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Williams ZJ, Payne LB, Wu X, Gourdie RG. New focus on cardiac voltage-gated sodium channel β1 and β1B: Novel targets for treating and understanding arrhythmias? Heart Rhythm 2024:S1547-5271(24)02742-5. [PMID: 38908461 DOI: 10.1016/j.hrthm.2024.06.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/09/2024] [Accepted: 06/17/2024] [Indexed: 06/24/2024]
Abstract
Voltage-gated sodium channels (VGSCs) are transmembrane protein complexes that are vital to the generation and propagation of action potentials in nerve and muscle fibers. The canonical VGSC is generally conceived as a heterotrimeric complex formed by 2 classes of membrane-spanning subunit: an α-subunit (pore forming) and 2 β-subunits (non-pore forming). NaV1.5 is the main sodium channel α-subunit of mammalian ventricle, with lower amounts of other α-subunits, including NaV1.6, being present. There are 4 β-subunits (β1-β4) encoded by 4 genes (SCN1B-SCN4B), each of which is expressed in cardiac tissues. Recent studies suggest that in addition to assignments in channel gating and trafficking, products of Scn1b may have novel roles in conduction of action potential in the heart and intracellular signaling. This includes evidence that the β-subunit extracellular amino-terminal domain facilitates adhesive interactions in intercalated discs and that its carboxyl-terminal region is a substrate for a regulated intramembrane proteolysis (RIP) signaling pathway, with a carboxyl-terminal peptide generated by β1 RIP trafficked to the nucleus and altering transcription of various genes, including NaV1.5. In addition to β1, the Scn1b gene encodes for an alternative splice variant, β1B, which contains an identical extracellular adhesion domain to β1 but has a unique carboxyl-terminus. Although β1B is generally understood to be a secreted variant, evidence indicates that when co-expressed with NaV1.5, it is maintained at the cell membrane, suggesting potential unique roles for this understudied protein. In this review, we focus on what is known of the 2 β-subunit variants encoded by Scn1b in heart, with particular focus on recent findings and the questions raised by this new information. We also explore data that indicate β1 and β1B may be attractive targets for novel antiarrhythmic therapeutics.
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Affiliation(s)
- Zachary J Williams
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Laura Beth Payne
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Xiaobo Wu
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Robert G Gourdie
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia; School of Medicine, Virgina Polytechnic University, Roanoke, Virginia; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic University, Blacksburg, Virginia.
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2
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Catrina BI, Batar F, Manitiu I, Prodan L, Tanasescu C, Filip T. Concepts of Cardiac Dyssynchrony and Dynamic Approach. Diagnostics (Basel) 2024; 14:937. [PMID: 38732350 PMCID: PMC11083078 DOI: 10.3390/diagnostics14090937] [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: 02/21/2024] [Revised: 04/12/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024] Open
Abstract
Cardiac conduction involves electrical activity from one myocyte to another, creating coordinated contractions in each. Disruptions in the conducting system, such as left bundle branch block (LBBB), can result in premature activation of specific regions of the heart, leading to heart failure and increased morbidity and mortality. Structural alterations in T-tubules and the sarcoplasmic reticulum can lead to dyssynchrony, a condition that can be treated by cardiac resynchronization therapy (CRT), which stands as a cornerstone in this pathology. The heterogeneity in patient responses underscored the necessity of improving the diagnostic approach. Vectocardiography, ultra-high-frequency ECG, 3D echocardiography, and electrocardiographic imaging seem to offer advanced precision in identifying optimal candidates for CRT in addition to the classic diagnostic methods. The advent of His bundle pacing and left bundle branch pacing further refined the approach in the treatment of dyssynchrony, offering more physiological pacing modalities that promise enhanced outcomes by maintaining or restoring the natural sequence of ventricular activation. HOT-CRT emerges as a pivotal innovation combining the benefits of CRT with the precision of His bundle or left bundle branch area pacing to optimize cardiac function in a subset of patients where traditional CRT might fall short.
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Affiliation(s)
- Bianca Iulia Catrina
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
- Pathophysiology Department, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania
| | - Florina Batar
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
- Physiology Pathophysiology Department, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania
| | - Ioan Manitiu
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
- Cardiology Department, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania
| | - Liliana Prodan
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
- Pathophysiology Department, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania
| | - Ciprian Tanasescu
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
- Clinical Surgical Department, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania
| | - Teodora Filip
- County Clinical Emergency Hospital of Sibiu, 550245 Sibiu, Romania; (F.B.); (I.M.); (C.T.); (T.F.)
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Li E, van der Heyden MAG. The network of cardiac K IR2.1: its function, cellular regulation, electrical signaling, diseases and new drug avenues. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03116-5. [PMID: 38683369 DOI: 10.1007/s00210-024-03116-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
The functioning of the human heart relies on complex electrical and communication systems that coordinate cardiac contractions and sustain rhythmicity. One of the key players contributing to this intricate system is the KIR2.1 potassium ion channel, which is encoded by the KCNJ2 gene. KIR2.1 channels exhibit abundant expression in both ventricular myocytes and Purkinje fibers, exerting an important role in maintaining the balance of intracellular potassium ion levels within the heart. And by stabilizing the resting membrane potential and contributing to action potential repolarization, these channels have an important role in cardiac excitability also. Either gain- or loss-of-function mutations, but also acquired impairments of their function, are implicated in the pathogenesis of diverse types of cardiac arrhythmias. In this review, we aim to elucidate the system functions of KIR2.1 channels related to cellular electrical signaling, communication, and their contributions to cardiovascular disease. Based on this knowledge, we will discuss existing and new pharmacological avenues to modulate their function.
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Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands.
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Struckman HL, Moise N, King DR, Soltisz A, Buxton A, Dunlap I, Chen Z, Radwański PB, Weinberg SH, Veeraraghavan R. Unraveling Impacts of Chamber-Specific Differences in Intercalated Disc Ultrastructure and Molecular Organization on Cardiac Conduction. JACC Clin Electrophysiol 2023; 9:2425-2443. [PMID: 37498248 PMCID: PMC11102000 DOI: 10.1016/j.jacep.2023.05.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 07/28/2023]
Abstract
BACKGROUND Propagation of action potentials through the heart coordinates the heartbeat. Thus, intercalated discs, specialized cell-cell contact sites that provide electrical and mechanical coupling between cardiomyocytes, are an important target for study. Impaired propagation leads to arrhythmias in many pathologies, where intercalated disc remodeling is a common finding, hence the importance and urgency of understanding propagation dependence on intercalated disc structure. Conventional modeling approaches cannot predict changes in propagation elicited by perturbations that alter intercalated disc ultrastructure or molecular organization, because of lack of quantitative structural data at subcellular through nano scales. OBJECTIVES This study sought to quantify intercalated disc structure at these spatial scales in the healthy adult mouse heart and relate them to chamber-specific properties of propagation as a precursor to understanding the effects of pathological intercalated disc remodeling. METHODS Using super-resolution light microscopy, electron microscopy, and computational image analysis, we provide here the first ever systematic, multiscale quantification of intercalated disc ultrastructure and molecular organization. RESULTS By incorporating these data into a rule-based model of cardiac tissue with realistic intercalated disc structure, and comparing model predictions of electrical propagation with experimental measures of conduction velocity, we reveal that atrial intercalated discs can support faster conduction than their ventricular counterparts, which is normally masked by interchamber differences in myocyte geometry. Further, we identify key ultrastructural and molecular organization features underpinning the ability of atrial intercalated discs to support faster conduction. CONCLUSIONS These data provide the first stepping stone to elucidating chamber-specific effects of pathological intercalated disc remodeling, as occurs in many arrhythmic diseases.
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Affiliation(s)
- Heather L Struckman
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Nicolae Moise
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - D Ryan King
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Andrew Soltisz
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Andrew Buxton
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Izabella Dunlap
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Zhenhui Chen
- Krannert Cardiovascular Research Center, Department of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Przemysław B Radwański
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Seth H Weinberg
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
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5
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Frangogiannis NG. Fibroblasts, myofibroblasts and cardiac arrhythmias. THE JOURNAL OF CARDIOVASCULAR AGING 2023; 3:43. [PMID: 38235057 PMCID: PMC10793996 DOI: 10.20517/jca.2023.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Affiliation(s)
- Nikolaos G Frangogiannis
- The Wilf Family Cardiovascular Research Institute, Department of Medicine and Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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6
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Adams WP, Raisch TB, Zhao Y, Davalos R, Barrett S, King DR, Bain CB, Colucci-Chang K, Blair GA, Hanlon A, Lozano A, Veeraraghavan R, Wan X, Deschenes I, Smyth JW, Hoeker GS, Gourdie RG, Poelzing S. Extracellular Perinexal Separation Is a Principal Determinant of Cardiac Conduction. Circ Res 2023; 133:658-673. [PMID: 37681314 PMCID: PMC10561697 DOI: 10.1161/circresaha.123.322567] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Abstract
BACKGROUND Cardiac conduction is understood to occur through gap junctions. Recent evidence supports ephaptic coupling as another mechanism of electrical communication in the heart. Conduction via gap junctions predicts a direct relationship between conduction velocity (CV) and bulk extracellular resistance. By contrast, ephaptic theory is premised on the existence of a biphasic relationship between CV and the volume of specialized extracellular clefts within intercalated discs such as the perinexus. Our objective was to determine the relationship between ventricular CV and structural changes to micro- and nanoscale extracellular spaces. METHODS Conduction and Cx43 (connexin43) protein expression were quantified from optically mapped guinea pig whole-heart preparations perfused with the osmotic agents albumin, mannitol, dextran 70 kDa, or dextran 2 MDa. Peak sodium current was quantified in isolated guinea pig ventricular myocytes. Extracellular resistance was quantified by impedance spectroscopy. Intercellular communication was assessed in a heterologous expression system with fluorescence recovery after photobleaching. Perinexal width was quantified from transmission electron micrographs. RESULTS CV primarily in the transverse direction of propagation was significantly reduced by mannitol and increased by albumin and both dextrans. The combination of albumin and dextran 70 kDa decreased CV relative to albumin alone. Extracellular resistance was reduced by mannitol, unchanged by albumin, and increased by both dextrans. Cx43 expression and conductance and peak sodium currents were not significantly altered by the osmotic agents. In response to osmotic agents, perinexal width, in order of narrowest to widest, was albumin with dextran 70 kDa; albumin or dextran 2 MDa; dextran 70 kDa or no osmotic agent, and mannitol. When compared in the same order, CV was biphasically related to perinexal width. CONCLUSIONS Cardiac conduction does not correlate with extracellular resistance but is biphasically related to perinexal separation, providing evidence that the relationship between CV and extracellular volume is determined by ephaptic mechanisms under conditions of normal gap junctional coupling.
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Affiliation(s)
- William P. Adams
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Tristan B. Raisch
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Yajun Zhao
- School of Biomedical Engineering and Sciences, Virginia Tech
| | - Rafael Davalos
- School of Biomedical Engineering and Sciences, Virginia Tech
| | | | - D. Ryan King
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Chandra B. Bain
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
| | - Katrina Colucci-Chang
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- School of Biomedical Engineering and Sciences, Virginia Tech
| | - Grace A. Blair
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
| | - Alexandra Hanlon
- Virginia Tech Center for Biostatistics and Health Data Science, Roanoke, Virginia
| | - Alicia Lozano
- Virginia Tech Center for Biostatistics and Health Data Science, Roanoke, Virginia
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, College of Engineering, The Ohio State University
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - Xiaoping Wan
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - Isabelle Deschenes
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center
| | - James W. Smyth
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Department of Biological Sciences, College of Science, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
| | - Gregory S. Hoeker
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
| | - Robert G. Gourdie
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- School of Biomedical Engineering and Sciences, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
| | - Steven Poelzing
- Center for Vascular and Heart Research at Fralin Biomedical Research Institute at VTC
- Translational Biology, Medicine and Health Program at Virginia Tech
- School of Biomedical Engineering and Sciences, Virginia Tech
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia
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Wang Y, Li Q, Tao B, Angelini M, Ramadoss S, Sun B, Wang P, Krokhaleva Y, Ma F, Gu Y, Espinoza A, Yamauchi K, Pellegrini M, Novitch B, Olcese R, Qu Z, Song Z, Deb A. Fibroblasts in heart scar tissue directly regulate cardiac excitability and arrhythmogenesis. Science 2023; 381:1480-1487. [PMID: 37769108 PMCID: PMC10768850 DOI: 10.1126/science.adh9925] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/11/2023] [Indexed: 09/30/2023]
Abstract
After heart injury, dead heart muscle is replaced by scar tissue. Fibroblasts can electrically couple with myocytes, and changes in fibroblast membrane potential can lead to myocyte excitability, which suggests that fibroblast-myocyte coupling in scar tissue may be responsible for arrhythmogenesis. However, the physiologic relevance of electrical coupling of myocytes and fibroblasts and its impact on cardiac excitability in vivo have never been demonstrated. We genetically engineered a mouse that expresses the optogenetic cationic channel ChR2 (H134R) exclusively in cardiac fibroblasts. After myocardial infarction, optical stimulation of scar tissue elicited organ-wide cardiac excitation and induced arrhythmias in these animals. Complementing computational modeling with experimental approaches, we showed that gap junctional and ephaptic coupling, in a synergistic yet functionally redundant manner, excited myocytes coupled to fibroblasts.
