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Balderas E, Lee SHJ, Rai NK, Mollinedo DM, Duron HE, Chaudhuri D. Mitochondrial Calcium Regulation of Cardiac Metabolism in Health and Disease. Physiology (Bethesda) 2024; 39:0. [PMID: 38713090 DOI: 10.1152/physiol.00014.2024] [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: 02/29/2024] [Revised: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 05/08/2024] Open
Abstract
Oxidative phosphorylation is regulated by mitochondrial calcium (Ca2+) in health and disease. In physiological states, Ca2+ enters via the mitochondrial Ca2+ uniporter and rapidly enhances NADH and ATP production. However, maintaining Ca2+ homeostasis is critical: insufficient Ca2+ impairs stress adaptation, and Ca2+ overload can trigger cell death. In this review, we delve into recent insights further defining the relationship between mitochondrial Ca2+ dynamics and oxidative phosphorylation. Our focus is on how such regulation affects cardiac function in health and disease, including heart failure, ischemia-reperfusion, arrhythmias, catecholaminergic polymorphic ventricular tachycardia, mitochondrial cardiomyopathies, Barth syndrome, and Friedreich's ataxia. Several themes emerge from recent data. First, mitochondrial Ca2+ regulation is critical for fuel substrate selection, metabolite import, and matching of ATP supply to demand. Second, mitochondrial Ca2+ regulates both the production and response to reactive oxygen species (ROS), and the balance between its pro- and antioxidant effects is key to how it contributes to physiological and pathological states. Third, Ca2+ exerts localized effects on the electron transport chain (ETC), not through traditional allosteric mechanisms but rather indirectly. These effects hinge on specific transporters, such as the uniporter or the Na+/Ca2+ exchanger, and may not be noticeable acutely, contributing differently to phenotypes depending on whether Ca2+ transporters are acutely or chronically modified. Perturbations in these novel relationships during disease states may either serve as compensatory mechanisms or exacerbate impairments in oxidative phosphorylation. Consequently, targeting mitochondrial Ca2+ holds promise as a therapeutic strategy for a variety of cardiac diseases characterized by contractile failure or arrhythmias.
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Affiliation(s)
- Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Sandra H J Lee
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Neeraj K Rai
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - David M Mollinedo
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Hannah E Duron
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, Biochemistry, Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States
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Amjid U, Aziz U, Habib U, Jabeen I. Biological regulatory network analysis for targeting the mitochondrial calcium uniporter (MCU) mediated calcium (Ca 2+) transport in neurodegenerative disorders. Cell Biochem Funct 2024; 42:e4082. [PMID: 38944766 DOI: 10.1002/cbf.4082] [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: 04/02/2024] [Revised: 05/30/2024] [Accepted: 06/18/2024] [Indexed: 07/01/2024]
Abstract
Calcium (Ca2+) has been observed as the most important ion involved in a series of cellular processes and its homeostasis is critical for normal cellular functions. Mitochondrial calcium uniporter (MCU) complex has been recognized as the most important calcium-specific channel located in the inner mitochondrial membrane and is one of the major players in maintaining the Ca2+ homeostasis by transporting Ca2+ across the mitochondrial membrane. Furthermore, dysregulation of the mitochondrial Ca2+ homeostasis has been orchestrated to neurodegenerative response. This necessitates quantitative evaluation of the MCU-dependent mROS production and subsequent cellular responses for more specific therapeutic interventions against neurodegenerative disorders. Towards this goal, here we present a biological regulatory network of MCU to dynamically simulate the MCU-mediated ROS production and its response in neurodegeneration. Previously, ruthenium complex RuRed and its derivatives have been reported to show low nM to high µM potency against MCU to maintain cytosolic Ca2+ (cCa2+) homeostasis by modulating mitochondrial Ca2+ (mCa2+) uptake. Therefore, structural modeling and dynamic simulation of MCU pore-forming subunit is performed to probe the interaction profiling of previously reported Ru265 and its derivatives compounds with MCU. The current study highlighted MCU as a potential drug target in neurodegenerative disorders. Furthermore, ASP261 and GLU264 amino acid residues in DIME motif of MCU pore-forming subunits are identified as crucial for modulating the activity of MCU in neurodegenerative disorders.
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Affiliation(s)
- Umar Amjid
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Sciences & Technology (NUST), Islamabad, Pakistan
- Department of Paediatrics and Child Health, Medical College, Aga Khan University Hospital, Karachi, Pakistan
| | - Ubair Aziz
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Sciences & Technology (NUST), Islamabad, Pakistan
| | - Uzma Habib
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Sciences & Technology (NUST), Islamabad, Pakistan
| | - Ishrat Jabeen
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Sciences & Technology (NUST), Islamabad, Pakistan
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3
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Colussi DM, Stathopulos PB. The mitochondrial calcium uniporter: Balancing tumourigenic and anti-tumourigenic responses. J Physiol 2024; 602:3315-3339. [PMID: 38857425 DOI: 10.1113/jp285515] [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: 12/26/2023] [Accepted: 05/20/2024] [Indexed: 06/12/2024] Open
Abstract
Increased malignancy and poor treatability associated with solid tumour cancers have commonly been attributed to mitochondrial calcium (Ca2+) dysregulation. The mitochondrial Ca2+ uniporter complex (mtCU) is the predominant mode of Ca2+ uptake into the mitochondrial matrix. The main components of mtCU are the pore-forming mitochondrial Ca2+ uniporter (MCU) subunit, MCU dominant-negative beta (MCUb) subunit, essential MCU regulator (EMRE) and the gatekeeping mitochondrial Ca2+ uptake 1 and 2 (MICU1 and MICU2) proteins. In this review, we describe mtCU-mediated mitochondrial Ca2+ dysregulation in solid tumour cancer types, finding enhanced mtCU activity observed in colorectal cancer, breast cancer, oral squamous cell carcinoma, pancreatic cancer, hepatocellular carcinoma and embryonal rhabdomyosarcoma. By contrast, decreased mtCU activity is associated with melanoma, whereas the nature of mtCU dysregulation remains unclear in glioblastoma. Furthermore, we show that numerous polymorphisms associated with cancer may alter phosphorylation sites on the pore forming MCU and MCUb subunits, which cluster at interfaces with EMRE. We highlight downstream/upstream biomolecular modulators of MCU and MCUb that alter mtCU-mediated mitochondrial Ca2+ uptake and may be used as biomarkers or to aid in the development of novel cancer therapeutics. Additionally, we provide an overview of the current small molecule inhibitors of mtCU that interact with the Asp residue of the critical Asp-Ile-Met-Glu motif or through other allosteric regulatory mechanisms to block Ca2+ permeation. Finally, we describe the relationship between MCU- and MCUb-mediating microRNAs and mitochondrial Ca2+ uptake that should be considered in the discovery of new treatment approaches for cancer.
