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Zhang X, Tomar N, Kandel SM, Audi SH, Cowley AW, Dash RK. Substrate- and Calcium-Dependent Differential Regulation of Mitochondrial Oxidative Phosphorylation and Energy Production in the Heart and Kidney. Cells 2021; 11:131. [PMID: 35011693 PMCID: PMC8750792 DOI: 10.3390/cells11010131] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/26/2021] [Accepted: 12/28/2021] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial dehydrogenases are differentially stimulated by Ca2+. Ca2+ has also diverse regulatory effects on mitochondrial transporters and other enzymes. However, the consequences of these regulatory effects on mitochondrial oxidative phosphorylation (OxPhos) and ATP production, and the dependencies of these consequences on respiratory substrates, have not been investigated between the kidney and heart despite the fact that kidney energy requirements are second only to those of the heart. Our objective was, therefore, to elucidate these relationships in isolated mitochondria from the kidney outer medulla (OM) and heart. ADP-induced mitochondrial respiration was measured at different CaCl2 concentrations in the presence of various respiratory substrates, including pyruvate + malate (PM), glutamate + malate (GM), alpha-ketoglutarate + malate (AM), palmitoyl-carnitine + malate (PCM), and succinate + rotenone (SUC + ROT). The results showed that, in both heart and OM mitochondria, and for most complex I substrates, Ca2+ effects are biphasic: small increases in Ca2+ concentration stimulated, while large increases inhibited mitochondrial respiration. Furthermore, significant differences in substrate- and Ca2+-dependent O2 utilization towards ATP production between heart and OM mitochondria were observed. With PM and PCM substrates, Ca2+ showed more prominent stimulatory effects in OM than in heart mitochondria, while with GM and AM substrates, Ca2+ had similar biphasic regulatory effects in both OM and heart mitochondria. In contrast, with complex II substrate SUC + ROT, only inhibitory effects on mitochondrial respiration was observed in both the heart and the OM. We conclude that the regulatory effects of Ca2+ on mitochondrial OxPhos and ATP synthesis are biphasic, substrate-dependent, and tissue-specific.
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Affiliation(s)
- Xiao Zhang
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Namrata Tomar
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Sunil M. Kandel
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Said H. Audi
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53223, USA;
| | - Allen W. Cowley
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ranjan K. Dash
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Tanwar J, Singh JB, Motiani RK. Molecular machinery regulating mitochondrial calcium levels: The nuts and bolts of mitochondrial calcium dynamics. Mitochondrion 2021; 57:9-22. [PMID: 33316420 PMCID: PMC7610953 DOI: 10.1016/j.mito.2020.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/18/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Mitochondria play vital role in regulating the cellular energetics and metabolism. Further, it is a signaling hub for cell survival and apoptotic pathways. One of the key determinants that calibrate both cellular energetics and survival functions is mitochondrial calcium (Ca2+) dynamics. Mitochondrial Ca2+ regulates three Ca2+-sensitive dehydrogenase enzymes involved in tricarboxylic acid cycle (TCA) cycle thereby directly controlling ATP synthesis. On the other hand, excessive Ca2+ concentration within the mitochondrial matrix elevates mitochondrial reactive oxygen species (mROS) levels and causes mitochondrial membrane depolarization. This leads to opening of the mitochondrial permeability transition pore (mPTP) and release of cytochrome c into cytosol eventually triggering apoptosis. Therefore, it is critical for cell to maintain mitochondrial Ca2+ concentration. Since cells can neither synthesize nor metabolize Ca2+, it is the dynamic interplay of Ca2+ handling proteins involved in mitochondrial Ca2+ influx and efflux that take the center stage. In this review we would discuss the key molecular machinery regulating mitochondrial Ca2+ concentration. We would focus on the channel complex involved in bringing Ca2+ into mitochondrial matrix i.e. Mitochondrial Ca2+ Uniporter (MCU) and its key regulators Mitochondrial Ca2+ Uptake proteins (MICU1, 2 and 3), MCU regulatory subunit b (MCUb), Essential MCU Regulator (EMRE) and Mitochondrial Ca2+ Uniporter Regulator 1 (MCUR1). Further, we would deliberate on major mitochondrial Ca2+ efflux proteins i.e. Mitochondrial Na+/Ca2+/Li+ exchanger (NCLX) and Leucine zipper EF hand-containing transmembrane1 (Letm1). Moreover, we would highlight the physiological functions of these proteins and discuss their relevance in human pathophysiology. Finally, we would highlight key outstanding questions in the field.
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Affiliation(s)
- Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi 10025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Jaya Bharti Singh
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India
| | - Rajender K Motiani
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India.
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Pajarillo E, Nyarko-Danquah I, Adinew G, Rizor A, Aschner M, Lee E. Neurotoxicity mechanisms of manganese in the central nervous system. ADVANCES IN NEUROTOXICOLOGY 2021; 5:215-238. [PMID: 34263091 DOI: 10.1016/bs.ant.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Edward Pajarillo
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Ivan Nyarko-Danquah
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Getinet Adinew
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Asha Rizor
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, United States
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Vercesi AE, Castilho RF, Kowaltowski AJ, de Oliveira HCF, de Souza-Pinto NC, Figueira TR, Busanello ENB. Mitochondrial calcium transport and the redox nature of the calcium-induced membrane permeability transition. Free Radic Biol Med 2018; 129:1-24. [PMID: 30172747 DOI: 10.1016/j.freeradbiomed.2018.08.034] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/16/2018] [Accepted: 08/28/2018] [Indexed: 12/16/2022]
Abstract
Mitochondria possess a Ca2+ transport system composed of separate Ca2+ influx and efflux pathways. Intramitochondrial Ca2+ concentrations regulate oxidative phosphorylation, required for cell function and survival, and mitochondrial redox balance, that participates in a myriad of signaling and damaging pathways. The interaction between Ca2+ accumulation and redox imbalance regulates opening and closing of a highly regulated inner membrane pore, the membrane permeability transition pore (PTP). In this review, we discuss the regulation of the PTP by mitochondrial oxidants, reactive nitrogen species, and the interactions between these species and other PTP inducers. In addition, we discuss the involvement of mitochondrial redox imbalance and PTP in metabolic conditions such as atherogenesis, diabetes, obesity and in mtDNA stability.
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Affiliation(s)
- Anibal E Vercesi
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
| | - Roger F Castilho
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Helena C F de Oliveira
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade Estadual de Campinas, SP, Brazil
| | - Nadja C de Souza-Pinto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Tiago R Figueira
- Escola de Educação Física e Esporte de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Estela N B Busanello
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
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Wang P, Fernandez-Sanz C, Wang W, Sheu SS. Why don't mice lacking the mitochondrial Ca 2+ uniporter experience an energy crisis? J Physiol 2018; 598:1307-1326. [PMID: 30218574 DOI: 10.1113/jp276636] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/28/2018] [Indexed: 01/15/2023] Open
Abstract
Current dogma holds that the heart balances energy demand and supply effectively and sustainably by sequestering enough Ca2+ into mitochondria during heartbeats to stimulate metabolic enzymes in the tricarboxylic acid (TCA) cycle and electron transport chain (ETC). This process is called excitation-contraction-bioenergetics (ECB) coupling. Recent breakthroughs in identifying the mitochondrial Ca2+ uniporter (MCU) and its associated proteins have opened up new windows for interrogating the molecular mechanisms of mitochondrial Ca2+ homeostasis regulation and its role in ECB coupling. Despite remarkable progress made in the past 7 years, it has been surprising, almost disappointing, that germline MCU deficiency in mice with certain genetic background yields viable pups, and knockout of the MCU in adult heart does not cause lethality. Moreover, MCU deficiency results in few adverse phenotypes, normal performance, and preserved bioenergetics in the heart at baseline. In this review, we briefly assess the existing literature on mitochondrial Ca2+ homeostasis regulation and then we consider possible explanations for why MCU-deficient mice are spared from energy crises under physiological conditions. We propose that MCU and/or mitochondrial Ca2+ may have limited ability to set ECB coupling, that other mitochondrial Ca2+ handling mechanisms may play a role, and that extra-mitochondrial Ca2+ may regulate ECB coupling. Since the heart needs to regenerate a significant amount of ATP to assure the perpetuation of heartbeats, multiple mechanisms are likely to work in concert to match energy supply with demand.