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Affiliation(s)
- Yijie Wang
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Qihao Li
- Peng Cheng Laboratory, Shenzhen, Guangdong 518000, China
| | - Bo Tao
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Marina Angelini
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sivakumar Ramadoss
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Baiming Sun
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ping Wang
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yuliya Krokhaleva
- UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Feiyang Ma
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yiqian Gu
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Alejandro Espinoza
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ken Yamauchi
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Bennett Novitch
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Riccardo Olcese
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Zhilin Qu
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Zhen Song
- Peng Cheng Laboratory, Shenzhen, Guangdong 518000, China
| | - Arjun Deb
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
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8
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Haq KT, Roberts A, Berk F, Allen S, Swift LM, Posnack NG. KairoSight-3.0: A validated optical mapping software to characterize cardiac electrophysiology, excitation-contraction coupling, and alternans. JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY PLUS 2023; 5:100043. [PMID: 37786807 PMCID: PMC10544851 DOI: 10.1016/j.jmccpl.2023.100043] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Background Cardiac optical mapping is an imaging technique that measures fluorescent signals across a cardiac preparation. Dual optical imaging of voltage-sensitive and calcium-sensitive probes allows for simultaneous recordings of cardiac action potentials and intracellular calcium transients with high spatiotemporal resolution. The analysis of these complex optical datasets is both time intensive and technically challenging; as such, we have developed a software package for semi-automated image processing and analysis. Herein, we report an updated version of our software package (KairoSight-3.0) with features to enhance the characterization of cardiac parameters using optical signals. Methods To test software validity and applicability, we used Langendorff-perfused heart preparations to record transmembrane voltage and intracellular calcium signals from the epicardial surface. Isolated hearts from guinea pigs and rats were loaded with a potentiometric dye (RH237) and/or calcium indicator dye (Rhod-2AM) and fluorescent signals were acquired. We used Python 3.8.5 programming language to develop the KairoSight-3.0 software. Cardiac maps were validated with a user-specified manual mapping approach. Results Manual maps of action potential duration (30 or 80 % repolarization), calcium transient duration (30 or 80 % reuptake), action potential and calcium transient alternans were constituted to validate the accuracy of software-generated maps. Manual and software maps had high accuracy, with >97 % of manual and software values falling within 10 ms of each other and >75 % within 5 ms for action potential duration and calcium transient duration measurements (n = 1000-2000 pixels). Further, our software package includes additional measurement tools to analyze signal-to-noise ratio, conduction velocity, action potential and calcium transient alternans, and action potential-calcium transient coupling time to produce physiologically meaningful optical maps. Conclusions KairoSight-3.0 has enhanced capabilities to perform measurements of cardiac electrophysiology, calcium handling, alternans, and the excitation-contraction coupling with satisfactory accuracy.
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Affiliation(s)
- Kazi T. Haq
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Anysja Roberts
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Fiona Berk
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Department of Biomedical Engineering, School of Engineering and Applied Sciences: George Washington University, Washington, DC 20037, USA
| | - Samuel Allen
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
| | - Luther M. Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, DC 20010, USA
- Children’s National Heart Institute, Children’s National Hospital, Washington, DC 20010, USA
- Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences: George Washington University, Washington, DC 20037, USA
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9
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Nielsen MS, van Opbergen CJM, van Veen TAB, Delmar M. The intercalated disc: a unique organelle for electromechanical synchrony in cardiomyocytes. Physiol Rev 2023; 103:2271-2319. [PMID: 36731030 PMCID: PMC10191137 DOI: 10.1152/physrev.00021.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 01/24/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
The intercalated disc (ID) is a highly specialized structure that connects cardiomyocytes via mechanical and electrical junctions. Although described in some detail by light microscopy in the 19th century, it was in 1966 that electron microscopy images showed that the ID represented apposing cell borders and provided detailed insight into the complex ID nanostructure. Since then, much has been learned about the ID and its molecular composition, and it has become evident that a large number of proteins, not all of them involved in direct cell-to-cell coupling via mechanical or gap junctions, reside at the ID. Furthermore, an increasing number of functional interactions between ID components are emerging, leading to the concept that the ID is not the sum of isolated molecular silos but an interacting molecular complex, an "organelle" where components work in concert to bring about electrical and mechanical synchrony. The aim of the present review is to give a short historical account of the ID's discovery and an updated overview of its composition and organization, followed by a discussion of the physiological implications of the ID architecture and the local intermolecular interactions. The latter will focus on both the importance of normal conduction of cardiac action potentials as well as the impact on the pathophysiology of arrhythmias.
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Affiliation(s)
- Morten S Nielsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chantal J M van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
| | - Toon A B van Veen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, New York, United States
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10
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Strocchi M, Longobardi S, Augustin CM, Gsell MAF, Petras A, Rinaldi CA, Vigmond EJ, Plank G, Oates CJ, Wilkinson RD, Niederer SA. Cell to whole organ global sensitivity analysis on a four-chamber heart electromechanics model using Gaussian processes emulators. PLoS Comput Biol 2023; 19:e1011257. [PMID: 37363928 DOI: 10.1371/journal.pcbi.1011257] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 06/09/2023] [Indexed: 06/28/2023] Open
Abstract
Cardiac pump function arises from a series of highly orchestrated events across multiple scales. Computational electromechanics can encode these events in physics-constrained models. However, the large number of parameters in these models has made the systematic study of the link between cellular, tissue, and organ scale parameters to whole heart physiology challenging. A patient-specific anatomical heart model, or digital twin, was created. Cellular ionic dynamics and contraction were simulated with the Courtemanche-Land and the ToR-ORd-Land models for the atria and the ventricles, respectively. Whole heart contraction was coupled with the circulatory system, simulated with CircAdapt, while accounting for the effect of the pericardium on cardiac motion. The four-chamber electromechanics framework resulted in 117 parameters of interest. The model was broken into five hierarchical sub-models: tissue electrophysiology, ToR-ORd-Land model, Courtemanche-Land model, passive mechanics and CircAdapt. For each sub-model, we trained Gaussian processes emulators (GPEs) that were then used to perform a global sensitivity analysis (GSA) to retain parameters explaining 90% of the total sensitivity for subsequent analysis. We identified 45 out of 117 parameters that were important for whole heart function. We performed a GSA over these 45 parameters and identified the systemic and pulmonary peripheral resistance as being critical parameters for a wide range of volumetric and hemodynamic cardiac indexes across all four chambers. We have shown that GPEs provide a robust method for mapping between cellular properties and clinical measurements. This could be applied to identify parameters that can be calibrated in patient-specific models or digital twins, and to link cellular function to clinical indexes.
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Affiliation(s)
- Marina Strocchi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Stefano Longobardi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | | | | | - Argyrios Petras
- Johann Radon Institute for Computational and Applied Mathematics (RICAM), Linz, Austria
| | - Christopher A Rinaldi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Edward J Vigmond
- University of Bordeaux, CNRS, Bordeaux, Talence, France
- IHU Liryc, Bordeaux, Talence, France
| | - Gernot Plank
- Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Chris J Oates
- Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Steven A Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Alan Turing Institute, London, United Kingdom
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11
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Struckman HL, Moise N, King DR, Soltisz A, Buxton A, Dunlap I, Chen Z, Radwański PB, Weinberg SH, Veeraraghavan R. Unraveling Chamber-specific Differences in Intercalated Disc Ultrastructure and Molecular Organization and Their Impact on Cardiac Conduction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.13.528369. [PMID: 36824727 PMCID: PMC9949041 DOI: 10.1101/2023.02.13.528369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
During each heartbeat, the propagation of action potentials through the heart coordinates the contraction of billions of individual cardiomyocytes and is thus, a critical life process. Unsurprisingly, intercalated discs, which are cell-cell contact sites specialized to provide electrical and mechanical coupling between adjacent cardiomyocytes, have been the focus of much investigation. Slowed or disrupted propagation leads to potentially life-threatening arrhythmias in a wide range of pathologies, where intercalated disc remodeling is a common finding. Hence, the importance and urgency of understanding intercalated disc structure and its influence on action potential propagation. Surprisingly, however, conventional modeling approaches cannot predict changes in propagation elicited by perturbations that alter intercalated disc ultrastructure or molecular organization, owing to lack of quantitative structural data at subcellular through nano scales. In order to address this critical gap in knowledge, we sought to quantify intercalated disc structure at these finer spatial scales in the healthy adult mouse heart and relate them to function in a chamber-specific manner as a precursor to understanding the impacts of pathological intercalated disc remodeling. Using super-resolution light microscopy, electron microscopy, and computational image analysis, we provide here the first ever systematic, multiscale quantification of intercalated disc ultrastructure and molecular organization. By incorporating these data into a rule-based model of cardiac tissue with realistic intercalated disc structure, and comparing model predictions of electrical propagation with experimental measures of conduction velocity, we reveal that atrial intercalated discs can support faster conduction than their ventricular counterparts, which is normally masked by inter-chamber differences in myocyte geometry. Further, we identify key ultrastructural and molecular organization features underpinning the ability of atrial intercalated discs to support faster conduction. These data provide the first stepping stone to elucidating chamber-specific impacts of pathological intercalated disc remodeling, as occurs in many arrhythmic diseases.
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12
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Leybaert L, De Smet MA, Lissoni A, Allewaert R, Roderick HL, Bultynck G, Delmar M, Sipido KR, Witschas K. Connexin hemichannels as candidate targets for cardioprotective and anti-arrhythmic treatments. J Clin Invest 2023; 133:168117. [PMID: 36919695 PMCID: PMC10014111 DOI: 10.1172/jci168117] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023] Open
Abstract
Connexins are crucial cardiac proteins that form hemichannels and gap junctions. Gap junctions are responsible for the propagation of electrical and chemical signals between myocardial cells and cells of the specialized conduction system in order to synchronize the cardiac cycle and steer cardiac pump function. Gap junctions are normally open, while hemichannels are closed, but pathological circumstances may close gap junctions and open hemichannels, thereby perturbing cardiac function and homeostasis. Current evidence demonstrates an emerging role of hemichannels in myocardial ischemia and arrhythmia, and tools are now available to selectively inhibit hemichannels without inhibiting gap junctions as well as to stimulate hemichannel incorporation into gap junctions. We review available experimental evidence for hemichannel contributions to cellular pro-arrhythmic events in ventricular and atrial cardiomyocytes, and link these to insights at the level of molecular control of connexin-43-based hemichannel opening. We conclude that a double-edged approach of both preventing hemichannel opening and preserving gap junctional function will be key for further research and development of new connexin-based experimental approaches for treating heart disease.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Maarten Aj De Smet
- Physiology Group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Alessio Lissoni
- Physiology Group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Rosalie Allewaert
- Physiology Group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, and
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Mario Delmar
- Leon H. Charney Division of Cardiology, School of Medicine, New York University, New York, USA
| | - Karin R Sipido
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, and
| | - Katja Witschas
- Physiology Group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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13
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Nano-scale solution of the Poisson-Nernst-Planck (PNP) equations in a fraction of two neighboring cells reveals the magnitude of intercellular electrochemical waves. PLoS Comput Biol 2023; 19:e1010895. [PMID: 36791152 PMCID: PMC9974139 DOI: 10.1371/journal.pcbi.1010895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 02/28/2023] [Accepted: 01/23/2023] [Indexed: 02/16/2023] Open
Abstract
The basic building blocks of the electrophysiology of cardiomyocytes are ion channels integrated in the cell membranes. Close to the ion channels there are very strong electrical and chemical gradients. However, these gradients extend for only a few nano-meters and are therefore commonly ignored in mathematical models. The full complexity of the dynamics is modelled by the Poisson-Nernst-Planck (PNP) equations but these equations must be solved using temporal and spatial scales of nano-seconds and nano-meters. Here we report solutions of the PNP equations in a fraction of two abuttal cells separated by a tiny extracellular space. We show that when only the potassium channels of the two cells are open, a stationary solution is reached with the well-known Debye layer close to the membranes. When the sodium channels of one of the cells are opened, a very strong and brief electrochemical wave emanates from the channels. If the extracellular space is sufficiently small and the number of sodium channels is sufficiently high, the wave extends all the way over to the neighboring cell and may therefore explain cardiac conduction even at very low levels of gap junctional coupling.