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Affiliation(s)
- Danielle M Colussi
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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Noble M, Colussi DM, Junop M, Stathopulos PB. The MCU and MCUb amino-terminal domains tightly interact: mechanisms for low conductance assembly of the mitochondrial calcium uniporter complex. iScience 2024; 27:109699. [PMID: 38706857 PMCID: PMC11068563 DOI: 10.1016/j.isci.2024.109699] [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: 08/28/2023] [Revised: 02/12/2024] [Accepted: 04/05/2024] [Indexed: 05/07/2024] Open
Abstract
The mitochondrial calcium (Ca2+) uniporter (MCU) complex is regulated via integration of the MCU dominant negative beta subunit (MCUb), a low conductance paralog of the main MCU pore forming protein. The MCU amino (N)-terminal domain (NTD) also modulates channel function through cation binding to the MCU regulating acidic patch (MRAP). MCU and MCUb have high sequence similarities, yet the structural and functional roles of MCUb-NTD remain unknown. Here, we report that MCUb-NTD exhibits α-helix/β-sheet structure with a high thermal stability, dependent on protein concentration. Remarkably, MCU- and MCUb-NTDs heteromerically interact with ∼nM affinity, increasing secondary structure and stability and structurally perturbing MRAP. Further, we demonstrate MCU and MCUb co-localization is suppressed upon NTD deletion concomitant with increased mitochondrial Ca2+ uptake. Collectively, our data show that MCU:MCUb NTD tight interactions are promoted by enhanced regular structure and stability, augmenting MCU:MCUb co-localization, lowering mitochondrial Ca2+ uptake and implicating an MRAP-sensing mechanism.
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Affiliation(s)
- Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A5C1, Canada
| | - Danielle M. Colussi
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A5C1, Canada
| | - Murray Junop
- Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A5C1, Canada
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A5C1, Canada
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Fuentes JM, Morcillo P. The Role of Cardiolipin in Mitochondrial Function and Neurodegenerative Diseases. Cells 2024; 13:609. [PMID: 38607048 PMCID: PMC11012098 DOI: 10.3390/cells13070609] [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: 02/18/2024] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/13/2024] Open
Abstract
Cardiolipin (CL) is a mitochondria-exclusive phospholipid synthesized in the inner mitochondrial membrane. CL plays a key role in mitochondrial membranes, impacting a plethora of functions this organelle performs. Consequently, it is conceivable that abnormalities in the CL content, composition, and level of oxidation may negatively impact mitochondrial function and dynamics, with important implications in a variety of diseases. This review concentrates on papers published in recent years, combined with basic and underexplored research in CL. We capture new findings on its biological functions in the mitochondria, as well as its association with neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Lastly, we explore the potential applications of CL as a biomarker and pharmacological target to mitigate mitochondrial dysfunction.
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Affiliation(s)
- José M. Fuentes
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Enfermería y Terapia Ocupacional, Universidad de Extremadura, 10003 Cáceres, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, Instituto de Salud Carlos III (CIBER-CIBERNED-ISCIII), 28029 Madrid, Spain
- Instituto Universitario de Investigación Biosanitaria de Extremadura (INUBE), 10003 Cáceres, Spain
| | - Patricia Morcillo
- Departmentof Neurology, Columbia University, New York, NY 10032, USA
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Gutiérrez-Mireles ER, Páez-Franco JC, Rodríguez-Ruíz R, Germán-Acacio JM, López-Aquino MC, Gutiérrez-Aguilar M. An Arabidopsis mutant line lacking the mitochondrial calcium transport regulator MICU shows an altered metabolite profile. PLANT SIGNALING & BEHAVIOR 2023; 18:2271799. [PMID: 37879964 PMCID: PMC10601504 DOI: 10.1080/15592324.2023.2271799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/12/2023] [Indexed: 10/27/2023]
Abstract
Plant metabolism is constantly changing and requires input signals for efficient regulation. The mitochondrial calcium uniporter (MCU) couples organellar and cytoplasmic calcium oscillations leading to oxidative metabolism regulation in a vast array of species. In Arabidopsis thaliana, genetic deletion of AtMICU leads to altered mitochondrial calcium handling and ultrastructure. Here we aimed to further assess the consequences upon genetic deletion of AtMICU. Our results confirm that AtMICU safeguards intracellular calcium transport associated with carbohydrate, amino acid, and phytol metabolism modifications. The implications of such alterations are discussed.
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Affiliation(s)
- Emilia R. Gutiérrez-Mireles
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - José Carlos Páez-Franco
- Red de Apoyo a la Investigación, Coordinación de la Investigación Científica-UNAM, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Ciudad de México, México
| | - Raúl Rodríguez-Ruíz
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Juan Manuel Germán-Acacio
- Red de Apoyo a la Investigación, Coordinación de la Investigación Científica-UNAM, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Ciudad de México, México
| | - M. Casandra López-Aquino
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Manuel Gutiérrez-Aguilar
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, México
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Joshi A, Gohil VM. Cardiolipin deficiency leads to the destabilization of mitochondrial magnesium channel MRS2 in Barth syndrome. Hum Mol Genet 2023; 32:3353-3360. [PMID: 37721533 DOI: 10.1093/hmg/ddad153] [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: 07/17/2023] [Revised: 09/10/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023] Open
Abstract
Barth syndrome (BTHS) is a debilitating X-linked cardio-skeletal myopathy caused by loss-of-function mutations in TAFAZZIN, a cardiolipin (CL)-remodeling enzyme required for the maintenance of normal levels of CL species in mitochondrial membranes. At present, how perturbations in CL abundance and composition lead to many debilitating clinical presentations in BTHS patients have not been fully elucidated. Inspired by our recent findings that CL is essential for optimal mitochondrial calcium uptake, we measured the levels of other biologically important metal ions in BTHS mitochondria and found that in addition to calcium, magnesium levels are significantly reduced. Consistent with this observation, we report a decreased abundance of the mitochondrial magnesium influx channel MRS2 in multiple models of BTHS including yeast, murine myoblast, and BTHS patient cells and cardiac tissue. Mechanistically, we attribute reduced steady-state levels of MRS2 to its increased turnover in CL-deficient BTHS models. By expressing Mrs2 in well-characterized yeast mutants of the phospholipid biosynthetic pathways, we demonstrate a specific requirement of CL for Mrs2 abundance and assembly. Finally, we provide in vitro evidence for the direct binding of CL with human MRS2. Together, our study has identified a critical requirement of CL for MRS2 stability and suggests perturbation of mitochondrial magnesium homeostasis as a novel contributing factor to BTHS pathology.
