: 11080252 PMCID: PMC2270182 DOI: 10.1111/j.1469-7793.2000.00069.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Growing evidence suggests that propagation of cytosolic [Ca2+] ([Ca2+]c) spikes and oscillations to the mitochondria is important for the control of fundamental cellular functions. Delivery of [Ca2+]c spikes to the mitochondria may utilize activation of the mitochondrial Ca2+ uptake sites by the large local [Ca2+]c rise occurring in the vicinity of activated sarco-endoplasmic reticulum (SR/ER) Ca2+ release channels. Although direct measurement of the local [Ca2+]c sensed by the mitochondria has been difficult, recent studies shed some light onto the molecular mechanism of local Ca2+ communication between SR/ER and mitochondria. Subdomains of the SR/ER are in close contact with mitochondria and display a concentration of Ca2+ release sites, providing the conditions for an effective delivery of released Ca2+ to the mitochondrial targets. Furthermore, many functional properties of the signalling between SR/ER Ca2+ release sites and mitochondrial Ca2+ uptake sites, including transient microdomains of high [Ca2+], saturation of mitochondrial Ca2+ uptake sites by released Ca2+, connection of multiple release sites to each uptake site and quantal transmission, are analogous to the features of the coupling between neurotransmitter release sites and postsynaptic receptors in synaptic transmission. As such, Ca2+ signal transmission between SR/ER and mitochondria may utilize discrete communication sites and a closely related functional architecture to that used for synaptic signal propagation between cells.
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Affiliation(s)
- G Hajnóczky
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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34
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Abstract
Cellular Ca2+ signals are crucial in the control of most physiological processes, cell injury and programmed cell death; mitochondria play a pivotal role in the regulation of such cytosolic Ca2+ ([Ca2+]c) signals. Mitochondria are endowed with multiple Ca2+ transport mechanisms by which they take up and release Ca2+ across their inner membrane. These transport processes function to regulate local and global [Ca2+]c, thereby regulating a number of Ca2+-sensitive cellular mechanisms. The permeability transition pore (PTP) forms the major Ca2+ efflux pathway from mitochondria. In addition, Ca2+ efflux from the mitochondrial matrix occurs by the reversal of the uniporter and through the inner membrane Na+/Ca2+ exchanger. During cellular Ca2+ overload, mitochondria take up [Ca2+]c, which, in turn, induces opening of PTP, disruption of mitochondrial membrane potential (delta(psi)m) and cell death. In apoptosis signaling, collapse of delta(psi)m and cytochrome c release from mitochondria occur followed by activation of caspases, DNA fragmentation, and cell death. Translocation of Bax, an apoptotic signaling protein from the cytosol to the mitochondrial membrane, is another step during this apoptosis-signaling pathway. The role of permeability transition in the context of cell death in relation to Bcl-2 family of proteins is discussed.