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14
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Wang S, Jia T, Liu G, Lu X, Yang Q, Zhu C. Mapping the research trends and hot topics of ventricular arrhythmia: A bibliometric analysis from 2001 to 2020. Front Cardiovasc Med 2022; 9:856695. [PMID: 36337873 PMCID: PMC9631785 DOI: 10.3389/fcvm.2022.856695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 10/03/2022] [Indexed: 08/30/2023] Open
Abstract
BACKGROUND Studies of ventricular arrhythmia (VA) have drawn much scholarly attention over the past two decades. Our study aimed to assess the current situation and detect the changing research trends of VA quantitatively and qualitatively. MATERIALS AND METHODS All the information used in our statistical and bibliometric analysis were collected and summarized from papers retrieved from the Web of Science Core Collection (WoSCC) database on December 22, 2021 using certain criteria. Visual analytics were realized using CiteSpace, VOSviewer, the bibliometrix R package, and the bibliometric online analysis platform. RESULTS A total of 6,897 papers (6,711 original articles, 182 proceedings papers, three book chapters, and one data paper) were published in 796 journals that concentrated on the research areas of cardiovascular and critical care medicine. The most productive country and influential institution was the USA and the Mayo Clinic, respectively. Heart Rhythm (551 articles and 8,342 local citations) published the most manuscripts. The keyword co-occurrence and co-citation network of references analyses revealed that the most popular terms were ventricular tachycardia, ventricular fibrillation, catheter ablation, implantable cardioverter defibrillator (ICD), and sudden cardiac death (SCD). Further, the burst detection analysis demonstrated that topics strongly associated with clinical prognosis, such as meta-analysis, long-term outcomes, and impact, were new concerns. CONCLUSION Our study offers a comprehensive picture of VA research and provides profound insights into the current research status. Moreover, we show that new topics within the VA research field have focused more on prognosis and evidence-based clinical guidelines.
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Affiliation(s)
| | | | | | | | | | - Changqing Zhu
- Department of Emergency Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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15
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Histologic, viral, and molecular correlates of heart disease in fatal COVID-19. Ann Diagn Pathol 2022; 60:151983. [PMID: 35660807 PMCID: PMC9148434 DOI: 10.1016/j.anndiagpath.2022.151983] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 12/13/2022]
Abstract
Cardiac manifestations are common in severe COVID-19. This study compared the histologic, viral, and molecular findings in cardiac tissue in fatal COVID-19 (n = 11) and controls (n = 11). In situ hybridization (SARS-CoV2 RNA) and immunohistochemistry for viral proteins and the host response were quantified for the samples and compared with qRTPCR and Western blot data. Control hearts showed a high resident population of macrophages that had variable ACE2 expression. Cardiac ACE2 expression was 10× greater in the heart tissues of cases and controls with obesity or type II diabetes. Multifocal endothelial cell swelling and degeneration, perivascular edema plus microvascular thrombi were unique to the cases. SARS-CoV2 RNA and nucleocapsid protein were rarely detected in situ in any COVID-19 heart. However, in each case abundant SARS-CoV-2 spike protein was evident. Co-expression experiments showed that the spike protein localized mostly to the ACE2+ interstitial macrophages/pericytes that were activated as evidenced by increased IL6 and TNFα expression. Western blots confirmed the presence of the viral spike protein, but not the nucleocapsid protein, in the cardiac homogenates. The intercalated disc proteins connexin 43, the primary cardiac gap junction protein, and NaV1.5, the predominant cardiac sodium channel, each showed marked lateral migration in the myocytes in the cases, which would increase the risk of reentrant arrhythmias. It is concluded that the viral spike protein, endocytosed by macrophages/pericytes, can induce a myocarditis with the possibility of conduction dysfunction due to abnormal localization of key intercalated disc proteins.
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16
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Rey S, Ohm H, Klämbt C. Axonal ion homeostasis and glial differentiation. FEBS J 2022. [PMID: 35943294 DOI: 10.1111/febs.16594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/26/2022] [Accepted: 08/08/2022] [Indexed: 11/27/2022]
Abstract
The brain is the ultimate control unit of the body. It conducts accurate, fast and reproducible calculations to control motor actions affecting mating, foraging and flight or fight decisions. Therefore, during evolution, better and more efficient brains have emerged. However, even simple brains are complex organs. They are formed by glial cells and neurons that establish highly intricate networks to enable information collection, processing and eventually, a precise motor control. Here, we review and connect some well-established and some hidden pieces of information to set the focus on ion homeostasis as a driving force in glial differentiation promoting signalling speed and accuracy.
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Affiliation(s)
- Simone Rey
- Institut für Neuro‐ und Verhaltensbiologie Münster Germany
| | - Henrike Ohm
- Institut für Neuro‐ und Verhaltensbiologie Münster Germany
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17
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Zhu C, Rajendran PS, Hanna P, Efimov IR, Salama G, Fowlkes CC, Shivkumar K. High-resolution structure-function mapping of intact hearts reveals altered sympathetic control of infarct border zones. JCI Insight 2022; 7:153913. [PMID: 35132963 PMCID: PMC8855798 DOI: 10.1172/jci.insight.153913] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Remodeling of injured sympathetic nerves on the heart after myocardial infarction (MI) contributes to adverse outcomes such as sudden arrhythmic death, yet the underlying structural mechanisms are poorly understood. We sought to examine microstructural changes on the heart after MI and to directly link these changes with electrical dysfunction. We developed a high-resolution pipeline for anatomically precise alignment of electrical maps with structural myofiber and nerve-fiber maps created by customized computer vision algorithms. Using this integrative approach in a mouse model, we identified distinct structure-function correlates to objectively delineate the infarct border zone, a known source of arrhythmias after MI. During tyramine-induced sympathetic nerve activation, we demonstrated regional patterns of altered electrical conduction aligned directly with altered neuroeffector junction distribution, pointing to potential neural substrates for cardiac arrhythmia. This study establishes a synergistic framework for examining structure-function relationships after MI with microscopic precision that has potential to advance understanding of arrhythmogenic mechanisms.
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Affiliation(s)
- Ching Zhu
- Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Pradeep S Rajendran
- Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Peter Hanna
- Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Guy Salama
- Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Charless C Fowlkes
- Department of Computer Science, University of California, Irvine, Irvine, California, USA
| | - Kalyanam Shivkumar
- Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
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18
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Jæger KH, Tveito A. Deriving the Bidomain Model of Cardiac Electrophysiology From a Cell-Based Model; Properties and Comparisons. Front Physiol 2022; 12:811029. [PMID: 35069265 PMCID: PMC8782150 DOI: 10.3389/fphys.2021.811029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/13/2021] [Indexed: 11/23/2022] Open
Abstract
The bidomain model is considered to be the gold standard for numerical simulation of the electrophysiology of cardiac tissue. The model provides important insights into the conduction properties of the electrochemical wave traversing the cardiac muscle in every heartbeat. However, in normal resolution, the model represents the average over a large number of cardiomyocytes, and more accurate models based on representations of all individual cells have therefore been introduced in order to gain insight into the conduction properties close to the myocytes. The more accurate model considered here is referred to as the EMI model since both the extracellular space (E), the cell membrane (M) and the intracellular space (I) are explicitly represented in the model. Here, we show that the bidomain model can be derived from the cell-based EMI model and we thus reveal the close relation between the two models, and obtain an indication of the error introduced in the approximation. Also, we present numerical simulations comparing the results of the two models and thereby highlight both similarities and differences between the models. We observe that the deviations between the solutions of the models become larger for larger cell sizes. Furthermore, we observe that the bidomain model provides solutions that are very similar to the EMI model when conductive properties of the tissue are in the normal range, but large deviations are present when the resistance between cardiomyocytes is increased.
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Affiliation(s)
| | - Aslak Tveito
- Simula Research Laboratory, Oslo, Norway.,Department of Informatics, University of Oslo, Oslo, Norway
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19
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Song S, Kim KY, Lee SH, Kim KK, Lee K, Lee W, Jeon H, Ko SH. Recent Advances in 1D Nanomaterial‐Based Bioelectronics for Healthcare Applications. ADVANCED NANOBIOMED RESEARCH 2021. [DOI: 10.1002/anbr.202100111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Sangmin Song
- Applied Nano and Thermal Science Lab Department of Mechanical Engineering Seoul National University 1 Gwanak-ro Gwanak-gu Seoul 151-742 Korea
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
| | - Kyung Yeun Kim
- Applied Nano and Thermal Science Lab Department of Mechanical Engineering Seoul National University 1 Gwanak-ro Gwanak-gu Seoul 151-742 Korea
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
| | - Sun Hee Lee
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
| | - Kyun Kyu Kim
- Department of Chemical Engineering Stanford University Stanford CA 94305 USA
| | - Kyungwoo Lee
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
| | - Wonryung Lee
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
| | - Hojeong Jeon
- Center for Biomaterials Biomedical Research Institute Korea Institute of Science and Technology (KIST) 5, Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Korea
- KU-KIST Graduate School of Converging Science and Technology Korea University 145, Anam-ro Seongbuk-gu Seoul 02841 Korea
| | - Seung Hwan Ko
- Applied Nano and Thermal Science Lab Department of Mechanical Engineering Seoul National University 1 Gwanak-ro Gwanak-gu Seoul 151-742 Korea
- Institute of Advanced Machines and Design/Institute of Engineering Research Seoul National University Seoul 08826 Korea
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20
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Poelzing S, Weinberg SH, Keener JP. Initiation and entrainment of multicellular automaticity via diffusion limited extracellular domains. Biophys J 2021; 120:5279-5294. [PMID: 34757078 DOI: 10.1016/j.bpj.2021.10.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 09/12/2021] [Accepted: 10/26/2021] [Indexed: 01/07/2023] Open
Abstract
Electrically excitable cells often spontaneously and synchronously depolarize in vitro and in vivo preparations. It remains unclear how cells entrain and autorhythmically activate above the intrinsic mean activation frequency of isolated cells with or without pacemaking mechanisms. Recent studies suggest that cyclic ion accumulation and depletion in diffusion-limited extracellular volumes modulate electrophysiology by ephaptic mechanisms (nongap junction or synaptic coupling). This report explores how potassium accumulation and depletion in a restricted extracellular domain induces spontaneous action potentials in two different computational models of excitable cells without gap junctional coupling: Hodgkin-Huxley and Luo-Rudy. Importantly, neither model will spontaneously activate on its own without external stimuli. Simulations demonstrate that cells sharing a diffusion-limited extracellular compartment can become autorhythmic and entrained despite intercellular electrical heterogeneity. Autorhythmic frequency is modulated by the cleft volume and potassium fluxes through the cleft. Additionally, inexcitable cells can suppress or induce autorhythmic activity in an excitable cell via a shared cleft. Diffusion-limited shared clefts can also entrain repolarization. Critically, this model predicts a mechanism by which diffusion-limited shared clefts can initiate, entrain, and modulate multicellular automaticity in the absence of gap junctions.
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Affiliation(s)
- Steven Poelzing
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Heart and Reparative Medicine, and the Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Roanoke, Virginia.
| | - Seth H Weinberg
- Department of Biomedical Engineering, Davis Heart and Lung Research Institute, and the Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - James P Keener
- Department of Mathematics, University of Utah, Salt Lake City, Utah
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21
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Nowak MB, Veeraraghavan R, Poelzing S, Weinberg SH. Cellular Size, Gap Junctions, and Sodium Channel Properties Govern Developmental Changes in Cardiac Conduction. Front Physiol 2021; 12:731025. [PMID: 34759834 PMCID: PMC8573326 DOI: 10.3389/fphys.2021.731025] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/28/2021] [Indexed: 11/26/2022] Open
Abstract
Electrical conduction in cardiac ventricular tissue is regulated via sodium (Na+) channels and gap junctions (GJs). We and others have recently shown that Na+channels preferentially localize at the site of cell-cell junctions, the intercalated disc (ID), in adult cardiac tissue, facilitating coupling via the formation of intercellular Na+nanodomains, also termed ephaptic coupling (EpC). Several properties governing EpC vary with age, including Na+channel and GJ expression and distribution and cell size. Prior work has shown that neonatal cardiomyocytes have immature IDs with Na+channels and GJs diffusively distributed throughout the sarcolemma, while adult cells have mature IDs with preferentially localized Na+channels and GJs. In this study, we perform an in silico investigation of key age-dependent properties to determine developmental regulation of cardiac conduction. Simulations predict that conduction velocity (CV) biphasically depends on cell size, depending on the strength of GJ coupling. Total cell Na+channel conductance is predictive of CV in cardiac tissue with high GJ coupling, but not correlated with CV for low GJ coupling. We find that ephaptic effects are greatest for larger cells with low GJ coupling typically associated with intermediate developmental stages. Finally, simulations illustrate how variability in cellular properties during different developmental stages can result in a range of possible CV values, with a narrow range for both neonatal and adult myocardium but a much wider range for an intermediate developmental stage. Thus, we find that developmental changes predict associated changes in cardiac conduction.
