Neddylation and cardiac protein quality control

描述（申请人提供）：泛素和泛素样蛋白的翻译后修饰对于蛋白质质量控制至关重要。泛素介导的蛋白水解缺陷是多种心脏疾病的致病因素，包括结蛋白相关性心肌病（DRC）和心肌缺血再灌注（I/R）损伤。然而，关于泛素样蛋白如NEDD 8在心肌细胞（CM）生理和病理生理中的重要性知之甚少。本申请的初步数据揭示了NEDD 8在CM中的一种新的和未被充分认识的作用，并形成了我们长期目标的基础：了解NEDD 8信号转导如何被调节以调节CM功能并最终调节心脏疾病。NEDD 8与靶蛋白的缀合或去缀合（neddylation或deneddylation）由酶家族动态调节。Neddylation调节多种必需的细胞过程，包括蛋白水解。我们的初步数据显示，在心脏病动物模型的心脏中，以及在患有缺血性或扩张型心肌病的人类衰竭心脏中，neddylated蛋白质显著增加。neddylated蛋白质的积累在功能上是重要的，因为缺乏NEDD 8去结合酶的小鼠通过损害蛋白质水解而发展为严重的心肌病。通过多种手段减弱neddylation保护CM免受细胞损伤。这些发现共同表明，过量的neddylated蛋白损害蛋白水解，对CM有毒，并且预防/使neddylated蛋白正常化的策略促进CM存活和功能。NUB 1 L是neddylation的负调节因子。NUB 1 L表达减少neddylated蛋白，增强蛋白酶体功能，并防止应激诱导的CM细胞死亡。因此，本项目的目标是确定NUB 1 L在调节心脏中的neddylation和蛋白质降解中的作用。我们将测试我们的中心假设，即NUB 1 L减少neddylated蛋白，并保护心脏免受蛋白毒性应激。目的1将确定NUB 1 L如何调节neddylation和减少neddylation对心脏结构和功能的影响，使用一种新的转基因小鼠模型。目的2将测试NUB 1 L表达是否使用转基因报告增强心脏蛋白酶体功能，并确定neddylation抑制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将确定通过药理学抑制剂和NUB 1 L表达抑制neddylation对心肌I/R损伤的功效。减少neddylation的策略可能是治疗DRC和缺血性心肌病的有效治疗策略。该提案的转化成果包括心肌梗死中的肌肉保护和心力衰竭的预防，这是NIH的关键任务。拟议的研究是第一个在心脏疾病模型中靶向蛋白质neddylation的研究，并将采用一种使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.