Prorenin Receptor Mediates Early Changes in Diabetic Kidney

(申请人提供)：(PRO)肾素受体(PRR)是新发现的肾素-血管紧张素系统的组成部分。PRR的确切生理和病理功能尚不清楚。我们在体外和体内的初步研究表明，高血糖增加了PRR的表达和活性，这一过程主要通过血管紧张素AT1受体(AT1R)的异二聚化来调节。由于AT1R和PRR的相互作用，导致V-ATPase和WNT3a的表达和活性上调，导致肾脏炎症、纤维化和蛋白尿。体内肾间质内注射PRR shRNA或WNT3a shRNA可减少蛋白尿、肾脏炎症和与高血糖相关的形态学改变。根据这些数据，PRR很可能直接参与了高血糖所致肾损伤的发生。我们研究计划的长期目标是阐明在体外和体内有助于调节PRR表达和功能的新机制，并评估这种受体与AT1R、空泡ATPase(V-ATPase)和WNT3a相互作用的病理学意义，并导致高血糖诱导的肾脏疾病的发生。为了实现这一目标，我们将利用理论基础和新颖的综合方法，包括在清醒的正常血糖和高血糖链脲佐菌素诱导的糖尿病大鼠中，利用联合敲除肾脏PRR、V-ATPase或WNT3a和肾脏间质微透析技术的体内研究。这些研究将得到最先进的体外细胞和分子技术的补充，这些技术利用siRNA、shRNA、EMSA、芯片分析和激光扫描共聚焦显微镜来严格检验所提出的假设。根据我们最近的观察和初步数据，这一提议的中心假设是，在存在高血糖的情况下，PRR活性是 通过与AT1R二聚化而增加，导致V-ATPase和WNT3a信号通路的表达和活性增强，从而导致肾脏炎症、纤维化和蛋白尿。我们将追求以下具体目标：目的1：验证高血糖增加PRR表达和活性的假说及其与AT1R的异二聚化，从而导致肾脏炎症、纤维化和蛋白尿。目的：验证高血糖增强的PRR活性通过增加V-ATPase的表达和活性而介导肾损伤的假说。目的：验证高血糖增强的PRR活性通过增加Wnt3a的表达和活性而导致肾损伤的假说。这些研究有望确定与PRR相关的新的病理生理机制，并可能导致开发新的治疗策略来治疗高血糖引起的肾脏疾病。

DESCRIPTION (provided by applicant): (Pro)renin receptor (PRR) is a newly discovered component of the renin-angiotensin system. The exact physiologic and pathologic functions of PRR are not established yet. Our preliminary studies in vitro and in vivo demonstrated that hyperglycemia increases PRR expression and activity, a process that is regulated by angiotensin AT1 receptor (AT1R), mainly via their heterodimerization. As a result of the interaction between AT1R and PRR there is upregulation of V-ATPase and Wnt3a expression and activity leading to renal inflammation fibrosis and albuminuria. In vivo intrarenal interstitia administration of PRR shRNA or Wnt3a shRNA reduced albuminuria, renal inflammation and morphologic changes associated with hyperglycemia. Based on these data, it is likely that PRR directly contributes to development of hyperglycemia-induced renal injury. The long-term goal of our research program is to elucidate the in vitro and in vivo novel mechanisms contributing to the regulation of PRR expression and function and evaluate the pathological significance of this receptor interaction with AT1R, vacuolar-ATPase (V-ATPase) and Wnt3a, and lead to development of hyperglycemia- induced renal disease. To achieve this goal, we will utilize a rationale and novel integrated approaches, consisting of in vivo studies utilizing combined knockdown of renal PRR, V-ATPase or Wnt3a and renal interstitial microdialysis technique in conscious normoglycemic and hyperglycemic streptozotocin- induced diabetes rats. These studies will be complemented by state-of-the-art in vitro cellular and molecular techniques utilizing siRNA, shRNA, EMSA, ChIP assays, and Laser Scanning Confocal FRET microscopy to rigorously test the proposed hypothesis. Based on our recent observations and preliminary data, the central hypothesis of this proposal is that in presence of hyperglycemia, PRR activity is increased by dimerization with AT1R leading to enhanced expression and activity of V-ATPase and Wnt3a signaling pathways to induce renal inflammation, fibrosis and albuminuria. We will pursue the following specific aims: Aim 1: To test the hypothesis that hyperglycemia increases PRR expression and activity and its heterodimerization with AT1R, leading to renal inflammation, fibrosis and albuminuria. Aim 2: To test the hypothesis that hyperglycemia- enhanced PRR activity mediates renal injury by increasing the expression and activity of V-ATPase. Aim 3: To test the hypothesis that hyperglycemia-enhanced PRR activity contributes to renal injury via increased expression and activity of Wnt3a. These studies are expected to identify novel pathophysiologic mechanisms related to PRR and could lead to development of new therapeutic strategies for treating hyperglycemia-induced renal disease.