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Davis J, Cornwell JD, Campagna N, Guo J, Li W, Yang T, Wang T, Zhang S. Rescue of expression and function of long QT syndrome-causing mutant hERG channels by enhancing channel stability in the plasma membrane. J Biol Chem 2024; 300:107526. [PMID: 38960041 DOI: 10.1016/j.jbc.2024.107526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/21/2024] [Accepted: 06/23/2024] [Indexed: 07/05/2024] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes the Kv11.1 (or hERG) channel that conducts the rapidly activating delayed rectifier potassium current (IKr). Naturally occurring mutations in hERG impair the channel function and cause long QT syndrome type 2. Many missense hERG mutations lead to a lack of channel expression on the cell surface, representing a major mechanism for the loss-of-function of mutant channels. While it is generally thought that a trafficking defect underlies the lack of channel expression on the cell surface, in the present study, we demonstrate that the trafficking defective mutant hERG G601S can reach the plasma membrane but is unstable and quickly degrades, which is akin to WT hERG channels under low K+ conditions. We previously showed that serine (S) residue at 624 in the innermost position of the selectivity filter of hERG is involved in hERG membrane stability such that substitution of serine 624 with threonine (S624T) enhances hERG stability and renders hERG insensitive to low K+ culture. Here, we report that the intragenic addition of S624T substitution to trafficking defective hERG mutants G601S, N470D, and P596R led to a complete rescue of the function of these otherwise loss-of-function mutant channels to a level similar to the WT channel, representing the most effective rescue means for the function of mutant hERG channels. These findings not only provide novel insights into hERG mutation-mediated channel dysfunction but also point to the critical role of S624 in hERG stability on the plasma membrane.
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Affiliation(s)
- Jordan Davis
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - James D Cornwell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Noah Campagna
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tingzhong Wang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
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2
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Reisqs JB, Qu YS, Boutjdir M. Ion channel trafficking implications in heart failure. Front Cardiovasc Med 2024; 11:1351496. [PMID: 38420267 PMCID: PMC10899472 DOI: 10.3389/fcvm.2024.1351496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/25/2024] [Indexed: 03/02/2024] Open
Abstract
Heart failure (HF) is recognized as an epidemic in the contemporary world, impacting around 1%-2% of the adult population and affecting around 6 million Americans. HF remains a major cause of mortality, morbidity, and poor quality of life. Several therapies are used to treat HF and improve the survival of patients; however, despite these substantial improvements in treating HF, the incidence of HF is increasing rapidly, posing a significant burden to human health. The total cost of care for HF is USD 69.8 billion in 2023, warranting a better understanding of the mechanisms involved in HF. Among the most serious manifestations associated with HF is arrhythmia due to the electrophysiological changes within the cardiomyocyte. Among these electrophysiological changes, disruptions in sodium and potassium currents' function and trafficking, as well as calcium handling, all of which impact arrhythmia in HF. The mechanisms responsible for the trafficking, anchoring, organization, and recycling of ion channels at the plasma membrane seem to be significant contributors to ion channels dysfunction in HF. Variants, microtubule alterations, or disturbances of anchoring proteins lead to ion channel trafficking defects and the alteration of the cardiomyocyte's electrophysiology. Understanding the mechanisms of ion channels trafficking could provide new therapeutic approaches for the treatment of HF. This review provides an overview of the recent advances in ion channel trafficking in HF.
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Affiliation(s)
- Jean-Baptiste Reisqs
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
| | - Yongxia Sarah Qu
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Cardiology, New York Presbyterian Brooklyn Methodist Hospital, New York, NY, United States
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY, United States
- Department of Medicine, New York University Grossman School of Medicine, New York, NY, United States
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3
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Campagna N, Wall E, Lee K, Guo J, Li W, Yang T, Baranchuk A, El-Diasty M, Zhang S. Differential Effects of Remdesivir and Lumacaftor on Homomeric and Heteromeric hERG Channels. Mol Pharmacol 2023; 104:164-173. [PMID: 37419691 DOI: 10.1124/molpharm.123.000708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/31/2023] [Accepted: 06/08/2023] [Indexed: 07/09/2023] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes for the pore-forming subunit of the channel that conducts the rapidly activating delayed K+ current (IKr) in the heart. The hERG channel is important for cardiac repolarization, and reduction of its expression in the plasma membrane due to mutations causes long QT syndrome type 2 (LQT2). As such, promoting hERG membrane expression is a strategy to rescue mutant channel function. In the present study, we applied patch clamp, western blots, immunocytochemistry, and quantitative reverse transcription polymerase chain reaction techniques to investigate the rescue effects of two drugs, remdesivir and lumacaftor, on trafficking-defective mutant hERG channels. As our group has recently reported that the antiviral drug remdesivir increases wild-type (WT) hERG current and surface expression, we studied the effects of remdesivir on trafficking-defective LQT2-causing hERG mutants G601S and R582C expressed in HEK293 cells. We also investigated the effects of lumacaftor, a drug used to treat cystic fibrosis, that promotes CFTR protein trafficking and has been shown to rescue membrane expression of some hERG mutations. Our results show that neither remdesivir nor lumacaftor rescued the current or cell-surface expression of homomeric mutants G601S and R582C. However, remdesivir decreased while lumacaftor increased the current and cell-surface expression of heteromeric channels formed by WT hERG and mutant G601S or R582C hERG. We concluded that drugs can differentially affect homomeric WT and heteromeric WT+G601S (or WT+R582C) hERG channels. These findings extend our understanding of drug-channel interaction and may have clinical implications for patients with hERG mutations. SIGNIFICANCE STATEMENT: Various naturally occurring mutations in a cardiac potassium channel called hERG can impair channel function by decreasing cell-surface channel expression, resulting in cardiac electrical disturbances and even sudden cardiac death. Promotion of cell-surface expression of mutant hERG channels represents a strategy to rescue channel function. This work demonstrates that drugs such as remdesivir and lumacaftor can differently affect homomeric and heteromeric mutant hERG channels, which have biological and clinical implications.
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Affiliation(s)
- Noah Campagna
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Erika Wall
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Kevin Lee
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Adrian Baranchuk
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Mohammad El-Diasty
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
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4
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Meier S, Grundland A, Dobrev D, Volders PG, Heijman J. In silico analysis of the dynamic regulation of cardiac electrophysiology by K v 11.1 ion-channel trafficking. J Physiol 2023; 601:2711-2731. [PMID: 36752166 PMCID: PMC10313819 DOI: 10.1113/jp283976] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/30/2023] [Indexed: 02/09/2023] Open
Abstract
Cardiac electrophysiology is regulated by continuous trafficking and internalization of ion channels occurring over minutes to hours. Kv 11.1 (also known as hERG) underlies the rapidly activating delayed-rectifier K+ current (IKr ), which plays a major role in cardiac ventricular repolarization. Experimental characterization of the distinct temporal effects of genetic and acquired modulators on channel trafficking and gating is challenging. Computer models are instrumental in elucidating these effects, but no currently available model incorporates ion-channel trafficking. Here, we present a novel computational model that reproduces the experimentally observed production, forward trafficking, internalization, recycling and degradation of Kv 11.1 channels, as well as their modulation by temperature, pentamidine, dofetilide and extracellular K+ . The acute effects of these modulators on channel gating were also incorporated and integrated with the trafficking model in the O'Hara-Rudy human ventricular cardiomyocyte model. Supraphysiological dofetilide concentrations substantially increased Kv 11.1 membrane levels while also producing a significant channel block. However, clinically relevant concentrations did not affect trafficking. Similarly, severe hypokalaemia reduced Kv 11.1 membrane levels based on long-term culture data, but had limited effect based on short-term data. By contrast, clinically relevant elevations in temperature acutely increased IKr due to faster kinetics, while after 24 h, IKr was decreased due to reduced Kv 11.1 membrane levels. The opposite was true for lower temperatures. Taken together, our model reveals a complex temporal regulation of cardiac electrophysiology by temperature, hypokalaemia, and dofetilide through competing effects on channel gating and trafficking, and provides a framework for future studies assessing the role of impaired trafficking in cardiac arrhythmias. KEY POINTS: Kv 11.1 channels underlying the rapidly activating delayed-rectifier K+ current are important for ventricular repolarization and are continuously shuttled from the cytoplasm to the plasma membrane and back over minutes to hours. Kv 11.1 gating and trafficking are modulated by temperature, drugs and extracellular K+ concentration but experimental characterization of their combined effects is challenging. Computer models may facilitate these analyses, but no currently available model incorporates ion-channel trafficking. We introduce a new two-state ion-channel trafficking model able to reproduce a wide range of experimental data, along with the effects of modulators of Kv 11.1 channel functioning and trafficking. The model reveals complex dynamic regulation of ventricular repolarization by temperature, extracellular K+ concentration and dofetilide through opposing acute (millisecond) effects on Kv 11.1 gating and long-term (hours) modulation of Kv 11.1 trafficking. This in silico trafficking framework provides a tool to investigate the roles of acute and long-term processes on arrhythmia promotion and maintenance.
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Affiliation(s)
- Stefan Meier
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Faculty of Health, Medicine, and Life Sciences, Maastricht University and Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Adaïa Grundland
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Faculty of Health, Medicine, and Life Sciences, Maastricht University and Maastricht University Medical Center+, Maastricht, The Netherlands
- Department of Data Science and Knowledge Engineering, Faculty of Science and Engineering, Maastricht University, Maastricht, The Netherlands
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University of Duisburg-Essen, Essen, Germany
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montréal, Quebec, Canada
| | - Paul G.A. Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Faculty of Health, Medicine, and Life Sciences, Maastricht University and Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Faculty of Health, Medicine, and Life Sciences, Maastricht University and Maastricht University Medical Center+, Maastricht, The Netherlands
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5
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Molitor N, Hofer D, Çimen T, Gasperetti A, Akdis D, Costa S, Jenni R, Breitenstein A, Wolber T, Winnik S, Fokstuen S, Fu G, Medeiros-Domingo A, Ruschitzka F, Brunckhorst C, Duru F, Saguner AM. Evolution and triggers of defibrillator shocks in patients with arrhythmogenic right ventricular cardiomyopathy. Heart 2023:heartjnl-2022-321739. [PMID: 36889907 DOI: 10.1136/heartjnl-2022-321739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 02/13/2023] [Indexed: 03/10/2023] Open
Abstract
INTRODUCTION Implantable cardioverter-defibrillators (ICDs) can prevent sudden cardiac death due to ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). The aim of our study was to assess the cumulative burden, evolution and potential triggers of appropriate ICD shocks during long-term follow-up, which may help to reduce and further refine individual arrhythmic risk in this challenging disease. METHODS This retrospective cohort study included 53 patients with definite ARVC according to the 2010 Task Force Criteria from the multicentre Swiss ARVC Registry with an implanted ICD for primary or secondary prevention. Follow-up was conducted by assessing all available patient records from patient visits, hospitalisations, blood samples, genetic analysis, as well as device interrogation and tracings. RESULTS Fifty-three patients (male 71.7%, mean age 43±2.2 years, genotype positive 58.5%) were analysed during a median follow-up of 7.9 (IQR 10) years. In 29 (54.7%) patients, 177 appropriate ICD shocks associated with 71 shock episodes occurred. Median time to first appropriate ICD shock was 2.8 (IQR 3.6) years. Long-term risk of shocks remained high throughout long-term follow-up. Shock episodes occurred mainly during daytime (91.5%, n=65) and without seasonal preference. We identified potentially reversible triggers in 56 of 71 (78.9%) appropriate shock episodes, the main triggers representing physical activity, inflammation and hypokalaemia. CONCLUSION The long-term risk of appropriate ICD shocks in patients with ARVC remains high during long-term follow-up. Ventricular arrhythmias occur more often during daytime, without seasonal preference. Reversible triggers are frequent with the most common triggers for appropriate ICD shocks being physical activity, inflammation and hypokalaemia in this patient population.
