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Crystal structure of MICU2 and comparison with MICU1 reveal insights into the uniporter gating mechanism. Proc Natl Acad Sci U S A 2019; 116:3546-3555. [PMID: 30755530 DOI: 10.1073/pnas.1817759116] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mitochondrial uniporter is a Ca2+-channel complex resident within the organelle's inner membrane. In mammalian cells the uniporter's activity is regulated by Ca2+ due to concerted action of MICU1 and MICU2, two paralogous, but functionally distinct, EF-hand Ca2+-binding proteins. Here we present the X-ray structure of the apo form of Mus musculus MICU2 at 2.5-Å resolution. The core structure of MICU2 is very similar to that of MICU1. It consists of two lobes, each containing one canonical Ca2+-binding EF-hand (EF1, EF4) and one structural EF-hand (EF2, EF3). Two molecules of MICU2 form a symmetrical dimer stabilized by highly conserved hydrophobic contacts between exposed residues of EF1 of one monomer and EF3 of another. Similar interactions stabilize MICU1 dimers, allowing exchange between homo- and heterodimers. The tight EF1-EF3 interface likely accounts for the structural and functional coupling between the Ca2+-binding sites in MICU1, MICU2, and their complex that leads to the previously reported Ca2+-binding cooperativity and dominant negative effect of mutation of the Ca2+-binding sites in either protein. The N- and C-terminal segments of the two proteins are distinctly different. In MICU2 the C-terminal helix is significantly longer than in MICU1, and it adopts a more rigid structure. MICU2's C-terminal helix is dispensable in vitro for its interaction with MICU1 but required for MICU2's function in cells. We propose that in the MICU1-MICU2 oligomeric complex the C-terminal helices of both proteins form a central semiautonomous assembly which contributes to the gating mechanism of the uniporter.
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52
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Phillips CB, Tsai CW, Tsai MF. The conserved aspartate ring of MCU mediates MICU1 binding and regulation in the mitochondrial calcium uniporter complex. eLife 2019; 8:41112. [PMID: 30638448 PMCID: PMC6347451 DOI: 10.7554/elife.41112] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/07/2019] [Indexed: 01/09/2023] Open
Abstract
The mitochondrial calcium uniporter is a Ca2+ channel that regulates intracellular Ca2+ signaling, oxidative phosphorylation, and apoptosis. It contains the pore-forming MCU protein, which possesses a DIME sequence thought to form a Ca2+ selectivity filter, and also regulatory EMRE, MICU1, and MICU2 subunits. To properly carry out physiological functions, the uniporter must stay closed in resting conditions, becoming open only when stimulated by intracellular Ca2+ signals. This Ca2+-dependent activation, known to be mediated by MICU subunits, is not well understood. Here, we demonstrate that the DIME-aspartate mediates a Ca2+-modulated electrostatic interaction with MICU1, forming an MICU1 contact interface with a nearby Ser residue at the cytoplasmic entrance of the MCU pore. A mutagenesis screen of MICU1 identifies two highly-conserved Arg residues that might contact the DIME-Asp. Perturbing MCU-MICU1 interactions elicits unregulated, constitutive Ca2+ flux into mitochondria. These results indicate that MICU1 confers Ca2+-dependent gating of the uniporter by blocking/unblocking MCU.
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Affiliation(s)
| | - Chen-Wei Tsai
- Department of Biochemistry, Brandeis University, Waltham, United States.,Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Ming-Feng Tsai
- Department of Biochemistry, Brandeis University, Waltham, United States.,Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States
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53
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Paillard M, Csordás G, Huang KT, Várnai P, Joseph SK, Hajnóczky G. MICU1 Interacts with the D-Ring of the MCU Pore to Control Its Ca 2+ Flux and Sensitivity to Ru360. Mol Cell 2018; 72:778-785.e3. [PMID: 30454562 PMCID: PMC6251499 DOI: 10.1016/j.molcel.2018.09.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/20/2018] [Accepted: 09/06/2018] [Indexed: 01/04/2023]
Abstract
Proper control of the mitochondrial Ca2+ uniporter's pore (MCU) is required to allow Ca2+-dependent activation of oxidative metabolism and to avoid mitochondrial Ca2+ overload and cell death. The MCU's gatekeeping and cooperative activation is mediated by the Ca2+-sensing MICU1 protein, which has been proposed to form dimeric complexes anchored to the EMRE scaffold of MCU. We unexpectedly find that MICU1 suppresses inhibition of MCU by ruthenium red/Ru360, which bind to MCU's DIME motif, the selectivity filter. This led us to recognize in MICU1's sequence a putative DIME interacting domain (DID), which is required for both gatekeeping and cooperative activation of MCU and for cell survival. Thus, we propose that MICU1 has to interact with the D-ring formed by the DIME domains in MCU to control the uniporter.
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Affiliation(s)
- Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kai-Ting Huang
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Peter Várnai
- Department of Physiology, Semmelweis University, Budapest, 1094 Hungary
| | - Suresh K Joseph
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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54
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Basso E, Rigotto G, Zucchetti AE, Pozzan T. Slow activation of fast mitochondrial Ca 2+ uptake by cytosolic Ca 2. J Biol Chem 2018; 293:17081-17094. [PMID: 30228190 DOI: 10.1074/jbc.ra118.002332] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 09/06/2018] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniporter (MCU) is a tightly controlled process that sustains cell functions mainly by fine-tuning oxidative metabolism to cellular needs. The kinetics of Ca2+ fluxes across the mitochondrial membranes have been studied both in vitro and in vivo for many years, and the discovery of the molecular components of the MCU has further clarified that this Ca2+ uptake mechanism is based on a complex system subject to elaborate layers of controls. Alterations in the speed or capacity of the in-and-out pathways can have detrimental consequences for both the organelle and the cell, impairing cellular metabolism and ultimately causing cell death. Here, we report that pretreatment of deenergized mitochondria with low-micromolar Ca2+ concentrations for a few minutes markedly increases the speed of mitochondrial Ca2+ uptake upon re-addition of an oxidizable substrate. We found that this phenomenon is sensitive to alterations in the level of the MCU modulator proteins mitochondrial calcium uptake 1 (MICU1) and 2 (MICU2), and is accompanied by changes in the association of MICU1-MICU2 complexes with MCU. This increased Ca2+ uptake capacity, occurring under conditions mimicking those during ischemia/reperfusion in vivo, could lead to a massive amount of Ca2+ entering the mitochondrial matrix even at relatively low levels of cytosolic Ca2+ We conclude that the phenomenon uncovered here represents a potential threat of mitochondrial Ca2+ overload to the cell.
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Affiliation(s)
- Emy Basso
- From the National Research Council, Department of Biomedical Science, Neuroscience Institute (Padua Section), 35131 Padua, Italy,
| | - Giulia Rigotto
- the Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Andrés E Zucchetti
- the Institut Curie, PSL Research University, INSERM, U932, 26 rue d'Ulm, 75248 Paris Cedex 05, France, and
| | - Tullio Pozzan
- From the National Research Council, Department of Biomedical Science, Neuroscience Institute (Padua Section), 35131 Padua, Italy.,the Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,the Venetian Institute of Molecular Medicine, 35129 Padua, Italy
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55
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Wang M, Teng Y. Genome-wide identification and analysis of MICU genes in land plants and their potential role in calcium stress. Gene 2018; 670:174-181. [PMID: 29852202 DOI: 10.1016/j.gene.2018.05.102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/09/2018] [Accepted: 05/25/2018] [Indexed: 11/24/2022]
Abstract
Mitochondrial calcium uptake (MICU) plays a vital role in the regulation of mitochondrial calcium homeostasis, and, consequently, influences calcium signaling transduction. Although genes involved in mitochondrial calcium uptake have been well studied in animals, less is known about their ubiquity and function in plants. In this study, we identified 96 MICU genes in land plants. On the basis of phylogenetic analysis of MICU proteins, they were classified into three clades: MICU from eudicots (Clade I), from monocots (Clade II), and from a basal angiosperm, a bryophyte, and a lycophyte (Clade III). Pairwise identity analysis across all MICU proteins showed that they are highly conserved among land plants at the protein level. Conserved motif analysis showed that most MICU proteins contained three EF-hands, and an additional EF-hand motif first identified in the MICU of Arabidopsis thaliana but not mammals was found in all 96 putative MICU proteins. This suggests that a cellular pathway of calcium uptake and signaling that requires three EF-hand motifs is evolutionarily conserved in plants. In addition, we discovered that MICU-defective mutants of Arabidopsis thaliana exhibited longer roots than wild-type under high calcium stress. Concurrently, the mRNA transcription levels of MICU were decreased under high calcium conditions. These results suggest that loss-of-function mutations of MICU may have potential roles in helping plants resist high calcium stress. This study provides clues to the possible role of plant MICU in mitochondrial calcium uptake, as well as useful information to support further studies on MICU function in plants.
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Affiliation(s)
- Mengyun Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310016, People's Republic of China
| | - Yibo Teng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310016, People's Republic of China.
