miR-1靶向LXRα调控糖尿病心肌中脂质代谢的作用及其机制研究

Diabetic cardiomyopathy (DCM) is a specific cardiomyopathy independent of hypertension, coronary disease and atherosclerosis. It is one of the main causes of death in diabetic patients. Myocardial dysfunction caused by disturbance in the lipid and glucose metabolism is an initial factor resulting in diabetic cardiomyopathy, but the pathogenesis needs further research. Our previous research has found that the expression of LXRα, which closely associated with body energy metabolism, has a abnormal change in the cardiac muscular of DCM rat. Also, our studies have shown that LXR agonists may attenuate the cellular damage of myocardial induced by high glucose in vitro. We have a sufficient reason to speculate that LXRα plays an important role in the occur and develop progress in DCM. MiR-1 can regulate the expression of LXRα by the targeting effect, and it may take part in regulation of the development of DCM. This project intends to use methods such as gene silencing, miRNA transfection, Western blot to investigate the effects and mechanism of miR-1 on the lipid metabolism and disease development in diabetic cardiomyopathy by targeting LXRα in vitro and in vivo. This study is designed to provide further experimental bases for the research of the pathogenesis of DCM and a new therapeutic targets is expected to offered.

糖尿病心肌病是独立于高血压、冠心病以及动脉粥样硬化的特异性心肌病变，是糖尿病患者死亡的主要原因之一。糖脂代谢紊乱导致的心肌功能改变是糖尿病心肌病的始动因素，但其病理机制仍需进一步研究。申请人首次在糖尿病心肌病大鼠模型中发现与多种体内能量代谢密切联系的LXRα及相关基因在心肌组织中的异常表达，体外实验中也发现LXR激动剂可能拮抗高糖所致的心肌细胞损伤，预示LXRα在糖尿病心肌病发生发展过程中的重要作用。miR-1能够靶向调控LXRα的表达，且其可能参与了对糖尿病心肌病发展的调控。本项目拟采用基因沉默、miRNA转染、Western blot等技术，从体内及体外两个方面探讨miR-1靶向调控LXRα在心肌脂质代谢以及糖尿病心肌病发展中的作用及其机制，旨在为糖尿病心肌病发病机制的研究提供更多的实验依据，尽可能为糖尿病心肌病的预防及治疗提供新的靶点。

糖尿病心肌病（Diabetic Cardiomyopathy，DCM）是糖尿病患者的主要心脏并发症之一， 发病率高，危害性大，与糖尿病病人心血管疾病的高发生率和高病死率密切相关。DCM 主要的病理表现有心肌肥大、局灶性心肌坏死、细胞外基质沉积以及心肌纤维化等，可导致心力衰竭、心律失常、心绞痛、心源性休克和猝死等，给糖尿病患者及其家庭造成极大的困扰，DCM的发病机制较为复杂，目前仍未十分明确。因此本研究通过建立大鼠心肌细胞H9C2高糖损伤模型研究LXRα在糖尿病心肌病中发挥的作用以及miR-1参与的分子调控机制对高糖诱导的心肌细胞凋亡和氧化应激水平的影响。本实验应用双荧光素酶实验验证miR-1与LXRα的靶向关系，采用脂质体方法向H9C2细胞分别转染miR-1过表达和干扰载体，用LXRα激动剂GW3965处理H9C2细胞，采用高糖诱导H9C2细胞损伤，通过细胞凋亡、LXRα表达情况、活性氧产生情况以及线粒体膜电位变化水平检测观察LXRα激动剂GW3965对高糖诱导的大鼠心肌细胞凋亡及氧化应激水平的作用，探讨miR-1靶向调控LXRα对高糖诱导的大鼠心肌细胞凋亡及氧化应激的影响。结果表明LXRα激动剂GW3965可激活LXRα蛋白表达，抑制高糖诱导的细胞凋亡，改善高糖诱导的活性氧的增加及细胞线粒体膜电位变化；过表达miR-1可下调LXRα蛋白表达，同时可逆转GW3965对高糖诱导的细胞凋亡的抑制作用，而沉默miR-1可上调LXRα蛋白表达同时可抑制高糖诱导的细胞凋亡，提示miR-1通过靶向LXRα调控高糖诱导的大鼠心肌细胞凋亡及线粒体氧化应激。本研究旨在为糖尿病心肌病发病机制的探明提供更多的实验依据，同时为糖尿病心肌病的预防及治疗提供新的靶点。