Molecular characterization of the calcium release channel deficiency syndrome.
JCI Insight
; 5(15)2020 08 06.
Article
em En
| MEDLINE
| ID: mdl-32663189
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.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
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Taquicardia Ventricular
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Canal de Liberação de Cálcio do Receptor de Rianodina
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Duplicação Gênica
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Miócitos Cardíacos
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Células-Tronco Pluripotentes Induzidas
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Homozigoto
Tipo de estudo:
Etiology_studies
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Observational_studies
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Prognostic_studies
Limite:
Adolescent
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Child
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Child, preschool
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article