Defining the roles of Orai3 channel in cardiomyocytes and cardiomyopathy.

摘要 扩张型心肌病（DCM）是一种严重的疾病，通常是特发性的，导致心室扩大 和进行性收缩功能障碍虽然通常用药物组合治疗或使用 心脏移植通常是DCM的最终治疗方法。精确的机制 导致心室扩张和功能障碍的原因尚不清楚。然而，在过去的几年里， 人们的注意力集中在收缩性和结构性心肌蛋白质的异常以及心脏功能紊乱上。 能量代谢我们鉴定了Orai 3，它是一种钙选择性离子通道，也是钙库操纵的钙通道的一员。 心血管通道（SOCC）是维持出生后心脏功能所需的关键前摄因素。目标 研究Orai 3介导的Ca 2+内流的作用及其相关的分子机制 在心肌细胞中。为了实现我们的目标，我们已经产生了几个心肌细胞特异性Orai 3细胞系， 敲除（Orai 3cKO）小鼠。虽然组成型Orai 3cKO小鼠是可育的和存活的，但它们仍然发展DCM。 与人类扩张型心肌病的许多解剖学、病理生理学和临床特征非常相似 最终导致心力衰竭（HF）和过早死亡。我们通过初步研究发现， Orai 3缺陷型心肌细胞表现出肌纤维完整性的丧失和相关的超微结构异常。 与氧化代谢和自噬有关的线粒体蛋白严重失调。我们 初步数据强烈表明Orai 3通道是心肌功能的重要调节剂， 这些数据提供了将Orai 3介导的Ca 2+信号传导与肌节细胞完整性和生物能量学联系起来的证据 平衡我们假设Orai 3介导的Ca 2+进入通过Ca 2+激活遗传程序， 促进出生后心肌细胞存活的敏感途径。我们计划通过以下方式来验证我们的假设 追求以下具体目的：目的1：表征Orai 3缺失后的DCM表型 目的2：阐明Orai 3缺失导致心肌缺血的机制， 目的3：为了检验以下假设， Orai 3介导的Ca 2+进入调节线粒体代谢。这项工作将导致发现的分子 Orai 3调节心脏功能的机制;奥赖作为DCM的新介质的鉴定;以及 潜在的识别新的策略，旨在逆转或延迟代谢和功能性 在HF中观察到的紊乱。

Abstract Dilated cardiomyopathy (DCM) is a severe condition, often idiopathic, that results in ventricular enlargement and progressive systolic dysfunction. While usually treated with a combination of medications or using implantable devices, cardiac transplantation is typically the ultimate treatment for DCM. The precise mechanisms leading to ventricular dilatation and dysfunction are not well understood. However, during the last few years, attention has focused on abnormalities of contractile and structural myocardial proteins and disorders of cardiac energy metabolism. We identified Orai3, a Ca2+-selective ion channel and a member of the store-operated Ca2+ channels (SOCC), as a critical proactive factor required for maintenance of postnatal cardiac function. The goal of this proposal is to investigate the roles of Orai3-mediated Ca2+ entry and associated molecular mechanisms in cardiomyocytes. To pursue our goal, we have generated several lines of cardiomyocyte-specific Orai3 knockout (Orai3cKO) mice. While constitutive Orai3cKO mice are fertile and viable, they nevertheless develop DCM that closely resembles many of the anatomical, pathophysiological, and clinical features of human DCM culminating in heart failure (HF) and premature death. We discovered through our preliminary research that Orai3-deficient cardiomyocytes exhibited loss of myofiber integrity and ultrastructural abnormalities associated with severe dysregulation of mitochondrial proteins involved in oxidative metabolism and autophagy. Our preliminary data strongly indicate that the Orai3 channel is an essential regulator of cardiac muscle function, and the data provide evidence linking Orai3-mediated Ca2+ signaling to sarcomere cell integrity and bioenergetics balance. We hypothesize that Orai3-mediated Ca2+ entry activates genetic programs through Ca2+ sensitive pathways that promote survival of post-natal cardiomyocytes. We plan to test our hypothesis by pursuing the following Specific Aims: Aim 1: To characterize the DCM phenotype following loss of Orai3 expression in the adult myocardium; Aim 2: To elucidate mechanisms by which Orai3 loss leads to cardiac function deterioration and DCM by analyzing inducible Orai3cKO mice; and Aim 3: To test the hypothesis that Orai3-mediated Ca2+ entry regulates mitochondrial metabolism. This work will lead to discovery of the molecular mechanisms by which Orai3 regulates heart function; identification of Orai as a novel mediator of DCM; and potential identification of new strategies aimed at reversing or delaying the metabolic and functional derangements seen in HF.