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Stevens TL, Coles S, Sturm AC, Hoover CA, Borzok MA, Mohler PJ, El Refaey M. Molecular Pathways and Animal Models of Arrhythmias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:1057-1090. [PMID: 38884769 DOI: 10.1007/978-3-031-44087-8_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Arrhythmias account for over 300,000 annual deaths in the United States, and approximately half of all deaths are associated with heart disease. Mechanisms underlying arrhythmia risk are complex; however, work in humans and animal models over the past 25 years has identified a host of molecular pathways linked with both arrhythmia substrates and triggers. This chapter will focus on select arrhythmia pathways solved by linking human clinical and genetic data with animal models.
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Affiliation(s)
- Tyler L Stevens
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sara Coles
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Amy C Sturm
- Genomic Medicine Institute, 23andMe, Sunnyvale, CA, USA
| | - Catherine A Hoover
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Maegen A Borzok
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
| | - Peter J Mohler
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mona El Refaey
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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2
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Soda T, Brunetti V, Berra-Romani R, Moccia F. The Emerging Role of N-Methyl-D-Aspartate (NMDA) Receptors in the Cardiovascular System: Physiological Implications, Pathological Consequences, and Therapeutic Perspectives. Int J Mol Sci 2023; 24:ijms24043914. [PMID: 36835323 PMCID: PMC9965111 DOI: 10.3390/ijms24043914] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are ligand-gated ion channels that are activated by the neurotransmitter glutamate, mediate the slow component of excitatory neurotransmission in the central nervous system (CNS), and induce long-term changes in synaptic plasticity. NMDARs are non-selective cation channels that allow the influx of extracellular Na+ and Ca2+ and control cellular activity via both membrane depolarization and an increase in intracellular Ca2+ concentration. The distribution, structure, and role of neuronal NMDARs have been extensively investigated and it is now known that they also regulate crucial functions in the non-neuronal cellular component of the CNS, i.e., astrocytes and cerebrovascular endothelial cells. In addition, NMDARs are expressed in multiple peripheral organs, including heart and systemic and pulmonary circulations. Herein, we survey the most recent information available regarding the distribution and function of NMDARs within the cardiovascular system. We describe the involvement of NMDARs in the modulation of heart rate and cardiac rhythm, in the regulation of arterial blood pressure, in the regulation of cerebral blood flow, and in the blood-brain barrier (BBB) permeability. In parallel, we describe how enhanced NMDAR activity could promote ventricular arrhythmias, heart failure, pulmonary artery hypertension (PAH), and BBB dysfunction. Targeting NMDARs could represent an unexpected pharmacological strategy to reduce the growing burden of several life-threatening cardiovascular disorders.
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Affiliation(s)
- Teresa Soda
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy
| | - Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy
- Correspondence: ; Tel.: +39-0382-987613
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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4
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Papanikolaou M, Crump SM, Abbott GW. The focal adhesion protein Testin modulates KCNE2 potassium channel β subunit activity. Channels (Austin) 2021; 15:229-238. [PMID: 33464998 PMCID: PMC7833772 DOI: 10.1080/19336950.2021.1874119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/25/2022] Open
Abstract
Coronary Artery Disease (CAD) typically kills more people globally each year than any other single cause of death. A better understanding of genetic predisposition to CAD and the underlying mechanisms will help to identify those most at risk and contribute to improved therapeutic approaches. KCNE2 is a functionally versatile, ubiquitously expressed potassium channel β subunit associated with CAD and cardiac arrhythmia susceptibility in humans and mice. Here, to identify novel KCNE2 interaction partners, we employed yeast two-hybrid screening of adult and fetal human heart libraries using the KCNE2 intracellular C-terminal domain as bait. Testin (encoded by TES), an endothelial cell-expressed, CAD-associated, focal adhesion protein, was identified as a high-confidence interaction partner for KCNE2. We confirmed physical association between KCNE2 and Testin in vitro by co-immunoprecipitation. Whole-cell patch clamp electrophysiology revealed that KCNE2 negative-shifts the voltage dependence and increases the rate of activation of the endothelial cell and cardiomyocyte-expressed Kv channel α subunit, Kv1.5 in CHO cells, whereas Testin did not alter Kv1.5 function. However, Testin nullified KCNE2 effects on Kv1.5 voltage dependence and gating kinetics. In contrast, Testin did not prevent KCNE2 regulation of KCNQ1 gating. The data identify a novel role for Testin as a tertiary ion channel regulatory protein. Future studies will address the potential role for KCNE2-Testin interactions in arterial and myocyte physiology and CAD.
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Affiliation(s)
- Maria Papanikolaou
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Shawn M. Crump
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W. Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
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5
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Fluorescence Fluctuation Spectroscopy enables quantification of potassium channel subunit dynamics and stoichiometry. Sci Rep 2021; 11:10719. [PMID: 34021177 PMCID: PMC8140153 DOI: 10.1038/s41598-021-90002-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/15/2021] [Indexed: 11/08/2022] Open
Abstract
Voltage-gated potassium (Kv) channels are a family of membrane proteins that facilitate K+ ion diffusion across the plasma membrane, regulating both resting and action potentials. Kv channels comprise four pore-forming α subunits, each with a voltage sensing domain, and they are regulated by interaction with β subunits such as those belonging to the KCNE family. Here we conducted a comprehensive biophysical characterization of stoichiometry and protein diffusion across the plasma membrane of the epithelial KCNQ1-KCNE2 complex, combining total internal reflection fluorescence (TIRF) microscopy and a series of complementary Fluorescence Fluctuation Spectroscopy (FFS) techniques. Using this approach, we found that KCNQ1-KCNE2 has a predominant 4:4 stoichiometry, while non-bound KCNE2 subunits are mostly present as dimers in the plasma membrane. At the same time, we identified unique spatio-temporal diffusion modalities and nano-environment organization for each channel subunit. These findings improve our understanding of KCNQ1-KCNE2 channel function and suggest strategies for elucidating the subunit stoichiometry and forces directing localization and diffusion of ion channel complexes in general.
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Abstract
Kv7 channels (Kv7.1-7.5) are voltage-gated K+ channels that can be modulated by five β-subunits (KCNE1-5). Kv7.1-KCNE1 channels produce the slow-delayed rectifying K+ current, IKs, which is important during the repolarization phase of the cardiac action potential. Kv7.2-7.5 are predominantly neuronally expressed and constitute the muscarinic M-current and control the resting membrane potential in neurons. Kv7.1 produces drastically different currents as a result of modulation by KCNE subunits. This flexibility allows the Kv7.1 channel to have many roles depending on location and assembly partners. The pharmacological sensitivity of Kv7.1 channels differs from that of Kv7.2-7.5 and is largely dependent upon the number of β-subunits present in the channel complex. As a result, the development of pharmaceuticals targeting Kv7.1 is problematic. This review discusses the roles and the mechanisms by which different signaling pathways affect Kv7.1 and KCNE channels and could potentially provide different ways of targeting the channel.
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Affiliation(s)
- Emely Thompson
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - David Fedida
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
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Lisewski U, Köhncke C, Schleussner L, Purfürst B, Lee SM, De Silva A, Manville RW, Abbott GW, Roepke TK. Hypochlorhydria reduces mortality in heart failure caused by Kcne2 gene deletion. FASEB J 2020; 34:10699-10719. [PMID: 32584506 DOI: 10.1096/fj.202000013rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 05/20/2020] [Accepted: 06/02/2020] [Indexed: 12/23/2022]
Abstract
Heart failure (HF) is an increasing global health crisis, affecting 40 million people and causing 50% mortality within 5 years of diagnosis. A fuller understanding of the genetic and environmental factors underlying HF, and novel therapeutic approaches to address it, are urgently warranted. Here, we discovered that cardiac-specific germline deletion in mice of potassium channel β subunit-encoding Kcne2 (Kcne2CS-/- ) causes dilated cardiomyopathy and terminal HF (median longevity, 28 weeks). Mice with global Kcne2 deletion (Kcne2Glo-/- ) exhibit multiple HF risk factors, yet, paradoxically survived over twice as long as Kcne2CS-/- mice. Global Kcne2 deletion, which inhibits gastric acid secretion, reduced the relative abundance of species within Bacteroidales, a bacterial order that positively correlates with increased lifetime risk of human cardiovascular disease. Strikingly, the proton-pump inhibitor omeprazole similarly altered the microbiome and delayed terminal HF in Kcne2CS-/- mice, increasing survival 10-fold at 44 weeks. Thus, genetic or pharmacologic induction of hypochlorhydria and decreased gut Bacteroidales species are associated with lifespan extension in a novel HF model.
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Affiliation(s)
| | - Clemens Köhncke
- Experimental and Clinical Research Center, Berlin, Germany.,Department of Cardiology, Campus Virchow - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Bettina Purfürst
- Electron Microscopy Core Facility, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Soo Min Lee
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Angele De Silva
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Berlin, Germany.,Department of Cardiology and Angiology, Campus Mitte, Charité - Universitätsmedizin Berlin, Berlin, Germany
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8
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Hu Z, Liu J, Zhou L, Tian X, Abbott GW. AKT and ERK1/2 activation via remote ischemic preconditioning prevents Kcne2-dependent sudden cardiac death. Physiol Rep 2020; 7:e13957. [PMID: 30737904 PMCID: PMC6368489 DOI: 10.14814/phy2.13957] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 11/26/2018] [Indexed: 02/05/2023] Open
Abstract
Sudden cardiac death (SCD) is the leading global cause of mortality. SCD often arises from cardiac ischemia reperfusion (IR) injury, pathologic sequence variants within ion channel genes, or a combination of the two. Alternative approaches are needed to prevent or ameliorate ventricular arrhythmias linked to SCD. Here, we investigated the efficacy of remote ischemic preconditioning (RIPC) of the limb versus the liver in reducing ventricular arrhythmias in a mouse model of SCD. Mice lacking the Kcne2 gene, which encodes a potassium channel β subunit associated with acquired Long QT syndrome were exposed to IR injury via coronary ligation. This resulted in ventricular arrhythmias in all mice (15/15) and SCD in 5/15 mice during reperfusion. Strikingly, prior RIPC (limb or liver) greatly reduced the incidence and severity of all ventricular arrhythmias and completely prevented SCD. Biochemical and pharmacological analysis demonstrated that RIPC cardioprotection required ERK1/2 and/or AKT phosphorylation. A lack of alteration in GSK‐3β phosphorylation suggested against conventional reperfusion injury salvage kinase (RISK) signaling pathway protection. If replicated in human studies, limb RIPC could represent a noninvasive, nonpharmacological approach to limit dangerous ventricular arrhythmias associated with ischemia and/or channelopathy‐linked SCD.
