The Role of RhoA in the Molecular Pathogenesis of Heart Disease

描述(申请人提供)：特发性扩张型心肌病(IDC)是一种常见疾病(约1：2500)，每年的死亡率超过10000人。这些统计数据强调了开发旨在了解、预防、阻止或逆转进行性心脏功能障碍的新治疗策略的重要性。然而，到目前为止，国际数据中心的病因(S)还不清楚，在数据中心中被异常调控的分子信号机制在很大程度上也是未知的。我们的建议将确定蛋白酪氨酸磷酸酶Shp2对小GTP酶RhoA的异常调节是否直接参与了IDC的发病过程。我们最近发表的工作表明，心肌细胞特异性缺失Shp2的小鼠心脏会发展成严重的扩张型心肌病(DCM)。Shp2是大多数(如果不是全部)受体酪氨酸激酶(RTK)信号通路中的关键正向调节因子。Shp2的缺失还揭示了RhoA信号通路的过度激活，暗示Shp2与心脏中的RhoA信号通路之间存在一种新的、但尚未明确的联系。我们假设，通过Shp2抑制RhoA活性具有心脏保护作用，因此在生化上是预防IDC和心力衰竭所必需的。RhoA是一种小的GTP结合蛋白，参与重要的细胞功能，包括细胞增殖、迁移和细胞骨架重组。最近的翻译工作已经证明了RhoA在心血管疾病中的重要作用，包括高血压和动脉粥样硬化；然而，在这里，潜在的机制也不清楚。在这项提案中，我们将阐明Shp2调控RhoA的机制。这项建议解决了有关RhoA在心肌细胞疾病中的作用的几个有趣和关键的问题。我们计划利用一套综合的生化、细胞生物学、蛋白质组学和遗传学方法，(1)确定RhoA活性在成年心肌中丧失的生理意义；(2)确定RhoA表达和/或活性的丧失是否可以在体内挽救Shp2基因缺失的小鼠的功能性心脏缺陷；(3)利用蛋白质组学和体外和体外生化方法，研究Shp2调控RhoA影响心肌RTK信号转导的机制。这项研究的结果将阐明RhoA活性在成人心肌中的调节机制(S)，揭示Shp2调节RhoA活性可能具有心脏保护作用的方式，并有助于产生治疗IDC患者心力衰竭的新的基于分子的药理靶点。

DESCRIPTION (provided by applicant): Idiopathic dilated cardiomyopathy (IDC), resulting in an enlarged heart that does not pump properly, is a common disease (~ 1:2500) associated with an annual mortality rate of greater than 10000 deaths. These statistics underscore the significance for developing new therapeutic strategies aimed at understanding, preventing, arresting or reversing progressive cardiac dysfunction. However, to date, the cause(s) of IDC is (are) unclear and the molecular signaling mechanisms that are aberrantly regulated in IDC are largely unknown. Our proposal will determine whether aberrant regulation of the small GTPase RhoA by the protein tyrosine phosphatase Shp2 is directly involved in mediating IDC pathogenesis. Our recently published work shows that hearts from mice with cardiomyocyte-specific deletion of Shp2, a key positive regulator in most, if not all, receptor tyrosine kinase (RTK) signaling pathways, develop a severe dilated cardiomyopathy (DCM). This loss of Shp2 also revealed a hyper-activation in the RhoA signaling pathway, implicating a novel, yet undefined, connection between Shp2 and the RhoA signaling pathway in the heart. We hypothesize that suppression of RhoA activity, via Shp2, is cardioprotective and, as such, is biochemically required to prevent IDC and heart failure. RhoA is a small GTP binding protein involved in important cellular functions including cell proliferation, migration and cytoskeletal reorganization. Recent translational work has demonstrated a significant role for RhoA in cardiovascular disease, including hypertension and atherosclerosis; however, here too, the underlying mechanisms are unclear. In this proposal, we will elucidate the mechanisms by which RhoA is regulated by Shp2. This proposal addresses several interesting and key questions with regards to the function of RhoA in cardiomyocyte disease. Using a combined, comprehensive set of biochemical, cell biological, proteomic and genetic approaches, we plan to (1) determine the physiological significance of loss of RhoA activity in the adult myocardium (2) determine whether loss of RhoA expression and/or activity can rescue the functional cardiac defects in Shp2 deleted mice in vivo, and (3) utilize proteomic and in vitro and ex vivo biochemical approaches to examine the mechanism by which Shp2 regulation of RhoA affects RTK signaling in the myocardium. Results of this proposal will elucidate the mechanism(s) by which RhoA activity is regulated in the adult myocardium, reveal the manner in which Shp2 regulation of RhoA activity may be cardioprotective, and assist in the generation of novel, molecular-based pharmacological targets for the treatment of heart failure in patients with IDC.