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Butler AS, Ascione R, Marrion NV, Harmer SC, Hancox JC. In situ monolayer patch clamp of acutely stimulated human iPSC-derived cardiomyocytes promotes consistent electrophysiological responses to SK channel inhibition. Sci Rep 2024; 14:3185. [PMID: 38326449 PMCID: PMC10850090 DOI: 10.1038/s41598-024-53571-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 02/02/2024] [Indexed: 02/09/2024] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) represent an in vitro model of cardiac function. Isolated iPSC-CMs, however, exhibit electrophysiological heterogeneity which hinders their utility in the study of certain cardiac currents. In the healthy adult heart, the current mediated by small conductance, calcium-activated potassium (SK) channels (ISK) is atrial-selective. Functional expression of ISK within atrial-like iPSC-CMs has not been explored thoroughly. The present study therefore aimed to investigate atrial-like iPSC-CMs as a model system for the study of ISK. iPSCs were differentiated using retinoic acid (RA) to produce iPSC-CMs which exhibited an atrial-like phenotype (RA-iPSC-CMs). Only 18% of isolated RA-iPSC-CMs responded to SK channel inhibition by UCL1684 and isolated iPSC-CMs exhibited substantial cell-to-cell electrophysiological heterogeneity. This variability was significantly reduced by patch clamp of RA-iPSC-CMs in situ as a monolayer (iPSC-ML). A novel method of electrical stimulation was developed to facilitate recording from iPSC-MLs via In situ Monolayer Patch clamp of Acutely Stimulated iPSC-CMs (IMPASC). Using IMPASC, > 95% of iPSC-MLs could be paced at a 1 Hz. In contrast to isolated RA-iPSC-CMs, 100% of RA-iPSC-MLs responded to UCL1684, with APD50 being prolonged by 16.0 ± 2.0 ms (p < 0.0001; n = 12). These data demonstrate that in conjunction with IMPASC, RA-iPSC-MLs represent an improved model for the study of ISK. IMPASC may be of wider value in the study of other ion channels that are inconsistently expressed in isolated iPSC-CMs and in pharmacological studies.
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Affiliation(s)
- Andrew S Butler
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Raimondo Ascione
- Bristol Heart Institute and Translational Biomedical Research Centre, Faculty of Health Science, University of Bristol, Bristol, BS2 8HW, UK
| | - Neil V Marrion
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Stephen C Harmer
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK.
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK.
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2
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Hu W, Zhang W, Zhang K, Al-Moubarak E, Zhang Y, Harmer SC, Hancox JC, Zhang H. Evaluating pro-arrhythmogenic effects of the T634S-hERG mutation: insights from a simulation study. Interface Focus 2023; 13:20230035. [PMID: 38106919 PMCID: PMC10722218 DOI: 10.1098/rsfs.2023.0035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/06/2023] [Indexed: 12/19/2023] Open
Abstract
A mutation to serine of a conserved threonine (T634S) in the hERG K+ channel S6 pore region has been identified as a variant of uncertain significance, showing a loss-of-function effect. However, its potential consequences for ventricular excitation and arrhythmogenesis have not been reported. This study evaluated possible functional effects of the T634S-hERG mutation on ventricular excitation and arrhythmogenesis by using multi-scale computer models of the human ventricle. A Markov chain model of the rapid delayed rectifier potassium current (IKr) was reconstructed for wild-type and T634S-hERG mutant conditions and incorporated into the ten Tusscher et al. models of human ventricles at cell and tissue (1D, 2D and 3D) levels. Possible functional impacts of the T634S-hERG mutation were evaluated by its effects on action potential durations (APDs) and their rate-dependence (APDr) at the cell level; and on the QT interval of pseudo-ECGs, tissue vulnerability to unidirectional conduction block (VW), spiral wave dynamics and repolarization dispersion at the tissue level. It was found that the T634S-hERG mutation prolonged cellular APDs, steepened APDr, prolonged the QT interval, increased VW, destablized re-entry and augmented repolarization dispersion across the ventricle. Collectively, these results imply potential pro-arrhythmic effects of the T634S-hERG mutation, consistent with LQT2.
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Affiliation(s)
- Wei Hu
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Wenfeng Zhang
- College of Computer and Information Science, Chongqing Normal University, Chongqing, People's Republic of China
| | - Kevin Zhang
- Southmead Hospital, North Bristol Trust, Bristol, UK
| | - Ehab Al-Moubarak
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Yihong Zhang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Stephen C. Harmer
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Jules C. Hancox
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Henggui Zhang
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, People's Republic of China
- Beijing Academy of Artificial Intelligence, Beijing 100084, People's Republic of China
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3
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Hancox JC, Copeland CS, Harmer SC, Henderson G. New synthetic cannabinoids and the potential for cardiac arrhythmia risk. J Mol Cell Cardiol Plus 2023; 6:100049. [PMID: 38143960 PMCID: PMC10739592 DOI: 10.1016/j.jmccpl.2023.100049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/14/2023] [Accepted: 09/14/2023] [Indexed: 12/26/2023]
Abstract
Synthetic cannabinoid receptor agonists (SCRAs) have been associated with QT interval prolongation. Limited preclinical information on SCRA effects on cardiac electrogenesis results from the rapid emergence of new compounds and restricted research availability. We used two machine-learning-based tools to evaluate seven novel SCRAs' interaction potential with the hERG potassium channel, an important drug antitarget. Five SCRAs were predicted to have the ability to block the hERG channel by both prediction tools; ADB-FUBIATA was predicted to be a strong hERG blocker. ADB-5Br-INACA and ADB-4en-PINACA showed varied predictions. These findings highlight potentially proarrhythmic hERG block by novel SCRAs, necessitating detailed safety evaluations.