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Affiliation(s)
- Zhaoyang Hu
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jin Liu
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Leng Zhou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xin Tian
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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9
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Liu W, Wang G, Zhang C, Ding W, Cheng W, Luo Y, Wei C, Liu J. MG53, A Novel Regulator of KChIP2 and I to,f, Plays a Critical Role in Electrophysiological Remodeling in Cardiac Hypertrophy. Circulation 2020; 139:2142-2156. [PMID: 30760025 DOI: 10.1161/circulationaha.118.029413] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND KChIP2 (K+ channel interacting protein) is the auxiliary subunit of the fast transient outward K+ current ( Ito,f) in the heart, and insufficient KChIP2 expression induces Ito,f downregulation and arrhythmogenesis in cardiac hypertrophy. Studies have shown muscle-specific mitsugumin 53 (MG53) has promiscuity of function in the context of normal and diseased heart. This study investigates the possible roles of cardiac MG53 in regulation of KChIP2 expression and Ito,f, and the arrhythmogenic potential in hypertrophy. METHODS MG53 expression is manipulated by genetic ablation of MG53 in mice and adenoviral overexpression or knockdown of MG53 by RNA interference in cultured neonatal rat ventricular myocytes. Cardiomyocyte hypertrophy is produced by phenylephrine stimulation in neonatal rat ventricular myocytes, and pressure overload-induced mouse cardiac hypertrophy is produced by transverse aortic constriction. RESULTS KChIP2 expression and Ito,f density are downregulated in hearts from MG53-knockout mice and MG53-knockdown neonatal rat ventricular myocytes, but upregulated in MG53-overexpressing cells. In phenylephrine-induced cardiomyocyte hypertrophy, MG53 expression is reduced with concomitant downregulation of KChIP2 and Ito,f, which can be reversed by MG53 overexpression, but exaggerated by MG53 knockdown. MG53 knockout enhances Ito,f remodeling and action potential duration prolongation and increases susceptibility to ventricular arrhythmia in mouse cardiac hypertrophy. Mechanistically, MG53 regulates NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activity and subsequently controls KChIP2 transcription. Chromatin immunoprecipitation demonstrates NF-κB protein has interaction with KChIP2 gene. MG53 overexpression decreases, whereas MG53 knockdown increases NF-κB enrichment at the 5' regulatory region of KChIP2 gene. Normalizing NF-κB activity reverses the alterations in KChIP2 in MG53-overexpressing or knockdown cells. Coimmunoprecipitation and Western blotting assays demonstrate MG53 has physical interaction with TAK1 (transforming growth factor-b [TGFb]-activated kinase 1) and IκBα (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha), critical components of the NF-κB pathway. CONCLUSIONS These findings establish MG53 as a novel regulator of KChIP2 and Ito,f by modulating NF-κB activity and reveal its critical role in electrophysiological remodeling in cardiac hypertrophy.
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Affiliation(s)
- Wenjuan Liu
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathophysiology (W.L., G.W., W.C., Y.L., J.L.), School of Medicine, Shenzhen University, China
| | - Gang Wang
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathophysiology (W.L., G.W., W.C., Y.L., J.L.), School of Medicine, Shenzhen University, China
| | - Cuicui Zhang
- Prenatal Diagnosis Center, The Women and Children Hospital of Guangdong Province, Guangzhou, China (C.Z.)
| | - Wenwen Ding
- Department of Basic Medicine, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.)
| | - Wanwen Cheng
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathophysiology (W.L., G.W., W.C., Y.L., J.L.), School of Medicine, Shenzhen University, China
| | - Yizhi Luo
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathophysiology (W.L., G.W., W.C., Y.L., J.L.), School of Medicine, Shenzhen University, China
| | - Chaoliang Wei
- Department of Cell Biology and Medical Genetics (C.W.), School of Medicine, Shenzhen University, China
| | - Jie Liu
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathophysiology (W.L., G.W., W.C., Y.L., J.L.), School of Medicine, Shenzhen University, China
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10
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Zhou L, Köhncke C, Hu Z, Roepke TK, Abbott GW. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury. FASEB J 2019; 33:9762-9774. [PMID: 31162977 DOI: 10.1096/fj.201802519r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The KCNE2 single transmembrane-spanning voltage-gated potassium (Kv) channel β subunit is ubiquitously expressed and essential for normal function of a variety of cell types, often via regulation of the KCNQ1 Kv channel. A polymorphism upstream of KCNE2 is associated with reduced lung function in human populations, but the pulmonary consequences of KCNE2 gene disruption are unknown. Here, germline deletion of mouse Kcne2 reduced pulmonary expression of potassium channel α subunits Kcnq1 and Kcnb1 but did not alter expression of other Kcne genes. Kcne2 colocalized and coimmunoprecipitated with Kcnq1 in mouse lungs, suggesting the formation of pulmonary Kcnq1-Kcne2 potassium channel complexes. Kcne2 deletion reduced blood O2, increased CO2, increased pulmonary apoptosis, and increased inflammatory mediators TNF-α, IL-6, and leukocytes in bronchoalveolar lavage (BAL) fluids. Consistent with increased pulmonary vascular leakage, Kcne2 deletion increased plasma, BAL albumin, and the BAL:plasma albumin concentration ratio. Kcne2-/- mouse lungs exhibited baseline induction of the reperfusion injury salvage kinase pathway but were less able to respond via this pathway to imposed pulmonary ischemia/reperfusion injury (IRI). We conclude that KCNE2 regulates KCNQ1 in the lungs and is required for normal lung function and resistance to pulmonary IRI. Our data support a causal relationship between KCNE2 gene disruption and lung dysfunction.-Zhou, L., Köhncke, C., Hu, Z., Roepke, T. K., Abbott, G. W. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury.
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Affiliation(s)
- Leng Zhou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Clemens Köhncke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Clinic for Cardiology and Angiology, Charité-Berlin University of Medicine Campus Mitte, Berlin, Germany.,Clinic for Internal Medicine and Cardiology Klinikum Niederlausitz, Senftenberg, Germany
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California-Irvine, Irvine, California, USA
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11
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Reduced hybrid/complex N-glycosylation disrupts cardiac electrical signaling and calcium handling in a model of dilated cardiomyopathy. J Mol Cell Cardiol 2019; 132:13-23. [PMID: 31071333 DOI: 10.1016/j.yjmcc.2019.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/12/2019] [Accepted: 05/01/2019] [Indexed: 12/19/2022]
Abstract
Dilated cardiomyopathy (DCM) is the third most common cause of heart failure, with ~70% of DCM cases considered idiopathic. We showed recently, through genetic ablation of the MGAT1 gene, which encodes an essential glycosyltransferase (GlcNAcT1), that prevention of cardiomyocyte hybrid/complex N-glycosylation was sufficient to cause DCM that led to heart failure and early death. Our findings are consistent with increasing evidence suggesting a link between aberrant glycosylation and heart diseases of acquired and congenital etiologies. However, the mechanisms by which changes in glycosylation contribute to disease onset and progression remain largely unknown. Activity and gating of voltage-gated Na+ and K+ channels (Nav and Kv respectively) play pivotal roles in the initiation, shaping and conduction of cardiomyocyte action potentials (APs) and aberrant channel activity was shown to contribute to cardiac disease. We and others showed that glycosylation can impact Nav and Kv function; therefore, here, we investigated the effects of reduced cardiomyocyte hybrid/complex N-glycosylation on channel activity to investigate whether chronic aberrant channel function can contribute to DCM. Ventricular cardiomyocytes from MGAT1 deficient (MGAT1KO) mice display prolonged APs and pacing-induced aberrant early re-activation that can be attributed to, at least in part, a significant reduction in Kv expression and activity that worsens over time suggesting heart disease-related remodeling. MGAT1KO Nav demonstrate no change in expression or maximal conductance but show depolarizing shifts in voltage-dependent gating. Together, the changes in MGAT1KO Nav and Kv function likely contribute to observed anomalous electrocardiograms and Ca2+ handling. These findings provide insight into mechanisms by which altered glycosylation contributes to DCM through changes in Nav and Kv activity that impact conduction, Ca2+ handling and contraction. The MGAT1KO can also serve as a useful model to study the effects of aberrant electrical signaling on cardiac function and the remodeling events that can occur with heart disease progression.
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12
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Calloe K. Doctoral Dissertation: The transient outward potassium current in healthy and diseased hearts. Acta Physiol (Oxf) 2019; 225 Suppl 717:e13225. [PMID: 30628199 DOI: 10.1111/apha.13225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Kirstine Calloe
- Section for Anatomy; Biochemistry and Physiology; Department for Veterinary and Animal Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg C Denmark
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13
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David JP, Lisewski U, Crump SM, Jepps TA, Bocksteins E, Wilck N, Lossie J, Roepke TK, Schmitt N, Abbott GW. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular K V currents and predisposes to ventricular arrhythmia. FASEB J 2018; 33:2537-2552. [PMID: 30289750 DOI: 10.1096/fj.201800502r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
KCNE5 is an X-linked gene encoding KCNE5, an ancillary subunit to voltage-gated potassium (KV) channels. Human KCNE5 mutations are associated with atrial fibrillation (AF)- and Brugada syndrome (BrS)-induced cardiac arrhythmias that can arise from increased potassium current in cardiomyocytes. Seeking to establish underlying molecular mechanisms, we created and studied Kcne5 knockout ( Kcne5-/0) mice. Intracardiac ECG revealed that Kcne5 deletion caused ventricular premature beats, increased susceptibility to induction of polymorphic ventricular tachycardia (60 vs. 24% in Kcne5+/0 mice), and 10% shorter ventricular refractory period. Kcne5 deletion increased mean ventricular myocyte KV current density in the apex and also in the subpopulation of septal myocytes that lack fast transient outward current ( Ito,f). The current increases arose from an apex-specific increase in slow transient outward current-1 ( IKslow,1) (conducted by KV1.5) and Ito,f (conducted by KV4) and an increase in IKslow,2 (conducted by KV2.1) in both apex and septum. Kcne5 protein localized to the intercalated discs in ventricular myocytes, where KV2.1 was also detected in both Kcne5-/0 and Kcne5+/0 mice. In HL-1 cardiac cells and human embryonic kidney cells, KCNE5 and KV2.1 colocalized at the cell surface, but predominantly in intracellular vesicles, suggesting that Kcne5 deletion increases IK,slow2 by reducing KV2.1 intracellular sequestration. The human AF-associated mutation KCNE5-L65F negative shifted the voltage dependence of KV2.1-KCNE5 channels, increasing their maximum current density >2-fold, whereas BrS-associated KCNE5 mutations produced more subtle negative shifts in KV2.1 voltage dependence. The findings represent the first reported native role for Kcne5 and the first demonstrated Kcne regulation of KV2.1 in mouse heart. Increased KV current is a manifestation of KCNE5 disruption that is most likely common to both mouse and human hearts, providing a plausible mechanistic basis for human KCNE5-linked AF and BrS.-David, J.-P., Lisewski, U., Crump, S. M., Jepps, T. A., Bocksteins, E., Wilck, N., Lossie, J., Roepke, T. K., Schmitt, N., Abbott, G. W. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular KV currents and predisposes to ventricular arrhythmia.
