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Petersen CE, Sun J, Silva K, Kosmach A, Balaban RS, Murphy E. Increased mitochondrial free Ca 2+ during ischemia is suppressed, but not eliminated by, germline deletion of the mitochondrial Ca 2+ uniporter. Cell Rep 2023; 42:112735. [PMID: 37421627 PMCID: PMC10529381 DOI: 10.1016/j.celrep.2023.112735] [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: 10/07/2022] [Revised: 04/20/2023] [Accepted: 06/18/2023] [Indexed: 07/10/2023] Open
Abstract
Mitochondrial Ca2+ overload is proposed to regulate cell death via opening of the mitochondrial permeability transition pore. It is hypothesized that inhibition of the mitochondrial Ca2+ uniporter (MCU) will prevent Ca2+ accumulation during ischemia/reperfusion and thereby reduce cell death. To address this, we evaluate mitochondrial Ca2+ in ex-vivo-perfused hearts from germline MCU-knockout (KO) and wild-type (WT) mice using transmural spectroscopy. Matrix Ca2+ levels are measured with a genetically encoded, red fluorescent Ca2+ indicator (R-GECO1) using an adeno-associated viral vector (AAV9) for delivery. Due to the pH sensitivity of R-GECO1 and the known fall in pH during ischemia, hearts are glycogen depleted to decrease the ischemic fall in pH. At 20 min of ischemia, there is significantly less mitochondrial Ca2+ in MCU-KO hearts compared with MCU-WT controls. However, an increase in mitochondrial Ca2+ is present in MCU-KO hearts, suggesting that mitochondrial Ca2+ overload during ischemia is not solely dependent on MCU.
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Affiliation(s)
- Courtney E Petersen
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Junhui Sun
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kavisha Silva
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anna Kosmach
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert S Balaban
- Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elizabeth Murphy
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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2
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Saunders J, Sikder K, Phillips E, Ishwar A, Mothy D, Margulies KB, Choi JC. Med25 Limits Master Regulators That Govern Adipogenesis. Int J Mol Sci 2023; 24:6155. [PMID: 37047128 PMCID: PMC10093881 DOI: 10.3390/ijms24076155] [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: 02/20/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 04/14/2023] Open
Abstract
Mediator 25 (Med25) is a member of the mediator complex that relays signals from transcription factors to the RNA polymerase II machinery. Multiple transcription factors, particularly those involved in lipid metabolism, utilize the mediator complex, but how Med25 is involved in this context is unclear. We previously identified Med25 in a translatome screen of adult cardiomyocytes (CMs) in a novel cell type-specific model of LMNA cardiomyopathy. In this study, we show that Med25 upregulation is coincident with myocardial lipid accumulation. To ascertain the role of Med25 in lipid accumulation, we utilized iPSC-derived and neonatal CMs to recapitulate the in vivo phenotype by depleting lamins A and C (lamin A/C) in vitro. Although lamin A/C depletion elicits lipid accumulation, this effect appears to be mediated by divergent mechanisms dependent on the CM developmental state. To directly investigate Med25 in lipid accumulation, we induced adipogenesis in Med25-silenced 3T3-L1 preadipocytes and detected enhanced lipid accumulation. Assessment of pertinent mediators driving adipogenesis revealed that C/EBPα and PPARγ are super-induced by Med25 silencing. Our results indicate that Med25 limits adipogenic potential by suppressing the levels of master regulators that govern adipogenesis. Furthermore, we caution the use of early-developmental-stage cardiomyocytes to model adult-stage cells, particularly for dissecting metabolic perturbations emanating from LMNA mutations.
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Affiliation(s)
- Jasmine Saunders
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kunal Sikder
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Elizabeth Phillips
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Anurag Ishwar
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - David Mothy
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kenneth B. Margulies
- Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jason C. Choi
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
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3
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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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Bhullar S, Shah A, Dhalla N. Mechanisms for the development of heart failure and improvement of cardiac function by angiotensin-converting enzyme inhibitors. SCRIPTA MEDICA 2022. [DOI: 10.5937/scriptamed53-36256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, are well-known for the treatments of cardiovascular diseases, such as heart failure, hypertension and acute coronary syndrome. Several of these inhibitors including captopril, enalapril, ramipril, zofenopril and imidapril attenuate vasoconstriction, cardiac hypertrophy and adverse cardiac remodeling, improve clinical outcomes in patients with cardiac dysfunction and decrease mortality. Extensive experimental and clinical research over the past 35 years has revealed that the beneficial effects of ACE inhibitors in heart failure are associated with full or partial prevention of adverse cardiac remodeling. Since cardiac function is mainly determined by coordinated activities of different subcellular organelles, including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils, for regulating the intracellular concentration of Ca2+ and myocardial metabolism, there is ample evidence to suggest that adverse cardiac remodelling and cardiac dysfunction in the failing heart are the consequence of subcellular defects. In fact, the improvement of cardiac function by different ACE inhibitors has been demonstrated to be related to the attenuation of abnormalities in subcellular organelles for Ca2+-handling, metabolic alterations, signal transduction defects and gene expression changes in failing cardiomyocytes. Various ACE inhibitors have also been shown to delay the progression of heart failure by reducing the formation of angiotensin II, the development of oxidative stress, the level of inflammatory cytokines and the occurrence of subcellular defects. These observations support the view that ACE inhibitors improve cardiac function in the failing heart by multiple mechanisms including the reduction of oxidative stress, myocardial inflammation and Ca2+-handling abnormalities in cardiomyocytes.
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Joubert F, Puff N. Mitochondrial Cristae Architecture and Functions: Lessons from Minimal Model Systems. MEMBRANES 2021; 11:membranes11070465. [PMID: 34201754 PMCID: PMC8306996 DOI: 10.3390/membranes11070465] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/23/2022]
Abstract
Mitochondria are known as the powerhouse of eukaryotic cells. Energy production occurs in specific dynamic membrane invaginations in the inner mitochondrial membrane called cristae. Although the integrity of these structures is recognized as a key point for proper mitochondrial function, less is known about the mechanisms at the origin of their plasticity and organization, and how they can influence mitochondria function. Here, we review the studies which question the role of lipid membrane composition based mainly on minimal model systems.
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Affiliation(s)
- Frédéric Joubert
- Laboratoire Jean Perrin, CNRS, Sorbonne Université, UMR 8237, 75005 Paris, France;
| | - Nicolas Puff
- Faculté des Sciences et Ingénierie, Sorbonne Université, UFR 925 Physique, 75005 Paris, France
- Laboratoire Matière et Systèmes Complexes (MSC), Université Paris Diderot-Paris 7, UMR 7057 CNRS, 75013 Paris, France
- Correspondence:
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6
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Modesti L, Danese A, Angela Maria Vitto V, Ramaccini D, Aguiari G, Gafà R, Lanza G, Giorgi C, Pinton P. Mitochondrial Ca 2+ Signaling in Health, Disease and Therapy. Cells 2021; 10:cells10061317. [PMID: 34070562 PMCID: PMC8230075 DOI: 10.3390/cells10061317] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 12/12/2022] Open
Abstract
The divalent cation calcium (Ca2+) is considered one of the main second messengers inside cells and acts as the most prominent signal in a plethora of biological processes. Its homeostasis is guaranteed by an intricate and complex system of channels, pumps, and exchangers. In this context, by regulating cellular Ca2+ levels, mitochondria control both the uptake and release of Ca2+. Therefore, at the mitochondrial level, Ca2+ plays a dual role, participating in both vital physiological processes (ATP production and regulation of mitochondrial metabolism) and pathophysiological processes (cell death, cancer progression and metastasis). Hence, it is not surprising that alterations in mitochondrial Ca2+ (mCa2+) pathways or mutations in Ca2+ transporters affect the activities and functions of the entire cell. Indeed, it is widely recognized that dysregulation of mCa2+ signaling leads to various pathological scenarios, including cancer, neurological defects and cardiovascular diseases (CVDs). This review summarizes the current knowledge on the regulation of mCa2+ homeostasis, the related mechanisms and the significance of this regulation in physiology and human diseases. We also highlight strategies aimed at remedying mCa2+ dysregulation as promising therapeutical approaches.