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Affiliation(s)
- Jules C. Hancox
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Caroline S. Copeland
- Institute of Pharmaceutical Science, King's College London, UK
- Centre for Pharmaceutical Medicine Research, King's College London, UK
| | - Stephen C. Harmer
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Graeme Henderson
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
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Hancox JC, Du CY, Butler A, Zhang Y, Dempsey CE, Harmer SC, Zhang H. Pro-arrhythmic effects of gain-of-function potassium channel mutations in the short QT syndrome. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220165. [PMID: 37122211 PMCID: PMC10150212 DOI: 10.1098/rstb.2022.0165] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
The congenital short QT syndrome (SQTS) is a rare condition characterized by abbreviated rate-corrected QT (QTc) intervals on the electrocardiogram and by increased susceptibility to both atrial and ventricular arrhythmias and sudden death. Although mutations to multiple genes have been implicated in the SQTS, evidence of causality is particularly strong for the first three (SQT1-3) variants: these result from gain-of-function mutations in genes that encode K+ channel subunits responsible, respectively, for the IKr, IKs and IK1 cardiac potassium currents. This article reviews evidence for the impact of SQT1-3 missense potassium channel gene mutations on the electrophysiological properties of IKr, IKs and IK1 and of the links between these changes and arrhythmia susceptibility. Data from experimental and simulation studies and future directions for research in this field are considered. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- J C Hancox
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - C Y Du
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - A Butler
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Y Zhang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - C E Dempsey
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - S C Harmer
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - H Zhang
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
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Zawada D, Kornherr J, Meier AB, Santamaria G, Dorn T, Nowak-Imialek M, Ortmann D, Zhang F, Lachmann M, Dreßen M, Ortiz M, Mascetti VL, Harmer SC, Nobles M, Tinker A, De Angelis MT, Pedersen RA, Grote P, Laugwitz KL, Moretti A, Goedel A. Retinoic acid signaling modulation guides in vitro specification of human heart field-specific progenitor pools. Nat Commun 2023; 14:1722. [PMID: 37012244 PMCID: PMC10070453 DOI: 10.1038/s41467-023-36764-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 02/15/2023] [Indexed: 04/05/2023] Open
Abstract
Cardiogenesis relies on the precise spatiotemporal coordination of multiple progenitor populations. Understanding the specification and differentiation of these distinct progenitor pools during human embryonic development is crucial for advancing our knowledge of congenital cardiac malformations and designing new regenerative therapies. By combining genetic labelling, single-cell transcriptomics, and ex vivo human-mouse embryonic chimeras we uncovered that modulation of retinoic acid signaling instructs human pluripotent stem cells to form heart field-specific progenitors with distinct fate potentials. In addition to the classical first and second heart fields, we observed the appearance of juxta-cardiac field progenitors giving rise to both myocardial and epicardial cells. Applying these findings to stem-cell based disease modelling we identified specific transcriptional dysregulation in first and second heart field progenitors derived from stem cells of patients with hypoplastic left heart syndrome. This highlights the suitability of our in vitro differentiation platform for studying human cardiac development and disease.
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Affiliation(s)
- Dorota Zawada
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Jessica Kornherr
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Anna B Meier
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Gianluca Santamaria
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- Department of Experimental and Clinical Medicine, University "Magna Graecia", Catanzaro, Italy
| | - Tatjana Dorn
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Monika Nowak-Imialek
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Daniel Ortmann
- Department of Surgery, University of Cambridge, Cambridge, UK
- Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | - Fangfang Zhang
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Mark Lachmann
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
| | - Martina Dreßen
- German Heart Center Munich, Department of Cardiovascular Surgery, Institute Insure - Technical University of Munich, School of Medicine and Health, Munich, Germany
| | | | - Victoria L Mascetti
- Bristol Heart Institute, Bristol Medical School, Translational Health Sciences, Bristol, UK
| | - Stephen C Harmer
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Muriel Nobles
- Clinical Pharmacology & Precision Medicine, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Andrew Tinker
- Clinical Pharmacology & Precision Medicine, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Maria Teresa De Angelis
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany
- Department of Experimental and Clinical Medicine, University "Magna Graecia", Catanzaro, Italy
| | - Roger A Pedersen
- Department of Obstetrics and Gynecology, Stanford School of Medicine, Stanford University, Stanford, USA
| | - Phillip Grote
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt am Main, Germany
- Institute of Cardiovascular Regeneration, Centre for Molecular Medicine, Goethe University, Frankfurt am Main, Germany
| | - Karl-Ludwig Laugwitz
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany.
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany.
| | - Alessandra Moretti
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany.
- German Center for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany.
- Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany.
- Department of Surgery, Yale University School of Medicine, New Haven, USA.
| | - Alexander Goedel
- First Department of Medicine, Cardiology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany.
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden.
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Zhang Y, Grimwood AL, Hancox JC, Harmer SC, Dempsey CE. Evolutionary coupling analysis guides identification of mistrafficking-sensitive variants in cardiac K + channels: Validation with hERG. Front Pharmacol 2022; 13:1010119. [PMID: 36339618 PMCID: PMC9632996 DOI: 10.3389/fphar.2022.1010119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/30/2022] [Indexed: 09/27/2023] Open
Abstract
Loss of function (LOF) mutations of voltage sensitive K+ channel proteins hERG (Kv11.1) and KCNQ1 (Kv7.1) account for the majority of instances of congenital Long QT Syndrome (cLQTS) with the dominant molecular phenotype being a mistrafficking one resulting from protein misfolding. We explored the use of Evolutionary Coupling (EC) analysis, which identifies evolutionarily conserved pairwise amino acid interactions that may contribute to protein structural stability, to identify regions of the channels susceptible to misfolding mutations. Comparison with published experimental trafficking data for hERG and KCNQ1 showed that the method strongly predicts "scaffolding" regions of the channel membrane domains and has useful predictive power for trafficking phenotypes of individual variants. We identified a region in and around the cytoplasmic S2-S3 loop of the hERG Voltage Sensor Domain (VSD) as susceptible to destabilising mutation, and this was confirmed using a quantitative LI-COR ® based trafficking assay that showed severely attenuated trafficking in eight out of 10 natural hERG VSD variants selected using EC analysis. Our analysis highlights an equivalence in the scaffolding structures of the hERG and KCNQ1 membrane domains. Pathogenic variants of ion channels with an underlying mistrafficking phenotype are likely to be located within similar scaffolding structures that are identifiable by EC analysis.
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Affiliation(s)
- Yihong Zhang
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Amy L. Grimwood
- School of Biological Sciences, Life Sciences Building, Bristol, United Kingdom
| | - Jules C. Hancox
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Stephen C. Harmer
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Christopher E. Dempsey
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
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Du C, Zhang H, Harmer SC, Hancox JC. Identification through action potential clamp of proarrhythmic consequences of the short QT syndrome T618I hERG 'hotspot' mutation. Biochem Biophys Res Commun 2022; 596:49-55. [PMID: 35114584 PMCID: PMC8865743 DOI: 10.1016/j.bbrc.2022.01.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 01/14/2022] [Indexed: 11/30/2022]
Abstract
The T618I KCNH2-encoded hERG mutation is the most frequently observed mutation in genotyped cases of the congenital short QT syndrome (SQTS), a cardiac condition associated with ventricular fibrillation and sudden death. Most T618I hERG carriers exhibit a pronounced U wave on the electrocardiogram and appear vulnerable to ventricular, but not atrial fibrillation (AF). The basis for these effects is unclear. This study used the action potential (AP) voltage clamp technique to determine effects of the T618I mutation on hERG current (IhERG) elicited by APs from different cardiac regions. Whole-cell patch-clamp recordings were made at 37 °C of IhERG from hERG-transfected HEK-293 cells. Maximal IhERG during a ventricular AP command was increased ∼4-fold for T618I IhERG and occurred much earlier during AP repolarization. The mutation also increased peak repolarizing currents elicited by Purkinje fibre (PF) APs. Maximal wild-type (WT) IhERG current during the PF waveform was 87.2 ± 4.5% of maximal ventricular repolarizing current whilst for the T618I mutant, the comparable value was 47.7 ± 2.7%. Thus, the T618I mutation exacerbated differences in repolarizing IhERG between PF and ventricular APs; this could contribute to heterogeneity of ventricular-PF repolarization and consequently to the U waves seen in T618I carriers. The comparatively shorter duration and lack of pronounced plateau of the atrial AP led to a smaller effect of the T618I mutation during the atrial AP, which may help account for the lack of reported AF in T618I carriers. Use of a paired ventricular AP protocol revealed an alteration to protective IhERG transients that affect susceptibility to premature excitation late in AP repolarization/early in diastole. These observations may help explain altered arrhythmia susceptibility in this form of the SQTS. T618I is a ‘hotspot’ hERG potassium channel mutation in the congenital short QT syndrome. Differences in hERG current during ventricular and Purkinje fibre action potentials are exacerbated by the T618I mutation. T618I has more modest effects on current during atrial action potentials. T618I modifies the protective response of hERG to premature ventricular excitation. These alterations to hERG function help explain ECG changes reported in T618I-hERG carriers.