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Affiliation(s)
- Jens-Peter David
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrike Lisewski
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Shawn M Crump
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
| | - Thomas A Jepps
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elke Bocksteins
- Laboratory for Molecular Biophysics, Physiology, and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Nicola Wilck
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Janine Lossie
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Torsten K Roepke
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
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14
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Sherman SB, Sarsour N, Salehi M, Schroering A, Mell B, Joe B, Hill JW. Prenatal androgen exposure causes hypertension and gut microbiota dysbiosis. Gut Microbes 2018; 9:400-421. [PMID: 29469650 PMCID: PMC6219642 DOI: 10.1080/19490976.2018.1441664] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/24/2017] [Accepted: 02/08/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Conditions of excess androgen in women, such as polycystic ovary syndrome (PCOS), often exhibit intergenerational transmission. One way in which the risk for PCOS may be increased in daughters of affected women is through exposure to elevated androgens in utero. Hyperandrogenemic conditions have serious health consequences, including increased risk for hypertension and cardiovascular disease. Recently, gut dysbiosis has been found to induce hypertension in rats, such that blood pressure can be normalized through fecal microbial transplant. Therefore, we hypothesized that the hypertension seen in PCOS has early origins in gut dysbiosis caused by in utero exposure to excess androgen. We investigated this hypothesis with a model of prenatal androgen (PNA) exposure and maternal hyperandrogenemia by single-injection of testosterone cypionate or sesame oil vehicle (VEH) to pregnant dams in late gestation. We then completed a gut microbiota and cardiometabolic profile of the adult female offspring. RESULTS The metabolic assessment revealed that adult PNA rats had increased body weight and increased mRNA expression of adipokines: adipocyte binding protein 2, adiponectin, and leptin in inguinal white adipose tissue. Radiotelemetry analysis revealed hypertension with decreased heart rate in PNA animals. The fecal microbiota profile of PNA animals contained higher relative abundance of bacteria associated with steroid hormone synthesis, Nocardiaceae and Clostridiaceae, and lower abundance of Akkermansia, Bacteroides, Lactobacillus, Clostridium. The PNA animals also had an increased relative abundance of bacteria associated with biosynthesis and elongation of unsaturated short chain fatty acids (SCFAs). CONCLUSIONS We found that prenatal exposure to excess androgen negatively impacted cardiovascular function by increasing systolic and diastolic blood pressure and decreasing heart rate. Prenatal androgen was also associated with gut microbial dysbiosis and altered abundance of bacteria involved in metabolite production of short chain fatty acids. These results suggest that early-life exposure to hyperandrogenemia in daughters of women with PCOS may lead to long-term alterations in gut microbiota and cardiometabolic function.
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Affiliation(s)
- Shermel B. Sherman
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Nadeen Sarsour
- Department of Biological Sciences, University of Toledo, Toledo, OH
| | - Marziyeh Salehi
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Allen Schroering
- Department of Neurosciences and Neurological Disorders, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Blair Mell
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
- Center for Hypertension and Personalized Medicine, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Bina Joe
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
- Center for Hypertension and Personalized Medicine, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Jennifer W. Hill
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
- Center for Diabetes and Endocrine Research, The University of Toledo College of Medicine and Life Sciences, Toledo, OH
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15
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Giudicessi JR, Wilde AAM, Ackerman MJ. The genetic architecture of long QT syndrome: A critical reappraisal. Trends Cardiovasc Med 2018; 28:453-464. [PMID: 29661707 DOI: 10.1016/j.tcm.2018.03.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 12/19/2022]
Abstract
Collectively, the completion of the Human Genome Project and subsequent development of high-throughput next-generation sequencing methodologies have revolutionized genomic research. However, the rapid sequencing and analysis of thousands upon thousands of human exomes and genomes has taught us that most genes, including those known to cause heritable cardiovascular disorders such as long QT syndrome, harbor an unexpected background rate of rare, and presumably innocuous, non-synonymous genetic variation. In this Review, we aim to reappraise the genetic architecture underlying both the acquired and congenital forms of long QT syndrome by examining how the clinical phenotype associated with and background genetic variation in long QT syndrome-susceptibility genes impacts the clinical validity of existing gene-disease associations and the variant classification and reporting strategies that serve as the foundation for diagnostic long QT syndrome genetic testing.
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Affiliation(s)
- John R Giudicessi
- Department of Cardiovascular Medicine (Cardiovascular Diseases Fellowship and Clinician-Investigator Training Programs), Mayo Clinic, Rochester, MN, United States
| | - Arthur A M Wilde
- Department of Medicine (Division of Cardiology), Columbia University Irving Medical Center, New York, NY, United States; Department of Clinical & Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, United States.
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16
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Abstract
This study examines the interaction between hERG and Kv4.3. The functional interaction between hERG and Kv4.3, expressed in a heterologous cell line, was studied using patch clamp techniques, western blot, immunofluorescence, and co-immunoprecipitation. Co-expression of Kv4.3 with hERG increased hERG current density (tail current after a step to +10 mV: 26 ± 3 versus 56 ± 7 pA/pF, p < 0.01). Kv4.3 co-expression also increased the protein expression and promoted the membrane localization of hERG. Western blot showed Kv4.3 increased hERG expression by Hsp70. hERG and Kv4.3 co-localized and co-immunoprecipitated in cultured 293 T cells, indicating physical interactions between hERG and Kv4.3 proteins in vitro. In addition, Hsp70 interacted with hERG and Kv4.3 respectively, and formed complexes with hERG and Kv4.3. The α subunit of Ito Kv4.3 can interact with and modify the localization of the α subunit of IKr hERG, thus providing potentially novel insights into the molecular mechanism of the malignant ventricular arrhythmia in heart failure.
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17
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Abbott GW. β Subunits Control the Effects of Human Kv4.3 Potassium Channel Phosphorylation. Front Physiol 2017; 8:646. [PMID: 28919864 PMCID: PMC5585193 DOI: 10.3389/fphys.2017.00646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/16/2017] [Indexed: 11/17/2022] Open
Abstract
The transient outward K+ current, Ito, activates early in the cardiac myocyte action potential, to begin repolarization. Human Ito is generated primarily by two Kv4.3 potassium channel α subunit splice variants (Kv4.3L and Kv4.3S) that diverge only by a C-terminal, membrane-proximal, 19-residue stretch unique to Kv4.3L. Protein kinase C (PKC) phosphorylation of threonine 504 within the Kv4.3L-specific 19-residues mediates α-adrenergic inhibition of Ito in human heart. Kv4.3 is regulated in human heart by various β subunits, including cytosolic KChIP2b and transmembrane KCNEs, yet their impact on the functional effects of human Kv4.3 phosphorylation has not been reported. Here, this gap in knowledge was addressed using human Kv4.3 splice variants, T504 mutants, and human β subunits. Subunits were co-expressed in Xenopus laevis oocytes and analyzed by two-electrode voltage-clamp, using phorbol 12-myristate 13-acetate (PMA) to stimulate PKC. Unexpectedly, KChIP2b removed the inhibitory effect of PKC on Kv4.3L (but not Kv4.3L threonine phosphorylation by PKC per-se), while co-expression with KCNE2, but not KCNE4, restored PKC-dependent inhibition of Kv4.3L-KChIP2b to quantitatively resemble previously reported effects of α-adrenergic modulation of human ventricular Ito. In addition, PKC accelerated recovery from inactivation of Kv4.3L-KChIP2b channels and, interestingly, of both Kv4.3L and Kv4.3S alone. Thus, β subunits regulate the response of human Kv4.3 to PKC phosphorylation and provide a potential mechanism for modifying the response of Ito to α-adrenergic regulation in vivo.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, IrvineIrvine, CA, United States
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18
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Liu W, Deng J, Ding W, Wang G, Shen Y, Zheng J, Zhang X, Luo Y, Lv C, Wang Y, Chen L, Yan D, Boudreau RL, Song LS, Liu J. Decreased KCNE2 Expression Participates in the Development of Cardiac Hypertrophy by Regulation of Calcineurin-NFAT (Nuclear Factor of Activated T Cells) and Mitogen-Activated Protein Kinase Pathways. Circ Heart Fail 2017; 10:CIRCHEARTFAILURE.117.003960. [PMID: 28611128 DOI: 10.1161/circheartfailure.117.003960] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 05/15/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND KCNE2 is a promiscuous auxiliary subunit of voltage-gated cation channels. A recent work demonstrated that KCNE2 regulates L-type Ca2+ channels. Given the important roles of altered Ca2+ signaling in structural and functional remodeling in diseased hearts, this study investigated whether KCNE2 participates in the development of pathological hypertrophy. METHODS AND RESULTS We found that cardiac KCNE2 expression was significantly decreased in phenylephrine-induced cardiomyocyte hypertrophy in neonatal rat ventricular myocytes and in transverse aortic constriction-induced cardiac hypertrophy in mice, as well as in dilated cardiomyopathy in human. Knockdown of KCNE2 in neonatal rat ventricular myocytes reproduced hypertrophy by increasing the expression of ANP (atrial natriuretic peptide) and β-MHC (β-myosin heavy chain), and cell surface area, whereas overexpression of KCNE2 attenuated phenylephrine-induced cardiomyocyte hypertrophy. Knockdown of KCNE2 increased intracellular Ca2+ transient, calcineurin activity, and nuclear NFAT (nuclear factor of activated T cells) protein levels, and pretreatment with inhibitor of L-type Ca2+ channel (nifedipine) or calcineurin (FK506) attenuated the activation of calcineurin-NFAT pathway and cardiomyocyte hypertrophy. Meanwhile, the phosphorylation levels of p38, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase were increased, and inhibiting the 3 cascades of mitogen-activated protein kinase reduced cardiomyocyte hypertrophy induced by KCNE2 knockdown. Overexpression of KCNE2 in heart by ultrasound-microbubble-mediated gene transfer suppressed the development of hypertrophy and activation of calcineurin-NFAT and mitogen-activated protein kinase pathways in transverse aortic constriction mice. CONCLUSIONS This study demonstrates that cardiac KCNE2 expression is decreased and contributes to the development of hypertrophy via activation of calcineurin-NFAT and mitogen-activated protein kinase pathways. Targeting KCNE2 is a potential therapeutic strategy for the treatment of hypertrophy.