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56
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Nemani N, Shanmughapriya S, Madesh M. Molecular regulation of MCU: Implications in physiology and disease. Cell Calcium 2018; 74:86-93. [PMID: 29980025 PMCID: PMC6119482 DOI: 10.1016/j.ceca.2018.06.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/04/2018] [Accepted: 06/25/2018] [Indexed: 01/17/2023]
Abstract
Ca2+ flux across the inner mitochondrial membrane (IMM) regulates cellular bioenergetics, intra-cellular cytoplasmic Ca2+ signals, and various cell death pathways. Ca2+ entry into the mitochondria occurs due to the highly negative membrane potential (ΔΨm) through a selective inward rectifying MCU channel. In addition to being regulated by various mitochondrial matrix resident proteins such as MICUs, MCUb, MCUR1 and EMRE, the channel is transcriptionally regulated by upstream Ca2+ cascade, post transnational modification and by divalent cations. The mode of regulation either inhibits or enhances MCU channel activity and thus regulates mitochondrial metabolism and cell fate.
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Affiliation(s)
- Neeharika Nemani
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Santhanam Shanmughapriya
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Muniswamy Madesh
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Center for Precision Medicine, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229.
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57
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MICU1 imparts the mitochondrial uniporter with the ability to discriminate between Ca 2+ and Mn 2+. Proc Natl Acad Sci U S A 2018; 115:E7960-E7969. [PMID: 30082385 DOI: 10.1073/pnas.1807811115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial uniporter is a Ca2+-activated Ca2+ channel complex that displays exceptionally high conductance and selectivity. Here, we report cellular metal toxicity screens highlighting the uniporter's role in Mn2+ toxicity. Cells lacking the pore-forming uniporter subunit, MCU, are more resistant to Mn2+ toxicity, while cells lacking the Ca2+-sensing inhibitory subunit, MICU1, are more sensitive than the wild type. Consistent with these findings, Caenorhabditis elegans lacking the uniporter's pore have increased resistance to Mn2+ toxicity. The chemical-genetic interaction between uniporter machinery and Mn2+ toxicity prompted us to hypothesize that Mn2+ can indeed be transported by the uniporter's pore, but this transport is prevented by MICU1. To this end, we demonstrate that, in the absence of MICU1, both Mn2+ and Ca2+ can pass through the uniporter, as evidenced by mitochondrial Mn2+ uptake assays, mitochondrial membrane potential measurements, and mitoplast electrophysiology. We show that Mn2+ does not elicit the conformational change in MICU1 that is physiologically elicited by Ca2+, preventing Mn2+ from inducing the pore opening. Our work showcases a mechanism by which a channel's auxiliary subunit can contribute to its apparent selectivity and, furthermore, may have implications for understanding how manganese contributes to neurodegenerative disease.
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58
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Nguyen NX, Armache JP, Lee C, Yang Y, Zeng W, Mootha VK, Cheng Y, Bai XC, Jiang Y. Cryo-EM structure of a fungal mitochondrial calcium uniporter. Nature 2018; 559:570-574. [PMID: 29995855 PMCID: PMC6063787 DOI: 10.1038/s41586-018-0333-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 05/15/2018] [Indexed: 11/09/2022]
Abstract
The mitochondrial calcium uniporter (MCU) is a highly selective calcium channel localized to the inner mitochondrial membrane. Here, we describe the structure of an MCU orthologue from the fungus Neosartorya fischeri (NfMCU) determined to 3.8 Å resolution by phase-plate cryo-electron microscopy. The channel is a homotetramer with two-fold symmetry in its amino-terminal domain (NTD) that adopts a similar structure to that of human MCU. The NTD assembles as a dimer of dimers to form a tetrameric ring that connects to the transmembrane domain through an elongated coiled-coil domain. The ion-conducting pore domain maintains four-fold symmetry, with the selectivity filter positioned at the start of the pore-forming TM2 helix. The aspartate and glutamate sidechains of the conserved DIME motif are oriented towards the central axis and separated by one helical turn. The structure of NfMCU offers insights into channel assembly, selective calcium permeation, and inhibitor binding.
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Affiliation(s)
- Nam X Nguyen
- Howard Hughes Medical Institute and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jean-Paul Armache
- Howard Hughes Medical Institute and Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Changkeun Lee
- Howard Hughes Medical Institute and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Amgen Discovery Research, Cambridge, MA, USA
| | - Yi Yang
- Howard Hughes Medical Institute and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Weizhong Zeng
- Howard Hughes Medical Institute and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Broad Institute, Cambridge, MA, USA
| | - Yifan Cheng
- Howard Hughes Medical Institute and Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Youxing Jiang
- Howard Hughes Medical Institute and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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59
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Tsai CW, Tsai MF. Electrical recordings of the mitochondrial calcium uniporter in Xenopus oocytes. J Gen Physiol 2018; 150:1035-1043. [PMID: 29891485 PMCID: PMC6028504 DOI: 10.1085/jgp.201812015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/22/2018] [Indexed: 11/21/2022] Open
Abstract
The mitochondrial calcium uniporter is a Ca2+ channel that has been hard to characterize electrophysiologically. Tsai and Tsai establish a method that permits efficient electrophysiological recordings of the human uniporter in Xenopus oocytes and demonstrate characteristic uniporter behaviour. The mitochondrial calcium uniporter is a multisubunit Ca2+ channel that mediates mitochondrial Ca2+ uptake, a cellular process crucial for the regulation of oxidative phosphorylation, intracellular Ca2+ signaling, and apoptosis. In the last few years, genes encoding uniporter proteins have been identified, but a lack of efficient tools for electrophysiological recordings has hindered quantitative analysis required to determine functional mechanisms of this channel complex. Here, we redirected Ca2+-conducting subunits (MCU and EMRE) of the human uniporter to the plasma membrane of Xenopus oocytes. Two-electrode voltage clamp reveals inwardly rectifying Ca2+ currents blocked by a potent inhibitor, Ru360 (half maximal inhibitory concentration, ~4 nM), with a divalent cation conductivity of Ca2+ > Sr2+ > Ba2+, Mn2+, and Mg2+. Patch clamp recordings further reveal macroscopic and single-channel Ca2+ currents sensitive to Ru360. These electrical phenomena were abolished by mutations that perturb MCU-EMRE interactions or disrupt a Ca2+-binding site in the pore. Altogether, this work establishes a robust method that enables deep mechanistic scrutiny of the uniporter using classical strategies in ion channel electrophysiology.
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Affiliation(s)
- Chen-Wei Tsai
- Department of Biochemistry, Brandeis University, Waltham, MA
| | - Ming-Feng Tsai
- Department of Biochemistry, Brandeis University, Waltham, MA .,Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO.,Howard Hughes Medical Institute, Chevy Chase, MD
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60
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Ren T, Wang J, Zhang H, Yuan P, Zhu J, Wu Y, Huang Q, Guo X, Zhang J, Ji L, Li J, Zhang H, Yang H, Xing J. MCUR1-Mediated Mitochondrial Calcium Signaling Facilitates Cell Survival of Hepatocellular Carcinoma via Reactive Oxygen Species-Dependent P53 Degradation. Antioxid Redox Signal 2018; 28:1120-1136. [PMID: 28938844 DOI: 10.1089/ars.2017.6990] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
AIMS Levels of the mitochondrial calcium uniporter regulator 1 (MCUR1) increases during development of hepatocellular carcinoma (HCC). However, mechanisms of how mitochondrial Ca2+ homeostasis is modulated and its function remain limited in cancers. RESULTS MCUR1 was frequently upregulated in HCC cells to enhance the Ca2+ uptake into mitochondria in an MCU-dependent manner, which significantly facilitated cell survival by inhibiting mitochondria-dependent intrinsic apoptosis and promoting proliferation of HCC cells, and thus led to poor prognosis. In vivo assay confirmed these results, indicating that overexpressed MCUR1 notably decreased the fraction of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells and increased the positive Ki67 staining in xenograft tumors, while reduced MCUR1 expression was associated with impaired growth capacity of HCC cells in nude mice. The survival advantage conferred by MCUR1-mediated mitochondrial Ca2+ uptake was majorly caused by elevated production of mitochondrial reactive oxygen species and subsequent AKT/MDM2- induced P53 degradation, which regulated the expression level of apoptosis-related molecules and cell cycle-related molecules. Treatment of mitochondrial Ca2+-buffering protein parvalbumin remarkably inhibited the growth of HCC cells. Conclusions and Innovation: Our study provides evidence supporting a possible tumor-promoting role for MCUR1-mediated mitochondrial Ca2+ uptake and uncovers a mechanistic understanding that links change of mitochondrial Ca2+ homeostasis to cancer cell survival, which suggests a potential novel therapeutic target for HCC. Antioxid. Redox Signal. 28, 1120-1136.