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Affiliation(s)
- Nadine Molitor
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Daniel Hofer
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Tolga Çimen
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Alessio Gasperetti
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland.,Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, Maryland, US
| | - Deniz Akdis
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland.,Division of Cardiology, GZO - Regional Health Center, Wetzikon, Switzerland
| | - Sarah Costa
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Rolf Jenni
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Alexander Breitenstein
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Thomas Wolber
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Stephan Winnik
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Siv Fokstuen
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland.,Genetic Medicine division, Diagnostic Department, Hôpitaux Universitaires de Genève, Genève, Switzerland
| | - Guan Fu
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | | | - Frank Ruschitzka
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Corinna Brunckhorst
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Firat Duru
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Ardan M Saguner
- Cardiology, Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
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Shen R, Zuo D, Chen K, Yin Y, Tang K, Hou S, Han B, Xu Y, Liu Z, Chen H. K2P1 leak cation channels contribute to ventricular ectopic beats and sudden death under hypokalemia. FASEB J 2022; 36:e22455. [PMID: 35899468 DOI: 10.1096/fj.202200707r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/28/2022] [Accepted: 07/06/2022] [Indexed: 11/11/2022]
Abstract
Hypokalemia causes ectopic heartbeats, but the mechanisms underlying such cardiac arrhythmias are not understood. In reduced serum K+ concentrations that occur under hypokalemia, K2P1 two-pore domain K+ channels change ion selectivity and switch to conduct inward leak cation currents, which cause aberrant depolarization of resting potential and induce spontaneous action potential of human cardiomyocytes. K2P1 is expressed in the human heart but not in mouse hearts. We test the hypothesis that K2P1 leak cation channels contribute to ectopic heartbeats under hypokalemia, by analysis of transgenic mice, which conditionally express induced K2P1 specifically in hearts, mimicking K2P1 channels in the human heart. Conditional expression of induced K2P1 specifically in the heart of hypokalemic mice results in multiple types of ventricular ectopic beats including single and multiple ventricular premature beats as well as ventricular tachycardia and causes sudden death. In isolated mouse hearts that express induced K2P1, sustained ventricular fibrillation occurs rapidly after perfusion with low K+ concentration solutions that mimic hypokalemic conditions. These observed phenotypes occur rarely in control mice or in the hearts that lack K2P1 expression. K2P1-expressing mouse cardiomyocytes of transgenic mice much more frequently fire abnormal single and/or rhythmic spontaneous action potential in hypokalemic conditions, compared to wild type mouse cardiomyocytes without K2P1 expression. These findings confirm that K2P1 leak cation channels induce ventricular ectopic beats and sudden death of transgenic mice with hypokalemia and imply that K2P1 leak cation channels may play a critical role in human ectopic heartbeats under hypokalemia.
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Affiliation(s)
- Rongrong Shen
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Dongchuan Zuo
- Key Laboratory of Medical Electrophysiology, Institute of Cardiovascular Research, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Southwest Medical University, Luzhou, China.,Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Kuihao Chen
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA.,Department of Pharmacology, Ningbo University School of Medicine, Ningbo, China
| | - Yiheng Yin
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Kai Tang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Shangwei Hou
- Key Laboratory for Translational Research and Innovative Therapeutics of Gastrointestinal Oncology, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bo Han
- Key Laboratory for Translational Research and Innovative Therapeutics of Gastrointestinal Oncology, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yawei Xu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Zheng Liu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China.,Cryo-Electron Microscopy Center, Southern University of Science and Technology, Shenzhen, China
| | - Haijun Chen
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
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7
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Metabolic and electrolyte abnormalities as risk factors in drug-induced long QT syndrome. Biophys Rev 2022; 14:353-367. [PMID: 35103080 PMCID: PMC8792523 DOI: 10.1007/s12551-022-00929-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/04/2022] [Indexed: 02/06/2023] Open
Abstract
Drug-induced long QT syndrome (diLQTS) is the phenomenon by which the administration of drugs causes prolongation of cardiac repolarisation and leads to an increased risk of the ventricular tachycardia known as torsades de pointes (TdP). In most cases of diLQTS, the primary molecular target is the human ether-à-go-go-related gene protein (hERG) potassium channel, which carries the rapid delayed rectifier current (IKr) in the heart. However, the proarrhythmic risk associated with drugs that block hERG can be modified in patients by a range of environmental- and disease-related factors, such as febrile temperatures, alterations in pH, dyselectrolytaemias such as hypokalaemia and hypomagnesemia and coadministration with other drugs. In this review, we will discuss the clinical occurrence of drug-induced LQTS in the context of these modifying factors as well as the mechanisms by which they contribute to altered hERG potency and proarrhythmic risk.
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8
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Sanchez de la Nava AM, Arenal Á, Fernández-Avilés F, Atienza F. Artificial Intelligence-Driven Algorithm for Drug Effect Prediction on Atrial Fibrillation: An in silico Population of Models Approach. Front Physiol 2021; 12:768468. [PMID: 34938202 PMCID: PMC8685526 DOI: 10.3389/fphys.2021.768468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/27/2021] [Indexed: 12/12/2022] Open
Abstract
Background: Antiarrhythmic drugs are the first-line treatment for atrial fibrillation (AF), but their effect is highly dependent on the characteristics of the patient. Moreover, anatomical variability, and specifically atrial size, have also a strong influence on AF recurrence. Objective: We performed a proof-of-concept study using artificial intelligence (AI) that enabled us to identify proarrhythmic profiles based on pattern identification from in silico simulations. Methods: A population of models consisting of 127 electrophysiological profiles with a variation of nine electrophysiological variables (G Na , I NaK , G K1, G CaL , G Kur , I KCa , [Na] ext , and [K] ext and diffusion) was simulated using the Koivumaki atrial model on square planes corresponding to a normal (16 cm2) and dilated (22.5 cm2) atrium. The simple pore channel equation was used for drug implementation including three drugs (isoproterenol, flecainide, and verapamil). We analyzed the effect of every ionic channel combination to evaluate arrhythmia induction. A Random Forest algorithm was trained using the population of models and AF inducibility as input and output, respectively. The algorithm was trained with 80% of the data (N = 832) and 20% of the data was used for testing with a k-fold cross-validation (k = 5). Results: We found two electrophysiological patterns derived from the AI algorithm that was associated with proarrhythmic behavior in most of the profiles, where G K1 was identified as the most important current for classifying the proarrhythmicity of a given profile. Additionally, we found different effects of the drugs depending on the electrophysiological profile and a higher tendency of the dilated tissue to fibrillate (Small tissue: 80 profiles vs Dilated tissue: 87 profiles). Conclusion: Artificial intelligence algorithms appear as a novel tool for electrophysiological pattern identification and analysis of the effect of antiarrhythmic drugs on a heterogeneous population of patients with AF.
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Affiliation(s)
- Ana Maria Sanchez de la Nava
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,ITACA Institute, Universitat Politécnica de València, València, Spain
| | - Ángel Arenal
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Francisco Fernández-Avilés
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Felipe Atienza
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
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9
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Robinson VM, Alsalahat I, Freeman S, Antzelevitch C, Barajas-Martinez H, Venetucci L. A Carvedilol Analogue, VK-II-86, Prevents Hypokalaemia-induced Ventricular Arrhythmia through Novel multi-Channel Effects. Br J Pharmacol 2021; 179:2713-2732. [PMID: 34877651 DOI: 10.1111/bph.15775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 11/07/2021] [Accepted: 11/23/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE QT prolongation and intracellular Ca2+ loading with diastolic Ca2+ release via ryanodine receptors (RyR2) are the predominant mechanisms underlying hypokalaemia-induced ventricular arrhythmia. We investigated the antiarrhythmic actions of two RyR2 inhibitors: dantrolene and VK-II-86, a carvedilol analogue with no β-blocking activity, in hypokalaemia. EXPERIMENTAL APPROACH Surface ECG and ventricular action potentials (APs) were recorded from whole-heart murine Langendorff preparations. Ventricular arrhythmia incidence was compared in hearts perfused with low [K+ ], and those pre-treated with dantrolene or VK-II-86. Whole-cell patch clamping was used in murine and canine ventricular cardiomyocytes to study the effects of dantrolene and VK-II-86 on AP parameters in low [K+ ] and the effects of VK-II-86 on the inward rectifier current (IK1 ), late sodium current (INa_L ) and the L-type Ca2+ current (ICa ). Effects of VK-II-86 on IKr were investigated in transfected HEK-293 cells. A fluorogenic probe quantified the effects of VK-II-86 on oxidative stress in hypokalaemia. KEY RESULTS Dantrolene reduced the incidence of ventricular arrhythmias induced by low [K+ ] in explanted murine hearts by 94%, whereas VK-II-86 prevented all arrhythmias. VK-II-86 prevented hypokalaemia-induced AP prolongation and depolarization, but did not alter AP parameters in normokalaemia. Hypokalaemia was associated with a significant reduction of IK1 and IKr , and increase in INa-L , and ICa . VK-II-86 prevented all hypokalaemia-induced changes in ion channel activity and oxidative stress. CONCLUSIONS AND IMPLICATIONS VK-II-86 prevents hypokalaemia-induced arrhythmogenesis by normalising calcium homeostasis and repolarization reserve. VK-II-86 may provide an exciting treatment in hypokalaemia and other arrhythmias caused by delayed repolarization or Ca2+ overload.
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Affiliation(s)
- Victoria M Robinson
- The University of Manchester, UK.,Lankenau Institute for Medical Research, Wynnewood, PA, USA
| | | | | | - Charles Antzelevitch
- Lankenau Institute for Medical Research, Wynnewood, PA, USA.,Sidney Kimmel College of Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,Lankenau Heart Institute, Wynnewood, PA, USA
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10
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Gómez-Lagunas F, Carrillo E, Barriga-Montoya C. Conductance stability and Na+ interaction with Shab K+ channels under low K+ conditions. Channels (Austin) 2021; 15:648-665. [PMID: 34658293 PMCID: PMC8555546 DOI: 10.1080/19336950.2021.1993037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/24/2021] [Accepted: 10/09/2021] [Indexed: 11/23/2022] Open
Abstract
K+ ions exert a structural effect that brings stability to K+ selective pores. Thus, upon bathing Shab channels in 0 K+ solutions the ion conductance, GK, irreversibly collapses. Related to this, studies with isolated KcsA channels have suggested that there is a transition [K+] around which the pore takes one of two conformations, either the low (non-conducting) or high K+ (conducting) crystal structures. We examined this premise by looking at the K+-dependency of GK stability of Shab channels within the cell membrane environment. We found that: K+ effect on GK stability is highly asymmetrical, and that as internal K+ is replaced by Na+ GK drops in a way that suggests a transition internal [K+]. Additionally, we found that external permeant ions inhibit GK drop with a potency that differs from the global selectivity-sequence of K+ pores; the non-permeant TEA inhibited GK drop in a K+-dependent manner. Upon lowering internal [K+] we observed an influx of Na+ at negative potentials. Na+ influx was halted by physiological external [K+], which also restored GK stability. Hyperpolarized potentials afforded GK stability but, as expected, do not restore GK selectivity. For completeness, Na+ interaction with Shab was also assessed at depolarized potentials by looking at Na block followed by permeation (pore unblock) at positive potentials, in solutions approaching the 0 K+ limit. The stabilizing effect of negative potentials along with the non-parallel variation of Na+ permeability and conductance-stability herein reported, show that pore stability and selectivity, although related, are not strictly coupled.
