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Meyer KM, Malhotra N, Kwak JS, El Refaey M. Relevance of KCNJ5 in Pathologies of Heart Disease. Int J Mol Sci 2023; 24:10849. [PMID: 37446026 PMCID: PMC10341679 DOI: 10.3390/ijms241310849] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Abnormalities in G-protein-gated inwardly rectifying potassium (GIRK) channels have been implicated in diseased states of the cardiovascular system; however, the role of GIRK4 (Kir3.4) in cardiac physiology and pathophysiology has yet to be completely understood. Within the heart, the KACh channel, consisting of two GIRK1 and two GIRK4 subunits, plays a major role in modulating the parasympathetic nervous system's influence on cardiac physiology. Being that GIRK4 is necessary for the functional KACh channel, KCNJ5, which encodes GIRK4, it presents as a therapeutic target for cardiovascular pathology. Human variants in KCNJ5 have been identified in familial hyperaldosteronism type III, long QT syndrome, atrial fibrillation, and sinus node dysfunction. Here, we explore the relevance of KCNJ5 in each of these diseases. Further, we address the limitations and complexities of discerning the role of KCNJ5 in cardiovascular pathophysiology, as identical human variants of KCNJ5 have been identified in several diseases with overlapping pathophysiology.
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Affiliation(s)
- Karisa M. Meyer
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Nipun Malhotra
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jung seo Kwak
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Mona El Refaey
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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2
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Precision medicine for long QT syndrome: patient-specific iPSCs take the lead. Expert Rev Mol Med 2023; 25:e5. [PMID: 36597672 DOI: 10.1017/erm.2022.43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Long QT syndrome (LQTS) is a detrimental arrhythmia syndrome mainly caused by dysregulated expression or aberrant function of ion channels. The major clinical symptoms of ventricular arrhythmia, palpitations and syncope vary among LQTS subtypes. Susceptibility to malignant arrhythmia is a result of delayed repolarisation of the cardiomyocyte action potential (AP). There are 17 distinct subtypes of LQTS linked to 15 autosomal dominant genes with monogenic mutations. However, due to the presence of modifier genes, the identical mutation may result in completely different clinical manifestations in different carriers. In this review, we describe the roles of various ion channels in orchestrating APs and discuss molecular aetiologies of various types of LQTS. We highlight the usage of patient-specific induced pluripotent stem cell (iPSC) models in characterising fundamental mechanisms associated with LQTS. To mitigate the outcomes of LQTS, treatment strategies are initially focused on small molecules targeting ion channel activities. Next-generation treatments will reap the benefits from development of LQTS patient-specific iPSC platform, which is bolstered by the state-of-the-art technologies including whole-genome sequencing, CRISPR genome editing and machine learning. Deep phenotyping and high-throughput drug testing using LQTS patient-specific cardiomyocytes herald the upcoming precision medicine in LQTS.
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Souza DS, Chignalia AZ, Carvalho-de-Souza JL. Modulation of cardiac voltage-activated K + currents by glypican 1 heparan sulfate proteoglycan. Life Sci 2022; 308:120916. [PMID: 36049528 PMCID: PMC11105158 DOI: 10.1016/j.lfs.2022.120916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/20/2022]
Abstract
BACKGROUND Glypican 1 (Gpc1) is a heparan sulfate proteoglycan attached to the cell membrane via a glycosylphosphatidylinositol anchor, where it holds glycosaminoglycans nearby. We have recently shown that Gpc1 knockout (Gpc1-/-) mice feature decreased systemic blood pressure. To date, none has been reported regarding the role of Gpc1 on the electrical properties of the heart and specifically, in regard to a functional interaction between Gpc1 and voltage-gated K+ channels. METHODS We used echocardiography and in vivo (electrocardiographic recordings) and in vitro (patch clamping) electrophysiology to study mechanical and electric properties of mice hearts. We used RT-PCR to probe K+ channels' gene transcription in heart tissue. RESULTS Gpc1-/- hearts featured increased cardiac stroke volume and preserved ejection fraction. Gpc1-/- electrocardiograms showed longer QT intervals, abnormalities in the ST segment, and delayed T waves, corroborated by longer action potentials in isolated ventricular cardiomyocytes. In voltage-clamp, these cells showed decreased Ito and IK voltage-activated K+ current densities. Moreover, IK showed activation at less negative voltages, but a higher level of inactivation at a given membrane potential. Kcnh2 and Kcnq1 voltage-gated K+ channels subunits' transcripts were remarkably more abundant in heart tissues from Gpc1-/- mice, suggesting that Gpc1 may interfere in the steps between transcription and translation in these cases. CONCLUSION Our data reveals an unprecedented connection between Gpc1 and voltage-gated K+ channels expressed in the heart and this knowledge contributes to the understanding of the role of this HSPG in cardiac function which may play a role in the development of cardiovascular disease.