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Affiliation(s)
- Lorenzo Modesti
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
| | - Alberto Danese
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
| | - Veronica Angela Maria Vitto
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
| | - Daniela Ramaccini
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
| | - Gianluca Aguiari
- Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy;
| | - Roberta Gafà
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (R.G.); (G.L.)
| | - Giovanni Lanza
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (R.G.); (G.L.)
| | - Carlotta Giorgi
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
| | - Paolo Pinton
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy; (L.M.); (A.D.); (V.A.M.V.); (D.R.); (C.G.)
- Correspondence: ; Tel.: +39-0532-455802
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Dridi H, Kushnir A, Zalk R, Yuan Q, Melville Z, Marks AR. Intracellular calcium leak in heart failure and atrial fibrillation: a unifying mechanism and therapeutic target. Nat Rev Cardiol 2020; 17:732-747. [PMID: 32555383 PMCID: PMC8362847 DOI: 10.1038/s41569-020-0394-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/06/2020] [Indexed: 12/14/2022]
Abstract
Ca2+ is a fundamental second messenger in all cell types and is required for numerous essential cellular functions, including cardiac and skeletal muscle contraction. The intracellular concentration of free Ca2+ ([Ca2+]) is regulated primarily by ion channels, pumps (ATPases), exchangers and Ca2+-binding proteins. Defective regulation of [Ca2+] is found in a diverse spectrum of pathological states that affect all the major organs. In the heart, abnormalities in the regulation of cytosolic and mitochondrial [Ca2+] occur in heart failure (HF) and atrial fibrillation (AF), two common forms of heart disease and leading contributors to morbidity and mortality. In this Review, we focus on the mechanisms that regulate ryanodine receptor 2 (RYR2), the major sarcoplasmic reticulum (SR) Ca2+-release channel in the heart, how RYR2 becomes dysfunctional in HF and AF, and its potential as a therapeutic target. Inherited RYR2 mutations and/or stress-induced phosphorylation and oxidation of the protein destabilize the closed state of the channel, resulting in a pathological diastolic Ca2+ leak from the SR that both triggers arrhythmias and impairs contractility. On the basis of our increased understanding of SR Ca2+ leak as a shared Ca2+-dependent pathological mechanism in HF and AF, a new class of drugs developed in our laboratory, known as rycals, which stabilize RYR2 channels and prevent Ca2+ leak from the SR, are undergoing investigation in clinical trials.
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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 and Surgeons, New York, NY, USA
| | - Alexander Kushnir
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Ran Zalk
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Qi Yuan
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Zephan Melville
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Andrew R Marks
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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8
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The Physiological and Pathological Roles of Mitochondrial Calcium Uptake in Heart. Int J Mol Sci 2020; 21:ijms21207689. [PMID: 33080805 PMCID: PMC7589179 DOI: 10.3390/ijms21207689] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 12/17/2022] Open
Abstract
Calcium ion (Ca2+) plays a critical role in the cardiac mitochondria function. Ca2+ entering the mitochondria is necessary for ATP production and the contractile activity of cardiomyocytes. However, excessive Ca2+ in the mitochondria results in mitochondrial dysfunction and cell death. Mitochondria maintain Ca2+ homeostasis in normal cardiomyocytes through a comprehensive regulatory mechanism by controlling the uptake and release of Ca2+ in response to the cellular demand. Understanding the mechanism of modulating mitochondrial Ca2+ homeostasis in the cardiomyocyte could bring new insights into the pathogenesis of cardiac disease and help developing the strategy to prevent the heart from damage at an early stage. In this review, we summarized the latest findings in the studies on the cardiac mitochondrial Ca2+ homeostasis, focusing on the regulation of mitochondrial calcium uptake, which acts as a double-edged sword in the cardiac function. Specifically, we discussed the dual roles of mitochondrial Ca2+ in mitochondrial activity and the impact on cardiac function, the molecular basis and regulatory mechanisms, and the potential future research interest.
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9
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Mitochondrial Ca 2+ regulation in the etiology of heart failure: physiological and pathophysiological implications. Acta Pharmacol Sin 2020; 41:1301-1309. [PMID: 32694759 PMCID: PMC7608470 DOI: 10.1038/s41401-020-0476-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/04/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022] Open
Abstract
Heart failure (HF) represents one of the leading causes of cardiovascular diseases with high rates of hospitalization, morbidity and mortality worldwide. Ample evidence has consolidated a crucial role for mitochondrial injury in the progression of HF. It is well established that mitochondrial Ca2+ participates in the regulation of a wide variety of biological processes, including oxidative phosphorylation, ATP synthesis, reactive oxygen species (ROS) generation, mitochondrial dynamics and mitophagy. Nonetheless, mitochondrial Ca2+ overload stimulates mitochondrial permeability transition pore (mPTP) opening and mitochondrial swelling, resulting in mitochondrial injury, apoptosis, cardiac remodeling, and ultimately development of HF. Moreover, mitochondria possess a series of Ca2+ transport influx and efflux channels, to buffer Ca2+ in the cytoplasm. Interaction at mitochondria-associated endoplasmic reticulum membranes (MAMs) may also participate in the regulation of mitochondrial Ca2+ homeostasis and plays an essential role in the progression of HF. Here, we provide an overview of regulation of mitochondrial Ca2+ homeostasis in maintenance of cardiac function, in an effort to identify novel therapeutic strategies for the management of HF.
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Ca 2+ Channels Mediate Bidirectional Signaling between Sarcolemma and Sarcoplasmic Reticulum in Muscle Cells. Cells 2019; 9:cells9010055. [PMID: 31878335 PMCID: PMC7016941 DOI: 10.3390/cells9010055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 12/21/2022] Open
Abstract
The skeletal muscle and myocardial cells present highly specialized structures; for example, the close interaction between the sarcoplasmic reticulum (SR) and mitochondria—responsible for excitation-metabolism coupling—and the junction that connects the SR with T-tubules, critical for excitation-contraction (EC) coupling. The mechanisms that underlie EC coupling in these two cell types, however, are fundamentally distinct. They involve the differential expression of Ca2+ channel subtypes: CaV1.1 and RyR1 (skeletal), vs. CaV1.2 and RyR2 (cardiac). The CaV channels transform action potentials into elevations of cytosolic Ca2+, by activating RyRs and thus promoting SR Ca2+ release. The high levels of Ca2+, in turn, stimulate not only the contractile machinery but also the generation of mitochondrial reactive oxygen species (ROS). This forward signaling is reciprocally regulated by the following feedback mechanisms: Ca2+-dependent inactivation (of Ca2+ channels), the recruitment of Na+/Ca2+ exchanger activity, and oxidative changes in ion channels and transporters. Here, we summarize both well-established concepts and recent advances that have contributed to a better understanding of the molecular mechanisms involved in this bidirectional signaling.
