1
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Taha M, Assali EA, Ben-Kasus Nissim T, Stutzmann GE, Shirihai OS, Hershfinkel M, Sekler I. NCLX controls hepatic mitochondrial Ca 2+ extrusion and couples hormone-mediated mitochondrial Ca 2+ oscillations with gluconeogenesis. Mol Metab 2024; 87:101982. [PMID: 38960129 PMCID: PMC11325370 DOI: 10.1016/j.molmet.2024.101982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/05/2024] Open
Abstract
OBJECTIVE Hepatic Ca2+ signaling has been identified as a crucial key factor in driving gluconeogenesis. The involvement of mitochondria in hormone-induced Ca2+ signaling and their contribution to metabolic activity remain, however, poorly understood. Moreover, the molecular mechanism governing the mitochondrial Ca2+ efflux signaling remains unresolved. This study investigates the role of the Na+/Ca2+ exchanger, NCLX, in modulating hepatic mitochondrial Ca2+ efflux, and examines its physiological significance in hormonal hepatic Ca2+ signaling, gluconeogenesis, and mitochondrial bioenergetics. METHODS Primary mouse hepatocytes from both an AAV-mediated conditional hepatic-specific and a total mitochondrial Na+/Ca2+ exchanger, NCLX, knockout (KO) mouse models were employed for fluorescent monitoring of purinergic and glucagon/vasopressin-dependent mitochondrial and cytosolic hepatic Ca2+ responses in cultured hepatocytes. Isolated liver mitochondria and permeabilized primary hepatocytes were used to analyze the ion-dependence of Ca2+ efflux. Utilizing the conditional hepatic-specific NCLX KO model, the rate of gluconeogenesis was assessed by first monitoring glucose levels in fasted mice, and subsequently subjecting the mice to a pyruvate tolerance test while monitoring their blood glucose. Additionally, cultured primary hepatocytes from both genotypes were assessed in vitro for glucagon-dependent glucose production and cellular bioenergetics through glucose oxidase assay and Seahorse respirometry, respectively. RESULTS Analysis of Ca2+ responses in isolated liver mitochondria and cultured primary hepatocytes from NCLX KO versus WT mice showed that NCLX serves as the principal mechanism for mitochondrial calcium extrusion in hepatocytes. We then determined the role of NCLX in glucagon and vasopressin-induced Ca2+ oscillations. Consistent with previous studies, glucagon and vasopressin triggered Ca2+ oscillations in WT hepatocytes, however, the deletion of NCLX resulted in selective elimination of mitochondrial, but not cytosolic, Ca2+ oscillations, underscoring NCLX's pivotal role in mitochondrial Ca2+ regulation. Subsequent in vivo investigation for hepatic NCLX role in gluconeogenesis revealed that, as opposed to WT mice which maintained normoglycemic blood glucose levels when fasted, conditional hepatic-specific NCLX KO mice exhibited a faster drop in glucose levels, becoming hypoglycemic. Furthermore, KO mice showed deficient conversion of pyruvate to glucose when challenged under fasting conditions. Concurrent in vitro assessments showed impaired glucagon-dependent glucose production and compromised bioenergetics in KO hepatocytes, thereby underscoring NCLX's significant contribution to hepatic glucose metabolism. CONCLUSIONS The study findings demonstrate that NCLX acts as the primary Ca2+ efflux mechanism in hepatocytes. NCLX is indispensable for regulating hormone-induced mitochondrial Ca2+ oscillations, mitochondrial metabolism, and sustenance of hepatic gluconeogenesis.
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Affiliation(s)
- Mahmoud Taha
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Essam A Assali
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel; Department of Medicine, Endocrinology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA; Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA.
| | - Tsipi Ben-Kasus Nissim
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Grace E Stutzmann
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University of Medicine and Science. North Chicago, IL 60064, USA
| | - Orian S Shirihai
- Department of Medicine, Endocrinology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA; Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA; Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel.
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2
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Vecellio Reane D, Serna JDC, Raffaello A. Unravelling the complexity of the mitochondrial Ca 2+ uniporter: regulation, tissue specificity, and physiological implications. Cell Calcium 2024; 121:102907. [PMID: 38788256 DOI: 10.1016/j.ceca.2024.102907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024]
Abstract
Calcium (Ca2+) signalling acts a pleiotropic message within the cell that is decoded by the mitochondria through a sophisticated ion channel known as the Mitochondrial Ca2+ Uniporter (MCU) complex. Under physiological conditions, mitochondrial Ca2+ signalling is crucial for coordinating cell activation with energy production. Conversely, in pathological scenarios, it can determine the fine balance between cell survival and death. Over the last decade, significant progress has been made in understanding the molecular bases of mitochondrial Ca2+ signalling. This began with the elucidation of the MCU channel components and extended to the elucidation of the mechanisms that regulate its activity. Additionally, increasing evidence suggests molecular mechanisms allowing tissue-specific modulation of the MCU complex, tailoring channel activity to the specific needs of different tissues or cell types. This review aims to explore the latest evidence elucidating the regulation of the MCU complex, the molecular factors controlling the tissue-specific properties of the channel, and the physiological and pathological implications of mitochondrial Ca2+ signalling in different tissues.
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Affiliation(s)
- Denis Vecellio Reane
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum Munich, Germany.
| | - Julian D C Serna
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padova, Italy.
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3
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Ge WD, Du TT, Wang CY, Sun LN, Wang YQ. Calcium signaling crosstalk between the endoplasmic reticulum and mitochondria, a new drug development strategies of kidney diseases. Biochem Pharmacol 2024; 225:116278. [PMID: 38740223 DOI: 10.1016/j.bcp.2024.116278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/25/2024] [Accepted: 05/10/2024] [Indexed: 05/16/2024]
Abstract
Calcium (Ca2+) acts as a second messenger and constitutes a complex and large information exchange system between the endoplasmic reticulum (ER) and mitochondria; this process is involved in various life activities, such as energy metabolism, cell proliferation and apoptosis. Increasing evidence has suggested that alterations in Ca2+ crosstalk between the ER and mitochondria, including alterations in ER and mitochondrial Ca2+ channels and related Ca2+ regulatory proteins, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), inositol 1,4,5-trisphosphate receptor (IP3R), and calnexin (CNX), are closely associated with the development of kidney disease. Therapies targeting intracellular Ca2+ signaling have emerged as an emerging field in the treatment of renal diseases. In this review, we focused on recent advances in Ca2+ signaling, ER and mitochondrial Ca2+ monitoring methods and Ca2+ homeostasis in the development of renal diseases and sought to identify new targets and insights for the treatment of renal diseases by targeting Ca2+ channels or related Ca2+ regulatory proteins.
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Affiliation(s)
- Wen-Di Ge
- Research Division of Clinical Pharmacology, the First Affiliated Hospital of Nanjing Medical University & Jiangsu Province Hospital, Nanjing, China; Department of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Tian-Tian Du
- Research Division of Clinical Pharmacology, the First Affiliated Hospital of Nanjing Medical University & Jiangsu Province Hospital, Nanjing, China; Department of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Cao-Yang Wang
- Research Division of Clinical Pharmacology, the First Affiliated Hospital of Nanjing Medical University & Jiangsu Province Hospital, Nanjing, China; Department of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Lu-Ning Sun
- Research Division of Clinical Pharmacology, the First Affiliated Hospital of Nanjing Medical University & Jiangsu Province Hospital, Nanjing, China; Department of Pharmacy, Nanjing Medical University, Nanjing, China.
| | - Yong-Qing Wang
- Research Division of Clinical Pharmacology, the First Affiliated Hospital of Nanjing Medical University & Jiangsu Province Hospital, Nanjing, China; Department of Pharmacy, Nanjing Medical University, Nanjing, China.
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4
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Ponnusamy T, Velusamy P, Shanmughapriya S. Mrs2-mediated mitochondrial magnesium uptake is essential for the regulation of MCU-mediated mitochondrial Ca 2+ uptake and viability. Mitochondrion 2024; 76:101877. [PMID: 38599304 DOI: 10.1016/j.mito.2024.101877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/07/2024] [Accepted: 04/07/2024] [Indexed: 04/12/2024]
Abstract
Mitochondrial Ca2+ uptake is essential in regulating bioenergetics, cell death, and cytosolic Ca2+ transients. Mitochondrial Calcium Uniporter (MCU) mediates the mitochondrial Ca2+ uptake. Though MCU regulation by MICUs is unequivocally established, there needs to be more knowledge of whether divalent cations regulate MCU. Here, we set out to understand the mitochondrial matrix Mg2+-dependent regulation of MCU activity. We showed that decreased matrix [Mg2+] is associated with increased MCU activity and significantly prompted mitochondrial permeability transition pore opening. Our findings support the critical role of mMg2+ in regulating MCU activity.
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Affiliation(s)
- Thiruvelselvan Ponnusamy
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Prema Velusamy
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Santhanam Shanmughapriya
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.
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5
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Wang J, Jiang J, Hu H, Chen L. MCU complex: Exploring emerging targets and mechanisms of mitochondrial physiology and pathology. J Adv Res 2024:S2090-1232(24)00075-4. [PMID: 38417574 DOI: 10.1016/j.jare.2024.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/16/2024] [Accepted: 02/17/2024] [Indexed: 03/01/2024] Open
Abstract
BACKGROUND Globally, the onset and progression of multiple human diseases are associated with mitochondrial dysfunction and dysregulation of Ca2+ uptake dynamics mediated by the mitochondrial calcium uniporter (MCU) complex, which plays a key role in mitochondrial dysfunction. Despite relevant studies, the underlying pathophysiological mechanisms have not yet been fully elucidated. AIM OF REVIEW This article provides an in-depth analysis of the current research status of the MCU complex, focusing on its molecular composition, regulatory mechanisms, and association with diseases. In addition, we conducted an in-depth analysis of the regulatory effects of agonists, inhibitors, and traditional Chinese medicine (TCM) monomers on the MCU complex and their application prospects in disease treatment. From the perspective of medicinal chemistry, we conducted an in-depth analysis of the structure-activity relationship between these small molecules and MCU and deduced potential pharmacophores and binding pockets. Simultaneously, key structural domains of the MCU complex in Homo sapiens were identified. We also studied the functional expression of the MCU complex in Drosophila, Zebrafish, and Caenorhabditis elegans. These analyses provide a basis for exploring potential treatment strategies targeting the MCU complex and provide strong support for the development of future precision medicine and treatments. KEY SCIENTIFIC CONCEPTS OF REVIEW The MCU complex exhibits varying behavior across different tissues and plays various roles in metabolic functions. It consists of six MCU subunits, an essential MCU regulator (EMRE), and solute carrier 25A23 (SLC25A23). They regulate processes, such as mitochondrial Ca2+ (mCa2+) uptake, mitochondrial adenosine triphosphate (ATP) production, calcium dynamics, oxidative stress (OS), and cell death. Regulation makes it a potential target for treating diseases, especially cardiovascular diseases, neurodegenerative diseases, inflammatory diseases, metabolic diseases, and tumors.
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Affiliation(s)
- Jin Wang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, School of Pharmaceutical Science, Hengyang Medical College, University of South China, Hengyang 421001, China
| | - Jinyong Jiang
- Department of Pharmacy, The First Affiliated Hospital of Jishou University, Jishou 416000, China
| | - Haoliang Hu
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, School of Pharmaceutical Science, Hengyang Medical College, University of South China, Hengyang 421001, China; College of Medicine, Hunan University of Arts and Science, Changde 415000, China.
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, School of Pharmaceutical Science, Hengyang Medical College, University of South China, Hengyang 421001, China.
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6
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Bulthuis EP, Adjobo-Hermans MJW, de Potter B, Hoogstraten S, Wezendonk LHT, Tutakhel OAZ, Wintjes LT, van den Heuvel B, Willems PHGM, Kamsteeg EJ, Gozalbo MER, Sallevelt SCEH, Koudijs SM, Nicolai J, de Bie CI, Hoogendijk JE, Koopman WJH, Rodenburg RJ. SMDT1 variants impair EMRE-mediated mitochondrial calcium uptake in patients with muscle involvement. Biochim Biophys Acta Mol Basis Dis 2023; 1869:166808. [PMID: 37454773 DOI: 10.1016/j.bbadis.2023.166808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/26/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
Ionic calcium (Ca2+) is a key messenger in signal transduction and its mitochondrial uptake plays an important role in cell physiology. This uptake is mediated by the mitochondrial Ca2+ uniporter (MCU), which is regulated by EMRE (essential MCU regulator) encoded by the SMDT1 (single-pass membrane protein with aspartate rich tail 1) gene. This work presents the genetic, clinical and cellular characterization of two patients harbouring SMDT1 variants and presenting with muscle problems. Analysis of patient fibroblasts and complementation experiments demonstrated that these variants lead to absence of EMRE protein, induce MCU subcomplex formation and impair mitochondrial Ca2+ uptake. However, the activity of oxidative phosphorylation enzymes, mitochondrial morphology and membrane potential, as well as routine/ATP-linked respiration were not affected. We hypothesize that the muscle-related symptoms in the SMDT1 patients result from aberrant mitochondrial Ca2+ uptake.