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Affiliation(s)
- Pei Wang
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, 98109, USA
| | - Celia Fernandez-Sanz
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Wang Wang
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, 98109, USA
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, 19107, USA
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Defective mitochondrial and lysosomal trafficking in chorea-acanthocytosis is independent of Src-kinase signaling. Mol Cell Neurosci 2018; 92:137-148. [PMID: 30081151 DOI: 10.1016/j.mcn.2018.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/27/2018] [Accepted: 08/01/2018] [Indexed: 12/31/2022] Open
Abstract
Mutations in the VPS13A gene leading to depletion of chorein protein are causative for Chorea Acanthocytosis (ChAc), a rare devastating disease, which is characterized by neurodegeneration mainly affecting the basal ganglia as well as deformation of erythrocytes. Studies on patient blood samples highlighted a dysregulation of Actin cytoskeleton caused by downregulation of the PI3K pathway and hyper-activation of Lyn-kinase, but to what extent these mechanisms are present and relevant in the affected neurons remains elusive. We studied the effects of the absence of chorein protein on the morphology and trafficking of lysosomal and mitochondrial compartments in ChAc patient-specific induced pluripotent stem cell-derived medium spiny neurons (MSNs). Numbers of both organelle types were reduced in ChAc MSNs. Mitochondrial length was shortened and their membrane potential showed significant hyperpolarization. In contrast to previous studies, showing Lyn kinase dependency of ChAc-associated pathological events in erythrocytes, pharmacological studies demonstrate that the impairment of mitochondria and lysosomes are independent of Lyn kinase activity. These data suggest that impairment in mitochondrial and lysosomal morphologies in MSNs is not mediated by a dysregulation of Lyn kinase and thus the pathological pathways in ChAc might be - at least in part - cell-type specific.
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Liu Z, Khalil RA. Evolving mechanisms of vascular smooth muscle contraction highlight key targets in vascular disease. Biochem Pharmacol 2018; 153:91-122. [PMID: 29452094 PMCID: PMC5959760 DOI: 10.1016/j.bcp.2018.02.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 02/12/2018] [Indexed: 12/11/2022]
Abstract
Vascular smooth muscle (VSM) plays an important role in the regulation of vascular function. Identifying the mechanisms of VSM contraction has been a major research goal in order to determine the causes of vascular dysfunction and exaggerated vasoconstriction in vascular disease. Major discoveries over several decades have helped to better understand the mechanisms of VSM contraction. Ca2+ has been established as a major regulator of VSM contraction, and its sources, cytosolic levels, homeostatic mechanisms and subcellular distribution have been defined. Biochemical studies have also suggested that stimulation of Gq protein-coupled membrane receptors activates phospholipase C and promotes the hydrolysis of membrane phospholipids into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 stimulates initial Ca2+ release from the sarcoplasmic reticulum, and is buttressed by Ca2+ influx through voltage-dependent, receptor-operated, transient receptor potential and store-operated channels. In order to prevent large increases in cytosolic Ca2+ concentration ([Ca2+]c), Ca2+ removal mechanisms promote Ca2+ extrusion via the plasmalemmal Ca2+ pump and Na+/Ca2+ exchanger, and Ca2+ uptake by the sarcoplasmic reticulum and mitochondria, and the coordinated activities of these Ca2+ handling mechanisms help to create subplasmalemmal Ca2+ domains. Threshold increases in [Ca2+]c form a Ca2+-calmodulin complex, which activates myosin light chain (MLC) kinase, and causes MLC phosphorylation, actin-myosin interaction, and VSM contraction. Dissociations in the relationships between [Ca2+]c, MLC phosphorylation, and force have suggested additional Ca2+ sensitization mechanisms. DAG activates protein kinase C (PKC) isoforms, which directly or indirectly via mitogen-activated protein kinase phosphorylate the actin-binding proteins calponin and caldesmon and thereby enhance the myofilaments force sensitivity to Ca2+. PKC-mediated phosphorylation of PKC-potentiated phosphatase inhibitor protein-17 (CPI-17), and RhoA-mediated activation of Rho-kinase (ROCK) inhibit MLC phosphatase and in turn increase MLC phosphorylation and VSM contraction. Abnormalities in the Ca2+ handling mechanisms and PKC and ROCK activity have been associated with vascular dysfunction in multiple vascular disorders. Modulators of [Ca2+]c, PKC and ROCK activity could be useful in mitigating the increased vasoconstriction associated with vascular disease.
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Affiliation(s)
- Zhongwei Liu
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Raouf A Khalil
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA.
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The Involvement of Mg 2+ in Regulation of Cellular and Mitochondrial Functions. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:6797460. [PMID: 28757913 PMCID: PMC5516748 DOI: 10.1155/2017/6797460] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022]
Abstract
Mg2+ is an essential mineral with pleotropic impacts on cellular physiology and functions. It acts as a cofactor of several important enzymes, as a regulator of ion channels such as voltage-dependent Ca2+ channels and K+ channels and on Ca2+-binding proteins. In general, Mg2+ is considered as the main intracellular antagonist of Ca2+, which is an essential secondary messenger initiating or regulating a great number of cellular functions. This review examines the effects of Mg2+ on mitochondrial functions with a particular focus on energy metabolism, mitochondrial Ca2+ handling, and apoptosis.
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Grancara S, Zonta F, Ohkubo S, Brunati AM, Agostinelli E, Toninello A. Pathophysiological implications of mitochondrial oxidative stress mediated by mitochondriotropic agents and polyamines: the role of tyrosine phosphorylation. Amino Acids 2015; 47:869-83. [PMID: 25792113 DOI: 10.1007/s00726-015-1964-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/11/2015] [Indexed: 12/23/2022]
Abstract
Mitochondria, once merely considered as the "powerhouse" of cells, as they generate more than 90 % of cellular ATP, are now known to play a central role in many metabolic processes, including oxidative stress and apoptosis. More than 40 known human diseases are the result of excessive production of reactive oxygen species (ROS), bioenergetic collapse and dysregulated apoptosis. Mitochondria are the main source of ROS in cells, due to the activity of the respiratory chain. In normal physiological conditions, ROS generation is limited by the anti-oxidant enzymatic systems in mitochondria. However, disregulation of the activity of these enzymes or interaction of respiratory complexes with mitochondriotropic agents may lead to a rise in ROS concentrations, resulting in oxidative stress, mitochondrial permeability transition (MPT) induction and triggering of the apoptotic pathway. ROS concentration is also increased by the activity of amine oxidases located inside and outside mitochondria, with oxidation of biogenic amines and polyamines. However, it should also be recalled that, depending on its concentration, the polyamine spermine can also protect against stress caused by ROS scavenging. In higher organisms, cell signaling pathways are the main regulators in energy production, since they act at the level of mitochondrial oxidative phosphorylation and participate in the induction of the MPT. Thus, respiratory complexes, ATP synthase and transition pore components are the targets of tyrosine kinases and phosphatases. Increased ROS may also regulate the tyrosine phosphorylation of target proteins by activating Src kinases or phosphatases, preventing or inducing a number of pathological states.
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Affiliation(s)
- Silvia Grancara
- Department of Biomedical Sciences, University of Padova, Viale U. Bassi 58B, 35131, Padua, Italy
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Mironova GD, Saris NEL, Belosludtseva NV, Agafonov AV, Elantsev AB, Belosludtsev KN. Involvement of palmitate/Ca2+(Sr2+)-induced pore in the cycling of ions across the mitochondrial membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:488-95. [PMID: 25450352 DOI: 10.1016/j.bbamem.2014.10.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 09/23/2014] [Accepted: 10/20/2014] [Indexed: 10/24/2022]
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Abstract
Mitochondria may function as multiple separate organelles or as a single electrically coupled continuum to modulate changes in [Ca2+]c (cytoplasmic Ca2+ concentration) in various cell types. Mitochondria may also be tethered to the internal Ca2+ store or plasma membrane in particular parts of cells to facilitate the organelles modulation of local and global [Ca2+]c increases. Differences in the organization and positioning contributes significantly to the at times apparently contradictory reports on the way mitochondria modulate [Ca2+]c signals. In the present paper, we review the organization of mitochondria and the organelles role in Ca2+ signalling.