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11
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Recent Advances in Pharmacological and Non-Pharmacological Strategies of Cardioprotection. Int J Mol Sci 2019; 20:ijms20164002. [PMID: 31426434 PMCID: PMC6720817 DOI: 10.3390/ijms20164002] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/30/2019] [Accepted: 07/30/2019] [Indexed: 02/08/2023] Open
Abstract
Ischemic heart diseases (IHD) are the leading cause of death worldwide. Although the principal form of treatment of IHD is myocardial reperfusion, the recovery of coronary blood flow after ischemia can cause severe and fatal cardiac dysfunctions, mainly due to the abrupt entry of oxygen and ionic deregulation in cardiac cells. The ability of these cells to protect themselves against injury including ischemia and reperfusion (I/R), has been termed “cardioprotection”. This protective response can be stimulated by pharmacological agents (adenosine, catecholamines and others) and non-pharmacological procedures (conditioning, hypoxia and others). Several intracellular signaling pathways mediated by chemical messengers (enzymes, protein kinases, transcription factors and others) and cytoplasmic organelles (mitochondria, sarcoplasmic reticulum, nucleus and sarcolemma) are involved in cardioprotective responses. Therefore, advancement in understanding the cellular and molecular mechanisms involved in the cardioprotective response can lead to the development of new pharmacological and non-pharmacological strategies for cardioprotection, thus contributing to increasing the efficacy of IHD treatment. In this work, we analyze the recent advances in pharmacological and non-pharmacological strategies of cardioprotection.
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Hamilton S, Terentyev D. Altered Intracellular Calcium Homeostasis and Arrhythmogenesis in the Aged Heart. Int J Mol Sci 2019; 20:ijms20102386. [PMID: 31091723 PMCID: PMC6566636 DOI: 10.3390/ijms20102386] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 04/29/2019] [Accepted: 05/08/2019] [Indexed: 12/17/2022] Open
Abstract
Aging of the heart is associated with a blunted response to sympathetic stimulation, reduced contractility, and increased propensity for arrhythmias, with the risk of sudden cardiac death significantly increased in the elderly population. The altered cardiac structural and functional phenotype, as well as age-associated prevalent comorbidities including hypertension and atherosclerosis, predispose the heart to atrial fibrillation, heart failure, and ventricular tachyarrhythmias. At the cellular level, perturbations in mitochondrial function, excitation-contraction coupling, and calcium homeostasis contribute to this electrical and contractile dysfunction. Major determinants of cardiac contractility are the intracellular release of Ca2+ from the sarcoplasmic reticulum by the ryanodine receptors (RyR2), and the following sequestration of Ca2+ by the sarco/endoplasmic Ca2+-ATPase (SERCa2a). Activity of RyR2 and SERCa2a in myocytes is not only dependent on expression levels and interacting accessory proteins, but on fine-tuned regulation via post-translational modifications. In this paper, we review how aberrant changes in intracellular Ca2+ cycling via these proteins contributes to arrhythmogenesis in the aged heart.
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Affiliation(s)
- Shanna Hamilton
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
| | - Dmitry Terentyev
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
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13
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Mitochondrial calcium signalling and neurodegenerative diseases. Neuronal Signal 2018; 2:NS20180061. [PMID: 32714593 PMCID: PMC7373239 DOI: 10.1042/ns20180061] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/06/2018] [Accepted: 09/20/2018] [Indexed: 12/11/2022] Open
Abstract
Calcium is utilised by cells in signalling and in regulating ATP production; it also contributes to cell survival and, when concentrations are unbalanced, triggers pathways for cell death. Mitochondria contribute to calcium buffering, meaning that mitochondrial calcium uptake and release is intimately related to cytosolic calcium concentrations. This review focuses on the proteins contributing to mitochondrial calcium homoeostasis, the roles of the mitochondrial permeability transition pore (MPTP) and mitochondrial calcium-activated proteins, and their relevance in neurodegenerative pathologies. It also covers alterations to calcium homoeostasis in Friedreich ataxia (FA).
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14
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Ai WL, Dong LY, Wang J, Li ZW, Wang X, Gao J, Wu Y, An W. Deficiency in augmenter of liver regeneration accelerates liver fibrosis by promoting migration of hepatic stellate cell. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3780-3791. [DOI: 10.1016/j.bbadis.2018.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 08/19/2018] [Accepted: 09/09/2018] [Indexed: 12/14/2022]
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15
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Rossi A, Pizzo P, Filadi R. Calcium, mitochondria and cell metabolism: A functional triangle in bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:1068-1078. [PMID: 30982525 DOI: 10.1016/j.bbamcr.2018.10.016] [Citation(s) in RCA: 222] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 12/18/2022]
Abstract
The versatility of mitochondrial metabolism and its fine adjustments to specific physiological or pathological conditions regulate fundamental cell pathways, ranging from proliferation to apoptosis. In particular, Ca2+ signalling has emerged as a key player exploited by mitochondria to tune their activity according with cell demand. The functional interaction between mitochondria and endoplasmic reticulum (ER) deeply impacts on the correct mitochondrial Ca2+ signal, thus modulating cell bioenergetics and functionality. Indeed, Ca2+ released by the ER is taken up by mitochondria where, both in the intermembrane space and in the matrix, it regulates the activity of transporters, enzymes and proteins involved in organelles' metabolism. In this review, we will briefly summarize Ca2+-dependent mechanisms involved in the regulation of mitochondrial activity. Moreover, we will discuss some recent reports, in which alterations in mitochondrial Ca2+ signalling have been associated with specific pathological conditions, such as neurodegeneration and cancer.
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Affiliation(s)
- Alice Rossi
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy; Neuroscience Institute - Italian National Research Council (CNR), 35131 Padova, Italy.
| | - Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
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16
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Jaquenod De Giusti C, Roman B, Das S. The Influence of MicroRNAs on Mitochondrial Calcium. Front Physiol 2018; 9:1291. [PMID: 30298016 PMCID: PMC6160583 DOI: 10.3389/fphys.2018.01291] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/27/2018] [Indexed: 01/13/2023] Open
Abstract
Abnormal mitochondrial calcium ([Ca2+]m) handling and energy deficiency results in cellular dysfunction and cell death. Recent studies suggest that nuclear-encoded microRNAs (miRNA) are able to translocate in to the mitochondrial compartment, and modulate mitochondrial activities, including [Ca2+]m uptake. Apart from this subset of miRNAs, there are several miRNAs that have been reported to target genes that play a role in maintaining [Ca2+]m levels in the cytoplasm. It is imperative to validate miRNAs that alter [Ca2+]m handling, and thereby alter cellular fate. The focus of this review is to highlight the mitochondrial miRNAs (MitomiRs), and other cytosolic miRNAs that target mRNAs which play an important role in [Ca2+]m handling.