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Affiliation(s)
- Elianne P Bulthuis
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Merel J W Adjobo-Hermans
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Bastiaan de Potter
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Saskia Hoogstraten
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands; Human and Animal Physiology, Wageningen University & Research, 6700 AH Wageningen, the Netherlands
| | - Lisanne H T Wezendonk
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Omar A Z Tutakhel
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Liesbeth T Wintjes
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Bert van den Heuvel
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Peter H G M Willems
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - M Estela Rubio Gozalbo
- Department of Pediatrics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands; Department of Clinical Genetics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Suzanne M Koudijs
- Department of Neurology, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Joost Nicolai
- Department of Neurology, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Charlotte I de Bie
- Department of Genetics, University Medical Centre Utrecht, 3508 AB Utrecht, the Netherlands
| | - Jessica E Hoogendijk
- Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, 3584 CG Utrecht, the Netherlands
| | - Werner J H Koopman
- Human and Animal Physiology, Wageningen University & Research, 6700 AH Wageningen, the Netherlands; Department of Pediatrics, Amalia Children's Hospital, Radboud Center for Mitochondrial Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands.
| | - Richard J Rodenburg
- Department of Pediatrics, Amalia Children's Hospital, Radboud Center for Mitochondrial Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands.
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7
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Zhang S, Guo Y, Fidelito G, Robinson DR, Liang C, Lim R, Bichler Z, Guo R, Wu G, Xu H, Zhou QD, Singh BK, Yen P, Kappei D, Stroud DA, Ho L. LINC00116-encoded microprotein mitoregulin regulates fatty acid metabolism at the mitochondrial outer membrane. iScience 2023; 26:107558. [PMID: 37664623 PMCID: PMC10469944 DOI: 10.1016/j.isci.2023.107558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 07/04/2023] [Accepted: 08/02/2023] [Indexed: 09/05/2023] Open
Abstract
LINC00116 encodes a microprotein first identified as Mitoregulin (MTLN), where it was reported to localize to the inner membrane of mitochondria to regulate fatty acid oxidation and oxidative phosphorylation. These initial discoveries were followed by reports with differing findings about its molecular functions and submitochondrial localization. To clarify the apparent discrepancies, we constructed multiple orthogonal methods of determining the localization of MTLN, including split GFP-based reporters that enable efficient and reliable topology analyses for microproteins. These methods unequivocally demonstrate MTLN primarily localizes to the outer membrane of mitochondria, where it interacts with enzymes of fatty acid metabolism including CPT1B and CYB5B. Loss of MTLN causes the accumulation of very long-chain fatty acids (VLCFAs), especially docosahexaenoic acid (DHA). Intriguingly, loss of MTLN protects mice against western diet/fructose-induced insulin-resistance, suggests a protective effect of VLCFAs in this context. MTLN thus serves as an attractive target to control the catabolism of VLCFAs.
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Affiliation(s)
- Shan Zhang
- Department of Biochemistry, Department of Cardiology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Yabo Guo
- Department of Biochemistry, Department of Cardiology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Gio Fidelito
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - David R.L. Robinson
- Department of Biochemistry and Pharmacology, The Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Chao Liang
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Radiance Lim
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Zoë Bichler
- Behavioral Neuroscience Laboratory, National Neuroscience Institute, Singapore 308433, Singapore
| | - Ruiyang Guo
- Department of Biochemistry, Department of Cardiology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Gaoqi Wu
- Institute of Immunology, Department of Surgical Oncology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - He Xu
- Institute of Immunology, Department of Surgical Oncology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Quan D. Zhou
- Institute of Immunology, Department of Surgical Oncology of The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Brijesh K. Singh
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Paul Yen
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Dennis Kappei
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
- NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
| | - David A. Stroud
- Department of Biochemistry and Pharmacology, The Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3010, Australia
| | - Lena Ho
- Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
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8
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Ponnusamy T, Velusamy P, Kumar A, Morris D, Zhang X, Ning G, Klinger M, Copper JE, Rajan S, Cheung JY, Natarajaseenivasan K, Mnatsakanyan N, Shanmughapriya S. Mitochondrial Magnesium is the cationic rheostat for MCU-mediated mitochondrial Ca 2+ uptake. RESEARCH SQUARE 2023:rs.3.rs-3088175. [PMID: 37502932 PMCID: PMC10371168 DOI: 10.21203/rs.3.rs-3088175/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Calcium (Ca2+) uptake by mitochondria is essential in regulating bioenergetics, cell death, and cytosolic Ca2+ transients. Mitochondrial Calcium Uniporter (MCU) mediates the mitochondrial Ca2+ uptake. MCU is a heterooligomeric complex with a pore-forming component and accessory proteins required for channel activity. Though MCU regulation by MICUs is unequivocally established, there needs to be more knowledge of whether divalent cations regulate MCU. Here we set out to understand the mitochondrial matrix Mg2+-dependent regulation of MCU activity. We showed Mrs2 as the authentic mammalian mitochondrial Mg2+ channel using the planar lipid bilayer recordings. Using a liver-specific Mrs2 KO mouse model, we showed that decreased matrix [Mg2+] is associated with increased MCU activity and matrix Ca2+ overload. The disruption of Mg2+dependent MCU regulation significantly prompted mitochondrial permeability transition pore opening-mediated cell death during tissue IR injury. Our findings support a critical role for mMg2+ in regulating MCU activity and attenuating mCa2+ overload.
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Affiliation(s)
- Thiruvelselvan Ponnusamy
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Prema Velusamy
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Amrendra Kumar
- Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Daniel Morris
- Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Xueqian Zhang
- Cardiovascular Medicine, Department of Medicine, UMass Chan Medical School, Worcester, MA 01655, USA
| | - Gang Ning
- Microscopy Core Facility, Penn State Huck Institutes of the Life Sciences, University Park, PA 16802, USA
| | - Marianne Klinger
- Department of Pathology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Jean E. Copper
- Department of Pathology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Sudarsan Rajan
- Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Joseph Y Cheung
- Department of Renal Medicine, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Nelli Mnatsakanyan
- Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
| | - Santhanam Shanmughapriya
- Heart and Vascular Institute, Department of Medicine, Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA
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9
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Moon DO. Calcium's Role in Orchestrating Cancer Apoptosis: Mitochondrial-Centric Perspective. Int J Mol Sci 2023; 24:ijms24108982. [PMID: 37240331 DOI: 10.3390/ijms24108982] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
Calcium is an essential intracellular messenger that plays a vital role in controlling a broad range of cellular processes, including apoptosis. This review offers an in-depth analysis of calcium's multifaceted role in apoptosis regulation, focusing on the associated signaling pathways and molecular mechanisms. We will explore calcium's impact on apoptosis through its effects on different cellular compartments, such as the mitochondria and endoplasmic reticulum (ER), and discuss the connection between calcium homeostasis and ER stress. Additionally, we will highlight the interplay between calcium and various proteins, including calpains, calmodulin, and Bcl-2 family members, and the role of calcium in regulating caspase activation and pro-apoptotic factor release. By investigating the complex relationship between calcium and apoptosis, this review aims to deepen our comprehension of the fundamental processes, and pinpointing possible treatment options for illnesses associated with imbalanced cell death is crucial.
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Affiliation(s)
- Dong-Oh Moon
- Department of Biology Education, Daegu University, 201, Daegudae-ro, Gyeongsan-si 38453, Gyeongsangbuk-do, Republic of Korea
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10
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Szabo I, Szewczyk A. Mitochondrial Ion Channels. Annu Rev Biophys 2023; 52:229-254. [PMID: 37159294 DOI: 10.1146/annurev-biophys-092622-094853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Mitochondria are involved in multiple cellular tasks, such as ATP synthesis, metabolism, metabolite and ion transport, regulation of apoptosis, inflammation, signaling, and inheritance of mitochondrial DNA. The majority of the correct functioning of mitochondria is based on the large electrochemical proton gradient, whose component, the inner mitochondrial membrane potential, is strictly controlled by ion transport through mitochondrial membranes. Consequently, mitochondrial function is critically dependent on ion homeostasis, the disturbance of which leads to abnormal cell functions. Therefore, the discovery of mitochondrial ion channels influencing ion permeability through the membrane has defined a new dimension of the function of ion channels in different cell types, mainly linked to the important tasks that mitochondrial ion channels perform in cell life and death. This review summarizes studies on animal mitochondrial ion channels with special focus on their biophysical properties, molecular identity, and regulation. Additionally, the potential of mitochondrial ion channels as therapeutic targets for several diseases is briefly discussed.
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Affiliation(s)
- Ildiko Szabo
- Department of Biology, University of Padova, Italy;
| | - Adam Szewczyk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland;
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11
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Rodríguez-Prados M, Berezhnaya E, Castromonte MT, Menezes-Filho SL, Paillard M, Hajnóczky G. MICU1 occludes the mitochondrial calcium uniporter in divalent-free conditions. Proc Natl Acad Sci U S A 2023; 120:e2218999120. [PMID: 37126688 PMCID: PMC10175726 DOI: 10.1073/pnas.2218999120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 03/30/2023] [Indexed: 05/03/2023] Open
Abstract
Mitochondrial Ca2+ uptake is mediated by the mitochondrial uniporter complex (mtCU) that includes a tetramer of the pore-forming subunit, MCU, a scaffold protein, EMRE, and the EF-hand regulatory subunit, MICU1 either homodimerized or heterodimerized with MICU2/3. MICU1 has been proposed to regulate Ca2+ uptake via the mtCU by physically occluding the pore and preventing Ca2+ flux at resting cytoplasmic [Ca2+] (free calcium concentration) and to increase Ca2+ flux at high [Ca2+] due to cooperative activation of MICUs EF-hands. However, mtCU and MICU1 functioning when its EF-hands are unoccupied by Ca2+ is poorly studied due to technical limitations. To overcome this barrier, we have studied the mtCU in divalent-free conditions by assessing the Ru265-sensitive Na+ influx using fluorescence-based measurement of mitochondrial matrix [Na+] (free sodium concentration) rise and the ensuing depolarization and swelling. We show an increase in all these measures of Na+ uptake in MICU1KO cells as compared to wild-type (WT) and rescued MICU1KO HEK cells. However, mitochondria in WT cells and MICU1 stable-rescued cells still allowed some Ru265-sensitive Na+ influx that was prevented by MICU1 in excess upon acute overexpression. Thus, MICU1 restricts the cation flux across the mtCU in the absence of Ca2+, but even in cells with high endogenous MICU1 expression such as HEK, some mtCU seem to lack MICU1-dependent gating. We also show rearrangement of the mtCU and altered number of functional channels in MICU1KO and different rescues, and loss of MICU1 during mitoplast preparation, that together might have obscured the pore-blocking function of MICU1 in divalent-free conditions in previous studies.
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Affiliation(s)
- Macarena Rodríguez-Prados
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Elena Berezhnaya
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Maria Teresa Castromonte
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Sergio L. Menezes-Filho
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
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CKII Control of Axonal Plasticity Is Mediated by Mitochondrial Ca 2+ via Mitochondrial NCLX. Cells 2022; 11:cells11243990. [PMID: 36552754 PMCID: PMC9777275 DOI: 10.3390/cells11243990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/11/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial Ca2+ efflux by NCLX is a critical rate-limiting step in mitochondria signaling. We previously showed that NCLX is phosphorylated at a putative Casein Kinase 2 (CKII) site, the serine 271 (S271). Here, we asked if NCLX is regulated by CKII and interrogated the physiological implications of this control. We found that CKII inhibitors down-regulated NCLX-dependent Ca2+ transport activity in SH-SY5Y neuronal cells and primary hippocampal neurons. Furthermore, we show that the CKII phosphomimetic mutants on NCLX inhibited (S271A) and constitutively activated (S271D) NCLX transport, respectively, rendering it insensitive to CKII inhibition. These phosphomimetic NCLX mutations also control the allosteric regulation of NCLX by mitochondrial membrane potential (ΔΨm). Since the omnipresent CKII is necessary for modulating the plasticity of the axon initial segment (AIS), we interrogated, in hippocampal neurons, if NCLX is required for this process. Similarly to WT neurons, NCLX-KO neurons can exhibit homeostatic plasticity following M-channel block. However, while WT neurons utilize a CKII-sensitive distal relocation of AIS Na+ and Kv7 channels to decrease their intrinsic excitability, we did not observe such translocation in NCLX-KO neurons. Thus, our results indicate that NCLX is regulated by CKII and is a crucial link between CKII signaling and fast neuronal plasticity.