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Affiliation(s)
- Chunyun Du
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Henggui Zhang
- Biological Physics Group, Department of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
| | - Stephen C Harmer
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK; Biological Physics Group, Department of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK.
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8
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Cartwright JH, Aziz Q, Harmer SC, Thayyil S, Tinker A, Munroe PB. Genetic variants in TRPM7 associated with unexplained stillbirth modify ion channel function. Hum Mol Genet 2021; 29:1797-1807. [PMID: 31423533 PMCID: PMC7372550 DOI: 10.1093/hmg/ddz198] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 11/15/2022] Open
Abstract
Stillbirth is the loss of a fetus after 22 weeks of gestation, of which almost half go completely unexplained despite post-mortem. We recently sequenced 35 arrhythmia-associated genes from 70 unexplained stillbirth cases. Our hypothesis was that deleterious mutations in channelopathy genes may have a functional effect in utero that may be pro-arrhythmic in the developing fetus. We observed four heterozygous, nonsynonymous variants in transient receptor potential melastatin 7 (TRPM7), a ubiquitously expressed ion channel known to regulate cardiac development and repolarization in mice. We used site-directed mutagenesis and single-cell patch-clamp to analyze the functional effect of the four stillbirth mutants on TRPM7 ion channel function in heterologous cells. We also used cardiomyocytes derived from human pluripotent stem cells to model the contribution of TRPM7 to action potential morphology. Our results show that two TRPM7 variants, p.G179V and p.T860M, lead to a marked reduction in ion channel conductance. This observation was underpinned by a lack of measurable TRPM7 protein expression, which in the case of p.T860M was due to rapid proteasomal degradation. We also report that human hiPSC-derived cardiomyocytes possess measurable TRPM7 currents; however, siRNA knockdown did not directly affect action potential morphology. TRPM7 variants found in the unexplained stillbirth population adversely affect ion channel function and this may precipitate fatal arrhythmia in utero.
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Affiliation(s)
- James H Cartwright
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Qadeer Aziz
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Stephen C Harmer
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK.,School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, The University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Sudhin Thayyil
- Centre for Perinatal Neuroscience, Imperial College London, London W12OHS, UK
| | - Andrew Tinker
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patricia B Munroe
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
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9
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Rathod V, Harmer SC, Royal A, Aziz Q, Lambiase P, Tinker A. Enhancing mutant IKS channel activity by increasing endogenous PIP2 levels and its interaction with PKA signalling pathway. Europace 2021. [DOI: 10.1093/europace/euab116.543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation
Phosphatidylinositol-4,5-biphosphate (PIP2) is implicated in the regulation and modulation of the IKS channel. The channel is formed at the plasma membrane by the co-assembly of KCNQ1 and KCNE1. Patients with Congenital Long QT 1(LQT1) syndrome are predisposed to Polymorphic VT due to mutations in KCNQ1, leading to impaired channel activity.
We initially transfect Human Embryonic Kidney (HEK) cells with a mammalian vector expressing KCNQ1 gene tagged with green fluorescent protein, along with KCNE1 to form the wild type (WT) IKS channel. The cells were also transfected with a constitutively active PI(4)P 5-kinase(PIP5K), which converts the phospholipid Phosphatidylinositol-4-phosphate to PIP2, therefore increasing endogenous levels of PIP2. To ensure the enzyme remains localised at the plasma membrane we attached it to CFP-FKBP and we co-transfected the cells with Lyn11-FRB construct that tethers to the plasma membrane. When these cells were perfused with Rapamycin it induced chemical dimerization of CF-PIP5K to lyn11. We utilised an inactive PIP5K as a control. Mutants were created with a site directed mutagenesis kit.
In the presence CF-PIP5K, whole cell voltage clamp recordings demonstrated a 2.5 fold statistically significant increase in WT channel activity (at +80mV,p < 0.001), when compared to unaltered PIP2 conditions. Heterozygous Serine566phe and Phe340del mutants had statistically significant reduction in current density compared to wild type in basal conditions. When these mutants were expressed with the active CF-PIP5K, Serine566phe and Phe340 had a 2.97 and 3.30 fold increase in current density, respectively (p <0.05). Homozygous Mutants D242N and T247in also showed statistically significant channel activity.
We substituted serine with alanine at site 27 and 92(S27A/S92A) to generate a mutant known to disrupt cAMP mediated upregulation, there was a statistical 3.3 fold (80 + mV) increase in current density when co-expressed with CF-PIP5K. We then substituted serine with aspartic acid (S27D/S92D) to create a Phosphomimetic mutation, this mutant reproduces the effects of sympathetic mediated augmentation of IKS channel. In the presence of enhanced PIP2 levels, the S27D/S92D failed to demonstrate a statistical increase in current, implying the channel is at its maximum activity and hence we failed to observe any further modulation.
We then proceeded to interrogate how PIP2 interacts with sympathetic signalling system. Pseudojanin(PJ) causes depletion of PIP2 hence perturbing channel activity. When PJ was expressed with KCNQ1 and KCNE1 we observed an 80% reduction in channel activity at +80mV(P <0.001). When we perfused these cells with isoprenaline the channel activity was restored to normal.
