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Guo S, Hudmon A, Sahoo FK, Motes MR, Tsai WC, Chen PS, Rubart M. K + currents in ventricular cardiomyocytes of p.N98S-calmodulin mutant mice. Am J Physiol Heart Circ Physiol 2025; 328:H658-H675. [PMID: 39739562 DOI: 10.1152/ajpheart.00470.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Revised: 11/26/2024] [Accepted: 12/17/2024] [Indexed: 01/02/2025]
Abstract
Missense mutations in calmodulin (CaM)-encoding genes are associated with life-threatening ventricular arrhythmia syndromes. Here, we investigated the role of cardiac K+ channel dysregulation in arrhythmogenic long QT syndrome (LQTS) using a knock-in mouse model heterozygous for a recurrent mutation (p.N98S) in the Calm1 gene (Calm1N98S/+). Single-cell patch-clamp technique and whole heart optical voltage mapping were used to assess action potentials and whole cell currents. Ventricular action potential duration (APD) at baseline was similar between genotypes. The β-adrenergic agonist isoproterenol prolonged APD in myocytes and isolated perfused hearts from Calm1N98S/+, but not wild-type (Calm1+/+), mice. Current density-voltage relationships for the small-conductance calcium-activated K+ (SK) current and the inward rectifier K+ current did not significantly differ between Calm1+/+ and Calm1N98S/+ ventricular cardiomyocytes ± isoproterenol. Peak densities of other voltage-gated K+ currents were significantly larger in Calm1N98S/+ versus Calm1+/+ cells at voltages ≥40 mV, both without and with isoproterenol. Isoproterenol reduced outward KATP currents more in Calm1N98S/+ versus Calm1+/+ myocytes. Dialysis of Calm1+/+ cardiomyocytes with exogenous wild-type or N98S-CaM protein (5 µmol/L) via the pipette, respectively, increased and eliminated SK currents. The specific SK channel inhibitor apamin did not significantly alter the APD of Calm1+/+ or Calm1N98S/+ hearts ± isoproterenol. Thus, dysregulation of SK or voltage-gated K+ channels does not contribute to the β-adrenergic-induced LQTS of Calm1N98S/+ mice, possibly because cardiomyocyte content of endogenous N98S-CaM and/or its affinity for CaM-binding domains may be too low to modulate channel properties. The larger KATP current inhibition by isoproterenol may delay Calm1N98S/+ myocyte repolarization at low intracellular [ATP].NEW & NOTEWORTHY Despite in vitro and in silico evidence implicating cardiac K+ channel dysregulation in LQTS associated with missense mutations in genes-encoding calmodulin, their effects on native cardiac K+ currents are unknown. Using a knock-in mouse model harboring the p.N98S mutation in the Calm1 gene, we found no evidence for dysregulation of major cardiac K+ channels. Although these data do not support mechanistic findings from heterologous systems, our finding impacts efforts to improve therapies for calmodulinopathies.
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Affiliation(s)
- Shuai Guo
- Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Andy Hudmon
- Borch Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana, United States
| | - Firoj K Sahoo
- Borch Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana, United States
| | - Madeline R Motes
- Borch Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana, United States
| | - Wen-Chin Tsai
- Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Peng-Sheng Chen
- Department of Cardiology, Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, California, United States
| | - Michael Rubart
- Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, United States
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2
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Kovács ZM, Horváth B, Dienes C, Óvári J, Kiss D, Hézső T, Szentandrássy N, Magyar J, Bányász T, Nánási PP. Beta-Adrenergic Activation of the Inward Rectifier K + Current Is Mediated by the CaMKII Pathway in Canine Ventricular Cardiomyocytes. Int J Mol Sci 2024; 25:11609. [PMID: 39519160 PMCID: PMC11546480 DOI: 10.3390/ijms252111609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2024] [Revised: 10/16/2024] [Accepted: 10/18/2024] [Indexed: 11/16/2024] Open
Abstract
Several ion currents in the mammalian ventricular myocardium are substantially regulated by the sympathetic nervous system via β-adrenergic receptor activation, including the slow delayed rectifier K+ current and the L-type calcium current. This study investigated the downstream mechanisms of β-adrenergic receptor stimulation by isoproterenol (ISO) on the inward rectifier (IK1) and the rapid delayed rectifier (IKr) K+ currents using action potential voltage clamp (APVC) and conventional voltage clamp techniques in isolated canine left ventricular cardiomyocytes. IK1 and IKr were dissected by 50 µM BaCl2 and 1 µM E-4031, respectively. Acute application of 10 nM ISO significantly increased IK1 under the plateau phase of the action potential (0-+20 mV) using APVC, and similar results were obtained with conventional voltage clamp. However, β-adrenergic receptor stimulation did not affect the peak current density flowing during terminal repolarization or the overall IK1 integral. The ISO-induced enhancement of IK1 was blocked by the calcium/calmodulin kinase II (CaMKII) inhibitor KN-93 (1 µM) but not by the protein kinase A inhibitor H-89 (3 µM). Neither KN-93 nor H-89 affected the IK1 density under baseline conditions (in the absence of ISO). In contrast, parameters of the IKr current were not affected by β-adrenergic receptor stimulation with ISO. These findings suggest that sympathetic activation enhances IK1 in canine left ventricular cells through the CaMKII pathway, while IKr remains unaffected under the experimental conditions used.
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Affiliation(s)
- Zsigmond Máté Kovács
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Csaba Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - József Óvári
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Dénes Kiss
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
- Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
| | - Péter Pál Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.Ó.); (D.K.); (T.H.); (N.S.); (J.M.); (T.B.); (P.P.N.)
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
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3
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Crespo-García T, Cámara-Checa A, Dago M, Rubio-Alarcón M, Rapún J, Tamargo J, Delpón E, Caballero R. Regulation of cardiac ion channels by transcription factors: Looking for new opportunities of druggable targets for the treatment of arrhythmias. Biochem Pharmacol 2022; 204:115206. [PMID: 35963339 DOI: 10.1016/j.bcp.2022.115206] [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: 06/27/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 11/29/2022]
Abstract
Cardiac electrical activity is governed by different ion channels that generate action potentials. Acquired or inherited abnormalities in the expression and/or function of ion channels usually result in electrophysiological changes that can cause cardiac arrhythmias. Transcription factors (TFs) control gene transcription by binding to specific DNA sequences adjacent to target genes. Linkage analysis, candidate-gene screening within families, and genome-wide association studies have linked rare and common genetic variants in the genes encoding TFs with genetically-determined cardiac arrhythmias. Besides its critical role in cardiac development, recent data demonstrated that they control cardiac electrical activity through the direct regulation of the expression and function of cardiac ion channels in adult hearts. This narrative review summarizes some studies showing functional data on regulation of the main human atrial and ventricular Na+, Ca2+, and K+ channels by cardiac TFs such as Pitx2c, Tbx20, Tbx5, Zfhx3, among others. The results have improved our understanding of the mechanisms regulating cardiac electrical activity and may open new avenues for therapeutic interventions in cardiac acquired or inherited arrhythmias through the identification of TFs as potential drug targets. Even though TFs have for a long time been considered as 'undruggable' targets, advances in structural biology have led to the identification of unique pockets in TFs amenable to be targeted with small-molecule drugs or peptides that are emerging as novel therapeutic drugs.
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Affiliation(s)
- T Crespo-García
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - A Cámara-Checa
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - M Dago
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - M Rubio-Alarcón
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - J Rapún
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - J Tamargo
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
| | - E Delpón
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain.
| | - R Caballero
- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
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- Department of Pharmacology and Toxicology. School of Medicine. Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón. CIBERCV, 28040 Madrid, Spain
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4
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Pujar M, Vastrad B, Kavatagimath S, Vastrad C, Kotturshetti S. Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis. Sci Rep 2022; 12:9157. [PMID: 35650387 PMCID: PMC9160069 DOI: 10.1038/s41598-022-13291-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 05/16/2022] [Indexed: 12/14/2022] Open
Abstract
Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.
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Affiliation(s)
- Madhu Pujar
- Department of Pediatrics, J J M Medical College, Davangere, Karnataka, 577004, India
| | - Basavaraj Vastrad
- Department of Pharmaceutical Chemistry, K.L.E. College of Pharmacy, Gadag, Karnataka, 582101, India
| | - Satish Kavatagimath
- Department of Pharmacognosy, K.L.E. College of Pharmacy, Belagavi, Karnataka, 590010, India
| | - Chanabasayya Vastrad
- Biostatistics and Bioinformatics, Chanabasava Nilaya, Bharthinagar, Dharwad, Karnataka, 580001, India.
| | - Shivakumar Kotturshetti
- Biostatistics and Bioinformatics, Chanabasava Nilaya, Bharthinagar, Dharwad, Karnataka, 580001, India
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5
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Le Tanno P, Folacci M, Revilloud J, Faivre L, Laurent G, Pinson L, Amedro P, Millat G, Janin A, Vivaudou M, Roux-Buisson N, Fauré J. Characterization of Loss-Of-Function KCNJ2 Mutations in Atypical Andersen Tawil Syndrome. Front Genet 2021; 12:773177. [PMID: 34899860 PMCID: PMC8655864 DOI: 10.3389/fgene.2021.773177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/03/2021] [Indexed: 12/02/2022] Open
Abstract
Andersen-Tawil Syndrome (ATS) is a rare disease defined by the association of cardiac arrhythmias, periodic paralysis and dysmorphic features, and is caused by KCNJ2 loss-of-function mutations. However, when extracardiac symptoms are atypical or absent, the patient can be diagnosed with Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), a rare arrhythmia at high risk of sudden death, mostly due to RYR2 mutations. The identification of KCNJ2 variants in CPVT suspicion is very rare but important because beta blockers, the cornerstone of CPVT therapy, could be less efficient. We report here the cases of two patients addressed for CPVT-like phenotypes. Genetic investigations led to the identification of p. Arg82Trp and p. Pro186Gln de novo variants in the KCNJ2 gene. Functional studies showed that both variants forms of Kir2.1 monomers act as dominant negative and drastically reduced the activity of the tetrameric channel. We characterize here a new pathogenic variant (p.Pro186Gln) of KCNJ2 gene and highlight the interest of accurate cardiologic evaluation and of attention to extracardiac signs to distinguish CPVT from atypical ATS, and guide therapeutic decisions. We also confirm that the KCNJ2 gene must be investigated during CPVT molecular analysis.
