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Stevens TL, Cohen HM, Garbincius JF, Elrod JW. Mitochondrial calcium uniporter channel gatekeeping in cardiovascular disease. NATURE CARDIOVASCULAR RESEARCH 2024; 3:500-514. [PMID: 39185387 PMCID: PMC11343476 DOI: 10.1038/s44161-024-00463-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 03/18/2024] [Indexed: 08/27/2024]
Abstract
The mitochondrial calcium (mCa2+) uniporter channel (mtCU) resides at the inner mitochondrial membrane and is required for Ca2+ to enter the mitochondrial matrix. The mtCU is essential for cellular function, as mCa2+ regulates metabolism, bioenergetics, signaling pathways and cell death. mCa2+ uptake is primarily regulated by the MICU family (MICU1, MICU2, MICU3), EF-hand-containing Ca2+-sensing proteins, which respond to cytosolic Ca2+ concentrations to modulate mtCU activity. Considering that mitochondrial function and Ca2+ signaling are ubiquitously disrupted in cardiovascular disease, mtCU function has been a hot area of investigation for the last decade. Here we provide an in-depth review of MICU-mediated regulation of mtCU structure and function, as well as potential mtCU-independent functions of these proteins. We detail their role in cardiac physiology and cardiovascular disease by highlighting the phenotypes of different mutant animal models, with an emphasis on therapeutic potential and targets of interest in this pathway.
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Affiliation(s)
- Tyler L. Stevens
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Henry M. Cohen
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Joanne F. Garbincius
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - John W. Elrod
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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Ghosheh M, Ehrlich A, Ioannidis K, Ayyash M, Goldfracht I, Cohen M, Fischer A, Mintz Y, Gepstein L, Nahmias Y. Electro-metabolic coupling in multi-chambered vascularized human cardiac organoids. Nat Biomed Eng 2023; 7:1493-1513. [PMID: 37550423 DOI: 10.1038/s41551-023-01071-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 06/27/2023] [Indexed: 08/09/2023]
Abstract
The study of cardiac physiology is hindered by physiological differences between humans and small-animal models. Here we report the generation of multi-chambered self-paced vascularized human cardiac organoids formed under anisotropic stress and their applicability to the study of cardiac arrhythmia. Sensors embedded in the cardiac organoids enabled the simultaneous measurement of oxygen uptake, extracellular field potentials and cardiac contraction at resolutions higher than 10 Hz. This microphysiological system revealed 1 Hz cardiac respiratory cycles that are coupled to the electrical rather than the mechanical activity of cardiomyocytes. This electro-mitochondrial coupling was driven by mitochondrial calcium oscillations driving respiration cycles. Pharmaceutical or genetic inhibition of this coupling results in arrhythmogenic behaviour. We show that the chemotherapeutic mitoxantrone induces arrhythmia through disruption of this pathway, a process that can be partially reversed by the co-administration of metformin. Our microphysiological cardiac systems may further facilitate the study of the mitochondrial dynamics of cardiac rhythms and advance our understanding of human cardiac physiology.
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Affiliation(s)
- Mohammad Ghosheh
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Avner Ehrlich
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- Tissue Dynamics, LTD, Jerusalem, Israel
| | - Konstantinos Ioannidis
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- Tissue Dynamics, LTD, Jerusalem, Israel
| | - Muneef Ayyash
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Idit Goldfracht
- Sohnis Research Laboratory for Cardiac Electrophysiology and Regenerative Medicine, the Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
| | - Merav Cohen
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Cell and Developmental Biology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Amit Fischer
- Department of Biological Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yoav Mintz
- Department of General Surgery, Hadassah Hebrew University Medical Center, Jerusalem, Israel
- Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lior Gepstein
- Sohnis Research Laboratory for Cardiac Electrophysiology and Regenerative Medicine, the Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
- Cardiology Department, Rambam Health Care Campus, Haifa, Israel
| | - Yaakov Nahmias
- Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel.
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel.
- Tissue Dynamics, LTD, Jerusalem, Israel.
- Department of Cell and Developmental Biology, The Hebrew University of Jerusalem, Jerusalem, Israel.
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Dey S, Joshi P, O'Rourke B, Estes S, DeMazumder D. Cardiac sympathetic denervation prevents sudden cardiac arrest and improves cardiac function by enhancing mitochondrial-antioxidant capacity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.29.526082. [PMID: 36778270 PMCID: PMC9915471 DOI: 10.1101/2023.01.29.526082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
RATIONALE Sudden cardiac arrest (SCA) and heart failure (HF) are leading causes of death. The underlying mechanisms are incompletely understood, limiting the design of new therapies. Whereas most autonomic modulation therapies have not shown clear benefit in HF patients, growing evidence indicates cardiac sympathetic denervation (CSD) exerts cardioprotective effects. The underlying molecular and cellular mechanisms remain unexplored. OBJECTIVE Based on the hypothesis that mitochondrial reactive oxygen species (mROS) drive the pathogenesis of HF and SCA, we investigated whether CSD prevents SCA and HF by improving mitochondrial antioxidant capacity and redox balance, to correct impaired Ca2+ handling and repolarization reserve. METHODS AND RESULTS We interrogated CSD-specific responses in pressure-overload HF models with spontaneous SCA using in vivo echocardiographic and electrocardiographic studies and in vitro biochemical and functional studies including ratiometric measures of mROS, Ca2+ and sarcomere dynamics in left ventricular myocytes. Pressure-overloaded HF reduced mitochondrial antioxidant capacity and increased mROS, which impaired β-adrenergic signaling and caused SR Ca2+ leak, reducing SR Ca2+ and increasing diastolic Ca2+, impaired myofilament contraction and further increased the sympathetic stress response. CSD improved contractile function and mitigated mROS-mediated diastolic Ca2+ overload, dispersion of repolarization, triggered activity and SCA by upregulating mitochondrial antioxidant and NADPH-producing enzymes. CONCLUSIONS Our findings support a fundamental role of sympathetic stress-induced downregulation of mROS scavenging enzymes and RyR-leak mediated diastolic Ca2+ overload in HF and SCA pathogenesis that are mitigated by CSD. This first report on the molecular and cellular mechanisms of CSD supports its evaluation in additional high-risk patient groups.
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Polina I, Mishra J, Cypress MW, Landherr M, Valkov N, Chaput I, Nieto B, Mende U, Zhang P, Jhun BS, O-Uchi J. Mitochondrial Ca 2+ uniporter (MCU) variants form plasma-membrane channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551242. [PMID: 37577584 PMCID: PMC10418069 DOI: 10.1101/2023.07.31.551242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
MCU is widely recognized as a responsible gene for encoding a pore-forming subunit of highly mitochondrial-specific and Ca 2+ -selective channel, mitochondrial Ca 2+ uniporter complex (mtCUC). Here, we report a novel short variant derived from the MCU gene (termed MCU-S) which lacks mitochondria-targeted sequence and forms a Ca 2+ - permeable channel outside of mitochondria. MCU-S was ubiquitously expressed in all cell-types/tissues, with particularly high expression in human platelets. MCU-S formed Ca 2+ channels at the plasma membrane, which exhibited similar channel properties to those observed in mtCUC. MCU-S channels at the plasma membrane served as an additional Ca 2+ influx pathway for platelet activation. Our finding is completely distinct from the originally reported MCU gene function and provides novel insights into the molecular basis of MCU variant-dependent cellular Ca 2+ handling.
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Velmurugan S, Liu T, Chen KC, Despa F, O'Rourke B, Despa S. Distinct Effects of Mitochondrial Na +/Ca 2+ Exchanger Inhibition and Ca 2+ Uniporter Activation on Ca 2+ Sparks and Arrhythmogenesis in Diabetic Rats. J Am Heart Assoc 2023; 12:e029997. [PMID: 37421267 PMCID: PMC10382117 DOI: 10.1161/jaha.123.029997] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 05/26/2023] [Indexed: 07/10/2023]
Abstract
Background Mitochondrial dysfunction contributes to the cardiac remodeling triggered by type 2 diabetes (T2D). Mitochondrial Ca2+ concentration ([Ca2+]m) modulates the oxidative state and cytosolic Ca2+ regulation. Thus, we investigated how T2D affects mitochondrial Ca2+ fluxes, the downstream consequences on myocyte function, and the effects of normalizing mitochondrial Ca2+ transport. Methods and Results We compared myocytes/hearts from transgenic rats with late-onset T2D (rats that develop late-onset T2D due to heterozygous expression of human amylin in the pancreatic β-cells [HIP] model) and their nondiabetic wild-type (WT) littermates. [Ca2+]m was significantly lower in myocytes from diabetic HIP rats compared with WT cells. Ca2+ extrusion through the mitochondrial Na+/Ca2+ exchanger (mitoNCX) was elevated in HIP versus WT myocytes, particularly at moderate and high [Ca2+]m, while mitochondrial Ca2+ uptake was diminished. Mitochondrial Na+ concentration was comparable in WT and HIP rat myocytes and remained remarkably stable while manipulating mitoNCX activity. Lower [Ca2+]m was associated with oxidative stress, increased sarcoplasmic reticulum Ca2+ leak in the form of Ca2+ sparks, and mitochondrial dysfunction in T2D hearts. MitoNCX inhibition with CGP-37157 reduced oxidative stress, Ca2+ spark frequency, and stress-induced arrhythmias in HIP rat hearts while having no significant effect in WT rats. In contrast, activation of the mitochondrial Ca2+ uniporter with SB-202190 enhanced spontaneous sarcoplasmic reticulum Ca2+ release and had no significant effect on arrhythmias in both WT and HIP rat hearts. Conclusions [Ca2+]m is reduced in myocytes from rats with T2D due to a combination of exacerbated mitochondrial Ca2+ extrusion through mitoNCX and impaired mitochondrial Ca2+ uptake. Partial mitoNCX inhibition limits sarcoplasmic reticulum Ca2+ leak and arrhythmias in T2D hearts, whereas mitochondrial Ca2+ uniporter activation does not.