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Affiliation(s)
- Diego Santos Souza
- Department of Anesthesiology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Andreia Zago Chignalia
- Department of Anesthesiology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA; Department of Physiology, College of Medicine University of Arizona, Tucson, AZ 85724, USA; Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85724, USA
| | - Joao Luis Carvalho-de-Souza
- Department of Anesthesiology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA; Department of Physiology, College of Medicine University of Arizona, Tucson, AZ 85724, USA; Department of Ophthalmology and Visual Sciences, College of Medicine, University of Arizona, Tucson, AZ 85724, USA; BIO5 Institute, University of Arizona, Tucson, AZ 85724, USA.
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Young LJ, Antwi-Boasiako S, Ferrall J, Wold LE, Mohler PJ, El Refaey M. Genetic and non-genetic risk factors associated with atrial fibrillation. Life Sci 2022; 299:120529. [PMID: 35385795 PMCID: PMC9058231 DOI: 10.1016/j.lfs.2022.120529] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 12/15/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmic disorder and its prevalence in the United States is projected to increase to more than twelve million cases in 2030. AF increases the risk of other forms of cardiovascular disease, including stroke. As the incidence of atrial fibrillation increases dramatically with age, it is paramount to elucidate risk factors underlying AF pathogenesis. Here, we review tissue and cellular pathways underlying AF, as well as critical components that impact AF susceptibility including genetic and environmental risk factors. Finally, we provide the latest information on potential links between SARS-CoV-2 and human AF. Improved understanding of mechanistic pathways holds promise in preventative care and early diagnostics, and also introduces novel targeted forms of therapy that might attenuate AF progression and maintenance.
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Affiliation(s)
- Lindsay J Young
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Steve Antwi-Boasiako
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Joel Ferrall
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Loren E Wold
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; College of Nursing, The Ohio State University, Columbus, OH, USA
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH, USA
| | - Mona El Refaey
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH, USA.
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5
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Wang M, Tu X. The Genetics and Epigenetics of Ventricular Arrhythmias in Patients Without Structural Heart Disease. Front Cardiovasc Med 2022; 9:891399. [PMID: 35783865 PMCID: PMC9240357 DOI: 10.3389/fcvm.2022.891399] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/25/2022] [Indexed: 12/19/2022] Open
Abstract
Ventricular arrhythmia without structural heart disease is an arrhythmic disorder that occurs in structurally normal heart and no transient or reversible arrhythmia factors, such as electrolyte disorders and myocardial ischemia. Ventricular arrhythmias without structural heart disease can be induced by multiple factors, including genetics and environment, which involve different genetic and epigenetic regulation. Familial genetic analysis reveals that cardiac ion-channel disorder and dysfunctional calcium handling are two major causes of this type of heart disease. Genome-wide association studies have identified some genetic susceptibility loci associated with ventricular tachycardia and ventricular fibrillation, yet relatively few loci associated with no structural heart disease. The effects of epigenetics on the ventricular arrhythmias susceptibility genes, involving non-coding RNAs, DNA methylation and other regulatory mechanisms, are gradually being revealed. This article aims to review the knowledge of ventricular arrhythmia without structural heart disease in genetics, and summarizes the current state of epigenetic regulation.