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Affiliation(s)
- Pauline Le Tanno
- Université Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Grenoble, France
| | - Mathilde Folacci
- CEA, CNRS, Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
| | - Jean Revilloud
- CEA, CNRS, Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
| | - Laurence Faivre
- Medical Genetics Department, Dijon Bourgogne University Hospital, François Mitterand Hospital, Dijon, France
| | - Gabriel Laurent
- Cardiology Department, Dijon Bourgogne University Hospital, François Mitterand Hospital, Dijon, France
| | - Lucile Pinson
- Medical Genetics Department, University Hospital, Montpellier, France.,Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, Montpellier, France.,Genetic Department for Rare Diseases and Personalized Medicine, Clinical Division, Montpellier, France
| | - Pascal Amedro
- Pediatric and Congenital Cardiology Department, Clinical Investigation Centre, PhyMedExp, CNRS, INSERM, University of Montpellier, University Hospital, Montpellier, France
| | - Gilles Millat
- Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Alexandre Janin
- Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Michel Vivaudou
- CEA, CNRS, Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
| | - Nathalie Roux-Buisson
- Université Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Grenoble, France
| | - Julien Fauré
- Université Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Grenoble, France
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6
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Brown KA, Anderson C, Reilly L, Sondhi K, Ge Y, Eckhardt LL. Proteomic Analysis of the Functional Inward Rectifier Potassium Channel (Kir) 2.1 Reveals Several Novel Phosphorylation Sites. Biochemistry 2021; 60:3292-3301. [PMID: 34676745 DOI: 10.1021/acs.biochem.1c00555] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Membrane proteins represent a large family of proteins that perform vital physiological roles and represent key drug targets. Despite their importance, bioanalytical methods aiming to comprehensively characterize the post-translational modification (PTM) of membrane proteins remain challenging compared to other classes of proteins in part because of their inherent low expression and hydrophobicity. The inward rectifier potassium channel (Kir) 2.1, an integral membrane protein, is critical for the maintenance of the resting membrane potential and phase-3 repolarization of the cardiac action potential in the heart. The importance of this channel to cardiac physiology is highlighted by the recognition of several sudden arrhythmic death syndromes, Andersen-Tawil and short QT syndromes, which are associated with loss or gain of function mutations in Kir2.1, often triggered by changes in the β-adrenergic tone. Therefore, understanding the PTMs of this channel (particularly β-adrenergic tone-driven phosphorylation) is important for arrhythmia prevention. Here, we developed a proteomic method, integrating both top-down (intact protein) and bottom-up (after enzymatic digestion) proteomic analyses, to characterize the PTMs of recombinant wild-type and mutant Kir2.1, successfully mapping five novel sites of phosphorylation and confirming a sixth site. Our study provides a framework for future work to assess the role of PTMs in regulating Kir2.1 functions.
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Affiliation(s)
- Kyle A Brown
- Department of Surgery, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Corey Anderson
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Kunal Sondhi
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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7
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Song J, Luo Y, Jiang Y, He J. Advances in the Molecular Genetics of Catecholaminergic Polymorphic Ventricular Tachycardia. Front Pharmacol 2021; 12:718208. [PMID: 34483927 PMCID: PMC8415552 DOI: 10.3389/fphar.2021.718208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/05/2021] [Indexed: 11/13/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia is a primary arrhythmogenic syndrome with genetic features most commonly seen in adolescents, with syncope and sudden death following exercise or agitation as the main clinical manifestations. The mechanism of its occurrence is related to the aberrant release of Ca2+ from cardiomyocytes caused by abnormal RyR2 channels or CASQ2 proteins under conditions of sympathetic excitation, thus inducing a delayed posterior exertional pole, manifested by sympathetic excitation inducing adrenaline secretion, resulting in bidirectional or polymorphic ventricular tachycardia. The mortality rate of the disease is high, but patients usually do not have organic heart disease, the clinical manifestations may not be obvious, and no significant abnormal changes in the QT interval are often observed on electrocardiography. Therefore, the disease is often easily missed and misdiagnosed. A number of genetic mutations have been linked to the development of this disease, and the mechanisms are different. In this paper, we would like to summarize the possible genes related to catecholaminergic polymorphic ventricular tachycardia in order to review the genetic tests currently performed, and to further promote the development of genetic testing techniques and deepen the research on the molecular level of this disease.
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Affiliation(s)
- Junxia Song
- Departments of Cardiology, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Yanhong Luo
- Endocrinology, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Ying Jiang
- Departments of Cardiology, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Jianfeng He
- Departments of Cardiology, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
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8
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Reilly L, Eckhardt LL. Cardiac potassium inward rectifier Kir2: Review of structure, regulation, pharmacology, and arrhythmogenesis. Heart Rhythm 2021; 18:1423-1434. [PMID: 33857643 PMCID: PMC8328935 DOI: 10.1016/j.hrthm.2021.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/23/2021] [Accepted: 04/06/2021] [Indexed: 12/17/2022]
Abstract
Potassium inward rectifier channel Kir2 is an important component of terminal cardiac repolarization and resting membrane stability. This functionality is part of balanced cardiac excitability and is a defining feature of excitable cardiac membranes. “Gain-of-function” or “loss-of-function” mutations in KCNJ2, the gene encoding Kir2.1, cause genetic sudden cardiac death syndromes, and loss of the Kir2 current IK1 is a major contributing factor to arrhythmogenesis in failing human hearts. Here we provide a contemporary review of the functional structure, physiology, and pharmacology of Kir2 channels. Beyond the structure and functional relationships, we will focus on the elements of clinically used drugs that block the channel and the implications for treatment of atrial fibrillation with IK1-blocking agents. We will also review the clinical disease entities associated with KCNJ2 mutations and the growing area of research into associated arrhythmia mechanisms. Lastly, the presence of Kir2 channels has become a tipping point for electrical maturity in induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) and highlights the significance of understanding why Kir2 in iPS-CMs is important to consider for Comprehensive In Vitro Proarrhythmia Assay and drug safety testing.
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Affiliation(s)
- Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin.
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9
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Trum M, Islam MMT, Lebek S, Baier M, Hegner P, Eaton P, Maier LS, Wagner S. Inhibition of cardiac potassium currents by oxidation-activated protein kinase A contributes to early afterdepolarizations in the heart. Am J Physiol Heart Circ Physiol 2020; 319:H1347-H1357. [PMID: 33035439 PMCID: PMC7792712 DOI: 10.1152/ajpheart.00182.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) have been shown to prolong cardiac action potential duration resulting in afterdepolarizations, the cellular basis of triggered arrhythmias. As previously shown, protein kinase A type I (PKA I) is readily activated by oxidation of its regulatory subunits. However, the relevance of this mechanism of activation for cardiac pathophysiology is still elusive. In this study, we investigated the effects of oxidation-activated PKA I on cardiac electrophysiology. Ventricular cardiomyocytes were isolated from redox-dead PKA-RI Cys17Ser knock-in (KI) and wild-type (WT) mice and exposed to H2O2 (200 µmol/L) or vehicle (Veh) solution. In WT myocytes, exposure to H2O2 significantly increased oxidation of the regulatory subunit I (RI) and thus its dimerization (threefold increase in PKA RI dimer). Whole cell current clamp and voltage clamp were used to measure cardiac action potentials (APs), transient outward potassium current (Ito) and inward rectifying potassium current (IK1), respectively. In WT myocytes, H2O2 exposure significantly prolonged AP duration due to significantly decreased Ito and IK1 resulting in frequent early afterdepolarizations (EADs). Preincubation with the PKA-specific inhibitor Rp-8-Br-cAMPS (10 µmol/L) completely abolished the H2O2-dependent decrease in Ito and IK1 in WT myocytes. Intriguingly, H2O2 exposure did not prolong AP duration, nor did it decrease Ito, and only slightly enhanced EAD frequency in KI myocytes. Treatment of WT and KI cardiomyocytes with the late INa inhibitor TTX (1 µmol/L) completely abolished EAD formation. Our results suggest that redox-activated PKA may be important for H2O2-dependent arrhythmias and could be important for the development of specific antiarrhythmic drugs.NEW & NOTEWORTHY Oxidation-activated PKA type I inhibits transient outward potassium current (Ito) and inward rectifying potassium current (IK1) and contributes to ROS-induced APD prolongation as well as generation of early afterdepolarizations in murine ventricular cardiomyocytes.
