运动防治扩张型心肌病的微小RNA-30d机制

Dilated cardiomyopathy (DCM) is a leading cause of sudden death. Except for heart transplantation, no therapeutic strategy currently used can cure DCM. Exercise induced physiolgical hypertrophy is protective for the heart and our data have also demonstrated that exercise protected DCM though its molecular mechanism is unclear. MicroRNA (miRNA, miR) is among the key regulators of gene expression. Our preliminary data based on microRNA arrays and quantitative reverse transcriptase-polymerase chain reactions have indicated that miR-30d was significantly up-regulated in exercise mice than that in control mice both challenged with doxorubicin. Overexpression of miR-30d protected h9c2, a cardiomyocyte cell line, from doxorubicin-induced apoptosis and necrosis. Based on these findings, we will firstly claify the role of miR-30d in the beneficial effects of exercise in DCM by both in vivo and in vitro loss-of-function (inhibitors and knockout mice) and gain-of-function (agomirs and transgenic mice) experiments. Secondly, we will use gene array, bioinformatic analysis, and the rescue experiments both in vitro and in vivo to identify the downstream targets of miR-30d. Our project will identify a miRNA controls the protective role of exercise in DCM and provide novel therapeutic strategies for the treatment of DCM.

扩张型心肌病（DCM）是导致心脏猝死的重要原因之一。除心脏移植术外，尚缺乏彻底的方法。寻找新的治疗DCM的方法具有重大意义。运动所致的生理性心肌肥大对于心脏具有保护效应，我们的前期工作发现，运动能防治DCM，但是其分子机制尚不清楚。微小RNA是基因表达的调控中心之一，我们采用微小RNA芯片和荧光定量PCR技术发现，相较DCM组，微小RNA-30d在运动+DCM组显著上调，且增加微小RNA-30d对于阿霉素诱导的心肌细胞系凋亡、坏死具有保护效应。本项目拟结合功能获得性实验（微小RNA激动剂和过表达小鼠）和功能缺失性实验（微小RNA抑制剂和敲除小鼠），明确其与运动介导的DCM保护效应的关系。然后借助基因芯片、生物信息学、细胞和动物整体水平的逆转实验等揭示微小RNA-30d介导运动所致DCM保护效应的分子基础。本项目将鉴定出一个运动介导的DCM保护效应的关键微小RNA，为DCM的治疗提供新靶点。

心力衰竭是包括扩张性心肌病在内的心脏疾病的终末阶段，目前还没有有效的治疗措施。因此探索心力衰竭的发生的分子机制十分必要。本项目中，我们主要是明确miR-30d在心力衰竭中的作用和分子机制。我们首先细胞水平明确提高miR-30d的表达能够保护心肌细胞的凋亡，抑制成纤维细胞的激活；然后基于miR-30d过表达和敲除大鼠，基于左前降支结扎术，明确了miR-30d的功能，即过表达miR-30d后可以保护缺血后心肌梗死和纤维化的发生，而抑制miR-30d的表达是可以促进心肌梗死和纤维化的发生。最后，我们鉴定出miR-30d心肌保护的下游靶基因：MAP4K4。总之，我们结果显示，miR-30d可以从多个层面（心肌细胞凋亡和成纤维细胞激活）抑制心力衰竭的发生，为心力衰竭的治疗提供了新的潜在的靶点。