Defining the roles of Orai3 channel in cardiomyocytes and cardiomyopathy.

摘要 扩张型心肌病 (DCM) 是一种严重疾病，通常是特发性的，会导致心室扩大 和进行性收缩功能障碍。虽然通常采用联合药物治疗或使用 心脏移植通常是扩张型心肌病的最终治疗方法。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的异常以及心脏功能障碍上。 能量代谢。我们鉴定了Orai3，一种Ca2+选择性离子通道，也是Ca2+存储操作的成员 通道（SOCC），作为维持产后心脏功能所需的关键主动因素。目标 该提案的目的是研究 Orai3 介导的 Ca2 进入的作用和相关的分子机制 在心肌细胞中。为了实现我们的目标，我们已经产生了几种心肌细胞特异性 Orai3 系 基因敲除（Orai3cKO）小鼠。尽管 Orai3cKO 小鼠具有生育能力且可存活，但它们仍会发展为 DCM 与人类 DCM 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 Orai3 缺陷的心肌细胞表现出肌纤维完整性丧失和相关的超微结构异常 参与氧化代谢和自噬的线粒体蛋白严重失调。我们的 初步数据有力地表明，Orai3 通道是心肌功能的重要调节因子，并且 这些数据提供了将 Orai3 介导的 Ca2 信号转导与肌节细胞完整性和生物能学联系起来的证据 平衡。我们假设 Orai3 介导的 Ca2 进入通过 Ca2 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检验我们的假设 追求以下具体目标： 目标 1：表征 Orai3 丢失后的 DCM 表型 在成人心肌中表达；目标 2：阐明 Orai3 缺失导致心脏病的机制 通过分析诱导型 Orai3cKO 小鼠的功能退化和 DCM；目标 3：检验以下假设： Orai3 介导的 Ca2+ 进入调节线粒体代谢。这项工作将导致分子的发现 Orai3 调节心脏功能的机制；确定 Orai 是 DCM 的新型中介者；和 潜在地确定旨在逆转或延迟代谢和功能的新策略 心力衰竭中出现的紊乱。

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.