Here we illustrate how increasing PIP2 levels can revive IKS channel activity in mutant genotype, therefore supporting evidence of its capabilities as a potential therapeutic tool. This modulation is independent of the PKA-cAMP system. Abstract Figure. Current Increment
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Affiliation(s)
- V Rathod
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
| | - SC Harmer
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
| | - A Royal
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
| | - Q Aziz
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
| | - P Lambiase
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
| | - A Tinker
- Queen Mary University of London, London, United Kingdom of Great Britain & Northern Ireland
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10
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Carpenter A, Chambers OJ, El Harchi A, Bond R, Hanington O, Harmer SC, Hancox JC, James AF. COVID-19 Management and Arrhythmia: Risks and Challenges for Clinicians Treating Patients Affected by SARS-CoV-2. Front Cardiovasc Med 2020; 7:85. [PMID: 32432127 PMCID: PMC7214683 DOI: 10.3389/fcvm.2020.00085] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 04/20/2020] [Indexed: 01/08/2023] Open
Abstract
The COVID-19 pandemic is an unprecedented challenge and will require novel therapeutic strategies. Affected patients are likely to be at risk of arrhythmia due to underlying comorbidities, polypharmacy and the disease process. Importantly, a number of the medications likely to receive significant use can themselves, particularly in combination, be pro-arrhythmic. Drug-induced prolongation of the QT interval is primarily caused by inhibition of the hERG potassium channel either directly and/or by impaired channel trafficking. Concurrent use of multiple hERG-blocking drugs may have a synergistic rather than additive effect which, in addition to any pre-existing polypharmacy, critical illness or electrolyte imbalance, may significantly increase the risk of arrhythmia and Torsades de Pointes. Knowledge of these risks will allow informed decisions regarding appropriate therapeutics and monitoring to keep our patients safe.
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Affiliation(s)
- Alexander Carpenter
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Owen J. Chambers
- Liverpool Heart and Chest Hospital NHS Foundation Trust, Liverpool, United Kingdom
| | - Aziza El Harchi
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Richard Bond
- Gloucestershire Hospitals NHS Foundation Trust, Gloucester, United Kingdom
| | - Oliver Hanington
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Stephen C. Harmer
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Jules C. Hancox
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Andrew F. James
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
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11
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Al-Moubarak E, Zhang Y, Dempsey CE, Zhang H, Harmer SC, Hancox JC. Serine mutation of a conserved threonine in the hERG K + channel S6-pore region leads to loss-of-function through trafficking impairment. Biochem Biophys Res Commun 2020; 526:1085-1091. [PMID: 32321643 PMCID: PMC7237882 DOI: 10.1016/j.bbrc.2020.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/02/2020] [Indexed: 02/06/2023]
Abstract
The human Ether-à-go-go Related Gene (hERG) encodes a potassium channel responsible for the cardiac rapid delayed rectifier K+ current, IKr, which regulates ventricular repolarization. Loss-of-function hERG mutations underpin the LQT2 form of congenital long QT syndrome. This study was undertaken to elucidate the functional consequences of a variant of uncertain significance, T634S, located at a highly conserved position at the top of the S6 helix of the hERG channel. Whole-cell patch-clamp recordings were made at 37 °C of hERG current (IhERG) from HEK 293 cells expressing wild-type (WT) hERG, WT+T634S and hERG-T634S alone. When the T634S mutation was expressed alone little or no IhERG could be recorded. Co-expressing WT and hERG-T634S suppressed IhERG tails by ∼57% compared to WT alone, without significant alteration of voltage dependent activation of IhERG. A similar suppression of IhERG was observed under action potential voltage clamp. Comparable reduction of IKr in a ventricular AP model delayed repolarization and led to action potential prolongation. A LI-COR® based On/In-Cell Western assay showed that cell surface expression of hERG channels in HEK 293 cells was markedly reduced by the T634S mutation, whilst total cellular hERG expression was unaffected, demonstrating impaired trafficking of the hERG-T634S mutant. Incubation with E−4031, but not lumacaftor, rescued defective hERG-T634S channel trafficking and IhERG density. In conclusion, these data identify hERG-T634S as a rescuable trafficking defective mutation that reduces IKr sufficiently to delay repolarization and, thereby, potentially produce a LQT2 phenotype. hERG potassium channel variants can cause dangerous ventricular arrhythmias. An S6 helix threonine in hERG, T634, is highly conserved amongst potassium channels. The T634S mutation reduces hERG current and its contribution to ventricular repolarization. The T634S mutation decreases hERG channel surface expression but not synthesis. T634S-induced hERG trafficking impairment is pharmacologically rescuable.
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Affiliation(s)
- Ehab Al-Moubarak
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Yihong Zhang
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Christopher E Dempsey
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
| | - Stephen C Harmer
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
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12
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Mosqueira D, Mannhardt I, Bhagwan JR, Lis-Slimak K, Katili P, Scott E, Hassan M, Prondzynski M, Harmer SC, Tinker A, Smith JGW, Carrier L, Williams PM, Gaffney D, Eschenhagen T, Hansen A, Denning C. CRISPR/Cas9 editing in human pluripotent stem cell-cardiomyocytes highlights arrhythmias, hypocontractility, and energy depletion as potential therapeutic targets for hypertrophic cardiomyopathy. Eur Heart J 2019; 39:3879-3892. [PMID: 29741611 PMCID: PMC6234851 DOI: 10.1093/eurheartj/ehy249] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/11/2018] [Indexed: 12/26/2022] Open
Abstract
Aims Sarcomeric gene mutations frequently underlie hypertrophic cardiomyopathy (HCM), a prevalent and complex condition leading to left ventricle thickening and heart dysfunction. We evaluated isogenic genome-edited human pluripotent stem cell-cardiomyocytes (hPSC-CM) for their validity to model, and add clarity to, HCM. Methods and results CRISPR/Cas9 editing produced 11 variants of the HCM-causing mutation c.C9123T-MYH7 [(p.R453C-β-myosin heavy chain (MHC)] in 3 independent hPSC lines. Isogenic sets were differentiated to hPSC-CMs for high-throughput, non-subjective molecular and functional assessment using 12 approaches in 2D monolayers and/or 3D engineered heart tissues. Although immature, edited hPSC-CMs exhibited the main hallmarks of HCM (hypertrophy, multi-nucleation, hypertrophic marker expression, sarcomeric disarray). Functional evaluation supported the energy depletion model due to higher metabolic respiration activity, accompanied by abnormalities in calcium handling, arrhythmias, and contraction force. Partial phenotypic rescue was achieved with ranolazine but not omecamtiv mecarbil, while RNAseq highlighted potentially novel molecular targets. Conclusion Our holistic and comprehensive approach showed that energy depletion affected core cardiomyocyte functionality. The engineered R453C-βMHC-mutation triggered compensatory responses in hPSC-CMs, causing increased ATP production and αMHC to energy-efficient βMHC switching. We showed that pharmacological rescue of arrhythmias was possible, while MHY7: MYH6 and mutant: wild-type MYH7 ratios may be diagnostic, and previously undescribed lncRNAs and gene modifiers are suggestive of new mechanisms. ![]()
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Affiliation(s)
- Diogo Mosqueira
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Partner Site Hamburg/Kiel/Lübeck, DZHK (German Center for Cardiovascular Research), Hamburg, Germany
