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Synková I, Bébarová M, Andršová I, Chmelikova L, Švecová O, Hošek J, Pásek M, Vít P, Valášková I, Gaillyová R, Navrátil R, Novotný T. Long-QT founder variant T309I-Kv7.1 with dominant negative pattern may predispose delayed afterdepolarizations under β-adrenergic stimulation. Sci Rep 2021; 11:3573. [PMID: 33574382 PMCID: PMC7878757 DOI: 10.1038/s41598-021-81670-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022] Open
Abstract
The variant c.926C > T (p.T309I) in KCNQ1 gene was identified in 10 putatively unrelated Czech families with long QT syndrome (LQTS). Mutation carriers (24 heterozygous individuals) were more symptomatic compared to their non-affected relatives (17 individuals). The carriers showed a mild LQTS phenotype including a longer QTc interval at rest (466 ± 24 ms vs. 418 ± 20 ms) and after exercise (508 ± 32 ms vs. 417 ± 24 ms), 4 syncopes and 2 aborted cardiac arrests. The same haplotype associated with the c.926C > T variant was identified in all probands. Using the whole cell patch clamp technique and confocal microscopy, a complete loss of channel function was revealed in the homozygous setting, caused by an impaired channel trafficking. Dominant negativity with preserved reactivity to β-adrenergic stimulation was apparent in the heterozygous setting. In simulations on a human ventricular cell model, the dysfunction resulted in delayed afterdepolarizations (DADs) and premature action potentials under β-adrenergic stimulation that could be prevented by a slight inhibition of calcium current. We conclude that the KCNQ1 variant c.926C > T is the first identified LQTS-related founder mutation in Central Europe. The dominant negative channel dysfunction may lead to DADs under β-adrenergic stimulation. Inhibition of calcium current could be possible therapeutic strategy in LQTS1 patients refractory to β-blocker therapy.
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Affiliation(s)
- Iva Synková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic
| | - Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Larisa Chmelikova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00, Brno, Czech Republic
| | - Olga Švecová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jan Hošek
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Michal Pásek
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,Institute of Thermomechanics, Czech Academy of Sciences, Dolejškova 5, 182 00, Prague, Czech Republic
| | - Pavel Vít
- Department of Paediatrics, University Hospital Brno and Faculty of Medicine, Masaryk University, Černopolní 9, 613 00, Brno, Czech Republic
| | - Iveta Valášková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Renata Gaillyová
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Rostislav Navrátil
- Repromeda, Clinic for Reproductive Medicine and Preimplantation Genetic Diagnosis, Biology Park, Studentská 812/6, 625 00, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
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Bohnen MS, Peng G, Robey SH, Terrenoire C, Iyer V, Sampson KJ, Kass RS. Molecular Pathophysiology of Congenital Long QT Syndrome. Physiol Rev 2017; 97:89-134. [PMID: 27807201 PMCID: PMC5539372 DOI: 10.1152/physrev.00008.2016] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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Zylla MM, Thomas D. Inherited Arrhythmias: Of Channels, Currents, and Swimming. Biophys J 2016; 110:1017-22. [PMID: 26958876 DOI: 10.1016/j.bpj.2016.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 12/07/2015] [Indexed: 02/06/2023] Open
Affiliation(s)
- Maura M Zylla
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany.