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Affiliation(s)
- Wenjuan Liu
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Jianxin Deng
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Wenwen Ding
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Gang Wang
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Yuanyuan Shen
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Junmeng Zheng
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Xiaoming Zhang
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Yizhi Luo
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Chifei Lv
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Yonghui Wang
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Liqing Chen
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Dewen Yan
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Ryan L Boudreau
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Long-Sheng Song
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.)
| | - Jie Liu
- From the Department of Pathophysiology, School of Medicine (W.L., G.W., Y.L., C.L., Y.W., L.C., J.L.); Department of Endocrinology, The First Affiliated Hospital of Shenzhen University (J.D., D.Y.), Center for Diabetes, Obesity and Metabolism (J.D., D.Y.), and Department of Biomedical Engineering, School of Medicine (Y.S.), Shenzhen University, China; Department of Pathology, School of Medicine, Jingchu University of Technology, Jingmen, China (W.D.); Zhongshan People's Hospital, China (J.Z.); and Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City (X.Z., R.L.B., L.-S.S.).
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Harmer SC, Tinker A. The impact of recent advances in genetics in understanding disease mechanisms underlying the long QT syndromes. Biol Chem 2017; 397:679-93. [PMID: 26910742 DOI: 10.1515/hsz-2015-0306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/18/2016] [Indexed: 11/15/2022]
Abstract
Long QT syndrome refers to a characteristic abnormality of the electrocardiogram and it is associated with a form of ventricular tachycardia known as torsade-de-pointes and sudden arrhythmic death. It can occur as part of a hereditary syndrome or can be acquired usually because of drug administration. Here we review recent genetic, molecular and cellular discoveries and outline how they have furthered our understanding of this disease. Specifically we focus on compound mutations, genome wide association studies of QT interval, modifier genes and the therapeutic implications of this recent work.
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20
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Andrews CM, Srinivasan NT, Rosmini S, Bulluck H, Orini M, Jenkins S, Pantazis A, McKenna WJ, Moon JC, Lambiase PD, Rudy Y. Electrical and Structural Substrate of Arrhythmogenic Right Ventricular Cardiomyopathy Determined Using Noninvasive Electrocardiographic Imaging and Late Gadolinium Magnetic Resonance Imaging. Circ Arrhythm Electrophysiol 2017; 10:e005105. [PMID: 28705875 PMCID: PMC5533087 DOI: 10.1161/circep.116.005105] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 06/05/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a significant cause of sudden cardiac death in the young. Improved noninvasive assessment of ARVC and better understanding of the disease substrate are important for improving patient outcomes. METHODS AND RESULTS We studied 20 genotyped ARVC patients with a broad spectrum of disease using electrocardiographic imaging (a method for noninvasive cardiac electrophysiology mapping) and advanced late gadolinium enhancement cardiac magnetic resonance scar imaging. Compared with 20 healthy controls, ARVC patients had longer ventricular activation duration (median, 52 versus 42 ms; P=0.007) and prolonged mean epicardial activation-recovery intervals (a surrogate for local action potential duration; median, 275 versus 241 ms; P=0.014). In these patients, we observed abnormal and varied epicardial activation breakthrough locations and regions of nonuniform conduction and fractionated electrograms. Nonuniform conduction and fractionated electrograms were present in the early concealed phase of ARVC. Electrophysiological abnormalities colocalized with late gadolinium enhancement scar, indicating a relationship with structural disease. Premature ventricular contractions were common in ARVC patients with variable initiation sites in both ventricles. Premature ventricular contraction rate increased with exercise, and within anatomic segments, it correlated with prolonged repolarization, electric markers of scar, and late gadolinium enhancement (all P<0.001). CONCLUSIONS Electrocardiographic imaging reveals electrophysiological substrate properties that differ in ARVC patients compared with healthy controls. A novel mechanistic finding is the presence of repolarization abnormalities in regions where ventricular ectopy originates. The results suggest a potential role for electrocardiographic imaging and late gadolinium enhancement in early diagnosis and noninvasive follow-up of ARVC patients.
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Affiliation(s)
- Christopher M Andrews
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.).
| | - Neil T Srinivasan
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Stefania Rosmini
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Heerajnarain Bulluck
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Michele Orini
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Sharon Jenkins
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Antonis Pantazis
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - William J McKenna
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - James C Moon
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Pier D Lambiase
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.)
| | - Yoram Rudy
- From the Department of Biomedical Engineering (C.M.A., Y.R.) and Cardiac Bioelectricity and Arrhythmia Center (C.M.A., Y.R.), Washington University, St. Louis, MO; Department of Medicine, Cardiovascular Division, Washington University in St. Louis, MO (Y.R.); Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom (N.T.S., M.O., S.J., A.P., W.J.M., P.D.L.); and Institute of Cardiovascular Science, University College London, United Kingdom (N.T.S., S.R., H.B., M.O., S.J., A.P., W.J.M., J.C.M., P.D.L.).
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Lee SM, Baik J, Nguyen D, Nguyen V, Liu S, Hu Z, Abbott GW. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus. FASEB J 2017; 31:2674-2685. [PMID: 28280005 DOI: 10.1096/fj.201601347] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/21/2017] [Indexed: 02/05/2023]
Abstract
Type 2 diabetes mellitus (T2DM) represents a rapidly increasing threat to global public health. T2DM arises largely from obesity, poor diet, and lack of exercise, but it also involves genetic predisposition. Here we report that the KCNE2 potassium channel transmembrane regulatory subunit is expressed in human and mouse pancreatic β cells. Kcne2 deletion in mice impaired glucose tolerance as early as 5 wk of age in pups fed a Western diet, ultimately causing diabetes. In adult mice fed normal chow, skeletal muscle expression of insulin receptor β and insulin receptor substrate 1 were down-regulated 2-fold by Kcne2 deletion, characteristic of T2DM. Kcne2 deletion also caused extensive pancreatic transcriptome changes consistent with facets of T2DM, including endoplasmic reticulum stress, inflammation, and hyperproliferation. Kcne2 deletion impaired β-cell insulin secretion in vitro up to 8-fold and diminished β-cell peak outward K+ current at positive membrane potentials, but also left-shifted its voltage dependence and slowed inactivation. Interestingly, we also observed an aging-dependent reduction in β-cell outward currents in both Kcne2+/+ and Kcne2-/- mice. Our results demonstrate that KCNE2 is required for normal β-cell electrical activity and insulin secretion, and that Kcne2 deletion causes T2DM. KCNE2 may regulate multiple K+ channels in β cells, including the T2DM-linked KCNQ1 potassium channel α subunit.-Lee, S. M., Baik, J., Nguyen, D., Nguyen, V., Liu, S., Hu, Z., Abbott, G. W. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus.
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Affiliation(s)
- Soo Min Lee
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Jasmine Baik
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Dara Nguyen
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Victoria Nguyen
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Shiwei Liu
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA;
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22
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Kukreja RC. Myriad roles of voltage-activated potassium channel subunit Kvβ1.1 in the heart. Am J Physiol Heart Circ Physiol 2017; 312:H546-H548. [PMID: 28130332 DOI: 10.1152/ajpheart.00005.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Rakesh C Kukreja
- Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia
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23
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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24
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Regulation of human cardiac potassium channels by full-length KCNE3 and KCNE4. Sci Rep 2016; 6:38412. [PMID: 27922120 PMCID: PMC5138848 DOI: 10.1038/srep38412] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/09/2016] [Indexed: 12/23/2022] Open
Abstract
Voltage-gated potassium (Kv) channels comprise pore-forming α subunits and a multiplicity of regulatory proteins, including the cardiac-expressed and cardiac arrhythmia-linked transmembrane KCNE subunits. After recently uncovering novel, N-terminally extended (L) KCNE3 and KCNE4 isoforms and detecting their transcripts in human atrium, reported here are their functional effects on human cardiac Kv channel α subunits expressed in Xenopus laevis oocytes. As previously reported for short isoforms KCNE3S and KCNE4S, KCNE3L inhibited hERG; KCNE4L inhibited Kv1.1; neither form regulated the HCN1 pacemaker channel. Unlike KCNE4S, KCNE4L was a potent inhibitor of Kv4.2 and Kv4.3; co-expression of cytosolic β subunit KChIP2, which regulates Kv4 channels in cardiac myocytes, partially relieved Kv4.3 but not Kv4.2 inhibition. Inhibition of Kv4.2 and Kv4.3 by KCNE3L was weaker, and its inhibition of Kv4.2 abolished by KChIP2. KCNE3L and KCNE4L also exhibited subunit-specific effects on Kv4 channel complex inactivation kinetics, voltage dependence and recovery. Further supporting the potential physiological significance of the robust functional effects of KCNE4L on Kv4 channels, KCNE4L protein was detected in human atrium, where it co-localized with Kv4.3. The findings establish functional effects of novel human cardiac-expressed KCNE isoforms and further contribute to our understanding of the potential mechanisms influencing cardiomyocyte repolarization.