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Affiliation(s)
- Sathya Velmurugan
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Ting Liu
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Kuey C. Chen
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Florin Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Brian O'Rourke
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Sanda Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
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Xie A, Kang GJ, Kim EJ, Feng F, Givens SE, Ogle BM, Dudley SC. Lysosomal Ca 2+ flux modulates automaticity in ventricular cardiomyocytes and correlates with arrhythmic risk. PNAS NEXUS 2023; 2:pgad174. [PMID: 37303713 PMCID: PMC10255768 DOI: 10.1093/pnasnexus/pgad174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 05/16/2023] [Indexed: 06/13/2023]
Abstract
Automaticity involves Ca2+ handling at the cell membrane and sarcoplasmic reticulum (SR). Abnormal or acquired automaticity is thought to initiate ventricular arrhythmias associated with myocardial ischemia. Ca2+ flux from mitochondria can influence automaticity, and lysosomes also release Ca2+. Therefore, we tested whether lysosomal Ca2+ flux could influence automaticity. We studied ventricular human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), hiPSC 3D engineered heart tissues (EHTs), and ventricular cardiomyocytes isolated from infarcted mice. Preventing lysosomal Ca2+ cycling reduced automaticity in hiPSC-CMs. Consistent with a lysosomal role in automaticity, activating the transient receptor potential mucolipin channel (TRPML1) enhanced automaticity, and two channel antagonists reduced spontaneous activity. Activation or inhibition of lysosomal transcription factor EB (TFEB) increased or decreased total lysosomes and automaticity, respectively. In adult ischemic cardiomyocytes and hiPSC 3D EHTs, reducing lysosomal Ca2+ release also inhibited automaticity. Finally, TRPML1 was up-regulated in cardiomyopathic patients with ventricular tachycardia (VT) compared with those without VT. In summary, lysosomal Ca2+ handling modulates abnormal automaticity, and reducing lysosomal Ca2+ release may be a clinical strategy for preventing ventricular arrhythmias.
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Affiliation(s)
- An Xie
- Department of Medicine, University of Minnesota, 401 East River Parkway, VCRC 1st Floor, Suite 131, Minneapolis, MN 55455, USA
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
| | - Gyeoung-Jin Kang
- Department of Medicine, University of Minnesota, 401 East River Parkway, VCRC 1st Floor, Suite 131, Minneapolis, MN 55455, USA
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
| | - Eun Ji Kim
- Department of Medicine, University of Minnesota, 401 East River Parkway, VCRC 1st Floor, Suite 131, Minneapolis, MN 55455, USA
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
| | - Feng Feng
- Department of Medicine, University of Minnesota, 401 East River Parkway, VCRC 1st Floor, Suite 131, Minneapolis, MN 55455, USA
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
| | - Sophie E Givens
- Department of Biomedical Engineering, Stem Cell Institute, University of Minnesota, McGuire Translational Research Facility, 2001 6th Street SE, Mail Code 2873, Minneapolis, MN 55455, USA
| | - Brenda M Ogle
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
- Department of Biomedical Engineering, Stem Cell Institute, University of Minnesota, McGuire Translational Research Facility, 2001 6th Street SE, Mail Code 2873, Minneapolis, MN 55455, USA
- Department of Pediatrics, Institute for Engineering in Medicine, University of Minnesota, 420 Delaware Street Southeast, 725 Mayo Memorial Building, MMC 94, Minneapolis, MN 55455, USA
| | - Samuel C Dudley
- Department of Medicine, University of Minnesota, 401 East River Parkway, VCRC 1st Floor, Suite 131, Minneapolis, MN 55455, USA
- Lillehei Heart Institute, University of Minnesota, 2231 6th Street SE, Suite 4-156, Minneapolis, MN 55455, USA
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Fang Z, Liu Z, Tao B, Jiang X. Engeletin mediates antiarrhythmic effects in mice with isoproterenol-induced cardiac remodeling. Biomed Pharmacother 2023; 161:114439. [PMID: 36848751 DOI: 10.1016/j.biopha.2023.114439] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/17/2023] [Accepted: 02/21/2023] [Indexed: 02/27/2023] Open
Abstract
OBJECTIVE Engeletin is a potent natural compound with antioxidant and anti-inflammatory properties. However, its role in cardiac remodeling remains unclear. Herein, the aim of the present study was to explore the effects of engeletin on cardiac structural and electrical remodeling and its underlying mechanism. METHODS and results: A cardiac remodeling mice model using isoproterenol (ISO)-induced myocardial fibrosis was constructed and divided into the following four groups: control group; engeletin group; ISO group; engeletin + ISO group. Our results demonstrated that engeletin alleviated ISO-induced myocardial fibrosis and dysfunction. Moreover, engeletin significantly prolonged the QT and corrected QT (QTc) intervals, effective refractory period (ERP), and action potential duration (APD), and enhanced connexin protein 43 (Cx43) and ion channel expressions, thereby decreasing ventricular fibrillation (VF) susceptibility. Additionally, dihydroethidium staining illustrated that engeletin decreased reactive oxygen species (ROS) production. Of note, engeletin also increased the levels of superoxide dismutase and glutathione and decreased the activity of malondialdehyde and L-Glutathione oxidized. Moreover, engeletin significantly increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Furthermore, in vitro administration of an Nrf2 inhibitor abolished the anti-oxidant properties of engeletin. CONCLUSION Engeletin ameliorated cardiac structural and electrical remodeling, ion channel remodeling, and oxidative stress induced by ISO in mice, thereby reducing VF susceptibility. These effects may be attributed to the anti-oxidant properties of engeletin associated with the Nrf2/HO-1 pathway.
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Affiliation(s)
- Zhao Fang
- Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China; Hubei Key Laboratory of Cardiology, Wuhan, PR China
| | - Zhebo Liu
- Department of Cardiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Bo Tao
- Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China; Hubei Key Laboratory of Cardiology, Wuhan, PR China.
| | - Xuejun Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China; Hubei Key Laboratory of Cardiology, Wuhan, PR China.
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Mitochondrial Dysfunction in Cardiac Arrhythmias. Cells 2023; 12:cells12050679. [PMID: 36899814 PMCID: PMC10001005 DOI: 10.3390/cells12050679] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Electrophysiological and structural disruptions in cardiac arrhythmias are closely related to mitochondrial dysfunction. Mitochondria are an organelle generating ATP, thereby satisfying the energy demand of the incessant electrical activity in the heart. In arrhythmias, the homeostatic supply-demand relationship is impaired, which is often accompanied by progressive mitochondrial dysfunction leading to reduced ATP production and elevated reactive oxidative species generation. Furthermore, ion homeostasis, membrane excitability, and cardiac structure can be disrupted through pathological changes in gap junctions and inflammatory signaling, which results in impaired cardiac electrical homeostasis. Herein, we review the electrical and molecular mechanisms of cardiac arrhythmias, with a particular focus on mitochondrial dysfunction in ionic regulation and gap junction action. We provide an update on inherited and acquired mitochondrial dysfunction to explore the pathophysiology of different types of arrhythmias. In addition, we highlight the role of mitochondria in bradyarrhythmia, including sinus node dysfunction and atrioventricular node dysfunction. Finally, we discuss how confounding factors, such as aging, gut microbiome, cardiac reperfusion injury, and electrical stimulation, modulate mitochondrial function and cause tachyarrhythmia.
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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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Xie A, Liu H, Kang GJ, Feng F, Dudley SC. Reduced sarcoplasmic reticulum Ca 2+ pump activity is antiarrhythmic in ischemic cardiomyopathy. Heart Rhythm 2022; 19:2107-2114. [PMID: 36028211 DOI: 10.1016/j.hrthm.2022.08.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/26/2022] [Accepted: 08/16/2022] [Indexed: 12/14/2022]
Abstract
BACKGROUND We have described an arrhythmic mechanism seen only in cardiomyopathy that involves increased mitochondrial Ca2+ handling and selective transfer of Ca2+ to the sarcoplasmic reticulum (SR). Modeling suggested that mitochondrial Ca2+ transfer to the SR via type 2a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) is a crucial element of this arrhythmic mechanism. OBJECTIVE We tested the role of SERCA2a in arrhythmias during ischemic cardiomyopathy. METHODS Myocardial infarction (MI) was induced in wild-type (Wt) and SERCA2a heterozygous knockdown (SERCA+/-) mice. RESULTS Compared with Wt MI mice, SERCA2a heterozygous knockdown (SERCA+/-) MI mice had a substantially lower mortality after 3 weeks of MI without a significant change in MI area. Aside from a significant delay of the cytoplasmic Ca2+ transient decay existed in SERCA+/- compared with Wt, SERCA+/- did not affect cardiac systolic and diastolic function at the whole organ or single cell levels either before or after MI. After MI, SERCA+/- mice had reduced SERCA2a expression in the MI border zone compared with Wt MI mice. SERCA+/- mice had significantly decreased corrected QT intervals and less ventricular tachycardia compared with Wt MI mice. SERCA+/- cardiomyocytes from MI mice showed a reduced action potential duration and reduced triggered activity compared with Wt MI cardiomyocytes. Reduction in arrhythmic risk was accompanied by reduced diastolic SR Ca2+ sparks, reduced SR Ca2+ content, reduced oxidized ryanodine receptor, and increased calsequestrin 2 in SERCA+/- MI mice. CONCLUSION SERCA2a knockdown was antiarrhythmic after MI without affecting overall systolic performance. Possible antiarrhythmic mechanisms included reduced SR free Ca2+ and reduced diastolic SR Ca2+ release.