| | - Jamie R Bhagwan
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Katarzyna Lis-Slimak
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Puspita Katili
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Elizabeth Scott
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Mustafa Hassan
- The Heart Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London, UK
| | - Maksymilian Prondzynski
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Partner Site Hamburg/Kiel/Lübeck, DZHK (German Center for Cardiovascular Research), Hamburg, Germany
| | - Stephen C Harmer
- The Heart Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London, UK
| | - Andrew Tinker
- The Heart Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London, UK
| | - James G W Smith
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
| | - Lucie Carrier
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Partner Site Hamburg/Kiel/Lübeck, DZHK (German Center for Cardiovascular Research), Hamburg, Germany
| | - Philip M Williams
- Molecular Therapeutics and Formulation. School of Pharmacy, University of Nottingham, UK
| | - Daniel Gaffney
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Partner Site Hamburg/Kiel/Lübeck, DZHK (German Center for Cardiovascular Research), Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Partner Site Hamburg/Kiel/Lübeck, DZHK (German Center for Cardiovascular Research), Hamburg, Germany
| | - Chris Denning
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, UK
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13
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Zhou X, Bueno-Orovio A, Schilling RJ, Kirkby C, Denning C, Rajamohan D, Burrage K, Tinker A, Rodriguez B, Harmer SC. Investigating the Complex Arrhythmic Phenotype Caused by the Gain-of-Function Mutation KCNQ1-G229D. Front Physiol 2019; 10:259. [PMID: 30967788 PMCID: PMC6430739 DOI: 10.3389/fphys.2019.00259] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/28/2019] [Indexed: 12/18/2022] Open
Abstract
The congenital long QT syndrome (LQTS) is a cardiac electrophysiological disorder that can cause sudden cardiac death. LQT1 is a subtype of LQTS caused by mutations in KCNQ1, affecting the slow delayed-rectifier potassium current (I Ks), which is essential for cardiac repolarization. Paradoxically, gain-of-function mutations in KCNQ1 have been reported to cause borderline QT prolongation, atrial fibrillation (AF), sinus bradycardia, and sudden death, however, the mechanisms are not well understood. The goal of the study is to investigate the ionic, cellular and tissue mechanisms underlying the complex phenotype of a gain-of-function mutation in KCNQ1, c.686G > A (p.G229D) using computer modeling and simulations informed by in vitro measurements. Previous studies have shown this mutation to cause AF and borderline QT prolongation. We report a clinical description of a family that carry this mutation and that a member of the family died suddenly during sleep at 21 years old. Using patch-clamp experiments, we confirm that KCNQ1-G229D causes a significant gain in channel function. We introduce the effect of the mutation in populations of atrial, ventricular and sinus node (SN) cell models to investigate mechanisms underlying phenotypic variability. In a population of human atrial and ventricular cell models and tissue, the presence of KCNQ1-G229D predominantly shortens atrial action potential duration (APD). However, in a subset of models, KCNQ1-G229D can act to prolong ventricular APD by up to 7% (19 ms) and underlie depolarization abnormalities, which could promote QT prolongation and conduction delays. Interestingly, APD prolongations were predominantly seen at slow pacing cycle lengths (CL > 1,000 ms), which suggests a greater arrhythmic risk during bradycardia, and is consistent with the observed sudden death during sleep. In a population of human SN cell models, the KCNQ1-G229D mutation results in slow/abnormal sinus rhythm, and we identify that a stronger L-type calcium current enables the SN to be more robust to the mutation. In conclusion, our computational modeling experiments provide novel mechanistic explanations for the observed borderline QT prolongation, and predict that KCNQ1-G229D could underlie SN dysfunction and conduction delays. The mechanisms revealed in the study can potentially inform management and treatment of KCNQ1 gain-of-function mutation carriers.
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Affiliation(s)
- Xin Zhou
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Alfonso Bueno-Orovio
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | | | | | - Chris Denning
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Divya Rajamohan
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Kevin Burrage
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
- Australian Research Council Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, QLD, Australia
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Andrew Tinker
- The William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Stephen C. Harmer
- The William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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14
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Rathod VS, Harmer SC, Salsbury GA, Bitner-Glindzicz M, Lambiase PD, Tinker A. P449The novel long QT syndrome type 1 mutation KCNQ1-p.Thr247dup causes severe channel dysfunction but retains preserved adrenergic regulation. Europace 2018. [DOI: 10.1093/europace/euy015.258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- V S Rathod
- Queen Mary University of London, Cardiac Electrophysiology, London, United Kingdom
| | - S C Harmer
- Queen Mary University of London, Cardiac Electrophysiology, London, United Kingdom
| | - G A Salsbury
- Queen Mary University of London, Cardiac Electrophysiology, London, United Kingdom
| | - M Bitner-Glindzicz
- University College London, UCL GOS Institute of Child Health, London, United Kingdom
| | | | - A Tinker
- Queen Mary University of London, Cardiac Electrophysiology, London, United Kingdom
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15
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Munroe PB, Addison S, Abrams DJ, Sebire NJ, Cartwright J, Donaldson I, Cohen MM, Mein C, Tinker A, Harmer SC, Aziz Q, Terry A, Struebig M, Warren HR, Vadgama B, Fowler DJ, Peebles D, Taylor AM, Lally PJ, Thayyil S. Postmortem Genetic Testing for Cardiac Ion Channelopathies in Stillbirths. Circ Genom Precis Med 2018; 11:e001817. [PMID: 29874177 DOI: 10.1161/circgen.117.001817] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 11/07/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Although stillbirth is a significant health problem worldwide, the definitive cause of death remains elusive in many cases, despite detailed autopsy. In this study of partly explained and unexplained stillbirths, we used next-generation sequencing to examine an extended panel of 35 candidate genes known to be associated with ion channel disorders and sudden cardiac death. METHODS AND RESULTS We examined tissue from 242 stillbirths (≥22 weeks), including those where no definite cause of death could be confirmed after a full autopsy. We obtained high-quality DNA from 70 cases, which were then sequenced for a custom panel of 35 genes, 12 for inherited long- and short-QT syndrome genes (LQT1-LQT12 and SQT1-3), and 23 additional candidate genes derived from genome-wide association studies. We examined the functional significance of a selected variant by patch-clamp electrophysiological recording. No predicted damaging variants were identified in KCNQ1 (LQT1) or KCNH2 (LQT2). A rare putative pathogenic variant was found in KCNJ2(LQT7) in 1 case, and several novel variants of uncertain significance were observed. The KCNJ2 variant (p. R40Q), when assessed by whole-cell patch clamp, affected the function of the channel. There was no significant evidence of enrichment of rare predicted damaging variants within any of the candidate genes. CONCLUSIONS Although a causative link is unclear, 1 putative pathogenic and variants of uncertain significance variant resulting in cardiac channelopathies was identified in some cases of otherwise unexplained stillbirth, and these variants may have a role in fetal demise. CLINICAL TRIAL REGISTRATION URL: https://www.clinicaltrials.gov. Unique identifier: NCT01120886.