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Affiliation(s)
- Alaumy Joshi
- Department of Biochemistry and Biophysics, Texas A&M University, 301 Old Main Drive, TAMU 3474, College Station, TX 77843, United States
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, 301 Old Main Drive, TAMU 3474, College Station, TX 77843, United States
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Trewin AJ, Weeks KL, Wadley GD, Lamon S. Regulation of mitochondrial calcium uniporter expression and calcium-dependent cell signaling by lncRNA Tug1 in cardiomyocytes. Am J Physiol Cell Physiol 2023; 325:C1097-C1105. [PMID: 37721002 DOI: 10.1152/ajpcell.00339.2023] [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: 07/26/2023] [Revised: 09/08/2023] [Accepted: 09/08/2023] [Indexed: 09/19/2023]
Abstract
Cardiomyocyte calcium homeostasis is a tightly regulated process. The mitochondrial calcium uniporter (MCU) complex can buffer elevated cytosolic Ca2+ levels and consists of pore-forming proteins including MCU, and various regulatory proteins such as mitochondrial calcium uptake proteins 1 and 2 (MICU1/2). The stoichiometry of these proteins influences the sensitivity to Ca2+ and the activity of the complex. However, the factors that regulate their gene expression remain incompletely understood. Long noncoding RNAs (lncRNAs) regulate gene expression through various mechanisms, and we recently found that the lncRNA Tug1 increased the expression of Mcu and associated genes. To further explore this, we performed antisense LNA knockdown of Tug1 (Tug1 KD) in H9c2 rat cardiomyocytes. Tug1 KD increased MCU protein expression, yet pyruvate dehydrogenase dephosphorylation, which is indicative of mitochondrial Ca2+ uptake, was not enhanced. However, RNA-seq revealed that Tug1 KD increased Mcu along with differential expression of >1,000 genes including many related to Ca2+ regulation pathways in the heart. To understand the effect of this on Ca2+ signaling, we measured phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and its downstream target cAMP Response Element-Binding protein (CREB), a transcription factor known to drive Mcu gene expression. In response to a Ca2+ stimulus, the increase in CaMKII and CREB phosphorylation was attenuated by Tug1 KD. Inhibition of CaMKII, but not CREB, partially prevented the Tug1 KD-mediated increase in Mcu. Together, these data suggest that Tug1 modulates MCU expression via a mechanism involving CaMKII and regulates cardiomyocyte Ca2+ signaling, which could have important implications for cardiac function.NEW & NOTEWORTHY Calcium is essential for signaling, excitation contraction, and energy homeostasis in the heart. Despite this, molecular regulators of these processes are not completely understood. We report that knockdown of lncRNA Tug1 alters the calcium handling transcriptome and increases mitochondrial calcium uniporter expression via a mechanism involving CaMKII. As overexpression of MCU is known to be protective against pathological cardiac remodeling, targeting Tug1 may be a potential strategy for treating cardiovascular disease.
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Affiliation(s)
- Adam J Trewin
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Kate L Weeks
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Glenn D Wadley
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
| | - Séverine Lamon
- School of Exercise and Nutrition Sciences, Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, Australia
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Dridi H, Santulli G, Bahlouli L, Miotto MC, Weninger G, Marks AR. Mitochondrial Calcium Overload Plays a Causal Role in Oxidative Stress in the Failing Heart. Biomolecules 2023; 13:1409. [PMID: 37759809 PMCID: PMC10527470 DOI: 10.3390/biom13091409] [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: 08/17/2023] [Revised: 09/13/2023] [Accepted: 09/17/2023] [Indexed: 09/29/2023] Open
Abstract
Heart failure is a serious global health challenge, affecting more than 6.2 million people in the United States and is projected to reach over 8 million by 2030. Independent of etiology, failing hearts share common features, including defective calcium (Ca2+) handling, mitochondrial Ca2+ overload, and oxidative stress. In cardiomyocytes, Ca2+ not only regulates excitation-contraction coupling, but also mitochondrial metabolism and oxidative stress signaling, thereby controlling the function and actual destiny of the cell. Understanding the mechanisms of mitochondrial Ca2+ uptake and the molecular pathways involved in the regulation of increased mitochondrial Ca2+ influx is an ongoing challenge in order to identify novel therapeutic targets to alleviate the burden of heart failure. In this review, we discuss the mechanisms underlying altered mitochondrial Ca2+ handling in heart failure and the potential therapeutic strategies.
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Affiliation(s)
- Haikel Dridi
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians & Surgeons, New York, NY 10032, USA; (L.B.); (M.C.M.); (G.W.); (A.R.M.)
| | - Gaetano Santulli
- Department of Medicine, Division of Cardiology, Wilf Family Cardiovascular Research Institute, Albert Einstein College of Medicine, New York, NY 10461, USA;
| | - Laith Bahlouli
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians & Surgeons, New York, NY 10032, USA; (L.B.); (M.C.M.); (G.W.); (A.R.M.)
| | - Marco C. Miotto
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians & Surgeons, New York, NY 10032, USA; (L.B.); (M.C.M.); (G.W.); (A.R.M.)
| | - Gunnar Weninger
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians & Surgeons, New York, NY 10032, USA; (L.B.); (M.C.M.); (G.W.); (A.R.M.)
| | - Andrew R. Marks
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians & Surgeons, New York, NY 10032, USA; (L.B.); (M.C.M.); (G.W.); (A.R.M.)
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Joshi A, Richard TH, Gohil VM. Mitochondrial phospholipid metabolism in health and disease. J Cell Sci 2023; 136:jcs260857. [PMID: 37655851 PMCID: PMC10482392 DOI: 10.1242/jcs.260857] [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] [Indexed: 09/02/2023] Open
Abstract
Studies of rare human genetic disorders of mitochondrial phospholipid metabolism have highlighted the crucial role that membrane phospholipids play in mitochondrial bioenergetics and human health. The phospholipid composition of mitochondrial membranes is highly conserved from yeast to humans, with each class of phospholipid performing a specific function in the assembly and activity of various mitochondrial membrane proteins, including the oxidative phosphorylation complexes. Recent studies have uncovered novel roles of cardiolipin and phosphatidylethanolamine, two crucial mitochondrial phospholipids, in organismal physiology. Studies on inter-organellar and intramitochondrial phospholipid transport have significantly advanced our understanding of the mechanisms that maintain mitochondrial phospholipid homeostasis. Here, we discuss these recent advances in the function and transport of mitochondrial phospholipids while describing their biochemical and biophysical properties and biosynthetic pathways. Additionally, we highlight the roles of mitochondrial phospholipids in human health by describing the various genetic diseases caused by disruptions in their biosynthesis and discuss advances in therapeutic strategies for Barth syndrome, the best-studied disorder of mitochondrial phospholipid metabolism.