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Affiliation(s)
- Carolina Jaquenod De Giusti
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Barbara Roman
- Department of Pathology, Johns Hopkins University, Baltimore, MD, United States
| | - Samarjit Das
- Department of Pathology, Johns Hopkins University, Baltimore, MD, United States
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17
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Sventzouri S, Nanas I, Vakrou S, Kapelios C, Sousonis V, Sfakianaki T, Papalois A, Manolis AS, Nanas JN, Malliaras K. Pharmacologic inhibition of the mitochondrial Na +/Ca 2+ exchanger protects against ventricular arrhythmias in a porcine model of ischemia-reperfusion. Hellenic J Cardiol 2018; 59:217-222. [PMID: 29292245 DOI: 10.1016/j.hjc.2017.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 12/03/2017] [Accepted: 12/22/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The mitochondrial Na+/Ca2+ exchanger (mNCX) has been implicated in the pathogenesis of arrhythmogenicity and myocardial reperfusion injury, rendering its inhibition a potential therapeutic strategy. We examined the effects of CGP-37157, a selective mNCX inhibitor, on arrhythmogenesis, infarct size (IS), and no reflow area (NRA) in a porcine model of ischemia-reperfusion. METHODS Forty pigs underwent myocardial ischemia for 60 minutes, followed by 2 hours of reperfusion. Animals were randomized to receive intracoronary infusion of 0.02 mg/kg CGP-37157 or vehicle, either before ischemia (n=17) or before reperfusion (n=17). Animals were monitored for arrhythmias. Myocardial area at risk (AR), IS, and NRA were measured by histopathology. RESULTS AR, NRA, and IS were comparable between groups. Administration of CGP-37157 before ischemia resulted in the following: (a) suppression of ventricular tachyarrhythmias (events/pig: 1.5±1.1 vs 3.5±1.9, p=0.014), (b) easier cardioversion of ventricular tachyarrhythmias (defibrillations required for cardioversion of each episode: 2.6±2.3 vs 6.2±2.1, p=0.006), and (c) decreased maximal depression of the J point (0.75±0.27 mm vs 1.75±0.82 mm, p=0.007), compared to controls. Administration of CGP-37157 before reperfusion expedited ST-segment resolution; complete ST-segment resolution within 30 minutes of reperfusion was observed in 7/8 CGP-37157-treated animals versus 1/9 controls (p=0.003). CONCLUSIONS In a porcine model of myocardial infarction, intracoronary administration of CGP-37157 did not decrease IS or NRA. However, it suppressed ventricular arrhythmias, decreased depression of the J point during ischemia and expedited ST-segment resolution after reperfusion. These findings motivate further investigation of pharmacologic mNCX inhibition as a potential therapeutic strategy to suppress arrhythmias in the injured heart.
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Affiliation(s)
- Stefania Sventzouri
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Ioannis Nanas
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Styliani Vakrou
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Chris Kapelios
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Vasilios Sousonis
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Titika Sfakianaki
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | | | - Antonis S Manolis
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - John N Nanas
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece
| | - Konstantinos Malliaras
- 3rd Department of Cardiology, University of Athens School of Medicine, 11 527, Athens, Greece.
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18
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The relationship between the ionized Ca concentration and mitochondrial function. UKRAINIAN BIOCHEMICAL JOURNAL 2018. [DOI: 10.15407/ubj90.03.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Targeting mitochondrial calcium transport in myocardial infarction. Hellenic J Cardiol 2018; 59:223-225. [PMID: 29940221 DOI: 10.1016/j.hjc.2018.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/01/2018] [Accepted: 06/08/2018] [Indexed: 01/27/2023] Open
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20
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Abstract
Mitochondrial dysfunction underlines a multitude of pathologies; however, studies are scarce that rescue the mitochondria for cellular resuscitation. Exploration into the protective role of mitochondrial transcription factor A (TFAM) and its mitochondrial functions respective to cardiomyocyte death are in need of further investigation. TFAM is a gene regulator that acts to mitigate calcium mishandling and ROS production by wrapping around mitochondrial DNA (mtDNA) complexes. TFAM's regulatory functions over serca2a, NFAT, and Lon protease contribute to cardiomyocyte stability. Calcium- and ROS-dependent proteases, calpains, and matrix metalloproteinases (MMPs) are abundantly found upregulated in the failing heart. TFAM's regulatory role over ROS production and calcium mishandling leads to further investigation into the cardioprotective role of exogenous TFAM. In an effort to restabilize physiological and contractile activity of cardiomyocytes in HF models, we propose that TFAM-packed exosomes (TFAM-PE) will act therapeutically by mitigating mitochondrial dysfunction. Notably, this is the first mention of exosomal delivery of transcription factors in the literature. Here we elucidate the role of TFAM in mitochondrial rescue and focus on its therapeutic potential.
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Affiliation(s)
- George H Kunkel
- Department of Physiology and Biophysics, Health Sciences Centre, 1216, School of Medicine, University of Louisville, 500, South Preston Street, Louisville, KY, 40202, USA
| | - Pankaj Chaturvedi
- Department of Physiology and Biophysics, Health Sciences Centre, 1216, School of Medicine, University of Louisville, 500, South Preston Street, Louisville, KY, 40202, USA.
| | - Suresh C Tyagi
- Department of Physiology and Biophysics, Health Sciences Centre, 1216, School of Medicine, University of Louisville, 500, South Preston Street, Louisville, KY, 40202, USA
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21
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Purroy R, Britti E, Delaspre F, Tamarit J, Ros J. Mitochondrial pore opening and loss of Ca 2+ exchanger NCLX levels occur after frataxin depletion. Biochim Biophys Acta Mol Basis Dis 2018; 1864:618-631. [PMID: 29223733 DOI: 10.1016/j.bbadis.2017.12.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/29/2017] [Accepted: 12/05/2017] [Indexed: 12/12/2022]
Abstract
Frataxin-deficient neonatal rat cardiomyocytes and dorsal root ganglia neurons have been used as cell models of Friedreich ataxia. In previous work we show that frataxin depletion resulted in mitochondrial swelling and lipid droplet accumulation in cardiomyocytes, and compromised DRG neurons survival. Now, we show that these cells display reduced levels of the mitochondrial calcium transporter NCLX that can be restored by calcium-chelating agents and by external addition of frataxin fused to TAT peptide. Also, the transcription factor NFAT3, involved in cardiac hypertrophy and apoptosis, becomes activated by dephosphorylation in both cardiomyocytes and DRG neurons. In cardiomyocytes, frataxin depletion also results in mitochondrial permeability transition pore opening. Since the pore opening can be inhibited by cyclosporin A, we show that this treatment reduces lipid droplets and mitochondrial swelling in cardiomyocytes, restores DRG neuron survival and inhibits NFAT dephosphorylation. These results highlight the importance of calcium homeostasis and that targeting mitochondrial pore by repurposing cyclosporin A, could be envisaged as a new strategy to treat the disease.
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Affiliation(s)
- R Purroy
- Department of Ciències Mèdiques Bàsiques, Fac. Medicina, University of Lleida, IRB Lleida, Lleida, Spain
| | - E Britti
- Department of Ciències Mèdiques Bàsiques, Fac. Medicina, University of Lleida, IRB Lleida, Lleida, Spain
| | - F Delaspre
- Department of Ciències Mèdiques Bàsiques, Fac. Medicina, University of Lleida, IRB Lleida, Lleida, Spain
| | - J Tamarit
- Department of Ciències Mèdiques Bàsiques, Fac. Medicina, University of Lleida, IRB Lleida, Lleida, Spain
| | - J Ros
- Department of Ciències Mèdiques Bàsiques, Fac. Medicina, University of Lleida, IRB Lleida, Lleida, Spain.