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Affiliation(s)
- Madison B. Nowak
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
- The Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, OH, United States
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
- Virginia Polytechnic Institute and State University, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States
| | - Seth H. Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
- The Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, OH, United States
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22
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Ivanovic E, Kucera JP. Localization of Na + channel clusters in narrowed perinexi of gap junctions enhances cardiac impulse transmission via ephaptic coupling: a model study. J Physiol 2021; 599:4779-4811. [PMID: 34533834 PMCID: PMC9293295 DOI: 10.1113/jp282105] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/06/2021] [Indexed: 01/06/2023] Open
Abstract
Abstract It has been proposed that when gap junctional coupling is reduced in cardiac tissue, action potential propagation can be supported via ephaptic coupling, a mechanism mediated by negative electric potentials occurring in narrow intercellular clefts of intercalated discs (IDs). Recent studies showed that sodium (Na+) channels form clusters near gap junction plaques in nanodomains called perinexi, where the ID cleft is even narrower. To examine the electrophysiological relevance of Na+ channel clusters being located in perinexi, we developed a 3D finite element model of two longitudinally abutting cardiomyocytes, with a central Na+ channel cluster on the ID membranes. When this cluster was located in the perinexus of a closely positioned gap junction plaque, varying perinexal width greatly modulated impulse transmission from one cell to the other, with narrow perinexi potentiating ephaptic coupling. This modulation occurred via the interplay of Na+ currents, extracellular potentials in the cleft and patterns of current flow within the cleft. In contrast, when the Na+ channel cluster was located remotely from the gap junction plaque, this modulation by perinexus width largely disappeared. Interestingly, the Na+ current in the ID membrane of the pre‐junctional cell switched from inward to outward during excitation, thus contributing ions to the activating channels on the post‐junctional ID membrane. In conclusion, these results indicate that the localization of Na+ channel clusters in the perinexi of gap junction plaques is crucial for ephaptic coupling, which is furthermore greatly modulated by perinexal width. These findings are relevant for a comprehensive understanding of cardiac excitation. Key points Ephaptic coupling is a cardiac conduction mechanism involving nanoscale‐level interactions between the sodium (Na+) current and the extracellular potential in narrow intercalated disc clefts. When gap junctional coupling is reduced, ephaptic coupling acts in conjunction with the classical cardiac conduction mechanism based on gap junctional current flow. In intercalated discs, Na+ channels form clusters that are preferentially located in the periphery of gap junction plaques, in nanodomains known as perinexi, but the electrophysiological role of these perinexi has never been examined. In our new 3D finite element model of two cardiac cells abutting each other with their intercalated discs, a Na+ channel cluster located inside a narrowed perinexus facilitated impulse transmission via ephaptic coupling. Our simulations demonstrate the role of narrowed perinexi as privileged sites for ephaptic coupling in pathological situations when gap junctional coupling is decreased.
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Affiliation(s)
- Ena Ivanovic
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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23
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Dietrichs ES, McGlynn K, Allan A, Connolly A, Bishop M, Burton F, Kettlewell S, Myles R, Tveita T, Smith GL. Moderate but not severe hypothermia causes pro-arrhythmic changes in cardiac electrophysiology. Cardiovasc Res 2021; 116:2081-2090. [PMID: 32031595 PMCID: PMC7584464 DOI: 10.1093/cvr/cvz309] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/08/2019] [Accepted: 02/04/2020] [Indexed: 12/15/2022] Open
Abstract
Aims Treatment of arrhythmias evoked by hypothermia/rewarming remains challenging, and the underlying mechanisms are unclear. This in vitro experimental study assessed cardiac electrophysiology in isolated rabbit hearts at temperatures occurring in therapeutic and accidental hypothermia. Methods and results Detailed ECG, surface electrogram, and panoramic optical mapping were performed in isolated rabbit hearts cooled to moderate (31°C) and severe (17°C) hypothermia. Ventricular activation was unchanged at 31°C while action potential duration (APD) was significantly prolonged (176.9 ± 4.2 ms vs. 241.0 ± 2.9 ms, P < 0.05), as was ventricular repolarization. At 17°C, there were proportionally similar delays in both activation and repolarization. These changes were reflected in the QRS and QT intervals of ECG recordings. Ventricular fibrillation threshold was significantly reduced at 31°C (16.3 ± 3.1 vs. 35 ± 3.5 mA, P < 0.05) but increased at 17°C (64.2 ± 9.9, P < 0.05). At 31°C, transverse conduction was relatively unchanged by cooling compared to longitudinal conduction, but at 17°C both transverse and longitudinal conduction were proportionately reduced to a similar extent. The gap junction uncoupler heptanol had a larger relative effect on transverse than longitudinal conduction and was able to restore the transverse/longitudinal conduction ratio, returning ventricular fibrillation threshold to baseline values (16.3 ± 3.1 vs. 36.3 ± 4.3 mA, P < 0.05) at 31°C. Rewarming to 37°C restored the majority of the electrophysiological parameters. Conclusions Moderate hypothermia does not significantly change ventricular conduction time but prolongs repolarization and is pro-arrhythmic. Further cooling to severe hypothermia causes parallel changes in ventricular activation and repolarization, changes which are anti-arrhythmic. Therefore, relative changes in QRS and QT intervals (QR/QTc) emerge as an ECG-biomarker of pro-arrhythmic activity. Risk for ventricular fibrillation appears to be linked to the relatively low temperature sensitivity of ventricular transmural conduction, a conclusion supported by the anti-arrhythmic effect of heptanol at 31°C.
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Affiliation(s)
- Erik S Dietrichs
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway.,Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Norway.,Divisions of Diagnostic Services and Surgical Medicine and Intensive Care, University Hospital of Northern Norway, Tromsø, Norway
| | - Karen McGlynn
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
| | - Andrew Allan
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
| | - Adam Connolly
- Division of Imaging Sciences & Biomedical Engineering, Department of Biomedical Engineering, Kings College London, UK
| | - Martin Bishop
- Division of Imaging Sciences & Biomedical Engineering, Department of Biomedical Engineering, Kings College London, UK
| | - Francis Burton
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
| | - Sarah Kettlewell
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
| | - Rachel Myles
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Norway.,Divisions of Diagnostic Services and Surgical Medicine and Intensive Care, University Hospital of Northern Norway, Tromsø, Norway
| | - Godfrey L Smith
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, UK
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24
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Deleeuw V, De Clercq A, De Backer J, Sips P. An Overview of Investigational and Experimental Drug Treatment Strategies for Marfan Syndrome. J Exp Pharmacol 2021; 13:755-779. [PMID: 34408505 PMCID: PMC8366784 DOI: 10.2147/jep.s265271] [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: 05/01/2021] [Accepted: 07/19/2021] [Indexed: 12/26/2022] Open
Abstract
Marfan syndrome (MFS) is a heritable connective tissue disorder caused by pathogenic variants in the gene coding for the extracellular matrix protein fibrillin-1. While the disease affects multiple organ systems, the most life-threatening manifestations are aortic aneurysms leading to dissection and rupture. Other cardiovascular complications, including mitral valve prolapse, primary cardiomyopathy, and arrhythmia, also occur more frequently in patients with MFS. The standard medical care relies on cardiovascular imaging at regular intervals, along with pharmacological treatment with β-adrenergic receptor blockers aimed at reducing the aortic growth rate. When aortic dilatation reaches a threshold associated with increased risk of dissection, prophylactic surgical aortic replacement is performed. Although current clinical management has significantly improved the life expectancy of patients with MFS, no cure is available and fatal complications still occur, underscoring the need for new treatment options. In recent years, preclinical studies have identified a number of potentially promising therapeutic targets. Nevertheless, the translation of these results into clinical practice has remained challenging. In this review, we present an overview of the currently available knowledge regarding the underlying pathophysiological processes associated with MFS cardiovascular pathology. We then summarize the treatment options that have been developed based on this knowledge and are currently in different stages of preclinical or clinical development, provide a critical review of the limitations of current studies and highlight potential opportunities for future research.
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Affiliation(s)
- Violette Deleeuw
- Center for Medical Genetics, Department of Biomolecular Medicine, Ghent University, Ghent, 9000, Belgium
| | - Adelbert De Clercq
- Center for Medical Genetics, Department of Biomolecular Medicine, Ghent University, Ghent, 9000, Belgium
| | - Julie De Backer
- Center for Medical Genetics, Department of Biomolecular Medicine, Ghent University, Ghent, 9000, Belgium.,Department of Internal Medicine and Pediatrics, Ghent University Hospital, Ghent, 9000, Belgium
| | - Patrick Sips
- Center for Medical Genetics, Department of Biomolecular Medicine, Ghent University, Ghent, 9000, Belgium
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25
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Kléber AG, Jin Q. Coupling between cardiac cells-An important determinant of electrical impulse propagation and arrhythmogenesis. ACTA ACUST UNITED AC 2021; 2:031301. [PMID: 34296210 DOI: 10.1063/5.0050192] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/09/2021] [Indexed: 01/30/2023]
Abstract
Cardiac arrhythmias are an important cause of sudden cardiac death-a devastating manifestation of many underlying causes, such as heart failure and ischemic heart disease leading to ventricular tachyarrhythmias and ventricular fibrillation, and atrial fibrillation causing cerebral embolism. Cardiac electrical propagation is a main factor in the initiation and maintenance of cardiac arrhythmias. In the heart, gap junctions are the basic unit at the cellular level that host intercellular low-resistance channels for the diffusion of ions and small regulatory molecules. The dual voltage clamp technique enabled the direct measurement of electrical conductance between cells and recording of single gap junction channel openings. The rapid turnover of gap junction channels at the intercalated disk implicates a highly dynamic process of trafficking and internalization of gap junction connexons. Recently, non-canonical roles of gap junction proteins have been discovered in mitochondria function, cytoskeletal organization, trafficking, and cardiac rescue. At the tissue level, we explain the concepts of linear propagation and safety factor based on the model of linear cellular structure. Working myocardium is adequately represented as a discontinuous cellular network characterized by cellular anisotropy and connective tissue heterogeneity. Electrical propagation in discontinuous cellular networks reflects an interplay of three main factors: cell-to-cell electrical coupling, flow of electrical charge through the ion channels, and the microscopic tissue structure. This review provides a state-of-the-art update of the cardiac gap junction channels and their role in cardiac electrical impulse propagation and highlights a combined approach of genetics, cell biology, and physics in modern cardiac electrophysiology.
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Affiliation(s)
- André G Kléber
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Qianru Jin
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, Massachusetts 02134, USA
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26
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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27
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James EC, Tomaskovic-Crook E, Crook JM. Bioengineering Clinically Relevant Cardiomyocytes and Cardiac Tissues from Pluripotent Stem Cells. Int J Mol Sci 2021; 22:ijms22063005. [PMID: 33809429 PMCID: PMC8001925 DOI: 10.3390/ijms22063005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 12/23/2022] Open
Abstract
The regenerative capacity of cardiomyocytes is insufficient to functionally recover damaged tissue, and as such, ischaemic heart disease forms the largest proportion of cardiovascular associated deaths. Human-induced pluripotent stem cells (hiPSCs) have enormous potential for developing patient specific cardiomyocytes for modelling heart disease, patient-based cardiac toxicity testing and potentially replacement therapy. However, traditional protocols for hiPSC-derived cardiomyocytes yield mixed populations of atrial, ventricular and nodal-like cells with immature cardiac properties. New insights gleaned from embryonic heart development have progressed the precise production of subtype-specific hiPSC-derived cardiomyocytes; however, their physiological immaturity severely limits their utility as model systems and their use for drug screening and cell therapy. The long-entrenched challenges in this field are being addressed by innovative bioengingeering technologies that incorporate biophysical, biochemical and more recently biomimetic electrical cues, with the latter having the potential to be used to both direct hiPSC differentiation and augment maturation and the function of derived cardiomyocytes and cardiac tissues by mimicking endogenous electric fields.
