microRNA-1通过诱导自噬参与调控糖尿病心肌病心脏功能的机制研究

Diabetic cardiomyopathy is a serious complication of diabetes mellitus, which can be exacerbated by persistent autophagy. Our preliminary experimental results confirmed the presence of myocardial hypertrophy, systolic/diastolic dysfunction and increased myocardial autophagy in mice with type 2 diabetic cardiomyopathy. Moreover, enhancing autophagy in vitro high glucose environment could further change the morphology and function of myocardial cells, indicating autophagy is associated with myocardial cell function. MicroRNA (miR) is a class of non coding small RNA regulating gene expression at the post-transcriptional level and it can regulate the cell autophagy. Our previous studies showed that the myocardial cells of diabetic mice could increase miR-1, and our early study found miR-1 negatively regulated myocardial cell Cx43 in vitro high glucose environment. Cx43 has a negative role on the formation of autophagosomes, suggesting that miR-1 may be involved in the regulation of cardiac function in diabetic cardiomyopathy by inducing autophagy. Based upon previous studies, this project will further validate whether excessive autophagy could damage cardiac function in type 2 diabetic mice in vivo and will observe the changes of myocardial autophagy and cardiac function by adjusting the miR-1 level in diabetic mice using recombinant adeno-associated virus technology. This project helps to clarify the relationship between miR-1, autophagy, and diabetic cardiomyopathy and provides potential new targets for clinical treatment of diabetic cardiomyopathy.

糖尿病心肌病是糖尿病严重并发症，心肌细胞持续性自噬可导致其进一步进展。我们预实验结果显示2型糖尿病心肌病小鼠合并存在心肌肥厚及舒缩功能障碍，心肌细胞中自噬增加，且体外高糖下进一步诱导自噬增强可改变心肌细胞形态功能，提示自噬与心肌细胞功能相关。微小RNA（miR）是一类细胞内发挥转录后调控的非编码小RNA，可调控细胞自噬。我们前期研究证实糖尿病小鼠心肌细胞可上调miR-1，且在体外高糖环境下miR-1可负性调控心肌细胞Cx43，已知Cx43对自噬小体形成有负性调控作用，提示miR-1可能通过诱导自噬参与调控糖尿病心肌病的心脏功能。本项目拟在前期研究基础上，进一步体内验证过度自噬可损害2型糖尿病小鼠心脏功能，并利用重组腺相关病毒技术上/下调糖尿病小鼠心肌miR-1水平，观测心肌细胞自噬及心功能变化，有助于厘清miR-1、自噬、糖尿病心肌病三者间的关系，为临床治疗糖尿病心肌病提供新的潜在靶点。

糖尿病心肌病是糖尿病严重并发症，即使在未发生明显心肌缺血或高血压时，糖尿病也可增加心力衰竭的发生风险。microRNAs在包括糖尿病在内的多种疾病的发病过程中发挥了重要作用，且被认为是治疗心脏疾病的新型靶点。本课题通过建立糖尿病心肌病模型、病毒转染、分子实验、心功能检测、组织病理以及电镜等实验技术，试图阐明miR-1a-3p是否可通过自噬参与调控糖尿病心肌病的心脏功能。研究证实miR-1a-3p能改善糖尿病心肌病小鼠的心脏功能，表现在改善心脏射血分数和短轴缩短率，减少左心室舒张末期内径和收缩末期内径。同时过表达和干扰mmu-miR-1a-3p自噬水平存在显著差异，mmu-miR-1a-3p可使心肌纤维Z线增宽。项目结论在一定程度上为更有效地靶向治疗糖尿病心肌病提供理论依据和可能性。