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Affiliation(s)
- S S Smaili
- Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4495, USA
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35
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Makowska A, Zablocki K, Duszyński J. The role of mitochondria in the regulation of calcium influx into Jurkat cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:877-84. [PMID: 10651826 DOI: 10.1046/j.1432-1327.2000.01066.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In electrically nonexcitable cells the activity of the plasma membrane calcium channels is controlled by events occurring in mitochondria, as well as in the lumen of the endoplasmic reticulum. Thapsigargin, a specific inhibitor of endoplasmic reticulum Ca2+-ATPase, produces the release of calcium from the endoplasmic reticulum and thus, activation of store-operated calcium channels in the plasma membrane. However, thapsigargin failed to produce significant activation of the channels in Jurkat cells that had been pretreated with mitochondria-directed agents: an uncoupler (carbonyl cyanide m-chlorophenylhydrazone) and oligomycin. This is in spite of the fact that Jurkat cells pretreated with carbonyl cyanide m-chlorophenylhydrazone plus oligomycin are otherwise energetically competent, due to a high rate of glycolysis and the inhibition of mitochondrial F1Fo-ATPase by oligomycin. The pool of intracellular ATP was found not to be influenced by the pretreatments of cells with oligomycin or with oligomycin plus carbonyl cyanide m-chlorophenylhydrazone. In the control cells, we found that the ATP pool amounted to 23.2 +/- 1.9 nmoles per 107 cells (n = 4). In cells pretreated with oligomycin the level of ATP was 21.8 +/- 1.9 nmoles per 107 cells (n = 4), and in cells pretreated with both oligomycin and an uncoupler the level of ATP was 22.1 +/- 0.2 nmoles per 107 cells (n = 3). Moreover, in cells pretreated with oligomycin plus carbonyl cyanide m-chlorophenylhydrazone and suspended in a nominally calcium-free medium, thapsigargin produces transient increases in cytosolic calcium identical to those in the control cells. Thus, this pretreatment does not modify either the content of intracellular calcium stores and/or the activity of calcium ATPase in the plasma membrane. Similar results were obtained when Jurkat cells were challenged by myxothiazol, a potent inhibitor of mitochondrial cytochrome bc1 oxidoreductase. Thapsigargin, although producing calcium release from intracellular stores, was ineffective in triggering the activation of calcium channels in the plasma membrane in the case of cells pretreated with myxothiazol and oligomycin. Our results suggest that coupled mitochondria participate directly in the control of calcium channel activity in the plasma membrane of Jurkat cells. When the mitochondrial protonmotive force is collapsed, either by carbonyl cyanide m-chlorophenylhydrazone or myxothiazol, the channel remains inactive even under conditions of empty intracellular calcium stores.
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Affiliation(s)
- A Makowska
- Department of Cellular Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
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36
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Hüser J, Blatter LA, Sheu SS. Mitochondrial calcium in heart cells: beat-to-beat oscillations or slow integration of cytosolic transients? J Bioenerg Biomembr 2000; 32:27-33. [PMID: 11768759 DOI: 10.1023/a:1005556227425] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mitochondria have been implicated in intracellular Ca2+ signaling in many cell types. The inner mitochondrial membrane contains Ca2+-transporting proteins, which catalyze Ca2+ uptake and extrusion. Intramitochondrial (matrix) Ca2+, in turn, regulates the activity of Krebs cycle dehydrogenases and, ultimately, the rate of ATP synthesis. In the myocardium, controversy remains whether the fast cytosolic Ca2+ transients underlying excitation-contraction coupling in beating cells are rapidly transmitted into the matrix compartment or slowly integrated by the mitochondrial Ca2+ transporters. This mini-review critically summarizes the recent experimental work in this field.
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Affiliation(s)
- J Hüser
- Loyola University Chicago, Stritch School of Medicine, Dept of Physiology, Maywood, Illinois 60153, USA
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37
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Abstract
Mitochondria play a central role in the survival and death of neurons. The detailed bioenergetic mechanisms by which isolated mitochondria generate ATP, sequester Ca(2+), generate reactive oxygen species, and undergo Ca(2+)-dependent permeabilization of their inner membrane are currently being applied to the function of mitochondria in situ within neurons under physiological and pathophysiological conditions. Here we review the functional bioenergetics of isolated mitochondria, with emphasis on the chemiosmotic proton circuit and the application (and occasional misapplication) of these principles to intact neurons. Mitochondria play an integral role in both necrotic and apoptotic neuronal cell death, and the bioenergetic principles underlying current studies are reviewed.
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Affiliation(s)
- D G Nicholls
- Department of Pharmacology, University of Dundee, Dundee, Scotland.
