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Kim M, Das S, Tester DJ, Pradhananga S, Hamrick SK, Gao X, Srinivasan D, Sager PT, Ackerman MJ. SGK1 Inhibition Attenuated the Action Potential Duration in Patient- and Genotype-Specific Re-Engineered Heart Cells with Congenital Long QT Syndrome. Heart Rhythm O2 2023; 4:268-274. [PMID: 37124559 PMCID: PMC10134391 DOI: 10.1016/j.hroo.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 02/14/2023] [Indexed: 02/17/2023] Open
Abstract
Background Long QT syndrome (LQTS) stems from pathogenic variants in KCNQ1 (LQT1), KCNH2 (LQT2), or SCN5A (LQT3) and is characterized by action potential duration (APD) prolongation. Inhibition of serum and glucocorticoid regulated kinase-1 (SGK1) is proposed as a novel therapeutic for LQTS. Objective The study sought to test the efficacy of novel, selective SGK1 inhibitors in induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) models of LQTS. Methods The mexiletine (MEX)-sensitive SCN5A-P1332L iPSC-CMs were tested initially compared with a CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 SCN5A-P1332L variant-corrected isogenic control (IC). The SGK1-I1 therapeutic efficacy, compared with MEX, was tested for APD at 90% repolarization (APD90) shortening in SCN5A-P1332L, SCN5A-R1623Q, KCNH2-G604S, and KCNQ1-V254M iPSC-CMs using FluoVolt. Results The APD90 was prolonged in SCN5A-P1332L iPSC-CMs compared with its IC (646 ± 7 ms vs 482 ± 23 ms; P < .0001). MEX shortened the APD90 to 560 ± 7 ms (52% attenuation, P < .0001). SGK1-I1 shortened the APD90 to 518 ± 5 ms (78% attenuation, P < .0001) but did not shorten the APD90 in the IC. SGK1-I1 shortened the APD90 of the SCN5A-R1623Q iPSC-CMs (753 ± 8 ms to 475 ± 19 ms compared with 558 ± 19 ms with MEX), the KCNH2-G604S iPSC-CMs (666 ± 10 ms to 574 ± 18 ms vs 538 ± 15 ms after MEX), and the KCNQ1-V254M iPSC-CMs (544 ± 10 ms to 475 ± 11ms; P = .0004). Conclusions Therapeutically inhibiting SGK1 effectively shortens the APD in human iPSC-CM models of the 3 major LQTS genotypes. These preclinical data support development of SGK1 inhibitors as novel, first-in-class therapy for patients with congenital LQTS.
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Ye D, Zhou W, Hamrick SK, Tester DJ, Kim CSJ, Barajas-Martinez H, Hu D, Giudicessi JR, Antzelevitch C, Ackerman MJ. Acacetin, a Potent Transient Outward Current Blocker, May Be a Novel Therapeutic for KCND3-Encoded Kv4.3 Gain-of-Function-Associated J-Wave Syndromes. Circ Genom Precis Med 2022; 15:e003238. [PMID: 35861988 PMCID: PMC9588492 DOI: 10.1161/circgen.120.003238] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/18/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND The transient outward current (Ito) that mediates early (phase 1) repolarization is conducted by the KCND3-encoded Kv4.3 pore-forming α-subunit. KCND3 gain-of-function mutations have been reported previously as a pathogenic substrate for J wave syndromes (JWS), including the Brugada syndrome and early repolarization syndrome, as well as autopsy-negative sudden unexplained death (SUD). Acacetin, a natural flavone, is a potent Ito current blocker. Acacetin may be a novel therapeutic for KCND3-mediated J wave syndrome. METHODS KCND3-V392I was identified in an 18-year-old male with J wave syndrome/early repolarization syndrome, and a history of cardiac arrest including ventricular tachycardia/ventricular fibrillation and atrial fibrillation/atrial flutter. Pathogenic KCND3 mutation was engineered by site-directed mutagenesis and co-expressed with wild-type KChIP2 in TSA201 cells. Gene-edited/variant-corrected isogenic control and patient-specific pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from the p. Val392Ile-KCND3-positive patient were generated. Ito currents and action potentials were recorded before and after treatment with Acacetin using the whole cell patch-clamp and multielectrode array technique. Western blot and immunocytochemistry were performed to investigate KCND3 expression. RESULTS KCND3-V392I demonstrated a marked gain-of-function phenotype, increasing peak Ito current density by 92.2% (P<0.05 versus KCND3-WT). KCND3 expression was significantly increased in KCND3-V392I-derived iPSC-CMs (P<0.05 versus isogenic control). While KCND3-WT revealed an IC50 of 7.2±1.0 µmol/L for acacetin effect, 30 µmol/L acacetin dramatically inhibited KCND3-V392I peak Ito current density by 96.2% (P<0.05 versus before Acacetin). Ito was also increased by 60.9% in Kv4.3-V392I iPSC-CM (P<0.05 versus isogenic control iPSC-CM). Ten micromoles per liter acacetin, a concentration approaching its IC50 value, inhibited Ito by ≈50% in patient-derived iPSC-CMs and reduced the accentuated action potential notch displayed in KCND3-V392I-derived iPSC-CMs. CONCLUSIONS This preclinical study provides pharmacological and functional evidence to suggest that Acacetin may be a novel therapeutic for patients with KCND3 gain-of-function-associated J wave syndrome by inhibiting Ito and abolishing the accentuated action potential notch in patient-derived iPSC-CMs.