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Affiliation(s)
- Patricia B Munroe
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.).
| | - Shea Addison
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Dominic J Abrams
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Neil J Sebire
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - James Cartwright
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Ian Donaldson
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Marta M Cohen
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Charles Mein
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Andrew Tinker
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Stephen C Harmer
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Qadeer Aziz
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Anna Terry
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Monika Struebig
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Helen R Warren
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Bhumita Vadgama
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Darren J Fowler
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Donald Peebles
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Andrew M Taylor
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Peter J Lally
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.)
| | - Sudhin Thayyil
- From the Clinical Pharmacology (P.B.M., S.A., J.C., A.T., S.C.H., Q.A., H.R.W.) and National Institute for Health Research Barts Cardiovascular Biomedical Research Unit (P.B.M., A.T., H.R.W.), William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, United Kingdom; Genome Centre, Queen Mary University of London, United Kingdom (I.D., C.M., A.T., M.S., B.V.); Centre for Perinatal Neuroscience, Imperial College London, United Kingdom (S.A., P.J.L., S.T.); Paediatric Cardiology, Children's Hospital Boston, MA (D.J.A.); Histopathology, Great Ormond Street Hospital, London, United Kingdom (N.J.S.); Histopathology, Sheffield Children's Hospital, United Kingdom (M.M.C.); Histopathology, Southampton General Hospital, United Kingdom (D.J.F.); Institute for Women's Health, San Antonio, TX (D.P.); and Institute for Cardiovascular Science, University College London, United Kingdom (A.M.T.).
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16
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Miller DC, Harmer SC, Poliandri A, Nobles M, Edwards EC, Ware JS, Sharp TV, McKay TR, Dunkel L, Lambiase PD, Tinker A. Ajmaline blocks I Na and I Kr without eliciting differences between Brugada syndrome patient and control human pluripotent stem cell-derived cardiac clusters. Stem Cell Res 2017; 25:233-244. [PMID: 29172153 PMCID: PMC5727153 DOI: 10.1016/j.scr.2017.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 10/09/2017] [Accepted: 11/03/2017] [Indexed: 12/14/2022] Open
Abstract
The class Ia anti-arrhythmic drug ajmaline is used clinically to unmask latent type I ECG in Brugada syndrome (BrS) patients, although its mode of action is poorly characterised. Our aims were to identify ajmaline's mode of action in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs), and establish a simple BrS hiPSC platform to test whether differences in ajmaline response could be determined between BrS patients and controls. Control hiPSCs were differentiated into spontaneously contracting cardiac clusters. It was found using multi electrode array (MEA) that ajmaline treatment significantly lengthened cluster activation-recovery interval. Patch clamping of single CMs isolated from clusters revealed that ajmaline can block both INa and IKr. Following generation of hiPSC lines from BrS patients (absent of pathogenic SCN5A sodium channel mutations), analysis of hiPSC-CMs from patients and controls revealed that differentiation and action potential parameters were similar. Comparison of cardiac clusters by MEA showed that ajmaline lengthened activation-recovery interval consistently across all lines. We conclude that ajmaline can block both depolarisation and repolarisation of hiPSC-CMs at the cellular level, but that a more refined integrated tissue model may be necessary to elicit differences in its effect between BrS patients and controls. hiPSC lines generated and differentiated from BrS patients lacking SCN5A mutations Ajmaline lengthens the activation-recovery interval of hPSC cardiac clusters Ajmaline effect consistent between BrS patient and control hPSC cardiac clusters Patch clamp analysis of hiPSC-CMs reveals ajmaline blocks both INa and IKr
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Affiliation(s)
- Duncan C Miller
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK; Barts Cancer Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Stephen C Harmer
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Ariel Poliandri
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Muriel Nobles
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Elizabeth C Edwards
- National Heart and Lung Institute, NIHR Royal Brompton Cardiovascular BRU, Imperial College London, London, UK
| | - James S Ware
- National Heart and Lung Institute, NIHR Royal Brompton Cardiovascular BRU, Imperial College London, London, UK
| | - Tyson V Sharp
- Barts Cancer Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Tristan R McKay
- School of Healthcare Science, Manchester Metropolitan University, Manchester, UK
| | - Leo Dunkel
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, UCL and Barts Heart Centre, London, UK
| | - Andrew Tinker
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
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17
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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] [What about the content of this article? (0)] [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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18
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Abstract
Central to the genesis of ventricular cardiac arrhythmia are variations in determinants of excitability. These involve individual ionic channels and transporters in cardiac myocytes but also tissue factors such as variable conduction of the excitation wave, fibrosis and source-sink mismatch. It is also known that in certain diseases and particularly the channelopathies critical events occur with specific stressors. For example, in hereditary long QT syndrome due to mutations in KCNQ1 arrhythmic episodes are provoked by exercise and in particular swimming. Thus not only is the static substrate important but also how this is modified by dynamic signalling events associated with common physiological responses. In this review, we examine the regulation of ventricular excitability by signalling pathways from a cellular and tissue perspective in an effort to identify key processes, effectors and potential therapeutic approaches. We specifically focus on the autonomic nervous system and related signalling pathways.
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Affiliation(s)
- Malcolm Finlay
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK
| | - Stephen C Harmer
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK
| | - Andrew Tinker
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK.
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19
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Nessa A, Aziz QH, Thomas AM, Harmer SC, Tinker A, Hussain K. Molecular mechanisms of congenital hyperinsulinism due to autosomal dominant mutations in ABCC8. Hum Mol Genet 2015; 24:5142-53. [PMID: 26092864 DOI: 10.1093/hmg/ddv233] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 06/16/2015] [Indexed: 11/12/2022] Open
Abstract
Congenital Hyperinsulinism (CHI) is a rare heterogeneous disease characterized by unregulated insulin secretion. Dominant mutations in ABCC8 causing medically unresponsive CHI have been reported; however, the molecular mechanisms are not clear. The molecular basis of medically unresponsive CHI due to dominant ABCC8 mutations has been studied in 10 patients, who were medically unresponsive to diazoxide (DZX), and nine of whom required a near-total pancreatectomy, and one partial pancreatectomy. DNA sequencing revealed seven dominant inactivating heterozygous missense mutations in ABCC8, including one novel and six previously reported but uncharacterized mutations. Two groups of mutations with different cellular mechanisms were characterized. Mutations in the transmembrane domain (TMD) were more responsive to channel activators such as DZX, MgADP and metabolic inhibition. The trafficking analysis has shown that nucleotide-binding domain two (NBD2) mutations are not retained in the endoplasmic reticulum (ER) and are present on the membrane. However, the TMD mutations were retained in the ER. D1506E was the most severe SUR1-NBD2 mutation. Homologous expression of D1506E revealed a near absence of KATP currents in the presence of DZX and intracellular MgADP. Heterozygous expression of D1506E showed a strong dominant-negative effect on SUR1\Kir6.2 currents. Overall, we define two groups of mutation with different cellular mechanisms. In the first group, channel complexes with mutations in NBD2 of SUR1 traffic normally but are unable to be activated by MgADP. In the second group, channels mutations in the TMD of SUR1 are retained in the ER and have variable functional impairment.