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Minamikawa T, Williams DA, Bowser DN, Nagley P. Mitochondrial permeability transition and swelling can occur reversibly without inducing cell death in intact human cells. Exp Cell Res 1999; 246:26-37. [PMID: 9882512 DOI: 10.1006/excr.1998.4290] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Severe disruption of mitochondrial function is generally considered to provide a powerful trigger for apoptosis in mammalian cells. We report here that intact cells may undergo the mitochondrial permeability transition and mitochondria swell in a fully reversible manner, without inducing cell death. Cultured human osteosarcoma cells (143B TK-) stained with JC-1, MitoTracker dyes, or calcein plus Co2+ were imaged by confocal microscopy to visualize changes of mitochondrial membrane potential (DeltaPsim), morphology, and permeability transition, respectively, during treatment with a protonophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP). Cells rapidly exhibited mitochondrial permeability transition and swelling after addition of CCCP, but the swelling subsided within hours, leaving mitochondria that appeared in punctate form, not filamentous as before CCCP treatment. Cyclosporin A impeded the permeability transition and swelling, although complete inhibition was not observed. Cells survived the dissipation of DeltaPsim by CCCP for up to 6 h without developing any obvious cell damage or signs of apoptosis. With the restoration of DeltaPsim after removal of CCCP (following 6 h of CCCP treatment), permeability transition pores were closed. These results suggest that none of the following events represent a point of no return in the process of apoptotic cell death: loss of DeltaPsim, mitochondrial permeability transition, or mitochondrial swelling.
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Affiliation(s)
- T Minamikawa
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3168, Australia
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Kruman II, Nath A, Mattson MP. HIV-1 protein Tat induces apoptosis of hippocampal neurons by a mechanism involving caspase activation, calcium overload, and oxidative stress. Exp Neurol 1998; 154:276-88. [PMID: 9878167 DOI: 10.1006/exnr.1998.6958] [Citation(s) in RCA: 313] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Patients infected with HIV-1 often exhibit cognitive deficits that are related to progressive neuronal degeneration and cell death. The protein Tat, which is released from HIV-1-infected cells, was recently shown to be toxic toward cultured neurons. We now report that Tat induces apoptosis in cultured embryonic rat hippocampal neurons. Tat induced caspase activation, and the caspase inhibitor zVAD-fmk prevented Tat-induced neuronal death. Tat induced a progressive elevation of cytoplasmic-free calcium levels, which was followed by mitochondrial calcium uptake and generation of mitochondrial-reactive oxygen species (ROS). The intracellular calcium chelator BAPTA-AM and the inhibitor of mitochondrial calcium uptake ruthenium red protected neurons against Tat-induced apoptosis. zVAD-fmk suppressed Tat-induced increases of cytoplasmic calcium levels and mitochondrial ROS accumulation, indicating roles for caspases in the perturbed calcium homeostasis and oxidative stress induced by Tat. An inhibitor of nitric oxide synthase, and the peroxynitrite scavenger uric acid, protected neurons against Tat-induced apoptosis, indicating requirements for nitric oxide production and peroxynitrite formation in the cell death process. Finally, Tat caused a delayed and progressive mitochondrial membrane depolarization, and cyclosporin A prevented Tat-induced apoptosis, suggesting an important role for mitochondrial membrane permeability transition in Tat-induced apoptosis. Collectively, our data demonstrate that Tat can induce neuronal apoptosis by a mechanism involving disruption of calcium homeostasis, caspase activation, and mitochondrial calcium uptake and ROS accumulation. Agents that interupt this apoptotic cascade may prove beneficial in preventing neuronal degeneration and associated dementia in AIDS patients.
