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Carafoli E. The interplay of mitochondria with calcium: an historical appraisal. Cell Calcium 2012; 52:1-8. [PMID: 22591641 DOI: 10.1016/j.ceca.2012.02.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 11/26/2022]
Abstract
Indirect findings in the 1950s had indicated that mitochondria could accumulate Ca(2+), but only in 1961 isolated mitochondria were directly shown to take it up in a process driven by the activity of the respiratory chain or by the hydrolysis of added ATP. The uptake of Ca(2+) could be accompanied by the simultaneous uptake of inorganic phosphate, leading to the precipitation of hydroxyapatite in the matrix and to the effective buffering of the free Ca(2+) concentration in it. The uptake of Ca(2+) occurred via an electrophoretic uniporter that has been molecularly identified only recently. Ca(2+) was then released through a Na(+)/Ca(2+) exchanger that has also been identified very recently (a H(+)/Ca(2+) antiporter has also been described in some mitochondrial types). In the matrix two TCA cycle dehydrogenases and pyruvate dehydrogenase phosphate phosphatase were found to be regulated by Ca(2+), providing a rationale for the Ca(2+) cycling process. The affinity of the uptake uniporter was found to be too low to efficiently regulate Ca(2+) in the low to mid nM concentration in the cytosol. However, a number of findings showed that energy linked transport of Ca(2+) did nevertheless occur in mitochondria in situ. The enigma was solved in the 1990s, when it was found that perimitochondrial Ca(2+) pools are created by the discharge of Ca(2+) from vicinal endoplasmic reticulum stores in which the concentration of Ca(2+) is high enough to satisfy the poor affinity of the uniporter. Thus, mitochondria have now regained a key role in the regulation of cytosolic Ca(2+) (not only of their own internal Ca(2+)).
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Affiliation(s)
- Ernesto Carafoli
- Venetian Institute of Molecular Medicine, University of Padova, Italy.
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52
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Hypoxic-ischemic injury in the developing brain: the role of reactive oxygen species originating in mitochondria. Neurol Res Int 2012; 2012:542976. [PMID: 22548167 PMCID: PMC3323863 DOI: 10.1155/2012/542976] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 11/12/2011] [Accepted: 11/22/2011] [Indexed: 02/01/2023] Open
Abstract
Mitochondrial dysfunction is the most fundamental mechanism of cell damage in cerebral hypoxia-ischemia and reperfusion. Mitochondrial respiratory chain (MRC) is increasingly recognized as a source for reactive oxygen species (ROS) in the postischemic tissue. Potentially, ROS originating in MRC can contribute to the reperfusion-driven oxidative stress, promoting mitochondrial membrane permeabilization. The loss of mitochondrial membranes integrity during reperfusion is considered as the major mechanism of secondary energy failure. This paper focuses on current data that support a pathogenic role of ROS originating from mitochondrial respiratory chain in the promotion of secondary energy failure and proposes potential therapeutic strategy against reperfusion-driven oxidative stress following hypoxia-ischemia-reperfusion injury of the developing brain.
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Stael S, Wurzinger B, Mair A, Mehlmer N, Vothknecht UC, Teige M. Plant organellar calcium signalling: an emerging field. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1525-42. [PMID: 22200666 PMCID: PMC3966264 DOI: 10.1093/jxb/err394] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This review provides a comprehensive overview of the established and emerging roles that organelles play in calcium signalling. The function of calcium as a secondary messenger in signal transduction networks is well documented in all eukaryotic organisms, but so far existing reviews have hardly addressed the role of organelles in calcium signalling, except for the nucleus. Therefore, a brief overview on the main calcium stores in plants-the vacuole, the endoplasmic reticulum, and the apoplast-is provided and knowledge on the regulation of calcium concentrations in different cellular compartments is summarized. The main focus of the review will be the calcium handling properties of chloroplasts, mitochondria, and peroxisomes. Recently, it became clear that these organelles not only undergo calcium regulation themselves, but are able to influence the Ca(2+) signalling pathways of the cytoplasm and the entire cell. Furthermore, the relevance of recent discoveries in the animal field for the regulation of organellar calcium signals will be discussed and conclusions will be drawn regarding potential homologous mechanisms in plant cells. Finally, a short overview on bacterial calcium signalling is included to provide some ideas on the question where this typically eukaryotic signalling mechanism could have originated from during evolution.