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Zampese E, Pizzo P. Intracellular organelles in the saga of Ca2+ homeostasis: different molecules for different purposes? Cell Mol Life Sci 2012; 69:1077-104. [PMID: 21968921 PMCID: PMC11114864 DOI: 10.1007/s00018-011-0845-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 11/28/2022]
Abstract
An increase in the concentration of cytosolic free Ca(2+) is a key component regulating different cellular processes ranging from egg fertilization, active secretion and movement, to cell differentiation and death. The multitude of phenomena modulated by Ca(2+), however, do not simply rely on increases/decreases in its concentration, but also on specific timing, shape and sub-cellular localization of its signals that, combined together, provide a huge versatility in Ca(2+) signaling. Intracellular organelles and their Ca(2+) handling machineries exert key roles in this complex and precise mechanism, and this review will try to depict a map of Ca(2+) routes inside cells, highlighting the uniqueness of the different Ca(2+) toolkit components and the complexity of the interactions between them.
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Affiliation(s)
- Enrico Zampese
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
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After half a century mitochondrial calcium in- and efflux machineries reveal themselves. EMBO J 2011; 30:4119-25. [PMID: 21934651 DOI: 10.1038/emboj.2011.337] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 08/26/2011] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial Ca(2+) uptake and release play a fundamental role in the control of different physiological processes, such as cytoplasmic Ca(2+) signalling, ATP production and hormone metabolism, while dysregulation of mitochondrial Ca(2+) handling triggers the cascade of events that lead to cell death. The basic mechanisms of mitochondrial Ca(2+) homeostasis have been firmly established for decades, but the molecular identities of the channels and transporters responsible for Ca(2+) uptake and release have remained mysterious until very recently. Here, we briefly review the main findings that have led to our present understanding of mitochondrial Ca(2+) homeostasis and its integration in cell physiology. We will then discuss the recent work that has unravelled the biochemical identity of three key molecules: NCLX, the mitochondrial Na(+)/Ca(2+) antiporter, MCU, the pore-forming subunit of the mitochondrial Ca(2+) uptake channel, and MICU1, one of its regulatory subunits.
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Gunter TE, Gerstner B, Lester T, Wojtovich AP, Malecki J, Swarts SG, Brookes PS, Gavin CE, Gunter KK. An analysis of the effects of Mn2+ on oxidative phosphorylation in liver, brain, and heart mitochondria using state 3 oxidation rate assays. Toxicol Appl Pharmacol 2010; 249:65-75. [PMID: 20800605 DOI: 10.1016/j.taap.2010.08.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 08/18/2010] [Accepted: 08/19/2010] [Indexed: 11/25/2022]
Abstract
Manganese (Mn) toxicity is partially mediated by reduced ATP production. We have used oxidation rate assays--a measure of ATP production--under rapid phosphorylation conditions to explore sites of Mn(2+) inhibition of ATP production in isolated liver, brain, and heart mitochondria. This approach has several advantages. First, the target tissue for Mn toxicity in the basal ganglia is energetically active and should be studied under rapid phosphorylation conditions. Second, Mn may inhibit metabolic steps which do not affect ATP production rate. This approach allows identification of inhibitions that decrease this rate. Third, mitochondria from different tissues contain different amounts of the components of the metabolic pathways potentially resulting in different patterns of ATP inhibition. Our results indicate that Mn(2+) inhibits ATP production with very different patterns in liver, brain, and heart mitochondria. The primary Mn(2+) inhibition site in liver and heart mitochondria, but not in brain mitochondria, is the F₁F₀ ATP synthase. In mitochondria fueled by either succinate or glutamate+malate, ATP production is much more strongly inhibited in brain than in liver or heart mitochondria; moreover, Mn(2+) inhibits two independent sites in brain mitochondria. The primary site of Mn-induced inhibition of ATP production in brain mitochondria when succinate is substrate is either fumarase or complex II, while the likely site of the primary inhibition when glutamate plus malate are the substrates is either the glutamate/aspartate exchanger or aspartate aminotransferase.
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Affiliation(s)
- Thomas E Gunter
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
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Contreras L, Drago I, Zampese E, Pozzan T. Mitochondria: the calcium connection. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:607-18. [PMID: 20470749 DOI: 10.1016/j.bbabio.2010.05.005] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 05/04/2010] [Accepted: 05/04/2010] [Indexed: 12/21/2022]
Abstract
Calcium handling by mitochondria is a key feature in cell life. It is involved in energy production for cell activity, in buffering and shaping cytosolic calcium rises and also in determining cell fate by triggering or preventing apoptosis. Both mitochondria and the mechanisms involved in the control of calcium homeostasis have been extensively studied, but they still provide researchers with long-standing or even new challenges. Technical improvements in the tools employed for the investigation of calcium dynamics have been-and are still-opening new perspectives in this field, and more prominently for mitochondria. In this review we present a state-of-the-art toolkit for calcium measurements, with major emphasis on the advantages of genetically encoded indicators. These indicators can be efficiently and selectively targeted to specific cellular sub-compartments, allowing previously unavailable high-definition calcium dynamic studies. We also summarize the main features of cellular and, in more detail, mitochondrial calcium handling, especially focusing on the latest breakthroughs in the field, such as the recent direct characterization of the calcium microdomains that occur on the mitochondrial surface upon cellular stimulation. Additionally, we provide a major example of the key role played by calcium in patho-physiology by briefly describing the extensively reported-albeit highly controversial-alterations of calcium homeostasis in Alzheimer's disease, casting lights on the possible alterations in mitochondrial calcium handling in this pathology.
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Affiliation(s)
- Laura Contreras
- Department of Biomedical Sciences, University of Padua, Italy.
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Gunter TE, Sheu SS. Characteristics and possible functions of mitochondrial Ca(2+) transport mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1291-308. [PMID: 19161975 PMCID: PMC2730425 DOI: 10.1016/j.bbabio.2008.12.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 12/22/2008] [Accepted: 12/29/2008] [Indexed: 02/07/2023]
Abstract
Mitochondria produce around 92% of the ATP used in the typical animal cell by oxidative phosphorylation using energy from their electrochemical proton gradient. Intramitochondrial free Ca(2+) concentration ([Ca(2+)](m)) has been found to be an important component of control of the rate of this ATP production. In addition, [Ca(2+)](m) also controls the opening of a large pore in the inner mitochondrial membrane, the permeability transition pore (PTP), which plays a role in mitochondrial control of programmed cell death or apoptosis. Therefore, [Ca(2+)](m) can control whether the cell has sufficient ATP to fulfill its functions and survive or is condemned to death. Ca(2+) is also one of the most important second messengers within the cytosol, signaling changes in cellular response through Ca(2+) pulses or transients. Mitochondria can also sequester Ca(2+) from these transients so as to modify the shape of Ca(2+) signaling transients or control their location within the cell. All of this is controlled by the action of four or five mitochondrial Ca(2+) transport mechanisms and the PTP. The characteristics of these mechanisms of Ca(2+) transport and a discussion of how they might function are described in this paper.
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Affiliation(s)
- Thomas E Gunter
- Department of Biochemistry and Biophysics and Mitochondrial Research and Innovation Group, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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19
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Liu T, O’Rourke B. Regulation of mitochondrial Ca2+ and its effects on energetics and redox balance in normal and failing heart. J Bioenerg Biomembr 2009; 41:127-32. [PMID: 19390955 PMCID: PMC2946065 DOI: 10.1007/s10863-009-9216-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ca(2+) has been well accepted as a signal that coordinates changes in cytosolic workload with mitochondrial energy metabolism in cardiomyocytes. During increased work, Ca(2+) is accumulated in mitochondria and stimulates ATP production to match energy supply and demand. The kinetics of mitochondrial Ca(2+) ([Ca(2+)](m)) uptake remains unclear, and we review the debate on this subject in this article. [Ca(2+)](m) has multiple targets in oxidative phosphorylation including the F1/FO ATPase, the adenine nucleotide translocase, and Ca(2+)-sensitive dehydrogenases (CaDH) of the tricarboxylic acid (TCA) cycle. The well established effect of [Ca(2+)](m) is to activate CaDHs of the TCA cycle to increase NADH production. Maintaining NADH level is not only critical to keep a high oxidative phosphorylation rate during increased cardiac work, but is also necessary for the reducing system of the cell to maintain its reactive oxygen species (ROS) -scavenging capacity. Further, we review recent data demonstrating the deleterious effects of elevated Na(+) in cardiac pathology by blunting [Ca(2+)](m) accumulation.