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Affiliation(s)
- Alaumy Joshi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Travis H. Richard
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Vishal M. Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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11
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Kumari A, Nguyen DM, Garg V. Patch-clamp technique to study mitochondrial membrane biophysics. J Gen Physiol 2023; 155:e202313347. [PMID: 37347216 PMCID: PMC10287547 DOI: 10.1085/jgp.202313347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/12/2023] [Accepted: 06/08/2023] [Indexed: 06/23/2023] Open
Abstract
Mitochondria are double-membrane organelles crucial for oxidative phosphorylation, enabling efficient ATP synthesis by eukaryotic cells. Both of the membranes, the highly selective inner mitochondrial membrane (IMM) and a relatively porous outer membrane (OMM), harbor a number of integral membrane proteins that help in the transport of biological molecules. These transporters are especially enriched in the IMM, where they help maintain transmembrane gradients for H+, K+, Ca2+, PO43-, and metabolites like ADP/ATP, citrate, etc. Impaired activity of these transporters can affect the efficiency of energy-transducing processes and can alter cellular redox state, leading to activation of cell-death pathways or metabolic syndromes in vivo. Although several methodologies are available to study ion flux through membrane proteins, the patch-clamp technique remains the gold standard for quantitatively analyzing electrogenic ion exchange across membranes. Direct patch-clamp recordings of mitoplasts (mitochondria devoid of outer membrane) in different modes, such as whole-mitoplast or excised-patch mode, allow researchers the opportunity to study the biophysics of mitochondrial transporters in the native membrane, in real time, in isolation from other fluxes or confounding factors due to changes in ion gradients, pH, or mitochondrial potential (ΔΨ). Here, we summarize the use of patch clamp to investigate several membrane proteins of mitochondria. We demonstrate how this technique can be reliably applied to record whole-mitoplast Ca2+ currents mediated via mitochondrial calcium uniporter or H+ currents mediated by uncoupling protein 1 and discuss critical considerations while recording currents from these small vesicles of the IMM (mitoplast diameter = 2-5 µm).
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Affiliation(s)
- Anshu Kumari
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Dung M. Nguyen
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Vivek Garg
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
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Novorolsky RJ, Kasheke GDS, Hakim A, Foldvari M, Dorighello GG, Sekler I, Vuligonda V, Sanders ME, Renden RB, Wilson JJ, Robertson GS. Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery. Front Cell Neurosci 2023; 17:1226630. [PMID: 37484823 PMCID: PMC10360135 DOI: 10.3389/fncel.2023.1226630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.
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Affiliation(s)
- Robyn J. Novorolsky
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Gracious D. S. Kasheke
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Antoine Hakim
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Marianna Foldvari
- School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel G. Dorighello
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben Gurion University, Beersheva, Israel
| | | | | | - Robert B. Renden
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, College of Arts and Sciences, Cornell University, Ithaca, NY, United States
| | - George S. Robertson
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Brain Repair Centre, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
- Department of Psychiatry, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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13
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Chan C, Yuan CC, McCoy JG, Ward PS, Grabarek Z. The mitochondrial calcium uniporter transports Ca 2+ via a ligand-relay mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.17.545435. [PMID: 37398228 PMCID: PMC10312793 DOI: 10.1101/2023.06.17.545435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The mitochondrial calcium uniporter (mtCU) is a multicomponent Ca 2+ -specific channel that imparts mitochondria with the capacity to sense the cytosolic calcium signals. The metazoan mtCU comprises the pore-forming subunit MCU and the essential regulator EMRE, arranged in a tetrameric channel complex, and the Ca 2+ sensing peripheral proteins MICU1-3. The mechanism of mitochondrial Ca 2+ uptake by mtCU and its regulation is poorly understood. Our analysis of MCU structure and sequence conservation, combined with molecular dynamics simulations, mutagenesis, and functional studies, led us to conclude that the Ca 2+ conductance of MCU is driven by a ligand-relay mechanism, which depends on stochastic structural fluctuations in the conserved DxxE sequence. In the tetrameric structure of MCU, the four glutamate side chains of DxxE (the E-ring) chelate Ca 2+ directly in a high-affinity complex (site 1), which blocks the channel. The four glutamates can also switch to a hydrogen bond-mediated interaction with an incoming hydrated Ca 2+ transiently sequestered within the D-ring of DxxE (site 2), thus releasing the Ca 2+ bound at site 1. This process depends critically on the structural flexibility of DxxE imparted by the adjacent invariant Pro residue. Our results suggest that the activity of the uniporter can be regulated through the modulation of local structural dynamics. A preliminary account of this work was presented at the 67 th Annual Meeting of the Biophysical Society in San Diego, CA, February 18-22, 2023.
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14
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De Mario A, D'Angelo D, Zanotti G, Raffaello A, Mammucari C. The mitochondrial calcium uniporter complex–A play in five acts. Cell Calcium 2023; 112:102720. [PMID: 37001308 DOI: 10.1016/j.ceca.2023.102720] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023]
Abstract
Mitochondrial Ca2+ (mitCa2+) uptake controls both intraorganellar and cytosolic functions. Within the organelle, [Ca2+] increases regulate the activity of tricarboxylic acid (TCA) cycle enzymes, thus sustaining oxidative metabolism and ATP production. Reactive oxygen species (ROS) are also generated as side products of oxygen consumption. At the same time, mitochondria act as buffers of cytosolic Ca2+ (cytCa2+) increases, thus regulating Ca2+-dependent cellular processes. In pathological conditions, mitCa2+ overload triggers the opening of the mitochondrial permeability transition pore (mPTP) and the release of apoptotic cofactors. MitCa2+ uptake occurs in response of local [Ca2+] increases in sites of proximity between the endoplasmic reticulum (ER) and the mitochondria and is mediated by the mitochondrial Ca2+ uniporter (MCU), a highly selective channel of the inner mitochondrial membrane (IMM). Both channel and regulatory subunits form the MCU complex (MCUC). Cryogenic electron microscopy (Cryo-EM) and crystal structures revealed the correct assembly of MCUC and the function of critical residues for the regulation of Ca2+ conductance.