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Nekouzadeh A, Rudy Y. Conformational changes of an ion-channel during gating and emerging electrophysiologic properties: Application of a computational approach to cardiac Kv7.1. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:18-27. [PMID: 26743208 DOI: 10.1016/j.pbiomolbio.2015.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 12/23/2015] [Accepted: 12/28/2015] [Indexed: 10/22/2022]
Abstract
Ion channels are the "building blocks" of the excitation process in excitable tissues. Despite advances in determining their molecular structure, understanding the relationship between channel protein structure and electrical excitation remains a challenge. The Kv7.1 potassium channel is an important determinant of the cardiac action potential and its adaptation to rate changes. It is subject to beta adrenergic regulation, and many mutations in the channel protein are associated with the arrhythmic long QT syndrome. In this theoretical study, we use a novel computational approach to simulate the conformational changes that Kv7.1 undergoes during activation gating and compute the resulting electrophysiologic function in terms of single-channel and macroscopic currents. We generated all possible conformations of the S4-S5 linker that couples the S3-S4 complex (voltage sensor domain, VSD) to the pore, and all associated conformations of VSD and the pore (S6). Analysis of these conformations revealed that VSD-to-pore mechanical coupling during activation gating involves outward translation of the voltage sensor, accompanied by a translation away from the pore and clockwise twist. These motions cause pore opening by moving the S4-S5 linker upward and away from the pore, providing space for the S6 tails to move away from each other. Single channel records, computed from the simulated motion trajectories during gating, have stochastic properties similar to experimentally recorded traces. Macroscopic current through an ensemble of channels displays two key properties of Kv7.1: an initial delay of activation and fast inactivation. The simulations suggest a molecular mechanism for fast inactivation; a large twist of the VSD following its outward translation results in movement of the base of the S4-S5 linker toward the pore, eliminating open pore conformations to cause inactivation.
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Affiliation(s)
- Ali Nekouzadeh
- Cardiac Bioelectricity and Arrhythmia Center and Departments of Biomedical Engineering and Cell Biology & Physiology, Washington University in St. Louis, 290 Whitaker Hall, 1 Brooking Dr., St. Louis, MO 63130, USA.
| | - Yoram Rudy
- Cardiac Bioelectricity and Arrhythmia Center and Departments of Biomedical Engineering and Cell Biology & Physiology, Washington University in St. Louis, 290 Whitaker Hall, 1 Brooking Dr., St. Louis, MO 63130, USA.
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Kim SK, Pak HN, Park Y. Synergistic restoring effects of isoproterenol and magnesium on KCNQ1-inhibited bradycardia cell models cultured in microelectrode array. Cardiology 2014; 128:15-24. [PMID: 24514589 DOI: 10.1159/000356955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 10/24/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Bradycardia is caused by loss-of-function mutations in potassium channels that regulate phase 3 repolarization of the cardiac action potential. The purpose of this study is to monitor the effects of potassium channel (KCNQ1) inhibition and to evaluate the effects of isoproterenol (ISO) and MgSO4 in restoring sinus rhythm in atrial cells. METHODS Microelectrode array was used to analyze conduction velocity, voltage amplitude and cycle length of atrial cells (HL-1). A combination of ISO and MgSO4 was used to restore sinus rhythm in these cells. RESULTS mRNA expression levels of KCNQ1 (42.2 vs. 100%, p < 0.0001), connexin 43 (29.6 vs. 100%, p = 0.0033), atrial natriuretic peptide (31.0 vs. 100%, p = 0.0030), cardiac actin (38.2 vs. 100%, p < 0.0001) and α-myosin heavy chain (31.2 vs. 100%, p = 0.00254) were significantly lower in the KCNQ1 gene-inhibited group compared to the control group. When treated with MgSO4 (1 mM) and ISO (10 μM), conduction velocity (0.0208 ± 0.0036 vs. 0.0086 ± 0.0014 m/s, p = 0.0004) and voltage amplitude (1,210.78 ± 65.81 vs. 124.1 ± 13.30 μV, p < 0.0001) were higher, and cycle length (431.55 ± 2.05 vs. 1,015.15 ± 4.31 ms, p < 0.0001) was shorter than in the gene-inhibited group. CONCLUSION Inhibition of sinus rhythm in the bradycardia cell model was recovered by treatment with ISO and MgSO4, demonstrating the potency of combination therapy in the treatment of bradycardia.
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Affiliation(s)
- Sook Kyoung Kim
- Department of Biomedical Engineering, Medical College, Korea University, Seoul, Republic of Korea
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