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Affiliation(s)
- Ting Liu
- Institute of Molecular Cardiobiology, Division of Cardiology, The Johns Hopkins University, Baltimore, MD, USA
| | - Brian O’Rourke
- Institute of Molecular Cardiobiology, The Johns Hopkins University, 720 Rutland Ave., 1060 Ross Bldg., Baltimore, MD 21205-2195, USA,
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20
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Castaldo P, Cataldi M, Magi S, Lariccia V, Arcangeli S, Amoroso S. Role of the mitochondrial sodium/calcium exchanger in neuronal physiology and in the pathogenesis of neurological diseases. Prog Neurobiol 2008; 87:58-79. [PMID: 18952141 DOI: 10.1016/j.pneurobio.2008.09.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 11/26/2022]
Abstract
In neurons, as in other excitable cells, mitochondria extrude Ca(2+) ions from their matrix in exchange with cytosolic Na(+) ions. This exchange is mediated by a specific transporter located in the inner mitochondrial membrane, the mitochondrial Na(+)/Ca(2+) exchanger (NCX(mito)). The stoichiometry of NCX(mito)-operated Na(+)/Ca(2+) exchange has been the subject of a long controversy, but evidence of an electrogenic 3 Na(+)/1 Ca(2+) exchange is increasing. Although the molecular identity of NCX(mito) is still undetermined, data obtained in our laboratory suggest that besides the long-sought and as yet unfound mitochondrial-specific NCX, the three isoforms of plasmamembrane NCX can contribute to NCX(mito) in neurons and astrocytes. NCX(mito) has a role in controlling neuronal Ca(2+) homeostasis and neuronal bioenergetics. Indeed, by cycling the Ca(2+) ions captured by mitochondria back to the cytosol, NCX(mito) determines a shoulder in neuronal [Ca(2+)](c) responses to neurotransmitters and depolarizing stimuli which may then outlast stimulus duration. This persistent NCX(mito)-dependent Ca(2+) release has a role in post-tetanic potentiation, a form of short-term synaptic plasticity. By controlling [Ca(2+)](m) NCX(mito) regulates the activity of the Ca(2+)-sensitive enzymes pyruvate-, alpha-ketoglutarate- and isocitrate-dehydrogenases and affects the activity of the respiratory chain. Convincing experimental evidence suggests that supraphysiological activation of NCX(mito) contributes to neuronal cell death in the ischemic brain and, in epileptic neurons coping with seizure-induced ion overload, reduces the ability to reestablish normal ionic homeostasis. These data suggest that NCX(mito) could represent an important target for the development of new neurological drugs.
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Affiliation(s)
- P Castaldo
- Department of Neuroscience, Section of Pharmacology, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Torrette di Ancona, Ancona, Italy
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21
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Abstract
The kinetic properties for the uptake, storage and release of Ca2+ from isolated mitochondria accurately predict the behaviour of the organelles within the intact cell. While the steady-state cycling of Ca2+ across the inner membrane between independent uptake and efflux pathways seems at first sight to be symmetrical, the distinctive kinetics of the uniporter, which is highly dependent on external free Ca2+ concentration and the efflux pathway, whose activity is clamped over a wide range of total matrix Ca2+ by the solubility of the calcium phosphate complex provide a mechanism whereby mitochondria reversibly sequester transient elevations in cytoplasmic Ca2+. Under non-stimulated conditions, the same transport processes can regulate matrix Ca2+ concentrations and hence citric acid cycle activity.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Age Research, Redwood Boulevard, Novato, CA 94945, USA.
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22
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Geiger JE, Magoski NS. Ca2+-induced Ca2+ release in Aplysia bag cell neurons requires interaction between mitochondrial and endoplasmic reticulum stores. J Neurophysiol 2008; 100:24-37. [PMID: 18463180 DOI: 10.1152/jn.90356.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intracellular Ca2+ is influenced by both Ca2+ influx and release. We examined intracellular Ca2+ following action potential firing in the bag cell neurons of Aplysia californica. Following brief synaptic input, these neuroendocrine cells undergo an afterdischarge, resulting in elevated Ca2+ and the secretion of neuropeptides to initiate reproduction. Cultured bag cell neurons were injected with the Ca2+ indicator, fura-PE3, and subjected to simultaneous imaging and electrophysiology. Delivery of a 5-Hz, 1-min train of action potentials (mimicking the fast phase of the afterdischarge) produced a Ca2+ rise that markedly outlasted the initial influx, consistent with Ca2+-induced Ca2+ release (CICR). This response was attenuated by about half with ryanodine or depletion of the endoplasmic reticulum (ER) by cyclopiazonic acid. However, depletion of the mitochondria, with carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone, essentially eliminated CICR. Dual depletion of the ER and mitochondria did not reduce CICR further than depletion of the mitochondria alone. Moreover, tetraphenylphosphonium, a blocker of mitochondrial Ca2+ release, largely prevented CICR. The Ca2+ elevation during and subsequent to a stimulus mimicking the full afterdischarge was prominent and enhanced by protein kinase C activation. Traditionally, the ER is seen as the primary Ca2+ source for CICR. However, bag cell neuron CICR represents a departure from this view in that it relies on store interaction, where Ca2+ released from the mitochondria may in turn liberate Ca2+ from the ER. This unique form of CICR may be used by both bag cell neurons, and other neurons, to initiate secretion, activate channels, or induce gene expression.
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Affiliation(s)
- Julia E Geiger
- Department of Physiology, Queen's University, Kingston, Ontario, Canada
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23
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Zorov DB, Isaev NK, Plotnikov EY, Zorova LD, Stelmashook EV, Vasileva AK, Arkhangelskaya AA, Khrjapenkova TG. The mitochondrion as janus bifrons. BIOCHEMISTRY (MOSCOW) 2008; 72:1115-26. [PMID: 18021069 DOI: 10.1134/s0006297907100094] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The signaling function of mitochondria is considered with a special emphasis on their role in the regulation of redox status of the cell, possibly determining a number of pathologies including cancer and aging. The review summarizes the transport role of mitochondria in energy supply to all cellular compartments (mitochondria as an electric cable in the cell), the role of mitochondria in plastic metabolism of the cell including synthesis of heme, steroids, iron-sulfur clusters, and reactive oxygen and nitrogen species. Mitochondria also play an important role in the Ca(2+)-signaling and the regulation of apoptotic cell death. Knowledge of mechanisms responsible for apoptotic cell death is important for the strategy for prevention of unwanted degradation of postmitotic cells such as cardiomyocytes and neurons.
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Affiliation(s)
- D B Zorov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia.
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24
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Gunter TE, Gavin CE, Aschner M, Gunter KK. Speciation of manganese in cells and mitochondria: a search for the proximal cause of manganese neurotoxicity. Neurotoxicology 2006; 27:765-76. [PMID: 16765446 DOI: 10.1016/j.neuro.2006.05.002] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 04/26/2006] [Accepted: 05/01/2006] [Indexed: 11/29/2022]
Abstract
Recent studies of speciation of manganese (Mn) in brain mitochondria, neuron-like cells, and astrocytes are reviewed. No evidence is found for oxidation of Mn(2+) complexes to a Mn(3+) complex. The only evidence for any Mn(3+) complex is found in a spectrum essentially identical to that of mitochondrial manganese superoxide dismutase (MnSOD). While this does not prove that no Mn(3+) is produced in these tissues by oxidation of Mn(2+), it does suggest that formation of an active Mn(3+) complex by oxidation of Mn(2+) probably does not play as important a role in Mn toxicity as has been suggested earlier. Since these results suggest that we should look elsewhere for the proximal causes of Mn neurotoxicity, we consider the possibilities that Mn(3+) may be transported into the cell via transferrin and that Mn(2+) may inhibit Ca(2+)-activation and control of the rate of ATP production by oxidative phosphorylation.
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Affiliation(s)
- Thomas E Gunter
- Department of Biophysics and Biochemistry, University of Rochester School of Medicine and Dentistry, 575 Elmwood Avenue, Rochester, NY 14642, USA.