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Anderson A, Vo BN, de Velasco EMF, Hopkins CR, Weaver CD, Wickman K. Characterization of VU0468554, a New Selective Inhibitor of Cardiac G Protein-Gated Inwardly Rectifying K + Channels. Mol Pharmacol 2021; 100:540-547. [PMID: 34503975 DOI: 10.1124/molpharm.121.000311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/01/2021] [Indexed: 11/22/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are critical mediators of excitability in the heart and brain. Enhanced GIRK-channel activity has been implicated in the pathogenesis of supraventricular arrhythmias, including atrial fibrillation. The lack of selective pharmacological tools has impeded efforts to investigate the therapeutic potential of cardiac GIRK-channel interventions in arrhythmias. Here, we characterize a recently identified GIRK-channel inhibitor, VU0468554. Using whole-cell electrophysiological approaches and primary cultures of sinoatrial nodal cells and hippocampal neurons, we show that VU0468554 more effectively inhibits the cardiac GIRK channel than the neuronal GIRK channel. Concentration-response experiments suggest that VU0468554 inhibits Gβγ-activated GIRK channels in noncompetitive and potentially uncompetitive fashion. In contrast, VU0468554 competitively inhibits GIRK-channel activation by ML297, a GIRK-channel activator containing the same chemical scaffold as VU0468554. In the isolated heart model, VU0468554 partially reversed carbachol-induced bradycardia in hearts from wild-type mice but not Girk4-/- mice. Collectively, these data suggest that VU0468554 represents a promising new pharmacological tool for targeting cardiac GIRK channels with therapeutic implications for relevant cardiac arrhythmias. SIGNIFICANCE STATEMENT: Although cardiac GIRK-channel inhibition shows promise for the treatment of supraventricular arrhythmias, the absence of subtype-selective channel inhibitors has hindered exploration into this therapeutic strategy. This study utilizes whole-cell patch-clamp electrophysiology to characterize the new GIRK-channel inhibitor VU0468554 in human embryonic kidney 293T cells and primary cultures. We report that VU0468554 exhibits a favorable pharmacodynamic profile for cardiac over neuronal GIRK channels and partially reverses GIRK-mediated bradycardia in the isolated mouse heart model.
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Affiliation(s)
- Allison Anderson
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Baovi N Vo
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Ezequiel Marron Fernandez de Velasco
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Corey R Hopkins
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - C David Weaver
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Kevin Wickman
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
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Targeting of Potassium Channels in Cardiac Arrhythmias. Trends Pharmacol Sci 2021; 42:491-506. [PMID: 33858691 DOI: 10.1016/j.tips.2021.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
Cardiomyocytes are endowed with a complex repertoire of ion channels, responsible for the generation of action potentials (APs), travelling waves of electrical excitation, propagating throughout the heart and leading to cardiac contractions. Cardiac AP waveforms are shaped by a striking diversity of K+ channels. The pivotal role of K+ channels in cardiac health and disease is underscored by the dramatic impact that K+ channel dysfunction has on cardiac arrhythmias. The development of drugs targeted to specific K+ channels is expected to provide an optimized approach to antiarrhythmic therapy. Here, we review the functional roles of cardiac potassium channels under normal and diseased states. We survey current antiarrhythmic drugs (AADs) targeted to voltage-gated and Ca2+-activated K+ channels and highlight future research opportunities.
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Wallace MJ, El Refaey M, Mesirca P, Hund TJ, Mangoni ME, Mohler PJ. Genetic Complexity of Sinoatrial Node Dysfunction. Front Genet 2021; 12:654925. [PMID: 33868385 PMCID: PMC8047474 DOI: 10.3389/fgene.2021.654925] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 03/01/2021] [Indexed: 12/13/2022] Open
Abstract
The pacemaker cells of the cardiac sinoatrial node (SAN) are essential for normal cardiac automaticity. Dysfunction in cardiac pacemaking results in human sinoatrial node dysfunction (SND). SND more generally occurs in the elderly population and is associated with impaired pacemaker function causing abnormal heart rhythm. Individuals with SND have a variety of symptoms including sinus bradycardia, sinus arrest, SAN block, bradycardia/tachycardia syndrome, and syncope. Importantly, individuals with SND report chronotropic incompetence in response to stress and/or exercise. SND may be genetic or secondary to systemic or cardiovascular conditions. Current management of patients with SND is limited to the relief of arrhythmia symptoms and pacemaker implantation if indicated. Lack of effective therapeutic measures that target the underlying causes of SND renders management of these patients challenging due to its progressive nature and has highlighted a critical need to improve our understanding of its underlying mechanistic basis of SND. This review focuses on current information on the genetics underlying SND, followed by future implications of this knowledge in the management of individuals with SND.