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Affiliation(s)
- Tingting Ren
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Jiaojiao Wang
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Hui Zhang
- 2 Department of Pain Treatment, Tangdu Hospital, Fourth Military Medical University , Xi'an, China
| | - Peng Yuan
- 2 Department of Pain Treatment, Tangdu Hospital, Fourth Military Medical University , Xi'an, China
| | - Jianjun Zhu
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Yousheng Wu
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Qichao Huang
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Xu Guo
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Jing Zhang
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Lele Ji
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Jibin Li
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
| | - Hongxin Zhang
- 2 Department of Pain Treatment, Tangdu Hospital, Fourth Military Medical University , Xi'an, China
| | - Hushan Yang
- 3 Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - Jinliang Xing
- 1 State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University , Xi'an, China
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61
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Mammucari C, Raffaello A, Vecellio Reane D, Gherardi G, De Mario A, Rizzuto R. Mitochondrial calcium uptake in organ physiology: from molecular mechanism to animal models. Pflugers Arch 2018. [PMID: 29541860 PMCID: PMC6060757 DOI: 10.1007/s00424-018-2123-2] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondrial Ca2+ is involved in heterogeneous functions, ranging from the control of metabolism and ATP production to the regulation of cell death. In addition, mitochondrial Ca2+ uptake contributes to cytosolic [Ca2+] shaping thus impinging on specific Ca2+-dependent events. Mitochondrial Ca2+ concentration is controlled by influx and efflux pathways: the former controlled by the activity of the mitochondrial Ca2+ uniporter (MCU), the latter by the Na+/Ca2+ exchanger (NCLX) and the H+/Ca2+ (mHCX) exchanger. The molecular identities of MCU and of NCLX have been recently unraveled, thus allowing genetic studies on their physiopathological relevance. After a general framework on the significance of mitochondrial Ca2+ uptake, this review discusses the structure of the MCU complex and the regulation of its activity, the importance of mitochondrial Ca2+ signaling in different physiological settings, and the consequences of MCU modulation on organ physiology.
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Affiliation(s)
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | | | - Gaia Gherardi
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Agnese De Mario
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padua, Italy.
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62
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Gottschalk B, Klec C, Waldeck-Weiermair M, Malli R, Graier WF. Intracellular Ca 2+ release decelerates mitochondrial cristae dynamics within the junctions to the endoplasmic reticulum. Pflugers Arch 2018. [PMID: 29527615 PMCID: PMC6047742 DOI: 10.1007/s00424-018-2133-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mitochondria are multifunctional organelles that essentially contribute to cell signaling by sophisticated mechanisms of communications. Live cell imaging studies showed that mitochondria are dynamic and complex structures that form ramified networks by directed movements, fission, and fusion events. There is emerging evidence that the morphology of mitochondria determines cellular functions and vice versa. Several intracellular signaling pathways and messengers including Ca2+ dynamically influence the architecture of mitochondria. Because electron microscopy cannot be utilized for an assessment of dynamics of mitochondrial morphology in intact cells, most studies were performed using wide-field or laser confocal fluorescence microscopies that, due to limitations of their spatial resolution, do not allow investigating sub-mitochondrial structures. Accordingly, our understanding of the dynamics of substructures of mitochondria is quite limited. Here, we present a robust super-resolution method to quantify the dynamics of mitochondrial cristae, the main substructures of the inner mitochondrial membrane, exploiting structured illumination microscopy (SIM). We observed that knockdown of the dynamin-like 120-kDa protein, which is encoded by the OPA1 gene, specifically reduces the dynamics of the mitochondrial cristae membranes (CM), while the inner boundary membrane (IBM) remained flexible. We further used dual color SIM to quantify the dynamics of CM in the junction between mitochondria and the endoplasmic reticulum (ER; mitochondrial associated membranes, MAMs). Intracellular Ca2+ release spatially reduced CM-dynamics in MAMs. Moreover, CM-dynamics was independent from matrix Ca2+ signal. Our data suggest that local Ca2+ signals specifically control CM-dynamics and structure to facilitate a well-balanced functional (Ca2+) interplay between mitochondria and the ER.
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Affiliation(s)
- Benjamin Gottschalk
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Christinae Klec
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Markus Waldeck-Weiermair
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
- BioTechMed, Graz, Austria
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria.
- BioTechMed, Graz, Austria.
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63
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The MCU complex in cell death. Cell Calcium 2018; 69:73-80. [DOI: 10.1016/j.ceca.2017.08.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 01/01/2023]
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64
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Alevriadou BR, Shanmughapriya S, Patel A, Stathopulos PB, Madesh M. Mitochondrial Ca 2+ transport in the endothelium: regulation by ions, redox signalling and mechanical forces. J R Soc Interface 2017; 14:rsif.2017.0672. [PMID: 29237825 DOI: 10.1098/rsif.2017.0672] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/16/2017] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca2+) transport by mitochondria is an important component of the cell Ca2+ homeostasis machinery in metazoans. Ca2+ uptake by mitochondria is a major determinant of bioenergetics and cell fate. Mitochondrial Ca2+ uptake occurs via the mitochondrial Ca2+ uniporter (MCU) complex, an inner mitochondrial membrane protein assembly consisting of the MCU Ca2+ channel, as its core component, and the MCU complex regulatory/auxiliary proteins. In this review, we summarize the current knowledge on the molecular nature of the MCU complex and its regulation by intra- and extramitochondrial levels of divalent ions and reactive oxygen species (ROS). Intracellular Ca2+ concentration ([Ca2+]i), mitochondrial Ca2+ concentration ([Ca2+]m) and mitochondrial ROS (mROS) are intricately coupled in regulating MCU activity. Here, we highlight the contribution of MCU activity to vascular endothelial cell (EC) function. Besides the ionic and oxidant regulation, ECs are continuously exposed to haemodynamic forces (either pulsatile or oscillatory fluid mechanical shear stresses, depending on the precise EC location within the arteries). Thus, we also propose an EC mechanotransduction-mediated regulation of MCU activity in the context of vascular physiology and atherosclerotic vascular disease.
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Affiliation(s)
- B Rita Alevriadou
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA .,Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH 43210, USA.,Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Santhanam Shanmughapriya
- Department of Medical Genetics and Molecular Biochemistry, Temple University, Philadelphia, PA 19140, USA.,Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Akshar Patel
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH 43210, USA.,Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada N6A 5C1
| | - Muniswamy Madesh
- Department of Medical Genetics and Molecular Biochemistry, Temple University, Philadelphia, PA 19140, USA .,Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
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65
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Tissue-Specific Mitochondrial Decoding of Cytoplasmic Ca 2+ Signals Is Controlled by the Stoichiometry of MICU1/2 and MCU. Cell Rep 2017; 18:2291-2300. [PMID: 28273446 PMCID: PMC5760244 DOI: 10.1016/j.celrep.2017.02.032] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/29/2016] [Accepted: 02/09/2017] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial Ca2+ uptake through the Ca2+ uniporter supports cell functions, including oxidative metabolism, while meeting tissue-specific calcium signaling patterns and energy needs. The molecular mechanisms underlying tissue-specific control of the uniporter are unknown. Here, we investigated a possible role for tissue-specific stoichiometry between the Ca2+-sensing regulators (MICUs) and pore unit (MCU) of the uniporter. Low MICU1:MCU protein ratio lowered the [Ca2+] threshold for Ca2+ uptake and activation of oxidative metabolism but decreased the cooperativity of uniporter activation in heart and skeletal muscle compared to liver. In MICU1-overexpressing cells, MICU1 was pulled down by MCU proportionally to MICU1 overexpression, suggesting that MICU1:MCU protein ratio directly reflected their association. Overexpressing MICU1 in the heart increased MICU1:MCU ratio, leading to liver-like mitochondrial Ca2+ uptake phenotype and cardiac contractile dysfunction. Thus, the proportion of MICU1-free and MICU1-associated MCU controls these tissue-specific uniporter phenotypes and downstream Ca2+ tuning of oxidative metabolism.
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66
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Liu JC, Parks RJ, Liu J, Stares J, Rovira II, Murphy E, Finkel T. The In Vivo Biology of the Mitochondrial Calcium Uniporter. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:49-63. [PMID: 28551781 DOI: 10.1007/978-3-319-55330-6_3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The identification of the molecular composition of the mitochondrial calcium uniporter has allowed for the genetic manipulation of its components and the creation of various in vivo genetic models. Here, we review the initial attempts to modulate the expression of components of the calcium uniporter in a range of organisms from plants to mammals. This analysis has confirmed the strict requirement for the uniporter for in vivo mitochondrial calcium uptake and for maintaining mitochondrial calcium homeostasis. We further discuss the physiological effects following genetic manipulation of the uniporter on tissue bioenergetics and the threshold for cell death. Finally, we analyze the limited information regarding the role of various uniporter components in human disease.
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Affiliation(s)
- Julia C Liu
- Center for Molecular Medicine, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Randi J Parks
- Systems Biology Center, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Jie Liu
- Center for Molecular Medicine, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Justin Stares
- Center for Molecular Medicine, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Ilsa I Rovira
- Center for Molecular Medicine, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Elizabeth Murphy
- Systems Biology Center, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Toren Finkel
- Center for Molecular Medicine, National Heart Lung and Blood Institute, Bethesda, MD, 20892, USA. .,NIH, Bldg 10/CRC 5-3330, Bethesda, MD, 20892, USA.
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67
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Mammucari C, Gherardi G, Rizzuto R. Structure, Activity Regulation, and Role of the Mitochondrial Calcium Uniporter in Health and Disease. Front Oncol 2017; 7:139. [PMID: 28740830 PMCID: PMC5502327 DOI: 10.3389/fonc.2017.00139] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/19/2017] [Indexed: 01/09/2023] Open
Abstract
Mitochondrial Ca2+ uptake plays a pivotal role both in cell energy balance and in cell fate determination. Studies on the role of mitochondrial Ca2+ signaling in pathophysiology have been favored by the identification of the genes encoding the mitochondrial calcium uniporter (MCU) and its regulatory subunits. Thus, research carried on in the last years on one hand has determined the structure of the MCU complex and its regulation, on the other has uncovered the consequences of dysregulated mitochondrial Ca2+ signaling in cell and tissue homeostasis. Whether mitochondrial Ca2+ uptake can be exploited as a weapon to counteract cancer progression is debated. In this review, we summarize recent research on the molecular structure of the MCU, the regulatory mechanisms that control its activity and its relevance in pathophysiology, focusing in particular on its role in cancer progression.