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Affiliation(s)
- Simon Stael
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Bernhard Wurzinger
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Andrea Mair
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Norbert Mehlmer
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
| | - Ute C. Vothknecht
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science (Munich) at the Department of Biology of the LMU Munich, D-81377 Munich, Germany
| | - Markus Teige
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
- To whom correspondence should be addressed.
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Bazil JN, Dash RK. A minimal model for the mitochondrial rapid mode of Ca²+ uptake mechanism. PLoS One 2011; 6:e21324. [PMID: 21731705 PMCID: PMC3121760 DOI: 10.1371/journal.pone.0021324] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 05/25/2011] [Indexed: 01/09/2023] Open
Abstract
Mitochondria possess a remarkable ability to rapidly accumulate and sequester Ca2+. One of the mechanisms responsible for this ability is believed to be the rapid mode (RaM) of Ca2+ uptake. Despite the existence of many models of mitochondrial Ca2+ dynamics, very few consider RaM as a potential mechanism that regulates mitochondrial Ca2+ dynamics. To fill this gap, a novel mathematical model of the RaM mechanism is developed herein. The model is able to simulate the available experimental data of rapid Ca2+ uptake in isolated mitochondria from both chicken heart and rat liver tissues with good fidelity. The mechanism is based on Ca2+ binding to an external trigger site(s) and initiating a brief transient of high Ca2+ conductivity. It then quickly switches to an inhibited, zero-conductive state until the external Ca2+ level is dropped below a critical value (∼100–150 nM). RaM's Ca2+- and time-dependent properties make it a unique Ca2+ transporter that may be an important means by which mitochondria take up Ca2+in situ and help enable mitochondria to decode cytosolic Ca2+ signals. Integrating the developed RaM model into existing models of mitochondrial Ca2+ dynamics will help elucidate the physiological role that this unique mechanism plays in mitochondrial Ca2+-homeostasis and bioenergetics.
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Affiliation(s)
- Jason N. Bazil
- Biotechnology and Bioengineering Center and Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Ranjan K. Dash
- Biotechnology and Bioengineering Center and Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
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Waldeck-Weiermair M, Jean-Quartier C, Rost R, Khan MJ, Vishnu N, Bondarenko AI, Imamura H, Malli R, Graier WF. Leucine zipper EF hand-containing transmembrane protein 1 (Letm1) and uncoupling proteins 2 and 3 (UCP2/3) contribute to two distinct mitochondrial Ca2+ uptake pathways. J Biol Chem 2011; 286:28444-55. [PMID: 21613221 PMCID: PMC3151087 DOI: 10.1074/jbc.m111.244517] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cytosolic Ca2+ signals are transferred into mitochondria over a huge concentration range. In our recent work we described uncoupling proteins 2 and 3 (UCP2/3) to be fundamental for mitochondrial uptake of high Ca2+ domains in mitochondria-ER junctions. On the other hand, the leucine zipper EF hand-containing transmembrane protein 1 (Letm1) was identified as a mitochondrial Ca2+/H+ antiporter that achieved mitochondrial Ca2+ sequestration at small Ca2+ increases. Thus, the contributions of Letm1 and UCP2/3 to mitochondrial Ca2+ uptake were compared in endothelial cells. Knock-down of Letm1 did not affect the UCP2/3-dependent mitochondrial uptake of intracellularly released Ca2+ but strongly diminished the transfer of entering Ca2+ into mitochondria, subsequently, resulting in a reduction of store-operated Ca2+ entry (SOCE). Knock-down of Letm1 and UCP2/3 did neither impact on cellular ATP levels nor the membrane potential. The enhanced mitochondrial Ca2+ signals in cells overexpressing UCP2/3 rescued SOCE upon Letm1 knock-down. In digitonin-permeabilized cells, Letm1 exclusively contributed to mitochondrial Ca2+ uptake at low Ca2+ conditions. Neither the Letm1- nor the UCP2/3-dependent mitochondrial Ca2+ uptake was affected by a knock-down of mRNA levels of mitochondrial calcium uptake 1 (MICU1), a protein that triggers mitochondrial Ca2+ uptake in HeLa cells. Our data indicate that Letm1 and UCP2/3 independently contribute to two distinct, mitochondrial Ca2+ uptake pathways in intact endothelial cells.