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Affiliation(s)
- Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | - Wei Zhou
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | - Samantha K. Hamrick
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | - David J Tester
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | - CS John Kim
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | | | - Dan Hu
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
| | - John R. Giudicessi
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | | | - Michael J. Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory); Department of Cardiovascular Medicine/Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic); Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
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Stutzman MJ, Kim CSJ, Tester DJ, Hamrick SK, Dotzler SM, Giudicessi JR, Miotto MC, Gc JB, Frank J, Marks AR, Ackerman MJ. Characterization of N-terminal RYR2 variants outside CPVT1 hotspot regions using patient iPSCs reveal pathogenesis and therapeutic potential. Stem Cell Reports 2022; 17:2023-2036. [PMID: 35931078 PMCID: PMC9481874 DOI: 10.1016/j.stemcr.2022.07.002] [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: 12/30/2021] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 11/18/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a cardiac channelopathy causing ventricular tachycardia following adrenergic stimulation. Pathogenic variants in RYR2-encoded ryanodine receptor 2 (RYR2) cause CPVT1 and cluster into domains I–IV, with the most N-terminal domain involving residues 77–466. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated for RYR2-F13L, -L14P, -R15P, and -R176Q variants. Isogenic control iPSCs were generated using CRISPR-Cas9/PiggyBac. Fluo-4 Ca2+ imaging assessed Ca2+ handling with/without isoproterenol (ISO), nadolol (Nad), and flecainide (Flec) treatment. CPVT1 iPSC-CMs displayed increased Ca2+ sparking and Ca2+ transient amplitude following ISO compared with control. Combined Nad treatment/ISO stimulation reduced Ca2+ amplitude and sparking in variant iPSC-CMs. Molecular dynamic simulations visualized the structural role of these variants. We provide the first functional evidence that these most proximal N-terminal localizing variants alter calcium handling similar to CPVT1. These variants are located at the N-terminal domain and the central domain interface and could destabilize the RYR2 channel promoting Ca2+ leak-triggered arrhythmias. Extreme N-terminal RyR2 variants alter calcium handling similar to classical CPVT1 Abnormal Ca2+ kinetics as well as uncontrolled Ca2+ release underlies CPVT1 In vitro arrhythmia studies with iPSCs show nadolol is an effective treatment In silico 3D modeling of RYR2 revealed pathogenicity of N-terminal variants
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Affiliation(s)
- Marissa J Stutzman
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - C S John Kim
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - David J Tester
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA; Department of Cardiovascular Medicine/Division of Heart Rhythm Services; Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN 55905, USA
| | - Samantha K Hamrick
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Steven M Dotzler
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - John R Giudicessi
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA; Department of Cardiovascular Medicine/Division of Heart Rhythm Services; Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN 55905, USA
| | - Marco C Miotto
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Jeevan B Gc
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York 10032, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York 10032, USA
| | - Andrew R Marks
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Michael J Ackerman
- Department of Molecular Pharmacology and Experimental Therapeutics; Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA; Department of Cardiovascular Medicine/Division of Heart Rhythm Services; Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN 55905, USA; Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN 55905, USA.
