Role of EHD proteins in cardiac excitability and disease

描述（由申请人提供）：心脏的收缩依赖于心肌细胞中完整膜蛋白的适当表达、运输和保留。这些蛋白质从离子通道和转运体到激素受体各不相同。所有这些都在控制心脏收缩和对生理和病理生理刺激的短期和长期适应中发挥关键作用。表达蛋白的谱是动态的，它被调节以确保对压力的适当反应。十年来，将膜蛋白运输功能障碍与心脏病联系起来的研究突出了这一点。然而，尽管其明显的重要性，在天然心脏的背景下，细胞内分子途径支持运输和靶向整体膜蛋白的身份（或功能）知之甚少。本研究计划的重点是确定心脏膜蛋白靶向和调节的新途径，目的是确定心脏膜兴奋性调节的新机制。Eps 15同源结构域（EHD）基因产物（EHD1-4）是细胞内蛋白，似乎是内体运输、脂质稳态、膜蛋白回收和运输的关键调节因子。以前在心脏中未被发现，最近的证据表明，该蛋白质家族可能在心肌蛋白质运输中起着不可或缺的作用。值得注意的是，我们的研究小组最近发现了其中一种蛋白质EHD3在心脏Na/Ca交换器（NCX）的膜运输中的重要作用。本提案的目标是使用最前沿的EHD蛋白缺乏体内模型直接测试这些蛋白在心脏结构和电活动中的作用。调查将在健康和衰竭的心脏中进行。本研究计划的目的是：1)确定EHD蛋白在脊椎动物心脏功能基线和长时间心脏应激中的体内作用；2)确定EHD蛋白在维持心肌细胞兴奋性中的作用；3)确定EHD蛋白在细胞内蛋白质运输中的作用。这里完成的工作将是第一个描述心脏内蛋白质运输和电重塑的功能分子机制。

DESCRIPTION (provided by applicant): Contraction of the heart relies upon the proper expression, trafficking, and retention of integral membrane proteins in cardiac muscle cells. These proteins vary from ion channels and transporters to hormone receptors. All play key roles in governing cardiac contraction and short and long term adaptations to physiological and pathophysiological stimuli. The profile of expressed proteins is dynamic, and it is regulated to assure the proper response to stress. This is highlighted by a decade of research linking dysfunction in membrane protein trafficking with heart disease. Yet, despite its obvious importance, little is known regarding even the identity (or the function) of the intracellular molecular pathways underpinning the trafficking and targeting of integral membrane proteins in the context of the native heart. The focus of this research program is to identify new pathways for membrane protein targeting and regulation in heart with the goal of defining novel mechanisms for the regulation of cardiac membrane excitability. Eps 15 homology domain-containing (EHD) gene products (EHD1-4) are intracellular proteins that appear to be key regulators of endosomal trafficking, lipid homeostasis, membrane protein recycling and trafficking. Previously uncharacterized in the heart, recent evidence demonstrated that this protein family likely plays indispensible roles in protein trafficking in cardiac muscle. Notably, n essential role for one of these proteins, EHD3, in the membrane trafficking of the Na/Ca exchanger (NCX) in heart was recently uncovered by our group. The goal of this proposal is to directly test the role of these proteins in cardiac structural and electrical activity using cuttin-edge in vivo models of EHD protein deficiency. Investigations will be conducted in both healthy and failing hearts. The aims of this research program are to 1) Define the in vivo roles of EHD proteins for vertebrate cardiac function at baseline and during prolonged cardiac stress, 2) identify the role of EHD proteins in the maintenance of myocyte excitability, and 3) define the role of EHD proteins in intracellular protein trafficking. The work completed here will be the firs to characterize the functional molecular mechanisms underpinning both protein trafficking and electrical remodeling within the heart.