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25
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Abstract
It has previously been reported that moderately high dietary manganese (Mn) in combination with marginal magnesium (Mg) resulted in ultrastructural damage to heart mitochondria. Manganese may replace Mg in biological functions, including the role of enzyme cofactor. Manganese may accumulate and substitute for Mg during the condition of Mg-deficiency. The objective of the current study was to determine whether high Mn alters heart muscle respiration and Mg-enzyme activity as well as whole body Mn retention under marginal Mg. An additional objective was to determine whether high Mn results in increased oxidative stress. In experiment 1: forty-eight rats were fed a 2 x 3 factorial arrangement of Mn (10, 100, or 1000 mg/kg) and Mg (200 or 500 mg/kg). In experiment 2: thirty-two rats were fed one of four diets in a 2 x 2 factorial arrangement of Mn (10 or 250 mg/kg) and Mg (200 or 500 mg/kg). In experiment 3: thirty-two rats were fed one of four diets in a 2 x 2 factorial arrangement of Mn (10 or 650 mg/kg) and Mg (200 or 500 mg/kg). In experiment 2, high Mn and marginal Mg reduced (P<0.05) oxygen consumption of left ventricle muscle. Marginal Mg, but not Mn, reduced (P<0.05) activity of sarcoplasmic reticulum calcium-ATPase enzyme. Dietary Mg had no affect on (54)Mn kinetics, but high dietary Mn decreased (P<0.01) absorption, retention, and rate of excretion of (54)Mn. Neither cellular stress, measured by Comet assay, nor antioxidant activities were increased by high Mn. A strong interaction (P<0.001) between increasing Mn and adequate Mg on hematology was observed. These results confirm previous research in swine that high Mn alters myocardial integrity as well as function, but not as a result of altered calcium transport or oxidative stress.
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Affiliation(s)
- Kevin B Miller
- Department of Animal and Range Science, North Dakota State University, Fargo, ND 58105, USA
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26
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Determining the oxidation states of manganese in NT2 cells and cultured astrocytes. Neurobiol Aging 2005; 27:1816-26. [PMID: 16290323 DOI: 10.1016/j.neurobiolaging.2005.10.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 10/11/2005] [Accepted: 10/11/2005] [Indexed: 11/18/2022]
Abstract
Excessive brain manganese (Mn) can produce a syndrome called "manganism", which correlates with loss of striatal dopamine and cell death in the striatum and globus pallidus. The prevalent hypothesis for the cause of this syndrome has been oxidation of cell components by the strong oxidizing agent, Mn(3+), either formed by oxidation of intracellular Mn(2+) or transported into the cell as Mn(3+). We have recently used X-ray absorption near edge structure spectroscopy (XANES) to determine the oxidation states of manganese complexes in brain and liver mitochondria and in nerve growth factor (NGF)-induced and non-induced PC12 cells. No evidence was found for stabilization or accumulation of Mn(3+) complexes because of oxidation of Mn(2+) by reactive oxygen species in these tissues. Here we extend these studies of manganese oxidation state to cells of brain origin, human neuroteratocarcinoma (NT2) cells and primary cultures of rat astrocytes. Again we find no evidence for stabilization or accumulation of any Mn(3+) complex derived from oxidation of Mn(2+) under a range of conditions.
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27
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Gunter KK, Aschner M, Miller LM, Eliseev R, Salter J, Anderson K, Hammond S, Gunter TE. Determining the oxidation states of manganese in PC12 and nerve growth factor-induced PC12 cells. Free Radic Biol Med 2005; 39:164-81. [PMID: 15964508 DOI: 10.1016/j.freeradbiomed.2005.03.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Revised: 01/19/2005] [Accepted: 03/02/2005] [Indexed: 11/17/2022]
Abstract
Excessive brain Mn can produce toxicity with symptoms resembling parkinsonism. This syndrome, called "manganism," correlates with loss of dopamine in the striatum and cell death in the striatum and globus pallidus. A common hypothesis is that cell damage in Mn toxicity is caused by oxidation of important cell components by Mn3+. Determination of the amount of Mn3+ present, under a range of conditions, in neuronal cells and brain mitochondria represents an important step in evaluating the "damage through oxidation by Mn3+ hypothesis." In an earlier paper we used X-ray absorption near-edge structure (XANES) spectroscopy to determine the amount of Mn2+ and Mn3+ in brain mitochondria under a range of conditions. Here we extend the study to investigate the evidence for formation of Mn3+ through oxidation of Mn2+ by ROS in PC12 cells and in PC12 cells induced with nerve growth factor (NGF) to display a phenotype more like that of neurons. Although the results suggest that very small amounts of Mn3+ might be present at low Mn levels, probably in Mn superoxide dismutase, Mn3+ is not stabilized by complex formation in these cells and therefore does not accumulate to detectable amounts.
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Affiliation(s)
- Karlene K Gunter
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 575 Elmwood Avenue, Rochester, NY 14642, USA
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28
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Salvi M, Toninello A. Effects of polyamines on mitochondrial Ca2+ transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1661:113-24. [PMID: 15003874 DOI: 10.1016/j.bbamem.2003.12.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Revised: 11/27/2003] [Accepted: 12/04/2003] [Indexed: 11/26/2022]
Abstract
Mammalian mitochondria are able to enhance Ca(2+) accumulation in the presence of polyamines by activating the saturable systems of Ca(2+) inward transport and buffering extramitochondrial Ca(2+) concentrations to levels similar to those in the cytosol of resting cells. This effect renders them responsive to regulate free Ca(2+) concentrations in the physioloical range. The mechanism involved is due to a rise in the affinity of the Ca(2+) transport system, induced by polyamines, most probably exhibiting allosteric behaviour. The regulatory site of this mechanism is the so-called S(1) binding site of polyamines, which operates in physiological conditions and is located in the energy well between the two peaks present in the energy profile of mitochondrial spermine transport. Spermine is bidirectionally transported across teh inner membrane by cycling, in which influx and efflux are driven by electrical and pH gradients, respectively. Most probably, polyamine affects the Ca(2+) transport system when it acts from the outside-that is, in the direction of its uniporter channel, in order to reach the S(1) site. Important physiological functions are related to activation of Ca(2+) transport systems by polyamines and their interactions with the S(1) site. These functions include a rise in the metabolic rate for energy supply and modulation of mitochondrial permeability transition induction, with consequent effects on the triggering of the apoptotic pathway.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Universita' di Padova, Istituto di Neuroscienze del C.N.R., Unita' per lo Studio delle Biomembrane, Via G. Colombo 3, 35121 Padua, Italy
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29
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Anderson CD, Belous A, Pierce J, Nicoud IB, Knox C, Wakata A, Pinson CW, Chari RS. Mitochondrial calcium uptake regulates cold preservation-induced Bax translocation and early reperfusion apoptosis. Am J Transplant 2004; 4:352-62. [PMID: 14961987 DOI: 10.1111/j.1600-6143.2004.00357.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mitochondrial calcium (mCa + 2) overload occurs during cold preservation and is an integral part of mitochondrial-dependent apoptotic pathways. We investigated the role of mCa + 2 overload in cell death following hypothermic storage using HepG2 cells stored in normoxic-hypothermic (4 degrees C) or hypoxic (< 0.1% O2)-hypothermic Belzer storage solution. Cells were stored for 6 h, with or without 10 microM ruthenium red (mCa + 2 uniporter inhibitor) followed by rewarming in oxygenated media at 37 degrees C. Cytoplasmic cytochrome c levels were studied by Western analysis and by fluorescent microscopy after transfection of cytochrome c-GFP expression plasmid. Immunofluorescence determined the intracellular, spatio-temporal distribution of Bax, and TUNEL staining was used to evaluate cell death after 180 min of rewarming. Caspase activation was evaluated using Western analysis and a caspase 3 activity assay. Bax translocation, cytochrome c release, and early rewarming cell death occurred following hypothermic storage and were exacerbated by hypoxia. Caspase 3 activation did not occur following hypothermic storage. Blockade of mCa + 2 uptake prevented Bax translocation, cytochrome c release, and early rewarming cell death. These studies demonstrate that mCa + 2 uptake during hypothermic storage, both hypoxic and normoxic, contributes to early rewarming apoptosis by triggering Bax translocation to mitochondria and cytochrome c release.