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Affiliation(s)
- Michael J. Wallace
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Mona El Refaey
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Pietro Mesirca
- CNRS, INSERM, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France
- Laboratory of Excellence ICST, Montpellier, France
| | - Thomas J. Hund
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, United States
| | - Matteo E. Mangoni
- CNRS, INSERM, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France
- Laboratory of Excellence ICST, Montpellier, France
| | - Peter J. Mohler
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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Melgar Quicaño LA, Chipa Ccasani F. [Congenital long QT syndrome]. ARCHIVOS PERUANOS DE CARDIOLOGIA Y CIRUGIA CARDIOVASCULAR 2021; 2:49-57. [PMID: 37727265 PMCID: PMC10506569 DOI: 10.47487/apcyccv.v2i1.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 09/21/2023]
Abstract
Congenital long QT syndrome (LQTS) represents a group of heart diseases of genetic origin characterized by prolongation of the QT interval and an abnormal T wave on the electrocardiogram (ECG). They can have a dominant or recessive expression, the latter associated with sensorineural deafness. In both cases, its clinical presentation is associated with recurrent syncope and sudden death as a consequence of ventricular tachycardia, specifically Torsades de Pointes. Currently they are classified according to the specific genetic defect, being able to compromise around 16 genes and almost 2000 mutations. It should be suspected in individuals with related symptoms, electrocardiographic findings, and family history. Management is based on the reduction or elimination of symptoms, and concomitantly the prevention of sudden death (SD), in those children with congenital deafness, the management requires the application of the otolaryngologist specialist's own measures. The cardiovascular management implies the modification of lifestyles, mainly the prohibition of competitive sports, including swimming, avoiding exposure to loud sounds or triggers. The medications used include beta-blockers, and more rarely flecainide, ranozaline, and verapamil; invasive management consists of the implantation of a cardioverter defibrillator or even left sympathetic denervation, each with its own risks and benefits. In any of the cases, we must avoid the circumstances that increase the QT interval, as well as carry out the appropriate analysis of the benefits and risks of each possible invasive measure.
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Affiliation(s)
| | - Fredy Chipa Ccasani
- Instituto Nacional de Salud del Niño, San Borja. Lima, PerúInstituto Nacional de Salud del NiñoLimaPerú
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Kuß J, Stallmeyer B, Goldstein M, Rinné S, Pees C, Zumhagen S, Seebohm G, Decher N, Pott L, Kienitz MC, Schulze-Bahr E. Familial Sinus Node Disease Caused by a Gain of GIRK (G-Protein Activated Inwardly Rectifying K + Channel) Channel Function. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2020; 12:e002238. [PMID: 30645171 DOI: 10.1161/circgen.118.002238] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Inherited forms of sinus node dysfunction (SND) clinically include bradycardia, sinus arrest, and chronotropic incompetence and may serve as disease models to understand sinus node physiology and impulse generation. Recently, a gain-of-function mutation in the G-protein gene GNB2 led to enhanced activation of the GIRK (G-protein activated inwardly rectifying K+ channel). Thus, human cardiac GIRK channels are important for heart rate regulation and subsequently, genes encoding their subunits Kir3.1 and Kir3.4 ( KCNJ3 and KCNJ5) are potential candidates for inherited SND in human. METHODS We performed a combined approach of targeted sequencing of KCNJ3 and KCNJ5 in 52 patients with idiopathic SND and subsequent whole exome sequencing of additional family members in a genetically affected patient. A putative novel disease-associated gene variant was functionally analyzed by voltage-clamp experiments using various heterologous cell expression systems (Xenopus oocytes, CHO cells, and rat atrial cardiomyocytes). RESULTS In a 3-generation family with SND we identified a novel variant in KCNJ5 which leads to an amino acid substitution (p.Trp101Cys) in the first transmembrane domain of the Kir3.4 subunit of the cardiac GIRK channel. The identified variant cosegregated with the disease in the family and was absent in the Exome Variant Server and Exome Aggregation Consortium databases. Expression of mutant Kir3.4 (±native Kir3.1) in different heterologous cell expression systems resulted in increased GIRK currents ( IK,ACh) and a reduced inward rectification which was not compensated by intracellular spermidine. Moreover, in silico modeling of heterotetrameric mutant GIRK channels indicates a structurally altered binding site for spermine. CONCLUSIONS For the first time, an inherited gain-of-function mutation in the human GIRK3.4 causes familial human SND. The increased activity of GIRK channels is likely to lead to a sustained hyperpolarization of pacemaker cells and thereby reduces heart rate. Modulation of human GIRK channels may pave a way for further treatment of cardiac pacemaking.