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25
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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26
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Abbott GW, Jepps TA. Kcne4 Deletion Sex-Dependently Alters Vascular Reactivity. J Vasc Res 2016; 53:138-148. [PMID: 27710966 DOI: 10.1159/000449060] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 08/10/2016] [Indexed: 01/06/2023] Open
Abstract
Voltage-gated potassium (Kv) channels formed by Kv7 (KCNQ) α-subunits are recognized as crucial for vascular smooth muscle function, in addition to their established roles in the heart (Kv7.1) and the brain (Kv7.2-5). In vivo, Kv7 α-subunits are often regulated by KCNE subfamily ancillary (β) subunits. We investigated the effects of targeted germline Kcne4 deletion on mesenteric artery reactivity in adult male and female mice. Kcne4 deletion increased mesenteric artery contractility in response to α-adrenoceptor agonist methoxamine, and decreased responses to Kv7.2-7.5 channel activator ML213, in male but not female mice. In contrast, Kcne4 deletion markedly decreased vasorelaxation in response to isoprenaline in both male and female mice. Kcne4 expression was 2-fold lower in the female versus the male mouse mesenteric artery, and Kcne4 deletion elicited only moderate changes of other Kcne transcripts, with no striking sex-specific differences. However, Kv7.4 protein expression in females was twice that in males, and was reduced in both sexes by Kcne4 deletion. Our findings confirm a crucial role for KCNE4 in regulation of Kv7 channel activity to modulate vascular tone, and provide the first known molecular mechanism for sex-specificity of this modulation that has important implications for vascular reactivity and may underlie sex-specific susceptibility to cardiovascular diseases.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Departments of Pharmacology and Physiology and Biophysics, School of Medicine, University of California, Irvine, Calif., USA
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27
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Abbott GW. Novel exon 1 protein-coding regions N-terminally extend human KCNE3 and KCNE4. FASEB J 2016; 30:2959-69. [PMID: 27162025 DOI: 10.1096/fj.201600467r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 04/26/2016] [Indexed: 01/02/2023]
Abstract
The 5 human (h)KCNE β subunits each regulate various cation channels and are linked to inherited cardiac arrhythmias. Reported here are previously undiscovered protein-coding regions in exon 1 of hKCNE3 and hKCNE4 that extend their encoded extracellular domains by 44 and 51 residues, which yields full-length proteins of 147 and 221 residues, respectively. Full-length hKCNE3 and hKCNE4 transcript and protein are expressed in multiple human tissues; for hKCNE4, only the longer protein isoform is detectable. Two-electrode voltage-clamp electrophysiology revealed that, when coexpressed in Xenopus laevis oocytes with various potassium channels, the newly discovered segment preserved conversion of KCNQ1 by hKCNE3 to a constitutively open channel, but prevented its inhibition of Kv4.2 and KCNQ4. hKCNE4 slowing of Kv4.2 inactivation and positive-shifted steady-state inactivation were also preserved in the longer form. In contrast, full-length hKCNE4 inhibition of KCNQ1 was limited to 40% at +40 mV vs. 80% inhibition by the shorter form, and augmentation of KCNQ4 activity by hKCNE4 was entirely abolished by the additional segment. Among the genome databases analyzed, the longer KCNE3 is confined to primates; full-length KCNE4 is widespread in vertebrates but is notably absent from Mus musculus Findings highlight unexpected KCNE gene diversity, raise the possibility of dynamic regulation of KCNE partner modulation via splice variation, and suggest that the longer hKCNE3 and hKCNE4 proteins should be adopted in future mechanistic and genetic screening studies.-Abbott, G. W. Novel exon 1 protein-coding regions N-terminally extend human KCNE3 and KCNE4.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
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28
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Kcne2 deletion causes early-onset nonalcoholic fatty liver disease via iron deficiency anemia. Sci Rep 2016; 6:23118. [PMID: 26984260 PMCID: PMC4794722 DOI: 10.1038/srep23118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/26/2016] [Indexed: 02/05/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is an increasing health problem worldwide, with genetic, epigenetic, and environmental components. Here, we describe the first example of NAFLD caused by genetic disruption of a mammalian potassium channel subunit. Mice with germline deletion of the KCNE2 potassium channel β subunit exhibited NAFLD as early as postnatal day 7. Using mouse genetics, histology, liver damage assays and transcriptomics we discovered that iron deficiency arising from KCNE2-dependent achlorhydria is a major factor in early-onset NAFLD in Kcne2(─/─) mice, while two other KCNE2-dependent defects did not initiate NAFLD. The findings uncover a novel genetic basis for NAFLD and an unexpected potential factor in human KCNE2-associated cardiovascular pathologies, including atherosclerosis.
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29
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Lisewski U, Koehncke C, Wilck N, Buschmeyer B, Pieske B, Roepke TK. Increased aldosterone-dependent Kv1.5 recycling predisposes to pacing-induced atrial fibrillation in Kcne3-/- mice. FASEB J 2016; 30:2476-89. [PMID: 26985008 DOI: 10.1096/fj.201600317r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/02/2016] [Indexed: 01/11/2023]
Abstract
Hyperaldosteronism is associated with an increased prevalence of atrial fibrillation (AF). Mutations in KCNE3 have been associated with AF, and Kcne3(-/-) mice exhibit hyperaldosteronism. In this study, we used recently developed Kcne3(-/-) mice to study atrial electrophysiology with respect to development of aldosterone-dependent AF. In invasive electrophysiology studies, Kcne3(-/-) mice displayed a reduced atrial effective refractory period (AERP) and inducible episodes of paroxysmal AF. The cellular arrhythmogenic correlate for AF predisposition was a significant increase in atrial Kv currents generated by the micromolar 4-aminopyridine-sensitive Kv current encoded by Kv1.5. Electrophysiological alterations in Kcne3(-/-) mice were aldosterone dependent and were associated with increased Rab4, -5, and -9-dependent recycling of Kv1.5 channels to the Z-disc/T-tubulus region and lateral membrane via activation of the Akt/AS160 pathway. Treatment with spironolactone inhibited Akt/AS160 phosphorylation, reduced Rab-dependent Kv1.5 recycling, normalized AERP and atrial Kv currents to the wild-type level, and reduced arrhythmia induction in Kcne3(-/-) mice. Kcne3 deletion in mice predisposes to AF by a heretofore unrecognized mechanism-namely, increased aldosterone-dependent Kv1.5 recycling via Rab GTPases. The findings uncover detailed molecular mechanisms underpinning a channelopathy-linked form of AF and emphasize the inevitability of considering extracardiac mechanisms in genetic arrhythmia syndromes.-Lisewski, U., Koehncke, C., Wilck, N., Buschmeyer, B., Pieske, B., Roepke, T. K. Increased aldosterone-dependent Kv1.5 recycling predisposes to pacing-induced atrial fibrillation in Kcne3(-/-) mice.
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Affiliation(s)
| | - Clemens Koehncke
- Experimental and Clinical Research Center, Berlin, Germany; Department of Cardiology, Campus Virchow, Universitätsmedizin Berlin, Berlin, Germany; and
| | - Nicola Wilck
- Experimental and Clinical Research Center, Berlin, Germany
| | | | - Burkert Pieske
- Department of Cardiology, Campus Virchow, Universitätsmedizin Berlin, Berlin, Germany; and
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Berlin, Germany; Department of Cardiology and Angiology, Campus Mitte, Charité, Universitätsmedizin Berlin, Berlin, Germany
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30
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Dubó S, Gallegos D, Cabrera L, Sobrevia L, Zúñiga L, González M. Cardiovascular Action of Insulin in Health and Disease: Endothelial L-Arginine Transport and Cardiac Voltage-Dependent Potassium Channels. Front Physiol 2016; 7:74. [PMID: 27014078 PMCID: PMC4791397 DOI: 10.3389/fphys.2016.00074] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/15/2016] [Indexed: 12/19/2022] Open
Abstract
Impairment of insulin signaling on diabetes mellitus has been related to cardiovascular dysfunction, heart failure, and sudden death. In human endothelium, cationic amino acid transporter 1 (hCAT-1) is related to the synthesis of nitric oxide (NO) and insulin has a vascular effect in endothelial cells through a signaling pathway that involves increases in hCAT-1 expression and L-arginine transport. This mechanism is disrupted in diabetes, a phenomenon potentiated by excessive accumulation of reactive oxygen species (ROS), which contribute to lower availability of NO and endothelial dysfunction. On the other hand, electrical remodeling in cardiomyocytes is considered a key factor in heart failure progression associated to diabetes mellitus. This generates a challenge to understand the specific role of insulin and the pathways involved in cardiac function. Studies on isolated mammalian cardiomyocytes have shown prolongated action potential in ventricular repolarization phase that produces a long QT interval, which is well explained by attenuation in the repolarizing potassium currents in cardiac ventricles. Impaired insulin signaling causes specific changes in these currents, such a decrease amplitude of the transient outward K(+) (Ito) and the ultra-rapid delayed rectifier (IKur) currents where, together, a reduction of mRNA and protein expression levels of α-subunits (Ito, fast; Kv 4.2 and IKs; Kv 1.5) or β-subunits (KChIP2 and MiRP) of K(+) channels involved in these currents in a MAPK mediated pathway process have been described. These results support the hypothesis that lack of insulin signaling can produce an abnormal repolarization in cardiomyocytes. Furthermore, the arrhythmogenic potential due to reduced Ito current can contribute to an increase in the incidence of sudden death in heart failure. This review aims to show, based on pathophysiological models, the regulatory function that would have insulin in vascular system and in cardiac electrophysiology.
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Affiliation(s)
- Sebastián Dubó
- Department of Kinesiology, Faculty of Medicine, Universidad de Concepción Concepción, Chile
| | - David Gallegos
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de Concepción Concepción, Chile
| | - Lissette Cabrera
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de ConcepciónConcepción, Chile; Department of Morphophysiology, Faculty of Medicine, Universidad Diego PortalesSantiago, Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynecology, Faculty of Medicine, School of Medicine, Pontificia Universidad Católica de ChileSantiago, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de SevillaSeville, Spain; Faculty of Medicine and Biomedical Sciences, University of Queensland Centre for Clinical Research (UQCCR), University of QueenslandHerston, QLD, Queensland, Australia
| | - Leandro Zúñiga
- Centro de Investigaciones Médicas, Escuela de Medicina, Universidad de Talca Talca, Chile
| | - Marcelo González
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de ConcepciónConcepción, Chile; Group of Research and Innovation in Vascular Health (GRIVAS-Health)Chillán, Chile
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Hu Z, Crump SM, Zhang P, Abbott GW. Kcne2 deletion attenuates acute post-ischaemia/reperfusion myocardial infarction. Cardiovasc Res 2016; 110:227-37. [PMID: 26952045 DOI: 10.1093/cvr/cvw048] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 02/28/2016] [Indexed: 02/05/2023] Open
Abstract
AIMS Most cardiac arrhythmia-associated genes encode ion channel subunits and regulatory proteins that are also expressed outside the heart, suggesting that diseases linked to their disruption may be multifactorial. KCNE2 is a ubiquitously expressed potassium channel β subunit associated with cardiac arrhythmia, atherosclerosis, and myocardial infarction (MI) in human populations. Here, we tested the hypothesis that Kcne2 disruption in mice would influence the acute outcome of experimentally induced MI. METHODS AND RESULTS One-year-old male Kcne2⁺/⁺ and Kcne2⁻/⁻ mice were subjected to cardiac ischaemia/reperfusion injury (IRI) by left anterior descending coronary artery ligation. After reperfusion (3 h), infarct size and markers of tissue damage were quantified. Unexpectedly, post-reperfusion, Kcne2⁻/⁻ mice exhibited 40% lower infarct size, decreased myocardial apoptosis and damage, and more than two-fold lower serum levels of damage markers, lactate dehydrogenase and creatine kinase, than Kcne2⁺/⁺ mice. Kcne2 deletion, despite increasing normalized heart weight and prolonging baseline QTc by 70%, helped preserve post-infarct cardiac function (quantified by a Millar catheter), with parameters including left ventricular maximum pressure, max dP/dt (P < 0.01), contractility index, and pressure/time index (P < 0.05) all greater in Kcne2⁻/⁻ compared with Kcne2⁺/⁺ mice. Western blotting indicated two-fold-increased glycogen synthase kinase 3β (GSK-3β) phosphorylation (inactivation) before and after IRI (P < 0.05) in Kcne2⁻/⁻ mice compared with Kcne2⁺/⁺ mice. GSK-3β inhibition by SB216763 mimicked in Kcne2⁺/⁺ mice the cardioprotective effects of Kcne2 deletion, but did not further enhance them in Kcne2⁻/⁻mice, suggesting that GSK-3β inactivation was a primary cardioprotective mechanism arising from Kcne2 deletion. CONCLUSIONS Kcne2 deletion preconditions the heart, attenuating the acute tissue damage caused by an imposed IRI. The findings contribute further evidence that genetic disruption of arrhythmia-associated ion channel genes has cardiac ramifications beyond abnormal electrical activity.