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15
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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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16
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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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17
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MacEwen MJ, Sancak Y. Beyond the matrix: structural and physiological advancements in mitochondrial calcium signaling. Biochem Soc Trans 2023; 51:665-673. [PMID: 36960768 PMCID: PMC10212541 DOI: 10.1042/bst20220317] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/25/2023]
Abstract
Mitochondrial calcium (Ca2+) signaling has long been known to regulate diverse cellular functions, ranging from ATP production via oxidative phosphorylation, to cytoplasmic Ca2+ signaling to apoptosis. Central to mitochondrial Ca2+ signaling is the mitochondrial Ca2+ uniporter complex (MCUC) which enables Ca2+ flux from the cytosol into the mitochondrial matrix. Several pivotal discoveries over the past 15 years have clarified the identity of the proteins comprising MCUC. Here, we provide an overview of the literature on mitochondrial Ca2+ biology and highlight recent findings on the high-resolution structure, dynamic regulation, and new functions of MCUC, with an emphasis on publications from the last five years. We discuss the importance of these findings for human health and the therapeutic potential of targeting mitochondrial Ca2+ signaling.
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Affiliation(s)
| | - Yasemin Sancak
- Department of Pharmacology, University of Washington, Seattle, WA 98195, U.S.A
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18
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De Nicolo B, Cataldi-Stagetti E, Diquigiovanni C, Bonora E. Calcium and Reactive Oxygen Species Signaling Interplays in Cardiac Physiology and Pathologies. Antioxidants (Basel) 2023; 12:antiox12020353. [PMID: 36829912 PMCID: PMC9952851 DOI: 10.3390/antiox12020353] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
Mitochondria are key players in energy production, critical activity for the smooth functioning of energy-demanding organs such as the muscles, brain, and heart. Therefore, dysregulation or alterations in mitochondrial bioenergetics primarily perturb these organs. Within the cell, mitochondria are the major site of reactive oxygen species (ROS) production through the activity of different enzymes since it is one of the organelles with the major availability of oxygen. ROS can act as signaling molecules in a number of different pathways by modulating calcium (Ca2+) signaling. Interactions among ROS and calcium signaling can be considered bidirectional, with ROS regulating cellular Ca2+ signaling, whereas Ca2+ signaling is essential for ROS production. In particular, we will discuss how alterations in the crosstalk between ROS and Ca2+ can lead to mitochondrial bioenergetics dysfunctions and the consequent damage to tissues at high energy demand, such as the heart. Changes in Ca2+ can induce mitochondrial alterations associated with reduced ATP production and increased production of ROS. These changes in Ca2+ levels and ROS generation completely paralyze cardiac contractility. Thus, ROS can hinder the excitation-contraction coupling, inducing arrhythmias, hypertrophy, apoptosis, or necrosis of cardiac cells. These interplays in the cardiovascular system are the focus of this review.
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Affiliation(s)
- Bianca De Nicolo
- Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
| | - Erica Cataldi-Stagetti
- Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
| | - Chiara Diquigiovanni
- Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
- Correspondence: ; Tel.: +39-051209476
| | - Elena Bonora
- Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
- Medical Genetics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy
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19
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Colussi DM, Stathopulos PB. From passage to inhibition: Uncovering the structural and physiological inhibitory mechanisms of MCUb in mitochondrial calcium regulation. FASEB J 2023; 37:e22678. [PMID: 36538269 PMCID: PMC10107711 DOI: 10.1096/fj.202201080r] [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: 07/07/2022] [Revised: 10/14/2022] [Accepted: 11/21/2022] [Indexed: 12/24/2022]
Abstract
Mitochondrial calcium (Ca2+ ) regulation is critically implicated in the regulation of bioenergetics and cell fate. Ca2+ , a universal signaling ion, passively diffuses into the mitochondrial intermembrane space (IMS) through voltage-dependent anion channels (VDAC), where uptake into the matrix is tightly regulated across the inner mitochondrial membrane (IMM) by the mitochondrial Ca2+ uniporter complex (mtCU). In recent years, immense progress has been made in identifying and characterizing distinct structural and physiological mechanisms of mtCU component function. One of the main regulatory components of the Ca2+ selective mtCU channel is the mitochondrial Ca2+ uniporter dominant-negative beta subunit (MCUb). The structural mechanisms underlying the inhibitory effect(s) exerted by MCUb are poorly understood, despite high homology to the main mitochondrial Ca2+ uniporter (MCU) channel-forming subunits. In this review, we provide an overview of the structural differences between MCUb and MCU, believed to contribute to the inhibition of mitochondrial Ca2+ uptake. We highlight the possible structural rationale for the absent interaction between MCUb and the mitochondrial Ca2+ uptake 1 (MICU1) gatekeeping subunit and a potential widening of the pore upon integration of MCUb into the channel. We discuss physiological and pathophysiological information known about MCUb, underscoring implications in cardiac function and arrhythmia as a basis for future therapeutic discovery. Finally, we discuss potential post-translational modifications on MCUb as another layer of important regulation.
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Affiliation(s)
- Danielle M Colussi
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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20
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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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21
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Bigham NP, Huang Z, Spivey J, Woods JJ, MacMillan SN, Wilson JJ. Carboxylate-Capped Analogues of Ru265 Are MCU Inhibitor Prodrugs. Inorg Chem 2022; 61:17299-17312. [PMID: 36260092 DOI: 10.1021/acs.inorgchem.2c02930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The mitochondrial calcium uniporter (MCU) is a transmembrane protein that resides on the inner membrane of the mitochondria and mediates calcium uptake into this organelle. Given the critical role of mitochondrial calcium trafficking in cellular function, inhibitors of this channel have arisen as tools for studying the biological relevance of this process and as potential therapeutic agents. In this study, four new analogues of the previously reported Ru-based MCU inhibitor [ClRu(NH3)4(μ-N)Ru(NH3)4Cl]Cl3 (Ru265) are reported. These compounds, which bear axial carboxylate ligands, are of the general formula [(RCO2)Ru(NH3)4(μ-N)Ru(NH3)4(O2CR)]X3, where X = NO3- or CF3SO3- and R = H (1), CH3 (2), CH2CH3 (3), and (CH2)2CH3 (4). These complexes were fully characterized by IR spectroscopy, NMR spectroscopy, and elemental analysis. X-ray crystal structures of 1 and 3 were obtained, revealing the expected presence of both the linear Ru(μ-N)Ru core and axial formate and propionate ligands. The axial carboxylate ligands of complexes 1-4 are displaced by water in buffered aqueous solution to give the aquated compound Ru265'. The kinetics of these processes were measured by 1H NMR spectroscopy, revealing half-lives that span 5.9-9.9 h at 37 °C. Complex 1 with axial formate ligands underwent aquation approximately twice as fast as the other compounds. In vitro cytotoxicity and mitochondrial membrane potential measurements carried out in HeLa and HEK293T cells demonstrated that none of these four complexes negatively affects cell viability or mitochondrial function. The abilities of 1-4 to inhibit mitochondrial calcium uptake in permeabilized HEK293T cells were assessed and compared to that of Ru265. Fresh solutions of 1-4 are approximately 2-fold less potent than Ru265 with IC50 values in the range of 14.7-19.1 nM. Preincubating 1-4 in aqueous buffers for longer time periods to allow for the aquation reactions to proceed increases their potency of mitochondrial uptake inhibition to match that of Ru265. This result indicates that 1-4 are aquation-activated prodrugs of Ru265'. Finally, 1-4 were shown to inhibit mitochondrial calcium uptake in intact, nonpermeabilized cells, revealing their value as tools and potential therapeutic agents for mitochondrial calcium-related disorders.