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Affiliation(s)
- Froylán Gómez-Lagunas
- School of Medicine, Department of Physiology, National Autonomous University of Mexico (Unam), México City, México
| | - Elisa Carrillo
- School of Medicine, Department of Physiology, National Autonomous University of Mexico (Unam), México City, México
| | - Carolina Barriga-Montoya
- School of Medicine, Department of Physiology, National Autonomous University of Mexico (Unam), México City, México
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11
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Blandin CE, Gravez BJ, Hatem SN, Balse E. Remodeling of Ion Channel Trafficking and Cardiac Arrhythmias. Cells 2021; 10:cells10092417. [PMID: 34572065 PMCID: PMC8468138 DOI: 10.3390/cells10092417] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 01/08/2023] Open
Abstract
Both inherited and acquired cardiac arrhythmias are often associated with the abnormal functional expression of ion channels at the cellular level. The complex machinery that continuously traffics, anchors, organizes, and recycles ion channels at the plasma membrane of a cardiomyocyte appears to be a major source of channel dysfunction during cardiac arrhythmias. This has been well established with the discovery of mutations in the genes encoding several ion channels and ion channel partners during inherited cardiac arrhythmias. Fibrosis, altered myocyte contacts, and post-transcriptional protein changes are common factors that disorganize normal channel trafficking during acquired cardiac arrhythmias. Channel availability, described notably for hERG and KV1.5 channels, could be another potent arrhythmogenic mechanism. From this molecular knowledge on cardiac arrhythmias will emerge novel antiarrhythmic strategies.
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Affiliation(s)
- Camille E. Blandin
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Basile J. Gravez
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Stéphane N. Hatem
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- ICAN—Institute of Cardiometabolism and Nutrition, Institute of Cardiology, Pitié-Salpêtrière Hospital, Sorbonne University, F-75013 Paris, France
| | - Elise Balse
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- Correspondence:
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12
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Du Y, Wang T, Guo J, Li W, Yang T, Szendrey M, Zhang S. Kv1.5 channels are regulated by PKC-mediated endocytic degradation. J Biol Chem 2021; 296:100514. [PMID: 33676894 PMCID: PMC8050386 DOI: 10.1016/j.jbc.2021.100514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 02/28/2021] [Accepted: 03/03/2021] [Indexed: 11/28/2022] Open
Abstract
The voltage-gated potassium channel Kv1.5 plays important roles in the repolarization of atrial action potentials and regulation of the vascular tone. While the modulation of Kv1.5 function has been well studied, less is known about how the protein levels of Kv1.5 on the cell membrane are regulated. Here, through electrophysiological and biochemical analyses of Kv1.5 channels heterologously expressed in HEK293 cells and neonatal rat ventricular myocytes, as well as native Kv1.5 in human induced pluripotent stem cell (iPSC)-derived atrial cardiomyocytes, we found that activation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate (PMA, 10 nM) diminished Kv1.5 current (IKv1.5) and protein levels of Kv1.5 in the plasma membrane. Mechanistically, PKC activation led to monoubiquitination and degradation of the mature Kv1.5 proteins. Overexpression of Vps24, a protein that sorts transmembrane proteins into lysosomes via the multivesicular body (MVB) pathway, accelerated, whereas the lysosome inhibitor bafilomycin A1 completely prevented PKC-mediated Kv1.5 degradation. Kv1.5, but not Kv1.1, Kv1.2, Kv1.3, or Kv1.4, was uniquely sensitive to PMA treatment. Sequence alignments suggested that residues within the N terminus of Kv1.5 are essential for PKC-mediated Kv1.5 reduction. Using N-terminal truncation as well as site-directed mutagenesis, we identified that Thr15 is the target site for PKC that mediates endocytic degradation of Kv1.5 channels. These findings indicate that alteration of protein levels in the plasma membrane represents an important regulatory mechanism of Kv1.5 channel function under PKC activation conditions.
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Affiliation(s)
- Yuan Du
- Department of Cardiovascular Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China; Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tingzhong Wang
- Department of Cardiovascular Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China; Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Mark Szendrey
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
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13
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Szendrey M, Guo J, Li W, Yang T, Zhang S. COVID-19 Drugs Chloroquine and Hydroxychloroquine, but Not Azithromycin and Remdesivir, Block hERG Potassium Channels. J Pharmacol Exp Ther 2021; 377:265-272. [PMID: 33674391 DOI: 10.1124/jpet.120.000484] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/02/2021] [Indexed: 12/27/2022] Open
Abstract
Drug-induced long QT syndrome (LQTS) is an established cardiac side effect of a wide range of medications and represents a significant concern for drug safety. The rapidly and slowly activating delayed rectifier K+ currents, mediated by channels encoded by the human ether-a-go-go-related gene (hERG) and KCNQ1 + KCNE1, respectively, are two main currents responsible for ventricular repolarization. The common cause for drugs to induce LQTS is through impairing the hERG channel. For the recent emergence of COVID-19, caused by severe acute respiratory syndrome coronavirus 2, several drugs have been investigated as potential therapies; however, there are concerns about their QT prolongation risk. Here, we studied the effects of chloroquine, hydroxychloroquine, azithromycin, and remdesivir on hERG channels. Our results showed that although chloroquine acutely blocked hERG current (IhERG), with an IC50 of 3.0 µM, hydroxychloroquine acutely blocked IhERG 8-fold less potently, with an IC50 of 23.4 µM. Azithromycin and remdesivir did not acutely affect IhERG When these drugs were added at 10 µM to the cell culture medium for 24 hours, remdesivir increased IhERG by 2-fold, which was associated with an increased mature hERG channel expression. In addition, these four drugs did not acutely or chronically affect KCNQ1 + KCNE1 channels. Our data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns. SIGNIFICANCE STATEMENT: This work demonstrates that, among off-label potential COVID-19 treatment drugs chloroquine, hydroxychloroquine, azithromycin, and remdesivir, the former two drugs block hERG potassium channels, whereas the latter two drugs do not. All four drugs do not affect KCNQ1 + KCNE1. As hERG and KCNQ1 + KCNE1 are two main K+ channels responsible for ventricular repolarization, and most drugs that induce long QT syndrome (LQTS) do so by impairing hERG channels, these data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns.
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Affiliation(s)
- Mark Szendrey
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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14
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Tse G, Li KHC, Cheung CKY, Letsas KP, Bhardwaj A, Sawant AC, Liu T, Yan GX, Zhang H, Jeevaratnam K, Sayed N, Cheng SH, Wong WT. Arrhythmogenic Mechanisms in Hypokalaemia: Insights From Pre-clinical Models. Front Cardiovasc Med 2021; 8:620539. [PMID: 33614751 PMCID: PMC7887296 DOI: 10.3389/fcvm.2021.620539] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/13/2021] [Indexed: 12/21/2022] Open
Abstract
Potassium is the predominant intracellular cation, with its extracellular concentrations maintained between 3. 5 and 5 mM. Among the different potassium disorders, hypokalaemia is a common clinical condition that increases the risk of life-threatening ventricular arrhythmias. This review aims to consolidate pre-clinical findings on the electrophysiological mechanisms underlying hypokalaemia-induced arrhythmogenicity. Both triggers and substrates are required for the induction and maintenance of ventricular arrhythmias. Triggered activity can arise from either early afterdepolarizations (EADs) or delayed afterdepolarizations (DADs). Action potential duration (APD) prolongation can predispose to EADs, whereas intracellular Ca2+ overload can cause both EADs and DADs. Substrates on the other hand can either be static or dynamic. Static substrates include action potential triangulation, non-uniform APD prolongation, abnormal transmural repolarization gradients, reduced conduction velocity (CV), shortened effective refractory period (ERP), reduced excitation wavelength (CV × ERP) and increased critical intervals for re-excitation (APD-ERP). In contrast, dynamic substrates comprise increased amplitude of APD alternans, steeper APD restitution gradients, transient reversal of transmural repolarization gradients and impaired depolarization-repolarization coupling. The following review article will summarize the molecular mechanisms that generate these electrophysiological abnormalities and subsequent arrhythmogenesis.
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Affiliation(s)
- Gary Tse
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ka Hou Christien Li
- Faculty of Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Konstantinos P Letsas
- Second Department of Cardiology, Laboratory of Cardiac Electrophysiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Aishwarya Bhardwaj
- Division of Cardiology, Department of Internal Medicine, State University of New York at Buffalo, Buffalo, NY, United States
| | - Abhishek C Sawant
- Division of Cardiology, Department of Internal Medicine, State University of New York at Buffalo, Buffalo, NY, United States
| | - Tong Liu
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China
| | - Gan-Xin Yan
- Lankenau Institute for Medical Research and Lankenau Medical Center, Wynnewood, PA, United States
| | - Henggui Zhang
- School of Physics and Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Nazish Sayed
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States.,Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Shuk Han Cheng
- Department of Biomedical Sciences, College of Veterinary Medicine and Life Science, City University of Hong Kong, Hong Kong, China.,State Key Laboratory of Marine Pollution (SKLMP), City University of Hong Kong, Hong Kong, China.,Department of Materials Science and Engineering, College of Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Wing Tak Wong
- School of Life Sciences, Chinese University of Hong Kong, Hong Kong, China
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15
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Xiong GL, Pinkhasov A, Mangal JP, Huang H, Rado J, Gagliardi J, Demoss D, Karol D, Suo S, Lang M, Stern M, Spearman EV, Onate J, Annamalai A, Saliba Z, Heinrich T, Fiedorowicz JG. QTc monitoring in adults with medical and psychiatric comorbidities: Expert consensus from the Association of Medicine and Psychiatry. J Psychosom Res 2020; 135:110138. [PMID: 32442893 DOI: 10.1016/j.jpsychores.2020.110138] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 04/30/2020] [Accepted: 05/07/2020] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Several psychiatric medications have the potential to prolong the QTc interval and subsequently increase the risk for ventricular arrhythmias such as torsades de pointes (TdP). There is limited guidance for clinicians to balance the risks and benefits of treatments. METHODS After a review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus guidelines for ECG monitoring of the QTc interval for patients with medical and psychiatric comorbidities who are prescribed medications with the potential to prolong the QTc interval. A risk score was developed based on risk factors for QTc prolongation to guide clinical decision-making. RESULTS A baseline ECG may not be necessary for individuals at low risk for arrythmia. Those individuals with a risk score of two or more should have an ECG prior to the start of a potentially QTc-prolonging medication or be started on a lower risk agent. Antipsychotics are not equivalent in causing QTc prolongation. A consensus-based algorithm is presented for the management of those identified at high (QTc >500 msec), intermediate (males with QTc 450-499 msec or females with QTc > 470-499 msec), or low risk. CONCLUSIONS The proposed algorithm can help clinicians in determining whether ECG monitoring should be considered for a given patient. These guidelines preserve a role for clinical judgment in selection of treatments that balance the risks and benefits, which may be particularly relevant for complex patients with medical and psychiatric comorbidities. Additional studies are needed to determine whether baseline and serial ECG monitoring reduces mortality.