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Affiliation(s)
| | - Gaia Gherardi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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68
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Kamer KJ, Grabarek Z, Mootha VK. High-affinity cooperative Ca 2+ binding by MICU1-MICU2 serves as an on-off switch for the uniporter. EMBO Rep 2017; 18:1397-1411. [PMID: 28615291 DOI: 10.15252/embr.201643748] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/01/2017] [Accepted: 05/04/2017] [Indexed: 01/18/2023] Open
Abstract
The mitochondrial calcium uniporter is a Ca2+-activated Ca2+ channel that is essential for dynamic modulation of mitochondrial function in response to cellular Ca2+ signals. It is regulated by two paralogous EF-hand proteins-MICU1 and MICU2, but the mechanism is unknown. Here, we demonstrate that both MICU1 and MICU2 are stabilized by Ca2+ We reconstitute the MICU1-MICU2 heterodimer and demonstrate that it binds Ca2+ cooperatively with high affinity. We discover that both MICU1 and MICU2 exhibit affinity for the mitochondria-specific lipid cardiolipin. We determine the minimum Ca2+ concentration required for disinhibition of the uniporter in permeabilized cells and report a close match with the Ca2+-binding affinity of MICU1-MICU2. We conclude that cooperative, high-affinity interaction of the MICU1-MICU2 complex with Ca2+ serves as an on-off switch, leading to a tightly controlled channel, capable of responding directly to cytosolic Ca2+ signals.
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Affiliation(s)
- Kimberli J Kamer
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Zenon Grabarek
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA .,Department of Systems Biology, Harvard Medical School, Boston, MA, USA.,Broad Institute, Cambridge, MA, USA
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69
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Chakraborty PK, Mustafi SB, Xiong X, Dwivedi SKD, Nesin V, Saha S, Zhang M, Dhanasekaran D, Jayaraman M, Mannel R, Moore K, McMeekin S, Yang D, Zuna R, Ding K, Tsiokas L, Bhattacharya R, Mukherjee P. MICU1 drives glycolysis and chemoresistance in ovarian cancer. Nat Commun 2017; 8:14634. [PMID: 28530221 PMCID: PMC5477507 DOI: 10.1038/ncomms14634] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 01/18/2017] [Indexed: 12/18/2022] Open
Abstract
Cancer cells actively promote aerobic glycolysis to sustain their metabolic requirements through mechanisms not always clear. Here, we demonstrate that the gatekeeper of mitochondrial Ca2+ uptake, Mitochondrial Calcium Uptake 1 (MICU1/CBARA1) drives aerobic glycolysis in ovarian cancer. We show that MICU1 is overexpressed in a panel of ovarian cancer cell lines and that MICU1 overexpression correlates with poor overall survival (OS). Silencing MICU1 in vitro increases oxygen consumption, decreases lactate production, inhibits clonal growth, migration and invasion of ovarian cancer cells, whereas silencing in vivo inhibits tumour growth, increases cisplatin efficacy and OS. Mechanistically, silencing MICU1 activates pyruvate dehydrogenase (PDH) by stimulating the PDPhosphatase-phosphoPDH-PDH axis. Forced-expression of MICU1 in normal cells phenocopies the metabolic aberrations of malignant cells. Consistent with the in vitro and in vivo findings we observe a significant correlation between MICU1 and pPDH (inactive form of PDH) expression with poor prognosis. Thus, MICU1 could serve as an important therapeutic target to normalize metabolic aberrations responsible for poor prognosis in ovarian cancer.
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Affiliation(s)
- Prabir K. Chakraborty
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Soumyajit Banerjee Mustafi
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Xunhao Xiong
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Shailendra Kumar Dhar Dwivedi
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Vasyl Nesin
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma 73104, USA
| | - Sounik Saha
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Min Zhang
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania 15261, USA
| | - Danny Dhanasekaran
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Muralidharan Jayaraman
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma 73104, USA
| | - Robert Mannel
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Kathleen Moore
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Scott McMeekin
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Da Yang
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania 15261, USA
| | - Rosemary Zuna
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Kai Ding
- College of Public Health, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Leonidas Tsiokas
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma 73104, USA
| | - Resham Bhattacharya
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Priyabrata Mukherjee
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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70
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Marchi S, Patergnani S, Missiroli S, Morciano G, Rimessi A, Wieckowski MR, Giorgi C, Pinton P. Mitochondrial and endoplasmic reticulum calcium homeostasis and cell death. Cell Calcium 2017; 69:62-72. [PMID: 28515000 DOI: 10.1016/j.ceca.2017.05.003] [Citation(s) in RCA: 390] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/04/2017] [Accepted: 05/04/2017] [Indexed: 12/12/2022]
Abstract
The endoplasmic reticulum (ER) and mitochondria cannot be considered as static structures, as they intimately communicate, forming very dynamic platforms termed mitochondria-associated membranes (MAMs). In particular, the ER transmits proper Ca2+ signals to mitochondria, which decode them into specific inputs to regulate essential functions, including metabolism, energy production and apoptosis. Here, we will describe the different molecular players involved in the transfer of Ca2+ ions from the ER lumen to the mitochondrial matrix and how modifications in both ER-mitochondria contact sites and Ca2+ signaling can alter the cell death execution program.
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Affiliation(s)
- Saverio Marchi
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Simone Patergnani
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Sonia Missiroli
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Giampaolo Morciano
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Alessandro Rimessi
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | | | - Carlotta Giorgi
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Dept. of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy.
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71
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Liao Y, Dong Y, Cheng J. The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders. Int J Mol Sci 2017; 18:ijms18020248. [PMID: 28208618 PMCID: PMC5343785 DOI: 10.3390/ijms18020248] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 11/16/2022] Open
Abstract
The mitochondrial calcium uniporter (MCU)-a calcium uniporter on the inner membrane of mitochondria-controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP); however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders.
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Affiliation(s)
- Yajin Liao
- The Brain Science Center, Beijing Institute of Basic Medical Sciences, No. 27 Taiping Road, Haidian District, Beijing 100039, China.
- The State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Yuan Dong
- Department of Biochemistry, Qingdao University Medical College, Qingdao 266071, China.
| | - Jinbo Cheng
- The State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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72
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Mishra J, Jhun BS, Hurst S, O-Uchi J, Csordás G, Sheu SS. The Mitochondrial Ca 2+ Uniporter: Structure, Function, and Pharmacology. Handb Exp Pharmacol 2017; 240:129-156. [PMID: 28194521 PMCID: PMC5554456 DOI: 10.1007/164_2017_1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Mitochondrial Ca2+ uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca2+ uptake and our current understanding of mitochondrial Ca2+ homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca2+ uniporter complex.
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Affiliation(s)
- Jyotsna Mishra
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 543D, Philadelphia, PA, 19107, USA
| | - Bong Sook Jhun
- Cardiovascular Research Center, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Stephen Hurst
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 543D, Philadelphia, PA, 19107, USA
| | - Jin O-Uchi
- Cardiovascular Research Center, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA.
| | - György Csordás
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, 19107, USA.
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, 1020 Locust Street, Suite 543D, Philadelphia, PA, 19107, USA.
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73
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Malli R, Graier WF. The Role of Mitochondria in the Activation/Maintenance of SOCE: The Contribution of Mitochondrial Ca 2+ Uptake, Mitochondrial Motility, and Location to Store-Operated Ca 2+ Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:297-319. [PMID: 28900921 DOI: 10.1007/978-3-319-57732-6_16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In most cell types, the depletion of internal Ca2+ stores triggers the activation of Ca2+ entry. This crucial phenomenon is known since the 1980s and referred to as store-operated Ca2+ entry (SOCE). With the discoveries of the stromal-interacting molecules (STIMs) and the Ca2+-permeable Orai channels as the long-awaited molecular constituents of SOCE, the role of mitochondria in controlling the activity of this particular Ca2+ entry pathway is kind of buried in oblivion. However, the capability of mitochondria to locally sequester Ca2+ at sites of Ca2+ release and entry was initially supposed to rule SOCE by facilitating the Ca2+ depletion of the endoplasmic reticulum and removing entering Ca2+ from the Ca2+-inhibitable channels, respectively. Moreover, the central role of these organelles in controlling the cellular energy metabolism has been linked to the activity of SOCE. Nevertheless, the exact molecular mechanisms by which mitochondria actually determine SOCE are still pretty obscure. In this essay we describe the complexity of the mitochondrial Ca2+ uptake machinery and its regulation, molecular components, and properties, which open new ways for scrutinizing the contribution of mitochondria to SOCE. Moreover, data concerning the variability of the morphology and cellular distribution of mitochondria as putative determinants of SOCE activation, maintenance, and termination are summarized.