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Affiliation(s)
- Christopher D Anderson
- Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
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30
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Gunter TE, Miller LM, Gavin CE, Eliseev R, Salter J, Buntinas L, Alexandrov A, Hammond S, Gunter KK. Determination of the oxidation states of manganese in brain, liver, and heart mitochondria. J Neurochem 2004; 88:266-80. [PMID: 14690515 DOI: 10.1046/j.1471-4159.2003.02122.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Excess brain manganese can produce toxicity with symptoms that resemble those of Parkinsonism and causes that remain elusive. Manganese accumulates in mitochondria, a major source of superoxide, which can oxidize Mn2+ to the powerful oxidizing agent Mn3+. Oxidation of important cell components by Mn3+ has been suggested as a cause of the toxic effects of manganese. Determining the oxidation states of intramitochondrial manganese could help to identify the dominant mechanism of manganese toxicity. Using X-ray absorbance near edge structure (XANES) spectroscopy, we have characterized the oxidation state of manganese in mitochondria isolated from brain, liver, and heart over concentrations ranging from physiological to pathological. Results showed that (i) spectra from different model manganese complexes of the same oxidation state were similar to each other and different from those of other oxidation states and that the position of the absorption edge increases with oxidation state; (ii) spectra from intramitochondrial manganese in isolated brain, heart and liver mitochondria were virtually identical; and (iii) under these conditions intramitochondrial manganese exists primarily as a combination of Mn2+ complexes. No evidence for Mn3+ was detected in samples containing more than endogenous manganese levels, even after incubation under conditions promoting reactive oxygen species (ROS) production. While the presence of Mn3+ complexes cannot be proven in the spectrum of endogenous mitochondrial manganese, the shape of this spectrum could suggest the presence of Mn3+ near the limit of detection, probably as MnSOD.
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Affiliation(s)
- Thomas E Gunter
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, Rochester, New York 14642, USA.
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31
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Nieminen AL. Apoptosis and necrosis in health and disease: role of mitochondria. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 224:29-55. [PMID: 12722948 DOI: 10.1016/s0074-7696(05)24002-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mitochondria play an important role in both the life and death of cells. Mitochondria are the powerhouse of the cell, providing over 90% of adenosine triphosphate (ATP) consumed by the cell. Mitochondrial energy production, however, is disrupted in various pathological situations leading to cellular Injury. The mechanisms causing the injury are turning out to be more complex than originally expected. For instance, calcium, oxidant chemicals, ischemia/ reperfusion, and a range of other agents promote onset of the mitochondrial permeability transition in mitochondria from liver, heart, and other tissues. Often the consequence of this event is ATP depletion, ion deregulation, mitochondrial and cellular swelling, activation of degradative enzymes, plasma membrane failure, and cell lysis. This is referred to as necrotic cell death. The mitochondrial permeability transition is also involved in apoptotic cell death. In this mode of death, the role of the permeability transition is to release proapoptotic proteins from mitochondria into the cytosol where with the aid of cellular ATP they complete the apoptotic cascade. Therefore, mitochondria contribute to both apoptotic and necrotic death.
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Affiliation(s)
- Anna-Liisa Nieminen
- Department of Anatomy, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
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32
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Chavez-Crooker P, Garrido N, Ahearn GA. Copper transport by lobster (Homarus americanus) hepatopancreatic mitochondria. J Exp Biol 2002; 205:405-13. [PMID: 11854377 DOI: 10.1242/jeb.205.3.405] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Mechanisms of copper transport into purified mitochondrial suspensions prepared from the hepatopancreas of the Atlantic lobster Homarus americanus were investigated. Mitochondria were purified by combining methods of differential and Percoll-gradient centrifugation, and copper transport was studied using the copper-sensitive fluorescent dye Phen Green. Copper transport by this mitochondrial preparation was kinetically the sum of saturable and non-saturable transfer components. Addition of 500 μmol l–1 Ca2+ or 500 nmol l–1 Ruthenium Red abolished the non-saturable copper transport component, significantly (P<0.01) reduced the apparent binding affinity of the saturable transport component, but was without effect (P>0.05) on the apparent maximal transport velocity of the saturable transfer process. The antiport inhibitor diltiazem (500 μmol l–1) acted as a mixed inhibitor of the saturable transport mechanism, but had no effect on the non-saturable component of transfer. These results suggest that the non-saturable copper influx process was probably by way of the well-known Ruthenium-Red-sensitive Ca2+ uniporter and that the saturable transport component was probably due to a combination of both the Na+-dependent, diltiazem-sensitive 1Ca2+/2Na+ antiporter and the Na+-independent, diltiazem-insensitive 1Ca2+/2H+ antiporter. A model is discussed relating these mitochondrial copper uptake processes to the transfer of metal ions across the epithelial brush-border membrane.
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Affiliation(s)
- Pamela Chavez-Crooker
- Department of Zoology, 2538 The Mall, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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33
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Salvi M, Toninello A. The effect of methylglyoxal-bis(guanylhydrazone) on mitochondrial Ca(2+) fluxes. Biochem Pharmacol 2002; 63:247-50. [PMID: 11841799 DOI: 10.1016/s0006-2952(01)00827-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Methylglyoxal-bis(guanylhydrazone) (MGBG) induces a dose-dependent inhibition of the electrophoretic Ca(2+) uptake by rat liver mitochondria (RLM) without affecting the electrical membrane potential. MGBG is also able to inhibit the electroneutral Ca(2+) release from mitochondria. These effects result in a progressive increase of Ca(2+) level in suspending medium indicating that Ca(2+) uptake is inhibited at higher extent than Ca(2+) efflux. Spermine instead, induces a lowering of external Ca(2+) concentration. This action is reversed by MGBG which again raises the external Ca(2+) concentration then in the absence of spermine, though at a lower extent. The mechanism of MGBG effects and their implications on energy metabolism are discussed.
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Affiliation(s)
- Mauro Salvi
- Dipartimento di Chimica Biologica, Universita' di Padova, Centro di Studio delle Biomembrane del CNR, Viale G. Colombo 3, I-35121, Padova, Italy
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34
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Gunter TE, Buntinas L, Sparagna G, Eliseev R, Gunter K. Mitochondrial calcium transport: mechanisms and functions. Cell Calcium 2000; 28:285-96. [PMID: 11115368 DOI: 10.1054/ceca.2000.0168] [Citation(s) in RCA: 279] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ca(2+)transport across the mitochondrial inner membrane is facilitated by transporters having four distinct sets of characteristics as well as through the Ca(2+)-induced mitochondrial permeability transition pore (PTP). There are two modes of inward transport, referred to as the Ca(2+)uniporter and the rapid mode or RaM. There are also two distinct mechanisms mediating outward transport, which are not associated with the PTP, referred to as the Na(+)-dependent and the Na(+)-independent Ca(2+)efflux mechanisms. Several important functions have been proposed for these mechanisms, including control of the metabolic rate for cellular energy (ATP) production, modulation of the amplitude and shape of cytosolic Ca(2+)transients, and induction of apoptosis through release of cytochrome c from the mitochondrial inter membrane space into the cytosolic space. The goals of this review are to survey the literature describing the characteristics of the mechanisms of mitochondrial Ca(2+)transport and their proposed physiological functions, emphasizing the more recent contributions, and to consider how the observed characteristics of the mitochondrial Ca(2+)transport mechanisms affect our understanding of their functions.
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Affiliation(s)
- T E Gunter
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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35
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Abstract
This review provides a selective history of how studies of mitochondrial cation transport (K+, Na+, Ca2+) developed in relation to the major themes of research in bioenergetics. It then covers in some detail specific transport pathways for these cations, and it introduces and discusses open problems about their nature and physiological function, particularly in relation to volume regulation and Ca2+ homeostasis. The review should provide the basic elements needed to understand both earlier mitochondrial literature and current problems associated with mitochondrial transport of cations and hopefully will foster new interest in the molecular definition of mitochondrial cation channels and exchangers as well as their roles in cell physiology.
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Affiliation(s)
- P Bernardi
- Department of Biomedical Sciences, University of Padova, and Consiglio Nazionale delle Ricerche Center for the Study of Biomembranes, Padova, Italy.