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13
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Bertolini MS, Docampo R. MICU1 and MICU2 potentiation of Ca 2+ uptake by the mitochondrial Ca 2+ uniporter of Trypanosoma cruzi and its inhibition by Mg 2. Cell Calcium 2022; 107:102654. [PMID: 36166935 PMCID: PMC10433726 DOI: 10.1016/j.ceca.2022.102654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/30/2022]
Abstract
The mitochondrial Ca2+ uptake, which is important to regulate bioenergetics, cell death and cytoplasmic Ca2+ signaling, is mediated via the calcium uniporter complex (MCUC). In animal cells the MCUC is regulated by the mitochondrial calcium uptake 1 and 2 dimer (MICU1/MICU2), which has been proposed to act as gatekeeper preventing mitochondrial Ca2+ overload at low cytosolic Ca2+ levels. In contrast to animal cells, knockout of either MICU1 or MICU2 in Trypanosoma cruzi, the etiologic agent of Chagas disease, did not allow Ca2+ uptake at low extramitochondrial Ca2+ concentrations ([Ca2+]ext) and it was though that in the absence of one MICU the other would replace its role. However, previous attempts to knockout both genes were unsuccessful. Here, we designed a strategy to generate TcMICU1/TcMICU2 double knockout cell lines using CRISPR/Cas9 genome editing. Ablation of both genes was confirmed by PCR and Southern blot analyses. The absence of both proteins did not allow Ca2+ uptake at low [Ca2+]ext, significantly decreased the mitochondrial Ca2+ uptake at different [Ca2+]ext, without dissipation of the mitochondrial membrane potential, and increased the [Ca2+]ext set point needed for Ca2+ uptake, as we have seen with TcMICU1-KO and TcMICU2-KO cells. Mg2+ was found to be a negative regulator of MCUC-mediated mitochondrial Ca2+ uptake at different [Ca2+]ext. Occlusion of the MCUC pore by Mg2+ could partially explain the lack of mitochondrial Ca2+ uptake at low [Ca2+]ext in TcMICU1/TcMICU2-KO cells. In addition, TcMICU1/TcMICU2-KO epimastigotes had a lower growth rate, while infective trypomastigotes have a reduced capacity to invade host cells and to replicate within them as amastigotes.
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Affiliation(s)
- Mayara S Bertolini
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States.
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14
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Zhang L, Dietsche F, Seitaj B, Rojas-Charry L, Latchman N, Tomar D, Wüst RC, Nickel A, Frauenknecht KB, Schoser B, Schumann S, Schmeisser MJ, Vom Berg J, Buch T, Finger S, Wenzel P, Maack C, Elrod JW, Parys JB, Bultynck G, Methner A. TMBIM5 loss of function alters mitochondrial matrix ion homeostasis and causes a skeletal myopathy. Life Sci Alliance 2022; 5:5/10/e202201478. [PMID: 35715207 PMCID: PMC9206080 DOI: 10.26508/lsa.202201478] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/25/2022] [Accepted: 05/31/2022] [Indexed: 01/13/2023] Open
Abstract
TMBIM5 deficiency reduces mitochondrial K+/H+ exchange. Mutation of the channel pore in mice destabilizes the protein and results in increased embryonic lethality and a skeletal myopathy. Ion fluxes across the inner mitochondrial membrane control mitochondrial volume, energy production, and apoptosis. TMBIM5, a highly conserved protein with homology to putative pH-dependent ion channels, is involved in the maintenance of mitochondrial cristae architecture, ATP production, and apoptosis. Here, we demonstrate that overexpressed TMBIM5 can mediate mitochondrial calcium uptake. Under steady-state conditions, loss of TMBIM5 results in increased potassium and reduced proton levels in the mitochondrial matrix caused by attenuated exchange of these ions. To identify the in vivo consequences of TMBIM5 dysfunction, we generated mice carrying a mutation in the channel pore. These mutant mice display increased embryonic or perinatal lethality and a skeletal myopathy which strongly correlates with tissue-specific disruption of cristae architecture, early opening of the mitochondrial permeability transition pore, reduced calcium uptake capability, and mitochondrial swelling. Our results demonstrate that TMBIM5 is an essential and important part of the mitochondrial ion transport system machinery with particular importance for embryonic development and muscle function.
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Affiliation(s)
- Li Zhang
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | | | - Bruno Seitaj
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Liliana Rojas-Charry
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Nadina Latchman
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Dhanendra Tomar
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Rob Ci Wüst
- Laboratory for Myology, Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Alexander Nickel
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Katrin Bm Frauenknecht
- Institute of Neuropathology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Benedikt Schoser
- Friedrich-Baur-Institute, Department of Neurology, LMU Clinic, Munich, Germany
| | - Sven Schumann
- Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Michael J Schmeisser
- Institute of Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Johannes Vom Berg
- Institute of Laboratory Animal Science, University of Zurich, Zürich, Switzerland
| | - Thorsten Buch
- Institute of Laboratory Animal Science, University of Zurich, Zürich, Switzerland
| | - Stefanie Finger
- Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Philip Wenzel
- Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,Department of Cardiology, Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
| | - Christoph Maack
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - John W Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Jan B Parys
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, KU Leuven, Laboratory of Molecular and Cellular Signaling, Leuven, Belgium
| | - Axel Methner
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
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15
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Bolaños P, Calderón JC. Excitation-contraction coupling in mammalian skeletal muscle: Blending old and last-decade research. Front Physiol 2022; 13:989796. [PMID: 36117698 PMCID: PMC9478590 DOI: 10.3389/fphys.2022.989796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The excitation–contraction coupling (ECC) in skeletal muscle refers to the Ca2+-mediated link between the membrane excitation and the mechanical contraction. The initiation and propagation of an action potential through the membranous system of the sarcolemma and the tubular network lead to the activation of the Ca2+-release units (CRU): tightly coupled dihydropyridine and ryanodine (RyR) receptors. The RyR gating allows a rapid, massive, and highly regulated release of Ca2+ from the sarcoplasmic reticulum (SR). The release from triadic places generates a sarcomeric gradient of Ca2+ concentrations ([Ca2+]) depending on the distance of a subcellular region from the CRU. Upon release, the diffusing Ca2+ has multiple fates: binds to troponin C thus activating the contractile machinery, binds to classical sarcoplasmic Ca2+ buffers such as parvalbumin, adenosine triphosphate and, experimentally, fluorescent dyes, enters the mitochondria and the SR, or is recycled through the Na+/Ca2+ exchanger and store-operated Ca2+ entry (SOCE) mechanisms. To commemorate the 7th decade after being coined, we comprehensively and critically reviewed “old”, historical landmarks and well-established concepts, and blended them with recent advances to have a complete, quantitative-focused landscape of the ECC. We discuss the: 1) elucidation of the CRU structures at near-atomic resolution and its implications for functional coupling; 2) reliable quantification of peak sarcoplasmic [Ca2+] using fast, low affinity Ca2+ dyes and the relative contributions of the Ca2+-binding mechanisms to the whole concert of Ca2+ fluxes inside the fibre; 3) articulation of this novel quantitative information with the unveiled structural details of the molecular machinery involved in mitochondrial Ca2+ handing to understand how and how much Ca2+ enters the mitochondria; 4) presence of the SOCE machinery and its different modes of activation, which awaits understanding of its magnitude and relevance in situ; 5) pharmacology of the ECC, and 6) emerging topics such as the use and potential applications of super-resolution and induced pluripotent stem cells (iPSC) in ECC. Blending the old with the new works better!
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Affiliation(s)
- Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
- *Correspondence: Juan C. Calderón,
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16
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Carreras-Sureda A, Kroemer G, Cardenas JC, Hetz C. Balancing energy and protein homeostasis at ER-mitochondria contact sites. Sci Signal 2022; 15:eabm7524. [DOI: 10.1126/scisignal.abm7524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The endoplasmic reticulum (ER) is the largest organelle of the cell and participates in multiple essential functions, including the production of secretory proteins, lipid synthesis, and calcium storage. Sustaining proteostasis requires an intimate coupling with energy production. Mitochondrial respiration evolved to be functionally connected to ER physiology through a physical interface between both organelles known as mitochondria-associated membranes. This quasi-synaptic structure acts as a signaling hub that tunes the function of both organelles in a bidirectional manner and controls proteostasis, cell death pathways, and mitochondrial bioenergetics. Here, we discuss the main signaling mechanisms governing interorganellar communication and their putative role in diseases including cancer and neurodegeneration.
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Affiliation(s)
- Amado Carreras-Sureda
- Department of Cell Physiology and Metabolism, University of Geneva, 1, rue Michel-Servet, 1211 Geneva, Switzerland
| | - Guido Kroemer
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, 75006 Paris, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, 94805 Villejuif, France
- Department of Biology, Institut du Cancer Paris CARPEM, Hôpital Européen Georges Pompidou, AP-HP, 75015 Paris, France
| | - Julio Cesar Cardenas
- Center for Integrative Biology, Mayor University, 7510041 Santiago, Chile
- Center for Geroscience, Brain Health, and Metabolism, 70086 Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA 94945, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Claudio Hetz
- Center for Geroscience, Brain Health, and Metabolism, 70086 Santiago, Chile
- Buck Institute for Research on Aging, Novato, CA 94945, USA
- Faculty of Medicine, Biomedical Neuroscience Institute, University of Chile, 70086 Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, 70086 Santiago, Chile
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17
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Allen JG, Tessem JS. Ca 2+ Sensors Assemble: Function of the MCU Complex in the Pancreatic Beta Cell. Cells 2022; 11:cells11131993. [PMID: 35805078 PMCID: PMC9265474 DOI: 10.3390/cells11131993] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 12/05/2022] Open
Abstract
The Mitochondrial Calcium Uniporter Complex (MCU Complex) is essential for β-cell function due to its role in sustaining insulin secretion. The MCU complex regulates mitochondrial Ca2+ influx, which is necessary for increased ATP production following cellular glucose uptake, keeps the cell membrane K+ channels closed following initial insulin release, and ultimately results in sustained insulin granule exocytosis. Dysfunction in Ca2+ regulation results in an inability to sustain insulin secretion. This review defines the functions, structure, and mutations associated with the MCU complex members mitochondrial calcium uniporter protein (MCU), essential MCU regulator (EMRE), mitochondrial calcium uptake 1 (MICU1), mitochondrial calcium uptake 2 (MICU2), and mitochondrial calcium uptake 3 (MICU3) in the pancreatic β-cell. This review provides a framework for further evaluation of the MCU complex in β-cell function and insulin secretion.
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18
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Jackson J, Wischhof L, Scifo E, Pellizzer A, Wang Y, Piazzesi A, Gentile D, Siddig S, Stork M, Hopkins CE, Händler K, Weis J, Roos A, Schultze JL, Nicotera P, Ehninger D, Bano D. SGPL1 stimulates VPS39 recruitment to the mitochondria in MICU1 deficient cells. Mol Metab 2022; 61:101503. [PMID: 35452878 PMCID: PMC9170783 DOI: 10.1016/j.molmet.2022.101503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/08/2022] [Accepted: 04/15/2022] [Indexed: 01/21/2023] Open
Abstract
Objective Mitochondrial “retrograde” signaling may stimulate organelle biogenesis as a compensatory adaptation to aberrant activity of the oxidative phosphorylation (OXPHOS) system. To maintain energy-consuming processes in OXPHOS deficient cells, alternative metabolic pathways are functionally coupled to the degradation, recycling and redistribution of biomolecules across distinct intracellular compartments. While transcriptional regulation of mitochondrial network expansion has been the focus of many studies, the molecular mechanisms promoting mitochondrial maintenance in energy-deprived cells remain poorly investigated. Methods We performed transcriptomics, quantitative proteomics and lifespan assays to identify pathways that are mechanistically linked to mitochondrial network expansion and homeostasis in Caenorhabditis elegans lacking the mitochondrial calcium uptake protein 1 (MICU-1/MICU1). To support our findings, we carried out biochemical and image analyses in mammalian cells and mouse-derived tissues. Results We report that micu-1(null) mutations impair the OXPHOS system and promote C. elegans longevity through a transcriptional program that is independent of the mitochondrial calcium uniporter MCU-1/MCU and the essential MCU regulator EMRE-1/EMRE. We identify sphingosine phosphate lyase SPL-1/SGPL1 and the ATFS-1-target HOPS complex subunit VPS-39/VPS39 as critical lifespan modulators of micu-1(null) mutant animals. Cross-species investigation indicates that SGPL1 upregulation stimulates VPS39 recruitment to the mitochondria, thereby enhancing mitochondria-lysosome contacts. Consistently, VPS39 downregulation compromises mitochondrial network maintenance and basal autophagic flux in MICU1 deficient cells. In mouse-derived muscles, we show that VPS39 recruitment to the mitochondria may represent a common signature associated with altered OXPHOS system. Conclusions Our findings reveal a previously unrecognized SGPL1/VPS39 axis that stimulates intracellular organelle interactions and sustains autophagy and mitochondrial homeostasis in OXPHOS deficient cells. micu-1(null) nematodes are long-lived mitochondrial mutants. MICU-1/MICU1 deficiency stimulates VPS-39/VPS39 and SPL-1/SGPL1 upregulation. VPS-39 sustains mitochondrial network expansion in micu-1(null) nematodes. VPS39 and SGPL1 expression influences mitochondria-lysosome contact sites in MICU1 deficient cells. VPS39/SGPL1 signaling may be a common signature of mitochondrial deficient cells.