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Affiliation(s)
- Roland Malli
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010, Graz, Austria
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010, Graz, Austria.
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74
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A MICU1 Splice Variant Confers High Sensitivity to the Mitochondrial Ca 2+ Uptake Machinery of Skeletal Muscle. Mol Cell 2016; 64:760-773. [PMID: 27818145 DOI: 10.1016/j.molcel.2016.10.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/06/2016] [Accepted: 09/30/2016] [Indexed: 01/28/2023]
Abstract
Skeletal muscle is a dynamic organ, characterized by an incredible ability to rapidly increase its rate of energy consumption to sustain activity. Muscle mitochondria provide most of the ATP required for contraction via oxidative phosphorylation. Here we found that skeletal muscle mitochondria express a unique MCU complex containing an alternative splice isoform of MICU1, MICU1.1, characterized by the addition of a micro-exon that is sufficient to greatly modify the properties of the MCU. Indeed, MICU1.1 binds Ca2+ one order of magnitude more efficiently than MICU1 and, when heterodimerized with MICU2, activates MCU current at lower Ca2+ concentrations than MICU1-MICU2 heterodimers. In skeletal muscle in vivo, MICU1.1 is required for sustained mitochondrial Ca2+ uptake and ATP production. These results highlight a novel mechanism of the molecular plasticity of the MCU Ca2+ uptake machinery that allows skeletal muscle mitochondria to be highly responsive to sarcoplasmic [Ca2+] responses.
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75
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Raffaello A, Mammucari C, Gherardi G, Rizzuto R. Calcium at the Center of Cell Signaling: Interplay between Endoplasmic Reticulum, Mitochondria, and Lysosomes. Trends Biochem Sci 2016; 41:1035-1049. [PMID: 27692849 DOI: 10.1016/j.tibs.2016.09.001] [Citation(s) in RCA: 345] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/31/2016] [Accepted: 09/07/2016] [Indexed: 12/29/2022]
Abstract
In recent years, rapid discoveries have been made relating to Ca2+ handling at specific organelles that have important implications for whole-cell Ca2+ homeostasis. In particular, the structures of the endoplasmic reticulum (ER) Ca2+ channels revealed by electron cryomicroscopy (cryo-EM), continuous updates on the structure, regulation, and role of the mitochondrial calcium uniporter (MCU) complex, and the analysis of lysosomal Ca2+ signaling are milestones on the route towards a deeper comprehension of the complexity of global Ca2+ signaling. In this review we summarize recent discoveries on the regulation of interorganellar Ca2+ homeostasis and its role in pathophysiology.
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Affiliation(s)
- Anna Raffaello
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.
| | - Cristina Mammucari
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.
| | - Gaia Gherardi
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy; Neuroscience Institute, National Research Council, 35131 Padua, Italy.
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76
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Leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) forms a Ca 2+/H + antiporter. Sci Rep 2016; 6:34174. [PMID: 27669901 PMCID: PMC5037442 DOI: 10.1038/srep34174] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/08/2016] [Indexed: 02/06/2023] Open
Abstract
Leucine zipper-EF-hand-containing transmembrane protein1 (LETM1) is located in the mitochondrial inner membrane and is defective in Wolf-Hirschhorn syndrome. LETM1 contains only one transmembrane helix, but it behaves as a putative transporter. Our data shows that LETM1 knockdown or overexpression robustly increases or decreases mitochondrial Ca2+ level in HeLa cells, respectively. Also the residue Glu221 of mouse LETM1 is identified to be necessary for Ca2+ flux. The mutation of Glu221 to glutamine abolishes the Ca2+-transport activity of LETM1 in cells. Furthermore, the purified LETM1 exhibits Ca2+/H+ anti-transport activity, and the activity is enhanced as the proton gradient is increased. More importantly, electron microscopy studies reveal a hexameric LETM1 with a central cavity, and also, observe two different conformational states under alkaline and acidic conditions, respectively. Our results indicate that LETM1 is a Ca2+/H+ antiporter and most likely responsible for mitochondrial Ca2+ output.
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77
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Madreiter-Sokolowski CT, Klec C, Parichatikanond W, Stryeck S, Gottschalk B, Pulido S, Rost R, Eroglu E, Hofmann NA, Bondarenko AI, Madl T, Waldeck-Weiermair M, Malli R, Graier WF. PRMT1-mediated methylation of MICU1 determines the UCP2/3 dependency of mitochondrial Ca(2+) uptake in immortalized cells. Nat Commun 2016; 7:12897. [PMID: 27642082 PMCID: PMC5031806 DOI: 10.1038/ncomms12897] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 08/12/2016] [Indexed: 12/18/2022] Open
Abstract
Recent studies revealed that mitochondrial Ca2+ channels, which control energy flow, cell signalling and death, are macromolecular complexes that basically consist of the pore-forming mitochondrial Ca2+ uniporter (MCU) protein, the essential MCU regulator (EMRE), and the mitochondrial Ca2+ uptake 1 (MICU1). MICU1 is a regulatory subunit that shields mitochondria from Ca2+ overload. Before the identification of these core elements, the novel uncoupling proteins 2 and 3 (UCP2/3) have been shown to be fundamental for mitochondrial Ca2+ uptake. Here we clarify the molecular mechanism that determines the UCP2/3 dependency of mitochondrial Ca2+ uptake. Our data demonstrate that mitochondrial Ca2+ uptake is controlled by protein arginine methyl transferase 1 (PRMT1) that asymmetrically methylates MICU1, resulting in decreased Ca2+ sensitivity. UCP2/3 normalize Ca2+ sensitivity of methylated MICU1 and, thus, re-establish mitochondrial Ca2+ uptake activity. These data provide novel insights in the complex regulation of the mitochondrial Ca2+ uniporter by PRMT1 and UCP2/3. MICU1 is a regulatory subunit of mitochondrial Ca2+ channels that shields mitochondria from Ca2+ overload. Here the authors show that MICU1 methylation by PRMT1 reduces Ca2+ sensitivity, which is normalized by UCP2/3, re-establishing mitochondrial Ca2+ uptake activity.
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Affiliation(s)
- Corina T Madreiter-Sokolowski
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Christiane Klec
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Warisara Parichatikanond
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Sarah Stryeck
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Benjamin Gottschalk
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Sergio Pulido
- Institute of Chemistry, University of Graz, Graz 8010, Austria
| | - Rene Rost
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Emrah Eroglu
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Nicole A Hofmann
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Alexander I Bondarenko
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Tobias Madl
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria.,Center for Integrated Protein Science, Department Chemistry, Technical University Munich, Garching 85748, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg 85764, Germany
| | - Markus Waldeck-Weiermair
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Roland Malli
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
| | - Wolfgang F Graier
- Center for Molecular Medicine, Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/III, Graz 8010, Austria
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78
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Madreiter-Sokolowski CT, Gottschalk B, Parichatikanond W, Eroglu E, Klec C, Waldeck-Weiermair M, Malli R, Graier WF. Resveratrol Specifically Kills Cancer Cells by a Devastating Increase in the Ca2+ Coupling Between the Greatly Tethered Endoplasmic Reticulum and Mitochondria. Cell Physiol Biochem 2016; 39:1404-20. [PMID: 27606689 PMCID: PMC5382978 DOI: 10.1159/000447844] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2016] [Indexed: 12/31/2022] Open
Abstract
Background/Aims Resveratrol and its derivate piceatannol are known to induce cancer cell-specific cell death. While multiple mechanisms of actions have been described including the inhibition of ATP synthase, changes in mitochondrial membrane potential and ROS levels, the exact mechanisms of cancer specificity of these polyphenols remain unclear. This paper is designed to reveal the molecular basis of the cancer-specific initiation of cell death by resveratrol and piceatannol. Methods The two cancer cell lines EA.hy926 and HeLa, and somatic short-term cultured HUVEC were used. Cell viability and caspase 3/7 activity were tested. Mitochondrial, cytosolic and endoplasmic reticulum Ca2+ as well as cytosolic and mitochondrial ATP levels were measured using single cell fluorescence microscopy and respective genetically-encoded sensors. Mitochondria-ER junctions were analyzed applying super-resolution SIM and ImageJ-based image analysis. Results Resveratrol and piceatannol selectively trigger death in cancer but not somatic cells. Hence, these polyphenols strongly enhanced mitochondrial Ca2+ uptake in cancer exclusively. Resveratrol and piceatannol predominantly affect mitochondrial but not cytosolic ATP content that yields in a reduced SERCA activity. Decreased SERCA activity and the strongly enriched tethering of the ER and mitochondria in cancer cells result in an enhanced MCU/Letm1-dependent mitochondrial Ca2+ uptake upon intracellular Ca2+ release exclusively in cancer cells. Accordingly, resveratrol/piceatannol-induced cancer cell death could be prevented by siRNA-mediated knock-down of MCU and Letm1. Conclusions Because their greatly enriched ER-mitochondria tethering, cancer cells are highly susceptible for resveratrol/piceatannol-induced reduction of SERCA activity to yield mitochondrial Ca2+ overload and subsequent cancer cell death.