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Stutzman MJ, Kim CJ, Tester DJ, Hamrick SK, Marcantonio E, MIOTTO M, Marks A, Ackerman MJ. PO-705-07 A NOVEL RYR2 CHANNEL STABILIZER EFFECTIVELY RESCUES CALCIUM HANDLING KINETICS ASSOCIATED WITH CATECHOLAMINERGIC POLYMORPHIC VENTRICULAR TACHYCARDIA IN PATIENT-SPECIFIC INDUCED PLURIPOTENT STEM CELL-DERIVED CARDIOMYOCYTES. Heart Rhythm 2022. [DOI: 10.1016/j.hrthm.2022.03.1078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ye D, Zhou W, Hamrick SK, Tester D, Kim CJ, Barajas-Martinez HM, Hu D, Giudicessi JR, Antzelevitch C, Ackerman MJ. PO-615-05 ACACETIN, A POTENT TRANSIENT OUTWARD CURRENT BLOCKER, MAY BE A NOVEL THERAPEUTIC FOR KCND3-ENCODED KV4.3 GAIN-OF-FUNCTION-ASSOCIATED J-WAVE SYNDROMES. Heart Rhythm 2022. [DOI: 10.1016/j.hrthm.2022.03.793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hamrick SK, Kim CJ, Tester DJ, Giudicessi JR, Ackerman MJ. A Patient-Specific Re-Engineered Cardiomyocyte Model Confirms the Circumstance-Dependent Arrhythmia Risk Associated with the African-Specific Common SCN5A Polymorphism (p.S1103Y): Implications for the Increased Sudden Deaths Observed in Black Individuals During the COVID-19 Pandemic. Heart Rhythm 2021; 19:822-827. [PMID: 34979239 DOI: 10.1016/j.hrthm.2021.12.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/14/2021] [Accepted: 12/24/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND During the early stages of the coronavirus disease 2019 (COVID-19) pandemic, a marked increase in sudden cardiac death (SCD) was observed. The p.S1103Y-SCN5A common variant, present in ∼8% of individuals of African descent, may be a circumstance-dependent, SCD-predisposing, pro-arrhythmic polymorphism in the setting of hypoxia-induced acidosis or QT-prolonging drug use. OBJECTIVE To ascertain the effects of acidosis and hydroxychloroquine (HCQ) on the action potential duration (APD) in a patient-specific induced pluripotent stem cell cardiomyocyte (iPSC-CM) model of p.S1103Y-SCN5A. METHODS iPSC-CMs were generated from a 14-year-old p.S1103Y-SCN5A-positive African American male. The patient's variant-corrected iPSC-CMs (isogenic control, IC) were generated using CRISPR/Cas9 technology. FluoVolt voltage sensing dye was used to assess APD90 values in p.S1103Y-SCN5A-iPSC-CMs compared to IC before and after an acidotic state (pH 6.9) or 24 hours of treatment with 10 μM HCQ. RESULTS Under baseline conditions (pH 7.4), there was no difference in APD90 values of p.S1103Y-SCN5A versus isogenic control iPSC-CMs (p = NS). In the setting of acidosis (pH 6.9), there was a significant increase in fold-change of APD90 in p.S1103Y-SCN5A iPSC-CMS compared to IC iPSC-CMs (p < 0.0001). Similarly, with 24h 10 μM HCQ treatment, the fold-change of APD90 was significantly higher in p.S1103Y-SCN5A iPSC-CMs compared to IC iPSC-CMs (p < 0.0001). CONCLUSIONS Although the African-specific p.S1103Y-SCN5A common variant had no effect on APD90 under baseline conditions, the physiologic stress of either acidosis or HCQ treatment significantly prolonged the APD90 in patient-specific, re-engineered heart cells.
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Affiliation(s)
- Samantha K Hamrick
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Cs John Kim
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - David J Tester
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - John R Giudicessi
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Departments of Cardiovascular Medicine (Clinician-Investigator Training Program), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN.
