Wnt Signaling in Cardiac Conduction and Arrhythmogenesis

项目摘要 Wnt信号通路调节心脏形态发生，并与先天性心脏病相关 在老鼠和人类中都有这种疾病。鉴于先天性心脏病通常与脑室 心律失常，这是该患者群体中发病率和死亡率的常见原因，更好地了解 分子基础可能最终会改进诊断和治疗方案。我们发现很多基因 编码离子通道亚基是Wnt在发育过程中的转录靶标，包括主要的钠 通道和缝隙连接亚型在心脏中表达。Wnt信号的丢失导致心脏的改变 使小鼠易患起源于右室的室性心动过速的传导，即使在 没有结构性心脏缺陷。有趣的是，全球转录变化在 Wnt功能丧失小鼠的左、右心室，与明显的电生理改变相平行。 这项提案将试图阐明导致左右差异的基因组调控元件。 Wnt扰动背景下的心室转录变化。我们假设非编码基因组 指导心室特异表达模式的元件可能是遗传性心律失常的基础，如Brugada 主要影响右室的综合征和致心律失常性心肌病。具体来说，第一个 目的阐明Wnt信号调节Hey2在小鼠体内表达的潜在机制 右心室，而Notch信号调节左心室Hey2的表达 接近了。鉴于全基因组关联研究已将HEY2附近的非编码变异与 Brugada综合征，对Wnt和Notch反应的调节元件的扰动可能与 人类疾病。WNT信号在成人获得性心脏病中也是失调的，如心力衰竭， 发病和死亡的主要原因，其中对其在调节传导和 心律失常易感性。在目标2中，我们将确定核β-连锁素是否有变化 蓄积，典型的Wnt信号的效应器，以及它是否与脑内神经传导的变化相关 临床相关的小鼠心力衰竭模型。作为迈向翻译的一步，我们将测量WNT活动和 衰竭和非衰竭心脏的人左心室组织中核β-连环蛋白的积聚 确定含有和不含有β-连环蛋白的细胞核是否表达不同的转录本。最后，目标3将决定 几种临床相关的GSK3抑制剂是否在体外抑制钠通道转录并调节 体内传导速度。

Project Summary The Wnt signaling pathway regulates cardiac morphogenesis and has been associated with congenital heart disease in both mice and humans. Given that congenital heart diseases are often associated with ventricular arrhythmias, a common cause of morbidity and mortality in this patient population, a better understanding of the molecular basis may ultimately improve diagnostic and therapeutic options. We found that many genes encoding ion channel subunits are Wnt transcriptional targets during development, including the major sodium channel and gap junction isoforms expressed in the heart. Loss of Wnt signaling leads to changes in cardiac conduction that predispose mice to ventricular tachycardia originating from the right ventricle, even in the absence of a structural heart defect. Interestingly, global transcriptional changes are highly distinct between the left and right ventricles in Wnt loss of function mice, paralleling the distinct electrophysiologic changes. This proposal will seek to elucidate genomic regulatory elements responsible for differential right versus left ventricular transcriptional changes in the setting of Wnt perturbation. We hypothesize that non-coding genomic elements directing ventricular-specific expression patterns may underlie inherited arrhythmias such as Brugada syndrome and arrhythmogenic cardiomyopathy which primarily affect the right ventricle. Specifically, the first aim will elucidate the underlying mechanism whereby Wnt signaling regulates Hey2 expression in the murine right ventricle, and Notch signaling regulates Hey2 expression in the left ventricle, using transgenic approaches. Given that genome wide association studies have linked non-coding variants near HEY2 with Brugada syndrome, perturbation of regulatory elements responsive to Wnt and Notch may have relevance to human disease. Wnt signaling is also dysregulated in adult acquired heart diseases such as heart failure, a major cause of morbidity and mortality, where much less is known about its role in regulating conduction and arrhythmia susceptibility. In Aim 2, we will determine whether there are changes in nuclear β-catenin accumulation, the effector of canonical Wnt signaling, and whether it correlates with conduction changes in a clinically relevant murine heart failure model. As a step towards translation, we will measure Wnt activity and nuclear β-catenin accumulation in human left ventricular tissue from failing and non-failing hearts, and determine whether nuclei with and without β-catenin express distinct transcripts. Finally, Aim 3 will determine whether several clinically relevant GSK3 inhibitors inhibit sodium channel transcription in vitro and modulate conduction velocity in vivo.