Myocyte specific regulation of metabolism and the response to biomechanical force

描述(申请人提供)：心脏病仍然是我们社会最常见的死亡原因。虽然治疗方法在过去几十年中有了相当大的演变，但这种演变与越来越多的慢性心力衰竭患者的产生是平行的。我们对肾素-血管紧张素-醛固酮系统以外的疾病的病理生理学有更广泛的了解，这对于开发其他治疗心力衰竭的工具是必要的。美国政府的角色 由于错误折叠的蛋白质在心力衰竭发病机制中的明显作用，泛素蛋白酶体系统(UPS)和自噬在维持心脏中关键的蛋白质质量控制功能方面受到越来越多的关注。然而，我们对UPS和自噬系统如何由泛素连接酶指导的理解存在很大差距，泛素连接酶是赋予这两个系统特异性的蛋白质。该项目的长期目标是阐明肌环指(MURF)泛素连接酶在心力衰竭时调节PPARα、PPARB/δ和PPARγ1活性、线粒体动力学和自噬的机制。根据我们的初步研究，我们的中心假设是，Murf泛素连接酶调节PPARα、PPAR？/δ和PPARγ1的活性，控制线粒体ROS，并参与自噬，以背景保护心力衰竭的心肌细胞。一个推论是，抑制MuRF1可能特异性地保护Calpa1诱导的心力衰竭，从而在体内提供更特异的心脏保护性抗Calpa1靶点。我们的假说预测，抑制特定的MURF活性在心力衰竭中可能是有害的，因为PPAR信号在其发病机制(糖尿病心肌病)中是核心的，或者在钙蛋白1介导心力衰竭(缺血再灌注损伤)时是有帮助的。核心假设将通过完成以下特定目标(SA)来验证：(1)阐明Murf家族泛素连接酶在糖尿病心肌病和心力衰竭中的独特作用。(2)确定依赖MuRF1的Calpain 1活性调节心肌线粒体功能和ROS的分子机制。(3)明确心脏MuRF1在体内调节自噬增强心脏对缺血再灌注损伤和心力衰竭的抵抗力的机制。对于SA1，我们将描述MuRF2和MuRF3在高脂饮食诱导的糖尿病心肌病中具有保护作用的机制。对于SA2，我们将确定MuRF1依赖的Calpa1在调节ROS、线粒体动力学和eEF2在心力衰竭中的作用。SA3研究MuRF1调节自噬的机制，以整合抑制MuRF1在心力衰竭中可能具有上下文保护作用的其他方式。目前的研究提供了创新的范例，阐明了Murf蛋白在心力衰竭时保护心脏的作用机制。

DESCRIPTION (provided by applicant): Heart disease remains the most common cause of death in our society. While therapies have evolved considerably over the past decades, this evolution has paralleled the creation of a growing number of patients with chronic heart failure. Our broader understanding of the pathophysiology of disease beyond the renin- angiotensin-aldosterone system is necessary to develop additional tools to treat heart failure. The role of the ubiquitin proteasome system (UPS) and autophagy in maintaining critical protein quality control functions in the heart has gained increasing attention due to the apparent role of misfolded proteins in the pathogenesis of heart failure. However, there is a broad gap in our understanding of how the UPS and autophagy systems are directed by ubiquitin ligases, the proteins that give specificity to both systems. The broad long-term goal of this project is to delineate the mechanisms that Muscle Ring Finger (MuRF) ubiquitin ligases regulate PPARα, PPARß/δ, and PPARγ1 activities, mitochondrial dynamics, and autophagy in the context of heart failure. Based on our preliminary studies, our central hypothesis is that the MuRF ubiquitin ligases are regulate PPARα, PPARß/δ, and PPARγ1 activities, control mitochondrial ROS, and are involved in autophagy to contextually protect cardiomyocytes in heart failure. A corollary hypothesis is that inhibiting MuRF1 may specifically protect against Calpain1-induced heart failure to provide a more specific cardioprotective anti-Calpain1 target in vivo. Our hypothesis predicts that inhibiting specific MuRF activities may be detrimental in heart failure where PPAR signaling is central to its pathogenesis (diabetic cardiomyopathy) or helpful where Calpain1 is mediates heart failure (ischemia reperfusion injury). The central hypothesis will be tested by completing the following Specific Aims (SA): (1) Elucidate the unique roles of MuRF family ubiquitin ligases in diabetic cardiomyopathy and heart failure. (2) Determine the molecular mechanisms MuRF1-dependent Calpain1 activity regulates cardiac mitochondrial function and ROS. (3) Determine the mechanisms cardiac MuRF1 regulates autophagy in vivo to enhance the heart's resistance to ischemia reperfusion injury and heart failure. For SA1, we will characterize the mechanisms MuRF2 and MuRF3 are protective in a high fat diet induced diabetic cardiomyopathy. For SA2, we'll determine the role of MuRF1-dependent Calpain1 in regulating ROS, mitochondrial dynamics, and eEF2 in heart failure. SA3 investigates the mechanisms MuRF1 regulates autophagy to integrate additional ways in which inhibiting MuRF1 may be contextually protective in heart failure. The present studies offer innovative paradigms elucidating the mechanisms in which MuRF proteins may be targeted for their ability to protect the heart in the context of heart failure.