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Affiliation(s)
- I I Kruman
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky, 40536, USA
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40
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Altered Ca2+ signaling and mitochondrial deficiencies in hippocampal neurons of trisomy 16 mice: a model of Down's syndrome. J Neurosci 1998. [PMID: 9736644 DOI: 10.1523/jneurosci.18-18-07216.1998] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It has been suggested that augmented nerve cell death in neurodegenerative diseases might result from an impairment of mitochondrial function. To test this hypothesis, we investigated age-dependent changes in neuronal survival and glutamate effects on Ca2+ homeostasis and mitochondrial energy metabolism in cultured hippocampal neurons from diploid and trisomy 16 (Ts16) mice, a model of Down's syndrome. Microfluorometric techniques were used to measure survival rate, [Ca2+]i level, mitochondrial membrane potential, and NAD(P)H autofluorescence. We found that Ts16 neurons die more than twice as fast as diploid neurons under otherwise identical culture conditions. Basal [Ca2+]i levels were elevated in Ts16 neurons. Moreover, in comparison to diploid neurons, Ts16 neurons showed a prolonged recovery of [Ca2+]i and mitochondrial membrane potential after brief glutamate application. Glutamate evoked an initial NAD(P)H decrease that was found to be extended in Ts16 neurons in comparison to diploid neurons. Furthermore, for all age groups tested, glutamate failed to cause a subsequent NAD(P)H overshoot in Ts16 cultures in contrast to diploid cultures. In the presence of cyclosporin A, an inhibitor of the mitochondrial membrane permeability transition, NAD(P)H increase was observed in both diploid and Ts16 neurons. The results support the hypothesis that Ca2+ impairs mitochondrial energy metabolism and may play a role in the pathogenesis of neurodegenerative changes in neurons from Ts16 mice.
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41
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Guo Q, Christakos S, Robinson N, Mattson MP. Calbindin D28k blocks the proapoptotic actions of mutant presenilin 1: reduced oxidative stress and preserved mitochondrial function. Proc Natl Acad Sci U S A 1998; 95:3227-32. [PMID: 9501245 PMCID: PMC19724 DOI: 10.1073/pnas.95.6.3227] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/1997] [Indexed: 02/06/2023] Open
Abstract
Mutations in the presenilin 1 (PS-1) gene account for many cases of early-onset autosomal dominant inherited forms of Alzheimer's disease. Recent findings suggest that PS-1 mutations may sensitize neurons to apoptosis induced by trophic factor withdrawal and exposure to amyloid beta-peptide (Abeta). We now report that overexpression of the calcium-binding protein calbindin D28k prevents apoptosis in cultured neural cells expressing mutant PS-1 (L286V and M146V missense mutations). Elevations of the intracellular Ca2+ concentration and generation of reactive oxygen species induced by Abeta, and potentiated by mutant PS-1, were suppressed in calbindin-overexpressing cells. Impairment of mitochondrial function by Abeta (which preceded apoptosis) was exacerbated by PS-1 mutations and was largely prevented by calbindin. These findings suggest that PS-1 mutations render neurons vulnerable to apoptosis by a mechanism involving destabilization of cellular calcium homeostasis, which leads to oxidative stress and mitochondrial dysfunction.
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Affiliation(s)
- Q Guo
- Sanders-Brown Research Center on Aging and Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY 40536, USA
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42
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Fernando KC, Gregory RB, Barritt GJ. Protein kinase A regulates the disposition of Ca2+ which enters the cytoplasmic space through store-activated Ca2+ channels in rat hepatocytes by diverting inflowing Ca2+ to mitochondria. Biochem J 1998; 330 ( Pt 3):1179-87. [PMID: 9494083 PMCID: PMC1219259 DOI: 10.1042/bj3301179] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The roles of a trimeric GTP-binding regulatory protein, protein kinase A and mitochondria in the regulation of store-activated (thapsigargin-stimulated) Ca2+ inflow in freshly-isolated rat hepatocytes were investigated. Rates of Ca2+ inflow were estimated by measuring the increase in the fluorescence of intracellular fura-2 following the addition of extracellular Ca2+ (Ca2+o) to cells incubated in the absence of added Ca2+o. Guanosine 5'-[gamma-thio]-triphosphate (GTP[S]) and AlF4(-) inhibited the thapsigargin-stimulated Ca2+o-induced increase in cytoplasmic free Ca2+ concentration ([Ca2+]c) and this inhibition was prevented by the Rp diastereoisomer of adenosine 3',5'-(cyclic)phosphoro[thioate]. cAMP, forskolin and glucagon (half-maximal effect at 10 nM) mimicked inhibition of the thapsigargin-stimulated Ca2+o-induced increase in [Ca2+]c by GTP[S], but had little effect on thapsigargin-induced release of Ca2+ from intracellular stores. Azide and carbonyl cyanide p-trifluoromethoxyphenylhydrazone inhibited the thapsigargin-stimulated Ca2+o-induced increase in [Ca2+]c in the presence of increased cAMP (induced by glucagon). In contrast, Ruthenium Red markedly enhanced the thapsigargin-stimulated Ca2+o-induced increase in [Ca2+]c in both the presence and absence of increased cAMP (induced by forskolin and dibutyryl cAMP). It is concluded that, in hepatocytes, protein kinase A regulates the disposition of Ca2+, which enters the cytoplasmic space through store-activated Ca2+ channels, by directing some of this Ca2+ to the mitochondria. The idea that caution should be exercised in using observed values of Ca2+o-induced increase in [Ca2+]c as estimates of rates of agonist-stimulated Ca2+ inflow is briefly discussed.
