血管紧张素-(1-7)通过抑制内质网应激对MIRI的保护作用及机制研究

Apoptosis plays a critical role in myocardial ischemia/reperfusion injury (MIRI). Endoplasmic reticulum stress-induced apoptosis is one of important mechanisms in MIRI. The “PI3K/Akt-SERCA-endoplasmic reticulum stress (ERS)-apoptosis" pathway regulates the MIRI. Whether Ang-(1-7) reduces ERS-induced apoptosis and the I/R injury in MIRI is unclear. Our preliminary experiments showed that Ang-(1-7) can regulate four key points in the "PI3K/Akt-SERCA-ERS- apoptosis" pathway. Therefore, we hypothesized that Ang-(1-7) can activate Akt signaling pathway, improve SERCA activity, maintain intracellular Ca2+, inhibit ERS, and decrease ERS-induced apoptosis, then reduce MIRI. To verify the hypothesis, we will perform the following experiments: i) study Ang-(1-7) protective effects on MIRI in vivo through building wild-type mice myocardial I/R model; ii) study Ang- (1-7) protective effects on H/R injury cardiomyocytes and its mechanism in vivo; iii)) study Ang-(1-7) protective effects on mechanism of MIRI in vivo through building cardiac-specific Akt knockout mice I/R model. We expect to clarify the role of Ang- (1-7) on myocardial I/R injury and its mechanism and provide the theoretical basis for effective prevention of MIRI.

细胞凋亡为心肌缺血再灌注损伤(MIRI)主要病理基础。内质网应激诱导细胞凋亡是MIRI的重要机制。“PI3K/Akt—SERCA—内质网应激—凋亡”通路调控MIRI。Ang-(1-7)能否减少内质网应激诱导的凋亡而减轻MIRI，尚不清楚。预实验结果示，Ang-(1-7)可调节“PI3K/Akt—SERCA—内质网应激—凋亡”通路的四个关键点。因此提出假说：Ang-(1-7)可激活Akt通路，改善SERCA活性，抑制内质网应激，减少内质网应激诱导的细胞凋亡，减轻MIRI。为验证此假说，拟行以下实验：在体研究Ang-(1-7)对野生型小鼠MIRI的保护作用；细胞水平研究Ang-(1-7)对心肌细胞H/R损伤的保护作用及机制；用Akt心肌特异基因敲除小鼠在体研究Ang-(1-7)对MIRI保护作用的机制。希望为MIRI的有效预防提供新途径。

本项目主要研究“Ang-(1-7)通过抑制内质网应激对MIRI的保护作用及机制”。研究内容分两部分：1、在体研究Ang-(1-7)对野生型小鼠MIRI的保护作用。结果显示，Ang-(1-7)可显著减小MIRI小鼠心肌梗死面积、减轻心肌损伤，改善小鼠心脏功能，降低MIRI小鼠心肌细胞凋亡执行蛋白caspase3活性和凋亡相关蛋白（Bcl-2、BIM）表达水平，抑制内质网应激相关蛋白caspase12、p-JNK表达水平，同时改善SERCA活性，对MIRI小鼠起保护作用。Ang-(1-7)的Mas受体抑制剂A-779可抑制Ang-(1-7)的上述保护作用。2、细胞水平研究Ang-(1-7)对H/R心肌细胞的保护作用及机制。结果显示，与H/R组相比，加入Ang-(1-7)可显著降低H/R心肌细胞凋亡（caspase3活性和凋亡相关蛋白表达）和细胞损伤（细胞上清液CK-MB含量），降低H/R心肌细胞内质网应激相关蛋白表达，同时改善SERCA活性，减轻细胞钙超载，对H/R心肌细胞起保护作用。A-779显著抑制Ang-(1-7)的保护作用。另一方面，Akt-siRNA干扰后，Ang-(1-7)对H/R诱导的细胞损伤和细胞凋亡的保护作用明显消失，对内质网应激的抑制作用明显减弱，亦不能改善H/R心肌细胞SERCA活性和细胞钙超载。因此得出结论，Ang-(1-7)可能通过PI3K/Akt通路，改善SERCA活性，减轻细胞钙超载，抑制内质网应激，减轻MIRI心肌细胞凋亡，从而对MIRI起保护作用。本项目研究成果，目前发表SCI论文1篇，IF 3.267分；北大核心期刊论文1篇。本项目培养全日制硕士研究生3名。