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Affiliation(s)
- An Xie
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | - Hong Liu
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | - Gyeoung-Jin Kang
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | - Feng Feng
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota
| | - Samuel C Dudley
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota.
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Qu Z, Yan D, Song Z. Modeling Calcium Cycling in the Heart: Progress, Pitfalls, and Challenges. Biomolecules 2022; 12:1686. [PMID: 36421700 PMCID: PMC9687412 DOI: 10.3390/biom12111686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Intracellular calcium (Ca) cycling in the heart plays key roles in excitation-contraction coupling and arrhythmogenesis. In cardiac myocytes, the Ca release channels, i.e., the ryanodine receptors (RyRs), are clustered in the sarcoplasmic reticulum membrane, forming Ca release units (CRUs). The RyRs in a CRU act collectively to give rise to discrete Ca release events, called Ca sparks. A cell contains hundreds to thousands of CRUs, diffusively coupled via Ca to form a CRU network. A rich spectrum of spatiotemporal Ca dynamics is observed in cardiac myocytes, including Ca sparks, spark clusters, mini-waves, persistent whole-cell waves, and oscillations. Models of different temporal and spatial scales have been developed to investigate these dynamics. Due to the complexities of the CRU network and the spatiotemporal Ca dynamics, it is challenging to model the Ca cycling dynamics in the cardiac system, particularly at the tissue sales. In this article, we review the progress of modeling of Ca cycling in cardiac systems from single RyRs to the tissue scale, the pros and cons of the current models and different modeling approaches, and the challenges to be tackled in the future.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, A2-237 CHS, 650 Charles E. Young Drive South, Los Angeles, CA 90095, USA
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Dasen Yan
- Peng Cheng Laboratory, Shenzhen 518066, China
| | - Zhen Song
- Peng Cheng Laboratory, Shenzhen 518066, China
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12
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Oost LJ, Tack CJ, de Baaij JHF. Hypomagnesemia and Cardiovascular Risk in Type 2 Diabetes. Endocr Rev 2022; 44:357-378. [PMID: 36346820 PMCID: PMC10166267 DOI: 10.1210/endrev/bnac028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/22/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Hypomagnesemia is tenfold more common in individuals with type 2 diabetes (T2D), compared to the healthy population. Factors that are involved in this high prevalence are low Mg2+ intake, gut microbiome composition, medication use and presumably genetics. Hypomagnesemia is associated with insulin resistance, which subsequently increases the risk to develop T2D or deteriorates glycaemic control in existing diabetes. Mg2+ supplementation decreases T2D associated features like dyslipidaemia and inflammation; which are important risk factors for cardiovascular disease (CVD). Epidemiological studies have shown an inverse association between serum Mg2+ and the risk to develop heart failure (HF), atrial fibrillation (AF) and microvascular disease in T2D. The potential protective effect of Mg2+ on HF and AF may be explained by reduced oxidative stress, fibrosis and electrical remodeling in the heart. In microvascular disease, Mg2+ reduces the detrimental effects of hyperglycemia and improves endothelial dysfunction. Though, clinical studies assessing the effect of long-term Mg2+ supplementation on CVD incidents are lacking and gaps remain on how Mg2+ may reduce CVD risk in T2D. Despite the high prevalence of hypomagnesemia in people with T2D, routine screening of Mg2+ deficiency to provide Mg2+ supplementation when needed is not implemented in clinical care as sufficient clinical evidence is lacking. In conclusion, hypomagnesemia is common in people with T2D and is both involved as cause, probably through molecular mechanisms leading to insulin resistance, and consequence and is prospectively associated with development of HF, AF and microvascular complications. Whether long-term supplementation of Mg2+ is beneficial, however, remains to be determined.
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Affiliation(s)
- Lynette J Oost
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cees J Tack
- Department of Internal Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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13
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Zhao M, Han M, Liang L, Song Q, Li X, Du Y, Hu D, Cheng Y, Wang QK, Ke T. Mog1 deficiency promotes cardiac contractile dysfunction and isoproterenol-induced arrhythmias associated with cardiac fibrosis and Cx43 remodeling. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166429. [PMID: 35533905 DOI: 10.1016/j.bbadis.2022.166429] [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: 02/08/2022] [Revised: 04/21/2022] [Accepted: 05/02/2022] [Indexed: 10/18/2022]
Abstract
Our earlier studies identified MOG1 as a Nav1.5-binding protein that promotes Nav1.5 intracellular trafficking to plasma membranes. Genetic studies have identified MOG1 variants responsible for cardiac arrhythmias. However, the physiological functions of MOG1 in vivo remain incompletely characterized. In this study, we generated Mog1 knockout (Mog1-/-) mice. Mog1-/- mice did not develop spontaneous arrhythmias at the baseline, but exhibited a prolongation of QRS duration. Mog1-/- mice treated with isoproterenol (ISO), but not with flecainide, exhibited an increased risk of arrhythmias and even sudden death. Mog1-/- mice had normal cardiac morphology, however, LV systolic dysfunction was identified and associated with an increase in ventricular fibrosis. Whole-cell patch-clamping and Western blotting analysis clearly demonstrated the normal cardiac expression and function of Nav1.5 in Mog1-/- mice. Further RNA-seq and iTRAQ analysis identified critical pathways and genes, including extracellular matrix (Mmp2), gap junction (Gja1), and mitochondrial components that were dysregulated in Mog1-/- mice. RT-qPCR, Western blotting, and immunofluorescence assays revealed reduced cardiac expression of Gja1 in Mog1-/- mice. Dye transfer assays confirmed impairment of gap-junction function; Cx43 gap-junction enhancer ZP123 decreased arrhythmia inducibility in ISO-treated Mog1-/- mice. Transmission electron microscopy analysis revealed abnormal sarcomere ultrastructure and altered mitochondrial morphology in Mog1-/- mice. Mitochondrial dynamics was found to be disturbed, and associated with a trend toward increased mitochondrial fusion in Mog1-/- mice. Meanwhile, the level of ATP supply was increased in the hearts of Mog1-/- mice. These results indicate that MOG1 plays an important role in cardiac electrophysiology and cardiac contractile function.
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Affiliation(s)
- Miao Zhao
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China
| | - Meng Han
- Hubei Provincial Key Laboratory of Occurrence and Intervention of Kidney Diseases, Medical College, Hubei Polytechnic University, Huangshi, Hubei Province, PR China
| | - Lina Liang
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China
| | - Qixue Song
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 518055 Shenzhen, PR China
| | - Xia Li
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China
| | - Yimei Du
- Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, PR China
| | - Dongping Hu
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China
| | - Yu Cheng
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China
| | - Qing K Wang
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China.
| | - Tie Ke
- Center for Human Genome Research, The Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, 430074, Hubei Province, PR China.
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14
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Mitochondrial Ca 2+ Homeostasis: Emerging Roles and Clinical Significance in Cardiac Remodeling. Int J Mol Sci 2022; 23:ijms23063025. [PMID: 35328444 PMCID: PMC8954803 DOI: 10.3390/ijms23063025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondria are the sites of oxidative metabolism in eukaryotes where the metabolites of sugars, fats, and amino acids are oxidized to harvest energy. Notably, mitochondria store Ca2+ and work in synergy with organelles such as the endoplasmic reticulum and extracellular matrix to control the dynamic balance of Ca2+ concentration in cells. Mitochondria are the vital organelles in heart tissue. Mitochondrial Ca2+ homeostasis is particularly important for maintaining the physiological and pathological mechanisms of the heart. Mitochondrial Ca2+ homeostasis plays a key role in the regulation of cardiac energy metabolism, mechanisms of death, oxygen free radical production, and autophagy. The imbalance of mitochondrial Ca2+ balance is closely associated with cardiac remodeling. The mitochondrial Ca2+ uniporter (mtCU) protein complex is responsible for the uptake and release of mitochondrial Ca2+ and regulation of Ca2+ homeostasis in mitochondria and consequently, in cells. This review summarizes the mechanisms of mitochondrial Ca2+ homeostasis in physiological and pathological cardiac remodeling and the regulatory effects of the mitochondrial calcium regulatory complex on cardiac energy metabolism, cell death, and autophagy, and also provides the theoretical basis for mitochondrial Ca2+ as a novel target for the treatment of cardiovascular diseases.