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Affiliation(s)
- Emma Claire James
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
| | - Eva Tomaskovic-Crook
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong 2500, Australia
- Correspondence: (E.T.-C.); (J.M.C.)
| | - Jeremy Micah Crook
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong 2500, Australia
- Department of Surgery, St Vincent’s Hospital, The University of Melbourne, Fitzroy 3065, Australia
- Correspondence: (E.T.-C.); (J.M.C.)
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Abstract
The normal physiologic range of QRS complex duration spans between 80 and 125 ms with known differences between females and males which cannot be explained by the anatomical variations of heart sizes. To investigate the reasons for the sex differences as well as for the wide range of normal values, a technology is proposed based on the singular value decomposition and on the separation of different orthogonal components of the QRS complex. This allows classification of the proportions of different components representing the 3-dimensional representation of the electrocardiographic signal as well as classification of components that go beyond the 3-dimensional representation and that correspond to the degree of intricate convolutions of the depolarisation sequence. The technology was applied to 382,019 individual 10-s ECG samples recorded in 639 healthy subjects (311 females and 328 males) aged 33.8 ± 9.4 years. The analyses showed that QRS duration was mainly influenced by the proportions of the first two orthogonal components of the QRS complex. The first component demonstrated statistically significantly larger proportion of the total QRS power (expressed by the absolute area of the complex in all independent ECG leads) in females than in males (64.2 ± 11.6% vs 59.7 ± 11.9%, p < 0.00001—measured at resting heart rate of 60 beats per minute) while the second component demonstrated larger proportion of the QRS power in males compared to females (33.1 ± 11.9% vs 29.6 ± 11.4%, p < 0.001). The analysis also showed that the components attributable to localised depolarisation sequence abnormalities were significantly larger in males compared to females (2.85 ± 1.08% vs 2.42 ± 0.87%, p < 0.00001). In addition to the demonstration of the technology, the study concludes that the detailed convolution of the depolarisation waveform is individual, and that smoother and less intricate depolarisation propagation is the mechanism likely responsible for shorter QRS duration in females.
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29
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Xiao S, Shimura D, Baum R, Hernandez DM, Agvanian S, Nagaoka Y, Katsumata M, Lampe PD, Kleber AG, Hong T, Shaw RM. Auxiliary trafficking subunit GJA1-20k protects connexin-43 from degradation and limits ventricular arrhythmias. J Clin Invest 2021; 130:4858-4870. [PMID: 32525845 DOI: 10.1172/jci134682] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 06/03/2020] [Indexed: 12/31/2022] Open
Abstract
Connexin-43 (Cx43) gap junctions provide intercellular coupling, which ensures rapid action potential propagation and synchronized heart contraction. Alterations in Cx43 localization and reductions in gap junction coupling occur in failing hearts, contributing to ventricular arrhythmias and sudden cardiac death. Recent reports have found that an internally translated Cx43 isoform, GJA1-20k, is an auxiliary subunit for the trafficking of Cx43 in heterologous expression systems. Here, we have created a mouse model by using CRISPR technology to mutate a single internal translation initiation site in Cx43 (M213L mutation), which generates full-length Cx43, but not GJA1-20k. We found that GJA1M213L/M213L mice had severely abnormal electrocardiograms despite preserved contractile function, reduced total Cx43, and reduced gap junctions, and they died suddenly at 2 to 4 weeks of age. Heterozygous GJA1M213L/WT mice survived to adulthood with increased ventricular ectopy. Biochemical experiments indicated that cytoplasmic Cx43 had a half-life that was 50% shorter than membrane-associated Cx43. Without GJA1-20k, poorly trafficked Cx43 was degraded. The data support that GJA1-20k, an endogenous entity translated independently of Cx43, is critical for Cx43 gap junction trafficking, maintenance of Cx43 protein, and normal electrical function of the mammalian heart.
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Affiliation(s)
- Shaohua Xiao
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Neurology, UCLA, Los Angeles, California, USA
| | - Daisuke Shimura
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Rachel Baum
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Diana M Hernandez
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Sosse Agvanian
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Yoshiko Nagaoka
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Makoto Katsumata
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Paul D Lampe
- Translational Research Program, Public Health Sciences and Human Biology Divisions, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Andre G Kleber
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - TingTing Hong
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robin M Shaw
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
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30
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Jæger KH, Charwat V, Wall S, Healy KE, Tveito A. Identifying Drug Response by Combining Measurements of the Membrane Potential, the Cytosolic Calcium Concentration, and the Extracellular Potential in Microphysiological Systems. Front Pharmacol 2021; 11:569489. [PMID: 33628168 PMCID: PMC7898238 DOI: 10.3389/fphar.2020.569489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/16/2020] [Indexed: 01/01/2023] Open
Abstract
Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) offer a new means to study and understand the human cardiac action potential, and can give key insight into how compounds may interact with important molecular pathways to destabilize the electrical function of the heart. Important features of the action potential can be readily measured using standard experimental techniques, such as the use of voltage sensitive dyes and fluorescent genetic reporters to estimate transmembrane potentials and cytosolic calcium concentrations. Using previously introduced computational procedures, such measurements can be used to estimate the current density of major ion channels present in hiPSC-CMs, and how compounds may alter their behavior. However, due to the limitations of optical recordings, resolving the sodium current remains difficult from these data. Here we show that if these optical measurements are complemented with observations of the extracellular potential using multi electrode arrays (MEAs), we can accurately estimate the current density of the sodium channels. This inversion of the sodium current relies on observation of the conduction velocity which turns out to be straightforwardly computed using measurements of extracellular waves across the electrodes. The combined data including the membrane potential, the cytosolic calcium concentration and the extracellular potential further opens up for the possibility of accurately estimating the effect of novel drugs applied to hiPSC-CMs.
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Affiliation(s)
| | - Verena Charwat
- Department of Bioengineering, University of California, Berkeley, CA, United States
| | | | - Kevin E. Healy
- Department of Bioengineering, University of California, Berkeley, CA, United States
- Department of Material Science and Engineering, University of California, Berkeley, CA, United States
| | - Aslak Tveito
- Simula Research Laboratory, Oslo, Norway
- Department of Informatics, University of Oslo, Oslo, Norway
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31
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Herndon C, Astley HC, Owerkowicz T, Fenton FH. Defibrillate You Later, Alligator: Q10 Scaling and Refractoriness Keeps Alligators from Fibrillation. Integr Org Biol 2021; 3:obaa047. [PMID: 33977229 PMCID: PMC8101277 DOI: 10.1093/iob/obaa047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Effective cardiac contraction during each heartbeat relies on the coordination of an electrical wave of excitation propagating across the heart. Dynamically induced heterogeneous wave propagation may fracture and initiate reentry-based cardiac arrhythmias, during which fast-rotating electrical waves lead to repeated self-excitation that compromises cardiac function and potentially results in sudden cardiac death. Species which function effectively over a large range of heart temperatures must balance the many interacting, temperature-sensitive biochemical processes to maintain normal wave propagation at all temperatures. To investigate how these species avoid dangerous states across temperatures, we optically mapped the electrical activity across the surfaces of alligator (Alligator mississippiensis) hearts at 23°C and 38°C over a range of physiological heart rates and compare them with that of rabbits (Oryctolagus cuniculus). We find that unlike rabbits, alligators show minimal changes in wave parameters (action potential duration and conduction velocity) which complement each other to retain similar electrophysiological wavelengths across temperatures and pacing frequencies. The cardiac electrophysiology of rabbits accommodates the high heart rates necessary to sustain an active and endothermic metabolism at the cost of increased risk of cardiac arrhythmia and critical vulnerability to temperature changes, whereas that of alligators allows for effective function over a range of heart temperatures without risk of cardiac electrical arrhythmias such as fibrillation, but is restricted to low heart rates. Synopsis La contracción cardíaca efectiva durante cada latido del corazón depende de la coordinación de una onda eléctrica de excitación que se propaga a través del corazón. Heterogéidades inducidas dinámicamente por ondas de propagación pueden resultar en fracturas de las ondas e iniciar arritmias cardíacas basadas en ondas de reingreso, durante las cuales ondas espirales eléctricas de rotación rápida producen una autoexcitación repetida que afecta la función cardíaca y pude resultar en muerte súbita cardíaca. Las especies que funcionan eficazmente en una amplia gama de temperaturas cardíacas deben equilibrar los varios procesos bioquímicos que interactúan, sensibles a la temperatura para mantener la propagación normal de ondas a todas las temperaturas. Para investigar cómo estas especies evitan los estados peligrosos a través de las temperaturas, mapeamos ópticamente la actividad eléctrica a través de las superficies de los corazones de caimanes (Alligator mississippiensis) a 23°C and 38°C sobre un rango de frecuencias fisiológicas del corazón y comparamos con el de los conejos (Oryctolagus cuniculus). Encontramos que a diferencia de los conejos, los caimanes muestran cambios mínimos en los parámetros de onda (duración potencial de acción y velocidad de conducción) que se complementan entre sí para retener longitudes de onda electrofisiológicas similares a través de los rangos de temperaturas y frecuencias de ritmo. La electrofisiología cardíaca de los conejos acomoda las altas frecuencias cardíacas necesarias para mantener un metabolismo activo y endotérmico a costa de un mayor riesgo de arritmia cardíaca y vulnerabilidad crítica a los cambios de temperatura, mientras que la de los caimanes permite un funcionamiento eficaz en una serie de temperaturas cardíacas sin riesgo de arritmias eléctricas cardíacas como la fibrilación, pero está restringida a bajas frecuencias cardíacas.
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Affiliation(s)
- Conner Herndon
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Henry C Astley
- Department of Biology, Biomimicry Research & Innovation Center, University of Akron, Akron, OH, USA
| | - Tomasz Owerkowicz
- Department of Biology, California State University, San Bernardino, CA, USA
| | - Flavio H Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
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32
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Kotadia I, Whitaker J, Roney C, Niederer S, O’Neill M, Bishop M, Wright M. Anisotropic Cardiac Conduction. Arrhythm Electrophysiol Rev 2020; 9:202-210. [PMID: 33437488 PMCID: PMC7788398 DOI: 10.15420/aer.2020.04] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 10/09/2020] [Indexed: 01/06/2023] Open
Abstract
Anisotropy is the property of directional dependence. In cardiac tissue, conduction velocity is anisotropic and its orientation is determined by myocyte direction. Cell shape and size, excitability, myocardial fibrosis, gap junction distribution and function are all considered to contribute to anisotropic conduction. In disease states, anisotropic conduction may be enhanced, and is implicated, in the genesis of pathological arrhythmias. The principal mechanism responsible for enhanced anisotropy in disease remains uncertain. Possible contributors include changes in cellular excitability, changes in gap junction distribution or function and cellular uncoupling through interstitial fibrosis. It has recently been demonstrated that myocyte orientation may be identified using diffusion tensor magnetic resonance imaging in explanted hearts, and multisite pacing protocols have been proposed to estimate myocyte orientation and anisotropic conduction in vivo. These tools have the potential to contribute to the understanding of the role of myocyte disarray and anisotropic conduction in arrhythmic states.