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Affiliation(s)
- M. Trum
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - M. M. T. Islam
- 2Department of Biochemistry and Molecular Biology, University of Dhaka, Bangladesh
- 3Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - S. Lebek
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - M. Baier
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - P. Hegner
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - P. Eaton
- 4The William Harvey Research Institute, Charterhouse Square, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - L. S. Maier
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - S. Wagner
- 1Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
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10
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Abstract
Andersen-Tawil syndrome (ATS) is a very rare orphan genetic multisystem channelopathy without structural heart disease (with rare exceptions). ATS type 1 is inherited in an autosomal dominant fashion and is caused by mutations in the KCNJ2 gene, which encodes the α subunit of the K+ channel protein Kir2.1 (in ≈ 50-60% of cases). ATS type 2 is in turn linked to a rare mutation in the KCNJ5-GIRK4 gene that encodes the G protein-sensitive-activated inwardly rectifying K+ channel Kir3.4 (15%), which carries the acetylcholine-induced potassium current. About 30% of cases are de novo/sporadic, suggesting that additional as-yet unidentified genes also cause the disorder. A triad of periodic muscle paralysis, repolarization changes in the electrocardiogram, and structural body changes characterize ATS. The typical muscular change is episodic flaccid muscle weakness. Prolongation of the QU/QUc intervals and normal or minimally prolonged QT/QTc intervals with a tendency to ventricular arrhythmias are typical repolarization changes. Bidirectional ventricular tachycardia is the hallmark ventricular arrhythmia, but also premature ventricular contractions, and rarely, polymorphic ventricular tachycardia of torsade de pointes type may be present. Patients with ATS have characteristic physical developmental dysmorphisms that affect the face, skull, limbs, thorax, and stature. Mild learning difficulties and a distinct neurocognitive phenotype (deficits in executive function and abstract reasoning) have been described. About 60% of affected individuals have all features of the major triad. The purpose of this review is to present historical aspects, nomenclature (observations/criticisms), epidemiology, genetics, electrocardiography, arrhythmias, electrophysiological mechanisms, diagnostic criteria/clues of periodic paralysis, prognosis, and management of ATS.
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11
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Reilly L, Alvarado FJ, Lang D, Abozeid S, Van Ert H, Spellman C, Warden J, Makielski JC, Glukhov AV, Eckhardt LL. Genetic Loss of IK1 Causes Adrenergic-Induced Phase 3 Early Afterdepolariz ations and Polymorphic and Bidirectional Ventricular Tachycardia. Circ Arrhythm Electrophysiol 2020; 13:e008638. [PMID: 32931337 PMCID: PMC7574954 DOI: 10.1161/circep.120.008638] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/23/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Arrhythmia syndromes associated with KCNJ2 mutations have been described clinically; however, little is known of the underlying arrhythmia mechanism. We create the first patient inspired KCNJ2 transgenic mouse and study effects of this mutation on cardiac function, IK1, and Ca2+ handling, to determine the underlying cellular arrhythmic pathogenesis. METHODS A cardiac-specific KCNJ2-R67Q mouse was generated and bred for heterozygosity (R67Q+/-). Echocardiography was performed at rest, under anesthesia. In vivo ECG recording and whole heart optical mapping of intact hearts was performed before and after adrenergic stimulation in wild-type (WT) littermate controls and R67Q+/- mice. IK1 measurements, action potential characterization, and intracellular Ca2+ imaging from isolated ventricular myocytes at baseline and after adrenergic stimulation were performed in WT and R67Q+/- mice. RESULTS R67Q+/- mice (n=17) showed normal cardiac function, structure, and baseline electrical activity compared with WT (n=10). Following epinephrine and caffeine, only the R67Q+/- mice had bidirectional ventricular tachycardia, ventricular tachycardia, frequent ventricular ectopy, and/or bigeminy and optical mapping demonstrated high prevalence of spontaneous and sustained ventricular arrhythmia. Both R67Q+/- (n=8) and WT myocytes (n=9) demonstrated typical n-shaped IK1IV relationship; however, following isoproterenol, max outward IK1 increased by ≈20% in WT but decreased by ≈24% in R67Q+/- (P<0.01). R67Q+/- myocytes (n=5) demonstrated prolonged action potential duration at 90% repolarization and after 10 nmol/L isoproterenol compared with WT (n=7; P<0.05). Ca2+ transient amplitude, 50% decay rate, and sarcoplasmic reticulum Ca2+ content were not different between WT (n=18) and R67Q+/- (n=16) myocytes. R67Q+/- myocytes (n=10) under adrenergic stimulation showed frequent spontaneous development of early afterdepolarizations that occurred at phase 3 of action potential repolarization. CONCLUSIONS KCNJ2 mutation R67Q+/- causes adrenergic-dependent loss of IK1 during terminal repolarization and vulnerability to phase 3 early afterdepolarizations. This model clarifies a heretofore unknown arrhythmia mechanism and extends our understanding of treatment implications for patients with KCNJ2 mutation.
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Affiliation(s)
- Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Francisco J Alvarado
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Di Lang
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Sara Abozeid
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Hannah Van Ert
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Cordell Spellman
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Jarrett Warden
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Jonathan C Makielski
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Alexey V Glukhov
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
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12
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Sigalas C, Cremer M, Winbo A, Bose SJ, Ashton JL, Bub G, Montgomery JM, Burton RAB. Combining tissue engineering and optical imaging approaches to explore interactions along the neuro-cardiac axis. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200265. [PMID: 32742694 PMCID: PMC7353978 DOI: 10.1098/rsos.200265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 05/27/2020] [Indexed: 05/05/2023]
Abstract
Interactions along the neuro-cardiac axis are being explored with regard to their involvement in cardiac diseases, including catecholaminergic polymorphic ventricular tachycardia, hypertension, atrial fibrillation, long QT syndrome and sudden death in epilepsy. Interrogation of the pathophysiology and pathogenesis of neuro-cardiac diseases in animal models present challenges resulting from species differences, phenotypic variation, developmental effects and limited availability of data relevant at both the tissue and cellular level. By contrast, tissue-engineered models containing cardiomyocytes and peripheral sympathetic and parasympathetic neurons afford characterization of cellular- and tissue-level behaviours while maintaining precise control over developmental conditions, cellular genotype and phenotype. Such approaches are uniquely suited to long-term, high-throughput characterization using optical recording techniques with the potential for increased translational benefit compared to more established techniques. Furthermore, tissue-engineered constructs provide an intermediary between whole animal/tissue experiments and in silico models. This paper reviews the advantages of tissue engineering methods of multiple cell types and optical imaging techniques for the characterization of neuro-cardiac diseases.
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Affiliation(s)
| | - Maegan Cremer
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Annika Winbo
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Department of Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand
| | - Samuel J. Bose
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Jesse L. Ashton
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Gil Bub
- Department of Physiology, McGill University, Montreal, Canada
| | | | - Rebecca A. B. Burton
- Department of Pharmacology, University of Oxford, Oxford, UK
- Author for correspondence: Rebecca A. B. Burton e-mail:
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13
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Ackerman MJ, Giudicessi JR. Time to Redefine the Natural History and Clinical Management of Type 1 Andersen-Tawil Syndrome? J Am Coll Cardiol 2020; 75:1785-1787. [PMID: 32299590 DOI: 10.1016/j.jacc.2020.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/04/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, Minnesota.
| | - John R Giudicessi
- Department of Cardiovascular Medicine (Clinician-Investigator Training Program), Mayo Clinic, Rochester, Minnesota
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14
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Kistamás K, Veress R, Horváth B, Bányász T, Nánási PP, Eisner DA. Calcium Handling Defects and Cardiac Arrhythmia Syndromes. Front Pharmacol 2020; 11:72. [PMID: 32161540 PMCID: PMC7052815 DOI: 10.3389/fphar.2020.00072] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/24/2020] [Indexed: 12/13/2022] Open
Abstract
Calcium ions (Ca2+) play a major role in the cardiac excitation-contraction coupling. Intracellular Ca2+ concentration increases during systole and falls in diastole thereby determining cardiac contraction and relaxation. Normal cardiac function also requires perfect organization of the ion currents at the cellular level to drive action potentials and to maintain action potential propagation and electrical homogeneity at the tissue level. Any imbalance in Ca2+ homeostasis of a cardiac myocyte can lead to electrical disturbances. This review aims to discuss cardiac physiology and pathophysiology from the elementary membrane processes that can cause the electrical instability of the ventricular myocytes through intracellular Ca2+ handling maladies to inherited and acquired arrhythmias. Finally, the paper will discuss the current therapeutic approaches targeting cardiac arrhythmias.