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79
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Zhu MX, Tuo B, Yang JJ. The hills and valleys of calcium signaling. SCIENCE CHINA-LIFE SCIENCES 2016; 59:743-8. [DOI: 10.1007/s11427-016-5098-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Indexed: 10/21/2022]
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80
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Li D, Wu W, Pei H, Wei Q, Yang Q, Zheng J, Jia Z. Expression and preliminary characterization of human MICU2. Biol Open 2016; 5:962-9. [PMID: 27334695 PMCID: PMC4958273 DOI: 10.1242/bio.018572] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/31/2016] [Indexed: 01/04/2023] Open
Abstract
MICU2 has been reported to interact with MICU1 and participate in the regulation of mitochondrial Ca(2+) uptake, although the molecular determinants underlying the function of MICU2 is unknown. In order to characterize MICU2 we screened a series of N-terminal and C-terminal truncations and obtained constructs which can be expressed in abundance, giving rise to soluble samples to enable subsequent characterizations. Size exclusion chromatography (SEC) and multi-angle laser light scattering (MALLS) revealed that MICU2 exists as a monomer in Ca(2+)-free conditions but forms a dimer in Ca(2+)-bound conditions. Unlike MICU1, the C-helix domain of MICU2 exhibits no influence on protein conformation in both Ca(2+)-free and Ca(2+)-bound forms. Furthermore, mutation of the first EF-hand abolishes the ability of MICU2 to switch to a dimer in the presence of Ca(2+), indicating that the first EF-hand is not only involved in Ca(2+) binding but also in conformational change. Our pull-down and co-immunoprecipitation assays suggest that, in addition to disulfide bonds, salt bridges also contribute to MICU1-MICU2 heterodimer formation.
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Affiliation(s)
- Dan Li
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wenping Wu
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Hairun Pei
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Qiang Wei
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Qingzhan Yang
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jimin Zheng
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Zongchao Jia
- Department of Biochemical and Molecular Science, Queen University, Kingston, Ontario, Canada K7L 3N6
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81
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Wagner S, De Bortoli S, Schwarzländer M, Szabò I. Regulation of mitochondrial calcium in plants versus animals. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3809-29. [PMID: 27001920 DOI: 10.1093/jxb/erw100] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ca(2+) acts as an important cellular second messenger in eukaryotes. In both plants and animals, a wide variety of environmental and developmental stimuli trigger Ca(2+) transients of a specific signature that can modulate gene expression and metabolism. In animals, mitochondrial energy metabolism has long been considered a hotspot of Ca(2+) regulation, with a range of pathophysiology linked to altered Ca(2+) control. Recently, several molecular players involved in mitochondrial Ca(2+) signalling have been identified, including those of the mitochondrial Ca(2+) uniporter. Despite strong evidence for sophisticated Ca(2+) regulation in plant mitochondria, the picture has remained much less clear. This is currently changing aided by live imaging and genetic approaches which allow dissection of subcellular Ca(2+) dynamics and identification of the proteins involved. We provide an update on our current understanding in the regulation of mitochondrial Ca(2+) and signalling by comparing work in plants and animals. The significance of mitochondrial Ca(2+) control is discussed in the light of the specific metabolic and energetic needs of plant and animal cells.
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Affiliation(s)
- Stephan Wagner
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
| | - Sara De Bortoli
- Department of Biology and CNR Institute of Neurosciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Markus Schwarzländer
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
| | - Ildikò Szabò
- Department of Biology and CNR Institute of Neurosciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
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82
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Abstract
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Affiliation(s)
- Diego De Stefani
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , ,
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy.,Venetian Institute of Molecular Medicine, 35121 Padova, Italy
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83
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Jhun BS, Mishra J, Monaco S, Fu D, Jiang W, Sheu SS, O-Uchi J. The mitochondrial Ca2+ uniporter: regulation by auxiliary subunits and signal transduction pathways. Am J Physiol Cell Physiol 2016; 311:C67-80. [PMID: 27122161 DOI: 10.1152/ajpcell.00319.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Mitochondrial Ca(2+) homeostasis, the Ca(2+) influx-efflux balance, is responsible for the control of numerous cellular functions, including energy metabolism, generation of reactive oxygen species, spatiotemporal dynamics of Ca(2+) signaling, and cell growth and death. Recent discovery of the molecular identity of the mitochondrial Ca(2+) uniporter (MCU) provides new possibilities for application of genetic approaches to study the mitochondrial Ca(2+) influx mechanism in various cell types and tissues. In addition, the subsequent discovery of various auxiliary subunits associated with MCU suggests that mitochondrial Ca(2+) uptake is not solely regulated by a single protein (MCU), but likely by a macromolecular protein complex, referred to as the MCU-protein complex (mtCUC). Moreover, recent reports have shown the potential role of MCU posttranslational modifications in the regulation of mitochondrial Ca(2+) uptake through mtCUC. These observations indicate that mtCUCs form a local signaling complex at the inner mitochondrial membrane that could significantly regulate mitochondrial Ca(2+) handling, as well as numerous mitochondrial and cellular functions. In this review we discuss the current literature on mitochondrial Ca(2+) uptake mechanisms, with a particular focus on the structure and function of mtCUC, as well as its regulation by signal transduction pathways, highlighting current controversies and discrepancies.
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Affiliation(s)
- Bong Sook Jhun
- Cardiovascular Research Center, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - Jyotsna Mishra
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Sarah Monaco
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Deming Fu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Wenmin Jiang
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jin O-Uchi
- Cardiovascular Research Center, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island; and
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84
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Antony AN, Paillard M, Moffat C, Juskeviciute E, Correnti J, Bolon B, Rubin E, Csordás G, Seifert EL, Hoek JB, Hajnóczky G. MICU1 regulation of mitochondrial Ca(2+) uptake dictates survival and tissue regeneration. Nat Commun 2016; 7:10955. [PMID: 26956930 PMCID: PMC4786880 DOI: 10.1038/ncomms10955] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 02/03/2016] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial Ca2+ uptake through the recently discovered Mitochondrial Calcium Uniporter (MCU) is controlled by its gatekeeper Mitochondrial Calcium Uptake 1 (MICU1). However, the physiological and pathological role of MICU1 remains unclear. Here we show that MICU1 is vital for adaptation to postnatal life and for tissue repair after injury. MICU1 knockout is perinatally lethal in mice without causing gross anatomical defects. We used liver regeneration after partial hepatectomy as a physiological stress response model. Upon MICU1 loss, early priming is unaffected, but the pro-inflammatory phase does not resolve and liver regeneration fails, with impaired cell cycle entry and extensive necrosis. Ca2+ overload-induced mitochondrial permeability transition pore (PTP) opening is accelerated in MICU1-deficient hepatocytes. PTP inhibition prevents necrosis and rescues regeneration. Thus, our study identifies an unanticipated dependence of liver regeneration on MICU1 and highlights the importance of regulating MCU under stress conditions when the risk of Ca2+ overload is elevated. Mitochondrial calcium uptake is a highly regulated process, and calcium overload can lead to cell death. Here, using knockout mouse model, the authors show that the mitochondrial calcium uniporter (MCU) regulator MICU1 is needed to prevent calcium overload and promotes survival under liver regeneration and postnatal adaptation-associated stress.
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Affiliation(s)
- Anil Noronha Antony
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Cynthia Moffat
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Egle Juskeviciute
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jason Correnti
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Brad Bolon
- Comparative Pathology and Mouse Phenotyping Shared Resource, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210, USA
| | - Emanuel Rubin
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Erin L Seifert
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jan B Hoek
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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85
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Terwilliger TC, Bunkóczi G, Hung LW, Zwart PH, Smith JL, Akey DL, Adams PD. Can I solve my structure by SAD phasing? Anomalous signal in SAD phasing. Acta Crystallogr D Struct Biol 2016; 72:346-58. [PMID: 26960122 PMCID: PMC4784666 DOI: 10.1107/s2059798315019269] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 10/12/2015] [Indexed: 12/19/2022] Open
Abstract
A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. A simple theoretical framework for describing measurements of anomalous differences and the resulting useful anomalous correlation and anomalous signal in a SAD experiment is presented. Here, the useful anomalous correlation is defined as the correlation of anomalous differences with ideal anomalous differences from the anomalous substructure. The useful anomalous correlation reflects the accuracy of the data and the absence of minor sites. The useful anomalous correlation also reflects the information available for estimating crystallographic phases once the substructure has been determined. In contrast, the anomalous signal (the peak height in a model-phased anomalous difference Fourier at the coordinates of atoms in the anomalous substructure) reflects the information available about each site in the substructure and is related to the ability to find the substructure. A theoretical analysis shows that the expected value of the anomalous signal is the product of the useful anomalous correlation, the square root of the ratio of the number of unique reflections in the data set to the number of sites in the substructure, and a function that decreases with increasing values of the atomic displacement factor for the atoms in the substructure. This means that the ability to find the substructure in a SAD experiment is increased by high data quality and by a high ratio of reflections to sites in the substructure, and is decreased by high atomic displacement factors for the substructure.