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Affiliation(s)
- Irum Kotadia
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
- Guy’s and St Thomas’ NHS Foundation Trust, London, UK
| | - John Whitaker
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
- Guy’s and St Thomas’ NHS Foundation Trust, London, UK
| | - Caroline Roney
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
| | - Steven Niederer
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
| | - Mark O’Neill
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
- Guy’s and St Thomas’ NHS Foundation Trust, London, UK
| | - Martin Bishop
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
| | - Matthew Wright
- School of Biomedical Engineering and Imaging Sciences, King’s College, London, UK
- Guy’s and St Thomas’ NHS Foundation Trust, London, UK
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Mezache L, Struckman HL, Greer-Short A, Baine S, Györke S, Radwański PB, Hund TJ, Veeraraghavan R. Vascular endothelial growth factor promotes atrial arrhythmias by inducing acute intercalated disk remodeling. Sci Rep 2020; 10:20463. [PMID: 33235263 PMCID: PMC7687901 DOI: 10.1038/s41598-020-77562-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 11/09/2020] [Indexed: 12/30/2022] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia and is associated with inflammation. AF patients have elevated levels of inflammatory cytokines known to promote vascular leak, such as vascular endothelial growth factor A (VEGF). However, the contribution of vascular leak and consequent cardiac edema to the genesis of atrial arrhythmias remains unknown. Previous work suggests that interstitial edema in the heart can acutely promote ventricular arrhythmias by disrupting ventricular myocyte intercalated disk (ID) nanodomains rich in cardiac sodium channels (NaV1.5) and slowing cardiac conduction. Interestingly, similar disruption of ID nanodomains has been identified in atrial samples from AF patients. Therefore, we tested the hypothesis that VEGF-induced vascular leak can acutely increase atrial arrhythmia susceptibility by disrupting ID nanodomains and slowing atrial conduction. Treatment of murine hearts with VEGF (30–60 min, at clinically relevant levels) prolonged the electrocardiographic P wave and increased susceptibility to burst pacing-induced atrial arrhythmias. Optical voltage mapping revealed slower atrial conduction following VEGF treatment (10 ± 0.4 cm/s vs. 21 ± 1 cm/s at baseline, p < 0.05). Transmission electron microscopy revealed increased intermembrane spacing at ID sites adjacent to gap junctions (GJs; 64 ± 9 nm versus 17 ± 1 nm in controls, p < 0.05), as well as sites next to mechanical junctions (MJs; 63 ± 4 nm versus 27 ± 2 nm in controls, p < 0.05) in VEGF–treated hearts relative to controls. Importantly, super-resolution microscopy and quantitative image analysis revealed reorganization of NaV1.5 away from dense clusters localized near GJs and MJs to a more diffuse distribution throughout the ID. Taken together, these data suggest that VEGF can acutely predispose otherwise normal hearts to atrial arrhythmias by dynamically disrupting NaV1.5-rich ID nanodomains and slowing atrial conduction. These data highlight inflammation-induced vascular leak as a potential factor in the development and progression of AF.
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Affiliation(s)
- Louisa Mezache
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, 460 Medical Center Dr., Rm 415A, IBMR, Columbus, OH, 43210, USA
| | - Heather L Struckman
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, 460 Medical Center Dr., Rm 415A, IBMR, Columbus, OH, 43210, USA
| | - Amara Greer-Short
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Stephen Baine
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Sándor Györke
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Przemysław B Radwański
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA.,Division of Pharmacy Practice and Sciences, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - Thomas J Hund
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, 460 Medical Center Dr., Rm 415A, IBMR, Columbus, OH, 43210, USA.,The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, 460 Medical Center Dr., Rm 415A, IBMR, Columbus, OH, 43210, USA. .,The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA. .,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA.
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Hichri E, Selimi Z, Kucera JP. Modeling the Interactions Between Sodium Channels Provides Insight Into the Negative Dominance of Certain Channel Mutations. Front Physiol 2020; 11:589386. [PMID: 33250780 PMCID: PMC7674773 DOI: 10.3389/fphys.2020.589386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/12/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Nav1.5 cardiac Na+ channel mutations can cause arrhythmogenic syndromes. Some of these mutations exert a dominant negative effect on wild-type channels. Recent studies showed that Na+ channels can dimerize, allowing coupled gating. This leads to the hypothesis that allosteric interactions between Na+ channels modulate their function and that these interactions may contribute to the negative dominance of certain mutations. METHODS To investigate how allosteric interactions affect microscopic and macroscopic channel function, we developed a modeling paradigm in which Markovian models of two channels are combined. Allosteric interactions are incorporated by modifying the free energies of the composite states and/or barriers between states. RESULTS Simulations using two generic 2-state models (C-O, closed-open) revealed that increasing the free energy of the composite states CO/OC leads to coupled gating. Simulations using two 3-state models (closed-open-inactivated) revealed that coupled closings must also involve interactions between further composite states. Using two 6-state cardiac Na+ channel models, we replicated previous experimental results mainly by increasing the energies of the CO/OC states and lowering the energy barriers between the CO/OC and the CO/OO states. The channel model was then modified to simulate a negative dominant mutation (Nav1.5 p.L325R). Simulations of homodimers and heterodimers in the presence and absence of interactions showed that the interactions with the variant channel impair the opening of the wild-type channel and thus contribute to negative dominance. CONCLUSION Our new modeling framework recapitulates qualitatively previous experimental observations and helps identifying possible interaction mechanisms between ion channels.
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Affiliation(s)
| | | | - Jan P. Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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Rusiecka OM, Montgomery J, Morel S, Batista-Almeida D, Van Campenhout R, Vinken M, Girao H, Kwak BR. Canonical and Non-Canonical Roles of Connexin43 in Cardioprotection. Biomolecules 2020; 10:biom10091225. [PMID: 32842488 PMCID: PMC7563275 DOI: 10.3390/biom10091225] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/17/2020] [Accepted: 08/20/2020] [Indexed: 12/15/2022] Open
Abstract
Since the mid-20th century, ischemic heart disease has been the world’s leading cause of death. Developing effective clinical cardioprotection strategies would make a significant impact in improving both quality of life and longevity in the worldwide population. Both ex vivo and in vivo animal models of cardiac ischemia/reperfusion (I/R) injury are robustly used in research. Connexin43 (Cx43), the predominant gap junction channel-forming protein in cardiomyocytes, has emerged as a cardioprotective target. Cx43 posttranslational modifications as well as cellular distribution are altered during cardiac reperfusion injury, inducing phosphorylation states and localization detrimental to maintaining intercellular communication and cardiac conduction. Pre- (before ischemia) and post- (after ischemia but before reperfusion) conditioning can abrogate this injury process, preserving Cx43 and reducing cell death. Pre-/post-conditioning has been shown to largely rely on the presence of Cx43, including mitochondrial Cx43, which is implicated to play a major role in pre-conditioning. Posttranslational modifications of Cx43 after injury alter the protein interactome, inducing negative protein cascades and altering protein trafficking, which then causes further damage post-I/R injury. Recently, several peptides based on the Cx43 sequence have been found to successfully diminish cardiac injury in pre-clinical studies.
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Affiliation(s)
- Olga M. Rusiecka
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Jade Montgomery
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Sandrine Morel
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
| | - Daniela Batista-Almeida
- Univ Coimbra, Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal; (D.B.-A.); (H.G.)
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3000-548 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Raf Van Campenhout
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (R.V.C.); (M.V.)
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, 1090 Brussels, Belgium; (R.V.C.); (M.V.)
| | - Henrique Girao
- Univ Coimbra, Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, 3000-548 Coimbra, Portugal; (D.B.-A.); (H.G.)
- Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), 3000-548 Coimbra, Portugal
- Clinical Academic Centre of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland; (O.M.R.); (J.M.); (S.M.)
- Correspondence:
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Mavroidis M, Athanasiadis NC, Rigas P, Kostavasili I, Kloukina I, Te Rijdt WP, Kavantzas N, Chaniotis D, van Tintelen JP, Skaliora I, Davos CH. Desmin is essential for the structure and function of the sinoatrial node: implications for increased arrhythmogenesis. Am J Physiol Heart Circ Physiol 2020; 319:H557-H570. [PMID: 32678709 DOI: 10.1152/ajpheart.00594.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our objective was to investigate the effect of desmin depletion on the structure and function of the sinoatrial pacemaker complex (SANcl) and its implication in arrhythmogenesis. Analysis of mice and humans (SANcl) indicated that the sinoatrial node exhibits high amounts of desmin, desmoplakin, N-cadherin, and β-catenin in structures we call "lateral intercalated disks" connecting myocytes side by side. Examination of the SANcl from an arrhythmogenic cardiomyopathy model, desmin-deficient (Des-/-) mouse, by immunofluorescence, ultrastructural, and Western blot analysis showed that the number of these lateral intercalated disks was diminished. Also, electrophysiological recordings of the isolated compact sinoatrial node revealed increased pacemaker systolic potential and higher diastolic depolarization rate compared with wild-type mice. Prolonged interatrial conduction expressed as a longer P wave duration was also observed in Des-/- mice. Upregulation of mRNA levels of both T-type Ca2+ current channels, Cav3.1 and Cav3.2, in the Des-/- myocardium (1.8- and 2.3-fold, respectively) and a 1.9-fold reduction of funny hyperpolarization-activated cyclic nucleotide-gated K+ channel 1 could underlie these functional differences. To investigate arrhythmogenicity, electrocardiographic analysis of Des-deficient mice revealed a major increase in supraventricular and ventricular ectopic beats compared with wild-type mice. Heart rate variability analysis indicated a sympathetic predominance in Des-/- mice, which may further contribute to arrhythmogenicity. In conclusion, our results indicate that desmin elimination leads to structural and functional abnormalities of the SANcl. These alterations may be enhanced by the sympathetic component of the cardiac autonomic nervous system, which is predominant in the desmin-deficient heart, thus leading to increased arrhythmogenesis.NEW & NOTEWORTHY The sinoatrial node exhibits high amounts of desmin and desmoplakin in structures we call "lateral intercalated disks," connecting side-by-side adjacent cardiomyocytes. These structures are diminished in desmin-deficient mouse models. Misregulation of T-type Ca2+ current and hyperpolarization-activated cyclic nucleotide-gated K+ channel 1 was proved along with prolonged interatrial conduction and cardiac autonomic nervous system dysfunction.
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Affiliation(s)
- Manolis Mavroidis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Nikolaos C Athanasiadis
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Pavlos Rigas
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Ioanna Kostavasili
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Ismini Kloukina
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Wouter P Te Rijdt
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Experimental Cardiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Nikolaos Kavantzas
- First Department of Pathology, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitris Chaniotis
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - J Peter van Tintelen
- Department of Genetics, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Irini Skaliora
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Constantinos H Davos
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
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Salvage SC, Huang CLH, Jackson AP. Cell-Adhesion Properties of β-Subunits in the Regulation of Cardiomyocyte Sodium Channels. Biomolecules 2020; 10:biom10070989. [PMID: 32630316 PMCID: PMC7407995 DOI: 10.3390/biom10070989] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 12/17/2022] Open
Abstract
Voltage-gated sodium (Nav) channels drive the rising phase of the action potential, essential for electrical signalling in nerves and muscles. The Nav channel α-subunit contains the ion-selective pore. In the cardiomyocyte, Nav1.5 is the main Nav channel α-subunit isoform, with a smaller expression of neuronal Nav channels. Four distinct regulatory β-subunits (β1–4) bind to the Nav channel α-subunits. Previous work has emphasised the β-subunits as direct Nav channel gating modulators. However, there is now increasing appreciation of additional roles played by these subunits. In this review, we focus on β-subunits as homophilic and heterophilic cell-adhesion molecules and the implications for cardiomyocyte function. Based on recent cryogenic electron microscopy (cryo-EM) data, we suggest that the β-subunits interact with Nav1.5 in a different way from their binding to other Nav channel isoforms. We believe this feature may facilitate trans-cell-adhesion between β1-associated Nav1.5 subunits on the intercalated disc and promote ephaptic conduction between cardiomyocytes.
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Affiliation(s)
- Samantha C. Salvage
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Correspondence: (S.C.S.); (A.P.J.); Tel.: +44-1223-765950 (S.C.S.); +44-1223-765951 (A.P.J.)
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Antony P. Jackson
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Correspondence: (S.C.S.); (A.P.J.); Tel.: +44-1223-765950 (S.C.S.); +44-1223-765951 (A.P.J.)