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36
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Byrne AM, Lemasters JJ, Nieminen AL. Contribution of increased mitochondrial free Ca2+ to the mitochondrial permeability transition induced by tert-butylhydroperoxide in rat hepatocytes. Hepatology 1999; 29:1523-31. [PMID: 10216138 DOI: 10.1002/hep.510290521] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Previously, we showed that the oxidant chemical, tert-butylhydroperoxide (t-BuOOH), induces a mitochondrial permeability transition (MPT) in intact hepatocytes, causing lethal cell injury. Here, we investigated the role of mitochondrial free Ca2+ in t-BuOOH cytotoxicity to 1-day-cultured rat hepatocytes using confocal microscopy of autofluorescence and parameter-indicating fluorophores. t-BuOOH (100 micromol/L) caused an early increase of mitochondrial free Ca2+, as assessed by confocal microscopy of Rhod-2 fluorescence. Increased mitochondrial Ca2+ was followed by onset of the MPT, as evidenced by permeation of cytosolic calcein into mitochondria and loss of the mitochondrial membrane potential-indicating dye, tetramethylrhodamine methylester. Preincubation with an intracellular Ca2+ chelator (BAPTA-AM and its derivatives) partially blocked the late phase of mitochondrial NAD(P)H oxidation after t-BuOOH, but failed to prevent the early oxidation of mitochondrial NAD(P)H. Ca2+ chelation also prevented the increase of mitochondrial Ca2+, generation of mitochondrial reactive oxygen species (ROS), onset of the MPT, and subsequent cell death. Confocal images showed that protection occurred when loading of the Ca2+ chelator was predominantly mitochondrial. The antioxidant, desferal, also diminished increased mitochondrial Ca2+ after t-BuOOH and prevented cell death. We conclude that oxidative stress induced by t-BuOOH enhances mitochondrial Ca2+ uptake, leading to increased matrix Ca2+, increased ROS formation, onset of the MPT, and cell death.
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Affiliation(s)
- A M Byrne
- Department of Anatomy, Case Western Reserve University, Cleveland, OH 44106-4930, USA
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37
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Budd SL. Mechanisms of neuronal damage in brain hypoxia/ischemia: focus on the role of mitochondrial calcium accumulation. Pharmacol Ther 1998; 80:203-29. [PMID: 9839772 DOI: 10.1016/s0163-7258(98)00029-1] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Following a hypoxic-ischemic insult, the collapse of ion gradients results in the inappropriate release of excitatory neurotransmitters. Although excitatory amino acids such as glutamate are the likely extracellular mediators of the ensuing neuronal cell death, the intracellular events occurring downstream of glutamate receptor activation are much less clear. The present review attempts to summarize how Ca2+ overload of neurons following a hypoxic-ischemic insult is neurotoxic. In particular, the interlocked relation between mitochondrial Ca2+ accumulation and subsequent neuronal cell death is examined.
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Affiliation(s)
- S L Budd
- Neurosciences Institute, Ninewells Medical School, University of Dundee, Scotland, UK
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38
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Bowser DN, Minamikawa T, Nagley P, Williams DA. Role of mitochondria in calcium regulation of spontaneously contracting cardiac muscle cells. Biophys J 1998; 75:2004-14. [PMID: 9746542 PMCID: PMC1299872 DOI: 10.1016/s0006-3495(98)77642-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mitochondrial involvement in the regulation of cytosolic calcium concentration ([Ca2+]i) in cardiac myocytes has been largely discounted by many authors. However, recent evidence, including the results of this study, has forced a reappraisal of this role. [Ca2+]i and Ca2+ in the mitochondria ([Ca2+]m) were measured in this study with specific fluorescent probes, fluo-3 and di-hydro-rhod-2, respectively; mitochondrial membrane potential (DeltaPsim) was monitored with JC-1. Addition of uncouplers or inhibitors of the mitochondrial respiratory chain was found to cause a twofold decrease in the rate of removal of Ca2+ from the cytosol after a spontaneously generated Ca2+ wave. These agents also caused a progressive elevation of [Ca2+]i, an increase in the number of hotspots of Ca2+ release (Ca2+ sparks), and depression of mitochondrial potential. The Ca2+-indicative fluorophore dihydro-rhod-2 has a net positive charge that contributes to selective accumulation by mitochondria, as supported by its co-localization with other mitochondrial-specific probes (MitoTracker Green). Treatment of dihydro-rhod-2-loaded cells with NaCN resulted in rapid formation of "black holes" in the otherwise uniformly banded pattern. These are likely to represent individual or small groups of mitochondria that have depressed mitochondrial potential, or have lost accumulated rhod-2 and/or Ca2+; all of these eventualities are possible upon onset of the mitochondrial permeability transition. Release of Ca2+ from the sarcoplasmic reticulum and the resultant spontaneous contractility of cardiac muscle are proposed to be triggered by the induction of the mitochondrial permeability transition and the subsequent loss of [Ca2+]m.
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Affiliation(s)
- D N Bowser
- Confocal and Fluorescence Imaging Group, Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia.
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39
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Gunter TE, Buntinas L, Sparagna GC, Gunter KK. The Ca2+ transport mechanisms of mitochondria and Ca2+ uptake from physiological-type Ca2+ transients. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1366:5-15. [PMID: 9714709 DOI: 10.1016/s0005-2728(98)00117-0] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mitochondria contain a sophisticated system for transporting Ca2+. The existence of a uniporter and of both Na+-dependent and -independent efflux mechanisms has been known for years. Recently, a new mechanism, called the RaM, which seems adapted for sequestering Ca2+ from physiological transients or pulses has been discovered. The RaM shows a conductivity at the beginning of a Ca2+ pulse that is much higher than the conductivity of the uniporter. This conductivity decreases very rapidly following the increase in [Ca2+] outside the mitochondria. This decrease in the Ca2+ conductivity of the RaM is associated with binding of Ca2+ to an external regulatory site. When liver mitochondria are exposed to a sequence of pulses, uptake of labeled Ca2+ via the RaM appears additive between pulses. Ruthenium red inhibits the RaM in liver mitochondria but much larger amounts are required than for inhibition of the mitochondrial Ca2+ uniporter. Spermine, ATP and GTP increase Ca2+ uptake via the RaM. Maximum uptake via the RaM from a single Ca2+ pulse in the physiological range has been observed to be approximately 7 nmole/mg protein, suggesting that Ca2+ uptake via the RaM and uniporter from physiological pulses may be sufficient to activate the Ca2+-sensitive metabolic reactions in the mitochondrial matrix which increase the rate of ATP production. RaM-mediated Ca2+ uptake has also been observed in heart mitochondria. Evidence for Ca2+ uptake into the mitochondria in a variety of tissues described in the literature is reviewed for evidence of participation of the RaM in this uptake. Possible ways in which the differences in transport via the RaM and the uniporter may be used to differentiate between metabolic and apoptotic signaling are discussed.
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Affiliation(s)
- T E Gunter
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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40
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Saris NE. On the mechanism of rebounding of calcium in liver mitochondria. Biol Chem 1997; 378:1163-6. [PMID: 9372185 DOI: 10.1515/bchm.1997.378.10.1163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Rat liver mitochondria are able to temporarily lower the steady state concentration of external Ca2+ after having accumulated a pulse of added Ca2+. This could be due to inhibition of efflux or/and stimulation of influx of Ca2+. This question has been addressed in mitochondria respiring on succinate +/- malonate. In the presence of malonate the depression of the membrane potential during Ca2+ uptake is more extensive and the rate of Ca2+ uptake slower. There were no discernible differences in the rates of efflux either after inhibition of the calcium uniporter by Ruthenium Red or by studying efflux of preloaded 45Ca-labeled Ca2+. The efflux was not changed by diltiazem or cyclosporin A to inhibit Ca2+ exchange on the Ca2+/nNA+ antiporter or efflux through the permeability transition pore. It is concluded that the rebounding is due mainly to stimulation of the calcium uniporter.
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Affiliation(s)
- N E Saris
- Department of Medical Chemistry, University of Helsinki, Finland
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41
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Novgorodov SA, Gudz TI. Permeability transition pore of the inner mitochondrial membrane can operate in two open states with different selectivities. J Bioenerg Biomembr 1996; 28:139-46. [PMID: 9132412 DOI: 10.1007/bf02110644] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Prooxidants induce release of Ca2+ from mitochondria through the giant solute pore in the mitochondrial inner membrane. However, under appropriate conditions prooxidants can induce Ca2+ release without inducing a nonspecific permeability change. Prooxidant-induced release of Ca2+ is selective. Presumably, this is the result of the operation of a permeability pathway for H+ coupled to the reversal of the Ca2+ uniporter, the latter generating the selectivity. The solute pore and prooxidant-induced Ca2+-specific pathways exhibit common sensitivities to a set of inhibitors and activators. It is proposed that the pore can operate in two open states: (1) permeable to H+ only and (2) permeable to solutes of M(r) < 1500. Under some conditions, prooxidants induce the H+-selective state which, in turn, collapses the inner membrane potential and permits selective loss of Ca2+ via the Ca2+ uniporter.
