Neddylation and cardiac protein quality control

描述（由申请人提供）：泛素和泛素样蛋白的翻译后修饰是蛋白质质量控制的必要条件。泛素介导的蛋白水解缺陷是多种心脏疾病的病因，包括心肌病（DRC）和心肌缺血再灌注（I/R）损伤。然而，人们对NEDD8等泛素样蛋白在心肌细胞（CM）生理和病理生理中的重要性知之甚少。本应用程序的初步数据揭示了NEDD8在CM中的新作用，并形成了我们长期目标的基础：了解NEDD8信号如何被调节以调节CM功能并最终调节心脏病。NEDD8与靶蛋白的偶联或解偶联（去醛化或去醛化）是由一系列酶动态调节的。类黄酮化调节多种基本的细胞过程，包括蛋白质水解。我们的初步数据显示，在心脏疾病的动物模型中，以及在患有缺血性或扩张性心肌病的人类衰竭心脏中，有显着增加的类木化蛋白。由于缺乏NEDD8解凝酶的小鼠通过破坏蛋白质水解而发展为严重的心肌病，因此，类化蛋白的积累在功能上具有重要意义。通过多种途径抑制类化修饰可保护CMs免受细胞损伤。这些发现共同表明，过量的类木化蛋白会损害蛋白质水解，对CMs有毒性，预防/正常化类木化蛋白的策略可以促进CM的存活和功能。NUB1L是类化修饰的负调节因子。表达NUB1L可减少类化蛋白，增强蛋白酶体功能，防止应激诱导的CM细胞死亡。因此，当前项目的目标是确定NUB1L在心脏中调节类化修饰和蛋白质降解中的作用。我们将测试我们的中心假设，即NUB1L减少类化蛋白并保护心脏免受蛋白质毒性应激。目的1将使用一种新的转基因小鼠模型，确定NUB1L如何调节类化修饰以及类化修饰减弱对心脏结构和功能的影响。目的2将使用转基因报告基因测试NUB1L表达是否增强心脏蛋白酶体功能，并确定抑制类化修饰是否调节心脏中错误折叠蛋白的去除并改变DRC进展。目的3将确定药物抑制剂和NUB1L表达抑制类化修饰对心肌I/R损伤的影响。降低类化修饰的策略可能是治疗DRC和缺血性心肌病的有效治疗策略。该提案的转化结果包括心肌梗死的肌肉保存和心力衰竭的预防，这是NIH的主要任务。拟议的研究是第一个针对心脏疾病模型中的蛋白质类化修饰，并将采用一种利用转基因小鼠和药物干预的创新方法。

DESCRIPTION (provided by applicant): Posttranslational modification by ubiquitin and ubiquitin-like protein is essential for protein quality control. Defects in ubiquitin-mediated proteolysis are pathogenic to various cardiac diseases including desmin-related cardiomyopathy (DRC) and myocardial ischemia reperfusion (I/R) injury. However, little is known about the importance of ubiquitin-like proteins such as NEDD8 in cardiac myocytes (CM) physiology and pathophysiology. Preliminary data in this application reveal a novel and underappreciated role of NEDD8 in the CM and form the basis of our long-term goal: to understand how NEDD8 signaling can be modulated to regulate CM function and ultimately cardiac disease. Conjugation or deconjugation of NEDD8 to target proteins (neddylation or deneddylation) is dynamically regulated by a family of enzymes. Neddylation regulates a variety of essential cellular processes including proteolysis. Our preliminary data reveal a striking increase of neddylated proteins in the hearts from animal models of cardiac diseases, as well as in human failing hearts with ischemic or dilated cardiomyopathy. The buildup of neddylated proteins is functionally significant, as the mice deficient of a NEDD8 deconjuation enzyme develop severe cardiomyopathy through impairing proteolysis. Attenuation of neddylation by multiple means protects CMs from cell injury. These findings collectively indicate that the excessive neddylated proteins impairs proteolysis and are toxic to CMs, and that strategies to prevent/normalize neddylated proteins promote CM survival and function. NUB1L is a negative regulator of neddylation. NUB1L expression reduces neddylated proteins, enhances proteasomal function, and prevents stress-induced CM cell death. Therefore, the goal of the current project is to define the role of NUB1L in regulation of neddylation and protein degradation in the heart. We will test our central hypothesis that NUB1L reduces neddylated proteins and protects the heart against proteotoxic stress. Aim 1 will determine how NUB1L regulates neddylation and the impact of diminished neddylation on cardiac structure and function, using a novel transgenic mouse model. Aim 2 will test whether NUB1L expression enhances cardiac proteasomal function using a transgenic reporter, and determine whether suppression of neddylation regulates the removal of misfolded proteins in the heart and alters DRC progression. Aim 3 will determine the efficacy of suppression of neddylation, by both pharmacologic inhibitor and NUB1L expression, on myocardial I/R injury. Strategies to reduce neddylation may be effective therapeutic strategies to treat DRC and ischemic cardiomyopathy. The translational outcomes of this proposal include the preservation of muscle in myocardial infarction and prevention of heart failure, key missions of the NIH. The proposed studies are the first to target protein neddylation in models of cardiac diseases and will employ an innovative approach using genetically modified mice and pharmacologic intervention.