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Affiliation(s)
- Joshua Jackson
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Lena Wischhof
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Enzo Scifo
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Anna Pellizzer
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Yiru Wang
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Antonia Piazzesi
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Debora Gentile
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Sana Siddig
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Miriam Stork
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | - Kristian Händler
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; PRECISE Platform for Single Cell Genomics and Epigenomics, German Center for Neurodegenerative Diseases (DZNE), University of Bonn, Bonn, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Andreas Roos
- Universitätsklinikum Essen and Universität Duisburg-Essen, Essen, Germany
| | - Joachim L Schultze
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; PRECISE Platform for Single Cell Genomics and Epigenomics, German Center for Neurodegenerative Diseases (DZNE), University of Bonn, Bonn, Germany; LIMES Institute, Department for Genomics and Immunoregulation, University of Bonn, Bonn, Germany
| | | | - Dan Ehninger
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Daniele Bano
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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19
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Mitochondrial Ca 2+ Homeostasis: Emerging Roles and Clinical Significance in Cardiac Remodeling. Int J Mol Sci 2022; 23:ijms23063025. [PMID: 35328444 PMCID: PMC8954803 DOI: 10.3390/ijms23063025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondria are the sites of oxidative metabolism in eukaryotes where the metabolites of sugars, fats, and amino acids are oxidized to harvest energy. Notably, mitochondria store Ca2+ and work in synergy with organelles such as the endoplasmic reticulum and extracellular matrix to control the dynamic balance of Ca2+ concentration in cells. Mitochondria are the vital organelles in heart tissue. Mitochondrial Ca2+ homeostasis is particularly important for maintaining the physiological and pathological mechanisms of the heart. Mitochondrial Ca2+ homeostasis plays a key role in the regulation of cardiac energy metabolism, mechanisms of death, oxygen free radical production, and autophagy. The imbalance of mitochondrial Ca2+ balance is closely associated with cardiac remodeling. The mitochondrial Ca2+ uniporter (mtCU) protein complex is responsible for the uptake and release of mitochondrial Ca2+ and regulation of Ca2+ homeostasis in mitochondria and consequently, in cells. This review summarizes the mechanisms of mitochondrial Ca2+ homeostasis in physiological and pathological cardiac remodeling and the regulatory effects of the mitochondrial calcium regulatory complex on cardiac energy metabolism, cell death, and autophagy, and also provides the theoretical basis for mitochondrial Ca2+ as a novel target for the treatment of cardiovascular diseases.
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20
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Costiniti V, Bomfim GHS, Neginskaya M, Son GY, Mitaishvili E, Giacomello M, Pavlov E, Lacruz RS. Mitochondria modulate ameloblast Ca 2+ signaling. FASEB J 2022; 36:e22169. [PMID: 35084775 PMCID: PMC8852362 DOI: 10.1096/fj.202100602r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 12/22/2021] [Accepted: 01/07/2022] [Indexed: 02/03/2023]
Abstract
The role of mitochondria in enamel, the most mineralized tissue in the body, is poorly defined. Enamel is formed by ameloblast cells in two main sequential stages known as secretory and maturation. Defining the physiological features of each stage is essential to understand mineralization. Here, we analyzed functional features of mitochondria in rat primary secretory and maturation-stage ameloblasts focusing on their role in Ca2+ signaling. Quantification of the Ca2+ stored in the mitochondria by trifluoromethoxy carbonylcyanide phenylhydrazone stimulation was comparable in both stages. The release of endoplasmic reticulum Ca2+ pools by adenosine triphosphate in rhod2AM-loaded cells showed similar mitochondrial Ca2+ (m Ca2+ ) uptake. However, m Ca2+ extrusion via Na+ -Li+ -Ca2+ exchanger was more prominent in maturation. To address if m Ca2+ uptake via the mitochondrial Ca2+ uniporter (MCU) played a role in cytosolic Ca2+ (c Ca2+ ) buffering, we stimulated Ca2+ influx via the store-operated Ca2+ entry (SOCE) and blocked MCU with the inhibitor Ru265. This inhibitor was first tested using the enamel cell line LS8 cells. Ru265 prevented c Ca2+ clearance in permeabilized LS8 cells like ruthenium red, and it did not affect ΔΨm in intact cells. In primary ameloblasts, SOCE stimulation elicited a significantly higher m Ca2+ uptake in maturation ameloblasts. The uptake of Ca2+ into the mitochondria was dramatically decreased in the presence of Ru265. Combined, these results suggest an increased mitochondrial Ca2+ handling in maturation but only upon stimulation of Ca2+ influx via SOCE. These functional studies provide insights not only on the role of mitochondria in ameloblast Ca2+ physiology, but also advance the concept that SOCE and m Ca2+ uptake are complementary processes in biological mineralization.
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Affiliation(s)
- Veronica Costiniti
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Guilherme H. S. Bomfim
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Maria Neginskaya
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Ga-Yeon Son
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Erna Mitaishvili
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Marta Giacomello
- Department of Biology, University of Padova, Padua, Italy,Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Evgeny Pavlov
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
| | - Rodrigo S. Lacruz
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
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21
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Zhang Z, Luo Z, Yu L, Xiao Y, Liu S, Aluo Z, Ma Z, Huang L, Xiao L, Jia M, Song Z, Zhang H, Li Y, Zhou L. Ru360 and Mitoxantrone inhibit MCU channel to relieve liver steatosis induced by high-fat diet. Br J Pharmacol 2021; 179:2678-2696. [PMID: 34862596 DOI: 10.1111/bph.15767] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Nonalcoholic fatty liver disease (NAFLD) affects over 25% of the general population and lacks an effective treatment. Recent evidence implicates disrupted mitochondrial calcium homeostasis in the pathogenesis of hepatic steatosis. EXPERIMENTAL APPROACH In this study, mitochondrial calcium uniporter (MCU) was inhibited through classical genetic approaches, viral vectors or small molecule inhibitors in vivo to study its role in hepatic steatosis induced by HFD. In vitro, MCU was overexpressed or inhibited to change mitochondrial calcium homeostasis; endoplasmic reticulum-mitochondrial linker was adopted to increase mitochondria-associated membranes (MAM); and MICU1-EF hand mutant was used to decrease the sensitivity of mitochondrial calcium uptake 1 (MICU1) to calcium and block MCU channel. KEY RESULTS Here we found that inhibition of liver MCU by AAV virus and classical genetic approaches can alleviate HFD-induced liver steatosis. MCU regulates mitochondrial calcium homeostasis and affects lipid accumulation in liver cells. In addition, a HFD in mice enlarged the MAM. The high calcium environment produced by MAM invalidated the function of MICU1 and led to persistent open of MCU channels. Therefore, it caused mitochondrial calcium overload and liver fat deposition. Inhibition of MAM and MCU alleviated HFD-induced hepatic steatosis. MCU inhibitors (Ru360 and mitoxantrone) can block MCU channels and reduce mitochondrial calcium levels. Intraperitoneal injection of MCU inhibitors (0.01 μM/kg bodyweight) can alleviate HFD-induced hepatic steatosis. CONCLUSION AND IMPLICATIONS These findings provide molecular insights into the way HFD disrupts mitochondrial calcium homeostasis and identified MCU as a promising drug target for the treatment of hepatic steatosis.
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Affiliation(s)
- Zhiwang Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Zupeng Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Lin Yu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Yang Xiao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Siqi Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Zhier Aluo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Zeqiang Ma
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Liang Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Lianggui Xiao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Mengting Jia
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Ziyi Song
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Haojie Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Yixing Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
| | - Lei Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, P.R. China
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22
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Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer, and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport, and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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23
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Gómez-Valadés AG, Pozo M, Varela L, Boudjadja MB, Ramírez S, Chivite I, Eyre E, Haddad-Tóvolli R, Obri A, Milà-Guasch M, Altirriba J, Schneeberger M, Imbernón M, Garcia-Rendueles AR, Gama-Perez P, Rojo-Ruiz J, Rácz B, Alonso MT, Gomis R, Zorzano A, D'Agostino G, Alvarez CV, Nogueiras R, Garcia-Roves PM, Horvath TL, Claret M. Mitochondrial cristae-remodeling protein OPA1 in POMC neurons couples Ca 2+ homeostasis with adipose tissue lipolysis. Cell Metab 2021; 33:1820-1835.e9. [PMID: 34343501 PMCID: PMC8432968 DOI: 10.1016/j.cmet.2021.07.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 05/14/2021] [Accepted: 07/09/2021] [Indexed: 01/21/2023]
Abstract
Appropriate cristae remodeling is a determinant of mitochondrial function and bioenergetics and thus represents a crucial process for cellular metabolic adaptations. Here, we show that mitochondrial cristae architecture and expression of the master cristae-remodeling protein OPA1 in proopiomelanocortin (POMC) neurons, which are key metabolic sensors implicated in energy balance control, is affected by fluctuations in nutrient availability. Genetic inactivation of OPA1 in POMC neurons causes dramatic alterations in cristae topology, mitochondrial Ca2+ handling, reduction in alpha-melanocyte stimulating hormone (α-MSH) in target areas, hyperphagia, and attenuated white adipose tissue (WAT) lipolysis resulting in obesity. Pharmacological blockade of mitochondrial Ca2+ influx restores α-MSH and the lipolytic program, while improving the metabolic defects of mutant mice. Chemogenetic manipulation of POMC neurons confirms a role in lipolysis control. Our results unveil a novel axis that connects OPA1 in POMC neurons with mitochondrial cristae, Ca2+ homeostasis, and WAT lipolysis in the regulation of energy balance.
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Affiliation(s)
- Alicia G Gómez-Valadés
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
| | - Macarena Pozo
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Luis Varela
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Mehdi Boutagouga Boudjadja
- Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, M13 9PT Manchester, UK
| | - Sara Ramírez
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Iñigo Chivite
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Elena Eyre
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Roberta Haddad-Tóvolli
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Arnaud Obri
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Maria Milà-Guasch
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Jordi Altirriba
- Laboratory of Metabolism, Department of Internal Medicine Specialties, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Marc Schneeberger
- Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Mónica Imbernón
- Department of Physiology, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela, Instituto de Investigación Sanitaria (IDIS), 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Madrid, Spain
| | - Angela R Garcia-Rendueles
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela, Instituto de Investigación Sanitaria (IDIS), 15782 Santiago de Compostela, Spain
| | - Pau Gama-Perez
- Departament de Ciències Fisiològiques, Universitat de Barcelona, 08907 Barcelona, Spain; Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L'Hospitalet de Llobregat, Spain
| | - Jonathan Rojo-Ruiz
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), 47003 Valladolid, Spain
| | - Bence Rácz
- Department of Anatomy and Histology, University of Veterinary Medicine, 1078 Budapest, Hungary
| | - Maria Teresa Alonso
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), 47003 Valladolid, Spain
| | - Ramon Gomis
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Department of Endocrinology and Nutrition, Hospital Clínic, School of Medicine, University of Barcelona, 08036 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Antonio Zorzano
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Giuseppe D'Agostino
- Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, M13 9PT Manchester, UK
| | - Clara V Alvarez
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela, Instituto de Investigación Sanitaria (IDIS), 15782 Santiago de Compostela, Spain
| | - Rubén Nogueiras
- Department of Physiology, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela, Instituto de Investigación Sanitaria (IDIS), 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Madrid, Spain
| | - Pablo M Garcia-Roves
- Departament de Ciències Fisiològiques, Universitat de Barcelona, 08907 Barcelona, Spain; Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L'Hospitalet de Llobregat, Spain
| | - Tamas L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy and Histology, University of Veterinary Medicine, 1078 Budapest, Hungary
| | - Marc Claret
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain; School of Medicine, Universitat de Barcelona, 08036 Barcelona, Spain.
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24
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Garg V, Suzuki J, Paranjpe I, Unsulangi T, Boyman L, Milescu LS, Lederer WJ, Kirichok Y. The mechanism of MICU-dependent gating of the mitochondrial Ca 2+uniporter. eLife 2021; 10:e69312. [PMID: 34463251 PMCID: PMC8437439 DOI: 10.7554/elife.69312] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 08/09/2021] [Indexed: 12/11/2022] Open
Abstract
Ca2+ entry into mitochondria is through the mitochondrial calcium uniporter complex (MCUcx), a Ca2+-selective channel composed of five subunit types. Two MCUcx subunits (MCU and EMRE) span the inner mitochondrial membrane, while three Ca2+-regulatory subunits (MICU1, MICU2, and MICU3) reside in the intermembrane space. Here, we provide rigorous analysis of Ca2+ and Na+ fluxes via MCUcx in intact isolated mitochondria to understand the function of MICU subunits. We also perform direct patch clamp recordings of macroscopic and single MCUcx currents to gain further mechanistic insights. This comprehensive analysis shows that the MCUcx pore, composed of the EMRE and MCU subunits, is not occluded nor plugged by MICUs during the absence or presence of extramitochondrial Ca2+ as has been widely reported. Instead, MICUs potentiate activity of MCUcx as extramitochondrial Ca2+ is elevated. MICUs achieve this by modifying the gating properties of MCUcx allowing it to spend more time in the open state.
