EHD proteins in cardiac membrane protein targeting and remodeling

描述（由申请人提供）：健康心脏中的膜兴奋性和兴奋-收缩（EC）偶联依赖于完整膜蛋白（离子通道、转运体、受体）的适当表达、运输和保留。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，紧密同步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，尽管它具有明显的重要性，但对于心脏中整体膜蛋白靶向的分子机制的身份知之甚少。这项多PI提案的重点是确定心脏膜蛋白靶向和调控的新途径，目的是确定心脏膜兴奋性调控及其在疾病中的失调的新机制。Eps15同源结构域（EHD）基因产物（EHD1-4）是细胞内蛋白，似乎是膜蛋白运输的关键调节因子，但在任何器官系统中都没有得到很好的研究。我们的研究小组（Boyden & Mohler）最近提供的证据表明，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，我们发现其中一种内体蛋白EHD3在心脏Na/Ca交换器（NCX）的膜运输中起着至关重要的作用。此外，我们发现EHD蛋白在人类心血管疾病的大型动物模型中受到差异调节，这表明EHD蛋白可能在心肌梗死（MI后）后膜蛋白的重塑中发挥关键作用。

DESCRIPTION (provided by applicant): Membrane excitability and excitation-contraction (EC) coupling in the healthy heart rely upon the proper expression, trafficking, and retention of integral membrane proteins (ion channels, transporters, 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, being tightly synchronized to assure the proper responses to stress1. 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 of the molecular mechanisms underlying the targeting of integral membrane proteins in the context of the heart. The focus of this multiple PI proposal, 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 as well as its dysregulation in disease. While not well studied in any organ system, Eps15 homology domain-containing (EHD) gene products (EHD1-4) are intracellular proteins that appear to be key regulators of membrane protein trafficking. Previously uncharacterized in the heart, our group (Boyden & Mohler) recently provided evidence that this protein family likely plays indispensible roles in protein trafficking in cardia muscle. Notably, we uncovered a vital role for one of these endosomal proteins, EHD3, in the membrane trafficking of the Na/Ca exchanger (NCX) in heart5. Moreover, we showed that EHD proteins are differentially regulated in large animal models of human cardiovascular disease, suggesting that EHD proteins may play a critical role in the remodeling of membrane proteins following myocardial infarction (post MI). Our initial findings predict a role for EHD proteins in membrane protein trafficking in the healthy and diseased heart. Our overall hypothesis is that EHD proteins are indispensable components in the proper trafficking of integral membrane proteins involved in cardiac excitability and EC coupling, and are involved in the remodeling of the heart over a wide variety of cardiac pathologies. The goal of this proposal is to directly test the role of EHD3 and EHD3 in cardiac structural and electrical activity using innovative in vivo models of EHD protein deficiency.