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15
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Colman MA, Alvarez-Lacalle E, Echebarria B, Sato D, Sutanto H, Heijman J. Multi-Scale Computational Modeling of Spatial Calcium Handling From Nanodomain to Whole-Heart: Overview and Perspectives. Front Physiol 2022; 13:836622. [PMID: 35370783 PMCID: PMC8964409 DOI: 10.3389/fphys.2022.836622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Regulation of intracellular calcium is a critical component of cardiac electrophysiology and excitation-contraction coupling. The calcium spark, the fundamental element of the intracellular calcium transient, is initiated in specialized nanodomains which co-locate the ryanodine receptors and L-type calcium channels. However, calcium homeostasis is ultimately regulated at the cellular scale, by the interaction of spatially separated but diffusively coupled nanodomains with other sub-cellular and surface-membrane calcium transport channels with strong non-linear interactions; and cardiac electrophysiology and arrhythmia mechanisms are ultimately tissue-scale phenomena, regulated by the interaction of a heterogeneous population of coupled myocytes. Recent advances in imaging modalities and image-analysis are enabling the super-resolution reconstruction of the structures responsible for regulating calcium homeostasis, including the internal structure of nanodomains themselves. Extrapolating functional and imaging data from the nanodomain to the whole-heart is non-trivial, yet essential for translational insight into disease mechanisms. Computational modeling has important roles to play in relating structural and functional data at the sub-cellular scale and translating data across the scales. This review covers recent methodological advances that enable image-based modeling of the single nanodomain and whole cardiomyocyte, as well as the development of multi-scale simulation approaches to integrate data from nanometer to whole-heart. Firstly, methods to overcome the computational challenges of simulating spatial calcium dynamics in the nanodomain are discussed, including image-based modeling at this scale. Then, recent whole-cell models, capable of capturing a range of different structures (such as the T-system and mitochondria) and cellular heterogeneity/variability are discussed at two different levels of discretization. Novel methods to integrate the models and data across the scales and simulate stochastic dynamics in tissue-scale models are then discussed, enabling elucidation of the mechanisms by which nanodomain remodeling underlies arrhythmia and contractile dysfunction. Perspectives on model differences and future directions are provided throughout.
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Affiliation(s)
- Michael A. Colman
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Blas Echebarria
- Departament de Fisica, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Daisuke Sato
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Henry Sutanto
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, NY, United States
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
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16
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Cevey ÁC, Mascolo PD, Penas FN, Pieralisi AV, Sequeyra AS, Mirkin GA, Goren NB. Benznidazole Anti-Inflammatory Effects in Murine Cardiomyocytes and Macrophages Are Mediated by Class I PI3Kδ. Front Immunol 2021; 12:782891. [PMID: 34925364 PMCID: PMC8675942 DOI: 10.3389/fimmu.2021.782891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
Benznidazole (Bzl), the drug of choice in many countries for the treatment of Chagas disease, leads to parasite clearance in the early stages of infection and contributes to immunomodulation. In addition to its parasiticidal effect, Bzl inhibits the NF-κB pathway. In this regard, we have previously described that this occurs through IL-10/STAT3/SOCS3 pathway. PI3K pathway is involved in the regulation of the immune system by inhibiting NF-κB pathway through STAT3. In this work, the participation of PI3K in the immunomodulatory effects of Bzl in cardiac and immune cells, the main targets of Chagas disease, was further studied. For that, we use a murine primary cardiomyocyte culture and a monocyte/macrophage cell line (RAW 264.7), stimulated with LPS in presence of LY294002, an inhibitor of PI3K. Under these conditions, Bzl could neither increase SOCS3 expression nor inhibit the NOS2 mRNA expression and the release of NOx, both in cardiomyocytes and macrophages. Macrophages are crucial in the development of Chronic Chagas Cardiomyopathy. Thus, to deepen our understanding of how Bzl acts, the expression profile of M1-M2 macrophage markers was evaluated. Bzl inhibited the release of NOx (M1 marker) and increased the expression of Arginase I (M2 marker) and a negative correlation was found between them. Besides, LPS increased the expression of pro-inflammatory cytokines. Bzl treatment not only inhibited this effect but also increased the expression of typical M2-macrophage markers like Mannose Receptor, TGF-β, and VEGF-A. Moreover, Bzl increased the expression of PPAR-γ and PPAR-α, known as key regulators of macrophage polarization. PI3K directly regulates M1-to-M2 macrophage polarization. Since p110δ, catalytic subunit of PI3Kδ, is highly expressed in immune cells, experiments were carried out in presence of CAL-101, a specific inhibitor of this subunit. Under this condition, Bzl could neither increase SOCS3 expression nor inhibit NF-κB pathway. Moreover, Bzl not only failed to inhibit the expression of pro-inflammatory cytokines (M1 markers) but also could not increase M2 markers. Taken together these results demonstrate, for the first time, that the anti-inflammatory effect of Bzl depends on PI3K activity in a cell line of murine macrophages and in primary culture of neonatal cardiomyocytes. Furthermore, Bzl-mediated increase expression of M2-macrophage markers involves the participation of the p110δ catalytic subunit of PI3Kδ.
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Affiliation(s)
- Ágata C Cevey
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Buenos Aires, Argentina.,CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
| | - Paula D Mascolo
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
| | - Federico N Penas
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Buenos Aires, Argentina.,CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
| | - Azul V Pieralisi
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
| | - Aldana S Sequeyra
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
| | - Gerardo A Mirkin
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Buenos Aires, Argentina.,CONICET, Universidad de Buenos Aires, Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM), Buenos Aires, Argentina
| | - Nora B Goren
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Microbiología, Parasitología e Inmunología, Buenos Aires, Argentina.,CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Buenos Aires, Argentina
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17
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Pandey V, Xie LH, Qu Z, Song Z. Mitochondrial Contributions in the Genesis of Delayed Afterdepolarizations in Ventricular Myocytes. Front Physiol 2021; 12:744023. [PMID: 34721066 PMCID: PMC8551757 DOI: 10.3389/fphys.2021.744023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/02/2021] [Indexed: 11/17/2022] Open
Abstract
Mitochondria fulfill the cell's energy demand and affect the intracellular calcium (Ca2+) dynamics via direct Ca2+ exchange, the redox effect of reactive oxygen species (ROS) on Ca2+ handling proteins, and other signaling pathways. Recent experimental evidence indicates that mitochondrial depolarization promotes arrhythmogenic delayed afterdepolarizations (DADs) in cardiac myocytes. However, the nonlinear interactions among the Ca2+ signaling pathways, ROS, and oxidized Ca2+/calmodulin-dependent protein kinase II (CaMKII) pathways make it difficult to reveal the mechanisms. Here, we use a recently developed spatiotemporal ventricular myocyte computer model, which consists of a 3-dimensional network of Ca2+ release units (CRUs) intertwined with mitochondria and integrates mitochondrial Ca2+ signaling and other complex signaling pathways, to study the mitochondrial regulation of DADs. With a systematic investigation of the synergistic or competing factors that affect the occurrence of Ca2+ waves and DADs during mitochondrial depolarization, we find that the direct redox effect of ROS on ryanodine receptors (RyRs) plays a critical role in promoting Ca2+ waves and DADs under the acute effect of mitochondrial depolarization. Furthermore, the upregulation of mitochondrial Ca2+ uniporter can promote DADs through Ca2+-dependent opening of mitochondrial permeability transition pores (mPTPs). Also, due to much slower dynamics than Ca2+ cycling and ROS, oxidized CaMKII activation and the cytosolic ATP do not appear to significantly impact the genesis of DADs during the acute phase of mitochondrial depolarization. However, under chronic conditions, ATP depletion suppresses and enhanced CaMKII activation promotes Ca2+ waves and DADs.