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Affiliation(s)
- Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - David A Eisner
- Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
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15
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Krasi G, Precone V, Paolacci S, Stuppia L, Nodari S, Romeo F, Perrone M, Bushati V, Dautaj A, Bertelli M. Genetics and pharmacogenetics in the diagnosis and therapy of cardiovascular diseases. ACTA BIO-MEDICA : ATENEI PARMENSIS 2019; 90:7-19. [PMID: 31577248 PMCID: PMC7233637 DOI: 10.23750/abm.v90i10-s.8748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 12/20/2022]
Abstract
Cardiovascular diseases are the main cause of death worldwide. The ability to accurately define individual susceptibility to these disorders is therefore of strategic importance. Linkage analysis and genome-wide association studies have been useful for the identification of genes related to cardiovascular diseases. The identification of variants predisposing to cardiovascular diseases contributes to the risk profile and the possibility of tailored preventive or therapeutic strategies. Molecular genetics and pharmacogenetics are playing an increasingly important role in the correct clinical management of patients. For instance, genetic testing can identify variants that influence how patients metabolize medications, making it possible to prescribe personalized, safer and more efficient treatments, reducing medical costs and improving clinical outcomes. In the near future we can expect a great increment in information and genetic testing, which should be acknowledged as a true branch of diagnostics in cardiology, like hemodynamics and electrophysiology. In this review we summarize the genetics and pharmacogenetics of the main cardiovascular diseases, showing the role played by genetic information in the identification of cardiovascular risk factors and in the diagnosis and therapy of these conditions. (www.actabiomedica.it)
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16
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Sengupta S, Rothenberg KE, Li H, Hoffman BD, Bursac N. Altering integrin engagement regulates membrane localization of K ir2.1 channels. J Cell Sci 2019; 132:jcs225383. [PMID: 31391240 PMCID: PMC6771140 DOI: 10.1242/jcs.225383] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 07/31/2019] [Indexed: 12/26/2022] Open
Abstract
How ion channels localize and distribute on the cell membrane remains incompletely understood. We show that interventions that vary cell adhesion proteins and cell size also affect the membrane current density of inward-rectifier K+ channels (Kir2.1; encoded by KCNJ2) and profoundly alter the action potential shape of excitable cells. By using micropatterning to manipulate the localization and size of focal adhesions (FAs) in single HEK293 cells engineered to stably express Kir2.1 channels or in neonatal rat cardiomyocytes, we establish a robust linear correlation between FA coverage and the amplitude of Kir2.1 current at both the local and whole-cell levels. Confocal microscopy showed that Kir2.1 channels accumulate in membrane proximal to FAs. Selective pharmacological inhibition of key mediators of protein trafficking and the spatially dependent alterations in the dynamics of Kir2.1 fluorescent recovery after photobleaching revealed that the Kir2.1 channels are transported to the cell membrane uniformly, but are preferentially internalized by endocytosis at sites that are distal from FAs. Based on these results, we propose adhesion-regulated membrane localization of ion channels as a fundamental mechanism of controlling cellular electrophysiology via mechanochemical signals, independent of the direct ion channel mechanogating.
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Affiliation(s)
- Swarnali Sengupta
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | | | - Hanjun Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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17
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Dharmawan T, Nakajima T, Ohno S, Iizuka T, Tamura S, Kaneko Y, Horie M, Kurabayashi M. Identification of a novel exon3 deletion of RYR2 in a family with catecholaminergic polymorphic ventricular tachycardia. Ann Noninvasive Electrocardiol 2019; 24:e12623. [PMID: 30615235 PMCID: PMC6850420 DOI: 10.1111/anec.12623] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 11/01/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND RYR2, encoding cardiac ryanodine receptor, is the major responsible gene for catecholaminergic polymorphic ventricular tachycardia (CPVT). Meanwhile, KCNJ2, encoding inward-rectifier potassium channel (IK1 ), can be the responsible gene for atypical CPVT. We recently encountered a family with CPVT and sought to identify a responsible gene variant. METHODS A targeted panel sequencing (TPS) was employed in the proband. Copy number variation (CNV) in RYR2 was identified by focusing on read numbers in the TPS and long-range PCR. Cascade screening was conducted by a Sanger method and long-range PCR. KCNJ2 wild-type (WT) or an identified variant was expressed in COS-1 cells, and whole-cell currents (IK1 ) were recorded using patch-clamp techniques. RESULTS A 40-year-old female experienced cardiopulmonary arrest while cycling. Her ECG showed sinus bradycardia with prominent U-waves (≥0.2 mV). She had left ventricular hypertrabeculation at apex. Exercise induced frequent polymorphic ventricular arrhythmias. Her sister died suddenly at age 35 while bouldering. Her father and paternal aunt, with prominent U-waves, received permanent pacemaker due to sinus node dysfunction. The initial TPS and cascade screening identified a KCNJ2 E118D variant in all three symptomatic patients. However, after focusing on read numbers, we identified a novel exon3 deletion of RYR2 (RYR2-exon3 deletion) in all of them. Functional analysis revealed that KCNJ2 E118D generated IK1 indistinguishable from KCNJ2 WT, even in the presence of catecholaminergic stimulation. CONCLUSIONS Focusing on the read numbers in the TPS enabled us to identify a novel CNV, RYR2-exon3 deletion, which was associated with phenotypic features of this family.
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Affiliation(s)
- Tommy Dharmawan
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Tadashi Nakajima
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Suita, Japan.,Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Takashi Iizuka
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Shuntaro Tamura
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yoshiaki Kaneko
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan.,Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Otsu, Japan
| | - Masahiko Kurabayashi
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
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18
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Jackson WF. Boosting the signal: Endothelial inward rectifier K + channels. Microcirculation 2018; 24. [PMID: 27652592 DOI: 10.1111/micc.12319] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/12/2016] [Indexed: 12/19/2022]
Abstract
Endothelial cells express a diverse array of ion channels including members of the strong inward rectifier family composed of KIR 2 subunits. These two-membrane spanning domain channels are modulated by their lipid environment, and exist in macromolecular signaling complexes with receptors, protein kinases and other ion channels. Inward rectifier K+ channel (KIR ) currents display a region of negative slope conductance at membrane potentials positive to the K+ equilibrium potential that allows outward current through the channels to be activated by membrane hyperpolarization, permitting KIR to amplify hyperpolarization induced by other K+ channels and ion transporters. Increases in extracellular K+ concentration activate KIR allowing them to sense extracellular K+ concentration and transduce this change into membrane hyperpolarization. These properties position KIR to participate in the mechanism of action of hyperpolarizing vasodilators and contribute to cell-cell conduction of hyperpolarization along the wall of microvessels. The expression of KIR in capillaries in electrically active tissues may allow KIR to sense extracellular K+ , contributing to functional hyperemia. Understanding the regulation of expression and function of microvascular endothelial KIR will improve our understanding of the control of blood flow in the microcirculation in health and disease and may provide new targets for the development of therapeutics in the future.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
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19
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Affiliation(s)
- Nhat-Tu Le
- Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX
| | - Jun-Ichi Abe
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX
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20
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Different responses to exercise between Andersen–Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia. Europace 2017; 20:1675-1682. [DOI: 10.1093/europace/eux351] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/31/2017] [Indexed: 11/15/2022] Open
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21
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Boldt LH, Parwani AS, Heinzel FR. Commercially Available Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes: Another Piece in Our Tool Box, but Not a Swiss Army Knife Yet. ACTA ACUST UNITED AC 2017; 10:CIRCGENETICS.117.001913. [PMID: 29021307 DOI: 10.1161/circgenetics.117.001913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Leif-Hendrik Boldt
- From the Department of Cardiology, Charité - Universitätsmedizin Berlin, Germany; and DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany (L.H.B., F.R.H.).
| | - Abdul S Parwani
- From the Department of Cardiology, Charité - Universitätsmedizin Berlin, Germany; and DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany (L.H.B., F.R.H.)
| | - Frank R Heinzel
- From the Department of Cardiology, Charité - Universitätsmedizin Berlin, Germany; and DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany (L.H.B., F.R.H.)
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22
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Fernández-Falgueras A, Sarquella-Brugada G, Brugada J, Brugada R, Campuzano O. Cardiac Channelopathies and Sudden Death: Recent Clinical and Genetic Advances. BIOLOGY 2017; 6:7. [PMID: 28146053 PMCID: PMC5372000 DOI: 10.3390/biology6010007] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/17/2017] [Accepted: 01/20/2017] [Indexed: 12/19/2022]
Abstract
Sudden cardiac death poses a unique challenge to clinicians because it may be the only symptom of an inherited heart condition. Indeed, inherited heart diseases can cause sudden cardiac death in older and younger individuals. Two groups of familial diseases are responsible for sudden cardiac death: cardiomyopathies (mainly hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic cardiomyopathy) and channelopathies (mainly long QT syndrome, Brugada syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). This review focuses on cardiac channelopathies, which are characterized by lethal arrhythmias in the structurally normal heart, incomplete penetrance, and variable expressivity. Arrhythmias in these diseases result from pathogenic variants in genes encoding cardiac ion channels or associated proteins. Due to a lack of gross structural changes in the heart, channelopathies are often considered as potential causes of death in otherwise unexplained forensic autopsies. The asymptomatic nature of channelopathies is cause for concern in family members who may be carrying genetic risk factors, making the identification of these genetic factors of significant clinical importance.
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Affiliation(s)
| | | | - Josep Brugada
- Arrhythmias Unit, Hospital Sant Joan de Déu, University of Barcelona, Barcelona 08950, Spain.
| | - Ramon Brugada
- Cardiovascular Genetics Center, IDIBGI, Girona 17190, Spain.
- Medical Sciences Department, School of Medicine, University of Girona, Girona 17071, Spain.
- Familial Cardiomyopathies Unit, Hospital Josep Trueta, Girona 17007, Spain.
| | - Oscar Campuzano
- Cardiovascular Genetics Center, IDIBGI, Girona 17190, Spain.
- Medical Sciences Department, School of Medicine, University of Girona, Girona 17071, Spain.