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Gao X, Kim M, Zhou W, Hamrick SK, John Kim C, Tester D, Ackerman MJ. B-PO01-007 THE EFFICACY OF MEXILETINE TREATMENT IN PATIENT-SPECIFIC RE-ENGINEERED CARDIOMYOCYTE MODELS OF LONG QT SYNDROME TYPE 1, 2, AND 3. Heart Rhythm 2021. [DOI: 10.1016/j.hrthm.2021.06.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Stutzman MJ, Kim CJ, Hamrick SK, Clemens DJ, Dotzler SM, Ye D, Tester D, Ackerman MJ. B-PO04-001 CHARACTERIZATION OF EXTREME N-TERMINAL RYR2 VARIANTS FOUND OUTSIDE CPVT1 VARIANT CLUSTER REGIONS SHOW CA2+ HANDLING ABNORMALITIES CONSISTENT WITH CLASSICAL CPVT. Heart Rhythm 2021. [DOI: 10.1016/j.hrthm.2021.06.698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Tester DJ, Bombei HM, Fitzgerald KK, Giudicessi JR, Pitel BA, Thorland EC, Russell BG, Hamrick SK, Kim CSJ, Haglund-Turnquist CM, Johnsrude CL, Atkins DL, Ochoa Nunez LA, Law I, Temple J, Ackerman MJ. Identification of a Novel Homozygous Multi-Exon Duplication in RYR2 Among Children With Exertion-Related Unexplained Sudden Deaths in the Amish Community. JAMA Cardiol 2021; 5:13-18. [PMID: 31913406 DOI: 10.1001/jamacardio.2019.5400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance The exome molecular autopsy may elucidate a pathogenic substrate for sudden unexplained death. Objective To investigate the underlying cause of multiple sudden deaths in young individuals and sudden cardiac arrests that occurred in 2 large Amish families. Design, Setting, and Participants Two large extended Amish families with multiple sudden deaths in young individuals and sudden cardiac arrests were included in the study. A recessive inheritance pattern was suggested based on an extended family history of sudden deaths in young individuals and sudden cardiac arrests, despite unaffected parents. A family with exercise-associated sudden deaths in young individuals occurring in 4 siblings was referred for postmortem genetic testing using an exome molecular autopsy. Copy number variant (CNV) analysis was performed on exome data using PatternCNV. Chromosomal microarray validated the CNV identified. The nucleotide break points of the CNV were determined by mate-pair sequencing. Samples were collected for this study between November 2004 and June 2019. Main Outcomes and Measures The identification of an underlying genetic cause for sudden deaths in young individuals and sudden cardiac arrests consistent with the recessive inheritance pattern observed in the families. Results A homozygous duplication, involving approximately 26 000 base pairs of intergenic sequence, RYR2's 5'UTR/promoter region, and exons 1 through 4 of RYR2, was identified in all 4 siblings of a family. Multiple distantly related relatives experiencing exertion-related sudden cardiac arrest also had the identical RYR2 homozygous duplication. A second, unrelated family with multiple exertion-related sudden deaths and sudden cardiac arrests in young individuals, with the same homozygous duplication, was identified. Several living, homozygous duplication-positive symptomatic patients from both families had nondiagnostic cardiologic testing, with only occasional ventricular ectopy occurring during exercise stress tests. Conclusions and Relevance In this analysis, we identified a novel, highly penetrant, homozygous multiexon duplication in RYR2 among Amish youths with exertion-related sudden death and sudden cardiac arrest but without an overt phenotype that is distinct from RYR2-mediated catecholaminergic polymorphic ventricular tachycardia. Considering that no cardiac tests reliably identify at-risk individuals and given the high rate of consanguinity in Amish families, identification of unaffected heterozygous carriers may provide potentially lifesaving premarital counseling and reproductive planning.
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Affiliation(s)
- David J Tester
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Hannah M Bombei
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Kristi K Fitzgerald
- Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - John R Giudicessi
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Beth A Pitel
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.,Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Erik C Thorland
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.,Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Barbara G Russell
- Division of Pediatric Cardiology, University of Louisville, Louisville, Kentucky
| | - Samantha K Hamrick
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - C S John Kim
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Carla M Haglund-Turnquist
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | | | - Dianne L Atkins
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Luis A Ochoa Nunez
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Ian Law
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Joel Temple
- Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Michael J Ackerman
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
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O'Hare BJ, John Kim CS, Hamrick SK, Ye D, Tester DJ, Ackerman MJ. Promise and Potential Peril With Lumacaftor for the Trafficking Defective Type 2 Long-QT Syndrome-Causative Variants, p.G604S, p.N633S, and p.R685P, Using Patient-Specific Re-Engineered Cardiomyocytes. Circ Genom Precis Med 2020; 13:466-475. [PMID: 32940533 DOI: 10.1161/circgen.120.002950] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND The KCNH2-encoded Kv11.1 hERG (human ether-a-go-go related gene) potassium channel is a critical regulator of cardiomyocyte action potential duration (APD). The majority of type 2 long-QT syndrome (LQT2) stems from trafficking defective KCNH2 mutations. Recently, Food and Drug Administration-approved cystic fibrosis protein trafficking chaperone, lumacaftor, has been proposed as novel therapy for LQT2. Here, we test the efficacy of lumacaftor treatment in patient-specific induced pluripotent stem cell-cardiomyocytes (iPSC-CMs) derived from 2 patients with known LQT2 trafficking defective mutations and a patient with novel KCNH2 variant, p.R685P. METHODS Patient-specific iPSC-CM models of KCNH2-G604S, KCNH2-N633S, and KCNH2-R685P were generated from 3 unrelated patients diagnosed with severe LQT2 (rate-corrected QT>500 ms). Lumacaftor efficacy was also tested by ANEPPS, FluoVolt, and ArcLight voltage dye-based APD90 measurements. RESULTS All 3 mutations were hERG trafficking defective in iPSC-CMs. While lumacaftor treatment failed to rescue the hERG trafficking defect in TSA201 cells, lumacaftor rescued channel trafficking for all mutations in the iPSC-CM model. All 3 mutations conferred a prolonged APD90 compared with control. While lumacaftor treatment rescued the phenotype of KCNH2-N633S and KCNH2-R685P, lumacaftor paradoxically prolonged the APD90 in KCNH2-G604S iPSC-CMs. Lumacaftor-mediated APD90 rescue was affected by rapidly activating delayed rectifier K+ current blocker consistent with the increase of rapidly activating delayed rectifier K+ current by lumacaftor is the underlying mechanism of the LQT2 rescue. CONCLUSIONS While lumacaftor is an effective hERG channel trafficking chaperone and may be therapeutic for LQT2, we urge caution. Without understanding the functionality of the mutant channel to be rescued, lumacaftor therapy could be harmful.