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Affiliation(s)
- S A Novgorodov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia
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42
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Broekemeier KM, Krebsbach RJ, Pfeiffer DR. Inhibition of the mitochondrial Ca2+ uniporter by pure and impure ruthenium red. Mol Cell Biochem 1994; 139:33-40. [PMID: 7531818 DOI: 10.1007/bf00944201] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Commercial ruthenium red is often purified by a single recrystallization as described by Luft, J.H. (1971) Anat Rec 171, 347-368, which yields small amounts of material having an apparent molar extinction coefficient of approximately 67,400 at 533 nm. A simple modification to the procedure dramatically improves the yield, allowing crystallization to be repeated. Three times recrystallized ruthenium red has an apparent extinction coefficient of approximately 85,900, the highest value reported to date. Both crude and highly purified ruthenium red can be shown to inhibit reverse activity of the mitochondrial Ca2+ uniporter (uncoupled mitochondria), provided that care is taken to minimize and account for Ca2+ release through the permeability transition pore. Crude ruthenium red is 7-10 fold more potent than the highly purified material in this regard, on an actual ruthenium red concentration basis. The same relative potency is seen against forward uniport (coupled mitochondria), however, the I50 values are 10 fold lower for both the crude and purified preparations. These data demonstrate unambiguously that the energy state of mitochondria affects the sensitivity of the Ca2+ uniporter to ruthenium red preparations, and that both the forward and reverse reactions are subject to complete inhibition. The data suggest, however, that the active inhibitor may not be ruthenium red per se, but one or more of the other ruthenium complexes which are present in ruthenium red preparations.
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Affiliation(s)
- K M Broekemeier
- Ohio State University, Department of Medical Biochemistry, Columbus 43210-1218
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43
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Abstract
The identification of intramitochondrial free calcium ([Ca2+]m) as a primary metabolic mediator [see Hansford (this volume) and Gunter, T. E., Gunter, K. K., Sheu, S.-S., and Gavin, C. E. (1994) Am. J. Physiol. 267, C313-C339, for reviews] has emphasized the importance of understanding the characteristics of those mechanisms that control [Ca2+]m. In this review, we attempt to update the descriptions of the mechanisms that mediate the transport of Ca2+ across the mitochondrial inner membrane, emphasizing the energetics of each mechanism. New concepts within this field are reviewed and some older concepts are discussed more completely than in earlier reviews. The mathematical forms of the membrane potential dependence and concentration dependence of the uniporter are interpolated in such a way as to display the convenience of considering Vmax to be an explicit function of the membrane potential. Recent evidence for a transient rapid conductance state of the uniporter is discussed. New evidence concerning the energetics and stoichiometries of both Na(+)-dependent and Na(+)-independent efflux mechanisms is reviewed. Explicit mathematical expressions are used to describe the energetics of the system and the kinetics of transport via each Ca2+ transport mechanism.
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Affiliation(s)
- K K Gunter
- Department of Biophysics, University of Rochester Medical School, New York 14642
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44
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Cox D, Matlib M. A role for the mitochondrial Na(+)-Ca2+ exchanger in the regulation of oxidative phosphorylation in isolated heart mitochondria. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)54024-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Li W, Shariat-Madar Z, Powers M, Sun X, Lane R, Garlid K. Reconstitution, identification, purification, and immunological characterization of the 110-kDa Na+/Ca2+ antiporter from beef heart mitochondria. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)37140-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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46
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Hutson SM, Williams GD, Berkich DA, LaNoue KF, Briggs RW. A 31P NMR study of mitochondrial inorganic phosphate visibility: effects of Ca2+, Mn2+, and the pH gradient. Biochemistry 1992; 31:1322-30. [PMID: 1736991 DOI: 10.1021/bi00120a007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of external pH, temperature, and Ca2+ and Mn2+ concentrations on the compartmentation and NMR visibility of inorganic phosphate (Pi) were studied in isolated rat liver mitochondria respiring on succinate and glutamate. Mitochondrial matrix Pi is totally visible by NMR at 8 degrees C and at low external concentrations of Pi. However, when the external Pi concentration is increased above 7 mM, the pH gradient decreases, the amount of matrix Pi increases, and the fraction not observed by NMR increases. Raising the temperature to 25 degrees C also decreases the pH gradient and the Pi fraction observed by NMR. At physiologically relevant concentrations, Ca2+ and Mn2+ do not seem to play a major role in matrix Pi NMR invisibility. For Ca2+ concentrations above 30 nmol/mg of protein, formation of insoluble complexes will cause loss of Pi signal intensity. For Mn2+ concentrations above 2 nmol/mg of protein, the Pi peak can be broadened sufficiently to preclude detection of a high-resolution signal. The results indicate that mitochondrial matrix Pi should be mostly observable up to 25 degrees C by high-resolution NMR. While the exact nature of the NMR-invisible phosphate in perfused or in vivo liver is yet to be determined, better success at detecting and resolving both Pi pools by NMR is indicated at high field, low temperature, and optimized pulsing conditions.
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Affiliation(s)
- S M Hutson
- Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, Pennsylvania State University 17033
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47
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Zazueta C, Holguín JA, Ramírez J. Calcium transport sensitive to ruthenium red in cytochrome oxidase vesicles reconstituted with mitochondrial proteins. J Bioenerg Biomembr 1991; 23:889-902. [PMID: 1723412 DOI: 10.1007/bf00786007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We describe a calcium transport that is sensitive to ruthenium red in liposomes reconstituted with mitochondrial extracts. This system is able to build an internally negative membrane potential, which allows the electrogenic influx of Ca2+ and Sr2+. Proteins with molecular weights higher than 35 kDa were incorporated to the vesicles, and enhanced the accumulation of the cation in an energy-dependent fashion.
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Affiliation(s)
- C Zazueta
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, México, D.F
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48
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Gunter K, Zuscik M, Gunter T. The Na(+)-independent Ca2+ efflux mechanism of liver mitochondria is not a passive Ca2+/2H+ exchanger. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54685-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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49
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Igbavboa U, Pfeiffer DR. Transient induction of the mitochondrial permeability transition by uncoupler plus a Ca(2+)-specific chelator. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1059:339-47. [PMID: 1716985 DOI: 10.1016/s0005-2728(05)80219-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Determinations of aqueous space volumes, swelling and Mg2+ release experiments demonstrate that EGTA plus uncoupler causes the permeability transition in Ca(2+)-loaded mitochondria. Extramitochondrial Mg2+ is required to obtain this effect. Changes in transition-dependent parameters are smaller and more varied when induced by EGTA plus uncoupler than when induced by Ruthenium red plus uncoupler, although inhibitor-sensitive experiments show that the same basic mechanism is involved in both cases. Measurements of sucrose trapping and sucrose or inulin accessible space, after changes in transition-dependent parameters are complete, indicate that rapid reversal occurs when the transition is induced by EGTA plus uncoupler, explaining why limited responses are obtained. Data support the hypothesis that an external divalent cation binding site regulates activity of the mitochondrial Ca2+ uniporter.
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Affiliation(s)
- U Igbavboa
- Hormel Institute, University of Minnesota, Austin 55912
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50
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Gavin CE, Gunter KK, Gunter TE. Manganese and calcium efflux kinetics in brain mitochondria. Relevance to manganese toxicity. Biochem J 1990; 266:329-34. [PMID: 2317189 PMCID: PMC1131135 DOI: 10.1042/bj2660329] [Citation(s) in RCA: 200] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Manganese shares the uniport mechanism of mitochondrial calcium influx, accumulates in mitochondria and is cleared only very slowly from brain. Using dual-label isotope techniques, we have investigated both Mn2+ and Ca2+ mitochondrial efflux kinetics. We report that (1) there is no significant Na(+)-dependent Mn2+ efflux from brain mitochondria; (2) Mn2+ inhibits both Na(+)-dependent and Na(+)-independent Ca2+ efflux in brain, in a mode that appears to be primarily competitive and with apparent Ki values of 5.1 and 7.9 nmol/mg respectively; and (3) Ca2+ does not appear to inhibit Mn2+ efflux from brain mitochondria. Findings (1) and (2) suggest the possibility of mitochondrial accumulation of both Mn2+ and Ca2+ in Mn2(+)-intoxicated brain.
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Affiliation(s)
- C E Gavin
- University of Rochester Medical Center, NY 14642
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