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Affiliation(s)
- Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Mail Stop M888, Los Alamos, NM 87545, USA
| | - Gábor Bunkóczi
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge CB2 0XY, England
| | - Li-Wei Hung
- Physics Division, Los Alamos National Laboratory, Mail Stop D454, Los Alamos, NM 87545, USA
| | - Peter H. Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Janet L. Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - David L. Akey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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86
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Terwilliger TC, Bunkóczi G, Hung LW, Zwart PH, Smith JL, Akey DL, Adams PD. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal. Acta Crystallogr D Struct Biol 2016; 72:359-74. [PMID: 26960123 PMCID: PMC4784667 DOI: 10.1107/s2059798315019403] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 10/13/2015] [Indexed: 01/15/2023] Open
Abstract
A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment are described. A simple theoretical framework [Terwilliger et al. (2016), Acta Cryst. D72, 346-358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. The phenix.plan_sad_experiment tool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimate the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. The phenix.scale_and_merge tool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and the phenix.anomalous_signal tool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing.
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Affiliation(s)
- Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Mail Stop M888, Los Alamos, NM 87545, USA
| | - Gábor Bunkóczi
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge CB2 0XY, England
| | - Li-Wei Hung
- Physics Division, Los Alamos National Laboratory, Mail Stop D454, Los Alamos, NM 87545, USA
| | - Peter H. Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Janet L. Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - David L. Akey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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87
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The Roles of Mitochondrial Cation Channels Under Physiological Conditions and in Cancer. Handb Exp Pharmacol 2016; 240:47-69. [PMID: 27995386 DOI: 10.1007/164_2016_92] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bioenergetics has become central to our understanding of pathological mechanisms as well as the development of new therapeutic strategies and as a tool for gauging disease progression in neurodegeneration, diabetes, cancer, and cardiovascular disease. The view is emerging that inner mitochondrial membrane (IMM) cation channels have a profound effect on mitochondrial function and, consequently, on the metabolic state and survival of the whole cell. Since disruption of the sustained integrity of mitochondria is strongly linked to human disease, pharmacological intervention offers a new perspective concerning neurodegenerative and cardiovascular diseases as well as cancer. This review summarizes our current knowledge regarding IMM cation channels and their roles under physiological conditions as well as in cancer, with special emphasis on potassium channels and the mammalian mitochondrial calcium uniporter.
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88
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Santo-Domingo J, Wiederkehr A, De Marchi U. Modulation of the matrix redox signaling by mitochondrial Ca 2+. World J Biol Chem 2015; 6:310-323. [PMID: 26629314 PMCID: PMC4657127 DOI: 10.4331/wjbc.v6.i4.310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/04/2015] [Accepted: 10/13/2015] [Indexed: 02/05/2023] Open
Abstract
Mitochondria sense, shape and integrate signals, and thus function as central players in cellular signal transduction. Ca2+ waves and redox reactions are two such intracellular signals modulated by mitochondria. Mitochondrial Ca2+ transport is of utmost physio-pathological relevance with a strong impact on metabolism and cell fate. Despite its importance, the molecular nature of the proteins involved in mitochondrial Ca2+ transport has been revealed only recently. Mitochondrial Ca2+ promotes energy metabolism through the activation of matrix dehydrogenases and down-stream stimulation of the respiratory chain. These changes also alter the mitochondrial NAD(P)H/NAD(P)+ ratio, but at the same time will increase reactive oxygen species (ROS) production. Reducing equivalents and ROS are having opposite effects on the mitochondrial redox state, which are hard to dissect. With the recent development of genetically encoded mitochondrial-targeted redox-sensitive sensors, real-time monitoring of matrix thiol redox dynamics has become possible. The discoveries of the molecular nature of mitochondrial transporters of Ca2+ combined with the utilization of the novel redox sensors is shedding light on the complex relation between mitochondrial Ca2+ and redox signals and their impact on cell function. In this review, we describe mitochondrial Ca2+ handling, focusing on a number of newly identified proteins involved in mitochondrial Ca2+ uptake and release. We further discuss our recent findings, revealing how mitochondrial Ca2+ influences the matrix redox state. As a result, mitochondrial Ca2+ is able to modulate the many mitochondrial redox-regulated processes linked to normal physiology and disease.
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89
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Wagner S, Behera S, De Bortoli S, Logan DC, Fuchs P, Carraretto L, Teardo E, Cendron L, Nietzel T, Füßl M, Doccula FG, Navazio L, Fricker MD, Van Aken O, Finkemeier I, Meyer AJ, Szabò I, Costa A, Schwarzländer M. The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis. THE PLANT CELL 2015; 27:3190-212. [PMID: 26530087 PMCID: PMC4682298 DOI: 10.1105/tpc.15.00509] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/25/2015] [Accepted: 10/15/2015] [Indexed: 05/18/2023]
Abstract
Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca(2+) signaling may play a central role in this process. Free Ca(2+) dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca(2+) dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca(2+) uniporter machinery in mammals. MICU binds Ca(2+) and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca(2+) sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca(2+) in the matrix. Furthermore, Ca(2+) elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca(2+) signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca(2+) uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca(2+) uptake by moderating influx, thereby shaping Ca(2+) signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca(2+) signaling in plants.
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Affiliation(s)
- Stephan Wagner
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | | | - Sara De Bortoli
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - David C Logan
- Université d'Angers, INRA, Agrocampus Ouest, UMR 1345 Institut de Recherche en Horticulture et Semences, F-49045 Angers, France
| | - Philippe Fuchs
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | - Luca Carraretto
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - Laura Cendron
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - Thomas Nietzel
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | - Magdalena Füßl
- Plant Proteomics Group, Max-Planck-Institute for Plant Breeding Research, 50829 Cologne, Germany
| | | | - Lorella Navazio
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - Mark D Fricker
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Olivier Van Aken
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, WA 6009, Australia
| | - Iris Finkemeier
- Plant Proteomics Group, Max-Planck-Institute for Plant Breeding Research, 50829 Cologne, Germany Institute for Plant Biology and Biotechnology, University of Münster, 48149 Münster, Germany
| | - Andreas J Meyer
- Department Chemical Signalling, Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
| | - Ildikò Szabò
- Department of Biology, University of Padova, 35121 Padova, Italy
| | - Alex Costa
- Department of Biosciences, University of Milan, 20133 Milan, Italy Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy
| | - Markus Schwarzländer
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation, University of Bonn, 53113 Bonn, Germany
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90
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Rearrangement of MICU1 multimers for activation of MCU is solely controlled by cytosolic Ca(2.). Sci Rep 2015; 5:15602. [PMID: 26489515 PMCID: PMC4615007 DOI: 10.1038/srep15602] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 09/07/2015] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial Ca2+ uptake is a vital process that controls distinct cell and organelle functions. Mitochondrial calcium uptake 1 (MICU1) was identified as key regulator of the mitochondrial Ca2+ uniporter (MCU) that together with the essential MCU regulator (EMRE) forms the mitochondrial Ca2+ channel. However, mechanisms by which MICU1 controls MCU/EMRE activity to tune mitochondrial Ca2+ signals remain ambiguous. Here we established a live-cell FRET approach and demonstrate that elevations of cytosolic Ca2+ rearranges MICU1 multimers with an EC50 of 4.4 μM, resulting in activation of mitochondrial Ca2+ uptake. MICU1 rearrangement essentially requires the EF-hand motifs and strictly correlates with the shape of cytosolic Ca2+ rises. We further show that rearrangements of MICU1 multimers were independent of matrix Ca2+ concentration, mitochondrial membrane potential, and expression levels of MCU and EMRE. Our experiments provide novel details about how MCU/EMRE is regulated by MICU1 and an original approach to investigate MCU/EMRE activation in intact cells.
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91
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Abstract
The mitochondrial calcium uniporter is an evolutionarily conserved calcium channel, and its biophysical properties and relevance to cell death, bioenergetics and signalling have been investigated for decades. However, the genes encoding this channel have only recently been discovered, opening up a new 'molecular era' in the study of its biology. We now know that the uniporter is not a single protein but rather a macromolecular complex consisting of pore-forming and regulatory subunits. We review recent studies that harnessed the power of molecular biology and genetics to characterize the mechanism of action of the uniporter, its evolution and its contribution to physiology and human disease.
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92
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UCP2 modulates single-channel properties of a MCU-dependent Ca(2+) inward current in mitochondria. Pflugers Arch 2015; 467:2509-18. [PMID: 26275882 PMCID: PMC4646917 DOI: 10.1007/s00424-015-1727-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 01/14/2023]
Abstract
The mitochondrial Ca(2+) uniporter is a highly Ca(2+)-selective protein complex that consists of the pore-forming mitochondrial Ca(2+) uniporter protein (MCU), the scaffolding essential MCU regulator (EMRE), and mitochondrial calcium uptake 1 and 2 (MICU1/2), which negatively regulate mitochondrial Ca(2+) uptake. We have previously reported that uncoupling proteins 2 and 3 (UCP2/3) are also engaged in the activity of mitochondrial Ca(2+) uptake under certain conditions, while the mechanism by which UCP2/3 facilitates mitochondrial Ca(2+) uniport remains elusive. This work was designed to investigate the impact of UCP2 on the three distinct mitochondrial Ca(2+) currents found in mitoplasts isolated from HeLa cells, the intermediate- (i-), burst- (b-) and extra-large (xl-) mitochondrial/mitoplast Ca(2+) currents (MCC). Using the patch clamp technique on mitoplasts from cells with reduced MCU and EMRE unveiled a very high affinity of MCU for xl-MCC that succeeds that for i-MCC, indicating the coexistence of at least two MCU/EMRE-dependent Ca(2+) currents. The manipulation of the expression level of UCP2 by either siRNA-mediated knockdown or overexpression changed exclusively the open probability (NPo) of xl-MCC by approx. 38% decrease or nearly a 3-fold increase, respectively. These findings confirm a regulatory role of UCP2 in mitochondrial Ca(2+) uptake and identify UCP2 as a selective modulator of just one distinct MCU/EMRE-dependent mitochondrial Ca(2+) inward current.