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22
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Content of mitochondrial calcium uniporter (MCU) in cardiomyocytes is regulated by microRNA-1 in physiologic and pathologic hypertrophy. Proc Natl Acad Sci U S A 2017; 114:E9006-E9015. [PMID: 29073097 DOI: 10.1073/pnas.1708772114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The mitochondrial Ca2+ uniporter complex (MCUC) is a multimeric ion channel which, by tuning Ca2+ influx into the mitochondrial matrix, finely regulates metabolic energy production. In the heart, this dynamic control of mitochondrial Ca2+ uptake is fundamental for cardiomyocytes to adapt to either physiologic or pathologic stresses. Mitochondrial calcium uniporter (MCU), which is the core channel subunit of MCUC, has been shown to play a critical role in the response to β-adrenoreceptor stimulation occurring during acute exercise. The molecular mechanisms underlying the regulation of MCU, in conditions requiring chronic increase in energy production, such as physiologic or pathologic cardiac growth, remain elusive. Here, we show that microRNA-1 (miR-1), a member of the muscle-specific microRNA (myomiR) family, is responsible for direct and selective targeting of MCU and inhibition of its translation, thereby affecting the capacity of the mitochondrial Ca2+ uptake machinery. Consistent with the role of miR-1 in heart development and cardiomyocyte hypertrophic remodeling, we additionally found that MCU levels are inversely related with the myomiR content, in murine and, remarkably, human hearts from both physiologic (i.e., postnatal development and exercise) and pathologic (i.e., pressure overload) myocardial hypertrophy. Interestingly, the persistent activation of β-adrenoreceptors is likely one of the upstream repressors of miR-1 as treatment with β-blockers in pressure-overloaded mouse hearts prevented its down-regulation and the consequent increase in MCU content. Altogether, these findings identify the miR-1/MCU axis as a factor in the dynamic adaptation of cardiac cells to hypertrophy.
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23
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Vettor R, Inzucchi SE, Fioretto P. The cardiovascular benefits of empagliflozin: SGLT2-dependent and -independent effects. Diabetologia 2017; 60:395-398. [PMID: 28074254 DOI: 10.1007/s00125-016-4194-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 11/15/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Roberto Vettor
- Internal Medicine 3, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padova, Italy.
| | - Silvio E Inzucchi
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Paola Fioretto
- Internal Medicine 3, Department of Medicine, University of Padua, via Giustiniani 2, 35128, Padova, Italy.
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24
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5-HTR3 and 5-HTR4 located on the mitochondrial membrane and functionally regulated mitochondrial functions. Sci Rep 2016; 6:37336. [PMID: 27874067 PMCID: PMC5118798 DOI: 10.1038/srep37336] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/25/2016] [Indexed: 11/29/2022] Open
Abstract
5-HT has been reported to possess significant effects on cardiac activities, but activation of 5-HTR on the cell membrane failed to illustrate the controversial cardiac reaction. Because 5-HT constantly comes across the cell membrane via 5-HT transporter (5-HTT) into the cytoplasm, whether 5-HTR is functional present on the cellular organelles is unknown. Here we show 5-HTR3 and 5-HTR4 were located in cardiac mitochondria, and regulated mitochondrial activities and cellular functions. Knock down 5-HTR3 and 5-HTR4 in neonatal cardiomyocytes resulted in significant increase of cell damage in response to hypoxia, and also led to alternation in heart beating. Activation of 5-HTR4 attenuated mitochondrial Ca2+ uptake under the both normoxic and hypoxic conditions, whereas 5-HTR3 augmented Ca2+ uptake only under hypoxia. 5-HTR3 and 5-HTR4 exerted the opposite effects on the mitochondrial respiration: 5-HTR3 increased RCR (respiration control ratio), but 5-HTR4 reduced RCR. Moreover, activation of 5-HTR3 and 5-HTR4 both significantly inhibited the opening of mPTP. Our results provided the first evidence that 5-HTR as a GPCR and an ion channel, functionally expressed in mitochondria and participated in the mitochondria function and regulation to maintain homeostasis of mitochondrial [Ca2+], ROS, and ATP generation efficiency in cardiomyocytes in response to stress and O2 tension.
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25
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Chen Q, Lesnefsky EJ. Heart mitochondria and calpain 1: Location, function, and targets. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2372-8. [PMID: 26259540 DOI: 10.1016/j.bbadis.2015.08.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 07/17/2015] [Accepted: 08/06/2015] [Indexed: 12/22/2022]
Abstract
Calpain 1 is an ubiquitous Ca(2+)-dependent cysteine protease. Although calpain 1 has been found in cardiac mitochondria, the exact location within mitochondrial compartments and its function remain unclear. The aim of the current review is to discuss the localization of calpain 1 in different mitochondrial compartments in relationship to its function, especially in pathophysiological conditions. Briefly, mitochondrial calpain 1 (mit-CPN1) is located within the intermembrane space and mitochondrial matrix. Activation of the mit-CPN1 within intermembrane space cleaves apoptosis inducing factor (AIF), whereas the activated mit-CPN1 within matrix cleaves complex I subunits and metabolic enzymes. Inhibition of the mit-CPN1 could be a potential strategy to decrease cardiac injury during ischemia-reperfusion.
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Affiliation(s)
- Qun Chen
- Department of Medicine (Division of Cardiology, Pauley Heart Center), Virginia Commonwealth University, Richmond, VA 23298, United States.
| | - Edward J Lesnefsky
- Department of Medicine (Division of Cardiology, Pauley Heart Center), Virginia Commonwealth University, Richmond, VA 23298, United States; Department of Biochemistry, Virginia Commonwealth University, Richmond, VA 23298, United States; Department of Physiology, Virginia Commonwealth University, Richmond, VA 23298, United States; McGuire VA Medical Center, Richmond, VA 23249, United States
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26
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Abstract
Calcium (Ca2+) released from the sarcoplasmic reticulum (SR) is crucial for excitation-contraction (E-C) coupling. Mitochondria, the major source of energy, in the form of ATP, required for cardiac contractility, are closely interconnected with the SR, and Ca2+ is essential for optimal function of these organelles. However, Ca2+ accumulation can impair mitochondrial function, leading to reduced ATP production and increased release of reactive oxygen species (ROS). Oxidative stress contributes to heart failure (HF), but whether mitochondrial Ca2+ plays a mechanistic role in HF remains unresolved. Here, we show for the first time, to our knowledge, that diastolic SR Ca2+ leak causes mitochondrial Ca2+ overload and dysfunction in a murine model of postmyocardial infarction HF. There are two forms of Ca2+ release channels on cardiac SR: type 2 ryanodine receptors (RyR2s) and type 2 inositol 1,4,5-trisphosphate receptors (IP3R2s). Using murine models harboring RyR2 mutations that either cause or inhibit SR Ca2+ leak, we found that leaky RyR2 channels result in mitochondrial Ca2+ overload, dysmorphology, and malfunction. In contrast, cardiac-specific deletion of IP3R2 had no major effect on mitochondrial fitness in HF. Moreover, genetic enhancement of mitochondrial antioxidant activity improved mitochondrial function and reduced posttranslational modifications of RyR2 macromolecular complex. Our data demonstrate that leaky RyR2, but not IP3R2, channels cause mitochondrial Ca2+ overload and dysfunction in HF.