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23
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Van Ert HA, McCune EC, Orland KM, Maginot KR, Von Bergen NH, January CT, Eckhardt LL. Flecainide treats a novel KCNJ2 mutation associated with Andersen-Tawil syndrome. HeartRhythm Case Rep 2016; 3:151-154. [PMID: 28491792 PMCID: PMC5420046 DOI: 10.1016/j.hrcr.2016.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Hanora A Van Ert
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, Wisconsin
| | - Elise C McCune
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, Wisconsin
| | - Kate M Orland
- University of Wisconsin-Madison Inherited Arrhythmia Clinic, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Kathleen R Maginot
- University of Wisconsin-Madison Inherited Arrhythmia Clinic, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Nicholas H Von Bergen
- University of Wisconsin-Madison Inherited Arrhythmia Clinic, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Craig T January
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, Wisconsin.,University of Wisconsin-Madison Inherited Arrhythmia Clinic, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, Wisconsin.,University of Wisconsin-Madison Inherited Arrhythmia Clinic, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin
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Sasaki K, Makiyama T, Yoshida Y, Wuriyanghai Y, Kamakura T, Nishiuchi S, Hayano M, Harita T, Yamamoto Y, Kohjitani H, Hirose S, Chen J, Kawamura M, Ohno S, Itoh H, Takeuchi A, Matsuoka S, Miura M, Sumitomo N, Horie M, Yamanaka S, Kimura T. Patient-Specific Human Induced Pluripotent Stem Cell Model Assessed with Electrical Pacing Validates S107 as a Potential Therapeutic Agent for Catecholaminergic Polymorphic Ventricular Tachycardia. PLoS One 2016; 11:e0164795. [PMID: 27764147 PMCID: PMC5072719 DOI: 10.1371/journal.pone.0164795] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 09/30/2016] [Indexed: 12/21/2022] Open
Abstract
Introduction Human induced pluripotent stem cells (hiPSCs) offer a unique opportunity for disease modeling. However, it is not invariably successful to recapitulate the disease phenotype because of the immaturity of hiPSC-derived cardiomyocytes (hiPSC-CMs). The purpose of this study was to establish and analyze iPSC-based model of catecholaminergic polymorphic ventricular tachycardia (CPVT), which is characterized by adrenergically mediated lethal arrhythmias, more precisely using electrical pacing that could promote the development of new pharmacotherapies. Method and Results We generated hiPSCs from a 37-year-old CPVT patient and differentiated them into cardiomyocytes. Under spontaneous beating conditions, no significant difference was found in the timing irregularity of spontaneous Ca2+ transients between control- and CPVT-hiPSC-CMs. Using Ca2+ imaging at 1 Hz electrical field stimulation, isoproterenol induced an abnormal diastolic Ca2+ increase more frequently in CPVT- than in control-hiPSC-CMs (control 12% vs. CPVT 43%, p<0.05). Action potential recordings of spontaneous beating hiPSC-CMs revealed no significant difference in the frequency of delayed afterdepolarizations (DADs) between control and CPVT cells. After isoproterenol application with pacing at 1 Hz, 87.5% of CPVT-hiPSC-CMs developed DADs, compared to 30% of control-hiPSC-CMs (p<0.05). Pre-incubation with 10 μM S107, which stabilizes the closed state of the ryanodine receptor 2, significantly decreased the percentage of CPVT-hiPSC-CMs presenting DADs to 25% (p<0.05). Conclusions We recapitulated the electrophysiological features of CPVT-derived hiPSC-CMs using electrical pacing. The development of DADs in the presence of isoproterenol was significantly suppressed by S107. Our model provides a promising platform to study disease mechanisms and screen drugs.
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MESH Headings
- Action Potentials/drug effects
- Adult
- Animals
- Anti-Asthmatic Agents/chemistry
- Anti-Asthmatic Agents/pharmacology
- Anti-Asthmatic Agents/therapeutic use
- Calcium/metabolism
- Calreticulin/genetics
- Calreticulin/metabolism
- Calsequestrin/genetics
- Calsequestrin/metabolism
- Cell Differentiation/drug effects
- Cells, Cultured
- Electric Stimulation
- Fibroblasts/cytology
- Fibroblasts/metabolism
- Humans
- Induced Pluripotent Stem Cells/cytology
- Induced Pluripotent Stem Cells/metabolism
- Isoproterenol/pharmacology
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Models, Biological
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/transplantation
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/chemistry
- Ryanodine Receptor Calcium Release Channel/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Tachycardia, Ventricular/drug therapy
- Tachycardia, Ventricular/pathology
- Tachycardia, Ventricular/therapy
- Thiazepines/chemistry
- Thiazepines/pharmacology
- Thiazepines/therapeutic use
- Transplantation, Heterologous
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Affiliation(s)
- Kenichi Sasaki
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
- * E-mail: (TM); (Y. Yoshida)
| | - Yoshinori Yoshida
- Kyoto University iPS Cell Research and Application, Kyoto, Japan
- * E-mail: (TM); (Y. Yoshida)
| | - Yimin Wuriyanghai
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Tsukasa Kamakura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Suguru Nishiuchi
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Mamoru Hayano
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takeshi Harita
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yuta Yamamoto
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Hirohiko Kohjitani
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Sayako Hirose
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Jiarong Chen
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Mihoko Kawamura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masaru Miura
- Division of Cardiology, Tokyo Metropolitan Children’s Medical Center, Tokyo, Japan
| | - Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center, Saitama, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Shinya Yamanaka
- Kyoto University iPS Cell Research and Application, Kyoto, Japan
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
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25
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Gray B, Bagnall RD, Lam L, Ingles J, Turner C, Haan E, Davis A, Yang PC, Clancy CE, Sy RW, Semsarian C. A novel heterozygous mutation in cardiac calsequestrin causes autosomal dominant catecholaminergic polymorphic ventricular tachycardia. Heart Rhythm 2016; 13:1652-60. [PMID: 27157848 DOI: 10.1016/j.hrthm.2016.05.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Indexed: 01/01/2023]
Abstract
BACKGROUND Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal inherited arrhythmia syndrome characterized by adrenergically stimulated ventricular tachycardia. Mutations in the cardiac ryanodine receptor gene (RYR2) cause an autosomal dominant form of CPVT, while mutations in the cardiac calsequestrin 2 gene (CASQ2) cause an autosomal recessive form. OBJECTIVE The aim of this study was to clinically and genetically evaluate a large family with severe autosomal dominant CPVT. METHODS Clinical evaluation of family members was performed, including detailed history, physical examination, electrocardiogram, exercise stress test, and autopsy review of decedents. We performed genome-wide linkage analysis in 12 family members and exome sequencing in 2 affected family members. In silico models of mouse and rabbit myocyte electrophysiology were used to predict potential disease mechanisms. RESULTS Severe CPVT with dominant inheritance in 6 members was diagnosed in a large family with 2 sudden deaths, 2 resuscitated cardiac arrests, and multiple appropriate implantable cardioverter-defibrillator shocks. A comprehensive analysis of cardiac arrhythmia genes did not reveal a pathogenic variant. Exome sequencing identified a novel heterozygous missense variant in CASQ2 (Lys180Arg) affecting a highly conserved residue, which cosegregated with disease and was absent in unaffected family members. Genome-wide linkage analysis confirmed a single linkage peak at the CASQ2 locus (logarithm of odds ratio score 3.01; θ = 0). Computer simulations predicted that haploinsufficiency was unlikely to cause the severe CPVT phenotype and suggested a dominant negative mechanism. CONCLUSION We show for the first time that a variant in CASQ2 causes autosomal dominant CPVT. Genetic testing in dominant CPVT should include screening for heterozygous CASQ2 variants.
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Affiliation(s)
- Belinda Gray
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
| | - Richard D Bagnall
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
| | - Lien Lam
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
| | - Jodie Ingles
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
| | - Christian Turner
- Department of Cardiology, Westmead Children's Hospital, Sydney, New South Wales, Australia
| | - Eric Haan
- Adult Genetics Unit, South Australian Clinical Genetics Service, SA Pathology and School of Medicine, University of Adelaide, Adelaide, New South Wales, Australia
| | - Andrew Davis
- Department of Cardiology, The Royal Children's Hospital Melbourne, Melbourne, New South Wales, Victoria, Australia
| | - Pei-Chi Yang
- Department of Pharmacology, University of California, Davis, California, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, California, USA
| | - Raymond W Sy
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Christopher Semsarian
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia.
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26
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Maturing human pluripotent stem cell-derived cardiomyocytes in human engineered cardiac tissues. Adv Drug Deliv Rev 2016; 96:110-34. [PMID: 25956564 DOI: 10.1016/j.addr.2015.04.019] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/24/2015] [Accepted: 04/25/2015] [Indexed: 12/19/2022]
Abstract
Engineering functional human cardiac tissue that mimics the native adult morphological and functional phenotype has been a long held objective. In the last 5 years, the field of cardiac tissue engineering has transitioned from cardiac tissues derived from various animal species to the production of the first generation of human engineered cardiac tissues (hECTs), due to recent advances in human stem cell biology. Despite this progress, the hECTs generated to date remain immature relative to the native adult myocardium. In this review, we focus on the maturation challenge in the context of hECTs, the present state of the art, and future perspectives in terms of regenerative medicine, drug discovery, preclinical safety testing and pathophysiological studies.
