(Pro)renin receptor and renovascular hypertension

(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。最近的研究表明，该受体与空泡H+ATPase(V-ATPase)和Wnt信号通路相互作用。然而，PRR的确切生理和病理功能尚不清楚。PRR的完全缺失是致命的，条件基因敲除或其特定的阻断剂的存在使研究这一受体变得困难。我们的初步研究结果表明，在2肾1夹高血压大鼠模型(2K1C)中，肾脏PRR的表达随低钠摄入和肾动脉阻断而增加，PRR参与调节V-ATPase、WNT3a(涉及典型的2-连环蛋白信号通路)和WNT7a(涉及非典型途径)的表达。根据这些数据，PRR很可能参与了肾脏疾病的发生和发展。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V-ATPase和Wnt信号通路相互作用在高血压肾损伤发生中的病理学意义。为了实现这一目标，我们将利用理论基础和新颖的集成方法，包括定位于肾脏的体外和体内研究，包括最先进的细胞和分子技术、siRNA和shRNA、激光扫描共聚焦显微镜和体内微透析，以更严格地测试所提出的想法。根据我们的初步数据，这一假设的中心假设是血管紧张素AT1(AT1R)和AT2(AT2R)受体通过各自的信号通路调节PRR的表达，并且PRR增强V-ATPase、WNT3a和WNT7a的表达和功能，从而诱导2K1C高血压大鼠的肾脏炎症和纤维化。我们将追求以下特定目标：目的1.验证PRR的表达和活性是通过AT1R-丝裂原活化蛋白激酶、核因子-B(NF：B)和激活蛋白-1(AP-1)信号通路上调的假说。目的2.通过AT2R-一氧化氮(NO)-cGMP-蛋白激酶G(PKG)信号通路和两种受体之间的物理相互作用(二聚化)，验证PRR表达和活性下调的假说。目的3.验证V-ATPase介导PRR致2K1C高血压大鼠肾损伤的假说。目的4.在2K1C高血压大鼠模型中，验证PRR调节Wnt3a和Wnt7a表达及其信号通路导致炎症和纤维化的假说。这些研究有望确定与PRR相关的新的病理生理机制及其对肾脏损伤的贡献，并可能导致开发新的治疗策略来治疗高血压引起的肾脏疾病。

DESCRIPTION (provided by applicant): (Pro)renin receptor (PRR) is a newly discovered component of the renin-angiotensin system. Recent studies suggested interaction of this receptor with vacuolar H+ATPase (V-ATPase) and Wnt signaling pathways. However, the exact physiologicand pathologic functions of PRR are not established yet. Total deletion of PRR is lethal, and unavailability of conditional knockout or its specific blockers made it difficult to study this receptor. Our preliminary data demonstrated that renal PRR expression is increased in response to low sodium intake and renal artery clipping of 2-kidney-1-clip hypertension rat model (2K1C), and that PRR contributes to the regulation of expression of V-ATPase, Wnt3a (involving canonical-2-catenin signaling pathway) and Wnt7a (involving non-canonical pathway). Based on these data, it is likely that PRR is involved in development or progression of renal disease. The long-term goal of our research program 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 V-ATPase and Wnt signaling pathways in development of hypertension-induced renal injury. To achieve this goal, we will utilize a rationale and novel integrated approaches, consisting of in vitro and in vivo studies localized to the kidney including state-of-the-art cellular and molecular techniques, siRNA and shRNA, Laser Scanning Confocal FRET microscopy and in vivo microdialysis to more rigorously test the proposed ideas. Based on our preliminary data, the central hypothesis of this proposal is that angiotensin AT1 (AT1R) and AT2 (AT2R) receptors regulate the expression of PRR via their signaling pathways and that PRR enhances the expression and function of V-ATPase, Wnt3a and Wnt7a to induce renal inflammation and fibrosis in 2K1C hypertension rat model. We will pursue the following specific aims: Aim 1. To test the hypothesis that PRR expression and activity are upregulated via AT1R-mitogen-activated protein kinase, nuclear factor-:B (NF:B), and activator protein-1 (AP-1) signaling pathways. Aim 2. To test the hypothesis that PRR expression and activity are downregulated via AT2R-nitric oxide (NO)-cGMP-protein kinase G (PKG) signaling pathway and through physical interaction (dimerization) between these two receptors. Aim 3. To test the hypothesis that V-ATPase mediates PRR induced renal injury in 2K1C hypertension rat model. Aim 4. To test the hypothesis that in the kidney, PRR regulates Wnt3a and Wnt7a expressions and mediates their signaling pathways leading to inflammation and fibrosis in 2K1C hypertension rat model. These studies are expected to identify novel pathophysiologic mechanisms related to PRR and its contribution to renal injury and could lead to development of new therapeutic strategies in treating hypertension-induced renal disease.