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Affiliation(s)
- Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Shawn M Crump
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Ping Zhang
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
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Liu WJ, Deng JX, Wang G, Gao KP, Lin ZX, Liu SY, Wang YH, Liu J. Manipulation of KCNE2 expression modulates action potential duration and Ito and IK in rat and mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 2015; 309:H1288-302. [PMID: 26297229 DOI: 10.1152/ajpheart.00757.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 08/19/2015] [Indexed: 11/22/2022]
Abstract
In heterologous expression systems, KCNE2 has been demonstrated to interact with multiple α-subunits of voltage-dependent cation channels and modulate their functions. However, the physiological and pathological roles of KCNE2 in cardiomyocytes are poorly understood. The present study aimed to investigate the effects of bidirectional modulation of KCNE2 expression on action potential (AP) duration (APD) and voltage-dependent K+ channels in cardiomyocytes. Adenoviral gene delivery and RNA interference were used to either increase or decrease KCNE2 expression in cultured neonatal and adult rat or neonatal mouse ventricular myocytes. Knockdown of KCNE2 prolonged APD in both neonatal and adult myocytes, whereas overexpression of KCNE2 shortened APD in neonatal but not adult myocytes. Consistent with the alterations in APD, KCNE2 knockdown decreased transient outward K+ current ( Ito) densities in neonatal and adult myocytes, whereas KCNE2 overexpression increased Ito densities in neonatal but not adult myocytes. Furthermore, KCNE2 knockdown accelerated the rates of Ito activation and inactivation, whereas KCNE2 overexpression slowed Ito gating kinetics in neonatal but not adult myocytes. Delayed rectifier K+ current densities were remarkably affected by manipulation of KCNE2 expression in mouse but not rat cardiomyocytes. Simulation of the AP of a rat ventricular myocyte with a mathematical model showed that alterations in Ito densities and gating properties can result in similar APD alterations in KCNE2 overexpression and knockdown cells. In conclusion, endogenous KCNE2 in cardiomyocytes is important in maintaining cardiac electrical stability mainly by regulating Ito and APD. Perturbation of KCNE2 expression may predispose the heart to ventricular arrhythmia by prolonging APD.
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Affiliation(s)
- Wen-juan Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Jian-xin Deng
- Department of Endocrinology, The First Affiliated Hospital of Shenzhen University, Shenzhen No. 2 People's Hospital, Shenzhen, China
| | - Gang Wang
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Kai-ping Gao
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Ze-xun Lin
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Shuai-ye Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Yong-hui Wang
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Jie Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
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Crump SM, Hu Z, Kant R, Levy DI, Goldstein SAN, Abbott GW. Kcne4 deletion sex- and age-specifically impairs cardiac repolarization in mice. FASEB J 2015; 30:360-9. [PMID: 26399785 DOI: 10.1096/fj.15-278754] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/08/2015] [Indexed: 02/05/2023]
Abstract
Myocardial repolarization capacity varies with sex, age, and pathology; the molecular basis for this variation is incompletely understood. Here, we show that the transcript for KCNE4, a voltage-gated potassium (Kv) channel β subunit associated with human atrial fibrillation, was 8-fold more highly expressed in the male left ventricle compared with females in young adult C57BL/6 mice (P < 0.05). Similarly, Kv current density was 25% greater in ventricular myocytes from young adult males (P < 0.05). Germ-line Kcne4 deletion eliminated the sex-specific Kv current disparity by diminishing ventricular fast transient outward current (Ito,f) and slowly activating K(+) current (IK,slow1). Kcne4 deletion also reduced Kv currents in male mouse atrial myocytes, by >45% (P < 0.001). As we previously found for Kv4.2 (which generates mouse Ito,f), heterologously expressed KCNE4 functionally regulated Kv1.5 (the Kv α subunit that generates IKslow1 in mice). Of note, in postmenopausal female mice, ventricular repolarization was impaired by Kcne4 deletion, and ventricular Kcne4 expression increased to match that of males. Moreover, castration diminished male ventricular Kcne4 expression 2.8-fold, whereas 5α-dihydrotestosterone (DHT) implants in castrated mice increased Kcne4 expression >3-fold (P = 0.01) to match noncastrated levels. KCNE4 is thereby shown to be a DHT-regulated determinant of cardiac excitability and a molecular substrate for sex- and age-dependent cardiac arrhythmogenesis.
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Affiliation(s)
- Shawn M Crump
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Zhaoyang Hu
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Ritu Kant
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Daniel I Levy
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Steve A N Goldstein
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Geoffrey W Abbott
- *Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA; Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China; Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois, USA; and Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
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Lee SM, Nguyen D, Hu Z, Abbott GW. Kcne2 deletion promotes atherosclerosis and diet-dependent sudden death. J Mol Cell Cardiol 2015; 87:148-51. [PMID: 26307149 DOI: 10.1016/j.yjmcc.2015.08.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 08/12/2015] [Accepted: 08/12/2015] [Indexed: 02/05/2023]
Abstract
Coronary artery disease (CAD) is the leading cause of death worldwide. An estimated half of cases involve genetic predisposition. Sequence variants in human KCNE2, which encodes a cardiac and epithelial K(+) channel β subunit, cause inherited cardiac arrhythmias. Unexpectedly, human KCNE2 polymorphisms also associate with predisposition to atherosclerosis, with unestablished causality or mechanisms. Here, we report that germline Kcne2 deletion promotes atherosclerosis in mice, overcoming the relative resistance of this species to plaque deposition. In female western diet-fed mice, Kcne2 deletion increased plaque deposition >6-fold and also caused premature ventricular complexes and sudden death. The data establish causality for the first example of ion channel-linked atherosclerosis, and demonstrate that the severity of Kcne2-linked cardiac arrhythmias is strongly diet-dependent.
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Affiliation(s)
- Soo Min Lee
- Bioelectricity Laboratory, Dept. of Pharmacology, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Dara Nguyen
- Bioelectricity Laboratory, Dept. of Pharmacology, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Zhaoyang Hu
- Department of Anesthesiology and Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Pharmacology, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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Abriel H, Rougier JS, Jalife J. Ion channel macromolecular complexes in cardiomyocytes: roles in sudden cardiac death. Circ Res 2015; 116:1971-88. [PMID: 26044251 DOI: 10.1161/circresaha.116.305017] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The movement of ions across specific channels embedded on the membrane of individual cardiomyocytes is crucial for the generation and propagation of the cardiac electric impulse. Emerging evidence over the past 20 years strongly suggests that the normal electric function of the heart is the result of dynamic interactions of membrane ion channels working in an orchestrated fashion as part of complex molecular networks. Such networks work together with exquisite temporal precision to generate each action potential and contraction. Macromolecular complexes play crucial roles in transcription, translation, oligomerization, trafficking, membrane retention, glycosylation, post-translational modification, turnover, function, and degradation of all cardiac ion channels known to date. In addition, the accurate timing of each cardiac beat and contraction demands, a comparable precision on the assembly and organizations of sodium, calcium, and potassium channel complexes within specific subcellular microdomains, where physical proximity allows for prompt and efficient interaction. This review article, part of the Compendium on Sudden Cardiac Death, discusses the major issues related to the role of ion channel macromolecular assemblies in normal cardiac electric function and the mechanisms of arrhythmias leading to sudden cardiac death. It provides an idea of how these issues are being addressed in the laboratory and in the clinic, which important questions remain unanswered, and what future research will be needed to improve knowledge and advance therapy.
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Affiliation(s)
- Hugues Abriel
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.)
| | - Jean-Sébastien Rougier
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.)
| | - José Jalife
- From the Department of Clinical Research, University of Bern, Bern, Switzerland (H.A., J.-S.R.); Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor (J.J.); and Area of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (J.J.).
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The KCNE2 K⁺ channel regulatory subunit: Ubiquitous influence, complex pathobiology. Gene 2015; 569:162-72. [PMID: 26123744 DOI: 10.1016/j.gene.2015.06.061] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/15/2015] [Accepted: 06/23/2015] [Indexed: 02/05/2023]
Abstract
The KCNE single-span transmembrane subunits are encoded by five-member gene families in the human and mouse genomes. Primarily recognized for co-assembling with and functionally regulating the voltage-gated potassium channels, the broad influence of KCNE subunits in mammalian physiology belies their small size. KCNE2 has been widely studied since we first discovered one of its roles in the heart and its association with inherited and acquired human Long QT syndrome. Since then, physiological analyses together with human and mouse genetics studies have uncovered a startling array of functions for KCNE2, in the heart, stomach, thyroid and choroid plexus. The other side of this coin is the variety of interconnected disease manifestations caused by KCNE2 disruption, involving both excitable cells such as cardiomyocytes, and non-excitable, polarized epithelia. Kcne2 deletion in mice has been particularly instrumental in illustrating the potential ramifications within a monogenic arrhythmia syndrome, with removal of one piece revealing the unexpected complexity of the puzzle. Here, we review current knowledge of the function and pathobiology of KCNE2.
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37
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Ednie AR, Bennett ES. Reduced sialylation impacts ventricular repolarization by modulating specific K+ channel isoforms distinctly. J Biol Chem 2014; 290:2769-83. [PMID: 25525262 DOI: 10.1074/jbc.m114.605139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated K(+) channels (Kv) are responsible for repolarizing excitable cells and can be heavily glycosylated. Cardiac Kv activity is indispensable where even minimal reductions in function can extend action potential duration, prolong QT intervals, and ultimately contribute to life-threatening arrhythmias. Diseases such as congenital disorders of glycosylation often cause significant cardiac phenotypes that can include arrhythmias. Here we investigated the impact of reduced sialylation on ventricular repolarization through gene deletion of the sialyltransferase ST3Gal4. ST3Gal4-deficient mice (ST3Gal4(-/-)) had prolonged QT intervals with a concomitant increase in ventricular action potential duration. Ventricular apex myocytes isolated from ST3Gal4(-/-) mice demonstrated depolarizing shifts in activation gating of the transient outward (Ito) and delayed rectifier (IKslow) components of K(+) current with no change in maximum current densities. Consistently, similar protein expression levels of the three Kv isoforms responsible for Ito and IKslow were measured for ST3Gal4(-/-) versus controls. However, novel non-enzymatic sialic acid labeling indicated a reduction in sialylation of ST3Gal4(-/-) ventricular Kv4.2 and Kv1.5, which contribute to Ito and IKslow, respectively. Thus, we describe here a novel form of regulating cardiac function through the activities of a specific glycogene product. Namely, reduced ST3Gal4 activity leads to a loss of isoform-specific Kv sialylation and function, thereby limiting Kv activity during the action potential and decreasing repolarization rate, which likely contributes to prolonged ventricular repolarization. These studies elucidate a novel role for individual glycogene products in contributing to a complex network of cardiac regulation under normal and pathologic conditions.