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Sumitomo N. Current topics in catecholaminergic polymorphic ventricular tachycardia. J Arrhythm 2015; 32:344-351. [PMID: 27761157 PMCID: PMC5063269 DOI: 10.1016/j.joa.2015.09.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 09/02/2015] [Accepted: 09/07/2015] [Indexed: 10/25/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is induced by emotions or exercise in patients without organic heart disease and may be polymorphic or bidirectional in nature. The prognosis of CPVT is not good, and therefore prevention of sudden death is of utmost importance. Genetic variants of CPVT include RyR2, CASQ2, CALM2, TRD, and possibly KCNJ2 and ANK2 gene mutations. Hypotheses that suggest the causes of CPVT include weakened binding of FKBP12.6 and RyR2, a store overload-induced Ca2+ release (SOICR), unzipping of intramolecular domain interactions in RyR2, and molecular and functional abnormalities caused by mutations in the CASQ2 gene. The incidence of an RyR2 anomaly in CPVTs is about 35-79%, whereas anomalies in the CASQ2 gene account for 3-5% CPVTs. The ping-pong theory, suggesting that reciprocating delayed after depolarization induces bigeminy of the right and left bundle branches, may explain the pathogenesis of bidirectional ventricular tachycardia. Flecainide, carvedilol, left sympathetic nerve denervation, and catheter ablation of the PVC may serve as new therapeutic strategies for CPVT while gene-therapy may be applied to some types of CPVT in the future. Although, not all sudden cardiac deaths in CPVT patients are currently preventable, new medical and interventional therapies may improve CPVT prognosis.
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Affiliation(s)
- Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka-City, Saitama 350-1298, Japan
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28
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Leong IUS, Sucich J, Prosser DO, Skinner JR, Crawford JR, Higgins C, Love DR. Array comparative genomic hybridization identifies a heterozygous deletion of exon 3 of the RYR2 gene. Ups J Med Sci 2015; 120:190-7. [PMID: 25835811 PMCID: PMC4526874 DOI: 10.3109/03009734.2015.1029101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a heritable cardiac disorder characterized by life-threatening ventricular tachycardia caused by exercise or acute emotional stress. The standard diagnostic screening involves Sanger-based sequencing of 45 of the 105 translated exons of the RYR2 gene, and copy number changes of a limited number of exons that are detected using multiplex ligation-dependent probe amplification (MLPA). METHODS In the current study, a previously validated bespoke array comparative genomic hybridization (aCGH) technique was used to detect copy number changes in the RYR2 gene in a 43-year-old woman clinically diagnosed with CPVT. RESULTS The CGH array detected a 1.1 kb deletion encompassing exon 3 of the RYR2 gene. This is the first report using the aCGH technique to screen for mutations causing CPVT. CONCLUSIONS The aCGH method offers significant advantages over MLPA in genetic screening for heritable cardiac disorders.
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Affiliation(s)
- Ivone U. S. Leong
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, PO Box 110031, Auckland 1142, New Zealand
| | - Jennifer Sucich
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, PO Box 110031, Auckland 1142, New Zealand
| | - Debra O. Prosser
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, PO Box 110031, Auckland 1142, New Zealand
| | - Jonathan R. Skinner
- Greenlane Paediatric and Congenital Cardiac Service, Starship Children’s Hospital, Grafton Auckland, Private Bag 92024, New Zealand
- Cardiac Inherited Disease Group, Auckland City Hospital, Auckland, New Zealand
- Department of Child Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Jackie R. Crawford
- Greenlane Paediatric and Congenital Cardiac Service, Starship Children’s Hospital, Grafton Auckland, Private Bag 92024, New Zealand
- Cardiac Inherited Disease Group, Auckland City Hospital, Auckland, New Zealand
| | - Colleen Higgins
- School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand
| | - Donald R. Love
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, PO Box 110031, Auckland 1142, New Zealand
- Cardiac Inherited Disease Group, Auckland City Hospital, Auckland, New Zealand
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Faggioni M, van der Werf C, Knollmann BC. Sinus node dysfunction in catecholaminergic polymorphic ventricular tachycardia: risk factor and potential therapeutic target? Trends Cardiovasc Med 2014; 24:273-8. [PMID: 25112803 DOI: 10.1016/j.tcm.2014.07.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/01/2014] [Accepted: 07/03/2014] [Indexed: 01/28/2023]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited heart rhythm disorder characterized by the occurrence of potentially life-threatening polymorphic ventricular tachyarrhythmias in conditions of physical or emotional stress. The underlying cause is a dysregulation in intracellular Ca handling due to mutations in the sarcoplasmic reticulum Ca release unit. Recent experimental work suggests that sinus bradycardia, which is sometimes observed in CPVT patients, may be another primary defect caused by CPVT mutations. Herein, we review the pathophysiology of CPVT and discuss the role of sinus node dysfunction as a modulator of arrhythmia risk and potential therapeutic target.
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Affiliation(s)
- Michela Faggioni
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical School, Medical Research Building IV, Rm. 1265, 2215B Garland Ave, Nashville, TN 37232-0575; Department of Cardiology, University of Pisa, Pisa, Italy
| | - Christian van der Werf
- Heart Center, Department of Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Bjorn C Knollmann
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical School, Medical Research Building IV, Rm. 1265, 2215B Garland Ave, Nashville, TN 37232-0575.
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KCNJ2 mutation causes an adrenergic-dependent rectification abnormality with calcium sensitivity and ventricular arrhythmia. Heart Rhythm 2014; 11:885-94. [PMID: 24561538 DOI: 10.1016/j.hrthm.2014.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND KCNJ2 mutations are associated with a variety of inherited arrhythmia syndromes including catecholaminergic polymorphic ventricular tachycardia 3. OBJECTIVE To characterize the detailed cellular mechanisms of the clinically recognized KCNJ2 mutation R67Q. METHODS Kir2.1 current density was measured from COS-1 cells transiently transfected with wild-type human Kir-2.1 (WT-Kir2.1) and/or a heterozygous missense mutation in KCNJ2 (R67Q-Kir2.1) by using the whole-cell voltage clamp technique. Catecholamine activity was simulated with protein kinase A-stimulating cocktail exposure. Phosphorylation-deficient mutants, S425N-Kir2.1 and S425N-Kir2.1/R67Q-S425N-Kir2.1, were used in a separate set of experiments. HA- or Myc-Tag-WT-Kir2.1 and HA-Tag-R67Q-Kir2.1 were used for confocal imaging. RESULTS A 33-year-old woman presented with a catecholaminergic polymorphic ventricular tachycardia-like clinical phenotype and was found to have KCNJ2 missense mutation R67Q. Treatment with nadolol and flecainide resulted in the complete suppression of arrhythmias and symptom resolution. Under baseline conditions, R67Q-Kir2.1 expressed alone did not produce inward rectifier current while cells coexpressing WT-Kir2.1 and R67Q-Kir2.1 demonstrated the rectification index (RI) similar to that of WT-Kir2.1. After PKA stimulation, R67Q-Kir2.1/WT-Kir2.1 failed to increase peak outward current density; WT-Kir2.1 increased by 46% (n = 5), while R67Q-Kir2.1/WT-Kir2.1 decreased by 6% (n = 6) (P = .002). Rectification properties in R67Q-Kir2.1/WT-Kir2.1 demonstrated sensitivity to calcium with a decreased RI in the high-calcium pipette solution (RI 20.3% ± 4.1%) than in the low-calcium pipette solution (RI 36.5% ± 5.7%) (P < .05). Immunostaining of WT-Kir2.1 and R67Q-Kir2.1 individually and together showed a normal membrane expression pattern and colocalization by using the Pearson correlation coefficient. CONCLUSIONS R67Q-Kir2.1 is associated with an adrenergic-dependent clinical and cellular phenotype with rectification abnormality enhanced by increased calcium. These findings are a significant advancement of our knowledge and understanding of the phenotype-genotype relationship of arrhythmia syndromes related to KCNJ2 mutations.
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Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C. Executive Summary: HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. J Arrhythm 2014. [DOI: 10.1016/j.joa.2013.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. J Arrhythm 2014. [DOI: 10.1016/j.joa.2013.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. Heart Rhythm 2013; 10:1932-63. [DOI: 10.1016/j.hrthm.2013.05.014] [Citation(s) in RCA: 1364] [Impact Index Per Article: 113.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 12/15/2022]
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Flecainide reduces ventricular arrhythmias via a mechanism that differs from that of β-blockers in catecholaminergic polymorphic ventricular tachycardia. J Arrhythm 2013. [DOI: 10.1016/j.joa.2013.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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36
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Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C, Ackerman M, Belhassen B, Estes NAM, Fatkin D, Kalman J, Kaufman E, Kirchhof P, Schulze-Bahr E, Wolpert C, Vohra J, Refaat M, Etheridge SP, Campbell RM, Martin ET, Quek SC. Executive summary: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes. Europace 2013; 15:1389-406. [PMID: 23994779 DOI: 10.1093/europace/eut272] [Citation(s) in RCA: 418] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Silvia G Priori
- From the Maugeri Foundation IRCCS, Pavia, Italy, Department of Molecular Medicine, University of Pavia, Pavia, Italy, and New York University, New York, New York
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Current perspectives in genetic cardiovascular disorders: from basic to clinical aspects. Heart Vessels 2013; 29:129-41. [PMID: 23907713 DOI: 10.1007/s00380-013-0391-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 06/27/2013] [Indexed: 12/18/2022]
Abstract
We summarize recent advances in the clinical genetics of hypercholesterolemia, hypertrophic cardiomyopathy (HCM), and lethal arrhythmia, all of which are monogenic cardiovascular diseases being essential to understanding the heart and circulatory pathophysiology. Among the issues of hypercholesterolemia which play a pivotal role in development of vascular damages, familial hypercholesterolemia is the common genetic cardiovascular disease; in addition to identifying the gene mutation coding low-density lipoprotein receptor, lipid kinetics in autosomal recessive hypercholesterolemia as well as in proprotein convertase subtilisin/kexin 9 gene mutation were recently demonstrated. As for HCM, some gene mutations were identified to correlate with clinical manifestations. Additionally, a gene polymorphism of the renin-angiotensin system in development of heart failure was identified as a modifier gene. The lethal arrhythmias such as sudden death syndromes, QT prolongation, and Brugada syndrome were found to exhibit gene mutation coding potassium and/or sodium ion channels. Interestingly, functional analysis of these gene mutations helped to identify the role of each gene mutation in developing these cardiovascular disorders. We suggest considering the genetic mechanisms of cardiovascular diseases associated with hyperlipidemia, myocardial hypertrophy, or lethal arrhythmia in terms of not only clinical diagnosis but also understanding pathophysiology of each disease with therapeutic aspects.