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Affiliation(s)
- Vikas Pandey
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Peng Cheng Laboratory, Shenzhen, China
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18
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Hamilton S, Terentyeva R, Perger F, Hernández Orengo B, Martin B, Gorr MW, Belevych AE, Clements RT, Györke S, Terentyev D. MCU overexpression evokes disparate dose-dependent effects on mito-ROS and spontaneous Ca 2+ release in hypertrophic rat cardiomyocytes. Am J Physiol Heart Circ Physiol 2021; 321:H615-H632. [PMID: 34415186 PMCID: PMC8794228 DOI: 10.1152/ajpheart.00126.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 08/13/2021] [Accepted: 08/13/2021] [Indexed: 12/11/2022]
Abstract
Cardiac dysfunction in heart failure (HF) and diabetic cardiomyopathy (DCM) is associated with aberrant intracellular Ca2+ handling and impaired mitochondrial function accompanied with reduced mitochondrial calcium concentration (mito-[Ca2+]). Pharmacological or genetic facilitation of mito-Ca2+ uptake was shown to restore Ca2+ transient amplitude in DCM and HF, improving contractility. However, recent reports suggest that pharmacological enhancement of mito-Ca2+ uptake can exacerbate ryanodine receptor-mediated spontaneous sarcoplasmic reticulum (SR) Ca2+ release in ventricular myocytes (VMs) from diseased animals, increasing propensity to stress-induced ventricular tachyarrhythmia. To test whether chronic recovery of mito-[Ca2+] restores systolic Ca2+ release without adverse effects in diastole, we overexpressed mitochondrial Ca2+ uniporter (MCU) in VMs from male rat hearts with hypertrophy induced by thoracic aortic banding (TAB). Measurement of mito-[Ca2+] using genetic probe mtRCamp1h revealed that mito-[Ca2+] in TAB VMs paced at 2 Hz under β-adrenergic stimulation is lower compared with shams. Adenoviral 2.5-fold MCU overexpression in TAB VMs fully restored mito-[Ca2+]. However, it failed to improve cytosolic Ca2+ handling and reduce proarrhythmic spontaneous Ca2+ waves. Furthermore, mitochondrial-targeted genetic probes MLS-HyPer7 and OMM-HyPer revealed a significant increase in emission of reactive oxygen species (ROS) in TAB VMs with 2.5-fold MCU overexpression. Conversely, 1.5-fold MCU overexpression in TABs, that led to partial restoration of mito-[Ca2+], reduced mitochondria-derived reactive oxygen species (mito-ROS) and spontaneous Ca2+ waves. Our findings emphasize the key role of elevated mito-ROS in disease-related proarrhythmic Ca2+ mishandling. These data establish nonlinear mito-[Ca2+]/mito-ROS relationship, whereby partial restoration of mito-[Ca2+] in diseased VMs is protective, whereas further enhancement of MCU-mediated Ca2+ uptake exacerbates damaging mito-ROS emission.NEW & NOTEWORTHY Defective intracellular Ca2+ homeostasis and aberrant mitochondrial function are common features in cardiac disease. Here, we directly compared potential benefits of mito-ROS scavenging and restoration of mito-Ca2+ uptake by overexpressing MCU in ventricular myocytes from hypertrophic rat hearts. Experiments using novel mito-ROS and Ca2+ biosensors demonstrated that mito-ROS scavenging rescued both cytosolic and mito-Ca2+ homeostasis, whereas moderate and high MCU overexpression demonstrated disparate effects on mito-ROS emission, with only a moderate increase in MCU being beneficial.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Animals
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Arrhythmias, Cardiac/physiopathology
- Biosensing Techniques
- Calcium/metabolism
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Signaling/drug effects
- Cells, Cultured
- Disease Models, Animal
- Heart Rate
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Male
- Microscopy, Confocal
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/genetics
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Myocardial Contraction
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Rats, Sprague-Dawley
- Reactive Oxygen Species/metabolism
- Up-Regulation
- Ventricular Function, Left
- Ventricular Remodeling
- Rats
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Affiliation(s)
- Shanna Hamilton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Radmila Terentyeva
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Fruzsina Perger
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Benjamín Hernández Orengo
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Benjamin Martin
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Matthew W Gorr
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- College of Nursing, The Ohio State University, Columbus, Ohio
| | - Andriy E Belevych
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Richard T Clements
- Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island
| | - Sandor Györke
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
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19
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Joseph LC, Reyes MV, Homan EA, Gowen B, Avula UMR, Goulbourne CN, Wan EY, Elrod JW, Morrow JP. The mitochondrial calcium uniporter promotes arrhythmias caused by high-fat diet. Sci Rep 2021; 11:17808. [PMID: 34497331 PMCID: PMC8426388 DOI: 10.1038/s41598-021-97449-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 08/13/2021] [Indexed: 12/16/2022] Open
Abstract
Obesity and diabetes increase the risk of arrhythmia and sudden cardiac death. However, the molecular mechanisms of arrhythmia caused by metabolic abnormalities are not well understood. We hypothesized that mitochondrial dysfunction caused by high fat diet (HFD) promotes ventricular arrhythmia. Based on our previous work showing that saturated fat causes calcium handling abnormalities in cardiomyocytes, we hypothesized that mitochondrial calcium uptake contributes to HFD-induced mitochondrial dysfunction and arrhythmic events. For experiments, we used mice with conditional cardiac-specific deletion of the mitochondrial calcium uniporter (Mcu), which is required for mitochondrial calcium uptake, and littermate controls. Mice were used for in vivo heart rhythm monitoring, perfused heart experiments, and isolated cardiomyocyte experiments. MCU KO mice are protected from HFD-induced long QT, inducible ventricular tachycardia, and abnormal ventricular repolarization. Abnormal repolarization may be due, at least in part, to a reduction in protein levels of voltage gated potassium channels. Furthermore, isolated cardiomyocytes from MCU KO mice exposed to saturated fat are protected from increased reactive oxygen species (ROS), mitochondrial dysfunction, and abnormal calcium handling. Activation of calmodulin-dependent protein kinase (CaMKII) corresponds with the increase in arrhythmias in vivo. Additional experiments showed that CaMKII inhibition protects cardiomyocytes from the mitochondrial dysfunction caused by saturated fat. Hearts from transgenic CaMKII inhibitor mice were protected from inducible ventricular tachycardia after HFD. These studies identify mitochondrial dysfunction caused by calcium overload as a key mechanism of arrhythmia during HFD. This work indicates that MCU and CaMKII could be therapeutic targets for arrhythmia caused by metabolic abnormalities.
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Affiliation(s)
- Leroy C Joseph
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
| | - Michael V Reyes
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
| | - Edwin A Homan
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
| | - Blake Gowen
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
| | - Uma Mahesh R Avula
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
- Division of Nephrology, Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Chris N Goulbourne
- Center for Dementia Research, Nathan S. Kline Institute, Orangeburg, NY, USA
| | - Elaine Y Wan
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA
| | - John W Elrod
- Lewis Katz School of Medicine at Temple University, 3500 N Broad St, MERB 949, Philadelphia, PA, USA
| | - John P Morrow
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY, 10032, USA.
- College of Physicians and Surgeons of Columbia University, PH10-203, 650 W 168th Street, New York, NY, 10032, USA.
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20
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The Role of Mitochondrial Dysfunction in Atrial Fibrillation: Translation to Druggable Target and Biomarker Discovery. Int J Mol Sci 2021; 22:ijms22168463. [PMID: 34445167 PMCID: PMC8395135 DOI: 10.3390/ijms22168463] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 01/02/2023] Open
Abstract
Atrial fibrillation (AF) is the most prevalent and progressive cardiac arrhythmia worldwide and is associated with serious complications such as heart failure and ischemic stroke. Current treatment modalities attenuate AF symptoms and are only moderately effective in halting the arrhythmia. Therefore, there is an urgent need to dissect molecular mechanisms that drive AF. As AF is characterized by a rapid atrial activation rate, which requires a high energy metabolism, a role of mitochondrial dysfunction in AF pathophysiology is plausible. It is well known that mitochondria play a central role in cardiomyocyte function, as they produce energy to support the mechanical and electrical function of the heart. Details on the molecular mechanisms underlying mitochondrial dysfunction are increasingly being uncovered as a contributing factor in the loss of cardiomyocyte function and AF. Considering the high prevalence of AF, investigating the role of mitochondrial impairment in AF may guide the path towards new therapeutic and diagnostic targets. In this review, the latest evidence on the role of mitochondria dysfunction in AF is presented. We highlight the key modulators of mitochondrial dysfunction that drive AF and discuss whether they represent potential targets for therapeutic interventions and diagnostics in clinical AF.
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21
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Hamilton S, Terentyeva R, Clements RT, Belevych AE, Terentyev D. Sarcoplasmic reticulum-mitochondria communication; implications for cardiac arrhythmia. J Mol Cell Cardiol 2021; 156:105-113. [PMID: 33857485 DOI: 10.1016/j.yjmcc.2021.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/15/2021] [Accepted: 04/05/2021] [Indexed: 12/11/2022]
Abstract
Sudden cardiac death due to ventricular tachyarrhythmias remains the major cause of mortality in the world. Heart failure, diabetic cardiomyopathy, old age-related cardiac dysfunction and inherited disorders are associated with enhanced propensity to malignant cardiac arrhythmias. Both defective mitochondrial function and abnormal intracellular Ca2+ homeostasis have been established as the key contributing factors in the pathophysiology and arrhythmogenesis in these conditions. This article reviews current advances in understanding of bidirectional control of ryanodine receptor-mediated sarcoplasmic reticulum Ca2+ release and mitochondrial function, and how defects in crosstalk between these two organelles increase arrhythmic risk in cardiac disease.
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Affiliation(s)
- Shanna Hamilton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, United States of America
| | - Radmila Terentyeva
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, United States of America
| | - Richard T Clements
- Biomedical & Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, United States of America
| | - Andriy E Belevych
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, United States of America
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, United States of America.
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22
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Liu T, Yang N, Sidor A, O'Rourke B. MCU Overexpression Rescues Inotropy and Reverses Heart Failure by Reducing SR Ca 2+ Leak. Circ Res 2021; 128:1191-1204. [PMID: 33522833 DOI: 10.1161/circresaha.120.318562] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Ting Liu
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD
| | - Ni Yang
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD
| | - Agnieszka Sidor
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD
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23
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Salazar-Ramírez F, Ramos-Mondragón R, García-Rivas G. Mitochondrial and Sarcoplasmic Reticulum Interconnection in Cardiac Arrhythmia. Front Cell Dev Biol 2021; 8:623381. [PMID: 33585462 PMCID: PMC7876262 DOI: 10.3389/fcell.2020.623381] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/30/2020] [Indexed: 12/31/2022] Open
Abstract
Ca2+ plays a pivotal role in mitochondrial energy production, contraction, and apoptosis. Mitochondrial Ca2+-targeted fluorescent probes have demonstrated that mitochondria Ca2+ transients are synchronized with Ca2+ fluxes occurring in the sarcoplasmic reticulum (SR). The presence of specialized proteins tethering SR to mitochondria ensures the local Ca2+ flux between these organelles. Furthermore, communication between SR and mitochondria impacts their functionality in a bidirectional manner. Mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniplex is essential for ATP production and controlled reactive oxygen species levels for proper cellular signaling. Conversely, mitochondrial ATP ensures the proper functioning of SR Ca2+-handling proteins, which ensures that mitochondria receive an adequate supply of Ca2+. Recent evidence suggests that altered SR Ca2+ proteins, such as ryanodine receptors and the sarco/endoplasmic reticulum Ca2+ ATPase pump, play an important role in maintaining proper cardiac membrane excitability, which may be initiated and potentiated when mitochondria are dysfunctional. This recognized mitochondrial role offers the opportunity to develop new therapeutic approaches aimed at preventing cardiac arrhythmias in cardiac disease.