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Affiliation(s)
- Glen L Xiong
- Department of Psychiatry and Behavioral Sciences, University of California at Davis School of Medicine, Sacramento, CA, United States of America.
| | - Aaron Pinkhasov
- Department of Behavioral Health, NYU Winthrop Hospital, Mineola, NY, United States of America
| | - Jed P Mangal
- Department of Behavioral Health, Martin Army Community Hospital, Ft Benning, GA, United States of America
| | - Heather Huang
- Departments of Psychiatry and Internal Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - Jeffrey Rado
- Psychiatry and General Internal Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Jane Gagliardi
- Departments of Psychiatry and Behavioral Sciences, and Internal Medicine, Duke University School of Medicine, Durham, NC, United States of America
| | - Dustin Demoss
- Department of Psychiatry, University of North Texas Health Science Center, United States of America
| | - David Karol
- Department of Psychiatry and Behavioral Neuroscience, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Shannon Suo
- Department of Psychiatry and Behavioral Sciences, University of California at Davis School of Medicine, Sacramento, CA, United States of America
| | - Michael Lang
- Departments of Psychiatry and Internal Medicine, East Carolina University, Greenville, NC, United States of America
| | - Marsha Stern
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, United States of America
| | - E Vanessa Spearman
- Departments of Internal Medicine and Psychiatry, Medical College of Georgia at Augusta University Medical Center, Augusta, GA, United States of America
| | - John Onate
- Department of Psychiatry and Behavioral Sciences, University of California at Davis School of Medicine, Sacramento, CA, United States of America
| | - Aniyizhai Annamalai
- Departments of Psychiatry and Internal Medicine, Yale School of Medicine, New Haven, CT, United States of America
| | - Zeina Saliba
- Department of Psychiatry & Behavioral Sciences and Department of Emergency Medicine, The George Washington University, Washington, D.C, Department of Obstetrics & Gynecology, Virginia Commonwealth University, Richmond, VA, United States of America
| | - Thomas Heinrich
- Departments of Psychiatry and Behavioral Medicine, Family and Community Medicine, Medical College of Wisconsin, Milwaukee, WI, United States of America
| | - Jess G Fiedorowicz
- Departments of Psychiatry, Epidemiology, and Internal Medicine, University of Iowa, Iowa City, IA, United States of America
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16
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Huang Y, Alsabbagh MW. Comparative risk of cardiac arrhythmias associated with acetylcholinesterase inhibitors used in treatment of dementias - A narrative review. Pharmacol Res Perspect 2020; 8:e00622. [PMID: 32691984 PMCID: PMC7372915 DOI: 10.1002/prp2.622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/08/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
Donepezil, galantamine, and rivastigmine are the three acetylcholinesterase inhibitors (AChEIs), out of a total of only four medications prescribed in the treatment of Alzheimer's Disease (AD) and related dementias. These medications are known to be associated with bradycardia given their mechanism of action of increasing acetylcholine (ACh). However, in March 2015, donepezil was added to the CredibleMeds "known-risk" category, a list where medications have a documented risk for acquired long-QT syndrome (ALQTS) and torsades de pointes (TdP) - a malignant ventricular arrhythmia that is a different adverse event than bradycardia (and is not necessarily associated with ACh action). The purpose of this article is to review the three AChEIs, especially with regards to mechanistic differences that may explain why only donepezil poses this risk; several pharmacological mechanisms may explain why. However, from an empirical point-of-view, aside from some case-reports, only a limited number of studies have generated relevant information regarding AChEIs' and electrocardiogram findings; none have specifically compared donepezil against galantamine or rivastigmine for malignant arrhythmias such as TdP. Currently, the choice of one of the three AChEIs for treatment of AD symptoms is primarily dependent upon clinician and patient preference. However, clinicians should be aware of the potential increased risk associated with donepezil. There is a need to examine the comparative risk of malignant arrhythmias among AChEIs users in real-world practice; this may have important implications with regards to changes in AChEI prescribing patterns.
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Affiliation(s)
- Yichang Huang
- School of PharmacyFaculty of ScienceUniversity of WaterlooKitchenerCanada
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17
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Huang Y, Alsabbagh MW. Estimates of population‐based incidence of malignant arrhythmias associated with medication use—a narrative review. Fundam Clin Pharmacol 2020; 34:418-432. [DOI: 10.1111/fcp.12578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/04/2020] [Accepted: 06/08/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Yichang Huang
- School of Pharmacy Faculty of Science University of Waterloo Room 4015, 10A Victoria St. S. Kitchener ON Canada
| | - Mhd. Wasem Alsabbagh
- School of Pharmacy Faculty of Science University of Waterloo Room 3006, 10A Victoria St. S. Kitchener ON Canada
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18
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Otani N, Kurata Y, Maharani N, Kuwabara M, Ikeda N, Notsu T, Li P, Miake J, Yoshida A, Sakaguchi H, Higaki K, Nakasone N, Tsuneto M, Shirayoshi Y, Ouchi M, Ninomiya H, Yamamoto K, Anzai N, Hisatome I. Evidence for Urate Uptake Through Monocarboxylate Transporter 9 Expressed in Mammalian Cells and Its Enhancement by Heat Shock. Circ Rep 2020; 2:425-432. [PMID: 33693264 PMCID: PMC7819574 DOI: 10.1253/circrep.cr-20-0016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Background: Monocarboxylate transporter 9 (MCT9), an orphan transporter member of the solute carrier family 16 (SLC16), possibly reabsorbs uric acid in the renal tubule and has been suggested by genome-wide association studies to be involved in the development of hyperuricemia and gout. In this study we investigated the mechanisms regulating the expression of human (h) MCT9, its degradation, and physiological functions. Methods and Results: hMCT9-FLAG was stably expressed in HEK293 cells and its degradation, intracellular localization, and urate uptake activities were assessed by pulse-chase analysis, immunofluorescence, and [14C]-urate uptake experiments, respectively. hMCT9-FLAG was localized on the plasma membrane as well as in the endoplasmic reticulum and Golgi apparatus. The proteasome inhibitors MG132 and lactacystine increased levels of hMCT9-FLAG protein expression with enhanced ubiquitination, prolonged their half-life, and decreased [14C]-urate uptake. [14C]-urate uptake was increased by both heat shock (HS) and the HS protein inducer geranylgeranylacetone (GGA). Both HS and GGA restored the [14C]-urate uptake impaired by MG132. Conclusions: hMCT9 does transport urate and is degraded by a proteasome, inhibition of which reduces hMCT9 expression on the cell membrane and urate uptake. HS enhanced urate uptake through hMCT9.
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Affiliation(s)
- Naoyuki Otani
- Department of Clinical Pharmacology and Therapeutics, Oita University Faculty of Medicine Oita Japan
| | - Yasutaka Kurata
- Department of Physiology II, Kanazawa Medical University Ishikawa Japan
| | - Nani Maharani
- Department of Pharmacology and Therapy, Faculty of Medicine Diponegoro University Semarang Indonesia
| | - Masanari Kuwabara
- Intensive Care Unit and Department of Cardiology, Toranomon Hospital Tokyo Japan
| | - Nobuhito Ikeda
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Tomomi Notsu
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Peili Li
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Junichiro Miake
- Department of Pharmacology, Tottori University Faculty of Medicine Tottori Japan
| | - Akio Yoshida
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Hiromi Sakaguchi
- Department of Radiology, Tottori University Faculty of Medicine Tottori Japan
| | - Katsumi Higaki
- Division of Functional Genomics, Tottori University Research Center for Bioscience and Technology Tottori Japan
| | - Naoe Nakasone
- Department of Biological Regulation, Tottori University Faculty of Medicine Tottori Japan
| | - Motokazu Tsuneto
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Yasuaki Shirayoshi
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
| | - Motoshi Ouchi
- Department of Pharmacology and Toxicology, Dokkyo Medical University School of Medicine Tochigi Japan
| | - Haruaki Ninomiya
- Department of Biological Regulation, Tottori University Faculty of Medicine Tottori Japan
| | - Kazuhiro Yamamoto
- Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Tottori University Faculty of Medicine Tottori Japan
| | - Naohiko Anzai
- Department of Pharmacology, Chiba University Graduate School of Medicine Chiba Japan
| | - Ichiro Hisatome
- Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science Tottori Japan
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19
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Melgari D, Barbier C, Dilanian G, Rücker-Martin C, Doisne N, Coulombe A, Hatem SN, Balse E. Microtubule polymerization state and clathrin-dependent internalization regulate dynamics of cardiac potassium channel: Microtubule and clathrin control of K V1.5 channel. J Mol Cell Cardiol 2020; 144:127-139. [PMID: 32445844 DOI: 10.1016/j.yjmcc.2020.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/08/2020] [Accepted: 05/09/2020] [Indexed: 12/19/2022]
Abstract
Ion channel trafficking powerfully influences cardiac electrical activity as it regulates the number of available channels at the plasma membrane. Studies have largely focused on identifying the molecular determinants of the trafficking of the atria-specific KV1.5 channel, the molecular basis of the ultra-rapid delayed rectifier current IKur. Besides, regulated KV1.5 channel recycling upon changes in homeostatic state and mechanical constraints in native cardiomyocytes has been well documented. Here, using cutting-edge imaging in live myocytes, we investigated the dynamics of this channel in the plasma membrane. We demonstrate that the clathrin pathway is a major regulator of the functional expression of KV1.5 channels in atrial myocytes, with the microtubule network as the prominent organizer of KV1.5 transport within the membrane. Both clathrin blockade and microtubule disruption result in channel clusterization with reduced membrane mobility and internalization, whereas disassembly of the actin cytoskeleton does not. Mobile KV1.5 channels are associated with the microtubule plus-end tracking protein EB1 whereas static KV1.5 clusters are associated with stable acetylated microtubules. In human biopsies from patients in atrial fibrillation associated with atrial remodeling, drastic modifications in the trafficking balance occurs together with alteration in microtubule polymerization state resulting in modest reduced endocytosis and increased recycling. Consequently, hallmark of atrial KV1.5 dynamics within the membrane is clathrin- and microtubule- dependent. During atrial remodeling, predominance of anterograde trafficking activity over retrograde trafficking could result in accumulation ok KV1.5 channels in the plasma membrane.
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Affiliation(s)
- Dario Melgari
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France
| | - Camille Barbier
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France
| | - Gilles Dilanian
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France
| | | | - Nicolas Doisne
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France
| | - Alain Coulombe
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France
| | - Stéphane N Hatem
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France; Institut de Cardiologie, Hôpital Pitié-Salpêtrière, Paris, France
| | - Elise Balse
- INSERM UMRS1166, ICAN - Institute of CardioMetabolism and Nutrition, Sorbonne Université, Paris, France.
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20
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Tschirhart JN, Zhang S. Fentanyl-Induced Block of hERG Channels Is Exacerbated by Hypoxia, Hypokalemia, Alkalosis, and the Presence of hERG1b. Mol Pharmacol 2020; 98:508-517. [PMID: 32321735 DOI: 10.1124/mol.119.119271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/08/2020] [Indexed: 01/19/2023] Open
Abstract
Human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium current (IKr) important for repolarization of cardiac action potentials. Drug-induced disruption of hERG channel function is a main cause of acquired long QT syndrome, which can lead to ventricular arrhythmias and sudden death. Illicit fentanyl use is associated with sudden death. We have demonstrated that fentanyl blocks hERG current (IhERG) at concentrations that overlap with the upper range of postmortem blood concentrations in fentanyl-related deaths. Since fentanyl can cause respiratory depression and electrolyte imbalances, in the present study we investigated whether certain pathologic circumstances exacerbate fentanyl-induced block of IhERG Our results show that chronic hypoxia or hypokalemia additively reduced IhERG with fentanyl. As well, high pH potentiated the fentanyl-mediated block of hERG channels, with an IC50 at pH 8.4 being 7-fold lower than that at pH 7.4. Furthermore, although the full-length hERG variant, hERG1a, has been widely used to study hERG channels, coexpression with the short variant, hERG1b (which does not produce current when expressed alone), produces functional hERG1a/1b channels, which gate more closely resembling native IKr Our results showed that fentanyl blocked hERG1a/1b channels with a 3-fold greater potency than hERG1a channels. Thus, in addition to a greater susceptibility due to the presence of hERG1b in the human heart, hERG channel block by fentanyl can be exacerbated by certain conditions, such as hypoxia, hypokalemia, or alkalosis, which may increase the risk of fentanyl-induced ventricular arrhythmias and sudden death. SIGNIFICANCE STATEMENT: This work demonstrates that heterologously expressed human ether a-go-go-related gene (hERG) 1a/1b channels, which more closely resemble rapidly activating delayed rectifier potassium current in the human heart, are blocked by fentanyl with a 3-fold greater potency than the previously studied hERG1a expressed alone. Additionally, chronic hypoxia, hypokalemia, and alkalosis can increase the block of hERG current by fentanyl, potentially increasing the risk of cardiac arrhythmias and sudden death.