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Affiliation(s)
- Vivek Garg
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
- Department of Physiology, University of MarylandBaltimoreUnited States
| | - Junji Suzuki
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Ishan Paranjpe
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Tiffany Unsulangi
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Liron Boyman
- Department of Physiology, University of MarylandBaltimoreUnited States
| | - Lorin S Milescu
- Department of Biology, University of MarylandCollege ParkUnited States
| | | | - Yuriy Kirichok
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
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25
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Wang Y, Li X, Zhao F. MCU-Dependent mROS Generation Regulates Cell Metabolism and Cell Death Modulated by the AMPK/PGC-1α/SIRT3 Signaling Pathway. Front Med (Lausanne) 2021; 8:674986. [PMID: 34307407 PMCID: PMC8299052 DOI: 10.3389/fmed.2021.674986] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
The mitochondrial calcium uniporter is an intensively investigated calcium channel, and its molecular components, structural features, and encoded genes have long been explored. Further studies have shown that the mitochondrial calcium unidirectional transporter (MCU) is a macromolecular complex related to intracellular and extracellular calcium regulation. Based on the current understanding, the MCU is crucial for maintaining cytosolic Ca2+ (cCa2+) homeostasis by modulating mitochondrial Ca2+ (mCa2+) uptake. The elevation of MCU-induced calcium levels is confirmed to be the main cause of mitochondrial reactive oxygen species (mROS) generation, which leads to disordered cellular metabolic patterns and cell death. In particular, in an I/R injury model, cancer cells, and adipocytes, MCU expression is maintained at high levels. As is well accepted, the AMPK/PGC-1α/SIRT3 pathway is believed to have an affinity for mROS formation and energy consumption. Therefore, we identified a link between MCU-related mROS formation and the AMPK/PGC-1α/SIRT3 signaling pathway in controlling cell metabolism and cell death, which may provide a new possibility of targeting the MCU to reverse relevant diseases.
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Affiliation(s)
- Yuxin Wang
- Department of Orthopaedic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiang Li
- Department of Orthopaedic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fengchao Zhao
- Department of Orthopaedic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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26
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Pallafacchina G, Zanin S, Rizzuto R. From the Identification to the Dissection of the Physiological Role of the Mitochondrial Calcium Uniporter: An Ongoing Story. Biomolecules 2021; 11:biom11060786. [PMID: 34071006 PMCID: PMC8224590 DOI: 10.3390/biom11060786] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/14/2021] [Accepted: 05/20/2021] [Indexed: 12/16/2022] Open
Abstract
The notion of mitochondria being involved in the decoding and shaping of intracellular Ca2+ signals has been circulating since the end of the 19th century. Despite that, the molecular identity of the channel that mediates Ca2+ ion transport into mitochondria remained elusive for several years. Only in the last decade, the genes and pathways responsible for the mitochondrial uptake of Ca2+ began to be cloned and characterized. The gene coding for the pore-forming unit of the mitochondrial channel was discovered exactly 10 years ago, and its product was called mitochondrial Ca2+ uniporter or MCU. Before that, only one of its regulators, the mitochondria Ca2+ uptake regulator 1, MICU1, has been described in 2010. However, in the following years, the scientific interest in mitochondrial Ca2+ signaling regulation and physiological role has increased. This shortly led to the identification of many of its components, to the description of their 3D structure, and the characterization of the uniporter contribution to tissue physiology and pathology. In this review, we will summarize the most relevant achievements in the history of mitochondrial Ca2+ studies, presenting a chronological overview of the most relevant and landmarking discoveries. Finally, we will explore the impact of mitochondrial Ca2+ signaling in the context of muscle physiology, highlighting the recent advances in understanding the role of the MCU complex in the control of muscle trophism and metabolism.
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Affiliation(s)
- Giorgia Pallafacchina
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
- Neuroscience Institute, Italian National Research Council (CNR), 35131 Padua, Italy
- Correspondence: (G.P.); (R.R.); Tel.: +39-049-827-6029 (G.P.); +39-049-827-3001 (R.R.)
| | - Sofia Zanin
- Department of Immunology, Infectiology and Haematology, Institut Necker-Enfants Malades (INEM), INSERM U1151-CNRS UMR 8253, 75015 Paris, France;
| | - Rosario Rizzuto
- Neuroscience Institute, Italian National Research Council (CNR), 35131 Padua, Italy
- Correspondence: (G.P.); (R.R.); Tel.: +39-049-827-6029 (G.P.); +39-049-827-3001 (R.R.)
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27
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Gherardi G, De Mario A, Mammucari C. The mitochondrial calcium homeostasis orchestra plays its symphony: Skeletal muscle is the guest of honor. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:209-259. [PMID: 34253296 DOI: 10.1016/bs.ircmb.2021.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Skeletal muscle mitochondria are placed in close proximity of the sarcoplasmic reticulum (SR), the main intracellular Ca2+ store. During muscle activity, excitation of sarcolemma and of T-tubule triggers the release of Ca2+ from the SR initiating myofiber contraction. The rise in cytosolic Ca2+ determines the opening of the mitochondrial calcium uniporter (MCU), the highly selective channel of the inner mitochondrial membrane (IMM), causing a robust increase in mitochondrial Ca2+ uptake. The Ca2+-dependent activation of TCA cycle enzymes increases the synthesis of ATP required for SERCA activity. Thus, Ca2+ is transported back into the SR and cytosolic [Ca2+] returns to resting levels eventually leading to muscle relaxation. In recent years, thanks to the molecular identification of MCU complex components, the role of mitochondrial Ca2+ uptake in the pathophysiology of skeletal muscle has been uncovered. In this chapter, we will introduce the reader to a general overview of mitochondrial Ca2+ accumulation. We will tackle the key molecular players and the cellular and pathophysiological consequences of mitochondrial Ca2+ dyshomeostasis. In the second part of the chapter, we will discuss novel findings on the physiological role of mitochondrial Ca2+ uptake in skeletal muscle. Finally, we will examine the involvement of mitochondrial Ca2+ signaling in muscle diseases.
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Affiliation(s)
- Gaia Gherardi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Agnese De Mario
- Department of Biomedical Sciences, University of Padua, Padua, Italy
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28
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Bitarafan F, Khodaeian M, Amjadi Sardehaei E, Darvishi FZ, Almadani N, Nilipour Y, Garshasbi M. Identification of a novel MICU1 nonsense variant causes myopathy with extrapyramidal signs in an Iranian consanguineous family. Mol Cell Pediatr 2021; 8:6. [PMID: 33969448 PMCID: PMC8107061 DOI: 10.1186/s40348-021-00116-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 04/14/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ca2+ as a universal second messenger regulates basic biological functions including cell cycle, cell proliferation, cell differentiation, and cell death. Lack of the protein mitochondrial calcium uptake1 (MICU1), which has been regarded as a gatekeeper of Ca ions, leads to the abnormal mitochondrial Ca2+ handling, excessive production of reactive oxygen species (ROS), and increased cell death. Mutations in MICU1 gene causes a very rare neuromuscular disease, myopathy with extrapyramidal signs (MPXPS), due to primary alterations in mitochondrial calcium signaling which demonstrates the key role of mitochondrial Ca2+ uptake. To date, 13 variants have been reported in MICU1 gene in 44 patients presented with the vast spectrum of symptoms. CASE PRESENTATION Here, we report a 44-year-old Iranian patient presented with learning disability, muscle weakness, easy fatigability, reduced tendon reflexes, ataxia, gait disturbance, elevated hepatic transaminases, elevated serum creatine kinase (CK), and elevated lactate dehydrogenase (LDH). We identified a novel nonsense variant c.385C>T; p.(R129*) in MICU1 gene by whole exome sequencing (WES) and segregation analysis. CONCLUSIONS Our finding along with previous studies provides more evidence on the clinical presentation of the disease caused by pathogenic mutations in MICU1. Finding more variants and expanding the spectrum of the disease increases the diagnostic rate of molecular testing in screening of this kind of diseases and in turn improves the quality of counseling for at risk couples and helps them to minimize the risks of having affected children.
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Affiliation(s)
- Fatemeh Bitarafan
- Department of Biology, Faculty of Biological Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | | | | | | | - Navid Almadani
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Yalda Nilipour
- Pediatric Pathology Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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29
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Bustos G, Ahumada-Castro U, Silva-Pavez E, Puebla A, Lovy A, Cesar Cardenas J. The ER-mitochondria Ca 2+ signaling in cancer progression: Fueling the monster. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 363:49-121. [PMID: 34392932 DOI: 10.1016/bs.ircmb.2021.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cancer is a leading cause of death worldwide. All major tumor suppressors and oncogenes are now recognized to have fundamental connections with metabolic pathways. A hallmark feature of cancer cells is a reprogramming of their metabolism even when nutrients are available. Increasing evidence indicates that most cancer cells rely on mitochondrial metabolism to sustain their energetic and biosynthetic demands. Mitochondria are functionally and physically coupled to the endoplasmic reticulum (ER), the major calcium (Ca2+) storage organelle in mammalian cells, through special domains known as mitochondria-ER contact sites (MERCS). In this domain, the release of Ca2+ from the ER is mainly regulated by inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs), a family of Ca2+ release channels activated by the ligand IP3. IP3R mediated Ca2+ release is transferred to mitochondria through the mitochondrial Ca2+ uniporter (MCU). Once in the mitochondrial matrix, Ca2+ activates several proteins that stimulate mitochondrial performance. The role of IP3R and MCU in cancer, as well as the other proteins that enable the Ca2+ communication between these two organelles is just beginning to be understood. Here, we describe the function of the main players of the ER mitochondrial Ca2+ communication and discuss how this particular signal may contribute to the rise and development of cancer traits.
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Affiliation(s)
- Galdo Bustos
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Ulises Ahumada-Castro
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Eduardo Silva-Pavez
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Andrea Puebla
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Alenka Lovy
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile; Department of Neuroscience, Center for Neuroscience Research, Tufts School of Medicine, Boston, MA, United States.
| | - J Cesar Cardenas
- Faculty of Sciences, Universidad Mayor, Center for Integrative Biology, Santiago, Chile; Geroscience Center for Brain Health and Metabolism, Santiago, Chile; Buck Institute for Research on Aging, Novato, CA, United States; Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States.
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30
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Zhao H, Pan X. Mitochondrial Ca 2+ and cell cycle regulation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:171-207. [PMID: 34253295 DOI: 10.1016/bs.ircmb.2021.02.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It has been demonstrated for more than 40 years that intracellular calcium (Ca2+) controls a variety of cellular functions, including mitochondrial metabolism and cell proliferation. Cytosolic Ca2+ fluctuation during key stages of the cell cycle can lead to mitochondrial Ca2+ uptake and subsequent activation of mitochondrial oxidative phosphorylation and a range of signaling. However, the relationship between mitochondrial Ca2+ and cell cycle progression has long been neglected because the molecule responsible for Ca2+ uptake has been unknown. Recently, the identification of the mitochondrial Ca2+ uniporter (MCU) has led to key advances. With improved Ca2+ imaging and detection, effects of MCU-mediated mitochondrial Ca2+ have been observed at different stages of the cell cycle. Elevated Ca2+ signaling boosts ATP and ROS production, remodels cytosolic Ca2+ pathways and reprograms cell fate-determining networks. These findings suggest that manipulating mitochondrial Ca2+ signaling may serve as a potential strategy in the control of many crucial biological events, such as tumor development and cell division in hematopoietic stem cells (HSCs). In this review, we summarize the current understanding of the role of mitochondrial Ca2+ signaling during different stages of the cell cycle and highlight the potential physiological and pathological significance of mitochondrial Ca2+ signaling.
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Affiliation(s)
- Haixin Zhao
- State Key Laboratory of Experimental Haematology, Institute of Hematology, Fifth Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Xin Pan
- State Key Laboratory of Proteomics, Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing, China.
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31
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Guo L. Mitochondria and the permeability transition pore in cancer metabolic reprogramming. Biochem Pharmacol 2021; 188:114537. [PMID: 33811907 DOI: 10.1016/j.bcp.2021.114537] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 02/07/2023]
Abstract
Mitochondria are a major source of ATP provision as well as cellular suicidal weapon store. Accumulating evidences demonstrate that mitochondrial bioenergetics, biosynthesis and signaling are important mediators of tumorigenesis. Metabolic plasticity enables cancer cell reprogramming to cope with cellular and environmental alterations, a process requires mitochondria biology. Mitochondrial metabolism emerges to be a promising arena for cancer therapeutic targets. The permeability transition pore (PTP) participates in physiological Ca2+ and ROS homeostasis as well as cell death depending on the open state. The hypothesis that PTP forms from F-ATP synthase provides clues to the potential collaborative role of mitochondrial respiration and PTP in regulating cancer cell fate and metabolic reprogramming.