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93
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Finkel T, Menazza S, Holmström KM, Parks RJ, Liu J, Sun J, Liu J, Pan X, Murphy E. The ins and outs of mitochondrial calcium. Circ Res 2015; 116:1810-9. [PMID: 25999421 DOI: 10.1161/circresaha.116.305484] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Calcium is thought to play an important role in regulating mitochondrial function. Evidence suggests that an increase in mitochondrial calcium can augment ATP production by altering the activity of calcium-sensitive mitochondrial matrix enzymes. In contrast, the entry of large amounts of mitochondrial calcium in the setting of ischemia-reperfusion injury is thought to be a critical event in triggering cellular necrosis. For many decades, the details of how calcium entered the mitochondria remained a biological mystery. In the past few years, significant progress has been made in identifying the molecular components of the mitochondrial calcium uniporter complex. Here, we review how calcium enters and leaves the mitochondria, the growing insight into the topology, stoichiometry and function of the uniporter complex, and the early lessons learned from some initial mouse models that genetically perturb mitochondrial calcium homeostasis.
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Affiliation(s)
- Toren Finkel
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.).
| | - Sara Menazza
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Kira M Holmström
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Randi J Parks
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Julia Liu
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Junhui Sun
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Jie Liu
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Xin Pan
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.)
| | - Elizabeth Murphy
- From the Center for Molecular Medicine (T.F., K.M.H., Julia Liu, Jie Liu) and Systems Biology Center (S.M., R.J.P., J.S., E.M.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing, China (X.P.).
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94
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Arnold P, Schmidt F, Prox J, Zunke F, Pietrzik C, Lucius R, Becker-Pauly C. Calcium negatively regulates meprin β activity and attenuates substrate cleavage. FASEB J 2015; 29:3549-57. [DOI: 10.1096/fj.15-272310] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/27/2015] [Indexed: 12/31/2022]
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95
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Wang L, Yang X, Shen Y. Molecular mechanism of mitochondrial calcium uptake. Cell Mol Life Sci 2015; 72:1489-98. [PMID: 25548802 PMCID: PMC11113575 DOI: 10.1007/s00018-014-1810-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 12/15/2014] [Accepted: 12/18/2014] [Indexed: 12/21/2022]
Abstract
Mitochondrial calcium uptake plays a critical role in various cellular functions. After half a century of extensive studies, the molecular components and important regulators of the mitochondrial calcium uptake complex have been identified. However, the mechanism by which these protein molecules interact with one another and coordinate to regulate calcium passage through mitochondrial membranes remains elusive. Here, we summarize recent progress in the structural and functional characterization of these important protein molecules, which are involved in mitochondrial calcium uptake. In particular, we focus on the current understanding of the molecular mechanism underlying calcium through two mitochondrial membranes. Additionally, we provide a new perspective for future directions in investigation and molecular intervention.
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Affiliation(s)
- Lele Wang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Xue Yang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin, 300071 China
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071 China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072 China
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96
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The mitochondrial Ca(2+) uniporter complex. J Mol Cell Cardiol 2014; 78:3-8. [PMID: 25463276 DOI: 10.1016/j.yjmcc.2014.11.015] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 01/09/2023]
Abstract
Calcium influx into the mitochondrial matrix plays important roles in the regulation of cell death pathways, bioenergetics and cytoplasmic Ca(2+) signals. During the last few years, several molecular components of the inner membrane mitochondrial Ca(2+) uniporter, the dominant pathway for Ca(2+) influx into the mitochondrial matrix, have been identified. The uniporter is now recognized as a complex of proteins that include a Ca(2+) pore forming component and accessory proteins that are either required for its channel activity or regulate it under various conditions. This review summarizes recent discoveries about the molecular basis of the uniporter complex. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease."
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97
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Docampo R, Vercesi AE, Huang G. Mitochondrial calcium transport in trypanosomes. Mol Biochem Parasitol 2014; 196:108-16. [PMID: 25218432 DOI: 10.1016/j.molbiopara.2014.09.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/22/2014] [Accepted: 09/02/2014] [Indexed: 01/26/2023]
Abstract
The biochemical peculiarities of trypanosomes were fundamental for the recent molecular identification of the long-sought channel involved in mitochondrial Ca(2+) uptake, the mitochondrial Ca(2+) uniporter or MCU. This discovery led to the finding of numerous regulators of the channel, which form a high molecular weight complex with MCU. Some of these regulators have been bioinformatically identified in trypanosomes, which are the first eukaryotic organisms described for which MCU is essential. In trypanosomes MCU is important for buffering cytosolic Ca(2+) changes and for activation of the bioenergetics of the cells. Future work on this pathway in trypanosomes promises further insight into the biology of these fascinating eukaryotes, as well as the potential for novel target discovery.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; Departamento de Patologia Clínica, State University of Campinas, Campinas 13083, SP, Brazil.
| | - Anibal E Vercesi
- Departamento de Patologia Clínica, State University of Campinas, Campinas 13083, SP, Brazil
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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98
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Hajnóczky G, Booth D, Csordás G, Debattisti V, Golenár T, Naghdi S, Niknejad N, Paillard M, Seifert EL, Weaver D. Reliance of ER-mitochondrial calcium signaling on mitochondrial EF-hand Ca2+ binding proteins: Miros, MICUs, LETM1 and solute carriers. Curr Opin Cell Biol 2014; 29:133-41. [PMID: 24999559 PMCID: PMC4381426 DOI: 10.1016/j.ceb.2014.06.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/09/2014] [Accepted: 06/11/2014] [Indexed: 10/25/2022]
Abstract
Endoplasmic reticulum (ER) and mitochondria are functionally distinct with regard to membrane protein biogenesis and oxidative energy production, respectively, but cooperate in several essential cell functions, including lipid biosynthesis, cell signaling and organelle dynamics. The interorganellar cooperation requires local communication that can occur at the strategically positioned and dynamic associations between ER and mitochondria. Calcium is locally transferred from ER to mitochondria at the associations and exerts regulatory effects on numerous proteins. A common Ca(2+) sensing mechanism is the EF-hand Ca(2+) binding domain, many of which can be found in proteins of the mitochondria, including Miro1&2, MICU1,2&3, LETM1 and mitochondrial solute carriers. Recently, these proteins have triggered much interest and were described in reports with diverging conclusions. The present essay focuses on their shared features and established specific functions.
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Affiliation(s)
- György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States.
| | - David Booth
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Valentina Debattisti
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Tünde Golenár
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Shamim Naghdi
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Nima Niknejad
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Erin L Seifert
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - David Weaver
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
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100
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Gu J, Feng Y, Feng X, Sun C, Lei L, Ding W, Niu F, Jiao L, Yang M, Li Y, Liu X, Song J, Cui Z, Han D, Du C, Yang Y, Ouyang S, Liu ZJ, Han W. Structural and biochemical characterization reveals LysGH15 as an unprecedented "EF-hand-like" calcium-binding phage lysin. PLoS Pathog 2014; 10:e1004109. [PMID: 24831957 PMCID: PMC4022735 DOI: 10.1371/journal.ppat.1004109] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/25/2014] [Indexed: 11/18/2022] Open
Abstract
The lysin LysGH15, which is derived from the staphylococcal phage GH15, demonstrates a wide lytic spectrum and strong lytic activity against methicillin-resistant Staphylococcus aureus (MRSA). Here, we find that the lytic activity of the full-length LysGH15 and its CHAP domain is dependent on calcium ions. To elucidate the molecular mechanism, the structures of three individual domains of LysGH15 were determined. Unexpectedly, the crystal structure of the LysGH15 CHAP domain reveals an "EF-hand-like" calcium-binding site near the Cys-His-Glu-Asn quartet active site groove. To date, the calcium-binding site in the LysGH15 CHAP domain is unique among homologous proteins, and it represents the first reported calcium-binding site in the CHAP family. More importantly, the calcium ion plays an important role as a switch that modulates the CHAP domain between the active and inactive states. Structure-guided mutagenesis of the amidase-2 domain reveals that both the zinc ion and E282 are required in catalysis and enable us to propose a catalytic mechanism. Nuclear magnetic resonance (NMR) spectroscopy and titration-guided mutagenesis identify residues (e.g., N404, Y406, G407, and T408) in the SH3b domain that are involved in the interactions with the substrate. To the best of our knowledge, our results constitute the first structural information on the biochemical features of a staphylococcal phage lysin and represent a pivotal step forward in understanding this type of lysin.
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Affiliation(s)
- Jingmin Gu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yingang Feng
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Xin Feng
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Changjiang Sun
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Liancheng Lei
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Wei Ding
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Fengfeng Niu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Lianying Jiao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Mei Yang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yue Li
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xiaohe Liu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jun Song
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Ziyin Cui
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Dong Han
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Chongtao Du
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yongjun Yang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Songying Ouyang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Zhi-Jie Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wenyu Han
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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