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27
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Holmström KM, Pan X, Liu JC, Menazza S, Liu J, Nguyen TT, Pan H, Parks RJ, Anderson S, Noguchi A, Springer D, Murphy E, Finkel T. Assessment of cardiac function in mice lacking the mitochondrial calcium uniporter. J Mol Cell Cardiol 2015; 85:178-82. [PMID: 26057074 DOI: 10.1016/j.yjmcc.2015.05.022] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 05/19/2015] [Accepted: 05/29/2015] [Indexed: 01/08/2023]
Abstract
Mitochondrial calcium is thought to play an important role in the regulation of cardiac bioenergetics and function. The entry of calcium into the mitochondrial matrix requires that the divalent cation pass through the inner mitochondrial membrane via a specialized pore known as the mitochondrial calcium uniporter (MCU). Here, we use mice deficient of MCU expression to rigorously assess the role of mitochondrial calcium in cardiac function. Mitochondria isolated from MCU(-/-) mice have reduced matrix calcium levels, impaired calcium uptake and a defect in calcium-stimulated respiration. Nonetheless, we find that the absence of MCU expression does not affect basal cardiac function at either 12 or 20months of age. Moreover, the physiological response of MCU(-/-) mice to isoproterenol challenge or transverse aortic constriction appears similar to control mice. Thus, while mitochondria derived from MCU(-/-) mice have markedly impaired mitochondrial calcium handling, the hearts of these animals surprisingly appear to function relatively normally under basal conditions and during stress.
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Affiliation(s)
- Kira M Holmström
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Xin Pan
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA; Laboratory of Cell Biology, National Center of Biomedical Analysis, Beijing 100850, China
| | - Julia C Liu
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Sara Menazza
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Jie Liu
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Tiffany T Nguyen
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Haihui Pan
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Randi J Parks
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Stasia Anderson
- Animal MRI Core, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Audrey Noguchi
- Murine Phenotyping Core, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Danielle Springer
- Murine Phenotyping Core, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Elizabeth Murphy
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Toren Finkel
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA.
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28
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Rasola A, Bernardi P. Reprint of "The mitochondrial permeability transition pore and its adaptive responses in tumor cells". Cell Calcium 2015; 58:18-26. [PMID: 25828565 DOI: 10.1016/j.ceca.2015.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 02/07/2023]
Abstract
This review covers recent progress on the nature of the mitochondrial permeability transition pore (PTP) – a key effector in the mitochondrial pathways to cell death – and on the adaptive responses of tumor cells that desensitize the PTP to Ca(2+) and reactive oxygen species (ROS), thereby playing an important role in the resistance of tumors to cell death. The discovery that the PTP forms from dimers of F-ATP synthase; and the definition of the Ca(2+)- and ROS-dependent signaling pathways affecting the transition of the F-ATP synthase from an energy-conserving to an energy-dissipating device open new perspectives for therapeutic intervention in cancer cells.
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Affiliation(s)
- Andrea Rasola
- Department of Biomedical Sciences and CNR Neuroscience Institute, University of Padova, Italy.
| | - Paolo Bernardi
- Department of Biomedical Sciences and CNR Neuroscience Institute, University of Padova, Italy.
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29
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Rasola A, Bernardi P. The mitochondrial permeability transition pore and its adaptive responses in tumor cells. Cell Calcium 2014; 56:437-45. [PMID: 25454774 PMCID: PMC4274314 DOI: 10.1016/j.ceca.2014.10.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 01/12/2023]
Abstract
This review covers recent progress on the nature of the mitochondrial permeability transition pore (PTP) - a key effector in the mitochondrial pathways to cell death - and on the adaptive responses of tumor cells that desensitize the PTP to Ca(2+) and reactive oxygen species (ROS), thereby playing an important role in the resistance of tumors to cell death. The discovery that the PTP forms from dimers of F-ATP synthase; and the definition of the Ca(2+)- and ROS-dependent signaling pathways affecting the transition of the F-ATP synthase from an energy-conserving to an energy-dissipating device open new perspectives for therapeutic intervention in cancer cells.
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Affiliation(s)
- Andrea Rasola
- Department of Biomedical Sciences and CNR Neuroscience Institute, University of Padova, Italy.
| | - Paolo Bernardi
- Department of Biomedical Sciences and CNR Neuroscience Institute, University of Padova, Italy.
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30
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Vygodina TV, Kirichenko A, Konstantinov AA. Cation binding site of cytochrome c oxidase: progress report. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1188-95. [PMID: 24607866 DOI: 10.1016/j.bbabio.2014.02.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/18/2014] [Accepted: 02/24/2014] [Indexed: 12/15/2022]
Abstract
Cytochrome c oxidase from bovine heart binds Ca(2+) reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+) shifts the absorption spectrum of heme a, which allowed earlier the determination of the kinetic and equilibrium characteristics of the binding, and, as shown recently, the binding of calcium to the site inhibits cytochrome oxidase activity at low turnover rates of the enzyme [Vygodina, Т., Kirichenko, A., Konstantinov, A.A (2013). Direct Regulation of Cytochrome c Oxidase by Calcium Ions. PloS ONE 8, e74436]. This paper summarizes further progress in the studies of the Cation Binding Site in this group presenting the results to be reported at 18th EBEC Meeting in Lisbon, 2014. The paper revises specificity of the bovine oxidase Cation Binding Site for different cations, describes dependence of the Ca(2+)-induced inhibition on turnover rate of the enzyme and reports very high affinity binding of calcium with the "slow" form of cytochrome oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.
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Affiliation(s)
- Tatiana V Vygodina
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Moscow State University, Russia
| | - Anna Kirichenko
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Moscow State University, Russia
| | - Alexander A Konstantinov
- A.N. Belozersky Research Institute of Physico-Chemical Biology, Moscow State University, Russia.
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31
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Coronel R, Wilders R, Verkerk AO, Wiegerinck RF, Benoist D, Bernus O. Electrophysiological changes in heart failure and their implications for arrhythmogenesis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2432-41. [DOI: 10.1016/j.bbadis.2013.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 04/01/2013] [Indexed: 01/07/2023]
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32
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Zhao Z, Gordan R, Wen H, Fefelova N, Zang WJ, Xie LH. Modulation of intracellular calcium waves and triggered activities by mitochondrial ca flux in mouse cardiomyocytes. PLoS One 2013; 8:e80574. [PMID: 24348912 PMCID: PMC3857829 DOI: 10.1371/journal.pone.0080574] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 10/04/2013] [Indexed: 12/23/2022] Open
Abstract
Recent studies have suggested that mitochondria may play important roles in the Ca(2+) homeostasis of cardiac myocytes. However, it is still unclear if mitochondrial Ca(2+) flux can regulate the generation of Ca(2+) waves (CaWs) and triggered activities in cardiac myocytes. In the present study, intracellular/cytosolic Ca(2+) (Cai (2+)) was imaged in Fluo-4-AM loaded mouse ventricular myocytes. Spontaneous sarcoplasmic reticulum (SR) Ca(2+) release and CaWs were induced in the presence of high (4 mM) external Ca(2+) (Cao (2+)). The protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) reversibly raised basal Cai (2+) levels even after depletion of SR Ca(2+) in the absence of Cao (2+) , suggesting Ca(2+) release from mitochondria. FCCP at 0.01 - 0.1 µM partially depolarized the mitochondrial membrane potential (Δψ m ) and increased the frequency and amplitude of CaWs in a dose-dependent manner. Simultaneous recording of cell membrane potentials showed the augmentation of delayed afterdepolarization amplitudes and frequencies, and induction of triggered action potentials. The effect of FCCP on CaWs was mimicked by antimycin A (an electron transport chain inhibitor disrupting Δψ m ) or Ru360 (a mitochondrial Ca(2+) uniporter inhibitor), but not by oligomycin (an ATP synthase inhibitor) or iodoacetic acid (a glycolytic inhibitor), excluding the contribution of intracellular ATP levels. The effects of FCCP on CaWs were counteracted by the mitochondrial permeability transition pore blocker cyclosporine A, or the mitochondrial Ca(2+) uniporter activator kaempferol. Our results suggest that mitochondrial Ca(2+) release and uptake exquisitely control the local Ca(2+) level in the micro-domain near SR ryanodine receptors and play an important role in regulation of intracellular CaWs and arrhythmogenesis.