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Affiliation(s)
- Bailey J O'Hare
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - C S John Kim
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Samantha K Hamrick
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Dan Ye
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - David J Tester
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Department of Molecular Pharmacology and Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (B.J.O., C.S.J.K., S.K.H., D.Y., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic (M.J.A.), Mayo Clinic, Rochester, MN.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine (M.J.A.), Mayo Clinic, Rochester, MN
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Tester DJ, Kim CSJ, Hamrick SK, Ye D, O'Hare BJ, Bombei HM, Fitzgerald KK, Haglund-Turnquist CM, Atkins DL, Nunez LAO, Law I, Temple J, Ackerman MJ. Molecular characterization of the calcium release channel deficiency syndrome. JCI Insight 2020; 5:135952. [PMID: 32663189 PMCID: PMC7455073 DOI: 10.1172/jci.insight.135952] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 12/20/2019] [Accepted: 07/01/2020] [Indexed: 11/26/2022] Open
Abstract
We identified a potentially novel homozygous duplication involving the promoter region and exons 1–4 of the gene encoding type 2 cardiac ryanodine receptor (RYR2) that is responsible for highly penetrant, exertion-related sudden deaths/cardiac arrests in the Amish community without an overt phenotype to suggest RYR2-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT). Homozygous RYR2 duplication (RYR2-DUP) induced pluripotent stem cell cardiomyocytes (iPSC-CMs) were generated from 2 unrelated patients. There was no difference in baseline Ca2+ handling measurements between WT-iPSC-CM and RYR2-DUP-iPSC-CM lines. However, compared with WT-iPSC-CMs, both patient lines demonstrated a dramatic reduction in caffeine-stimulated and isoproterenol-stimulated (ISO-stimulated) Ca2+ transient amplitude, suggesting RyR2 loss of function. There was a greater than 50% reduction in RYR2 transcript/RyR2 protein expression in both patient iPSC-CMs compared with WT. Delayed afterdepolarization was observed in the RYR2-DUP-iPSC-CMs but not in the WT-iPSC-CMs. Compared with WT-iPSC-CMs, there was significantly elevated arrhythmic activity in the RYR2-DUP-iPSC-CMs in response to ISO. Nadolol, propranolol, and flecainide reduced erratic activity by 8.5-fold, 6.8-fold, and 2.4-fold, respectively, from ISO challenge. Unlike the gain-of-function mechanism observed in RYR2-mediated CPVT, the homozygous multiexon duplication precipitated a dramatic reduction in RYR2 transcription and RyR2 protein translation, a loss of function in calcium handling, and a calcium-induced calcium release apparatus that is insensitive to catecholamines and caffeine. Molecular and functional characterization of the calcium release channel deficiency syndrome in patient-specific induced pluripotent stem cell-cardiomyocytes.
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Affiliation(s)
- David J Tester
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - C S John Kim
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Samantha K Hamrick
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Dan Ye
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Bailey J O'Hare
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Hannah M Bombei
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Kristi K Fitzgerald
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Carla M Haglund-Turnquist
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Dianne L Atkins
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Luis A Ochoa Nunez
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Ian Law
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Joel Temple
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Michael J Ackerman
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
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