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Affiliation(s)
- Azizun Nessa
- Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, UK
| | - Qadeer H Aziz
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK and
| | - Alison M Thomas
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK and
| | - Stephen C Harmer
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK and
| | - Andrew Tinker
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK and
| | - Khalid Hussain
- Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, UK, Genetics and Genomic Medicine, UCL Institute of Child Health, London Centre for Paediatric Endocrinology and Metabolism, Great Ormond Street Hospital for Children NHS, London WC1N 1EH, UK
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Telezhkin V, Thomas AM, Harmer SC, Tinker A, Brown DA. A basic residue in the proximal C-terminus is necessary for efficient activation of the M-channel subunit Kv7.2 by PI(4,5)P₂. Pflugers Arch 2013; 465:945-53. [PMID: 23291709 PMCID: PMC3696465 DOI: 10.1007/s00424-012-1199-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/03/2012] [Accepted: 12/03/2012] [Indexed: 12/01/2022]
Abstract
All Kv7 potassium channels require membrane phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) for their normal function and hence can be physiologically regulated by neurotransmitters and hormones that stimulate phosphoinositide hydrolysis. Recent mutational analysis indicates that a cluster of basic residues in the proximal C-terminus (K354/K358/R360/K362) is crucial for PI(4,5)P2 activation of cardiac Kv7.1 channels. Since this cluster is largely conserved in all Kv7 subunits, we tested whether homologous residues are also required for activation of Kv7.2 (a subunit of neuronal M-channels). We found that the mutation Kv7.2 (R325A) (corresponding to R360 in Kv7.1) reduced Kv7.2 current amplitude by ∼60 % (P < 0.02) without change in voltage sensitivity and reduced the sensitivity of Kv7.2 channels to dioctanoyl-phosphatidylinositol-4,5-bisphosphate by ∼eightfold (P < 0.001). Taking into account previous experiments (Zhang et al., Neuron 37:963-75, 2003) implicating Kv7.2 (H328), and since R325 and H328 are conserved in homologous positions in all other Kv7 channels, we suggest that this proximal C-terminal domain adjacent to the last transmembrane domain that contains R325 and H328 (in Kv7.2) might play a major role in the activation of all members of the Kv7 channel family by PI(4,5)P2.
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Affiliation(s)
- Vsevolod Telezhkin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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22
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Abstract
The KCNQ family of potassium channels underlie a repolarizing K(+) current in the heart and the M-current in neurones. The assembly of KCNQ1 with KCNE1 generates the delayed rectifier current I(Ks) in the heart. Characteristically these channels are regulated via G(q/11)-coupled receptors and the inhibition seen after phospholipase C activation is now thought to occur from membrane phosphatidylinositol (4,5)-bisphosphate (PIP(2)) depletion. It is not clear how KCNQ1 recognizes PIP(2) and specifically which residues in the channel complex are important. Using biochemical techniques we identify a cluster of basic residues namely, Lys-354, Lys-358, Arg-360, and Lys-362, in the proximal C terminus as being involved in binding anionic phospholipids. The mutation of specific residues in combination, to alanine leads to the loss of binding to phosphoinositides. Functionally, the introduction of these mutations into KCNQ1 leads to shifts in the voltage dependence of channel activation toward depolarized potentials and reductions in current density. Additionally, the biophysical effects of the charge neutralizing mutations, which disrupt phosphoinositide binding, mirror the effects we see on channel function when we deplete cellular PIP(2) levels through activation of a G(q/11)-coupled receptor. Conversely, the addition of diC8-PIP(2) to the wild-type channel, but not a PIP(2) binding-deficient mutant, acts to shift the voltage dependence of channel activation toward hyperpolarized potentials and increase current density. In conclusion, we use a combined biochemical and functional approach to identify a cluster of basic residues important for the binding and action of anionic phospholipids on the KCNQ1/KCNE1 complex.
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Affiliation(s)
- Alison M Thomas
- Department of Medicine, University College London, 5 University Street, London WC1E 6JJ, United Kingdom
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23
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Mashanov GI, Nobles M, Harmer SC, Molloy JE, Tinker A. Direct observation of individual KCNQ1 potassium channels reveals their distinctive diffusive behavior. J Biol Chem 2009; 285:3664-3675. [PMID: 19940153 DOI: 10.1074/jbc.m109.039974] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have directly observed the trafficking and fusion of ion channel containing vesicles and monitored the release of individual ion channels at the plasma membrane of live mammalian cells using total internal reflection fluorescence microscopy. Proteins were fused in-frame with green or red fluorescent proteins and expressed at low level in HL-1 and HEK293 cells. Dual color imaging revealed that vesicle trafficking involved motorized movement along microtubules followed by stalling, fusion, and subsequent release of individual ion channels at the plasma membrane. We found that KCNQ1-KCNE1 complexes were released in batches of about 5 molecules per vesicle. To elucidate the properties of ion channel complexes at the cell membrane we tracked the movement of individual molecules and compared the diffusive behavior of two types of potassium channel complex (KCNQ1-KCNE1 and Kir6.2-SUR2A) to that of a G-protein coupled receptor, the A1 adenosine receptor. Plots of mean squared displacement against time intervals showed that mobility depended on channel type, cell type, and temperature. Analysis of the mobility of wild type KCNQ1-KCNE1 complexes showed the existence of a significant immobile subpopulation and also a significant number of molecules that demonstrated periodic stalling of diffusive movements. This behavior was enhanced in cells treated with jasplakinolide and was abrogated in a C-terminal truncated form (KCNQ1(R518X)-KCNE1) of the protein. This mutant has been identified in patients with the long QT syndrome. We propose that KCNQ1-KCNE1 complexes interact intermittently with the actin cytoskeleton via the C-terminal region and this interaction may have a functional role.
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Affiliation(s)
- Gregory I Mashanov
- From the Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA and
| | - Muriel Nobles
- the BHF Laboratories and Department of Medicine, University College London, 5 University Street, London WC1E 6JJ, United Kingdom
| | - Stephen C Harmer
- the BHF Laboratories and Department of Medicine, University College London, 5 University Street, London WC1E 6JJ, United Kingdom
| | - Justin E Molloy
- From the Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA and.
| | - Andrew Tinker
- the BHF Laboratories and Department of Medicine, University College London, 5 University Street, London WC1E 6JJ, United Kingdom.
