Mechanism-inspired Strategies to Prevent Pathogenic Late Na Current in Cardiac Arrhythmias

项目摘要 PI：Manu Ben-Johny，博士 NaV1.5通道基本上参与心脏的正常功能和病理生理学。NAV1.5 功能障碍与各种危及生命的心脏疾病有关，包括先天性和后天性心脏病。 心律失常、心肌病和心力衰竭。这些病理学的一个新的共性增加了 晚期钠电流，导致心脏动作电位平台期持续的钠内流。 了解调节晚期钠电流的机制对于了解神经细胞中的NaV1.5功能障碍至关重要。 心脏病理生理学和开发长期寻求的药理学。我们最近的研究和初步数据 表明晚期钠电流被称为成纤维细胞生长因子钠通道调节剂有力地调节 同源因子（FHF）是心肌细胞内源性因子。然而，FHF如何实现这一重要目标 NaV1.5的调节模式及其与疾病致病机制的相关性尚未完全确定。在这 合作项目，我们寻求（1）剖析FHF调节晚期钠电流的分子机制， (2)以确定该调节方案的生理和病理生理相关性。武装起来， 机械的见解，我们寻求工程师的新的肽为基础的抑制剂晚钠电流。特别是，FHF 经过广泛的选择性剪接，我们评估亚型特异性晚期钠电流调节使用 新的FRET测定和通过广泛的单通道分析。探讨FHF的生理影响 调节晚期钠电流，我们病毒操纵FHF水平在心肌细胞分化的长QT和 混合综合征患者来源的诱导多能干细胞以及转基因小鼠心室肌细胞 肌细胞在这样做的过程中，该提议承诺了新的生物物理学和生理学的见解，以调节 心脏NaV1.5，并告知Na通道病的可变临床表现的潜在机制。

PROJECT SUMMARY PI: Manu Ben-Johny, Ph.D. NaV1.5 channels are fundamentally involved in the normal function and pathophysiology of the heart. NaV1.5 dysfunction is linked to a variety of life-threatening cardiac diseases, including congenital and acquired cardiac arrhythmias, cardiomyopathies, and heart failure. An emerging commonality for these pathologies is increased late Na current, that results in sustained Na influx during the plateau phase of the cardiac action potential. Understanding mechanisms that regulate late Na current is pivotal to understanding NaV1.5 dysfunction in cardiac pathophysiology and for developing long-sought pharmacology. Our recent studies and preliminary data suggest that late Na current is powerfully tuned by a Na channel modulator named fibroblast growth factor homologous factor (FHF) that is endogenous to cardiomyocytes. Yet, how FHF accomplishes this important mode of NaV1.5 regulation and its relevance to disease pathogenic mechanisms is not fully determined. In this collaborative project, we seek (1) to dissect the molecular mechanism of FHF regulation of late Na current, and (2) to identify the physiological and pathophysiological relevance of this modulatory scheme. Armed with in depth mechanistic insights, we seek to engineer novel peptide-based inhibitors of late Na current. In particular, as FHF undergoes extensive alternative-splicing, we evaluate isoform-specificity of late Na current regulation using a novel FRET assay and through extensive single-channel analysis. To probe the physiological impact of FHF regulation of late Na current, we virally manipulate FHF levels in cardiomyocytes differentiated from long-QT and mixed-syndrome patient-derived induced pluripotent stem cells as well as transgenic mouse ventricular myocytes. In so doing, this proposal promises new biophysical and physiological insights into modulation of cardiac NaV1.5 and inform upon mechanisms underlying variable clinical manifestations of Na channelopathies.