肾素（前体）受体调控缺血性心肌病的机制研究

Although the mechanism of ischemic cardiomyopathy is not entirely clear, cardiomyocyte loss is one of the important reasons. The cause of cell loss included apoptosis and autophagy, which can be regulated and is expected to become the breakthrough point to improve cardiac function after myocardial infarction. The activation of renin angiotensin system (RAS), especially for the elevation of angiotensin II (AngII), is involved in the pathogenic process of heart failure. The (pro)renin receptor [(P)RR] which is a new member of RAS, is a molecule that binds prorenin and renin in tissues, not only leading to their activation, but also acting as a signalling receptor for (pro)renin, independent of the formation of Ang II. Furthermore, (P)RR is also a subunit of Wnt signaling pathway. Our previous studies have shown that in cardiomyocytes (P)RR mediated p38MAPK and PI3K/AKT pathway played a vital role in cells apoptosis and secretion of inflammatory cytokines induced by hypoxia/reoxygenation. In this study, using cardiac specific expression (P)RR transgenic mice, we explore the effect of (P)RR on ischemic cardiomyopathy and its underlying molecular mechanisms from animal and cardiomyocytes level. We want to clarify that (P)RR-mediated signaling pathways regulated myocardial autophagy and apoptosis, and led to the occurrence of heart failure after myocardial infarction. We will offer a new target spot and theoretical basis for clinical prevention and treatment of ischemic cardiomyopathy.

缺血性心肌病的发生机制尚未完全明确，心肌细胞丢失是重要原因之一。造成细胞丢失的原因包括凋亡和自噬，因其具有可调控性，有望成为改善心梗后心脏功能的切入点。肾素血管紧张素系统(RAS)的激活特别是血管紧张素II(AngⅡ)参与心衰的发病过程。肾素（前体）受体[(P)RR]是新近发现的跨膜蛋白，肾素及其前体与(P)RR结合具有激活RAS系统和非AngⅡ依赖的细胞信号通路等多重作用。申请人前期研究已证实(P)RR在心肌细胞中激活p38MAPK及PI3K/AKT通路参与缺氧复氧所致细胞凋亡（相关文章发表在Mol Cell Biochem. 2015）。本研究在此基础上，拟通过心脏特异性过表达(P)RR转基因小鼠，从动物和细胞水平探讨(P)RR对缺血性心肌病的调控作用和分子机制，旨在阐明(P)RR通过介导信号通路调控心肌自噬和凋亡，导致心梗后心衰的发生。为缺血性心肌病的临床防治提供新的靶点和理论基础。

目前研究发现，心肌细胞的凋亡和自噬所致大量细胞丢失与缺血性心肌病、心力衰竭密切相关。肾素血管紧张素(RAS)系统的激活特别是血管紧张素II (AngⅡ)参与心力衰竭的发病过程。RAS系统的新成员肾素（前体）受体pRR是新近发现的跨膜蛋白，肾素及其前体与pRR结合具有激活RAS系统和非AngⅡ依赖的细胞信号通路等多重作用。本研究旨在探讨pRR在缺血再灌注损伤及心力衰竭发病过程中的作用及其分子机制。本研究包括细胞实验及临床试验两部分，细胞实验结果发现：缺氧复氧导致心肌细胞凋亡及自噬增加，伴随细胞pRR基因及蛋白表达增加。应用pRR siRNA干扰片段和过表达载体转染心肌细胞，结果证实过表达pRR使缺氧复氧所致心肌细胞凋亡及自噬增加；抑制pRR使缺氧复氧所致心肌细胞凋亡及自噬降低。接下来本研究进一步验证了pRR介导的缺氧复氧所致心肌细胞凋亡自噬增加的分子机制：抑制pRR使Wnt/ β-catenin信号通路的关键蛋白Dvl-1和β-catenin蛋白表达降低；pRR过表达使Dvl-1和β-catenin蛋白表达增高。故细胞实验结果证实RAS系统新成员pRR通过调控Wnt信号通路介导心肌细胞缺氧复氧所致的细胞凋亡和自噬，从而在缺氧复氧损伤中发挥重要作用。临床研究进一步证实了血浆可溶性pRR在心力衰竭患者诊断中的重要作用。结果显示收缩性心力衰竭（HFrEF）患者，血浆可溶性(P)RR浓度较正常对照组显著增高，通过多元逐步回归分析发现左室重量指数（LVMI）和肾小球滤过率（eGFR）是可溶性(P)RR浓度的独立相关因素。本研究为心肌缺血再灌注损伤及心力衰竭的诊治提供新的思路，pRR可作为潜在的诊断标记物和基因治疗靶点。