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Affiliation(s)
- Nicholas P Bigham
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Zhouyang Huang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Jesse Spivey
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Joshua J Woods
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Robert F. Smith School of Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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22
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Xue K, Wu D, Wang Y, Zhao Y, Shen H, Yao J, Huang X, Li X, Zhou Z, Wang Z, Qiu Y. The mitochondrial calcium uniporter engages UCP1 to form a thermoporter that promotes thermogenesis. Cell Metab 2022; 34:1325-1341.e6. [PMID: 35977541 DOI: 10.1016/j.cmet.2022.07.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 03/03/2022] [Accepted: 07/25/2022] [Indexed: 01/08/2023]
Abstract
Uncoupling protein 1 (UCP1)-mediated adaptive thermogenesis protects mammals against hypothermia and metabolic dysregulation. Whether and how mitochondrial calcium regulates this process remains unclear. Here, we show that mitochondrial calcium uniporter (MCU) recruits UCP1 through essential MCU regulator (EMRE) to form an MCU-EMRE-UCP1 complex upon adrenergic stimulation. This complex formation increases mitochondrial calcium uptake to accelerate the tricarboxylic acid cycle and supply more protons that promote uncoupled respiration, functioning as a thermogenic uniporter. Mitochondrial calcium uptake 1 (MICU1) negatively regulates thermogenesis probably through inhibiting thermogenic uniporter formation. Accordingly, the deletion of Mcu or Emre in brown adipocytes markedly impairs thermogenesis and exacerbates obesity and metabolic dysfunction. Remarkably, the enhanced assembly of the thermogenic uniporter via Micu1 knockout or expressing linked EMRE-UCP1 results in opposite phenotypes. Thus, we have uncovered a "thermoporter" that provides a driving force for the UCP1 operation in thermogenesis, which could be leveraged to combat obesity and associated metabolic disorders.
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Affiliation(s)
- Kaili Xue
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Dongmei Wu
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Yushuang Wang
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Yiheng Zhao
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Hongyu Shen
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Jingfei Yao
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Xun Huang
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xinmeng Li
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Zhao Zhou
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Zihao Wang
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Yifu Qiu
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
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23
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Gottschalk B, Koshenov Z, Waldeck-Weiermair M, Radulović S, Oflaz FE, Hirtl M, Bachkoenig OA, Leitinger G, Malli R, Graier WF. MICU1 controls spatial membrane potential gradients and guides Ca 2+ fluxes within mitochondrial substructures. Commun Biol 2022; 5:649. [PMID: 35778442 PMCID: PMC9249747 DOI: 10.1038/s42003-022-03606-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/17/2022] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial ultrastructure represents a pinnacle of form and function, with the inner mitochondrial membrane (IMM) forming isolated pockets of cristae membrane (CM), separated from the inner-boundary membrane (IBM) by cristae junctions (CJ). Applying structured illumination and electron microscopy, a novel and fundamental function of MICU1 in mediating Ca2+ control over spatial membrane potential gradients (SMPGs) between CM and IMS was identified. We unveiled alterations of SMPGs by transient CJ openings when Ca2+ binds to MICU1 resulting in spatial cristae depolarization. This Ca2+/MICU1-mediated plasticity of the CJ further provides the mechanistic bedrock of the biphasic mitochondrial Ca2+ uptake kinetics via the mitochondrial Ca2+ uniporter (MCU) during intracellular Ca2+ release: Initially, high Ca2+ opens CJ via Ca2+/MICU1 and allows instant Ca2+ uptake across the CM through constantly active MCU. Second, MCU disseminates into the IBM, thus establishing Ca2+ uptake across the IBM that circumvents the CM. Under the condition of MICU1 methylation by PRMT1 in aging or cancer, UCP2 that binds to methylated MICU1 destabilizes CJ, disrupts SMPGs, and facilitates fast Ca2+ uptake via the CM.
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Affiliation(s)
- Benjamin Gottschalk
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Zhanat Koshenov
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Markus Waldeck-Weiermair
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Snježana Radulović
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Furkan E. Oflaz
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Martin Hirtl
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Olaf A. Bachkoenig
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Gerd Leitinger
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Roland Malli
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
| | - Wolfgang F. Graier
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
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Zhang L, Qi J, Zhang X, Zhao X, An P, Luo Y, Luo J. The Regulatory Roles of Mitochondrial Calcium and the Mitochondrial Calcium Uniporter in Tumor Cells. Int J Mol Sci 2022; 23:ijms23126667. [PMID: 35743109 PMCID: PMC9223557 DOI: 10.3390/ijms23126667] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/10/2022] [Accepted: 06/10/2022] [Indexed: 02/06/2023] Open
Abstract
Mitochondria, as the main site of cellular energy metabolism and the generation of oxygen free radicals, are the key switch for mitochondria-mediated endogenous apoptosis. Ca2+ is not only an important messenger for cell proliferation, but it is also an indispensable signal for cell death. Ca2+ participates in and plays a crucial role in the energy metabolism, physiology, and pathology of mitochondria. Mitochondria control the uptake and release of Ca2+ through channels/transporters, such as the mitochondrial calcium uniporter (MCU), and influence the concentration of Ca2+ in both mitochondria and cytoplasm, thereby regulating cellular Ca2+ homeostasis. Mitochondrial Ca2+ transport-related processes are involved in important biological processes of tumor cells including proliferation, metabolism, and apoptosis. In particular, MCU and its regulatory proteins represent a new era in the study of MCU-mediated mitochondrial Ca2+ homeostasis in tumors. Through an in-depth analysis of the close correlation between mitochondrial Ca2+ and energy metabolism, autophagy, and apoptosis of tumor cells, we can provide a valuable reference for further understanding of how mitochondrial Ca2+ regulation helps diagnosis and therapy.