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Affiliation(s)
- Jared N Tschirhart
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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21
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Oshita K, Kozasa Y, Nakagawa Y, Kuwabara Y, Kuwahara K, Nakagawa T, Nakashima N, Hiraki T, Takano M. Overexpression of the HCN2 channel increases the arrhythmogenicity induced by hypokalemia. J Physiol Sci 2019; 69:653-660. [PMID: 31087220 PMCID: PMC6583697 DOI: 10.1007/s12576-019-00684-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 04/30/2019] [Indexed: 12/19/2022]
Abstract
Hypokalemia, an abnormally low level of potassium (K+), is a electrolyte imbalance that commonly occurs in heart failure patients. Hypokalemia is well known to induce lethal ventricular arrhythmia. However, the effects of hypokalemia in failing hearts that have undergone electrophysiological remodeling, i.e., the reactivation of fetal-type ion channels, remain unexplored. We have examined the effect of hypokalemia in the myocytes of transgenic mice overexpressing the hyperpolarization-activated, cyclic nucleotide-sensitive (HCN) channel in the heart (HCN2-Tg mice). Perfusion with a mild hypokalemic solution containing 3 mM K+ induced ectopic ventricular automaticity in 55.0% of HCN2-Tg mouse myocytes. In the remaining HCN2-Tg mouse myocytes, the resting membrane potential (RMP) was more depolarized than that of wild-type myocytes subjected to the same treatment and could also be hyperpolarized by an HCN channel blocker. We conclude that in hypokalemia in our mice model, the HCN2 channel was constitutively activated at the hyperpolarized RMP, thereby destabilizing the electrophysiological activity of ventricular myocytes.
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Affiliation(s)
- Kensuke Oshita
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.,Department of Anesthesiology, Kurume University School of Medicine, Kurume, Japan
| | - Yuko Kozasa
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.,Department of Anesthesiology, Kurume University School of Medicine, Kurume, Japan
| | - Yasuaki Nakagawa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yoshihiro Kuwabara
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Koichiro Kuwahara
- Department of Cardiovascular Medicine, Shinshu University School of Medicine, Matsumoto, Japan
| | - Taku Nakagawa
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan
| | - Noriyuki Nakashima
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan
| | - Teruyuki Hiraki
- Department of Anesthesiology, Kurume University School of Medicine, Kurume, Japan
| | - Makoto Takano
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.
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22
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Tsai IH, Su YJ. Thyrotoxic periodic paralysis with ventricular tachycardia. J Electrocardiol 2019; 54:93-95. [PMID: 30965211 DOI: 10.1016/j.jelectrocard.2019.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 03/23/2019] [Accepted: 04/03/2019] [Indexed: 02/07/2023]
Abstract
A 47-year-old man presented to our emergency department (ED) with limbs weakness for 2 h. His heart rate was 127 beats per minute and blood pressure was 95/49 mm Hg. He found weakness of limbs after 4-h sleep. Physical examinations revealed that the muscle strength of upper limbs is 3/5, and lower limbs are 2/5. Electrocardiogram (ECG) revealed wide QRS complex, monomorphic ventricular tachycardia (VT) with ST-segment depression and long QT interval. Serum potassium level was extremely low as 1.0 mEq/L. This led to periodic hypokalemic paralysis. Due to severe hypokalemia with possible atrioventricular block, the patient was admitted to the intensive care unit. During hospitalization, his potassium level returned to 5.1 mEq/L on the first day. He had a low level of thyroid stimulating hormone (TSH) of <0.03 micro-IU/mL (normal range: 0.25-4.00) and a high free thyroxine (T4) level of 2.43 ng/dL (normal range: 0.89-1.79 ng/dL). Therefore, hyperthyroidism was diagnosed, and 5 mg of methimazole was administered twice a day. The patient was discharged on the seventh day after admission. The final diagnosis is thyrotoxic periodic paralysis (TPP), also as known as nocturnal paralysis or night palsy.
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Affiliation(s)
- I-Hsun Tsai
- Department of Emergency Medicine, Mackay Memorial Hospital, Taipei, Taiwan
| | - Yu-Jang Su
- Department of Emergency Medicine, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medicine, Mackay Medical College, New Taipei City, Taiwan; Department of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
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23
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Mutation-specific peripheral and ER quality control of hERG channel cell-surface expression. Sci Rep 2019; 9:6066. [PMID: 30988392 PMCID: PMC6465299 DOI: 10.1038/s41598-019-42331-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 03/28/2019] [Indexed: 12/11/2022] Open
Abstract
Impaired functional plasma membrane (PM) expression of the hERG K+-channel is associated with Long-QT syndrome type-2 (LQT2) and increased risk of cardiac arrhythmia. Reduced PM-expression is primarily attributed to retention and degradation of misfolded channels by endoplasmic reticulum (ER) protein quality control (QC) systems. However, as the molecular pathogenesis of LQT2 was defined using severely-misfolded hERG variants with limited PM-expression, the potential contribution of post-ER (peripheral) QC pathways to the disease phenotype remains poorly established. Here, we investigate the cellular processing of mildly-misfolded Per-Arnt-Sim (PAS)-domain mutant hERGs, which display incomplete ER-retention and PM-expression defects at physiological temperature. We show that the attenuated PM-expression of hERG is dictated by mutation-specific contributions from both the ER and peripheral QC systems. At the ER, PAS-mutants experience inefficient conformational maturation coupled with rapid ubiquitin-dependent proteasomal degradation. In post-ER compartments, they are rapidly endocytosed from the PM via a ubiquitin-independent mechanism and rapidly targeted for lysosomal degradation. Conformational destabilization underlies aberrant cellular processing at both ER- and post-ER compartments, since conformational correction by a hERG-specific pharmacochaperone or low-temperatures can restore WT-like trafficking. Our results demonstrate that the post-ER QC alone or jointly with the ER QC determines the loss-of-PM-expression phenotype of a subset of LQT2 mutations.
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24
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Weiss JN, Qu Z, Shivkumar K. Electrophysiology of Hypokalemia and Hyperkalemia. Circ Arrhythm Electrophysiol 2019; 10:CIRCEP.116.004667. [PMID: 28314851 DOI: 10.1161/circep.116.004667] [Citation(s) in RCA: 171] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/06/2017] [Indexed: 12/26/2022]
Affiliation(s)
- James N Weiss
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA.
| | - Zhilin Qu
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Kalyanam Shivkumar
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA
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25
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Rivera‐Juárez A, Hernández‐Romero I, Puertas C, Zhang‐Wang S, Sánchez‐Álamo B, Martins R, Figuera C, Guillem MS, Climent AM, Fernández‐Avilés F, Tejedor A, Jalife J, Atienza F. Clinical Characteristics and Electrophysiological Mechanisms Underlying Brugada ECG in Patients With Severe Hyperkalemia. J Am Heart Assoc 2019; 8:e010115. [PMID: 30675825 PMCID: PMC6405573 DOI: 10.1161/jaha.118.010115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 12/07/2018] [Indexed: 12/19/2022]
Abstract
Background Several metabolic conditions can cause the Brugada ECG pattern, also called Brugada phenotype (BrPh). We aimed to define the clinical characteristics and outcome of BrPh patients and elucidate the mechanisms underlying BrPh attributed to hyperkalemia. Methods and Results We prospectively identified patients hospitalized with severe hyperkalemia and ECG diagnosis of BrPh and compared their clinical characteristics and outcome with patients with hyperkalemia but no BrPh ECG. Computer simulations investigated the roles of extracellular potassium increase, fibrosis at the right ventricular outflow tract, and epicardial/endocardial gradients in transient outward current. Over a 6-year period, 15 patients presented severe hyperkalemia with BrPh ECG that was transient and disappeared after normalization of their serum potassium. Most patients were admitted because of various severe medical conditions causing hyperkalemia. Six (40%) patients presented malignant arrhythmias and 6 died during admission. Multiple logistic regression analysis revealed that higher serum potassium levels (odds ratio, 15.8; 95% CI, 3.1-79; P=0.001) and male sex (odds ratio, 17; 95% CI, 1.05-286; P=0.045) were risk factors for developing BrPh ECG in patients with severe hyperkalemia. In simulations, hyperkalemia yielded BrPh by promoting delayed and heterogeneous right ventricular outflow tract activation attributed to elevation of resting potential, reduced availability of inward sodium channel conductance, and increased right ventricular outflow tract fibrosis. An elevated transient outward current gradient contributed to, but was not essential for, the BrPh phenotype. Conclusions In patients with severe hyperkalemia, a BrPh ECG is associated with malignant arrhythmias and all-cause mortality secondary to resting potential depolarization, reduced sodium current availability, and fibrosis at the right ventricular outflow tract.
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Affiliation(s)
- Allan Rivera‐Juárez
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
| | - Ismael Hernández‐Romero
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
- Department of Signal Theory and CommunicationsUniversidad Rey Juan CarlosMadridSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
| | - Carolina Puertas
- Department of BiochemistryHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
| | - Serena Zhang‐Wang
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
| | - Beatriz Sánchez‐Álamo
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
| | - Raphael Martins
- CHU RennesService de Cardiologie et Maladies VasculairesRennesFrance
| | - Carlos Figuera
- Department of Signal Theory and CommunicationsUniversidad Rey Juan CarlosMadridSpain
| | | | - Andreu M. Climent
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
- ITACAUniversitat Politécnica de ValenciaValenciaSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
| | - Francisco Fernández‐Avilés
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
| | - Alberto Tejedor
- Renal Physiopathology LaboratoryDepartment of NephrologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
| | - José Jalife
- Center for Arrhythmia ResearchUniversity of MichiganAnn ArborMI
- Departamento de Arritmias CardĺacasFundacion Centro Nacional de Investigaciones Cardiovasculares (CNIC)MadridSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
| | - Felipe Atienza
- Department of CardiologyHospital General Universitario Gregorio MarañónInstituto de Investigación Sanitaria Gregorio MarañónFacultad de MedicinaUniversidad ComplutenseMadridSpain
- CIBERCVCentro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadridSpain
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Tschirhart JN, Li W, Guo J, Zhang S. Blockade of the Human Ether A-Go-Go-Related Gene (hERG) Potassium Channel by Fentanyl. Mol Pharmacol 2019; 95:386-397. [PMID: 30665971 DOI: 10.1124/mol.118.114751] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/12/2019] [Indexed: 11/22/2022] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel (IKr). Drug-mediated or medical condition-mediated disruption of hERG function is the primary cause of acquired long-QT syndrome, which predisposes affected individuals to ventricular arrhythmias and sudden death. Fentanyl abuse poses a serious health concern, with abuse and death rates rising over recent years. As fentanyl has a propensity to cause sudden death, we investigated its effects on the hERG channel. The effects of norfentanyl, the main metabolite, and naloxone, an antidote used in fentanyl overdose, were also examined. Currents of hERG channels stably expressed in HEK293 cells were recorded using the whole-cell voltage-clamp method. When hERG tail currents were analyzed upon -50 mV repolarization after a 50 mV depolarization, fentanyl and naloxone blocked hERG current (IhERG) with IC50 values of 0.9 and 74.3 μM, respectively, whereas norfentanyl did not block. However, fentanyl-mediated block of IhERG was voltage dependent. When a voltage protocol that mimics a human ventricular action potential (AP) was used, fentanyl blocked IhERG with an IC50 of 0.3 μM. Furthermore, fentanyl (0.5 μM) prolonged AP duration and blocked IKr in ventricular myocytes isolated from neonatal rats. The concentrations of fentanyl used in this study were higher than seen with clinical use but overlap with postmortem overdose concentrations. Although mechanisms of fentanyl-related sudden death need further investigation, blockade of hERG channels may contribute to the death of individuals with high-concentration overdose or compromised cardiac repolarization.