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Affiliation(s)
- Felipe Salazar-Ramírez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología y Medicina Cardiovascular, Monterrey, Mexico
| | - Roberto Ramos-Mondragón
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States.,Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Gerardo García-Rivas
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología y Medicina Cardiovascular, Monterrey, Mexico.,TecSalud, Centro de Investigación Biomédica, Hospital Zambrano-Hellion, San Pedro Garza García, Mexico.,TecSalud, Centro de Medicina Funcional, Hospital Zambrano-Hellion, San Pedro Garza García, Mexico
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24
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Pandey V, Xie LH, Qu Z, Song Z. Mitochondrial depolarization promotes calcium alternans: Mechanistic insights from a ventricular myocyte model. PLoS Comput Biol 2021; 17:e1008624. [PMID: 33493168 PMCID: PMC7861552 DOI: 10.1371/journal.pcbi.1008624] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 02/04/2021] [Accepted: 12/10/2020] [Indexed: 01/08/2023] Open
Abstract
Mitochondria are vital organelles inside the cell and contribute to intracellular calcium (Ca2+) dynamics directly and indirectly via calcium exchange, ATP generation, and production of reactive oxygen species (ROS). Arrhythmogenic Ca2+ alternans in cardiac myocytes has been observed in experiments under abnormal mitochondrial depolarization. However, complex signaling pathways and Ca2+ cycling between mitochondria and cytosol make it difficult in experiments to reveal the underlying mechanisms of Ca2+ alternans under abnormal mitochondrial depolarization. In this study, we use a newly developed spatiotemporal ventricular myocyte computer model that integrates mitochondrial Ca2+ cycling and complex signaling pathways to investigate the mechanisms of Ca2+ alternans during mitochondrial depolarization. We find that elevation of ROS in response to mitochondrial depolarization plays a critical role in promoting Ca2+ alternans. Further examination reveals that the redox effect of ROS on ryanodine receptors and sarco/endoplasmic reticulum Ca2+-ATPase synergistically promote alternans. Upregulation of mitochondrial Ca2+ uniporter promotes Ca2+ alternans via Ca2+-dependent mitochondrial permeability transition pore opening. Due to their relatively slow kinetics, oxidized Ca2+/calmodulin-dependent protein kinase II activation and ATP do not play significant roles acutely in the genesis of Ca2+ alternans after mitochondrial depolarization, but their roles can be significant in the long term, mainly through their effects on sarco/endoplasmic reticulum Ca2+-ATPase activity. In conclusion, mitochondrial depolarization promotes Ca2+ alternans acutely via the redox effect of ROS and chronically by ATP reduction. It suppresses Ca2+ alternans chronically through oxidized Ca2+/calmodulin-dependent protein kinase II activation.
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Affiliation(s)
- Vikas Pandey
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Peng Cheng Laboratory, Shenzhen, Guangdong, China
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25
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O'Rourke B, Ashok D, Liu T. Mitochondrial Ca 2+ in heart failure: Not enough or too much? J Mol Cell Cardiol 2020; 151:126-134. [PMID: 33290770 DOI: 10.1016/j.yjmcc.2020.11.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/18/2020] [Accepted: 11/28/2020] [Indexed: 01/04/2023]
Abstract
Ca2+ serves as a ubiquitous second messenger mediating a variety of cellular processes including electrical excitation, contraction, gene expression, secretion, cell death and others. The identification of the molecular components of the mitochondrial Ca2+ influx and efflux pathways has created a resurgent interest in the regulation of mitochondrial Ca2+ balance and its physiological and pathophysiological roles. While the pace of discovery has quickened with the availability of new cellular and animal models, many fundamental questions remain to be answered regarding the regulation and functional impact of mitochondrial Ca2+ in health and disease. This review highlights several experimental observations pertaining to key aspects of mitochondrial Ca2+ homeostasis that remain enigmatic, particularly whether mitochondrial Ca2+ signaling is depressed or excessive in heart failure, which will determine the optimal approach to therapeutic intervention.
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Affiliation(s)
- Brian O'Rourke
- The Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, MD 21205, USA.
| | - Deepthi Ashok
- The Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, MD 21205, USA
| | - Ting Liu
- The Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, MD 21205, USA
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26
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Kang GJ, Xie A, Liu H, Dudley SC. MIR448 antagomir reduces arrhythmic risk after myocardial infarction by upregulating the cardiac sodium channel. JCI Insight 2020; 5:140759. [PMID: 33108349 PMCID: PMC7714400 DOI: 10.1172/jci.insight.140759] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/21/2020] [Indexed: 12/17/2022] Open
Abstract
Cardiac ischemia is associated with arrhythmias; however, effective therapies are currently limited. The cardiac voltage-gated sodium channel α subunit (SCN5A), encoding the Nav1.5 current, plays a key role in the cardiac electrical conduction and arrhythmic risk. Here, we show that hypoxia reduces Nav1.5 through effects on a miR, miR-448. miR-448 expression is increased in ischemic cardiomyopathy. miR-448 has a conserved binding site in 3′-UTR of SCN5A. miR-448 binding to this site suppressed SCN5A expression and sodium currents. Hypoxia-induced HIF-1α and NF-κB were major transcriptional regulators for MIR448. Moreover, hypoxia relieved MIR448 transcriptional suppression by RE1 silencing transcription factor. Therefore, miR-448 inhibition reduced arrhythmic risk after myocardial infarction. Here, we show that ischemia drove miR-448 expression, reduced Nav1.5 current, and increased arrhythmic risk. Arrhythmic risk was improved by preventing Nav1.5 downregulation, suggesting a new approach to antiarrhythmic therapy. Ischemic induction of miR-448 negatively regulates the cardiac sodium channel Nav1.5, and inhibiting miR-448 raises Nav1.5 and reduces arrhythmic risk after myocardial infarction in mice.
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27
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Njegic A, Wilson C, Cartwright EJ. Targeting Ca 2 + Handling Proteins for the Treatment of Heart Failure and Arrhythmias. Front Physiol 2020; 11:1068. [PMID: 33013458 PMCID: PMC7498719 DOI: 10.3389/fphys.2020.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022] Open
Abstract
Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca2+) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca2+ is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca2+ cycling and signaling play a vital role in maintaining Ca2+ homeostasis. Changes to the expression levels and function of Ca2+-channels, pumps and associated intracellular handling proteins contribute to altered Ca2+ homeostasis in CVD. The remodeling of Ca2+-handling proteins therefore results in impaired Ca2+ cycling, Ca2+ leak from the sarcoplasmic reticulum and reduced Ca2+ clearance, all of which contributes to increased intracellular Ca2+. Currently, approved treatments for targeting Ca2+ handling dysfunction in CVD are focused on Ca2+ channel blockers. However, whilst Ca2+ channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca2+ homeostasis, this review will address the molecular changes to proteins associated with both Ca2+-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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Affiliation(s)
- Alexandra Njegic
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom
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28
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Oropeza-Almazán Y, Blatter LA. Mitochondrial calcium uniporter complex activation protects against calcium alternans in atrial myocytes. Am J Physiol Heart Circ Physiol 2020; 319:H873-H881. [PMID: 32857593 DOI: 10.1152/ajpheart.00375.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cardiac alternans, defined as beat-to-beat alternations in action potential duration, cytosolic Ca transient (CaT) amplitude, and cardiac contraction is associated with atrial fibrillation (AF) and sudden cardiac death. At the cellular level, cardiac alternans is linked to abnormal intracellular calcium handling during excitation-contraction coupling. We investigated how pharmacological activation or inhibition of cytosolic Ca sequestration via mitochondrial Ca uptake and mitochondrial Ca retention affects the occurrence of pacing-induced CaT alternans in isolated rabbit atrial myocytes. Cytosolic CaTs were recorded using Fluo-4 fluorescence microscopy. Alternans was quantified as the alternans ratio (AR = 1 - CaTsmall/CaTlarge, where CaTsmall and CaTlarge are the amplitudes of the small and large CaTs of a pair of alternating CaTs). Inhibition of mitochondrial Ca sequestration via mitochondrial Ca uniporter complex (MCUC) with Ru360 enhanced the severity of CaT alternans (AR increase) and lowered the pacing frequency threshold for alternans. In contrast, stimulation of MCUC mediated mitochondrial Ca uptake with spermine-rescued alternans (AR decrease) and increased the alternans pacing threshold. Direct measurement of mitochondrial [Ca] in membrane permeabilized myocytes with Fluo-4 loaded mitochondria revealed that spermine enhanced and accelerated mitochondrial Ca uptake. Stimulation of mitochondrial Ca retention by preventing mitochondrial Ca efflux through the mitochondrial permeability transition pore with cyclosporin A also protected from alternans and increased the alternans pacing threshold. Pharmacological manipulation of MCUC activity did not affect sarcoplasmic reticulum Ca load. Our results suggest that activation of Ca sequestration by mitochondria protects from CaT alternans and could be a potential therapeutic target for cardiac alternans and AF prevention.NEW & NOTEWORTHY This study provides conclusive evidence that mitochondrial Ca uptake and retention protects from Ca alternans, whereas uptake inhibition enhances Ca alternans. The data suggest pharmacological mitochondrial Ca cycling modulation as a potential therapeutic strategy for alternans-related cardiac arrhythmia prevention.