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Affiliation(s)
- Linlin Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China;
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
| | - Jingyi Qi
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
| | - Xu Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
| | - Xiya Zhao
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
| | - Peng An
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
- Correspondence: (P.A.); (Y.L.); (J.L.)
| | - Yongting Luo
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
- Correspondence: (P.A.); (Y.L.); (J.L.)
| | - Junjie Luo
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (J.Q.); (X.Z.); (X.Z.)
- Correspondence: (P.A.); (Y.L.); (J.L.)
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25
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Dudek J, Maack C. Mechano-energetic aspects of Barth syndrome. J Inherit Metab Dis 2022; 45:82-98. [PMID: 34423473 DOI: 10.1002/jimd.12427] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/28/2021] [Accepted: 08/19/2021] [Indexed: 12/22/2022]
Abstract
Energy-demanding organs like the heart are strongly dependent on oxidative phosphorylation in mitochondria. Oxidative phosphorylation is governed by the respiratory chain located in the inner mitochondrial membrane. The inner mitochondrial membrane is the only cellular membrane with significant amounts of the phospholipid cardiolipin, and cardiolipin was found to directly interact with a number of essential protein complexes, including respiratory chain complexes I to V. An inherited defect in the biogenesis of cardiolipin causes Barth syndrome, which is associated with cardiomyopathy, skeletal myopathy, neutropenia and growth retardation. Energy conversion is dependent on reducing equivalents, which are replenished by oxidative metabolism in the Krebs cycle. Cardiolipin deficiency in Barth syndrome also affects Krebs cycle activity, metabolite transport and mitochondrial morphology. During excitation-contraction coupling, calcium (Ca2+ ) released from the sarcoplasmic reticulum drives sarcomeric contraction. At the same time, Ca2+ influx into mitochondria drives the activation of Krebs cycle dehydrogenases and the regeneration of reducing equivalents. Reducing equivalents are essential not only for energy conversion, but also for maintaining a redox buffer, which is required to detoxify reactive oxygen species (ROS). Defects in CL may also affect Ca2+ uptake into mitochondria and thereby hamper energy supply and demand matching, but also detoxification of ROS. Here, we review the impact of cardiolipin deficiency on mitochondrial function in Barth syndrome and discuss potential therapeutic strategies.
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Affiliation(s)
- Jan Dudek
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
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26
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Lomize AL, Todd SC, Pogozheva ID. Spatial arrangement of proteins in planar and curved membranes by PPM 3.0. Protein Sci 2022; 31:209-220. [PMID: 34716622 PMCID: PMC8740824 DOI: 10.1002/pro.4219] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 01/03/2023]
Abstract
Cellular protrusions, invaginations, and many intracellular organelles have strongly curved membrane regions. Transmembrane and peripheral membrane proteins that induce, sense, or stabilize such regions cannot be properly fitted into a single flat bilayer. To treat such proteins, we developed a new method and a web tool, PPM 3.0, for positioning proteins in curved or planar, single or multiple membranes. This method determines the energetically optimal spatial position, the hydrophobic thickness, and the radius of intrinsic curvature of a membrane-deforming protein structure by arranging it in a single or several sphere-shaped or planar membrane sections. In addition, it can define the lipid-embedded regions of a protein that simultaneously spans several membranes or determine the optimal position of a peptide in a spherical micelle. The PPM 3.0 web server operates with 17 types of biological membranes and 4 types of artificial bilayers. It is publicly available at https://opm.phar.umich.edu/ppm_server3. PPM 3.0 was applied to identify and characterize arrangements in membranes of 128 proteins with a significant intrinsic curvature, such as BAR domains, annexins, Piezo, and MscS mechanosensitive channels, cation-chloride cotransporters, as well as mitochondrial ATP synthases, calcium uniporters, and TOM complexes. These proteins form large complexes that are mainly localized in mitochondria, plasma membranes, and endosomes. Structures of bacterial drug efflux pumps, AcrAB-TolC, MexAB-OrpM, and MacAB-TolC, were positioned in both membranes of the bacterial cell envelop, while structures of multimeric gap-junction channels were arranged in two opposed cellular membranes.
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Affiliation(s)
- Andrei L. Lomize
- College of Pharmacy, Department of Medicinal ChemistryUniversity of MichiganAnn ArborMichiganUSA
| | - Spencer C. Todd
- Department of Electrical Engineering and Computer Science, College of EngineeringUniversity of MichiganAnn ArborMichiganUSA
| | - Irina D. Pogozheva
- College of Pharmacy, Department of Medicinal ChemistryUniversity of MichiganAnn ArborMichiganUSA
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27
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Berezhnaya E, Hajnóczky G. How do MICUs gate the mitochondrial calcium uniporter? Cell Calcium 2021; 100:102497. [PMID: 34775300 DOI: 10.1016/j.ceca.2021.102497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 10/19/2022]
Affiliation(s)
- Elena Berezhnaya
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States.
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28
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Ghosh S, Zulkifli M, Joshi A, Venkatesan M, Cristel A, Vishnu N, Madesh M, Gohil VM. MCU-complex-mediated mitochondrial calcium signaling is impaired in Barth syndrome. Hum Mol Genet 2021; 31:376-385. [PMID: 34494107 DOI: 10.1093/hmg/ddab254] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 02/02/2023] Open
Abstract
Calcium signaling via mitochondrial calcium uniporter (MCU) complex coordinates mitochondrial bioenergetics with cellular energy demands. Emerging studies show that the stability and activity of the pore-forming subunit of the complex, MCU, is dependent on the mitochondrial phospholipid, cardiolipin (CL), but how this impacts calcium-dependent mitochondrial bioenergetics in CL-deficiency disorder like Barth syndrome (BTHS) is not known. Here we utilized multiple models of BTHS including yeast, mouse muscle cell line, as well as BTHS patient cells and cardiac tissue to show that CL is required for the abundance and stability of the MCU-complex regulatory subunit MICU1. Interestingly, the reduction in MICU1 abundance in BTHS mitochondria is independent of MCU. Unlike MCU and MICU1/MICU2, other subunit and associated factor of the uniporter complex, EMRE and MCUR1, respectively, are not affected in BTHS models. Consistent with the decrease in MICU1 levels, we show that the kinetics of MICU1-dependent mitochondrial calcium uptake is perturbed and acute stimulation of mitochondrial calcium signaling in BTHS myoblasts fails to activate pyruvate dehydrogenase, which in turn impairs the generation of reducing equivalents and blunts mitochondrial bioenergetics. Taken together, our findings suggest that defects in mitochondrial calcium signaling could contribute to cardiac and skeletal muscle pathologies observed in BTHS patients.