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Affiliation(s)
- Johanna Kuß
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Matthias Goldstein
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Christiane Pees
- Department of Pediatric Cardiology, University Children's Hospital Vienna, Austria (C.P.)
| | - Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Lutz Pott
- Department of Cardiovascular Medicine, Institute of Physiology, Ruhr-University Bochum, Germany (L.P., M.-C.K.)
| | - Marie-Cécile Kienitz
- Department of Cardiovascular Medicine, Institute of Physiology, Ruhr-University Bochum, Germany (L.P., M.-C.K.)
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
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14
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Giudicessi JR, Wilde AAM, Ackerman MJ. The genetic architecture of long QT syndrome: A critical reappraisal. Trends Cardiovasc Med 2018; 28:453-464. [PMID: 29661707 DOI: 10.1016/j.tcm.2018.03.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 12/19/2022]
Abstract
Collectively, the completion of the Human Genome Project and subsequent development of high-throughput next-generation sequencing methodologies have revolutionized genomic research. However, the rapid sequencing and analysis of thousands upon thousands of human exomes and genomes has taught us that most genes, including those known to cause heritable cardiovascular disorders such as long QT syndrome, harbor an unexpected background rate of rare, and presumably innocuous, non-synonymous genetic variation. In this Review, we aim to reappraise the genetic architecture underlying both the acquired and congenital forms of long QT syndrome by examining how the clinical phenotype associated with and background genetic variation in long QT syndrome-susceptibility genes impacts the clinical validity of existing gene-disease associations and the variant classification and reporting strategies that serve as the foundation for diagnostic long QT syndrome genetic testing.
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Affiliation(s)
- John R Giudicessi
- Department of Cardiovascular Medicine (Cardiovascular Diseases Fellowship and Clinician-Investigator Training Programs), Mayo Clinic, Rochester, MN, United States
| | - Arthur A M Wilde
- Department of Medicine (Division of Cardiology), Columbia University Irving Medical Center, New York, NY, United States; Department of Clinical & Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, United States.
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Ion Channel Disorders and Sudden Cardiac Death. Int J Mol Sci 2018; 19:ijms19030692. [PMID: 29495624 PMCID: PMC5877553 DOI: 10.3390/ijms19030692] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 12/19/2022] Open
Abstract
Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias. These disorders may have low penetrance and expressivity, making clinical diagnosis often challenging. However, because sudden cardiac death might be the first presenting symptom of the disease, early diagnosis becomes essential. Genetic testing might be helpful in this regard, providing a definite diagnosis in some patients. Yet important limitations still exist, with a significant proportion of patients remaining with no causative mutation identifiable after genetic testing. This review aims to provide the latest knowledge on the genetic basis of cardiac channelopathies and discuss the role of the affected proteins in the pathophysiology of each one of these diseases.