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Affiliation(s)
- Lishu Guo
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200072, China.
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32
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Alevriadou BR, Patel A, Noble M, Ghosh S, Gohil VM, Stathopulos PB, Madesh M. Molecular nature and physiological role of the mitochondrial calcium uniporter channel. Am J Physiol Cell Physiol 2021; 320:C465-C482. [PMID: 33296287 PMCID: PMC8260355 DOI: 10.1152/ajpcell.00502.2020] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Calcium (Ca2+) signaling is critical for cell function and cell survival. Mitochondria play a major role in regulating the intracellular Ca2+ concentration ([Ca2+]i). Mitochondrial Ca2+ uptake is an important determinant of cell fate and governs respiration, mitophagy/autophagy, and the mitochondrial pathway of apoptosis. Mitochondrial Ca2+ uptake occurs via the mitochondrial Ca2+ uniporter (MCU) complex. This review summarizes the present knowledge on the function of MCU complex, regulation of MCU channel, and the role of MCU in Ca2+ homeostasis and human disease pathogenesis. The channel core consists of four MCU subunits and essential MCU regulators (EMRE). Regulatory proteins that interact with them include mitochondrial Ca2+ uptake 1/2 (MICU1/2), MCU dominant-negative β-subunit (MCUb), MCU regulator 1 (MCUR1), and solute carrier 25A23 (SLC25A23). In addition to these proteins, cardiolipin, a mitochondrial membrane-specific phospholipid, has been shown to interact with the channel core. The dynamic interplay between the core and regulatory proteins modulates MCU channel activity after sensing local changes in [Ca2+]i, reactive oxygen species, and other environmental factors. Here, we highlight the structural details of the human MCU heteromeric assemblies and their known roles in regulating mitochondrial Ca2+ homeostasis. MCU dysfunction has been shown to alter mitochondrial Ca2+ dynamics, in turn eliciting cell apoptosis. Changes in mitochondrial Ca2+ uptake have been implicated in pathological conditions affecting multiple organs, including the heart, skeletal muscle, and brain. However, our structural and functional knowledge of this vital protein complex remains incomplete, and understanding the precise role for MCU-mediated mitochondrial Ca2+ signaling in disease requires further research efforts.
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Affiliation(s)
- B Rita Alevriadou
- Department of Biomedical Engineering, Jacobs School of Medicine and Biomedical Sciences and School of Engineering and Applied Sciences, University at Buffalo-State University of New York, Buffalo, New York
| | - Akshar Patel
- Department of Biomedical Engineering, Jacobs School of Medicine and Biomedical Sciences and School of Engineering and Applied Sciences, University at Buffalo-State University of New York, Buffalo, New York
| | - Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Sagnika Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Muniswamy Madesh
- Department of Medicine/Cardiology Division, Center for Precision Medicine, University of Texas Health San Antonio, San Antonio, Texas
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Cividini F, Scott BT, Suarez J, Casteel DE, Heinz S, Dai A, Diemer T, Suarez JA, Benner CW, Ghassemian M, Dillmann WH. Ncor2/PPARα-Dependent Upregulation of MCUb in the Type 2 Diabetic Heart Impacts Cardiac Metabolic Flexibility and Function. Diabetes 2021; 70:665-679. [PMID: 33303689 PMCID: PMC7897348 DOI: 10.2337/db20-0779] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/27/2020] [Indexed: 12/14/2022]
Abstract
The contribution of altered mitochondrial Ca2+ handling to metabolic and functional defects in type 2 diabetic (T2D) mouse hearts is not well understood. In this study, we show that the T2D heart is metabolically inflexible and almost exclusively dependent on mitochondrial fatty acid oxidation as a consequence of mitochondrial calcium uniporter complex (MCUC) inhibitory subunit MCUb overexpression. Using a recombinant endonuclease-deficient Cas9-based gene promoter pulldown approach coupled with mass spectrometry, we found that MCUb is upregulated in the T2D heart due to loss of glucose homeostasis regulator nuclear receptor corepressor 2 repression, and chromatin immunoprecipitation assays identified peroxisome proliferator-activated receptor α as a mediator of MCUb gene expression in T2D cardiomyocytes. Upregulation of MCUb limits mitochondrial matrix Ca2+ uptake and impairs mitochondrial energy production via glucose oxidation by depressing pyruvate dehydrogenase complex activity. Gene therapy displacement of endogenous MCUb with a dominant-negative MCUb transgene (MCUbW246R/V251E) in vivo rescued T2D cardiomyocytes from metabolic inflexibility and stimulated cardiac contractile function and adrenergic responsiveness by enhancing phospholamban phosphorylation via protein kinase A. We conclude that MCUb represents one newly discovered molecular effector at the interface of metabolism and cardiac function, and its repression improves the outcome of the chronically stressed diabetic heart.
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Affiliation(s)
- Federico Cividini
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Brian T Scott
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Jorge Suarez
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Darren E Casteel
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Sven Heinz
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Anzhi Dai
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Tanja Diemer
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Jorge A Suarez
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | | | - Majid Ghassemian
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA
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34
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Tanwar J, Singh JB, Motiani RK. Molecular machinery regulating mitochondrial calcium levels: The nuts and bolts of mitochondrial calcium dynamics. Mitochondrion 2021; 57:9-22. [PMID: 33316420 PMCID: PMC7610953 DOI: 10.1016/j.mito.2020.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/18/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Mitochondria play vital role in regulating the cellular energetics and metabolism. Further, it is a signaling hub for cell survival and apoptotic pathways. One of the key determinants that calibrate both cellular energetics and survival functions is mitochondrial calcium (Ca2+) dynamics. Mitochondrial Ca2+ regulates three Ca2+-sensitive dehydrogenase enzymes involved in tricarboxylic acid cycle (TCA) cycle thereby directly controlling ATP synthesis. On the other hand, excessive Ca2+ concentration within the mitochondrial matrix elevates mitochondrial reactive oxygen species (mROS) levels and causes mitochondrial membrane depolarization. This leads to opening of the mitochondrial permeability transition pore (mPTP) and release of cytochrome c into cytosol eventually triggering apoptosis. Therefore, it is critical for cell to maintain mitochondrial Ca2+ concentration. Since cells can neither synthesize nor metabolize Ca2+, it is the dynamic interplay of Ca2+ handling proteins involved in mitochondrial Ca2+ influx and efflux that take the center stage. In this review we would discuss the key molecular machinery regulating mitochondrial Ca2+ concentration. We would focus on the channel complex involved in bringing Ca2+ into mitochondrial matrix i.e. Mitochondrial Ca2+ Uniporter (MCU) and its key regulators Mitochondrial Ca2+ Uptake proteins (MICU1, 2 and 3), MCU regulatory subunit b (MCUb), Essential MCU Regulator (EMRE) and Mitochondrial Ca2+ Uniporter Regulator 1 (MCUR1). Further, we would deliberate on major mitochondrial Ca2+ efflux proteins i.e. Mitochondrial Na+/Ca2+/Li+ exchanger (NCLX) and Leucine zipper EF hand-containing transmembrane1 (Letm1). Moreover, we would highlight the physiological functions of these proteins and discuss their relevance in human pathophysiology. Finally, we would highlight key outstanding questions in the field.
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Affiliation(s)
- Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi 10025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Jaya Bharti Singh
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India
| | - Rajender K Motiani
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India.
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35
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Boyman L, Greiser M, Lederer WJ. Calcium influx through the mitochondrial calcium uniporter holocomplex, MCU cx. J Mol Cell Cardiol 2021; 151:145-154. [PMID: 33147447 PMCID: PMC7880866 DOI: 10.1016/j.yjmcc.2020.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/20/2020] [Accepted: 10/28/2020] [Indexed: 12/11/2022]
Abstract
Ca2+ flux into the mitochondrial matrix through the MCU holocomplex (MCUcx) has recently been measured quantitatively and with milliseconds resolution for the first time under physiological conditions in both heart and skeletal muscle. Additionally, the dynamic levels of Ca2+ in the mitochondrial matrix ([Ca2+]m) of cardiomyocytes were measured as it was controlled by the balance between influx of Ca2+ into the mitochondrial matrix through MCUcx and efflux through the mitochondrial Na+ / Ca2+ exchanger (NCLX). Under these conditions [Ca2+]m was shown to regulate ATP production by the mitochondria at only a few critical sites. Additional functions attributed to [Ca2+]m continue to be reported in the literature. Here we review the new findings attributed to MCUcx function and provide a framework for understanding and investigating mitochondrial Ca2+ influx features, many of which remain controversial. The properties and functions of the MCUcx subunits that constitute the holocomplex are challenging to tease apart. Such distinct subunits include EMRE, MCUR1, MICUx (i.e. MICU1, MICU2, MICU3), and the pore-forming subunits (MCUpore). Currently, the specific set of functions of each subunit remains non-quantitative and controversial. The more contentious issues are discussed in the context of the newly measured native MCUcx Ca2+ flux from heart and skeletal muscle. These MCUcx Ca2+ flux measurements have been shown to be a highly-regulated, tissue-specific with femto-Siemens Ca2+ conductances and with distinct extramitochondrial Ca2+ ([Ca2+]i) dependencies. These data from cardiac and skeletal muscle mitochondria have been examined quantitatively for their threshold [Ca2+]i levels and for hypothesized gatekeeping function and are discussed in the context of model cell (e.g. HeLa, MEF, HEK293, COS7 cells) measurements. Our new findings on MCUcx dependent matrix [Ca2+]m signaling provide a quantitative basis for on-going and new investigations of the roles of MCUcx in cardiac function ranging from metabolic fuel selection, capillary blood-flow control and the pathological activation of the mitochondrial permeability transition pore (mPTP). Additionally, this review presents the use of advanced new methods that can be readily adapted by any investigator to enable them to carry out quantitative Ca2+ measurements in mitochondria while controlling the inner mitochondrial membrane potential, ΔΨm.
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Affiliation(s)
- Liron Boyman
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; The Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Maura Greiser
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; The Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; The Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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36
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Kumar VK, Lackey A, Snyder J, Karhadkar S, Rao AD, DiCarlo A, Sato PY. Mitochondrial Membrane Intracellular Communication in Healthy and Diseased Myocardium. Front Cell Dev Biol 2020; 8:609241. [PMID: 33425917 PMCID: PMC7786191 DOI: 10.3389/fcell.2020.609241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/19/2020] [Indexed: 12/24/2022] Open
Abstract
Research efforts in the twenty-first century have been paramount to the discovery and development of novel pharmacological treatments in a variety of diseases resulting in improved life expectancy. Yet, cardiac disease remains a leading cause of morbidity and mortality worldwide. Over time, there has been an expansion in conditions such as atrial fibrillation (AF) and heart failure (HF). Although past research has elucidated specific pathways that participate in the development of distinct cardiac pathologies, the exact mechanisms of action leading to disease remain to be fully characterized. Protein turnover and cellular bioenergetics are integral components of cardiac diseases, highlighting the importance of mitochondria and endoplasmic reticulum (ER) in driving cellular homeostasis. More specifically, the interactions between mitochondria and ER are crucial to calcium signaling, apoptosis induction, autophagy, and lipid biosynthesis. Here, we summarize mitochondrial and ER functions and physical interactions in healthy physiological states. We then transition to perturbations that occur in response to pathophysiological challenges and how this alters mitochondrial–ER and other intracellular organelle interactions. Finally, we discuss lifestyle interventions and innovative therapeutic targets that may be used to restore beneficial mitochondrial and ER interactions, thereby improving cardiac function.