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Affiliation(s)
- Jared N Tschirhart
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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27
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Abstract
Hypokalemia is one of the most common electrolyte disturbances in the clinic and it can increase the risk of life-threatening arrhythmias. Electrocardiographic characteristics associated with hypokalemia include dynamic changes in T-wave morphology, ST-segment depression, and U waves, which are often best seen in the mid-precordial leads (V2–V4). The PR interval can also be prolonged along with an increase in the amplitude of the P wave. We report a case of a patient with hypokalemia (1.31 mmol/L) who showed typical electrocardiographic characteristics of hypokalemia.
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Affiliation(s)
- Xiqiang Wang
- Arrhythmia Unit, Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Dan Han
- Arrhythmia Unit, Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Guoliang Li
- Arrhythmia Unit, Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
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28
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Heizhati M, Zhang Y, Shao L, Wang Y, Yao X, Abulikemu S, Zhang D, Chang G, Zhou L, Li N. Decreased serum potassium may disturb sleep homeostasis in essential hypertensives. Hypertens Res 2018; 42:174-181. [PMID: 30446708 PMCID: PMC8075976 DOI: 10.1038/s41440-018-0131-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 05/08/2018] [Accepted: 05/24/2018] [Indexed: 11/09/2022]
Abstract
The aim is to investigate the association between alterations in the serum potassium (K+) concentration and sleep architecture parameters in essential hypertensives. Two hundred ninety-two hypertensives undergoing polysomnography and providing blood samples were recruited. The sleep architecture was composed of sleep stages 1 (N1), 2 (N2), 3 (N3), 4 (N4) and REM. The light sleep stage (LST) was composed of N1 + N2, and the deep sleep stage (DST) was composed of N3 + N4. The potentialrelationships between electrolytes and sleep parameters were determined via univariate and multivariate analyses. The subjects were divided into two groups via the serum K+ median (3.86 mmol/L). The K+ < 3.86 mmol/L group showed significantly decreased N1 (7.10 ± 4.55% vs 8.61 ± 5.23%, p = 0.002), LST (71.48 ± 11.33% vs 75.92 ± 17.08%, p = 0.013), and periodic leg movement during sleep related to microarousals (MA) /arousal (PLMS-A) [4 (1~10) vs 8 (3~15)/night, p < 0.001] and increased REM (17.38 ± 6.43% vs 15.37 ± 6.18%, p = 0.007) compared to the K+ ≥ 3.86 mmol/L group. A subdivided analysis by gender showed that these changes were more statistically significant in men than in women. Significant positive correlations were identified between K+ and N1 (r = 0.169, p = 0.004), as well as PLMS-A (r = 0.222, p < 0.001) in subjects. Compared to women, a significantly strong correlation was identified between K+ and REM sleep in men (r = 0.158, p = 0.028 vs. r = 0.078, p = 0.442). Multiple linear regression analysis indicated that K+ is significantly associated with N1 in all subjects (p = 0.03) and with REM in men (p = 0.008), even after adjusting for confounders. Decreased K+ may disturb the homeostasis of the sleep architecture, and gender may interfere with their links in the hypertensive population.
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Affiliation(s)
- Mulalibieke Heizhati
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Yu Zhang
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Liang Shao
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Yingchun Wang
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Xiaoguang Yao
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Suofeiya Abulikemu
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Delian Zhang
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Guijuan Chang
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Ling Zhou
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China
| | - Nanfang Li
- The Center of Hypertension of People's Hospital of Xinjiang Uygur Autonomous Region China; The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang, China. No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, CN, 830001, China.
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Lamothe SM, Hogan-Cann AE, Li W, Guo J, Yang T, Tschirhart JN, Zhang S. The N terminus and transmembrane segment S1 of Kv1.5 can coassemble with the rest of the channel independently of the S1-S2 linkage. J Biol Chem 2018; 293:15347-15358. [PMID: 30121572 DOI: 10.1074/jbc.ra118.004065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/14/2018] [Indexed: 11/06/2022] Open
Abstract
The voltage-gated potassium channel Kv1.5 belongs to the Shaker superfamily. Kv1.5 is composed of four subunits, each comprising 613 amino acids, which make up the N terminus, six transmembrane segments (S1-S6), and the C terminus. We recently demonstrated that, in HEK cells, extracellularly applied proteinase K (PK) cleaves Kv1.5 channels at a single site in the S1-S2 linker. This cleavage separates Kv1.5 into an N-fragment (N terminus to S1) and a C-fragment (S2 to C terminus). Interestingly, the cleavage does not impair channel function. Here, we investigated the role of the N terminus and S1 in Kv1.5 expression and function by creating plasmids encoding various fragments, including those that mimic PK-cleaved products. Our results disclosed that although expression of the pore-containing fragment (Frag(304-613)) alone could not produce current, coexpression with Frag(1-303) generated a functional channel. Immunofluorescence and biotinylation analyses uncovered that Frag(1-303) was required for Frag(304-613) to traffic to the plasma membrane. Biochemical analysis revealed that the two fragments interacted throughout channel trafficking and maturation. In Frag(1-303)+(304-613)-coassembled channels, which lack a covalent linkage between S1 and S2, amino acid residues 1-209 were important for association with Frag(304-613), and residues 210-303 were necessary for mediating trafficking of coassembled channels to the plasma membrane. We conclude that the N terminus and S1 of Kv1.5 can attract and coassemble with the rest of the channel (i.e. Frag(304-613)) to form a functional channel independently of the S1-S2 linkage.
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Affiliation(s)
- Shawn M Lamothe
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Aja E Hogan-Cann
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Wentao Li
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Jun Guo
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Tonghua Yang
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Jared N Tschirhart
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Shetuan Zhang
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Choi SW, Choi SW, Jeon YK, Moon SH, Zhang YH, Kim SJ. Suppression of hERG K + current and cardiac action potential prolongation by 4-hydroxynonenal via dual mechanisms. Redox Biol 2018; 19:190-199. [PMID: 30172983 PMCID: PMC6122396 DOI: 10.1016/j.redox.2018.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/20/2018] [Accepted: 08/23/2018] [Indexed: 01/08/2023] Open
Abstract
Oxidative stress under pathological conditions, such as ischemia/reperfusion and inflammation, results in the production of various reactive chemicals. Of these chemicals, 4-hydroxynonenal (4-HNE), a peroxidation product of ω6-polyunsaturated fatty acid, has garnered significant attention. However, the effect of 4-HNE on cardiac electrophysiology has not yet been reported. In the present study, we investigated the effects of 4-HNE on several cardiac ion channels, including human ether-a-go-go-related (hERG) channels, using the whole-cell patch clamp technique. Short-term exposure to 100 μM 4-HNE (4-HNE100S), which mimics local levels under oxidative stress, decreased the amplitudes of rapidly activating delayed rectifier K+ current (IKr) in guinea pig ventricular myocytes (GPVMs) and HEK293T cells overexpressing hERG (IhERG). MS analysis revealed the formation of 4-HNE-hERG adduct on specific amino acid residues, including C276, K595, H70, and H687. Long-term treatment (1–3 h) with 10 μM 4-HNE (4-HNE10L), suppressed IKr and IhERG, but not IKs and ICa,L. Action potential duration (APD) of GPVMs was prolonged by 37% and 64% by 4-HNE100S and 4-HNE10L, respectively. Western blot analysis using surface biotinylation revealed a reduction in mature membrane hERG protein after treatment with 4-HNE10L. Proteasomal degradation inhibitors, such as bortezomib, prevented the 4-HNE10L-induced decrease in mature hERG, suggesting a retrograde degradation of membrane hERG due to 4-HNE. Taken together, 4-HNE100S and 4-HNE10L suppressed IhERG via functional inhibition and downregulation of membrane expression of hERG, respectively. The exposure of 4-HNE under pathological oxidative stress may increase the risk of proarrhythmic events via APD prolongation. 4-HNE-mediated hERG channel modification causes cardiac action potential prolongation. 4-HNE inhibits hERG channel by post-translational modification at Cys276, Lys595, His70, and His687. Long-term exposure to 4-HNE decreases membrane hERG channel expression.
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Affiliation(s)
- Seong Woo Choi
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Stem Cell Biology, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Si Won Choi
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Young Keul Jeon
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Sung-Hwan Moon
- Department of Stem Cell Biology, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Yin-Hua Zhang
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
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31
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Bruyneel AAN, McKeithan WL, Feyen DAM, Mercola M. Using iPSC Models to Probe Regulation of Cardiac Ion Channel Function. Curr Cardiol Rep 2018; 20:57. [DOI: 10.1007/s11886-018-1000-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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32
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Kanner SA, Jain A, Colecraft HM. Development of a High-Throughput Flow Cytometry Assay to Monitor Defective Trafficking and Rescue of Long QT2 Mutant hERG Channels. Front Physiol 2018; 9:397. [PMID: 29725305 PMCID: PMC5917007 DOI: 10.3389/fphys.2018.00397] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 04/04/2018] [Indexed: 11/24/2022] Open
Abstract
Long QT Syndrome (LQTS) is an acquired or inherited disorder characterized by prolonged QT interval, exertion-triggered arrhythmias, and sudden cardiac death. One of the most prevalent hereditary LQTS subtypes, LQT2, results from loss-of-function mutations in the hERG channel, which conducts IKr, the rapid component of the delayed rectifier K+ current, critical for cardiac repolarization. The majority of LQT2 mutations result in Class 2 deficits characterized by impaired maturation and trafficking of hERG channels. Here, we have developed a high-throughput flow cytometric assay to analyze the surface and total expression of wild-type (WT) and mutant hERG channels with single-cell resolution. To test our method, we focused on 16 LQT2 mutations in the hERG Per-Arnt-Sim (PAS) domain that were previously studied via a widely used biochemical approach that compares levels of 135-kDa immature and 155-kDa fully glycosylated hERG protein to infer surface expression. We confirmed that LQT2 mutants expressed in HEK293 cells displayed a decreased surface density compared to WT hERG, and were differentially rescued by low temperature. However, we also uncovered some notable differences from the findings obtained via the biochemical approach. In particular, three mutations (N33T, R56Q, and A57P) with apparent WT-like hERG glycosylation patterns displayed up to 50% decreased surface expression. Furthermore, despite WT-like levels of complex glycosylation, these mutants have impaired forward trafficking, and exhibit varying half-lives at the cell surface. The results highlight utility of the surface labeling/flow cytometry approach to quantitatively assess trafficking deficiencies associated with LQT2 mutations, to discern underlying mechanisms, and to report on interventions that rescue deficits in hERG surface expression.
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Affiliation(s)
- Scott A Kanner
- Doctoral Program in Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York, NY, United States
| | - Ananya Jain
- Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY, United States
| | - Henry M Colecraft
- Doctoral Program in Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York, NY, United States.,Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY, United States.,Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, NY, United States
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33
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Mackie TD, Kim BY, Subramanya AR, Bain DJ, O'Donnell AF, Welling PA, Brodsky JL. The endosomal trafficking factors CORVET and ESCRT suppress plasma membrane residence of the renal outer medullary potassium channel (ROMK). J Biol Chem 2018; 293:3201-3217. [PMID: 29311259 PMCID: PMC5836112 DOI: 10.1074/jbc.m117.819086] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 01/02/2018] [Indexed: 11/06/2022] Open
Abstract
Protein trafficking can act as the primary regulatory mechanism for ion channels with high open probabilities, such as the renal outer medullary (ROMK) channel. ROMK, also known as Kir1.1 (KCNJ1), is the major route for potassium secretion into the pro-urine and plays an indispensable role in regulating serum potassium and urinary concentrations. However, the cellular machinery that regulates ROMK trafficking has not been fully defined. To identify regulators of the cell-surface population of ROMK, we expressed a pH-insensitive version of the channel in the budding yeast Saccharomyces cerevisiae We determined that ROMK primarily resides in the endoplasmic reticulum (ER), as it does in mammalian cells, and is subject to ER-associated degradation (ERAD). However, sufficient ROMK levels on the plasma membrane rescued growth on low-potassium medium of yeast cells lacking endogenous potassium channels. Next, we aimed to identify the biological pathways most important for ROMK regulation. Therefore, we used a synthetic genetic array to identify non-essential genes that reduce the plasma membrane pool of ROMK in potassium-sensitive yeast cells. Genes identified in this screen included several members of the endosomal complexes required for transport (ESCRT) and the class-C core vacuole/endosome tethering (CORVET) complexes. Mass spectroscopy analysis confirmed that yeast cells lacking an ESCRT component accumulate higher potassium concentrations. Moreover, silencing of ESCRT and CORVET components increased ROMK levels at the plasma membrane in HEK293 cells. Our results indicate that components of the post-endocytic pathway influence the cell-surface density of ROMK and establish that components in this pathway modulate channel activity.