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Affiliation(s)
- Zhenghang Zhao
- Department of Pharmacology, School of Medicine, Xi’an Jiaotong University, Xi’an, China
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Richard Gordan
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Hairuo Wen
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
- Department of Reproductive and Genetic Toxicology, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, P.R. China
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Wei-Jin Zang
- Department of Pharmacology, School of Medicine, Xi’an Jiaotong University, Xi’an, China
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
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Vygodina T, Kirichenko A, Konstantinov AA. Direct regulation of cytochrome c oxidase by calcium ions. PLoS One 2013; 8:e74436. [PMID: 24058566 PMCID: PMC3769247 DOI: 10.1371/journal.pone.0074436] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/01/2013] [Indexed: 12/16/2022] Open
Abstract
Cytochrome c oxidase from bovine heart binds Ca2+ reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca2+ shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca2+ on the functional characteristics of cytochrome oxidase was revealed earlier. Here we report that Ca2+ inhibits cytochrome oxidase activity of isolated bovine heart enzyme by 50–60% with Ki of ∼1 µM, close to Kd of calcium binding with the oxidase determined spectrophotometrically. The inhibition is observed only at low, but physiologically relevant, turnover rates of the enzyme (∼10 s−1 or less). No inhibitory effect of Ca2+ is observed under conventional conditions of cytochrome c oxidase activity assays (turnover number >100 s−1 at pH 8), which may explain why the effect was not noticed earlier. The inhibition is specific for Ca2+ and is reversed by EGTA. Na+ ions that compete with Ca2+ for binding with the Cation Binding Site, do not affect significantly activity of the enzyme but counteract the inhibitory effect of Ca2+. The Ca2+-induced inhibition of cytochrome c oxidase is observed also with the uncoupled mitochondria from several rat tissues. At the same time, calcium ions do not inhibit activity of the homologous bacterial cytochrome oxidases. Possible mechanisms of the inhibition are discussed as well as potential physiological role of Ca2+ binding with cytochrome oxidase. Ca2+- binding at the Cation Binding Site is proposed to inhibit proton-transfer through the exit part of the proton conducting pathway H in the mammalian oxidases.
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Affiliation(s)
- Tatiana Vygodina
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - Anna Kirichenko
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - Alexander A. Konstantinov
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
- * E-mail:
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Activity of the mitochondrial calcium uniporter varies greatly between tissues. Nat Commun 2013; 3:1317. [PMID: 23271651 PMCID: PMC3818247 DOI: 10.1038/ncomms2325] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 11/20/2012] [Indexed: 01/05/2023] Open
Abstract
The mitochondrial calcium uniporter (MCU) is a highly selective channel responsible for mitochondrial Ca2+ uptake. The MCU shapes cytosolic Ca2+ signals, controls mitochondrial ATP production, and is involved in cell death. Here, using direct patch-clamp recording from the inner mitochondrial membrane, we compare MCU activity in mouse heart, skeletal muscle, liver, kidney, and brown fat. Surprisingly, heart mitochondria shows a dramatically lower MCU current density than the other tissues studied. Similarly, in Drosophila flight muscle, MCU activity is barely detectable compared to that in other fly tissues. Because mitochondria occupy up to 40% of the cell volume in highly metabolically active heart and flight muscle, low MCU activity is likely essential to avoid cytosolic Ca2+ sink due to excessive mitochondrial Ca2+ uptake. Simultaneously, low MCU activity may also prevent mitochondrial Ca2+ overload in such active tissues exposed to frequent cytosolic Ca2+ activity.
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Keilhoff G, Ebmeyer U, Schild L. Spontaneous hypothermia is not able to completely counteract cardiac arrest-induced mitochondrial impairment in the rat heart. Neonatology 2013. [PMID: 23208449 DOI: 10.1159/000345224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vijlbrief et al. [Neonatology 2012;102:243-248] reported a beneficial effect of hypothermia on cardiac function after perinatal asphyxia indicated by low levels of B-type natriuretic peptide (BNP). Elevated troponin I plasma levels, however, reflects impairment of cardiomyocytes under hypothermic conditions. The importance of BNP and cardiac troponin I as biomarkers of cardiac dysfunction that may supplement or substitute Doppler echocardiography has been outlined. Using an asphyxia cardiac arrest (ACA) animal model under spontaneous hypothermia, we found a decrease in the activities of NADH-cytochrome c-oxidoreductase and succinate-cytochrome c-oxidoreductase in comparison to normothermic sham-operated controls. This observation indicates the impairment of the respiratory chain of heart mitochondria, which is accompanied by morphological changes in these mitochondria. Changed cardiac troponin I levels and respiratory chain complexes activity represent different but corresponding steps within the process of cardiomyocyte injury. Interestingly, liver and brain mitochondria remained unchanged under this condition. Patients could benefit from the control of mitochondrial function during hypothermic intervention. When indicated, substances could be supplemented that support mitochondrial function, e.g. antioxidative-acting vitamins and ubiquinone.
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Affiliation(s)
- Gerburg Keilhoff
- Institute of Biochemistry and Cell Biology, University of Magdeburg, Magdeburg, Germany.
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Xiao T, Zhang Y, Wang Y, Xu Y, Yu Z, Shen X. Activation of an apoptotic signal transduction pathway involved in the upregulation of calpain and apoptosis-inducing factor in aldosterone-induced primary cultured cardiomyocytes. Food Chem Toxicol 2012; 53:364-70. [PMID: 23266505 DOI: 10.1016/j.fct.2012.12.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 01/12/2023]
Abstract
In this study, aldosterone (ALD)-induced apoptosis of cardiomyocyte was evaluated based on the previous studies, and the roles of calpain signaling were clarified. Primary cultured rat cardiomyocytes were injured by ALD (0.01-10 μM) for varying time periods. Then, the effects of ethylene glycol tetraacetic acid (EGTA) (0.5 mM), calpeptin (2.5 μM), and spironoclactone (10 μM) were evaluated on cardiomyocytes activated by ALD. Cardiomyocytes that were injured by ALD were assayed by the MTT and LDH leakage ratio. Apoptosis was evaluated by a TUNEL assay, annexin V/PI staining, and caspase-3 activity. The expression of cleavage of Bid (tBid), calpain and apoptosis-inducing factor (AIF) was evaluated by western blot analysis. ALD increased calpain expression and caspase-3 activity and promoted Bid cleavage. It also induced the release of AIF from mitochondria into the cytosol. The upregulation of calpain, tBid and caspase-3 activity were further inhibited by treatment with EGTA in the presence of ALD. Additionally, AIF levels in the cytosol decreased due to EGTA but not due to calpeptin. This was also accompanied by a significant decrease in apoptosis. Furthermore, treatment with spironoclactone not only attenuated the pro-apoptotic effect of ALD but reversed the ALD-induced increase of calpain and AIF levels.