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Expression and relevance of the G protein-gated K + channel in the mouse ventricle. Sci Rep 2018; 8:1192. [PMID: 29352184 PMCID: PMC5775354 DOI: 10.1038/s41598-018-19719-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022] Open
Abstract
The atrial G protein-gated inwardly rectifying K+ (GIRK) channel is a critical mediator of parasympathetic influence on cardiac physiology. Here, we probed the details and relevance of the GIRK channel in mouse ventricle. mRNAs for the atrial GIRK channel subunits (GIRK1, GIRK4), M2 muscarinic receptor (M2R), and RGS6, a negative regulator of atrial GIRK-dependent signaling, were detected in mouse ventricle at relatively low levels. The cholinergic agonist carbachol (CCh) activated small GIRK currents in adult wild-type ventricular myocytes that exhibited relatively slow kinetics and low CCh sensitivity; these currents were absent in ventricular myocytes from Girk1-/- or Girk4-/- mice. While loss of GIRK channels attenuated the CCh-induced shortening of action potential duration and suppression of ventricular myocyte excitability, selective ablation of GIRK channels in ventricle had no effect on heart rate, heart rate variability, or electrocardiogram parameters at baseline or after CCh injection. Additionally, loss of ventricular GIRK channels did not impact susceptibility to ventricular arrhythmias. These data suggest that the mouse ventricular GIRK channel is a GIRK1/GIRK4 heteromer, and show that while it contributes to the cholinergic suppression of ventricular myocyte excitability, this influence does not substantially impact cardiac physiology or ventricular arrhythmogenesis in the mouse.
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Magi S, Lariccia V, Maiolino M, Amoroso S, Gratteri S. Sudden cardiac death: focus on the genetics of channelopathies and cardiomyopathies. J Biomed Sci 2017; 24:56. [PMID: 28810874 PMCID: PMC5556354 DOI: 10.1186/s12929-017-0364-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 08/09/2017] [Indexed: 01/22/2023] Open
Abstract
Sudden cardiac death (SCD) describes a natural and unexpected death from cardiac causes occurring within a short period of time (generally within 1 h of symptom onset) in the absence of any other potentially lethal condition. Most SCD-related diseases have a genetic basis; in particular congenital cardiac channelopathies and cardiomyopathies have been described as leading causes of SCD. Congenital cardiac channelopathies are primary electric disorders caused by mutations affecting genes encoding cardiac ion channels or associated proteins, whereas cardiomyopathies are related to mutations in genes encoding several categories of proteins, including those of sarcomeres, desmosomes, the cytoskeleton, and the nuclear envelope. The purpose of this review is to provide a general overview of the main genetic variants that have been linked to the major congenital cardiac channelopathies and cardiomyopathies. Functional alterations of the related proteins are also described.
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Affiliation(s)
- Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy.
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
| | - Marta Maiolino
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
| | - Santo Gratteri
- Department of Health Sciences, University "Magna Graecia", 88100, Catanzaro, Italy
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18
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Harmer SC, Tinker A. The impact of recent advances in genetics in understanding disease mechanisms underlying the long QT syndromes. Biol Chem 2017; 397:679-93. [PMID: 26910742 DOI: 10.1515/hsz-2015-0306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/18/2016] [Indexed: 11/15/2022]
Abstract
Long QT syndrome refers to a characteristic abnormality of the electrocardiogram and it is associated with a form of ventricular tachycardia known as torsade-de-pointes and sudden arrhythmic death. It can occur as part of a hereditary syndrome or can be acquired usually because of drug administration. Here we review recent genetic, molecular and cellular discoveries and outline how they have furthered our understanding of this disease. Specifically we focus on compound mutations, genome wide association studies of QT interval, modifier genes and the therapeutic implications of this recent work.
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Tauber P, Penton D, Stindl J, Humberg E, Tegtmeier I, Sterner C, Beuschlein F, Reincke M, Barhanin J, Bandulik S, Warth R. Pharmacology and pathophysiology of mutated KCNJ5 found in adrenal aldosterone-producing adenomas. Endocrinology 2014; 155:1353-62. [PMID: 24506072 DOI: 10.1210/en.2013-1944] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Somatic mutations of the potassium channel KCNJ5 are found in 40% of aldosterone producing adenomas (APAs). APA-related mutations of KCNJ5 lead to a pathological Na(+) permeability and a rise in cytosolic Ca(2+), the latter presumably by depolarizing the membrane and activating voltage-gated Ca(2+) channels. The aim of this study was to further investigate the effects of mutated KCNJ5 channels on intracellular Na(+) and Ca(2+) homeostasis in human adrenocortical NCI-H295R cells. Expression of mutant KCNJ5 led to a 2-fold increase in intracellular Na(+) and, in parallel, to a substantial rise in intracellular Ca(2+). The increase in Ca(2+) appeared to be caused by activation of voltage-gated Ca(2+) channels and by an impairment of Ca(2+) extrusion by Na(+)/Ca(2+) exchangers. The mutated KCNJ5 exhibited a pharmacological profile that differed from the one of wild-type channels. Mutated KCNJ5 was less Ba(2+) and tertiapin-Q sensitive but was inhibited by blockers of Na(+) and Ca(2+)-transporting proteins, such as verapamil and amiloride. The clinical use of these drugs might influence aldosterone levels in APA patients with KCNJ5 mutations. This might implicate diagnostic testing of APAs and could offer new therapeutic strategies.