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Affiliation(s)
| | - Bo-Young Kim
- the Department of Physiology, University of Maryland at Baltimore, Baltimore, Maryland 21201
| | - Arohan R Subramanya
- the Departments of Medicine and Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- the Medicine and Research Services, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania 15240, and
| | - Daniel J Bain
- Geology and Environmental Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Allyson F O'Donnell
- the Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282
| | - Paul A Welling
- the Department of Physiology, University of Maryland at Baltimore, Baltimore, Maryland 21201
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Lamothe SM, Hulbert M, Guo J, Li W, Yang T, Zhang S. Glycosylation stabilizes hERG channels on the plasma membrane by decreasing proteolytic susceptibility. FASEB J 2018; 32:1933-1943. [DOI: 10.1096/fj.201700832r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/13/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Shawn M. Lamothe
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Maggie Hulbert
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Jun Guo
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Wentao Li
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Tonghua Yang
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
| | - Shetuan Zhang
- Department of Biomedical and Molecular SciencesQueen's UniversityKingstonOntarioCanada
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35
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Balse E, Boycott HE. Ion Channel Trafficking: Control of Ion Channel Density as a Target for Arrhythmias? Front Physiol 2017; 8:808. [PMID: 29089904 PMCID: PMC5650974 DOI: 10.3389/fphys.2017.00808] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022] Open
Abstract
The shape of the cardiac action potential (AP) is determined by the contributions of numerous ion channels. Any dysfunction in the proper function or expression of these ion channels can result in a change in effective refractory period (ERP) and lead to arrhythmia. The processes underlying the correct targeting of ion channels to the plasma membrane are complex, and have not been fully characterized in cardiac myocytes. Emerging evidence highlights ion channel trafficking as a potential causative factor in certain acquired and inherited arrhythmias, and therapies which target trafficking as opposed to pore block are starting to receive attention. In this review we present the current evidence for the mechanisms which underlie precise control of cardiac ion channel trafficking and targeting.
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Affiliation(s)
- Elise Balse
- Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition, Faculté de Médecine Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ. Paris VI, Inserm, UMRS 1166, Université Pierre et Marie Curie, Paris, France
| | - Hannah E. Boycott
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
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36
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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37
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Abstract
Imipenem-cilastatin and piperacillin-tazobactam are two antibiotics with broad antimicrobial coverage. Besides the many well established adverse effects of these drugs, there have been few case reports of hypokalemia. Here we present an interesting case of resistant hypokalemia caused by these drugs leading to Torsades de Pointes which has never been reported in the past. Hypokalemia resolved with discontinuation of piperacillin.
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38
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Sangoi MG, Lamothe SM, Guo J, Yang T, Li W, Avery EG, Fisher JT, Zhang S. β-Arrestin-Mediated Regulation of the Human Ether-a-go-go-Related Gene Potassium Channel. Mol Pharmacol 2017; 92:162-174. [DOI: 10.1124/mol.116.108035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 05/10/2017] [Indexed: 01/22/2023] Open
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Dyrmishi B, Olldashi T, Rista E, Fureraj T, Ylli D, Ylli A. SEVERE HYPOKALEMIA INDUCED RHABDOMYOLYSIS BY PRIMARY HYPERALDOSTERONISM COEXISTENT WITH RECURRENT BILATERAL RENAL CALCULI. ACTA ENDOCRINOLOGICA-BUCHAREST 2017; 13:228-231. [PMID: 31149179 DOI: 10.4183/aeb.2017.228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Primary Hyperaldosteronism is one of the causes of secondary hypertension. Primary Hyperaldosteronism is characterised by an increase in the production of aldosterone and the inhibition of the secretion of renin. We described here a case with rhabdomyolysis and severe hypokalemia as a cause of primary hyperaldosteronism. The creatine kinase, aldosterone were very high. Cortisol values and midnight salivary cortisol values were within normal range. The patient had been under treatment for high blood pressure for more than six years, with ARBs and calcium channel blockers. During this time the potassium values measured frequently every year were below normal range, but primary hyperaldosteronism was not suspected.
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Affiliation(s)
- B Dyrmishi
- Hygeia Hospital Tirana - Dept. of Endocrinology, Tirana, Albania
| | - T Olldashi
- Hygeia Hospital Tirana - Dept. of Surgery, Tirana, Albania
| | - E Rista
- Hygeia Hospital Tirana - Dept. of Pathology, Tirana, Albania
| | - T Fureraj
- Hygeia Hospital Tirana - Dept. of Endocrinology, Tirana, Albania
| | - D Ylli
- UHC Mother Teresa Tirana - Dept. of Endocrinology, Tirana, Albania
| | - A Ylli
- UHC Mother Teresa Tirana - Dept. of Endocrinology, Tirana, Albania
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40
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Lamothe SM, Guo J, Li W, Yang T, Zhang S. The Human Ether-a-go-go-related Gene (hERG) Potassium Channel Represents an Unusual Target for Protease-mediated Damage. J Biol Chem 2016; 291:20387-401. [PMID: 27502273 DOI: 10.1074/jbc.m116.743138] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 12/22/2022] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel (IKr), which is important for cardiac repolarization. Dysfunction of hERG causes long QT syndrome and sudden death, which occur in patients with cardiac ischemia. Cardiac ischemia is also associated with activation, up-regulation, and secretion of various proteolytic enzymes. Here, using whole-cell patch clamp and Western blotting analysis, we demonstrate that the hERG/IKr channel was selectively cleaved by the serine protease, proteinase K (PK). Using molecular biology techniques including making a chimeric channel between protease-sensitive hERG and insensitive human ether-a-go-go (hEAG), as well as application of the scorpion toxin BeKm-1, we identified that the S5-pore linker of hERG is the target domain for proteinase K cleavage. To investigate the physiological relevance of the unique susceptibility of hERG to proteases, we show that cardiac ischemia in a rabbit model was associated with a reduction in mature ERG expression and an increase in the expression of several proteases, including calpain. Using cell biology approaches, we found that calpain-1 was actively released into the extracellular milieu and cleaved hERG at the S5-pore linker. Using protease cleavage-predicting software and site-directed mutagenesis, we identified that calpain-1 cleaves hERG at position Gly-603 in the S5-pore linker of hERG. Clarification of protease-mediated damage of hERG extends our understanding of hERG regulation. Damage of hERG mediated by proteases such as calpain may contribute to ischemia-associated QT prolongation and sudden cardiac death.
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Affiliation(s)
- Shawn M Lamothe
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Jun Guo
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Wentao Li
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Tonghua Yang
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Shetuan Zhang
- From the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
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41
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Zhao Y, Wang T, Guo J, Yang T, Li W, Koichopolos J, Lamothe SM, Kang Y, Ma A, Zhang S. Febrile temperature facilitates hERG/IKr degradation through an altered K(+) dependence. Heart Rhythm 2016; 13:2004-11. [PMID: 27321242 DOI: 10.1016/j.hrthm.2016.06.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Indexed: 12/28/2022]
Abstract
BACKGROUND Dysfunction of the rapidly activating delayed rectifier K(+) channel (IKr) encoded by the human ether-à-go-go-related gene (hERG) is the primary cause of acquired long QT syndrome (LQTS). Fever has been reported to trigger LQTS in various conditions. OBJECTIVE We aim to clarify the effect and underlying mechanisms of febrile temperature on hERG expressed in HEK cells, IKr in neonatal rat ventricular myocytes, and the QT interval in rabbits. METHODS Western blot analysis was used to determine the expression of hERG channel protein in stably transfected HEK 293 cells. Immunocytochemistry was used to visualize the localization of hERG channels. The whole-cell patch clamp technique was used to record hERG K(+) current (IhERG) in hERG expressing HEK 293 cells, as well as IKr, transient outward K(+) current (Ito), and L-type Ca(2+) current (ICa) in neonatal rat ventricular myocytes. Electrocardiographic recordings were performed in an in vivo rabbit model. RESULTS Compared with culture at 37°C, culture at 40°C reduced the mature hERG expression and IhERG in an extracellular K(+) concentration-dependent manner. Point mutations that remove the K(+) dependence of hERG-S624T and F627Y-also abolished the febrile temperature-induced hERG reduction. In neonatal rat ventricular myocytes, febrile temperature prolonged the action potential duration and selectively reduced IKr in a manner similar to low K(+) culture. In an in vivo rabbit model, fever and hypokalemia synergistically prolonged the QT interval. CONCLUSION Febrile temperature facilitates the development of LQTS by expediting hERG degradation through altered K(+) dependence.
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Affiliation(s)
- Yan Zhao
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tingzhong Wang
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, China
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jennifer Koichopolos
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shawn M Lamothe
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yudi Kang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Aiqun Ma
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, China
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada,.
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42
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Abstract
Heart disease produces substantial remodeling of K(+) channels that in general promotes arrhythmia occurrence. In the case of ventricular arrhythmias, K(+) channel remodeling contributes to the arrhythmic risk and increases vulnerability to torsades de pointes with K(+) channel inhibiting drugs. Atrial K(+) channel remodeling caused by atrial fibrillation promotes arrhythmia stability and presents opportunities for the development of new drugs targeting atrial inward rectifier K(+) currents. A better understanding of K(+) channel remodeling will help clinicians to appreciate arrhythmia mechanisms and determinants in a variety of clinical situations and to better manage arrhythmia therapy in patients with heart disease.
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Affiliation(s)
- Vincent Algalarrondo
- Department of Medicine, Research Center, Montreal Heart Institute, University of Montreal, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada; Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada; Faculty of Medicine, University Duisburg-Essen, Hufelandstr. 55, Essen 45122, Germany
| | - Stanley Nattel
- Department of Medicine, Research Center, Montreal Heart Institute, University of Montreal, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada; Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada; Faculty of Medicine, University Duisburg-Essen, Hufelandstr. 55, Essen 45122, Germany.