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Executive summary: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes. Heart Rhythm 2013; 10:e85-108. [PMID: 23916535 DOI: 10.1016/j.hrthm.2013.07.021] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 02/07/2023]
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Hsiao PY, Tien HC, Lo CP, Juang JMJ, Wang YH, Sung RJ. Gene mutations in cardiac arrhythmias: a review of recent evidence in ion channelopathies. APPLICATION OF CLINICAL GENETICS 2013; 6:1-13. [PMID: 23837003 PMCID: PMC3699290 DOI: 10.2147/tacg.s29676] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Over the past 15 years, molecular genetic studies have linked gene mutations to many inherited arrhythmogenic disorders, in particular, “ion channelopathies”, in which mutations in genes encode functional units of ion channels and/or their transporter-associated proteins in patients without primary cardiac structural abnormalities. These disorders are exemplified by congenital long QT syndrome (LQTS), short QT syndrome, Brugada syndrome (BrS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). Functional and pathophysiological studies have led to better understanding of the clinical spectrum, ion channel structures and cellular electrophysiology involving dynamics of intracellular calcium cycling in many subtypes of these disorders and more importantly, development of potentially more effective pharmacological agents and even curative gene therapy. In this review, we have summarized (1) the significance of unveiling mutations in genes encoding transporter-associated proteins as the cause of congenital LQTS, (2) the technique of catheter ablation applied at the right ventricular outflow tract may be curative for severely symptomatic BrS, (3) mutations with channel function modulated by protein Kinase A-dependent phosphorylation can be the culprit of CPVT mimicry in Andersen-Tawil syndrome (LQT7), (4) ablation of the ion channel anchoring protein may prevent arrhythmogenesis in Timothy syndrome (LQT8), (5) altered intracellular Ca2+ cycling can be the basis of effective targeted pharmacotherapy in CPVT, and (6) the technology of induced pluripotent stem cells is a promising diagnostic and research tool as it has become a new paradigm for pathophysiological study of patient- and disease-specific cells aimed at screening new drugs and eventual clinical application of gene therapy. Lastly, we have discussed (7) genotype-phenotype correlation in relation to risk stratification of patients with congenital LQTS in clinical practice.
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Affiliation(s)
- Pi-Yin Hsiao
- Institute of Life Sciences, National Central University, Taoyuan, Taiwan
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40
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Kawamura M, Ohno S, Naiki N, Nagaoka I, Dochi K, Wang Q, Hasegawa K, Kimura H, Miyamoto A, Mizusawa Y, Itoh H, Makiyama T, Sumitomo N, Ushinohama H, Oyama K, Murakoshi N, Aonuma K, Horigome H, Honda T, Yoshinaga M, Ito M, Horie M. Genetic Background of Catecholaminergic Polymorphic Ventricular Tachycardia in Japan. Circ J 2013; 77:1705-13. [DOI: 10.1253/circj.cj-12-1460] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mihoko Kawamura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Nobu Naiki
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Iori Nagaoka
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Kenichi Dochi
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Qi Wang
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Kanae Hasegawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Hiromi Kimura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Akashi Miyamoto
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Yuka Mizusawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
| | - Naokata Sumitomo
- Department of Pediatrics and Child Health, Nihon University School of Medicine
| | - Hiroya Ushinohama
- Department of Pediatric Cardiology, Fukuoka Children’s Hospital and Medical Center for Infectious Disease
| | - Kotaro Oyama
- Department of Pediatric Cardiology, Iwate Medical University Memorial Heart Center
| | - Nobuyuki Murakoshi
- Cardiovascular Division, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Kazutaka Aonuma
- Cardiovascular Division, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | | | - Takafumi Honda
- Department of Pediatrics, Tokyo Women’s Medical University Yachiyo Medical Center
| | - Masao Yoshinaga
- Department of Pediatrics, National Hospital Organization Kagoshima Medical Center
| | - Makoto Ito
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
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41
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Inhibiting the clathrin-mediated endocytosis pathway rescues KIR2.1 downregulation by pentamidine. Pflugers Arch 2012. [DOI: 10.1007/s00424-012-1189-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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42
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Kimura H, Zhou J, Kawamura M, Itoh H, Mizusawa Y, Ding WG, Wu J, Ohno S, Makiyama T, Miyamoto A, Naiki N, Wang Q, Xie Y, Suzuki T, Tateno S, Nakamura Y, Zang WJ, Ito M, Matsuura H, Horie M. Phenotype variability in patients carrying KCNJ2 mutations. ACTA ACUST UNITED AC 2012; 5:344-53. [PMID: 22589293 DOI: 10.1161/circgenetics.111.962316] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations of KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1, cause Andersen-Tawil syndrome (ATS), a disease exhibiting ventricular arrhythmia, periodic paralysis, and dysmorphic features. However, some KCNJ2 mutation carriers lack the ATS triad and sometimes share the phenotype of catecholaminergic polymorphic ventricular tachycardia (CPVT). We investigated clinical and biophysical characteristics of KCNJ2 mutation carriers with "atypical ATS." METHODS AND RESULTS Mutational analyses of KCNJ2 were performed in 57 unrelated probands showing typical (≥2 ATS features) and atypical (only 1 of the ATS features or CPVT) ATS. We identified 24 mutation carriers. Mutation-positive rates were 75% (15/20) in typical ATS, 71% (5/7) in cardiac phenotype alone, 100% (2/2) in periodic paralysis, and 7% (2/28) in CPVT. We divided all carriers (n=45, including family members) into 2 groups: typical ATS (A) (n=21, 47%) and atypical phenotype (B) (n=24, 53%). Patients in (A) had a longer QUc interval [(A): 695 ± 52 versus (B): 643 ± 35 ms] and higher U-wave amplitude (0.24 ± 0.07 versus 0.18 ± 0.08 mV). C-terminal mutations were more frequent in (A) (85% versus 38%, P<0.05). There were no significant differences in incidences of ventricular tachyarrhythmias. Functional analyses of 4 mutations found in (B) revealed that R82Q, R82W, and G144D exerted strong dominant negative suppression (current reduction by 95%, 97%, and 96%, respectively, versus WT at -50 mV) and T305S moderate suppression (reduction by 89%). CONCLUSIONS KCNJ2 gene screening in atypical ATS phenotypes is of clinical importance because more than half of mutation carriers express atypical phenotypes, despite their arrhythmia severity.
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Affiliation(s)
- Hiromi Kimura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan.
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43
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Houtman MJC, Takanari H, Kok BGJM, van Eck M, Montagne DR, Vos MA, de Boer TP, van der Heyden MAG. Experimental Mapping of the Canine KCNJ2 and KCNJ12 Gene Structures and Functional Analysis of the Canine K(IR)2.2 ion Channel. Front Physiol 2012; 3:9. [PMID: 22363290 PMCID: PMC3277267 DOI: 10.3389/fphys.2012.00009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/12/2012] [Indexed: 12/18/2022] Open
Abstract
For many model organisms traditionally in use for cardiac electrophysiological studies, characterization of ion channel genes is lacking. We focused here on two genes encoding the inward rectifier current, KCNJ2 and KCNJ12, in the dog heart. A combination of RT-PCR, 5′-RACE, and 3′-RACE demonstrated the status of KCNJ2 as a two exon gene. The complete open reading frame (ORF) was located on the second exon. One transcription initiation site was mapped. Four differential transcription termination sites were found downstream of two consensus polyadenylation signals. The canine KCNJ12 gene was found to consist of three exons, with its ORF located on the third exon. One transcription initiation and one termination site were found. No alternative splicing was observed in right ventricle or brain cortex. The gene structure of canine KCNJ2 and KCNJ12 was conserved amongst other vertebrates, while current GenBank gene annotation was determined as incomplete. In silico translation of KCN12 revealed a non-conserved glycine rich stretch located near the carboxy-terminus of the KIR2.2 protein. However, no differences were observed when comparing dog with human KIR2.2 protein upon ectopic expression in COS-7 or HEK293 cells with respect to subcellular localization or electrophysiological properties.