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Jiang W, Hu X, Li F, Li G, Wang Y. Adrenoceptor Responses in Human Embryonic Stem Cell-Derived Cardiomyocytes: a Special Focus on Electrophysiological Property. J Pharmacol Exp Ther 2020; 373:429-437. [PMID: 32217769 DOI: 10.1124/jpet.120.265686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/19/2020] [Indexed: 01/16/2023] Open
Abstract
Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) have become a promising cell source for cardiovascular research. The electrophysiological characteristic of hESC-CMs has been generally studied, but little is known about electrophysiological response to adrenergic receptor (AR) activation. This study aims to characterize electrophysiological response of hESC-CMs to adrenergic stimulation in terms of the conduction velocity (CV) and action potential (AP) shape. The H9 hESC-CMs were acquired by a classic differentiation protocol and cultured to achieve confluent cell monolayers. The AP shape and CV among the monolayers were recorded using optical mapping during electrophysiological and pharmacological stimulation experiments. Quantitative real-time polymerase chain reaction and Western blot were adopted to determine the expression levels of Connexin and ion channel gene and protein. Chronic β-AR stimulation by isoproterenol for 24 hours in hESC-CM monolayers increased CV by approximately 50%, whereas α-AR or acute β-AR stimulation had no significant effect; chronic β-AR stimulation resulted in a significant Connexin (Cx) 43 and Nav1.5 upregulation at both protein and mRNA level. Isoproterenol-induced CV accelerating and Cx43 and Nav1.5 upregulation in hESC-CMs, which was attenuated by selective β1-adrenoceptor antagonist CGP 20712A but not selective β2-antagonist ICI 118551. Moreover, pretreatment with protein kinase A (PKA) inhibitor H89, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (MEK) inhibitor SB203580, and MAPK inhibitor PD98059 suppressed the isoproterenol-induced CV accelerating and Cx43 upregulation, whereas it had no significant effect on Nav1.5 upregulation. The AP shape in hESC-CM monolayers was less susceptible by either β-AR or α-AR stimulation. It was β1-AR not β2-AR contributing to the modification of conduction velocity among hESC-CM monolayers. Chronic β1-AR stimulation accelerates CV by upregulating Cx43 via PKA/MEK/MAPK pathway. SIGNIFICANCE STATEMENT: These data provide new insight into the electrophysiological characteristics of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and depict a concise signaling pathway in the adrenergic receptor (AR) regulation of action potential shape and electrical propagation across hESC-CM monolayer. It is β1-AR not β2-AR contributing to the modification of conduction velocity in hESC-CMs and accelerating conduction velocity by upregulating Connexin 43 via protein kinase A/ mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase/MAPK pathway.
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Affiliation(s)
- Weiwei Jiang
- Departments of Cardiovascular Surgery (X.H., F.L., G.L., Y.W.) and Gastroenterology (W.J.), Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; and Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland (Y.W.)
| | - Xingjian Hu
- Departments of Cardiovascular Surgery (X.H., F.L., G.L., Y.W.) and Gastroenterology (W.J.), Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; and Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland (Y.W.)
| | - Fei Li
- Departments of Cardiovascular Surgery (X.H., F.L., G.L., Y.W.) and Gastroenterology (W.J.), Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; and Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland (Y.W.)
| | - Geng Li
- Departments of Cardiovascular Surgery (X.H., F.L., G.L., Y.W.) and Gastroenterology (W.J.), Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; and Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland (Y.W.)
| | - Yin Wang
- Departments of Cardiovascular Surgery (X.H., F.L., G.L., Y.W.) and Gastroenterology (W.J.), Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; and Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland (Y.W.)
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Real-Time In Vivo Imaging of Mouse Left Ventricle Reveals Fluctuating Movements of the Intercalated Discs. NANOMATERIALS 2020; 10:nano10030532. [PMID: 32188039 PMCID: PMC7153594 DOI: 10.3390/nano10030532] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/24/2022]
Abstract
Myocardial contraction is initiated by action potential propagation through the conduction system of the heart. It has been thought that connexin 43 in the gap junctions (GJ) within the intercalated disc (ID) provides direct electric connectivity between cardiomyocytes (electronic conduction). However, recent studies challenge this view by providing evidence that the mechanosensitive cardiac sodium channels Nav1.5 localized in perinexii at the GJ edge play an important role in spreading action potentials between neighboring cells (ephaptic conduction). In the present study, we performed real-time confocal imaging of the CellMask-stained ID in the living mouse heart in vivo. We found that the ID structure was not rigid. Instead, we observed marked flexing of the ID during propagation of contraction from cell to cell. The variation in ID length was between ~30 and ~42 μm (i.e., magnitude of change, ~30%). In contrast, tracking of α-actinin-AcGFP revealed a comparatively small change in the lateral dimension of the transitional junction near the ID (i.e., magnitude of change, ~20%). The present findings suggest that, when the heart is at work, mechanostress across the perinexii may activate Nav1.5 by promoting ephaptic conduction in coordination with electronic conduction, and, thereby, efficiently transmitting excitation-contraction coupling between cardiomyocytes.
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Zaitsev AV, Warren M. "Heart Oddity": Intrinsically Reduced Excitability in the Right Ventricle Requires Compensation by Regionally Specific Stress Kinase Function. Front Physiol 2020; 11:86. [PMID: 32132931 PMCID: PMC7040197 DOI: 10.3389/fphys.2020.00086] [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: 10/14/2019] [Accepted: 01/27/2020] [Indexed: 11/13/2022] Open
Abstract
The traditional view of ventricular excitation and conduction is an all-or-nothing response mediated by a regenerative activation of the inward sodium channel, which gives rise to an essentially constant conduction velocity (CV). However, whereas there is no obvious biological need to tune-up ventricular conduction, the principal molecular components determining CV, such as sodium channels, inward-rectifier potassium channels, and gap junctional channels, are known targets of the “stress” protein kinases PKA and calcium/calmodulin dependent protein kinase II (CaMKII), and are thus regulatable by signal pathways converging on these kinases. In this mini-review we will expose deficiencies and controversies in our current understanding of how ventricular conduction is regulated by stress kinases, with a special focus on the chamber-specific dimension in this regulation. In particular, we will highlight an odd property of cardiac physiology: uniform CV in ventricles requires co-existence of mutually opposing gradients in cardiac excitability and stress kinase function. While the biological advantage of this peculiar feature remains obscure, it is important to recognize the clinical implications of this phenomenon pertinent to inherited or acquired conduction diseases and therapeutic interventions modulating activity of PKA or CaMKII.
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Affiliation(s)
- Alexey V Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
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Iyer R, Monfredi O, Lavorato M, Terasaki M, Franzini‐Armstrong C. Ultrastructure of primary pacemaking cells in rabbit sino-atrial node cells indicates limited sarcoplasmic reticulum content. FASEB Bioadv 2020; 2:106-115. [PMID: 32123860 PMCID: PMC7003656 DOI: 10.1096/fba.2018-00079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 12/20/2018] [Accepted: 11/25/2019] [Indexed: 11/21/2022] Open
Abstract
The main mammalian heart pacemakers are spindle-shaped cells compressed into tangles within protective layers of collagen in the sino-atrial node (SAN). Two cell types, "dark" and "light," differ on their high or low content of intermediate filaments, but share scarcity of myofibrils and a high content of glycogen. Sarcoplasmic reticulum (SR) is scarce. The free SR (fSR) occupies 0.04% of the cell volume within ~0.4 µm wide peripheral band. The junctional SR (jSR), constituting peripheral couplings (PCs), occupies 0.03% of the cell volume. Total fSR + jSR volume is 0.07% of cell volume, lower than the SR content of ventricular myocytes. The average distance between PCs is 7.6 µm along the periphery. On the average, 30% of the SAN cells surfaces is in close proximity to others. Identifiable gap junctions are extremely rare, but small sites of close membrane-to-membrane contacts are observed. Possibly communication occurs via these very small sites of contact if conducting channels (connexons) are located within them. There is no obvious anatomical detail that might support ephaptic coupling. These observations have implications for understanding of SAN cell physiology, and require incorporation into biophysically detailed models of SAN cell behavior that currently do not include such features.
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Affiliation(s)
- Ramesh Iyer
- Division of CardiologyChildren Hospital of PhiladelphiaPhiladelphiaPAUSA
| | - Oliver Monfredi
- Laboratory of Cardiovascular SciencesNIA IRP NIHBaltimoreMDUSA
- The Johns Hopkins HospitalDepartment of CardiologyBaltimoreMDUSA
| | - Manuela Lavorato
- Department of Cell and Developmental BiologyUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Mark Terasaki
- Department of Cell BiologyUniversity of Connecticut Health CenterFarmingtonCTUSA
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Jæger KH, Edwards AG, McCulloch A, Tveito A. Properties of cardiac conduction in a cell-based computational model. PLoS Comput Biol 2019; 15:e1007042. [PMID: 31150383 PMCID: PMC6561587 DOI: 10.1371/journal.pcbi.1007042] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 06/12/2019] [Accepted: 04/23/2019] [Indexed: 11/18/2022] Open
Abstract
The conduction of electrical signals through cardiac tissue is essential for maintaining the function of the heart, and conduction abnormalities are known to potentially lead to life-threatening arrhythmias. The properties of cardiac conduction have therefore been the topic of intense study for decades, but a number of questions related to the mechanisms of conduction still remain unresolved. In this paper, we demonstrate how the so-called EMI model may be used to study some of these open questions. In the EMI model, the extracellular space, the cell membrane, the intracellular space and the cell connections are all represented as separate parts of the computational domain, and the model therefore allows for study of local properties that are hard to represent in the classical homogenized bidomain or monodomain models commonly used to study cardiac conduction. We conclude that a non-uniform sodium channel distribution increases the conduction velocity and decreases the time delays over gap junctions of reduced coupling in the EMI model simulations. We also present a theoretical optimal cell length with respect to conduction velocity and consider the possibility of ephaptic coupling (i.e. cell-to-cell coupling through the extracellular potential) acting as an alternative or supporting mechanism to gap junction coupling. We conclude that for a non-uniform distribution of sodium channels and a sufficiently small intercellular distance, ephaptic coupling can influence the dynamics of the sodium channels and potentially provide cell-to-cell coupling when the gap junction connection is absent. The electrochemical wave traversing the heart during every beat is essential for cardiac pumping function and supply of blood to the body. Understanding the stability of this wave is crucial to understanding how lethal arrhythmias are generated. Despite this importance, our knowledge of the physical determinants of wave propagation are still evolving. One particular challenge has been the lack of accurate mathematical models of conduction at the cellular level. Because cardiac muscle is an electrical syncytium, in which direct charge transfer between cells drives wave propagation, classical bidomain and monodomain tissue models employ a homogenized approximation of this process. This approximation is not valid at the length scale of single cells, and prevents any analysis of how cellular structures impact cardiac conduction. Instead, so-called microdomain models must be used for these questions. Here we utilize a recently developed modelling framework that is well suited to represent small collections of cells. By applying this framework, we show that concentration of sodium channels at the longitudinal borders of myocytes accelerates cardiac conduction. We also demonstrate that when juxtaposed cells are sufficiently close, this non-uniform distribution induces large ephaptic currents, which contribute to intercellular coupling.
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Affiliation(s)
| | | | - Andrew McCulloch
- Department of Bioengineering, University of California, San Diego, California, United States of America
| | - Aslak Tveito
- Simula Research Laboratory, Oslo, Norway
- * E-mail:
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43
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Salvarani N, Crasto S, Miragoli M, Bertero A, Paulis M, Kunderfranco P, Serio S, Forni A, Lucarelli C, Dal Ferro M, Larcher V, Sinagra G, Vezzoni P, Murry CE, Faggian G, Condorelli G, Di Pasquale E. The K219T-Lamin mutation induces conduction defects through epigenetic inhibition of SCN5A in human cardiac laminopathy. Nat Commun 2019; 10:2267. [PMID: 31118417 PMCID: PMC6531493 DOI: 10.1038/s41467-019-09929-w] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 04/06/2019] [Indexed: 12/14/2022] Open
Abstract
Mutations in LMNA, which encodes the nuclear proteins Lamin A/C, can cause cardiomyopathy and conduction disorders. Here, we employ induced pluripotent stem cells (iPSCs) generated from human cells carrying heterozygous K219T mutation on LMNA to develop a disease model. Cardiomyocytes differentiated from these iPSCs, and which thus carry K219T-LMNA, have altered action potential, reduced peak sodium current and diminished conduction velocity. Moreover, they have significantly downregulated Nav1.5 channel expression and increased binding of Lamin A/C to the promoter of SCN5A, the channel's gene. Coherently, binding of the Polycomb Repressive Complex 2 (PRC2) protein SUZ12 and deposition of the repressive histone mark H3K27me3 are increased at SCN5A. CRISPR/Cas9-mediated correction of the mutation re-establishes sodium current density and SCN5A expression. Thus, K219T-LMNA cooperates with PRC2 in downregulating SCN5A, leading to decreased sodium current density and slower conduction velocity. This mechanism may underlie the conduction abnormalities associated with LMNA-cardiomyopathy.
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Affiliation(s)
- Nicolò Salvarani
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Silvia Crasto
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Michele Miragoli
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
- Department of Medicine and Surgery, University of Parma, Parma, 43121, Italy
| | - Alessandro Bertero
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, 98109, WA, USA
| | - Marianna Paulis
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Paolo Kunderfranco
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Simone Serio
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Alberto Forni
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Carla Lucarelli
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Matteo Dal Ferro
- Cardiovascular Department, "Ospedali Riuniti" and University of Trieste, Trieste, 34129, Italy
| | - Veronica Larcher
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Gianfranco Sinagra
- Cardiovascular Department, "Ospedali Riuniti" and University of Trieste, Trieste, 34129, Italy
| | - Paolo Vezzoni
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Charles E Murry
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, 98109, WA, USA
| | - Giuseppe Faggian
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Gianluigi Condorelli
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy.