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Affiliation(s)
- K C Fernando
- Department of Medical Biochemistry, School of Medicine, Faculty of Health Sciences, Flinders University, G.P.O. Box 2100, Adelaide, South Australia, 5001, Australia
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Bernardi P, Colonna R, Costantini P, Eriksson O, Fontaine E, Ichas F, Massari S, Nicolli A, Petronilli V, Scorrano L. The mitochondrial permeability transition. Biofactors 1998; 8:273-81. [PMID: 9914829 DOI: 10.1002/biof.5520080315] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This review summarizes recent work on the regulation of the permeability transition pore, a cyclosporin A-sensitive mitochondrial channel that may play a role in intracellular calcium homeostasis and in a variety of forms of cell death. The basic bioenergetics aspects of pore modulation are discussed, with some emphasis on the links between oxidative stress and pore dysregulation as a potential cause of mitochondrial dysfunction that may be relevant to cell injury.
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Affiliation(s)
- P Bernardi
- CNR Unit for the Study of Biomembranes, University of Padova Medical School, Italy.
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Peng TI, Jou MJ, Sheu SS, Greenamyre JT. Visualization of NMDA receptor-induced mitochondrial calcium accumulation in striatal neurons. Exp Neurol 1998; 149:1-12. [PMID: 9454610 DOI: 10.1006/exnr.1997.6599] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ca2+ influx through NMDA receptor-gated channels and the subsequent rise in intracellular Ca2+ concentration ([Ca2+]i) have been implicated in cytotoxic processes that lead to irreversible neuronal injury. While many studies have focused on cytosolic Ca2+ homeostasis, much less is known about Ca2+ fluxes in subcellular organelles, such as mitochondria. The mitochondria play an important role in Ca2+ homeostasis by sequestering cytosolic Ca2+ loads. However, mitochondrial Ca2+ overload can impair ATP synthesis, induce free radical formation, and lead to lipid peroxidation. Thus, it is also important to understand the mitochondrial Ca2+ fluxes induced by NMDA. In this study, changes in mitochondrial Ca2+ concentration ([Ca2+]m) in cultured striatal neurons were monitored with a Ca(2+)-binding fluorescent probe, rhod-2, and laser scanning confocal microscopy. The rhod-2 fluorescence signal was highly localized in mitochondrial areas of confocal images. A rapid increase of [Ca2+]m was observed when neurons were treated with 100 microM NMDA. The increased [Ca2+]m induced by NMDA could not be observed in the presence of ruthenium red, an inhibitor of the mitochondrial Ca2+ uniporter, or CCCP, a protonophore that breaks down the mitochondrial membrane potential necessary for Ca2+ uptake. The magnitude and reversibility of changes in [Ca2+]m induced by NMDA were variable. In neurons receiving multiple pulses of NMDA, [Ca2+]m did not return to baseline. The elevated [Ca2+]m may persist indefinitely and may rise further after successive NMDA exposures. These data demonstrate that Ca2+ accumulates in mitochondria in response to NMDA receptor activation. This Ca2+ accumulation may play a role in the excitotoxic mitochondrial dysfunction induced by NMDA.