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Abstract
KCNE1 associates with the pore-forming alpha-subunit KCNQ1 to generate the slow (I(Ks)) current in cardiac myocytes. Mutations in either KCNQ1 or KCNE1 can alter the biophysical properties of I(Ks) and mutations in KCNE1 underlie cases of long QT syndrome type 5 (LQT5). We previously investigated a mutation in KCNE1, T58P/L59P, which causes severe attenuation of I(Ks). However, how T58P/L59P acts to disrupt I(Ks) has not been determined. In this study, we investigate and compare the effects of T58P/L59P with three other LQT5 mutations (G52R, S74L, and R98W) on the biophysical properties of the current, trafficking of KCNQ1, and assembly of the I(Ks) channel. G52R and T58P/L59P produce currents that lack the kinetic behavior of I(Ks). In contrast, S74L and R98W both produce I(Ks)-like currents but with rightward shifted voltage dependence of activation. All of the LQT5 mutants express protein robustly, and T58P/L59P and R98W cause modest, but significant, defects in the trafficking of KCNQ1. Despite defects in trafficking, in the presence of KCNQ1, T58P/L59P and the other LQT5 mutants are present at the plasma membrane. Interestingly, in comparison to KCNE1 and the other LQT5 mutants, T58P/L59P associates only weakly with KCNQ1. In conclusion, we identify the disease mechanisms for each mutation and reveal that T58P/L59P causes disease through a novel mechanism that involves defective I(Ks) complex assembly.
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Affiliation(s)
- Stephen C Harmer
- Department of Medicine, University College London, London, WC1E 6JJ, UK
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Bicknell KA, Harmer SC, Yiangson S, Lockwood W, Bicknell AB. Lys-gamma3-MSH: a global regulator of hormone sensitive lipase activity? Mol Cell Endocrinol 2009; 300:71-6. [PMID: 18977407 DOI: 10.1016/j.mce.2008.09.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 09/23/2008] [Accepted: 09/23/2008] [Indexed: 11/18/2022]
Abstract
Gamma-melanocyte stimulating hormone (gamma-MSH) is a peptide derived from the ACTH precursor, pro-opiomelanocortin (POMC), and belongs to a family of peptides called the melanocortins that also comprises alpha- and beta-MSH. Although conserved in tetrapods, the biological role of gamma-MSH remains largely undefined. It has been demonstrated previously that gamma-MSH is involved in the regulating the activity of hormone sensitive lipase (HSL) activity in the adrenal and more recently, in the adipocyte. It has been shown also to have effects on the cardiovascular and renal systems. This short review will provide a brief overview of the role of gamma-MSH in the adrenal and the more recent report that it can also regulate HSL function in the adipocyte. We also present some preliminary data purporting a direct role for Lys-gamma(3)-MSH in the regulation of HSL phosphorylation in the heart. Taken together these data suggest that gamma-MSH peptides might play a more widespread role in lipid and cholesterol utilization.
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Affiliation(s)
- Katrina A Bicknell
- School of Pharmacy, The University of Reading, Whiteknights, PO Box 228, Reading, Berkshire, RG6 6AJ, UK
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26
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Abstract
Lys-gamma3-MSH is a melanocortin peptide derived from the C-terminal of the 16 kDa fragment of POMC. The physiological role of Lys-gamma3-MSH is unclear, although it has previously been shown that, although not directly steroidogenic, it can act to potentiate the steroidogenic response of adrenal cortical cells to ACTH. This synergistic effect appears to be correlated with an ability to increase the activity of hormone sensitive lipase (HSL) and therefore the rate of cholesterol ester hydrolysis. Ligand binding studies have suggested that high-affinity binding sites for Lys-gamma3-MSH exist in the adrenal gland and a number of other rat tissues that express HSL, including adipose, skeletal muscle and testes. To investigate the hypothesis that Lys-gamma3-MSH may play a wider role in cholesterol and lipid metabolism, we tested the effect of Lys-gamma3-MSH on lipolysis, an HSL-mediated process, in 3T3-L1 adipocytes. In comparison with other melanocortin peptides, Lys-gamma3-MSH was found to be a potent stimulator of lipolysis. It was also able to phosphorylate HSL at key serine residues and stimulate the hyperphosphorylation of perilipin A. The receptor through which the lipolytic actions of Lys-gamma3-MSH are being mediated is not clear. Attempts to characterise this receptor suggest that either the pharmacology of the melanocortin receptor 5 in 3T3-L1 adipocytes is different from that described when expressed in heterologous systems or the possibility that a further, as yet uncharacterised, receptor exists.
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Affiliation(s)
- Stephen C Harmer
- School of Biological Sciences, The University of ReadingWhiteknights, PO Box 228, Reading, Berkshire RG6 6AJUK
| | - David J Pepper
- School of Biological Sciences, The University of ReadingWhiteknights, PO Box 228, Reading, Berkshire RG6 6AJUK
| | - Katy Cooke
- School of Biological Sciences, The University of ReadingWhiteknights, PO Box 228, Reading, Berkshire RG6 6AJUK
| | - Hugh P J Bennett
- Endocrine Laboratory, Royal Victoria Hospital687 Pine Avenue West, Montreal, Quebec H3A1A1Canada
| | - Andrew B Bicknell
- School of Biological Sciences, The University of ReadingWhiteknights, PO Box 228, Reading, Berkshire RG6 6AJUK
- (Correspondence should be addressed to A B Bicknell; )
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27
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Abstract
Alpha-, beta- and gamma-melanocyte stimulating hormones (MSHs) are peptides derived from the ACTH precursor, pro-opiomelanocortin. All three peptides have been highly conserved throughout evolution but their exact biological function in mammals is still largely obscure. In recent years, there has been a surge of interest in alpha-MSH and its role in the regulation of feeding. Gamma-MSH by contrast has been shown to be involved in the regulation of adrenal steroidogenesis and also has effects on the cardiovascular and renal systems. This review will provide an overview of the role that gamma-MSH peptides play in the regulation of adrenal steroidogenesis.
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Affiliation(s)
- Stephen C Harmer
- School of Animal and Microbial Sciences, The University of Reading, Whiteknights, P.O. Box 228, Reading, Berkshire RG6 6AJ, UK
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28
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Abstract
The pro-opiomelanocortin (POMC)-derived peptides, pro-gamma-MSH (16K fragment), and Lys-gamma3-MSH, have been shown to potentiate the steroidogenic action of corticotrophin (ACTH) on the adrenal cortex. Using a continuously perfused adrenal cell column system, we have tested the hypothesis that gamma-MSH peptides exert their effect through the Melanocortin 3 Receptor (MC3-R), since this is the only known receptor to have high affinity for gamma-MSH peptides and has been suggested to be expressed in the rat adrenal. To investigate this hypothesis we tested whether the MC3-R agonist MTII and antagonist SHU9119 could mimic or block the actions of pro-gamma-MSH. We found that MTII could not mimic, and SHU9119 could not block pro-gamma-MSH mediated potentiation of ACTH-induced steroidogenesis. These results suggest that the MC3-R is not involved in mediating the potentiation effect, adding further evidence to the argument that another melanocortin receptor exists.
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Affiliation(s)
- Stephen C Harmer
- School of Animal and Microbial Sciences, The University of Reading, Reading, Berkshire, UK
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