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Affiliation(s)
| | - Lothar A Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois
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29
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Song Z, Xie LH, Weiss JN, Qu Z. A Spatiotemporal Ventricular Myocyte Model Incorporating Mitochondrial Calcium Cycling. Biophys J 2019; 117:2349-2360. [PMID: 31623883 PMCID: PMC6990377 DOI: 10.1016/j.bpj.2019.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/19/2019] [Accepted: 09/09/2019] [Indexed: 12/27/2022] Open
Abstract
Intracellular calcium (Ca2+) cycling dynamics in cardiac myocytes are spatiotemporally generated by stochastic events arising from a spatially distributed network of coupled Ca2+ release units that interact with an intertwined mitochondrial network. In this study, we developed a spatiotemporal ventricular myocyte model that integrates mitochondria-related Ca2+ cycling components into our previously developed ventricular myocyte model consisting of a three-dimensional Ca2+ release unit network. Mathematical formulations of mitochondrial membrane potential, mitochondrial Ca2+ cycling, mitochondrial permeability transition pore stochastic opening and closing, intracellular reactive oxygen species signaling, and oxidized Ca2+/calmodulin-dependent protein kinase II signaling were incorporated into the model. We then used the model to simulate the effects of mitochondrial depolarization on mitochondrial Ca2+ cycling, Ca2+ spark frequency, and Ca2+ amplitude, which agree well with experimental data. We also simulated the effects of the strength of mitochondrial Ca2+ uniporters and their spatial localization on intracellular Ca2+ cycling properties, which substantially affected diastolic and systolic Ca2+ levels in the mitochondria but exhibited only a small effect on sarcoplasmic reticulum and cytosolic Ca2+ levels under normal conditions. We show that mitochondrial depolarization can cause Ca2+ waves and Ca2+ alternans, which agrees with previous experimental observations. We propose that this new, to our knowledge, spatiotemporal ventricular myocyte model, incorporating properties of mitochondrial Ca2+ cycling and reactive-oxygen-species-dependent signaling, will be useful for investigating the effects of mitochondria on intracellular Ca2+ cycling and action potential dynamics in ventricular myocytes.
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Affiliation(s)
- Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, New Jersey
| | - James N Weiss
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
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30
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Tarasova NV, Vishnyakova PA, Logashina YA, Elchaninov AV. Mitochondrial Calcium Uniporter Structure and Function in Different Types of Muscle Tissues in Health and Disease. Int J Mol Sci 2019; 20:ijms20194823. [PMID: 31569359 PMCID: PMC6801532 DOI: 10.3390/ijms20194823] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/12/2019] [Accepted: 09/26/2019] [Indexed: 02/07/2023] Open
Abstract
Calcium ions (Ca2+) influx to mitochondrial matrix is crucial for the life of a cell. Mitochondrial calcium uniporter (mtCU) is a protein complex which consists of the pore-forming subunit (MCU) and several regulatory subunits. MtCU is the main contributor to inward Ca2+ currents through the inner mitochondrial membrane. Extensive investigations of mtCU involvement into normal and pathological molecular pathways started from the moment of discovery of its molecular components. A crucial role of mtCU in the control of these pathways is now recognized in both health and disease. In particular, impairments of mtCU function have been demonstrated for cardiovascular and skeletal muscle-associated pathologies. This review summarizes the current state of knowledge on mtCU structure, regulation, and function in different types of muscle tissues in health and disease.
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Affiliation(s)
- Nadezhda V Tarasova
- Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Trubetskaya str. 8, bld. 2, Moscow 119991, Russia.
| | - Polina A Vishnyakova
- National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov of Ministry of Healthcare of Russian Federation, 4 Oparina Street, Moscow 117997, Russia.
| | - Yulia A Logashina
- Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Trubetskaya str. 8, bld. 2, Moscow 119991, Russia.
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russia.
| | - Andrey V Elchaninov
- National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov of Ministry of Healthcare of Russian Federation, 4 Oparina Street, Moscow 117997, Russia.
- Scientific Research Institute of Human Morphology, 3 Tsurupa Street, Moscow 117418, Russia.
- Peoples' Friendship University of Russia, 6 Miklukho-Maklaya Street, Moscow 117198, Russia.
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31
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Cao JL, Adaniya SM, Cypress MW, Suzuki Y, Kusakari Y, Jhun BS, O-Uchi J. Role of mitochondrial Ca 2+ homeostasis in cardiac muscles. Arch Biochem Biophys 2019; 663:276-287. [PMID: 30684463 PMCID: PMC6469710 DOI: 10.1016/j.abb.2019.01.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/10/2019] [Accepted: 01/22/2019] [Indexed: 12/22/2022]
Abstract
Recent discoveries of the molecular identity of mitochondrial Ca2+ influx/efflux mechanisms have placed mitochondrial Ca2+ transport at center stage in views of cellular regulation in various cell-types/tissues. Indeed, mitochondria in cardiac muscles also possess the molecular components for efficient uptake and extraction of Ca2+. Over the last several years, multiple groups have taken advantage of newly available molecular information about these proteins and applied genetic tools to delineate the precise mechanisms for mitochondrial Ca2+ handling in cardiomyocytes and its contribution to excitation-contraction/metabolism coupling in the heart. Though mitochondrial Ca2+ has been proposed as one of the most crucial secondary messengers in controlling a cardiomyocyte's life and death, the detailed mechanisms of how mitochondrial Ca2+ regulates physiological mitochondrial and cellular functions in cardiac muscles, and how disorders of this mechanism lead to cardiac diseases remain unclear. In this review, we summarize the current controversies and discrepancies regarding cardiac mitochondrial Ca2+ signaling that remain in the field to provide a platform for future discussions and experiments to help close this gap.
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Affiliation(s)
- Jessica L Cao
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, USA; Department of Medicine, Division of Cardiology, The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Stephanie M Adaniya
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, USA; Department of Medicine, Division of Cardiology, The Warren Alpert Medical School of Brown University, Providence, RI, USA; Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Michael W Cypress
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Yuta Suzuki
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Yoichiro Kusakari
- Department of Cell Physiology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Bong Sook Jhun
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Jin O-Uchi
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA.
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32
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Liu M, Jeong EM, Liu H, Xie A, So EY, Shi G, Jeong GE, Zhou A, Dudley SC. Magnesium supplementation improves diabetic mitochondrial and cardiac diastolic function. JCI Insight 2019; 4:123182. [PMID: 30626750 DOI: 10.1172/jci.insight.123182] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/05/2018] [Indexed: 01/11/2023] Open
Abstract
In heart failure and type 2 diabetes mellitus (DM), the majority of patients have hypomagnesemia, and magnesium (Mg) supplementation has improved cardiac function and insulin resistance. Recently, we have shown that DM can cause cardiac diastolic dysfunction (DD). Therefore, we hypothesized that Mg supplementation would improve diastolic function in DM. High-fat diet-induced diabetic mouse hearts showed increased cardiac DD and hypertrophy. Mice with DM showed a significantly increased E/e' ratio (the ratio of transmitral Doppler early filling velocity [E] to tissue Doppler early diastolic mitral annular velocity [e']) in the echocardiogram, left ventricular end diastolic volume (LVEDV), incidence of DD, left ventricular posterior wall thickness in diastole (PWTd), and ratio of heart weight to tibia length (HW/TL) when compared with controls. DM mice also had hypomagnesemia. Ventricular cardiomyocytes isolated from DM mice exhibited decreased mitochondrial ATP production, a 1.7- ± 0.2-fold increase of mitochondrial ROS, depolarization of the mitochondrial membrane potential, and mitochondrial Ca2+ overload. Dietary Mg administration (50 mg/ml in the drinking water) for 6 weeks increased plasma Mg concentration and improved cardiac function. At the cellular level, Mg improved mitochondrial function with increased ATP, decreased mitochondrial ROS and Ca2+ overload, and repolarized mitochondrial membrane potential. In conclusion, Mg supplementation improved mitochondrial function, reduced oxidative stress, and prevented DD in DM.
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Affiliation(s)
- Man Liu
- Division of Cardiology, Department of Medicine, the Lillehei Heart Institute, University of Minnesota at Twin Cities, Minneapolis, Minnesota
| | - Euy-Myoung Jeong
- Cardiovascular Research Center, Lifespan Rhode Island Hospital, Providence, Rhode Island.,The Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Hong Liu
- Division of Cardiology, Department of Medicine, the Lillehei Heart Institute, University of Minnesota at Twin Cities, Minneapolis, Minnesota
| | - An Xie
- Division of Cardiology, Department of Medicine, the Lillehei Heart Institute, University of Minnesota at Twin Cities, Minneapolis, Minnesota
| | - Eui Young So
- Cardiovascular Research Center, Lifespan Rhode Island Hospital, Providence, Rhode Island.,The Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Guangbin Shi
- Cardiovascular Research Center, Lifespan Rhode Island Hospital, Providence, Rhode Island
| | | | - Anyu Zhou
- Cardiovascular Research Center, Lifespan Rhode Island Hospital, Providence, Rhode Island.,The Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Samuel C Dudley
- Division of Cardiology, Department of Medicine, the Lillehei Heart Institute, University of Minnesota at Twin Cities, Minneapolis, Minnesota
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33
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Homan EA, Reyes MV, Hickey KT, Morrow JP. Clinical Overview of Obesity and Diabetes Mellitus as Risk Factors for Atrial Fibrillation and Sudden Cardiac Death. Front Physiol 2019; 9:1847. [PMID: 30666210 PMCID: PMC6330323 DOI: 10.3389/fphys.2018.01847] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 12/07/2018] [Indexed: 12/22/2022] Open
Abstract
The epidemics of obesity and diabetes mellitus are associated with an increased incidence of both atrial fibrillation (AF), the most common sustained arrhythmia in adults, and sudden cardiac death (SCD). Obesity and DM are known to have adverse effects on cardiac structure and function. The pathologic mechanisms are thought to involve cardiac tissue remodeling, metabolic dysregulation, inflammation, and oxidative stress. Clinical data suggest that left atrial size, epicardial fat pad thickness, and other modifiable risk factors such as hypertension, glycemic control, and obstructive sleep apnea may mediate the association with AF. Data from human atrial tissue biopsies demonstrate alterations in atrial lipid content and evidence of mitochondrial dysfunction. With respect to ventricular arrhythmias, abnormalities such as long QT syndrome, frequent premature ventricular contractions, and left ventricular hypertrophy with diastolic dysfunction are commonly observed in obese and diabetic humans. The increased risk of SCD in this population may also be related to excessive cardiac lipid deposition and insulin resistance. While nutritional interventions have had limited success, perhaps due to poor long-term compliance, weight loss and improved cardiorespiratory fitness may reduce the frequency and severity of AF.