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Affiliation(s)
- T I Peng
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Morgan J, Whitaker JE, Oseroff AR. GRP78 Induction by Calcium lonophore Potentiates Photodynamic Therapy Using the Mitochondrial Targeting Dye Victoria Blue BO. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb05179.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ichas F, Jouaville LS, Mazat JP. Mitochondria are excitable organelles capable of generating and conveying electrical and calcium signals. Cell 1997; 89:1145-53. [PMID: 9215636 DOI: 10.1016/s0092-8674(00)80301-3] [Citation(s) in RCA: 595] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We report Ca2(+)-induced release of Ca2+ from mitochondria (mCICR) dependent on transitory opening of the permeability transition pore (PTP) operating in a low conductance mode. The Ca2+ fluxes taking place during mCICR are a direct consequence of the mitochondrial depolarization spike (mDPS) caused by PTP opening. Both mDPS and mCICR can propagate from one mitochondrion to another in vitro, generating traveling depolarization and Ca2+ waves. Mitochondria thus appear to be excitable organelles capable of generating and conveying electrical and Ca2+ signals. In living cells, mDPS/mCICR is triggered during IP3-induced Ca2+ mobilization and results in the amplification of the Ca2+ signals primarily emitted from the endoplasmic reticulum.
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Affiliation(s)
- F Ichas
- Department of Medical Biochemistry and Molecular Biology, Integrated Biological Systems Study Group, Victor Segalen-Bordeaux 2 University, France
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Khramtsov VV, Zimmer G. Modulation of the mitochondrial permeability transition by nitric oxide. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 246:710-8. [PMID: 9219530 DOI: 10.1111/j.1432-1033.1997.00710.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The influence of nitric oxide on mitochondrial permeability transition (MPT) phenomenon was studied. NO was generated by photolysis of S-nitroso-N-acetylcysteine, AcCys(NO), with green light (lambda = 550 nm). Two distinct effects of nitric oxide on rat liver mitochondria were identified. First, NO accelerated an onset of swelling in Ca2(+)-loaded mitochondria in a cyclosporin-A-sensitive manner acting as an inducer of permeability transition. This was, apparently, a result of irreversible alteration of mitochondrial function accompanying the inhibition of respiratory chain in the presence of calcium. Formation of ESR-visible iron-sulfur dinitrosyl complexes (g = 2.041) could also contribute to the irreversible changes resulting in MPT induction. Second, NO changed significantly the response of mitochondria to Ca2+/phosphate-induced MPT, acting as a regulator of permeability transition. In this case the action of nitric oxide led to division of the mitochondria into two subpopulations: one which underwent the rapid permeability transition and another in which the MPT was inhibited. The effect of NO on Ca2+/Pi-induced MPT was transient and resulted from reversible inhibition of cytochrome oxidase followed by the changes in transmembrane potential and Ca2+ distribution. The characteristic time of duration of these NO modulated effects depended on nitric oxide as well as on oxygen concentrations. With increasing NO at fixed oxygen concentrations, this time levelled off to reach a maximum value which was inversely related to the oxygen concentration. It is concluded that under physiological condition the duration of reversible NO effects on mitochondrial function could be determined by oxygen concentration.