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Affiliation(s)
- Andrew R Ednie
- From the Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Eric S Bennett
- From the Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
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38
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Nielsen JB, Bentzen BH, Olesen MS, David JP, Olesen SP, Haunsø S, Svendsen JH, Schmitt N. Gain-of-function mutations in potassium channel subunit KCNE2 associated with early-onset lone atrial fibrillation. Biomark Med 2014; 8:557-70. [PMID: 24796621 DOI: 10.2217/bmm.13.137] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Atrial fibrillation (AF) is the most common cardiac arrhythmia. Disturbances in cardiac potassium conductance are considered as one of the disease mechanisms in AF. We aimed to investigate if mutations in potassium-channel β-subunits KCNE2 and KCNE3 are associated with early-onset lone AF. METHODS & RESULTS The coding regions of KCNE2 and KCNE3 were bidirectionally sequenced in 192 unrelated patients diagnosed with early-onset lone AF (<40 years). Two nonsynonymous missense mutations were identified in KCNE2 (M23L and I57T). Both mutations were absent in a healthy control group (n=1500 alleles). Electrophysiological investigations were performed for both mutations in combination with candidate pore-forming α-subunits KV7.1, KV11.1, KV4.3 and KV1.5. A significant gain-of-function effect was observed upon coexpression with KV7.1 and KV7.1+KCNE1. Confocal imaging found no differences in subcellular localization. No disease-suspected mutations were identified in KCNE3. CONCLUSION We identified two KCNE2 gain-of-function missense mutations that seem to increase the susceptibility of early-onset lone AF. These results confirm previous findings indicating that gain-of-function in the slow delayed rectifier potassium current might be involved in the pathogenesis of AF.
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Affiliation(s)
- Jonas Bille Nielsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
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Salsbury G, Cambridge EL, McIntyre Z, Arends MJ, Karp NA, Isherwood C, Shannon C, Hooks Y, Ramirez-Solis R, Adams DJ, White JK, Speak AO. Disruption of the potassium channel regulatory subunit KCNE2 causes iron-deficient anemia. Exp Hematol 2014; 42:1053-8.e1. [PMID: 25127743 PMCID: PMC4271779 DOI: 10.1016/j.exphem.2014.07.269] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/04/2014] [Accepted: 07/08/2014] [Indexed: 12/21/2022]
Abstract
Iron homeostasis is a dynamic process that is tightly controlled to balance iron uptake, storage, and export. Reduction of dietary iron from the ferric to the ferrous form is required for uptake by solute carrier family 11 (proton-coupled divalent metal ion transporters), member 2 (Slc11a2) into the enterocytes. Both processes are proton dependent and have led to the suggestion of the importance of acidic gastric pH for the absorption of dietary iron. Potassium voltage-gated channel subfamily E, member 2 (KCNE2), in combination with potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1), form a gastric potassium channel essential for gastric acidification. Deficiency of either Kcne2 or Kcnq1 results in achlorhydia, gastric hyperplasia, and neoplasia, but the impact on iron absorption has not, to our knowledge, been investigated. Here we report that Kcne2-deficient mice, in addition to the previously reported phenotypes, also present with iron-deficient anemia. Interestingly, impaired function of KCNQ1 results in iron-deficient anemia in Jervell and Lange-Nielsen syndrome patients. We speculate that impaired function of KCNE2 could result in the same clinical phenotype.
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Affiliation(s)
- Grace Salsbury
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Emma L Cambridge
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Zoe McIntyre
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Mark J Arends
- University of Edinburgh Division of Pathology, Institute of Genetics & Molecular Medicine, Western General Hospital, Edinburgh, United Kingdom
| | - Natasha A Karp
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Christopher Isherwood
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Carl Shannon
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Yvette Hooks
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | | | - Ramiro Ramirez-Solis
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - David J Adams
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Jacqueline K White
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Anneliese O Speak
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, United Kingdom.
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40
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KCNE2 modulates cardiac L-type Ca2+ channel. J Mol Cell Cardiol 2014; 72:208-18. [DOI: 10.1016/j.yjmcc.2014.03.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 03/05/2014] [Accepted: 03/18/2014] [Indexed: 11/19/2022]
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Affiliation(s)
- Geoffrey W Abbott
- 1360 Medical Surge II, Dept. of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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42
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Nerbonne JM. Mouse models of arrhythmogenic cardiovascular disease: challenges and opportunities. Curr Opin Pharmacol 2014; 15:107-14. [PMID: 24632325 DOI: 10.1016/j.coph.2014.02.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 02/04/2014] [Accepted: 02/05/2014] [Indexed: 12/27/2022]
Abstract
Arrhythmogenic cardiovascular disease is associated with significant morbidity and mortality and, in spite of therapeutic advances, remains an enormous public health burden. The scope of this problem motivates efforts to delineate the molecular, cellular and systemic mechanisms underlying increased arrhythmia risk in inherited and acquired cardiac and systemic disease. The mouse is used increasingly in these efforts owing to the ease with which genetic strategies can be exploited and mechanisms can be probed. The question then arises whether the mouse has proven to be a useful model system to delineate arrhythmogenic cardiovascular disease mechanisms. Rather than trying to provide a definite answer, the goal here is to consider the issues that arise when using mouse models and to highlight the opportunities.
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Affiliation(s)
- Jeanne M Nerbonne
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO 63110, USA; Department of Internal Medicine, Washington University Medical School, St. Louis, MO 63110, USA.
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Crump SM, Abbott GW. Arrhythmogenic KCNE gene variants: current knowledge and future challenges. Front Genet 2014; 5:3. [PMID: 24478792 PMCID: PMC3900874 DOI: 10.3389/fgene.2014.00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/04/2014] [Indexed: 11/13/2022] Open
Abstract
There are twenty-five known inherited cardiac arrhythmia susceptibility genes, all of which encode either ion channel pore-forming subunits or proteins that regulate aspects of ion channel biology such as function, trafficking, and localization. The human KCNE gene family comprises five potassium channel regulatory subunits, sequence variants in each of which are associated with cardiac arrhythmias. KCNE gene products exhibit promiscuous partnering and in some cases ubiquitous expression, hampering efforts to unequivocally correlate each gene to specific native potassium currents. Likewise, deducing the molecular etiology of cardiac arrhythmias in individuals harboring rare KCNE gene variants, or more common KCNE polymorphisms, can be challenging. In this review we provide an update on putative arrhythmia-causing KCNE gene variants, and discuss current thinking and future challenges in the study of molecular mechanisms of KCNE-associated cardiac rhythm disturbances.
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Affiliation(s)
- Shawn M Crump
- Bioelectricity Laboratory, Department of Pharmacology, Department of Physiology and Biophysics, School of Medicine, University of California Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology, Department of Physiology and Biophysics, School of Medicine, University of California Irvine, CA, USA
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Hu Z, Kant R, Anand M, King EC, Krogh-Madsen T, Christini DJ, Abbott GW. Kcne2 deletion creates a multisystem syndrome predisposing to sudden cardiac death. ACTA ACUST UNITED AC 2014; 7:33-42. [PMID: 24403551 DOI: 10.1161/circgenetics.113.000315] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Sudden cardiac death (SCD) is the leading global cause of mortality, exhibiting increased incidence in patients with diabetes mellitus. Ion channel gene perturbations provide a well-established ventricular arrhythmogenic substrate for SCD. However, most arrhythmia-susceptibility genes, including the KCNE2 K(+) channel β subunit, are expressed in multiple tissues, suggesting potential multiplex SCD substrates. METHODS AND RESULTS Using whole-transcript transcriptomics, we uncovered cardiac angiotensinogen upregulation and remodeling of cardiac angiotensinogen interaction networks in P21 Kcne2(-/-) mouse pups and adrenal remodeling consistent with metabolic syndrome in adult Kcne2(-/-) mice. This led to the discovery that Kcne2 disruption causes multiple acknowledged SCD substrates of extracardiac origin: diabetes mellitus, hypercholesterolemia, hyperkalemia, anemia, and elevated angiotensin II. Kcne2 deletion was also a prerequisite for aging-dependent QT prolongation, ventricular fibrillation and SCD immediately after transient ischemia, and fasting-dependent hypoglycemia, myocardial ischemia, and AV block. CONCLUSIONS Disruption of a single, widely expressed arrhythmia-susceptibility gene can generate a multisystem syndrome comprising manifold electric and systemic substrates and triggers of SCD. This paradigm is expected to apply to other arrhythmia-susceptibility genes, the majority of which encode ubiquitously expressed ion channel subunits or regulatory proteins.
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Affiliation(s)
- Zhaoyang Hu
- Bioelectricity Laboratory, Departments of Pharmacology and Physiology and Biophysics, School of Medicine, University of California, Irvine
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Du C, El Harchi A, Zhang H, Hancox JC. Modification by KCNE1 variants of the hERG potassium channel response to premature stimulation and to pharmacological inhibition. Physiol Rep 2013; 1:e00175. [PMID: 24400172 PMCID: PMC3871485 DOI: 10.1002/phy2.175] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/02/2013] [Accepted: 11/04/2013] [Indexed: 01/08/2023] Open
Abstract
human Ether-à-go-go-Related Gene (hERG) encodes the pore-forming subunit of cardiac rapid delayed rectifier K(+) current (I Kr) channels, which play important roles in ventricular repolarization, in protecting the myocardium from unwanted premature stimuli, and in drug-induced Long QT Syndrome (LQTS). KCNE1, a small transmembrane protein, can coassemble with hERG. However, it is not known how KCNE1 variants influence the channel's response to premature stimuli or if they influence the sensitivity of hERG to pharmacological inhibition. Accordingly, whole-cell patch-clamp measurements of hERG current (I hERG) were made at 37°C from hERG channels coexpressed with either wild-type (WT) KCNE1 or with one of three KCNE1 variants (A8V, D76N, and D85N). Under both conventional voltage clamp and ventricular action potential (AP) clamp, the amplitude of I hERG was smaller for A8V, D76N, and D85N KCNE1 + hERG than for WT KCNE1 + hERG. Using paired AP commands, with the second AP waveform applied at varying time intervals following the first to mimic premature ventricular excitation, the response of I hERG carried by each KCNE1 variant was reduced compared to that with WT KCNE1 + hERG. The I hERG blocking potency of the antiarrhythmic drug quinidine was similar between WT KCNE1 and the three KCNE1 variants. However, the I hERG inhibitory potency of the antibiotic clarithromycin and of the prokinetic drug cisapride was altered by KCNE1 variants. These results demonstrate that naturally occurring KCNE1 variants can reduce the response of hERG channels to premature excitation and also alter the sensitivity of hERG channels to inhibition by some drugs linked to acquired LQTS.