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Affiliation(s)
- Vishnu K Kumar
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Atreju Lackey
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Jonathan Snyder
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Sunil Karhadkar
- Department of Surgery, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Ajay D Rao
- Section of Endocrinology, Diabetes and Metabolism, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States.,Center for Metabolic Disease Research, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Antonio DiCarlo
- Department of Surgery, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Priscila Y Sato
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
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37
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Jung H, Kim SY, Canbakis Cecen FS, Cho Y, Kwon SK. Dysfunction of Mitochondrial Ca 2+ Regulatory Machineries in Brain Aging and Neurodegenerative Diseases. Front Cell Dev Biol 2020; 8:599792. [PMID: 33392190 PMCID: PMC7775422 DOI: 10.3389/fcell.2020.599792] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/06/2020] [Indexed: 12/20/2022] Open
Abstract
Calcium ions (Ca2+) play critical roles in neuronal processes, such as signaling pathway activation, transcriptional regulation, and synaptic transmission initiation. Therefore, the regulation of Ca2+ homeostasis is one of the most important processes underlying the basic cellular viability and function of the neuron. Multiple components, including intracellular organelles and plasma membrane Ca2+-ATPase, are involved in neuronal Ca2+ control, and recent studies have focused on investigating the roles of mitochondria in synaptic function. Numerous mitochondrial Ca2+ regulatory proteins have been identified in the past decade, with studies demonstrating the tissue- or cell-type-specific function of each component. The mitochondrial calcium uniporter and its binding subunits are major inner mitochondrial membrane proteins contributing to mitochondrial Ca2+ uptake, whereas the mitochondrial Na+/Ca2+ exchanger (NCLX) and mitochondrial permeability transition pore (mPTP) are well-studied proteins involved in Ca2+ extrusion. The level of cytosolic Ca2+ and the resulting characteristics of synaptic vesicle release properties are controlled via mitochondrial Ca2+ uptake and release at presynaptic sites, while in dendrites, mitochondrial Ca2+ regulation affects synaptic plasticity. During brain aging and the progress of neurodegenerative disease, mitochondrial Ca2+ mishandling has been observed using various techniques, including live imaging of Ca2+ dynamics. Furthermore, Ca2+ dysregulation not only disrupts synaptic transmission but also causes neuronal cell death. Therefore, understanding the detailed pathophysiological mechanisms affecting the recently discovered mitochondrial Ca2+ regulatory machineries will help to identify novel therapeutic targets. Here, we discuss current research into mitochondrial Ca2+ regulatory machineries and how mitochondrial Ca2+ dysregulation contributes to brain aging and neurodegenerative disease.
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Affiliation(s)
- Hyunsu Jung
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea.,Division of Life Sciences, Korea University, Seoul, South Korea
| | - Su Yeon Kim
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea.,Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea
| | - Fatma Sema Canbakis Cecen
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul, South Korea
| | - Yongcheol Cho
- Division of Life Sciences, Korea University, Seoul, South Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul, South Korea
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38
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Genovese I, Vezzani B, Danese A, Modesti L, Vitto VAM, Corazzi V, Pelucchi S, Pinton P, Giorgi C. Mitochondria as the decision makers for cancer cell fate: from signaling pathways to therapeutic strategies. Cell Calcium 2020; 92:102308. [PMID: 33096320 DOI: 10.1016/j.ceca.2020.102308] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023]
Abstract
As pivotal players in cellular metabolism, mitochondria have a double-faceted role in the final decision of cell fate. This is true for all cell types, but it is even more important and intriguing in the cancer setting. Mitochondria regulate cell fate in many diverse ways: through metabolism, by producing ATP and other metabolites deemed vital or detrimental for cancer cells; through the regulation of Ca2+ homeostasis, especially by the joint participation of the endoplasmic reticulum in a membranous tethering system for Ca2+ signaling called mitochondria-ER associated membranes (MAMs); and by regulating signaling pathways involved in the survival of cancer cells such as mitophagy. Recent studies have shown that mitochondria can also play a role in the regulation of inflammatory pathways in cancer cells, for example, through the release of mitochondrial DNA (mtDNA) involved in the activation of the cGAS-cGAMP-STING pathway. In this review, we aim to explore the role of mitochondria as decision makers in fostering cancer cell death or survival depending on the tumor cell stage and describe novel anticancer therapeutic strategies targeting mitochondria.
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Affiliation(s)
- Ilaria Genovese
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Bianca Vezzani
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Alberto Danese
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Lorenzo Modesti
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Veronica Angela Maria Vitto
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Virginia Corazzi
- ENT & Audiology Department, University Hospital of Ferrara, Ferrara, Italy
| | - Stefano Pelucchi
- ENT & Audiology Department, University Hospital of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Carlotta Giorgi
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy.
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Gherardi G, Monticelli H, Rizzuto R, Mammucari C. The Mitochondrial Ca 2+ Uptake and the Fine-Tuning of Aerobic Metabolism. Front Physiol 2020; 11:554904. [PMID: 33117189 PMCID: PMC7575740 DOI: 10.3389/fphys.2020.554904] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 09/14/2020] [Indexed: 12/13/2022] Open
Abstract
Recently, the role of mitochondrial activity in high-energy demand organs and in the orchestration of whole-body metabolism has received renewed attention. In mitochondria, pyruvate oxidation, ensured by efficient mitochondrial pyruvate entry and matrix dehydrogenases activity, generates acetyl CoA that enters the TCA cycle. TCA cycle activity, in turn, provides reducing equivalents and electrons that feed the electron transport chain eventually producing ATP. Mitochondrial Ca2+ uptake plays an essential role in the control of aerobic metabolism. Mitochondrial Ca2+ accumulation stimulates aerobic metabolism by inducing the activity of three TCA cycle dehydrogenases. In detail, matrix Ca2+ indirectly modulates pyruvate dehydrogenase via pyruvate dehydrogenase phosphatase 1, and directly activates isocitrate and α-ketoglutarate dehydrogenases. Here, we will discuss the contribution of mitochondrial Ca2+ uptake to the metabolic homeostasis of organs involved in systemic metabolism, including liver, skeletal muscle, and adipose tissue. We will also tackle the role of mitochondrial Ca2+ uptake in the heart, a high-energy consuming organ whose function strictly depends on appropriate Ca2+ signaling.
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Affiliation(s)
- Gaia Gherardi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy
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40
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MacEwen MJ, Markhard AL, Bozbeyoglu M, Bradford F, Goldberger O, Mootha VK, Sancak Y. Evolutionary divergence reveals the molecular basis of EMRE dependence of the human MCU. Life Sci Alliance 2020; 3:e202000718. [PMID: 32769116 PMCID: PMC7425227 DOI: 10.26508/lsa.202000718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 01/18/2023] Open
Abstract
The mitochondrial calcium uniporter (MCU) is a calcium-activated calcium channel critical for signaling and bioenergetics. MCU, the pore-forming subunit of the uniporter, contains two transmembrane domains and is found in all major eukaryotic taxa. In amoeba and fungi, MCU homologs are sufficient to form a functional calcium channel, whereas human MCU exhibits a strict requirement for the metazoan protein essential MCU regulator (EMRE) for conductance. Here, we exploit this evolutionary divergence to decipher the molecular basis of human MCU's dependence on EMRE. By systematically generating chimeric proteins that consist of EMRE-independent Dictyostelium discoideum MCU and Homo sapiens MCU (HsMCU), we converged on a stretch of 10 amino acids in D. discoideum MCU that can be transplanted to HsMCU to render it EMRE independent. We call this region in human MCU the EMRE dependence domain (EDD). Crosslinking experiments show that EMRE directly interacts with HsMCU at its transmembrane domains as well as the EDD. Our results suggest that EMRE stabilizes the EDD of MCU, permitting both channel opening and calcium conductance, consistent with recently published structures of MCU-EMRE.
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Affiliation(s)
| | - Andrew L Markhard
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Mert Bozbeyoglu
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | - Forrest Bradford
- Department of Pharmacology, University of Washington, Seattle, WA, USA
| | - Olga Goldberger
- 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
- Broad Institute, Cambridge, MA, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Yasemin Sancak
- Department of Pharmacology, University of Washington, Seattle, WA, USA
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41
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Diaz-Juarez J, Suarez JA, Dillmann WH, Suarez J. Mitochondrial calcium handling and heart disease in diabetes mellitus. Biochim Biophys Acta Mol Basis Dis 2020; 1867:165984. [PMID: 33002576 DOI: 10.1016/j.bbadis.2020.165984] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 01/23/2023]
Abstract
Diabetes mellitus-induced heart disease, including diabetic cardiomyopathy, is an important medical problem and is difficult to treat. Diabetes mellitus increases the risk for heart failure and decreases cardiac myocyte function, which are linked to changes in cardiac mitochondrial energy metabolism. The free mitochondrial calcium concentration ([Ca2+]m) is fundamental in activating the mitochondrial respiratory chain complexes and ATP production and is also known to regulate the activity of key mitochondrial dehydrogenases. The mitochondrial calcium uniporter complex (MCUC) plays a major role in mediating mitochondrial Ca2+ import, and its expression and function therefore may have a marked impact on cardiac myocyte metabolism and function. Here, we summarize the pathophysiological role of [Ca2+]m handling and MCUC in the diabetic heart. In addition, we evaluate potential therapeutic targets, directed to the machinery that regulates mitochondrial calcium handling, to alleviate diabetes-related cardiac disease.
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Affiliation(s)
- Julieta Diaz-Juarez
- Department of Pharmacology, Instituto Nacional de Cardiología, Juan Badiano No. 1, Col. Seccion XVI, 14080 Tlalpan, Ciudad de Mexico, Mexico
| | - Jorge A Suarez
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Wolfgang H Dillmann
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jorge Suarez
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
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Natarajan V, Mah T, Peishi C, Tan SY, Chawla R, Arumugam TV, Ramasamy A, Mallilankaraman K. Oxygen Glucose Deprivation Induced Prosurvival Autophagy Is Insufficient to Rescue Endothelial Function. Front Physiol 2020; 11:533683. [PMID: 33041854 PMCID: PMC7526687 DOI: 10.3389/fphys.2020.533683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 08/12/2020] [Indexed: 12/19/2022] Open
Abstract
Endothelial dysfunction, referring to a disturbance in the vascular homeostasis, has been implicated in many disease conditions including ischemic/reperfusion injury and atherosclerosis. Endothelial mitochondria have been increasingly recognized as a regulator of calcium homeostasis which has implications in the execution of diverse cellular events and energy production. The mitochondrial calcium uniporter complex through which calcium enters the mitochondria is composed of several proteins, including the pore-forming subunit MCU and its regulators MCUR1, MICU1, and MICU2. Mitochondrial calcium overload leads to opening of MPTP (mitochondrial permeability transition pore) and results in apoptotic cell death. Whereas, blockage of calcium entry into the mitochondria results in reduced ATP production thereby activates AMPK-mediated pro-survival autophagy. Here, we investigated the expression of mitochondrial calcium uniporter complex components (MCU, MCUR1, MICU1, and MICU2), induction of autophagy and apoptotic cell death in endothelial cells in response to oxygen-glucose deprivation. Human pulmonary microvascular endothelial cells (HPMVECs) were subjected to oxygen-glucose deprivation (OGD) at 3-h timepoints up to 12 h. Interestingly, except MCUR1 which was significantly downregulated, all other components of the uniporter (MCU, MICU1, and MICU2) remained unchanged. MCUR1 downregulation has been shown to activate AMPK mediated pro-survival autophagy. Similarly, MCUR1 downregulation in response to OGD resulted in AMPK phosphorylation and LC3 processing indicating the activation of pro-survival autophagy. Despite the activation of autophagy, OGD induced Caspase-mediated apoptotic cell death. Blockade of autophagy did not reduce OGD-induced apoptotic cell death whereas serum starvation conferred enough cellular and functional protection. In conclusion, the autophagic flux induced by MCUR1 downregulation in response to OGD is insufficient in protecting endothelial cells from undergoing apoptotic cell death and requires enhancement of autophagic flux by additional means such as serum starvation.
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Affiliation(s)
- Venkateswaran Natarajan
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tania Mah
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Chen Peishi
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Shu Yi Tan
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Ritu Chawla
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Thiruma Valavan Arumugam
- Department of Physiology, Anatomy and Microbiology School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| | | | - Karthik Mallilankaraman
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Center for Healthy Longevity, NUHS, Singapore, Singapore
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Vais H, Payne R, Paudel U, Li C, Foskett JK. Coupled transmembrane mechanisms control MCU-mediated mitochondrial Ca 2+ uptake. Proc Natl Acad Sci U S A 2020; 117:21731-21739. [PMID: 32801213 PMCID: PMC7474680 DOI: 10.1073/pnas.2005976117] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ca2+ uptake by mitochondria regulates bioenergetics, apoptosis, and Ca2+ signaling. The primary pathway for mitochondrial Ca2+ uptake is the mitochondrial calcium uniporter (MCU), a Ca2+-selective ion channel in the inner mitochondrial membrane. MCU-mediated Ca2+ uptake is driven by the sizable inner-membrane potential generated by the electron-transport chain. Despite the large thermodynamic driving force, mitochondrial Ca2+ uptake is tightly regulated to maintain low matrix [Ca2+] and prevent opening of the permeability transition pore and cell death, while meeting dynamic cellular energy demands. How this is accomplished is controversial. Here we define a regulatory mechanism of MCU-channel activity in which cytoplasmic Ca2+ regulation of intermembrane space-localized MICU1/2 is controlled by Ca2+-regulatory mechanisms localized across the membrane in the mitochondrial matrix. Ca2+ that permeates through the channel pore regulates Ca2+ affinities of coupled inhibitory and activating sensors in the matrix. Ca2+ binding to the inhibitory sensor within the MCU amino terminus closes the channel despite Ca2+ binding to MICU1/2. Conversely, disruption of the interaction of MICU1/2 with the MCU complex disables matrix Ca2+ regulation of channel activity. Our results demonstrate how Ca2+ influx into mitochondria is tuned by coupled Ca2+-regulatory mechanisms on both sides of the inner mitochondrial membrane.