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Affiliation(s)
- Marien J C Houtman
- Division Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands
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44
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Shimizu W, Horie M. Phenotypic Manifestations of Mutations in Genes Encoding Subunits of Cardiac Potassium Channels. Circ Res 2011; 109:97-109. [DOI: 10.1161/circresaha.110.224600] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Since 1995, when a potassium channel gene,
hERG
(human ether-à-go-go-related gene), now referred to as
KCNH2
, encoding the rapid component of cardiac delayed rectifier potassium channels was identified as being responsible for type 2 congenital long-QT syndrome, a number of potassium channel genes have been shown to cause different types of inherited cardiac arrhythmia syndromes. These include congenital long-QT syndrome, short-QT syndrome, Brugada syndrome, early repolarization syndrome, and familial atrial fibrillation. Genotype-phenotype correlations have been investigated in some inherited arrhythmia syndromes, and as a result, gene-specific risk stratification and gene-specific therapy and management have become available, particularly for patients with congenital long-QT syndrome. In this review article, the molecular structure and function of potassium channels, the clinical phenotype due to potassium channel gene mutations, including genotype-phenotype correlations, and the diverse mechanisms underlying the potassium channel gene–related diseases will be discussed.
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Affiliation(s)
- Wataru Shimizu
- From the Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center (W.S.), Suita, Japan, and the Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science (M.H.), Otsu, Japan
| | - Minoru Horie
- From the Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center (W.S.), Suita, Japan, and the Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science (M.H.), Otsu, Japan
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45
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Doi T, Makiyama T, Morimoto T, Haruna Y, Tsuji K, Ohno S, Akao M, Takahashi Y, Kimura T, Horie M. A Novel
KCNJ2
Nonsense Mutation, S369X, Impedes Trafficking and Causes a Limited Form of Andersen-Tawil Syndrome. ACTA ACUST UNITED AC 2011; 4:253-60. [DOI: 10.1161/circgenetics.110.958157] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Background—
Mutations in
KCNJ2
, a gene encoding the inward rectifier K
+
channel Kir2.1, are associated with Andersen-Tawil syndrome (ATS), which is characterized by (1) ventricular tachyarrhythmias associated with QT (QU)-interval prolongation, (2) periodic paralysis, and (3) dysmorphic features.
Methods and Results—
We identified a novel
KCNJ2
mutation, S369X, in a 13-year-old boy with prominent QU-interval prolongation and mild periodic paralysis. The mutation results in the truncation at the middle of the cytoplasmic C-terminal domain that eliminates the endoplasmic reticulum (ER)-to-Golgi export signal. Current recordings from Chinese hamster ovary cells transfected with
KCNJ2
-S369X exhibited significantly smaller K
+
currents compared with
KCNJ2
wild type (WT) (1 μg each) (−84±14 versus −542±46 picoamperes per picofarad [pA/pF]; −140 mV;
P
<0.0001). Coexpression of the WT and S369X subunits did not show a dominant-negative suppression effect but yielded larger currents than those of WT+S369X (−724±98 pA/pF>−[84+542] pA/pF; 1 μg each; −140 mV). Confocal microscopy analysis showed that the fluorescent protein-tagged S369X subunits were predominantly retained in the ER when expressed alone; however, the expression of S369X subunits to the plasma membrane was partially restored when coexpressed with WT. Fluorescence resonance energy transfer analysis demonstrated direct protein-protein interactions between WT and S369X subunits in the intracellular compartment.
Conclusions—
The S369X mutation causes a loss of the ER export motif. However, the trafficking deficiency can be partially rescued by directly assembling with the WT protein, resulting in a limited restoration of plasma membrane localization and channel function. This alleviation may explain why our patient presented with a relatively mild ATS phenotype.
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Affiliation(s)
- Takahiro Doi
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Takeru Makiyama
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Takeshi Morimoto
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Yoshisumi Haruna
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Keiko Tsuji
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Seiko Ohno
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Masaharu Akao
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Yoshiaki Takahashi
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Takeshi Kimura
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
| | - Minoru Horie
- From the Department of Cardiovascular Medicine (T.D., T. Makiyama, Y.H., K.T., S.O., T.K.) and Center for Medical Education (T. Morimoto), Kyoto University, Graduate School of Medicine, Kyoto, Japan; Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan (M.A.); Takahashi Clinic for Pediatric Cardiology, Otsu, Japan (Y.T.); and Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan (M.H.)
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46
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Sumitomo N. Are there juvenile and adult types in patients with catecholaminergic polymorphic ventricular tachycardia? Heart Rhythm 2011; 8:872-3. [PMID: 21338709 DOI: 10.1016/j.hrthm.2011.02.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Indexed: 11/17/2022]
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47
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Barajas-Martinez H, Hu D, Ontiveros G, Caceres G, Desai M, Burashnikov E, Scaglione J, Antzelevitch C. Biophysical and molecular characterization of a novel de novo KCNJ2 mutation associated with Andersen-Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia mimicry. CIRCULATION. CARDIOVASCULAR GENETICS 2011; 4:51-7. [PMID: 21148745 PMCID: PMC3041844 DOI: 10.1161/circgenetics.110.957696] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1 (IK1 or IKir2.1), have been identified in Andersen-Tawil syndrome. Andersen-Tawil syndrome is a multisystem inherited disease exhibiting periodic paralysis, cardiac arrhythmias, and dysmorphic features at times mimicking catecholaminergic polymorphic ventricular tachycardia. METHODS AND RESULTS Our proband displayed dysmorphic features including micrognathia, clinodactyly, and syndactyly and exhibited multiform extrasystoles and bidirectional ventricular tachycardia both at rest and during exercise testing. The patient's symptoms continued after administration of nadolol but subsided after treatment with flecainide. Molecular genetic screening revealed a novel heterozygous mutation (c.779G>C/p.R260P) in KCNJ2. Whole-cell patch-clamp studies conducted in TSA201 cells transfected with wild-type human KCNJ2 cDNA (WT-KCNJ2) yielded robust IKir2.1 but no measurable current in cells expressing the R260P mutant. Coexpression of WT and R260P-KCNJ2 (heterozygous expression) yielded a markedly reduced inward IKir2.1 compared with WT alone (-36.5±9.8 pA/pF versus -143.5±11.4 pA/pF, n=8 for both, P<0.001, respectively, at -90 mV), indicating a strong dominant negative effect of the mutant. The outward component of IKir2.1 measured at -50 mV was also markedly reduced with the heterozygous expression versus WT (0.52±5.5 pA/pF versus 23.4±6.7 pA/pF, n=8 for both, P<0.001, respectively). Immunocytochemical analysis indicates that impaired trafficking of R260P-KCNJ2 channels. CONCLUSIONS We report a novel de novo KCNJ2 mutation associated with classic phenotypic features of Andersen-Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia mimicry. The R260P mutation produces a strong dominant negative effect leading to marked suppression of IK1 secondary to a trafficking defect.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution/genetics
- Andersen Syndrome/complications
- Andersen Syndrome/diagnostic imaging
- Andersen Syndrome/genetics
- Andersen Syndrome/physiopathology
- Arrhythmias, Cardiac/complications
- Arrhythmias, Cardiac/diagnostic imaging
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/physiopathology
- Base Sequence
- Biophysical Phenomena
- Cell Line
- Child
- DNA Mutational Analysis
- Female
- Flecainide/therapeutic use
- Genes, Dominant
- Genetic Predisposition to Disease
- Humans
- Immunohistochemistry
- Male
- Molecular Sequence Data
- Mutation/genetics
- Pedigree
- Potassium Channels, Inwardly Rectifying/chemistry
- Potassium Channels, Inwardly Rectifying/genetics
- Tachycardia, Ventricular/complications
- Tachycardia, Ventricular/drug therapy
- Tachycardia, Ventricular/genetics
- Tachycardia, Ventricular/physiopathology
- Ultrasonography
- Polymorphic Catecholaminergic Ventricular Tachycardia
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Affiliation(s)
| | - Dan Hu
- Masonic Medical Research Laboratory, Utica, New York, USA
| | - Gustavo Ontiveros
- Masonic Medical Research Laboratory, Utica, New York, USA
- Fundacion para la Prevencion de la Muerte Subita-FEPREMUS and Centro de Estudios Geneticos, Buenos Aires; Argentina
| | | | - Mayurika Desai
- Masonic Medical Research Laboratory, Utica, New York, USA
| | | | - Jorge Scaglione
- Fundacion para la Prevencion de la Muerte Subita-FEPREMUS and Centro de Estudios Geneticos, Buenos Aires; Argentina
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48
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de Boer TP, Houtman MJC, Compier M, van der Heyden MAG. The mammalian K(IR)2.x inward rectifier ion channel family: expression pattern and pathophysiology. Acta Physiol (Oxf) 2010; 199:243-56. [PMID: 20331539 DOI: 10.1111/j.1748-1716.2010.02108.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Inward rectifier currents based on K(IR)2.x subunits are regarded as essential components for establishing a stable and negative resting membrane potential in many excitable cell types. Pharmacological inhibition, null mutation in mice and dominant positive and negative mutations in patients reveal some of the important functions of these channels in their native tissues. Here we review the complex mammalian expression pattern of K(IR)2.x subunits and relate these to the outcomes of functional inhibition of the resultant channels. Correlations between expression and function in muscle and bone tissue are observed, while we recognize a discrepancy between neuronal expression and function.
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Affiliation(s)
- T P de Boer
- Department of Medical Physiology, UMCU, Utrecht, the Netherlands
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