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Affiliation(s)
- Chunyun Du
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Medical Sciences Building, University of Bristol Bristol, BS8 1TD, U.K
| | - Aziza El Harchi
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Medical Sciences Building, University of Bristol Bristol, BS8 1TD, U.K
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, University of Manchester Manchester, M13 9PL, U.K
| | - Jules C Hancox
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Medical Sciences Building, University of Bristol Bristol, BS8 1TD, U.K
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Hu Z, Crump SM, Anand M, Kant R, Levi R, Abbott GW. Kcne3 deletion initiates extracardiac arrhythmogenesis in mice. FASEB J 2013; 28:935-45. [PMID: 24225147 DOI: 10.1096/fj.13-241828] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mutations in the human KCNE3 potassium channel ancillary subunit gene are associated with life-threatening ventricular arrhythmias. Most genes underlying inherited cardiac arrhythmias, including KCNE3, are not exclusively expressed in the heart, suggesting potentially complex disease etiologies. Here we investigated mechanisms of KCNE3-linked arrhythmogenesis in Kcne3(-/-) mice using real-time qPCR, echo- and electrocardiography, ventricular myocyte patch-clamp, coronary artery ligation/reperfusion, blood analysis, cardiac synaptosome exocytosis, microarray and pathway analysis, and multitissue histology. Kcne3 transcript was undetectable in adult mouse atria, ventricles, and adrenal glands, but Kcne3(-/-) mice exhibited 2.3-fold elevated serum aldosterone (P=0.003) and differentially expressed gene networks consistent with an adrenal-targeted autoimmune response. Furthermore, 8/8 Kcne3(-/-) mice vs. 0/8 Kcne3(+/+) mice exhibited an activated-lymphocyte adrenal infiltration (P=0.0002). Kcne3 deletion also caused aldosterone-dependent ventricular repolarization delay (19.6% mean QTc prolongation in females; P<0.05) and aldosterone-dependent predisposition to postischemia arrhythmogenesis. Thus, 5/11 Kcne3(-/-) mice vs. 0/10 Kcne3(+/+) mice exhibited sustained ventricular tachycardia during reperfusion (P<0.05). Kcne3 deletion is therefore arrhythmogenic by a novel mechanism in which secondary hyperaldosteronism, associated with an adrenal-specific lymphocyte infiltration, impairs ventricular repolarization. The findings highlight the importance of considering extracardiac pathogenesis when investigating arrhythmogenic mechanisms, even in inherited, monogenic channelopathies.
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Affiliation(s)
- Zhaoyang Hu
- 1360 Medical Surge II, Department of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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Foeger NC, Wang W, Mellor RL, Nerbonne JM. Stabilization of Kv4 protein by the accessory K(+) channel interacting protein 2 (KChIP2) subunit is required for the generation of native myocardial fast transient outward K(+) currents. J Physiol 2013; 591:4149-66. [PMID: 23713033 DOI: 10.1113/jphysiol.2013.255836] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The fast transient outward K(+) current (Ito,f) underlies the early phase of myocardial action potential repolarization, contributing importantly to the coordinated propagation of activity in the heart and to the generation of normal cardiac rhythms. Native Ito,f channels reflect the tetrameric assembly of Kv4 pore-forming (α) subunits, and previous studies suggest roles for accessory and regulatory proteins in controlling the cell surface expression and the biophysical properties of Kv4-encoded Ito,f channels. Here, we demonstrate that the targeted deletion of the cytosolic accessory subunit, K(+) channel interacting protein 2 (KChIP2), results in the complete loss of the Kv4.2 protein, the α subunit critical for the generation of mouse ventricular Ito,f. Expression of the Kcnd2 (Kv4.2) transcript in KChIP2(-/-) ventricles, however, is unaffected. The loss of the Kv4.2 protein results in the elimination of Ito,f in KChIP2(-/-) ventricular myocytes. In parallel with the elimination of Ito,f, the slow transient outward K(+) current (Ito,s) is upregulated and voltage-gated Ca(2+) currents (ICa,L) are decreased. In addition, surface electrocardiograms and ventricular action potential waveforms in KChIP2(-/-) and wild-type mice are not significantly different, suggesting that the upregulation of Ito,s and the reduction in ICa,L compensate for the loss of Ito,f. Additional experiments revealed that Ito,f is not 'rescued' by adenovirus-mediated expression of KChIP2 in KChIP2(-/-) myocytes, although ICa,L densities are increased. Taken together, these results demonstrate that association with KChIP2 early in the biosynthetic pathway and KChIP2-mediated stabilization of Kv4 protein are critical determinants of native cardiac Ito,f channel expression.
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Affiliation(s)
- Nicholas C Foeger
- J. M. Nerbonne: Department of Developmental Biology, Washington University School of Medicine, Campus Box 8103, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Nawathe PA, Kryukova Y, Oren RV, Milanesi R, Clancy CE, Lu JT, Moss AJ, Difrancesco D, Robinson RB. An LQTS6 MiRP1 mutation suppresses pacemaker current and is associated with sinus bradycardia. J Cardiovasc Electrophysiol 2013; 24:1021-7. [PMID: 23631727 DOI: 10.1111/jce.12163] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/20/2012] [Accepted: 03/13/2013] [Indexed: 01/20/2023]
Abstract
BACKGROUND Sinus node (SN) dysfunction is observed in some long-QT syndrome (LQTS) patients, but has not been studied as a function of LQTS genotype. LQTS6 involves mutations in the hERG β-subunit MiRP1, which also interacts with hyperpolarization-activated, cyclic nucleotide gated (HCN) channels-the molecular correlate of SN pacemaker current (If ). An LQTS registry search identified a 55-year male with M54T MiRP1 mutation, history of sinus bradycardia (39-56 bpm), and prolonged QTc. OBJECTIVE We tested if LQTS6 incorporates sinus bradycardia due to abnormal If . METHODS We transiently co-transfected neonatal rat ventricular myocytes (to study currents in a myocyte background) with human HCN4 (hHCN4, primary SN isoform) or human HCN2 (hHCN2) and one of the following: empty vector, wild-type hMiRP1 (WT), M54T hMiRP1 (M54T). Current amplitude, voltage dependence, and kinetics were measured by whole cell patch clamp. RESULTS M54T co-expression decreased HCN4 current density by 80% compared to hHCN4 alone or with WT, and also slowed HCN4 activation at physiologically relevant voltages. Neither WT nor M54T altered HCN4 voltage dependence. A computer simulation predicts that these changes in HCN4 current would decrease rate and be additive with published effects of M54T mutation on hERG kinetics on rate. CONCLUSIONS We conclude that M54T LQTS6 mutation can cause sinus bradycardia through effects on both hERG and HCN currents. Patients with other LQTS6 mutations should be examined for SN dysfunction, and the effect on HCN current determined.
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Köhncke C, Lisewski U, Schleußner L, Gaertner C, Reichert S, Roepke TK. Isolation and Kv channel recordings in murine atrial and ventricular cardiomyocytes. J Vis Exp 2013:e50145. [PMID: 23524949 DOI: 10.3791/50145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
KCNE genes encode for a small family of Kv channel ancillary subunits that form heteromeric complexes with Kv channel alpha subunits to modify their functional properties. Mutations in KCNE genes have been found in patients with cardiac arrhythmias such as the long QT syndrome and/or atrial fibrillation. However, the precise molecular pathophysiology that leads to these diseases remains elusive. In previous studies the electrophysiological properties of the disease causing mutations in these genes have mostly been studied in heterologous expression systems and we cannot be sure if the reported effects can directly be translated into native cardiomyocytes. In our laboratory we therefore use a different approach. We directly study the effects of KCNE gene deletion in isolated cardiomyocytes from knockout mice by cellular electrophysiology - a unique technique that we describe in this issue of the Journal of Visualized Experiments. The hearts from genetically engineered KCNE mice are rapidly excised and mounted onto a Langendorff apparatus by aortic cannulation. Free Ca(2+) in the myocardium is bound by EGTA, and dissociation of cardiac myocytes is then achieved by retrograde perfusion of the coronary arteries with a specialized low Ca(2+) buffer containing collagenase. Atria, free right ventricular wall and the left ventricle can then be separated by microsurgical techniques. Calcium is then slowly added back to isolated cardiomyocytes in a multiple step comprising washing procedure. Atrial and ventricular cardiomyocytes of healthy appearance with no spontaneous contractions are then immediately subjected to electrophysiological analyses by patch clamp technique or other biochemical analyses within the first 6 hours following isolation.
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Affiliation(s)
- Clemens Köhncke
- Experimental and Clinical Research Center, Charité Medical Faculty and Max-Delbrück Center for Molecular Medicine
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Solé L, Vallejo-Gracia A, Roig SR, Serrano-Albarrás A, Marruecos L, Manils J, Gómez D, Soler C, Felipe A. KCNE gene expression is dependent on the proliferation and mode of activation of leukocytes. Channels (Austin) 2013; 7:85-96. [PMID: 23327879 DOI: 10.4161/chan.23258] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Voltage-dependent K (+) (Kv) channels are tightly regulated during the immune system response. Leukocytes have a limited repertoire of Kv channels, whose physiological role is under intense investigation. A functional Kv channel is an oligomeric complex composed of pore-forming and ancillary subunits. The KCNE gene family is a novel group of modulatory Kv channel elements in leukocytes. Here, we characterized the gene expression of KCNEs (1-5) in leukocytes and investigated their regulation during leukocyte proliferation and mode of activation. Murine bone-marrow-derived macrophages, human Jurkat T-lymphocytes and human Raji B-cells were analyzed. KCNEs (1-5) are expressed in all leukocytes lineages. Most KCNE mRNAs show cell cycle-dependent regulation and are differentially regulated under specific insults. Our results further suggest a new and yet undefined physiological role for KCNE subunits in the immune system. Putative associations of these ancillary proteins with Kv channels would yield a wide variety of biophysically and pharmacologically distinct channels that fine-tune the immunological response.
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Affiliation(s)
- Laura Solé
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular; Institut de Biomedicina, Universitat de Barcelona, Barcelona, Spain
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