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Affiliation(s)
- Horia Vais
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Riley Payne
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Usha Paudel
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Carmen Li
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104;
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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Shah SI, Ullah G. The Function of Mitochondrial Calcium Uniporter at the Whole-Cell and Single Mitochondrion Levels in WT, MICU1 KO, and MICU2 KO Cells. Cells 2020; 9:E1520. [PMID: 32580385 PMCID: PMC7349584 DOI: 10.3390/cells9061520] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]M) uptake through its Ca2+ uniporter (MCU) is central to many cell functions such as bioenergetics, spatiotemporal organization of Ca2+ signals, and apoptosis. MCU activity is regulated by several intrinsic proteins including MICU1, MICU2, and EMRE. While significant details about the role of MICU1, MICU2, and EMRE in MCU function have emerged recently, a key challenge for the future experiments is to investigate how these regulatory proteins modulate mitochondrial Ca2+ influx through MCU in intact cells under pathophysiological conditions. This is further complicated by the fact that several variables affecting MCU function change dynamically as cell functions. To overcome this void, we develop a data-driven model that closely replicates the behavior of MCU under a wide range of cytosolic Ca2+ ([Ca2+]C), [Ca2+]M, and mitochondrial membrane potential values in WT, MICU1 knockout (KO), and MICU2 KO cells at the single mitochondrion and whole-cell levels. The model is extended to investigate how MICU1 or MICU2 KO affect mitochondrial function. Moreover, we show how Ca2+ buffering proteins, the separation between mitochondrion and Ca2+-releasing stores, and the duration of opening of Ca2+-releasing channels affect mitochondrial function under different conditions. Finally, we demonstrate an easy extension of the model to single channel function of MCU.
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Affiliation(s)
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33647, USA;
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Liu JC. Is MCU dispensable for normal heart function? J Mol Cell Cardiol 2020; 143:175-183. [DOI: 10.1016/j.yjmcc.2020.04.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/07/2020] [Accepted: 04/24/2020] [Indexed: 12/14/2022]
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Noble M, Lin QT, Sirko C, Houpt JA, Novello MJ, Stathopulos PB. Structural Mechanisms of Store-Operated and Mitochondrial Calcium Regulation: Initiation Points for Drug Discovery. Int J Mol Sci 2020; 21:E3642. [PMID: 32455637 PMCID: PMC7279490 DOI: 10.3390/ijms21103642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/11/2020] [Accepted: 05/17/2020] [Indexed: 12/18/2022] Open
Abstract
Calcium (Ca2+) is a universal signaling ion that is essential for the life and death processes of all eukaryotes. In humans, numerous cell stimulation pathways lead to the mobilization of sarco/endoplasmic reticulum (S/ER) stored Ca2+, resulting in the propagation of Ca2+ signals through the activation of processes, such as store-operated Ca2+ entry (SOCE). SOCE provides a sustained Ca2+ entry into the cytosol; moreover, the uptake of SOCE-mediated Ca2+ by mitochondria can shape cytosolic Ca2+ signals, function as a feedback signal for the SOCE molecular machinery, and drive numerous mitochondrial processes, including adenosine triphosphate (ATP) production and distinct cell death pathways. In recent years, tremendous progress has been made in identifying the proteins mediating these signaling pathways and elucidating molecular structures, invaluable for understanding the underlying mechanisms of function. Nevertheless, there remains a disconnect between using this accumulating protein structural knowledge and the design of new research tools and therapies. In this review, we provide an overview of the Ca2+ signaling pathways that are involved in mediating S/ER stored Ca2+ release, SOCE, and mitochondrial Ca2+ uptake, as well as pinpoint multiple levels of crosstalk between these pathways. Further, we highlight the significant protein structures elucidated in recent years controlling these Ca2+ signaling pathways. Finally, we describe a simple strategy that aimed at applying the protein structural data to initiating drug design.
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Affiliation(s)
- Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Qi-Tong Lin
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Christian Sirko
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Jacob A. Houpt
- Department of Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada;
| | - Matthew J. Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
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Roman B, Kaur P, Ashok D, Kohr M, Biswas R, O'Rourke B, Steenbergen C, Das S. Nuclear-mitochondrial communication involving miR-181c plays an important role in cardiac dysfunction during obesity. J Mol Cell Cardiol 2020; 144:87-96. [PMID: 32442661 DOI: 10.1016/j.yjmcc.2020.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/09/2020] [Accepted: 05/16/2020] [Indexed: 12/26/2022]
Abstract
AIMS In cardiomyocytes, there is microRNA (miR) in the mitochondria that originates from the nuclear genome and matures in the cytoplasm before translocating into the mitochondria. Overexpression of one such miR, miR-181c, can lead to heart failure by stimulating reactive oxygen species (ROS) production and increasing mitochondrial calcium level ([Ca2+]m). Mitochondrial calcium uptake 1 protein (MICU1), a regulatory protein in the mitochondrial calcium uniporter complex, plays an important role in regulating [Ca2+]m. Obesity results in miR-181c overexpression and a decrease in MICU1. We hypothesize that lowering miR-181c would protect against obesity-induced cardiac dysfunction. METHODS AND RESULTS We used an in vivo mouse model of high-fat diet (HFD) for 18 weeks and induced high lipid load in H9c2 cells with oleate-conjugated bovine serum albumin in vitro. We tested the cardioprotective role of lowering miR-181c by using miR-181c/d-/- mice (in vivo) and AntagomiR against miR-181c (in vitro). HFD significantly upregulated heart levels of miR-181c and led to cardiac hypertrophy in wild-type mice, but not in miR-181c/d-/- mice. HFD also increased ROS production and pyruvate dehydrogenase activity (a surrogate for [Ca2+]m), but the increases were alleviated in miR-181c/d-/- mice. Moreover, miR-181c/d-/- mice fed a HFD had higher levels of MICU1 than did wild-type mice fed a HFD, attenuating the rise in [Ca2+]m. Overexpression of miR-181c in neonatal ventricular cardiomyocytes (NMVM) caused increased ROS production, which oxidized transcription factor Sp1 and led to a loss of Sp1, thereby slowing MICU1 transcription. Hence, miR-181c increases [Ca2+]m through Sp1 oxidation and downregulation of MICU1, suggesting that the cardioprotective effect of miR-181c/d-/- results from inhibition of Sp1 oxidation. CONCLUSION This study has identified a unique nuclear-mitochondrial communication mechanism in the heart orchestrated by miR-181c. Obesity-induced overexpression of miR-181c increases [Ca2+]m via downregulation of MICU1 and leads to cardiac injury. A strategy to inhibit miR-181c in cardiomyocytes can preserve cardiac function during obesity by improving mitochondrial function. Altering miR-181c expression may provide a pharmacologic approach to improve cardiomyopathy in individuals with obesity/type 2 diabetes.
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Affiliation(s)
- Barbara Roman
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - Pawandeep Kaur
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - Deepthi Ashok
- Division of Cardiology, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - Mark Kohr
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Roopa Biswas
- Department of Anatomy, Physiology and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - Charles Steenbergen
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America.
| | - Samarjit Das
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America; Department of Anesthesiology & Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States of America.
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48
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Plotegher N, Perocheau D, Ferrazza R, Massaro G, Bhosale G, Zambon F, Rahim AA, Guella G, Waddington SN, Szabadkai G, Duchen MR. Impaired cellular bioenergetics caused by GBA1 depletion sensitizes neurons to calcium overload. Cell Death Differ 2020; 27:1588-1603. [PMID: 31685979 PMCID: PMC7206133 DOI: 10.1038/s41418-019-0442-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 12/19/2022] Open
Abstract
Heterozygous mutations of the lysosomal enzyme glucocerebrosidase (GBA1) represent the major genetic risk for Parkinson's disease (PD), while homozygous GBA1 mutations cause Gaucher disease, a lysosomal storage disorder, which may involve severe neurodegeneration. We have previously demonstrated impaired autophagy and proteasomal degradation pathways and mitochondrial dysfunction in neurons from GBA1 knockout (gba1-/-) mice. We now show that stimulation with physiological glutamate concentrations causes pathological [Ca2+]c responses and delayed calcium deregulation, collapse of mitochondrial membrane potential and an irreversible fall in the ATP/ADP ratio. Mitochondrial Ca2+ uptake was reduced in gba1-/- cells as was expression of the mitochondrial calcium uniporter. The rate of free radical generation was increased in gba1-/- neurons. Behavior of gba1+/- neurons was similar to gba1-/- in terms of all variables, consistent with a contribution of these mechanisms to the pathogenesis of PD. These data signpost reduced bioenergetic capacity and [Ca2+]c dysregulation as mechanisms driving neurodegeneration.
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Affiliation(s)
- Nicoletta Plotegher
- Cell and Developmental Biology Department, University College London, London, WC1E6XA, UK
- Department of Biology, University of Padua, 35131, Padua, Italy
| | - Dany Perocheau
- Institute for Women's Health, University College London, London, WC1E6HU, UK
| | - Ruggero Ferrazza
- Department of Physics, University of Trento, 38123, Povo (TN), Italy
| | - Giulia Massaro
- School of Pharmacy, University College London, London, WC1N1AX, UK
| | - Gauri Bhosale
- Cell and Developmental Biology Department, University College London, London, WC1E6XA, UK
| | - Federico Zambon
- Cell and Developmental Biology Department, University College London, London, WC1E6XA, UK
| | - Ahad A Rahim
- School of Pharmacy, University College London, London, WC1N1AX, UK
| | - Graziano Guella
- Department of Physics, University of Trento, 38123, Povo (TN), Italy
| | - Simon N Waddington
- Institute for Women's Health, University College London, London, WC1E6HU, UK
- MRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Gyorgy Szabadkai
- Cell and Developmental Biology Department, University College London, London, WC1E6XA, UK
- Department of Biomedical Sciences, University of Padua, 35131, Padua, Italy
- The Francis Crick Institute, London, NW1 1AT, UK
| | - Michael R Duchen
- Cell and Developmental Biology Department, University College London, London, WC1E6XA, UK.
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Payne R, Li C, Foskett JK. Variable Assembly of EMRE and MCU Creates Functional Channels with Distinct Gatekeeping Profiles. iScience 2020; 23:101037. [PMID: 32315830 PMCID: PMC7170992 DOI: 10.1016/j.isci.2020.101037] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 02/24/2020] [Accepted: 04/01/2020] [Indexed: 10/29/2022] Open
Abstract
MCU is a Ca2+-selective channel that mediates mitochondrial Ca2+ influx. The human channel contains tetrameric pore-forming MCU, regulatory subunits MICU1/2, and EMRE that is required both for channel function and MICU1/2-mediated Ca2+ regulation. A structure of MCU with EMRE revealed a 4:4 stoichiometry, but the stoichiometry in vivo is unknown. Expression of tagged EMRE and MCU at a 1:10 ratio in cells lacking EMRE and MCU restored channel activity but not full channel gatekeeping. Increasing EMRE expression enhanced gatekeeping, raising the cytoplasmic Ca2+ concentration ([Ca2+]c) threshold for channel activation. MCU-EMRE concatemers creating channels with 1EMRE:4MCU restored Ca2+ uptake in cells, whereas cells expressing concatemers that enforced a 4EMRE:4MCU stoichiometry demonstrated enhanced channel gatekeeping. Concatemers enforcing 2EMRE/4MCU recapitulated the activity, gatekeeping, and size of endogenous channels. Thus, MCU does not require four EMRE, with most endogenous channels containing two, but complexes with 1-4 EMRE have activity with full or partial gatekeeping.
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Affiliation(s)
- Riley Payne
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Carmen Li
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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50
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Ponnalagu D, Singh H. Insights Into the Role of Mitochondrial Ion Channels in Inflammatory Response. Front Physiol 2020; 11:258. [PMID: 32327997 PMCID: PMC7160495 DOI: 10.3389/fphys.2020.00258] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/05/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are the source of many pro-inflammatory signals that cause the activation of the immune system and generate inflammatory responses. They are also potential targets of pro-inflammatory mediators, thus triggering a severe inflammatory response cycle. As mitochondria are a central hub for immune system activation, their dysfunction leads to many inflammatory disorders. Thus, strategies aiming at regulating mitochondrial dysfunction can be utilized as a therapeutic tool to cure inflammatory disorders. Two key factors that determine the structural and functional integrity of mitochondria are mitochondrial ion channels and transporters. They are not only important for maintaining the ionic homeostasis of the cell, but also play a role in regulating reactive oxygen species generation, ATP production, calcium homeostasis and apoptosis, which are common pro-inflammatory signals. The significance of the mitochondrial ion channels in inflammatory response is still not clearly understood and will need further investigation. In this article, we review the different mechanisms by which mitochondria can generate the inflammatory response as well as highlight how mitochondrial ion channels modulate these mechanisms and impact the inflammatory processes.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, United States
| | - Harpreet Singh
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, United States
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