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Affiliation(s)
- Edwin A Homan
- Columbia University Medical Center, New York, NY, United States
| | - Michael V Reyes
- Columbia University Medical Center, New York, NY, United States
| | | | - John P Morrow
- Columbia University Medical Center, New York, NY, United States
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34
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Hamilton S, Terentyeva R, Kim TY, Bronk P, Clements RT, O-Uchi J, Csordás G, Choi BR, Terentyev D. Pharmacological Modulation of Mitochondrial Ca 2+ Content Regulates Sarcoplasmic Reticulum Ca 2+ Release via Oxidation of the Ryanodine Receptor by Mitochondria-Derived Reactive Oxygen Species. Front Physiol 2018; 9:1831. [PMID: 30622478 PMCID: PMC6308295 DOI: 10.3389/fphys.2018.01831] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/06/2018] [Indexed: 01/09/2023] Open
Abstract
In a physiological setting, mitochondria increase oxidative phosphorylation during periods of stress to meet increased metabolic demand. This in part is mediated via enhanced mitochondrial Ca2+ uptake, an important regulator of cellular ATP homeostasis. In a pathophysiological setting pharmacological modulation of mitochondrial Ca2+ uptake or retention has been suggested as a therapeutic strategy to improve metabolic homeostasis or attenuate Ca2+-dependent arrhythmias in cardiac disease states. To explore the consequences of mitochondrial Ca2+ accumulation, we tested the effects of kaempferol, an activator of mitochondrial Ca2+ uniporter (MCU), CGP-37157, an inhibitor of mitochondrial Na+/Ca2+ exchanger, and MCU inhibitor Ru360 in rat ventricular myocytes (VMs) from control rats and rats with hypertrophy induced by thoracic aortic banding (TAB). In periodically paced VMs under β-adrenergic stimulation, treatment with kaempferol (10 μmol/L) or CGP-37157 (1 μmol/L) enhanced mitochondrial Ca2+ accumulation monitored by mitochondrial-targeted Ca2+ biosensor mtRCamp1h. Experiments with mitochondrial membrane potential-sensitive dye TMRM revealed this was accompanied by depolarization of the mitochondrial matrix. Using redox-sensitive OMM-HyPer and ERroGFP_iE biosensors, we found treatment with kaempferol or CGP-37157 increased the levels of reactive oxygen species (ROS) in mitochondria and the sarcoplasmic reticulum (SR), respectively. Confocal Ca2+ imaging showed that accelerated Ca2+ accumulation reduced Ca2+ transient amplitude and promoted generation of spontaneous Ca2+ waves in VMs paced under ISO, suggestive of abnormally high activity of the SR Ca2+ release channel ryanodine receptor (RyR). Western blot analyses showed increased RyR oxidation after treatment with kaempferol or CGP-37157 vs. controls. Furthermore, in freshly isolated TAB VMs, confocal Ca2+ imaging demonstrated that enhancement of mitochondrial Ca2+ accumulation further perturbed global Ca2+ handling, increasing the number of cells exhibiting spontaneous Ca2+ waves, shortening RyR refractoriness and decreasing SR Ca2+ content. In ex vivo optically mapped TAB hearts, kaempferol exacerbated proarrhythmic phenotype. On the contrary, incubation of cells with MCU inhibitor Ru360 (2 μmol/L, 30 min) normalized RyR oxidation state, improved intracellular Ca2+ homeostasis and reduced triggered activity in ex vivo TAB hearts. These findings suggest facilitation of mitochondrial Ca2+ uptake in cardiac disease can exacerbate proarrhythmic disturbances in Ca2+ homeostasis via ROS and enhanced activity of oxidized RyRs, while strategies to reduce mitochondrial Ca2+ accumulation can be protective.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
| | - Radmila Terentyeva
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
| | - Tae Yun Kim
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
| | - Peter Bronk
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
| | - Richard T. Clements
- Department of Surgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Providence, RI, United States
| | - Jin O-Uchi
- Lillehei Heart Institute University of Minnesota, Cancer and Cardiovascular Research Building, Minneapolis, MN, United States
| | - György Csordás
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Bum-Rak Choi
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, United States
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35
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Jhun BS, O-Uchi J, Adaniya SM, Cypress MW, Yoon Y. Adrenergic Regulation of Drp1-Driven Mitochondrial Fission in Cardiac Physio-Pathology. Antioxidants (Basel) 2018; 7:antiox7120195. [PMID: 30567380 PMCID: PMC6316402 DOI: 10.3390/antiox7120195] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 12/28/2022] Open
Abstract
Abnormal mitochondrial morphology, especially fragmented mitochondria, and mitochondrial dysfunction are hallmarks of a variety of human diseases including heart failure (HF). Although emerging evidence suggests a link between mitochondrial fragmentation and cardiac dysfunction, it is still not well described which cardiac signaling pathway regulates mitochondrial morphology and function under pathophysiological conditions such as HF. Mitochondria change their shape and location via the activity of mitochondrial fission and fusion proteins. This mechanism is suggested as an important modulator for mitochondrial and cellular functions including bioenergetics, reactive oxygen species (ROS) generation, spatiotemporal dynamics of Ca2+ signaling, cell growth, and death in the mammalian cell- and tissue-specific manners. Recent reports show that a mitochondrial fission protein, dynamin-like/related protein 1 (DLP1/Drp1), is post-translationally modified via cell signaling pathways, which control its subcellular localization, stability, and activity in cardiomyocytes/heart. In this review, we summarize the possible molecular mechanisms for causing post-translational modifications (PTMs) of DLP1/Drp1 in cardiomyocytes, and further discuss how these PTMs of DLP1/Drp1 mediate abnormal mitochondrial morphology and mitochondrial dysfunction under adrenergic signaling activation that contributes to the development and progression of HF.
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Affiliation(s)
- Bong Sook Jhun
- Lillehei Heart Institute, Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Jin O-Uchi
- Lillehei Heart Institute, Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Stephanie M Adaniya
- Lillehei Heart Institute, Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI 02903, USA.
- Department of Medicine, Division of Cardiology, the Alpert Medical School of Brown University, Providence, RI 02903, USA.
| | - Michael W Cypress
- Lillehei Heart Institute, Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Yisang Yoon
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
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36
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Huang X, Song Z, Qu Z. Determinants of early afterdepolarization properties in ventricular myocyte models. PLoS Comput Biol 2018; 14:e1006382. [PMID: 30475801 PMCID: PMC6283611 DOI: 10.1371/journal.pcbi.1006382] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/06/2018] [Accepted: 09/17/2018] [Indexed: 12/20/2022] Open
Abstract
Early afterdepolarizations (EADs) are spontaneous depolarizations during the repolarization phase of an action potential in cardiac myocytes. It is widely known that EADs are promoted by increasing inward currents and/or decreasing outward currents, a condition called reduced repolarization reserve. Recent studies based on bifurcation theories show that EADs are caused by a dual Hopf-homoclinic bifurcation, bringing in further mechanistic insights into the genesis and dynamics of EADs. In this study, we investigated the EAD properties, such as the EAD amplitude, the inter-EAD interval, and the latency of the first EAD, and their major determinants. We first made predictions based on the bifurcation theory and then validated them in physiologically more detailed action potential models. These properties were investigated by varying one parameter at a time or using parameter sets randomly drawn from assigned intervals. The theoretical and simulation results were compared with experimental data from the literature. Our major findings are that the EAD amplitude and takeoff potential exhibit a negative linear correlation; the inter-EAD interval is insensitive to the maximum ionic current conductance but mainly determined by the kinetics of ICa,L and the dual Hopf-homoclinic bifurcation; and both inter-EAD interval and latency vary largely from model to model. Most of the model results generally agree with experimental observations in isolated ventricular myocytes. However, a major discrepancy between modeling results and experimental observations is that the inter-EAD intervals observed in experiments are mainly between 200 and 500 ms, irrespective of species, while those of the mathematical models exhibit a much wider range with some models exhibiting inter-EAD intervals less than 100 ms. Our simulations show that the cause of this discrepancy is likely due to the difference in ICa,L recovery properties in different mathematical models, which needs to be addressed in future action potential model development. Early afterdepolarizations (EADs) are abnormal depolarizations during the plateau phase of action potential in cardiac myocytes, arising from a dual Hopf-homoclinic bifurcation. The same bifurcations are also responsible for certain types of bursting behaviors in other cell types, such as beta cells and neuronal cells. EADs are known to play important role in the genesis of lethal arrhythmias and have been widely studied in both experiments and computer models. However, a detailed comparison between the properties of EADs observed in experiments and those from mathematical models have not been carried out. In this study, we performed theoretical analyses and computer simulations of different ventricular action potential models as well as different species to investigate the properties of EADs and compared these properties to those observed in experiments. While the EAD properties in the action potential models capture many of the EAD properties seen in experiments, the inter-EAD intervals in the computer models differ a lot from model to model, and some of them show very large discrepancy with those observed in experiments. This discrepancy needs to be addressed in future cardiac action potential model development.
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Affiliation(s)
- Xiaodong Huang
- Department of Physics, South China University of Technology, Guangzhou, China
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail:
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