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43
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Lazzerini PE, Yue Y, Srivastava U, Fabris F, Capecchi PL, Bertolozzi I, Bacarelli MR, Morozzi G, Acampa M, Natale M, El-Sherif N, Galeazzi M, Laghi-Pasini F, Boutjdir M. Arrhythmogenicity of Anti-Ro/SSA Antibodies in Patients With Torsades de Pointes. Circ Arrhythm Electrophysiol 2016; 9:e003419. [DOI: 10.1161/circep.115.003419] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 02/25/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Pietro Enea Lazzerini
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Yuankun Yue
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Ujala Srivastava
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Frank Fabris
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Pier Leopoldo Capecchi
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Iacopo Bertolozzi
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Maria Romana Bacarelli
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Gabriella Morozzi
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Maurizio Acampa
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Mariarita Natale
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Nabil El-Sherif
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Mauro Galeazzi
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Franco Laghi-Pasini
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
| | - Mohamed Boutjdir
- From the Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy (P.E.L., P.L.C., M.R.B., G.M, M.A., M.N., M.G., F.L.-P.); VA New York Harbor Healthcare System and Department of Medicine, Cell Biology and Pharmacology, SUNY Downstate Medical Center, NY (Y.Y., U.S, F.F., N.E.-S., M.B.); Cardiology Intensive Therapy Unit, Department of Internal Medicine, Hospital of Carrara, Carrara, Italy (I.B.); Stroke Unit, University Hospital of Siena, Siena, Italy (M.A.); and
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McCauley M, Vallabhajosyula S, Darbar D. Proarrhythmic and Torsadogenic Effects of Potassium Channel Blockers in Patients. Card Electrophysiol Clin 2016; 8:481-93. [PMID: 27261836 DOI: 10.1016/j.ccep.2016.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The most common arrhythmia requiring drug treatment is atrial fibrillation (AF), which affects 2 to 5 million Americans and continues to be a major cause of morbidity and increased mortality. Despite recent advances in catheter-based and surgical therapies, antiarrhythmic drugs continue to be the mainstay of therapy for most patients with symptomatic AF. However, many antiarrhythmics block the rapid component of the cardiac delayed rectifier potassium current (IKr) as a major mechanism of action, and marked QT prolongation and pause-dependent polymorphic ventricular tachycardia (torsades de pointes) are major class toxicities.
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Affiliation(s)
- Mark McCauley
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA
| | - Sharath Vallabhajosyula
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA
| | - Dawood Darbar
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA.
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Spadavecchia J, Movia D, Moore C, Maguire CM, Moustaoui H, Casale S, Volkov Y, Prina-Mello A. Targeted polyethylene glycol gold nanoparticles for the treatment of pancreatic cancer: from synthesis to proof-of-concept in vitro studies. Int J Nanomedicine 2016; 11:791-822. [PMID: 27013874 PMCID: PMC4777276 DOI: 10.2147/ijn.s97476] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The main objective of this study was to optimize and characterize a drug delivery carrier for doxorubicin, intended to be intravenously administered, capable of improving the therapeutic index of the chemotherapeutic agent itself, and aimed at the treatment of pancreatic cancer. In light of this goal, we report a robust one-step method for the synthesis of dicarboxylic acid-terminated polyethylene glycol (PEG)-gold nanoparticles (AuNPs) and doxorubicin-loaded PEG-AuNPs, and their further antibody targeting (anti-Kv11.1 polyclonal antibody [pAb]). In in vitro proof-of-concept studies, we evaluated the influence of the nanocarrier and of the active targeting functionality on the anti-tumor efficacy of doxorubicin, with respect to its half-maximal effective concentration (EC50) and drug-triggered changes in the cell cycle. Our results demonstrated that the therapeutic efficacy of doxorubicin was positively influenced not only by the active targeting exploited through anti-Kv11.1-pAb but also by the drug coupling with a nanometer-sized delivery system, which indeed resulted in a 30-fold decrease of doxorubicin EC50, cell cycle blockage, and drug localization in the cell nuclei. The cell internalization pathway was strongly influenced by the active targeting of the Kv11.1 subunit of the human Ether-à-go-go related gene 1 (hERG1) channel aberrantly expressed on the membrane of pancreatic cancer cells. Targeted PEG-AuNPs were translocated into the lysosomes and were associated to an increased lysosomal function in PANC-1 cells. Additionally, doxorubicin release into an aqueous environment was almost negligible after 7 days, suggesting that drug release from PEG-AuNPs was triggered by enzymatic activity. Although preliminary, data gathered from this study have considerable potential in the application of safe-by-design nano-enabled drug-delivery systems (ie, nanomedicines) for the treatment of pancreatic cancer, a disease with a poor prognosis and one of the main current burdens of today's health care bill of industrialized countries.
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Affiliation(s)
- Jolanda Spadavecchia
- Laboratoire de Réactivité de Surface, Sorbonne Universités, UPMC Univ Paris VI, Paris
- Centre National de la recherche française, UMR 7244, CSPBAT, Laboratory of Chemistry, Structures, and Properties of Biomaterials and Therapeutic Agents, Université Paris 13, Sorbonne Paris Cité, Bobigny, France
| | - Dania Movia
- AMBER Centre, CRANN Institute, Dublin, Ireland
| | - Caroline Moore
- AMBER Centre, CRANN Institute, Dublin, Ireland
- Department of Clinical Medicine, School of Medicine, Trinity College, Dublin, Ireland
| | - Ciaran Manus Maguire
- AMBER Centre, CRANN Institute, Dublin, Ireland
- Department of Clinical Medicine, School of Medicine, Trinity College, Dublin, Ireland
| | - Hanane Moustaoui
- Centre National de la recherche française, UMR 7244, CSPBAT, Laboratory of Chemistry, Structures, and Properties of Biomaterials and Therapeutic Agents, Université Paris 13, Sorbonne Paris Cité, Bobigny, France
| | - Sandra Casale
- Laboratoire de Réactivité de Surface, Sorbonne Universités, UPMC Univ Paris VI, Paris
| | - Yuri Volkov
- AMBER Centre, CRANN Institute, Dublin, Ireland
- Department of Clinical Medicine, School of Medicine, Trinity College, Dublin, Ireland
| | - Adriele Prina-Mello
- AMBER Centre, CRANN Institute, Dublin, Ireland
- Department of Clinical Medicine, School of Medicine, Trinity College, Dublin, Ireland
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46
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Hogan-Cann A, Li W, Guo J, Yang T, Zhang S. Proteolytic cleavage in the S1-S2 linker of the Kv1.5 channel does not affect channel function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1082-90. [PMID: 26874203 DOI: 10.1016/j.bbamem.2016.02.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 01/14/2016] [Accepted: 02/09/2016] [Indexed: 11/25/2022]
Abstract
Kv1.5 channels mediate the ultra-rapidly activating delayed rectifier potassium current (IKur), which is important for atrial repolarization. It has been shown that cell-surface Kv1.5 channels are sensitive to cleavage by the extracellular serine protease, proteinase K (PK). Here, we investigated the effects of extracellular proteolytic digestion on the function of Kv1.5 channels stably expressed in HEK 293 cells. Our data demonstrate that PK treatment cleaved mature membrane-bound (75kDa) Kv1.5 channels at a single locus in the S1-S2 linker, producing 42-kDa N-terminal fragments and 33-kDa C-terminal fragments. Interestingly, such PK treatment did not affect the Kv1.5 current (IKv1.5) recorded using the whole-cell patch clamp technique. Analysis of cell-surface proteins isolated using biotinylation indicated that the PK-generated N- and C-terminal fragments were both present in the plasma membrane. Co-immunoprecipitation (co-IP) experiments indicated that the N- and C-terminal fragments are no longer associated after cleavage. Furthermore, following PK digestion, the N- and C-fragments degraded at different rates. PK is frequently used as a tool to analyze cell-surface localization of membrane proteins, and cleavage of cell-surface channels has been shown to abolish channel function (e.g. hERG). Our data, for the first time, demonstrate that cleavage of cell-surface channels assessed by Western blot analysis does not necessarily correlate with an elimination of the channel activities.
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Affiliation(s)
- Andrew Hogan-Cann
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
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47
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Foo B, Williamson B, Young JC, Lukacs G, Shrier A. hERG quality control and the long QT syndrome. J Physiol 2016; 594:2469-81. [PMID: 26718903 DOI: 10.1113/jp270531] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/07/2015] [Indexed: 11/08/2022] Open
Abstract
Long-QT syndrome type-2 (LQT2) is characterized by reduced functional expression of the human ether-à-go-go related (hERG) gene product, resulting in impaired cardiac repolarization and predisposition to fatal arrhythmia. Previous studies have implicated abnormal trafficking of misfolded hERG as the primary mechanism of LQT2, with misfolding being caused by mutations in the hERG gene (inherited) or drug treatment (acquired). More generally, environmental and metabolic stresses present a constant challenge to the folding of proteins, including hERG, and must be countered by robust protein quality control (QC) systems. Disposal of partially unfolded yet functional plasma membrane (PM) proteins by protein QC contributes to the loss-of-function phenotype in various conformational diseases including cystic fibrosis (CF) and long-QT syndrome type-2 (LQT2). The prevalent view has been that the loss of PM expression of hERG is attributed to biosynthetic block by endoplasmic reticulum (ER) QC pathways. However, there is a growing appreciation for protein QC pathways acting at post-ER cellular compartments, which may contribute to conformational disease pathogenesis. This article will provide a background on the structure and cellular trafficking of hERG as well as inherited and acquired LQT2. We will review previous work on hERG ER QC and introduce the more novel view that there is a significant peripheral QC at the PM and peripheral cellular compartments. Particular attention is drawn to the unique role of the peripheral QC system in acquired LQT2. Understanding the QC process and players may provide targets for therapeutic intervention in dealing with LQT2.
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Affiliation(s)
- Brian Foo
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Brittany Williamson
- Department of Biochemistry, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Jason C Young
- Department of Biochemistry, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Gergely Lukacs
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Alvin Shrier
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
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48
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Jones DK, Liu F, Dombrowski N, Joshi S, Robertson GA. Dominant negative consequences of a hERG 1b-specific mutation associated with intrauterine fetal death. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 120:67-76. [PMID: 26772437 DOI: 10.1016/j.pbiomolbio.2016.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 12/07/2015] [Accepted: 01/04/2016] [Indexed: 12/16/2022]
Abstract
The human ether-a-go-go related gene (hERG) encodes two subunits, hERG 1a and hERG 1b, that combine in vivo to conduct the rapid delayed rectifier potassium current (IKr). Reduced IKr slows cardiac action potential (AP) repolarization and is an underlying cause of cardiac arrhythmias associated with long QT syndrome (LQTS). Although the physiological importance of hERG 1b has been elucidated, the effects of hERG 1b disease mutations on cardiac IKr and AP behavior have not been described. To explore the disease mechanism of a 1b-specific mutation associated with a case of intrauterine fetal death, we examined the effects of the 1b-R25W mutation on total protein, trafficking and membrane current levels in HEK293 cells at physiological temperatures. By all measures the 1b-R25W mutation conferred diminished expression, and exerted a temperature-sensitive, dominant-negative effect over the WT hERG 1a protein with which it was co-expressed. Membrane currents were reduced by 60% with no apparent effect on voltage dependence or deactivation kinetics. The dominant-negative effects of R25W were demonstrated in iPSC-CMs, where 1b-R25W transfection diminished native IKr compared to controls. R25W also slowed AP repolarization, and increased AP triangulation and variability in iPSC-CMs, reflecting cellular manifestations of pro-arrhythmia. These data demonstrate that R25W is a dominant-negative mutation with significant pathophysiological consequences, and provide the first direct link between hERG 1b mutation and cardiomyocyte dysfunction.
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Affiliation(s)
- David K Jones
- Dept. of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison WI 53705, USA
| | - Fang Liu
- Dept. of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison WI 53705, USA
| | - Natasha Dombrowski
- Dept. of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison WI 53705, USA
| | - Sunita Joshi
- Dept. of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison WI 53705, USA
| | - Gail A Robertson
- Dept. of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison WI 53705, USA.
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49
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Chapter Five - Ubiquitination of Ion Channels and Transporters. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:161-223. [DOI: 10.1016/bs.pmbts.2016.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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50
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Regulation of the human ether-a-go-go-related gene (hERG) potassium channel by Nedd4 family interacting proteins (Ndfips). Biochem J 2015; 472:71-82. [DOI: 10.1042/bj20141282] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 09/10/2015] [Indexed: 01/01/2023]
Abstract
The human ether-a-go-go-related gene (hERG)-encoded K+ channel is critical for cardiac repolarization. In the present study, we demonstrate that the E3 ubiquitin (Ub) ligase neural precursor cell expressed developmentally down-regulated protein 4-2 (Nedd4-2) is directed to specific cellular compartments by Nedd4 family-interacting proteins (Ndfips) to selectively target the mature hERG channels for degradation.
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