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Applegate TL, Karjalainen A, Bygrave FL. Rapid Ca2+ influx induced by the action of dibutylhydroquinone and glucagon in the perfused rat liver. Biochem J 1997; 323 ( Pt 2):463-7. [PMID: 9163339 PMCID: PMC1218342 DOI: 10.1042/bj3230463] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Glucagon induces a slight Ca2+ efflux when administered to the perfused rat liver. However, the hormone promotes rapid and significant Ca2+ influx after the prior administration of 2, 5-di(t-butyl)-1,4-hydroquinone (BHQ), an agent that promotes Ca2+ release from the endoplasmic reticulum (ER). The concentrations of glucagon that promote Ca2+ influx are similar to those that promote glycogenolysis and gluconeogenesis in isolated hepatocytes. The permeable analogue of cAMP, but not that of cGMP, is able to duplicate the Ca2+-mobilizing effects of glucagon. The influx of Ca2+ into liver is blocked by Ni2+. Administration of sodium azide, an inhibitor of mitochondrial electron transport, also blocks the BHQ plus glucagon-induced Ca2+ influx and this is reversed when azide administration is terminated. The actions of azide are evident within 60 s after administration or withdrawal, and also occur when either oligomycin or fructose is co-administered; this provides evidence for an effect of azide independent of cellular ATP depletion. Measurement of total calcium in mitochondria that were isolated rapidly from perfused livers after the combined administration of glucagon and BHQ confirmed that large quantities of extracellular Ca2+ had entered these organelles. These experiments provide evidence that in the perfused rat liver the artificial emptying of the ER Ca2+ pool allows glucagon to promote rapid and sustained Ca2+ influx that seems to terminate in mitochondria.
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Affiliation(s)
- T L Applegate
- Division of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, ACT 0200, Australia
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Abstract
Excitotoxic neuronal death, associated with neurodegenerative disorders and hypoxic insults, results from excessive exposure to excitatory neurotransmitters. Glutamate neurotoxicity is triggered primarily by massive Ca2+ influx arising from overstimulation of the NMDA subtype of glutamate receptors. The underlying mechanisms, however, remain elusive. We have tested the hypothesis that mitochondria are primary targets in excitotoxicity by confocal imaging of intracellular Ca2+ ([Ca2+]i) and mitochondrial membrane potential (delta psi) on cultured rat hippocampal neurons. Sustained activation of NMDA receptors (20 min) elicits reversible elevation of [Ca2+]i. Longer activation (50 min) renders elevation of [Ca2+]i irreversible (Ca2+ overload). Susceptibility to NMDA-induced Ca2+ overload is increased when the 20 min stimuli are applied to neurons pretreated with electron transport chain inhibitors, thereby implicating mitochondria in [Ca2+]i homeostasis during excitotoxic challenges. Remarkably, delta psi exhibits prominent and persistent depolarization in response to NMDA, which closely parallels the incidence of neuronal death. Blockade of the mitochondrial permeability transition pore by cyclosporin A allows complete recovery of delta psi and prevents cell death. These results suggest that early mitochondrial damage plays a key role in induction of glutamate neurotoxicity.
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Bernardi P, Petronilli V. The permeability transition pore as a mitochondrial calcium release channel: a critical appraisal. J Bioenerg Biomembr 1996; 28:131-8. [PMID: 9132411 DOI: 10.1007/bf02110643] [Citation(s) in RCA: 344] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mitochondria from a variety of sources possess an inner membrane channel, the permeability transition pore. The pore is a voltage-dependent channel, activated by matrix Ca2+ and inhibited by matrix H+, which can be blocked by cyclosporin A, presumably after binding to mitochondrial cyclophilin. The physiological function of the permeability transition pore remains unknown. Here we evaluate its potential role as a fast Ca2+ release channel involved in mitochondrial and cellular Ca2+ homeostasis. We (i) discuss the theoretical and experimental reasons why mitochondria need a fast, inducible Ca2+ release channel; (ii) analyze the striking analogies between the mitochondrial permeability transition pore and the sarcoplasmic reticulum ryanodine receptor-Ca2+ release channel; (iii) argue that the permeability transition pore can act as a selective release channel for Ca2+ despite its apparent lack of selectivity for the transported species in vitro; and (iv) discuss the importance of mitochondria in cellular Ca2+ homeostasis, and how disruption of this function could impinge upon cell viability, particularly under conditions of oxidative stress.
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Affiliation(s)
- P Bernardi
- CNR Unit for the Study of Biomembranes, Department of Biomedical Sciences, University of Padova, Italy
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