Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, USA.
Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
Int J Mol Sci. 2023 Oct 18;24(20):15307. doi: 10.3390/ijms242015307.
Type-2 ryanodine receptor (RyR2) is the major Ca release channel of the cardiac sarcoplasmic reticulum (SR) that controls the rhythm and strength of the heartbeat, but its malfunction may generate severe arrhythmia leading to sudden cardiac death or heart failure. S4938F-RyR2 mutation in the carboxyl-terminal was expressed in human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) using CRISPR/Cas9 gene-editing technique. Ca signaling and electrophysiological properties of beating cardiomyocytes carrying the mutation were studied using total internal reflection fluorescence microscopy (TIRF) and patch clamp technique. In mutant cells, L-type Ca currents (I), measured either by depolarizations to zero mV or repolarizations from +100 mV to -50 mV, and their activated Ca transients were significantly smaller, despite their larger caffeine-triggered Ca release signals compared to wild type (WT) cells, suggesting I-induced Ca release (CICR) was compromised. The larger SR Ca content of S4938F-RyR2 cells may underlie the higher frequency of spontaneously occurring Ca sparks and Ca transients and their arrhythmogenic phenotype.
2 型兰尼碱受体 (RyR2) 是心脏肌浆网 (SR) 的主要钙释放通道，它控制着心跳的节律和强度，但它的功能障碍可能会产生严重的心律失常，导致心脏性猝死或心力衰竭。使用 CRISPR/Cas9 基因编辑技术，在人类诱导多能干细胞衍生的心肌细胞 (hiPSC-CMs) 中表达羧基末端的 S4938F-RyR2 突变体。使用全内反射荧光显微镜 (TIRF) 和膜片钳技术研究携带突变的搏动心肌细胞的钙信号和电生理特性。在突变细胞中，通过去极化至 0 mV 或从 +100 mV 复极化至 -50 mV 测量的 L 型钙电流 (I) 及其激活的钙瞬变明显较小，尽管与野生型 (WT) 细胞相比，它们的咖啡因触发的钙释放信号更大，表明 I 诱导的钙释放 (CICR) 受损。S4938F-RyR2 细胞中较大的 SR 钙含量可能是其自发发生钙火花和钙瞬变频率更高以及心律失常表型的基础。