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Affiliation(s)
- Sagnika Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Mohammad Zulkifli
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Alaumy Joshi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Manigandan Venkatesan
- Department of Medicine, Cardiology Division, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Allen Cristel
- Department of Medicine, Cardiology Division, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Neelanjan Vishnu
- Department of Medicine, Cardiology Division, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Muniswamy Madesh
- Department of Medicine, Cardiology Division, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
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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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Structural characterization of the mitochondrial Ca 2+ uniporter provides insights into Ca 2+ uptake and regulation. iScience 2021; 24:102895. [PMID: 34401674 PMCID: PMC8353469 DOI: 10.1016/j.isci.2021.102895] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The mitochondrial uniporter is a Ca2+-selective ion-conducting channel in the inner mitochondrial membrane that is involved in various cellular processes. The components of this uniporter, including the pore-forming membrane subunit MCU and the modulatory subunits MCUb, EMRE, MICU1, and MICU2, have been identified in recent years. Previously, extensive studies revealed various aspects of uniporter activities and proposed multiple regulatory models of mitochondrial Ca2+ uptake. Recently, the individual auxiliary components of the uniporter and its holocomplex have been structurally characterized, providing the first insight into the component structures and their spatial relationship within the context of the uniporter. Here, we review recent uniporter structural studies in an attempt to establish an architectural framework, elucidating the mechanism that governs mitochondrial Ca2+ uptake and regulation, and to address some apparent controversies. This information could facilitate further characterization of mitochondrial Ca2+ permeation and a better understanding of uniporter-related disease conditions. The uniporter contains multiple subunits regulating various cellular processes Significant structural progresses have been made for the holo-complex of uniporter The holo-complex structures have inspired to propose several regulatory models
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31
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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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32
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Danese A, Leo S, Rimessi A, Wieckowski MR, Fiorica F, Giorgi C, Pinton P. Cell death as a result of calcium signaling modulation: A cancer-centric prospective. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119061. [PMID: 33991539 DOI: 10.1016/j.bbamcr.2021.119061] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/19/2021] [Accepted: 04/26/2021] [Indexed: 12/14/2022]
Abstract
Calcium ions (Ca2+) and the complex regulatory system governed by Ca2+ signaling have been described to be of crucial importance in numerous aspects related to cell life and death decisions, especially in recent years. The growing attention given to this second messenger is justified by the pleiotropic nature of Ca2+-binding proteins and transporters and their consequent involvement in cell fate decisions. A growing number of works highlight that deregulation of Ca2+ signaling and homoeostasis is often deleterious and drives pathological conditions; in particular, a disruption of the main Ca2+-mediated death mechanisms may lead to uncontrolled cell growth that results in cancer. In this work, we review the latest useful evidence to better understand the complex network of pathways by which Ca2+ regulates cell life and death decisions.
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Affiliation(s)
- Alberto Danese
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies, University of Ferrara, 44121 Ferrara, Italy
| | - Sara Leo
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies, University of Ferrara, 44121 Ferrara, Italy
| | - Alessandro Rimessi
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies, University of Ferrara, 44121 Ferrara, Italy
| | - Mariusz R Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Pasteur 3 Str., 02-093 Warsaw, Poland
| | | | - Carlotta Giorgi
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies, University of Ferrara, 44121 Ferrara, Italy.
| | - Paolo Pinton
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies, University of Ferrara, 44121 Ferrara, Italy.
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33
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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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34
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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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35
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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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36
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Wang C, Baradaran R, Long SB. Structure and Reconstitution of an MCU-EMRE Mitochondrial Ca 2+ Uniporter Complex. J Mol Biol 2020; 432:5632-5648. [PMID: 32841658 PMCID: PMC7577567 DOI: 10.1016/j.jmb.2020.08.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 10/23/2022]
Abstract
The proteins MCU and EMRE form the minimal functional unit of the mitochondrial calcium uniporter complex in metazoans, a highly selective and tightly controlled Ca2+ channel of the inner mitochondrial membrane that regulates cellular metabolism. Here we present functional reconstitution of an MCU-EMRE complex from the red flour beetle, Tribolium castaneum, and a cryo-EM structure of the complex at 3.5 Å resolution. Using a novel assay, we demonstrate robust Ca2+ uptake into proteoliposomes containing the purified complex. Uptake is dependent on EMRE and also on the mitochondrial lipid cardiolipin. The structure reveals a tetrameric channel with a single ion pore. EMRE is located at the periphery of the transmembrane domain and associates primarily with the first transmembrane helix of MCU. Coiled-coil and juxtamembrane domains within the matrix portion of the complex adopt markedly different conformations than in a structure of a human MCU-EMRE complex, suggesting that the structures represent different conformations of these functionally similar metazoan channels.
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Affiliation(s)
- Chongyuan Wang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Rozbeh Baradaran
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Stephen Barstow Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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37
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Carvalho EJ, Stathopulos PB, Madesh M. Regulation of Ca 2+ exchanges and signaling in mitochondria. CURRENT OPINION IN PHYSIOLOGY 2020; 17:197-206. [PMID: 33103015 DOI: 10.1016/j.cophys.2020.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondrial calcium (mCa2+) homeostasis also plays a key role in the buffering of cytosolic calcium (cCa2+) and calcium transported into the mitochondrial matrix regulates cellular metabolism, migration and cell fate decisions. Recent work has highlighted the importance of mCa2+ homeostasis in regulating cellular function. The discovery of the mCa2+ uptake complex has shed new light on the role of mCa2+ dynamics in cytoskeletal remodeling, mitochondrial shape and motility in cellular dynamics. Here we attempt to decipher the vast landscape of calcium regulatory effects of the mitochondria, the underlying mechanisms and the dynamics that control cellular function.
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Affiliation(s)
- Edmund J Carvalho
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228.,Department of Microbiology, Centre for Cellular Immunotherapies, University of Pennsylvania, Pennsylvania, 19104
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Muniswamy Madesh
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228
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