» Articles » PMID: 38908063

Loss-of-function W4645R Mutation in the RyR2-caffeine Binding Site: Implications for Synchrony and Arrhythmogenesis

Overview
Journal Cell Calcium
Publisher Elsevier
Date 2024 Jun 22
PMID 38908063
Authors
Affiliations
Soon will be listed here.
Abstract

Aims: Previous studies have identified RyR2 W4645R mutation, located in the caffeine-binding site, to associate with CPVT1 pathology. Caffeine binding to its site is thought to displace the carboxyl-terminal domain to Ca-binding, allowing the tryptophan residue (W4645) to regulate Ca sensitivity of RyR2. To gain insights into regulation of RyR2 Ca-binding and its interaction with caffeine-binding site, we introduced W4645R-RyR2 point mutation via CRISPR/Cas9 gene-editing in human induced pluripotent stem cell-derived cardiomyocytes (hiPSCCMs) and characterized their Ca-signaling phenotype compared to WT hiPSCCMs.

Methods And Results: W4645R-RyR2 cardiomyocytes had: (1) no significant change in I magnitude or voltage-dependence; (2) slightly reduced CICR; (3) altered relaxation kinetics of Ca-transients with no change in isoproterenol sensitivity; (4) complete loss of caffeine-triggered Ca release; (5) larger SR Ca leak resulting in 40 % lower SR Ca content, as determined by myocytes' response to 4-CmC; (6) lower incidence of calcium sparks and asynchronous spontaneous SR Ca releases.

Conclusions: W4645R-RyR2 mutation induces loss of caffeine-triggered SR Ca release and enhances SR Ca leak that underlie asynchronous spontaneous Ca releases, triggering arrhythmia and impairing cardiac function.

References
1.
Landstrom A, Dobrev D, Wehrens X . Calcium Signaling and Cardiac Arrhythmias. Circ Res. 2017; 120(12):1969-1993. PMC: 5607780. DOI: 10.1161/CIRCRESAHA.117.310083. View

2.
Sham J, Cleemann L, Morad M . Functional coupling of Ca2+ channels and ryanodine receptors in cardiac myocytes. Proc Natl Acad Sci U S A. 1995; 92(1):121-5. PMC: 42829. DOI: 10.1073/pnas.92.1.121. View

3.
Zhang X, Haviland S, Wei H, Saric T, Fatima A, Hescheler J . Ca2+ signaling in human induced pluripotent stem cell-derived cardiomyocytes (iPS-CM) from normal and catecholaminergic polymorphic ventricular tachycardia (CPVT)-afflicted subjects. Cell Calcium. 2013; 54(2):57-70. PMC: 3781932. DOI: 10.1016/j.ceca.2013.04.004. View

4.
Cleemann L, Wang W, Morad M . Two-dimensional confocal images of organization, density, and gating of focal Ca2+ release sites in rat cardiac myocytes. Proc Natl Acad Sci U S A. 1998; 95(18):10984-9. PMC: 28007. DOI: 10.1073/pnas.95.18.10984. View

5.
Zhang X, Morad M . Calcium signaling in human stem cell-derived cardiomyocytes: Evidence from normal subjects and CPVT afflicted patients. Cell Calcium. 2016; 59(2-3):98-107. PMC: 4834249. DOI: 10.1016/j.ceca.2015.12.002. View