Etv1 is an Essential Regulator of Fast Conduction Tissues in the Heart

项目总结 通过心房和心室传导系统(VCS)的快速脉冲传播是正常的关键 心脏的激活和收缩能力。影响这些患者传导速度的遗传性和获得性综合征 组织是心律失常疾病的一个重要负担，也是发病率和 死亡率。不幸的是，由于不良的房室传导，目前尚无改善房室传导的治疗方案。 了解基因调控网络。为了找出快速传导的基本调节因素 基因计划，我们利用了先前观察到的神经调节蛋白-1(NRG1)是VCS的关键介质 规格。利用信号转导和VCS转录图谱，我们发现NRG1 通过Ras-MAPK-RSK/MSK信号通路介导心脏的快速传导 转录因子ETV1。ETV1是E-26(ETS)家族转录的Pea3组成员 调节神经细胞类型的规格和电生理调节的因子。我们现在向大家介绍 显示ETV1在建立和维持快速传导基因程序中的关键作用的数据 心脏。ETV1在心房梳状心肌和室间隔细胞中高表达，在那里它上调 心脏传导关键基因Nkx2-5、SCN5A(NaV1.5)和Gja5(Cx40)的表达。因此，ETV1 KO小鼠表现为心房和室间隔传导减慢，其中一个亚群表现为直束支传导阻滞。 膜片钳实验证明了正常生物物理中钠电流的差异 ETV1 KO小鼠心房、VCS和心室肌细胞之间丢失，提示ETV1调节 超越SCN5A的心脏钠电流的其他调节剂。ETV1 KO小鼠也表现出VCS 发育不全，部分显示右束支缺失(RBB)，与 Nkx2-5单倍体缺陷小鼠和患者。对NKX2-5启动子的分析鉴定了一个高度保守的 使用CRISPR-Cas9在体内删除后的Ets结合簇概括了RBB形成的失败。我们 进行了Phewas分析，发现ETV1序列变体和束支之间存在关联 在人类身上形成块状物。进一步探讨ETV1作为快速传导转录调节因子的作用 对于表型，我们提出了以下具体目标：i)确定ETV1调节 心房肌和浦肯野肌细胞钠电流的独特生物物理特性，II)研究 ETV1在成人心脏传导和心律失常发生中的作用，以及iii)阐明ETV1的分子基础 ETV1序列变异携带者和ETV1 KO小鼠的束支阻断。

PROJECT SUMMARY Rapid impulse propagation through the atria and ventricular conduction system (VCS) is critical for normal cardiac activation and contractility. Heritable and acquired syndromes affecting conduction velocity in these tissues account for a significant burden of arrhythmic disease and are a major cause of morbidity and mortality. Unfortunately, no therapeutic options exist for improving atrial and VCS conduction due to poor understanding of the gene regulatory networks. In order to identify essential regulators of the fast conduction gene program, we made use of a previous observation that Neuregulin-1 (NRG1) is the key mediator of VCS specification. Using a signal transduction and VCS transcriptional profiling screen, we discovered that NRG1 mediates fast conduction in the heart through the Ras-MAPK-RSK/MSK signaling pathway and the transcription factor ETV1. ETV1 is a member of the Pea3 group of E-twenty-six (ets) family transcription factors that regulates specification and electrophysiological modulation of neuronal cell types. We now present data demonstrating a critical role of ETV1 in establishing and maintaining the fast conduction gene program in the heart. ETV1 is highly expressed in the atrial pectinated myocardium and VCS, where it up-regulates the expression of key cardiac conduction genes, Nkx2-5, Scn5a (Nav1.5), and Gja5 (Cx40). Consequently, Etv1 KO mice exhibit conduction slowing in the atria and VCS with a subset displaying frank bundle branch block. Patch clamp experiments demonstrated that the normal biophysical differences in the sodium current between atrial, VCS, and ventricular myocytes were lost in Etv1 KO mice, suggesting that ETV1 regulates additional modifiers of the cardiac sodium current beyond Scn5a. Etv1 KO mice also displayed VCS hypoplasia with a proportion showing absence of the right bundle branch (RBB), mirroring the defects seen in NKX2-5 haploinsufficient mice and patients. Analysis of the NKX2-5 promoter identified a highly conserved ets-binding cluster that upon deletion using CRISPR-Cas9 in vivo recapitulated failure of RBB formation. We performed PheWAS analysis and found an association between an ETV1 sequence variant and bundle branch blocks in humans. To further explore the role of ETV1 as a transcriptional regulator of the fast conduction phenotype, we propose the following specific aims: i) determine the mechanism by which ETV1 regulates the unique biophysical properties of the sodium current in atrial and Purkinje myocytes, ii) study the functional role of ETV1 in cardiac conduction and arrhythmogenesis in the adult heart, and iii) elucidate the molecular basis of bundle branch block in carriers of the ETV1 sequence variant and in Etv1 KO mice.