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Affiliation(s)
- Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Molecular and Cellular Physiology Research Unit, Center of Molecular Medicine, Medical University Graz, Harrachgasse 21/III, 8010 Graz, Austria
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McGEE AM, Baines CP. Complement 1q-binding protein inhibits the mitochondrial permeability transition pore and protects against oxidative stress-induced death. Biochem J 2011; 433:119-25. [PMID: 20950273 PMCID: PMC3512559 DOI: 10.1042/bj20101431] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Opening of the MPT (mitochondrial permeability transition) pore is a critical event in mitochondrial-mediated cell death. However, with the exception of CypD (cyclophilin D), the exact molecular composition of the MPT pore remains uncertain. C1qbp (complement 1q-binding protein) has recently been hypothesized to be an essential component of the MPT pore complex. To investigate whether C1qbp indeed plays a critical role in MPT and cell death, we conducted both gain-of-function and loss-of-function experiments in MEFs (mouse embryonic fibroblasts). We first confirmed that C1qbp is a soluble protein that localizes to the mitochondrial matrix in mouse cells and tissues. Similarly, overexpression of C1qbp in MEFs using an adenovirus resulted in its exclusive localization to mitochondria. To our surprise, increased C1qbp protein levels actually suppressed H2O2-induced MPT and cell death. Antithetically, knockdown of endogenous C1qbp with siRNA (small interfering RNA) sensitized the MEFs to H2O2-induced MPT and cell death. Moreover, we found that C1qbp could directly bind to CypD. Therefore C1qbp appears to act as an endogenous inhibitor of the MPT pore, most likely through binding to CypD, and thus protects cells against oxidative stress.
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Affiliation(s)
- Allison M. McGEE
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri, 65211, U.S.A
| | - Christopher P. Baines
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri, 65211, U.S.A
- Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, Missouri, 65211, U.S.A
- Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, Columbia, Missouri, 65211, U.S.A
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Abstract
The ability of mitochondria to sequester and retain divalent cations in the form of precipitates consisting of organic and inorganic moieties has been known for decades. Of these cations, Ca(2+) has emerged as a major player in both signal transduction and cell death mechanisms, and, as a consequence, the importance of mitochondria in these processes was soon recognized. Early studies showed considerable effort in identifying the mechanisms of Ca(2+) sequestration, precipitation and release by uncouplers of oxidative phosphorylation; however, relatively little information was obtained, and these processes were eventually taken for granted. Here, we re-examine: (a) the thermodynamic aspects of mitochondrial Ca(2+) uptake and release, (b) the insufficiently explained effect of uncouplers in inducing mitochondrial Ca(2+) release, (c) the thermodynamic effects of exogenously added adenine nucleotides on mitochondrial Ca(2+) uptake capacity and precipitate formation, and (d) the elusive nature of the Ca(2+) -phosphate precipitates formed in the mitochondrial matrix.
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Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences, Budapest, Hungary.
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58
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Abstract
Calcium is an extraordinarily versatile signaling ion, encoding cellular responses to a wide variety of external stimuli. In neurons, mitochondria can accumulate enormous amounts of calcium, with the consequence that mitochondrial calcium uptake, sequestration and release play pivotal roles in orchestrating calcium-dependent responses as diverse as gene transcription and cell death. In this review, we consider the basic chemistry of calcium as a 'sticky' cation, which leads to extremely high bound/free ratios, and discuss areas of current interest or controversy. Topics addressed include methodologies for measuring local intracellular calcium, mitochondrial calcium buffering and loading capacity, mitochondrially directed spatial calcium gradients, and the role of calcium overload-dependent mitochondrial dysfunction in glutamate-evoked excitotoxic injury and neurodegeneration. Finally, we consider the relationship between delayed calcium de-regulation, the mitochondrial permeability transition and the generation of reactive oxygen species, and propose a unified view of the 'source specificity' and 'calcium overload' models of N-methyl-d-aspartate (NMDA) receptor-dependent excitotoxicity. Non-NMDA receptor mechanisms of excitotoxicity are discussed briefly.
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Affiliation(s)
- Natalia B Pivovarova
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-4477, USA
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