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Affiliation(s)
- P Tauber
- Medical Cell Biology (P.T., J.S., E.H., I.T., C.S., S.B., R.W.), University of Regensburg, 93053 Regensburg, Germany; Laboratoire de PhysioMédecine Moléculaire (D.P., J.B.), Centre National de la Recherche Scientifique, and Université de Nice Sophia Antipolis, FRE3472-Laboratoire de PhysioMédecine Moléculaire, 06108 Nice Cedex, France; Laboratories of Excellence, Ion Channel Science and Therapeutics (D.P., J.B.), France; and Medizinische Klinik und Poliklinik IV (F.B., M.R.), Ludwig-Maximilians-Universität, 80336 Munich, Germany
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Wydeven N, Posokhova E, Xia Z, Martemyanov KA, Wickman K. RGS6, but not RGS4, is the dominant regulator of G protein signaling (RGS) modulator of the parasympathetic regulation of mouse heart rate. J Biol Chem 2013; 289:2440-9. [PMID: 24318880 DOI: 10.1074/jbc.m113.520742] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parasympathetic activity decreases heart rate (HR) by inhibiting pacemaker cells in the sinoatrial node (SAN). Dysregulation of parasympathetic influence has been linked to sinus node dysfunction and arrhythmia. RGS (regulator of G protein signaling) proteins are negative modulators of the parasympathetic regulation of HR and the prototypical M2 muscarinic receptor (M2R)-dependent signaling pathway in the SAN that involves the muscarinic-gated atrial K(+) channel IKACh. Both RGS4 and RGS6-Gβ5 have been implicated in these processes. Here, we used Rgs4(-/-), Rgs6(-/-), and Rgs4(-/-):Rgs6(-/-) mice to compare the relative influence of RGS4 and RGS6 on parasympathetic regulation of HR and M2R-IKACh-dependent signaling in the SAN. In retrogradely perfused hearts, ablation of RGS6, but not RGS4, correlated with decreased resting HR, increased heart rate variability, and enhanced sensitivity to the negative chronotropic effects of the muscarinic agonist carbachol. Similarly, loss of RGS6, but not RGS4, correlated with enhanced sensitivity of the M2R-IKACh signaling pathway in SAN cells to carbachol and a significant slowing of M2R-IKACh deactivation rate. Surprisingly, concurrent genetic ablation of RGS4 partially rescued some deficits observed in Rgs6(-/-) mice. These findings, together with those from an acute pharmacologic approach in SAN cells from Rgs6(-/-) and Gβ5(-/-) mice, suggest that the partial rescue of phenotypes in Rgs4(-/-):Rgs6(-/-) mice is attributable to another R7 RGS protein whose influence on M2R-IKACh signaling is masked by RGS4. Thus, RGS6-Gβ5, but not RGS4, is the primary RGS modulator of parasympathetic HR regulation and SAN M2R-IKACh signaling in mice.
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Affiliation(s)
- Nicole Wydeven
- From the Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455 and
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Luján R, Marron Fernandez de Velasco E, Aguado C, Wickman K. New insights into the therapeutic potential of Girk channels. Trends Neurosci 2013; 37:20-9. [PMID: 24268819 DOI: 10.1016/j.tins.2013.10.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/01/2023]
Abstract
G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.
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Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | | | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, 321 Church Street South East, Minneapolis, MN 55455, USA.
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Phenotypic characterization of a family with long QT syndrome 13: A different type of variable penetrance. Heart Rhythm 2013; 10:1507-8. [DOI: 10.1016/j.hrthm.2013.07.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Indexed: 11/18/2022]
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