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Affiliation(s)
- Tingting Xiao
- Research Division of Pharmacology, Guiyang Medical University, No. 9 Beiing Road, Guiyang 550004, China
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Palty R, Hershfinkel M, Sekler I. Molecular identity and functional properties of the mitochondrial Na+/Ca2+ exchanger. J Biol Chem 2012; 287:31650-7. [PMID: 22822063 DOI: 10.1074/jbc.r112.355867] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial membrane potential that powers the generation of ATP also facilitates mitochondrial Ca(2+) shuttling. This process is fundamental to a wide range of cellular activities, as it regulates ATP production, shapes cytosolic and endoplasmic recticulum Ca(2+) signaling, and determines cell fate. Mitochondrial Ca(2+) transport is mediated primarily by two major transporters: a Ca(2+) uniporter that mediates Ca(2+) uptake and a Na(+)/Ca(2+) exchanger that subsequently extrudes mitochondrial Ca(2+). In this minireview, we focus on the specific role of the mitochondrial Na(+)/Ca(2+) exchanger and describe its ion exchange mechanism, regulation by ions, and putative partner proteins. We discuss the recent molecular identification of the mitochondrial exchanger and how its activity is linked to physiological and pathophysiological processes.
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Affiliation(s)
- Raz Palty
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA. palty35@berkeley
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Lees-Green R, Du P, O'Grady G, Beyder A, Farrugia G, Pullan AJ. Biophysically based modeling of the interstitial cells of cajal: current status and future perspectives. Front Physiol 2011; 2:29. [PMID: 21772822 PMCID: PMC3131535 DOI: 10.3389/fphys.2011.00029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 06/13/2011] [Indexed: 12/29/2022] Open
Abstract
Gastrointestinal motility research is progressing rapidly, leading to significant advances in the last 15 years in understanding the cellular mechanisms underlying motility, following the discovery of the central role played by the interstitial cells of Cajal (ICC). As experimental knowledge of ICC physiology has expanded, biophysically based modeling has become a valuable tool for integrating experimental data, for testing hypotheses on ICC pacemaker mechanisms, and for applications in in silico studies including in multiscale models. This review is focused on the cellular electrophysiology of ICC. Recent evidence from both experimental and modeling domains have called aspects of the existing pacemaker theories into question. Therefore, current experimental knowledge of ICC pacemaker mechanisms is examined in depth, and current theories of ICC pacemaking are evaluated and further developed. Existing biophysically based ICC models and their physiological foundations are then critiqued in light of the recent advances in experimental knowledge, and opportunities to improve these models are identified. The review concludes by examining several potential clinical applications of biophysically based ICC modeling from the subcellular through to the organ level, including ion channelopathies and ICC network degradation.
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Affiliation(s)
- Rachel Lees-Green
- Auckland Bioengineering Institute, The University of Auckland Auckland, New Zealand
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Rasola A, Bernardi P. Mitochondrial permeability transition in Ca(2+)-dependent apoptosis and necrosis. Cell Calcium 2011; 50:222-33. [PMID: 21601280 DOI: 10.1016/j.ceca.2011.04.007] [Citation(s) in RCA: 396] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 04/22/2011] [Accepted: 04/28/2011] [Indexed: 12/25/2022]
Abstract
A variety of stimuli utilize an increase of cytosolic free Ca(2+) concentration as a second messenger to transmit signals, through Ca(2+) release from the endoplasmic reticulum or opening of plasma membrane Ca(2+) channels. Mitochondria contribute to the tight spatiotemporal control of this process by accumulating Ca(2+), thus shaping the return of cytosolic Ca(2+) to resting levels. The rise of mitochondrial matrix free Ca(2+) concentration stimulates oxidative metabolism; yet, in the presence of a variety of sensitizing factors of pathophysiological relevance, the matrix Ca(2+) increase can also lead to opening of the permeability transition pore (PTP), a high conductance inner membrane channel. While transient openings may serve the purpose of providing a fast Ca(2+) release mechanism, persistent PTP opening is followed by deregulated release of matrix Ca(2+), termination of oxidative phosphorylation, matrix swelling with inner membrane unfolding and eventually outer membrane rupture with release of apoptogenic proteins and cell death. Thus, a rise in mitochondrial Ca(2+) can convey both apoptotic and necrotic death signals by inducing opening of the PTP. Understanding the signalling networks that govern changes in mitochondrial free Ca(2+) concentration, their interplay with Ca(2+) signalling in other subcellular compartments, and regulation of PTP has important implications in the fine comprehension of the main biological routines of the cell and in disease pathogenesis.
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Affiliation(s)
- Andrea Rasola
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova, Italy.
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Dittami GM, Rajguru SM, Lasher RA, Hitchcock RW, Rabbitt RD. Intracellular calcium transients evoked by pulsed infrared radiation in neonatal cardiomyocytes. J Physiol 2011; 589:1295-306. [PMID: 21242257 DOI: 10.1113/jphysiol.2010.198804] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Neonatal rat ventricular cardiomyocytes were used to investigate mechanisms underlying transient changes in intracellular free Ca2+ concentration ([Ca2+]i) evoked by pulsed infrared radiation (IR, 1862 nm). Fluorescence confocal microscopy revealed IR-evoked [Ca2+]i events with each IR pulse (3-4 ms pulse⁻¹, 9.1-11.6 J cm⁻² pulse⁻¹). IR-evoked [Ca2+]i events were distinct from the relatively large spontaneous [Ca2+]i transients, with IR-evoked events exhibiting smaller amplitudes (0.88 ΔF/F0 vs. 1.99 ΔF/F0) and shorter time constants (τ =0.64 s vs. 1.19 s, respectively). Both IR-evoked [Ca2+]i events and spontaneous [Ca2+]i transients could be entrained by the IR pulse (0.2-1 pulse s⁻¹), provided the IR dose was sufficient and the radiation was applied directly to the cell. Examination of IR-evoked events during peak spontaneous [Ca2+]i periods revealed a rapid drop in [Ca2+]i, often restoring the baseline [Ca2+]i concentration, followed by a transient increase in [Ca2+]i.Cardiomyocytes were challenged with pharmacological agents to examine potential contributors to the IR-evoked [Ca2+]i events. Three compounds proved to be the most potent, reversible inhibitors: (1) CGP-37157 (20 μM, n =12), an inhibitor of the mitochondrial Na+/Ca2+ exchanger (mNCX), (2) Ruthenium Red (40 μM, n =13), an inhibitor of the mitochondrial Ca2+ uniporter (mCU), and (3) 2-aminoethoxydiphenylborane (10 μM, n =6), an IP3 channel antagonist. Ryanodine blocked the spontaneous [Ca2+]i transients but did not alter the IR-evoked events in the same cells. This pharmacological array implicates mitochondria as the major intracellular store of Ca2+ involved in IR-evoked responses reported here. Results support the hypothesis that 1862 nm pulsed IR modulates mitochondrial Ca2+ transport primarily through actions on mCU and mNCX.
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Affiliation(s)
- Gregory M Dittami
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA.
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