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy.
- Humanitas University, Rozzano (MI), 20089, Italy.
| | - Elisa Di Pasquale
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy.
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy.
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Blazeski A, Lowenthal J, Zhu R, Ewoldt J, Boheler KR, Tung L. Functional Properties of Engineered Heart Slices Incorporating Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Stem Cell Reports 2019; 12:982-995. [PMID: 31056480 PMCID: PMC6524004 DOI: 10.1016/j.stemcr.2019.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/18/2022] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great promise for cardiac studies, but their structural and functional immaturity precludes their use as faithful models of adult myocardium. Here we describe engineered heart slices (EHS), preparations of decellularized porcine myocardium repopulated with hiPSC-CMs that exhibit structural and functional improvements over standard culture. EHS exhibited multicellular, aligned bundles of elongated CMs with organized sarcomeres, positive inotropic responses to isoproterenol, anisotropic conduction of action potentials, and electrophysiological functionality for more than 200 days. We developed a new drug assay, GRIDS, that serves as a "fingerprint" of cardiac drug sensitivity for a range of pacing rates and drug concentrations. GRIDS maps characterized differences in drug sensitivity between EHS and monolayers more clearly than changes in action potential durations or conduction velocities. EHS represent a tissue-like model for long-term culture, structural, and functional improvement, and higher fidelity drug response of hiPSC-CMs.
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Affiliation(s)
- Adriana Blazeski
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA
| | - Justin Lowenthal
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA
| | - Renjun Zhu
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jourdan Ewoldt
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kenneth R Boheler
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA; Stem Cell and Regenerative Medicine Consortium, LKS Faculty of Medicine, Hong Kong University, Hong Kong, SAR; Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Leslie Tung
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21205, USA.
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45
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Gourdie RG. The Cardiac Gap Junction has Discrete Functions in Electrotonic and Ephaptic Coupling. Anat Rec (Hoboken) 2018; 302:93-100. [PMID: 30565418 DOI: 10.1002/ar.24036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 07/10/2018] [Accepted: 07/17/2018] [Indexed: 12/31/2022]
Abstract
Connexin43-formed gap junctions have long been thought to contribute to cardiac conduction in the mammalian ventricle by providing direct electrotonic connectivity between the cytoplasms of neighboring cardiomyocytes. However, accumulating data from studies of non-mammalian hearts, Connexin 43 (Cx43) knockout mice and human Cx43 mutations have raised questions as to whether gap junctions are the sole means by which electrical coupling between cardiomyocytes is accomplished. Computational and experimental work over the last decade have indicated that intercellular propagation of action potentials in the heart may involve both electrotonic and ephaptic contributions-in what has been dubbed "mixed-mode" conduction. Interestingly, the Cx43 gap junction may provide a common structural platform in mammals that facilitates the operation of these two mechanisms. In addition to gap junction channels functioning in an electrotonic role, the perinexus region at the edge of gap junctions may be provide a niche for voltage-gated sodium channels from neighboring cells to be in sufficiently close proximity to enable ephaptic transmission of action potential. A novel role has recently been identified in this potential ephaptic mechanism for inter-membrane adhesion mediated by the beta subunit (beta1/Scn1b) of the sodium channel. The new perspective of the operational redundancy that is built into cardiac electrical connectivity could provide new understanding of arrhythmia mechanisms and holds the promise for new approach to anti-arrhythmic therapy. Anat Rec, 302:93-100, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Robert G Gourdie
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke, Virginia, 24016.,Department of Emergency Medicine, Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, Virginia, 24016.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, 24061
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46
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Abstract
As the physiology of synapses began to be explored in the 1950s, it became clear that electrical communication between neurons could not always be explained by chemical transmission. Instead, careful studies pointed to a direct intercellular pathway of current flow and to the anatomical structure that was (eventually) called the gap junction. The mechanism of intercellular current flow was simple compared with chemical transmission, but the consequences of electrical signaling in excitable tissues were not. With the recognition that channels were a means of passive ion movement across membranes, the character and behavior of gap junction channels came under scrutiny. It became evident that these gated channels mediated intercellular transfer of small molecules as well as atomic ions, thereby mediating chemical, as well as electrical, signaling. Members of the responsible protein family in vertebrates-connexins-were cloned and their channels studied by many of the increasingly biophysical techniques that were being applied to other channels. As described here, much of the evolution of the field, from electrical coupling to channel structure-function, has appeared in the pages of the Journal of General Physiology.
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Affiliation(s)
- Andrew L Harris
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ
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47
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The role of the gap junction perinexus in cardiac conduction: Potential as a novel anti-arrhythmic drug target. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:41-50. [PMID: 30241906 DOI: 10.1016/j.pbiomolbio.2018.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/09/2018] [Accepted: 08/10/2018] [Indexed: 12/16/2022]
Abstract
Cardiovascular disease remains the single largest cause of natural death in the United States, with a significant cause of mortality associated with cardiac arrhythmias. Presently, options for treating and preventing myocardial electrical dysfunction, including sudden cardiac death, are limited. Recent studies have indicated that conduction of electrical activation in the heart may have an ephaptic component, wherein intercellular coupling occurs via electrochemical signaling across narrow extracellular clefts between cardiomyocytes. The perinexus is a 100-200 nm-wide stretch of closely apposed membrane directly adjacent to connexin 43 gap junctions. Electron and super-resolution microscopy studies, as well as biochemical analyses, have provided evidence that perinexal nanodomains may be candidate structures for facilitating ephaptic coupling. This work has included characterization of the perinexus as a region of close inter-membrane contact between cardiomyocytes (<30 nm) containing dense clusters of voltage-gated sodium channels. Here, we review what is known about perinexal structure and function and the potential that the perinexus may have novel and pivotal roles in disorders of cardiac conduction. Of particular interest is the prospect that cell adhesion mediated by the cardiac sodium channel β subunit (Scn1b) may be a novel anti-arrhythmic target.
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48
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Radwański PB, Johnson CN, Györke S, Veeraraghavan R. Cardiac Arrhythmias as Manifestations of Nanopathies: An Emerging View. Front Physiol 2018; 9:1228. [PMID: 30233404 PMCID: PMC6131669 DOI: 10.3389/fphys.2018.01228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022] Open
Abstract
A nanodomain is a collection of proteins localized within a specialized, nanoscale structural environment, which can serve as the functional unit of macroscopic physiologic processes. We are beginning to recognize the key roles of cardiomyocyte nanodomains in essential processes of cardiac physiology such as electrical impulse propagation and excitation–contraction coupling (ECC). There is growing appreciation of nanodomain dysfunction, i.e., nanopathy, as a mechanistic driver of life-threatening arrhythmias in a variety of pathologies. Here, we offer an overview of current research on the role of nanodomains in cardiac physiology with particular emphasis on: (1) sodium channel-rich nanodomains within the intercalated disk that participate in cell-to-cell electrical coupling and (2) dyadic nanodomains located along transverse tubules that participate in ECC. The beat to beat function of cardiomyocytes involves three phases: the action potential, the calcium transient, and mechanical contraction/relaxation. In all these phases, cell-wide function results from the aggregation of the stochastic function of individual proteins. While it has long been known that proteins that exist in close proximity influence each other’s function, it is increasingly appreciated that there exist nanoscale structures that act as functional units of cardiac biophysical phenomena. Termed nanodomains, these structures are collections of proteins, localized within specialized nanoscale structural environments. The nano-environments enable the generation of localized electrical and/or chemical gradients, thereby conferring unique functional properties to these units. Thus, the function of a nanodomain is determined by its protein constituents as well as their local structural environment, adding an additional layer of complexity to cardiac biology and biophysics. However, with the emergence of experimental techniques that allow direct investigation of structure and function at the nanoscale, our understanding of cardiac physiology and pathophysiology at these scales is rapidly advancing. Here, we will discuss the structure and functions of multiple cardiomyocyte nanodomains, and novel strategies that target them for the treatment of cardiac arrhythmias.
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Affiliation(s)
- Przemysław B Radwański
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States.,Division of Pharmacy Practice and Science, College of Pharmacy, The Ohio State University, Columbus, OH, United States
| | - Christopher N Johnson
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, United States
| | - Sándor Györke
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Rengasayee Veeraraghavan
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States.,Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
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49
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Yeo JM, Tse V, Kung J, Lin HY, Lee YT, Kwan J, Yan BP, Tse G. Isolated heart models for studying cardiac electrophysiology: a historical perspective and recent advances. J Basic Clin Physiol Pharmacol 2018; 28:191-200. [PMID: 28063261 DOI: 10.1515/jbcpp-2016-0110] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/12/2016] [Indexed: 01/25/2023]
Abstract
Experimental models used in cardiovascular research range from cellular to whole heart preparations. Isolated whole hearts show higher levels of structural and functional integration than lower level models such as tissues or cellular fragments. Cardiovascular diseases are multi-factorial problems that are dependent on highly organized structures rather than on molecular or cellular components alone. This article first provides a general introduction on the animal models of cardiovascular diseases. It is followed by a detailed overview and a historical perspective of the different isolated heart systems with a particular focus on the Langendorff perfusion method for the study of cardiac arrhythmias. The choice of species, perfusion method, and perfusate composition are discussed in further detail with particular considerations of the theoretical and practical aspects of experimental settings.
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Affiliation(s)
- Jie Ming Yeo
- School of Medicine, Imperial College London, London
| | - Vivian Tse
- Department of Physiology, McGill University, Montreal, Quebec
| | - Judy Kung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Hiu Yu Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Yee Ting Lee
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Joseph Kwan
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Bryan P Yan
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne
| | - Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R
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50
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Kim HS, Yoon JW, Li H, Jeong GO, Park JJ, Shin SE, Jang IH, Kim JH, Park WS. Functional expression and pharmaceutical efficacy of cardiac-specific ion channels in human embryonic stem cell-derived cardiomyocytes. Sci Rep 2017; 7:13821. [PMID: 29062050 PMCID: PMC5653792 DOI: 10.1038/s41598-017-14198-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/21/2017] [Indexed: 01/08/2023] Open
Abstract
Cardiomyocytes differentiated from human pluripotent stem cells provide promising tools for screening of cardiotoxic drugs. For evaluation of human pluripotent stem cell-derived cardiomyocytes for cardiotoxicity test, in the present study, human embryonic stem cells (hESCs) were differentiated to cardiomyocytes, followed by metabolic selection to enrich the differentiated cardiomyocytes. The highly purified hESC-derived cardiomyocytes (hESC-CMs) expressed several cardiomyocyte-specific markers including cTnT, MLC2a, and α-SA, but not pluripotency markers, such as OCT4 and NANOG. Patch clamp technique and RT-PCR revealed the expression of cardiomyocyte-specific Na+, Ca2+, and K+ channels and cardiac action potential in hESC-CMs. To explore the potential use of hESC-CMs as functional cardiomyocytes for drug discovery and cardiotoxicity screening, we examined the effects of bisindolylmaleimide (BIM) (I), which inhibits native cardiac Ca2+ channels, on the Ca2+ channel activity of hESC-CMs. We observed a similar response for the BIM (I)-induced modulation of Ca2+ channels between hESC-CMs and native cardiomyocytes through L-type Ca2+ channel current. These results suggest that hESC-CMs can be useful for evaluation of pharmaceutical efficacy and safety of novel drug candidate in cardiac research.
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Affiliation(s)
- Han Sol Kim
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, Republic of Korea
| | - Jung Won Yoon
- Department of Physiology, School of Medicine, Pusan National University, Yangsan, 50612, Republic of Korea
| | - Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, Republic of Korea
| | - Geun Ok Jeong
- Department of Physiology, School of Medicine, Pusan National University, Yangsan, 50612, Republic of Korea
| | - Jin Ju Park
- Department of Physiology, School of Medicine, Pusan National University, Yangsan, 50612, Republic of Korea
| | - Sung Eun Shin
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, Republic of Korea
| | - Il Ho Jang
- Department of Oral Biochemistry and Molecular Biology, Pusan National University School of Dentistry, Yangsan, 50612, Republic of Korea
| | - Jae Ho Kim
- Department of Physiology, School of Medicine, Pusan National University, Yangsan, 50612, Republic of Korea. .,Research Institute of Convergence Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, 50612, Republic of Korea.
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, Republic of Korea.
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