神经酰胺通过Rab7a抑制线粒体自噬和脂性自噬参与糖尿病心肌脂毒性的机制研究

糖尿病心肌病（DCM）作为糖尿病的主要心血管并发症之一，是心力衰竭的重要病因，其机制涉及心肌脂毒性。本课题组前期工作发现糖尿病状态下心肌细胞中神经酰胺（Cer）增多、线粒体功能失调、脂滴（LDs）堆积，而抑制Cer合成能改善心肌脂毒性，进一步研究提示Cer可能通过抑制心肌细胞线粒体自噬和脂性自噬造成线粒体失衡、LDs降解减少，其机制涉及调控自噬相关蛋白Rab7a。本项目由此提出假设：糖尿病环境诱导心肌细胞Cer上调及LDs堆积，Cer通过负性调控Rab7a抑制线粒体自噬及脂性自噬、抑制受损线粒体清除和LDs降解，加剧心肌脂毒性。本项目拟复制在体和离体2型糖尿病模型，采用细胞培养、心肌特异性基因敲除或过表达等方法研究以下三个科学问题：1. Cer通过加剧心肌脂毒性参与DCM进程；2. Cer在DCM中对心肌细胞线粒体自噬和脂性自噬的影响；3. Cer通过靶向Rab7a调控自噬通量的机制。

Diabetic cardiomyopathy (DCM), as one of the major cardiovascular complications of diabetes, is a main cause of heart failure. The mechanism of DCM involves myocardial lipotoxicity. Our previous study found that diabetic condition induced myocardial ceramide (Cer) elevation, mitochondrial dysfunction and lipid droplets (LDs) accumulation, and inhibition of Cer synthesis could improve myocardial lipotoxicity. Further research showed that Cer might inhibit mitophagy and lipophagy, which exacerbated mitochondrial dysfunction and LDs accumulation. The mechanism of Cer regulating autophagy may be related with the autophagy-related protein Rab7a. This project proposes the hypothesis that diabetic condition induces Cer upregulation and LDs accumulation in cardiomyocytes. Cer inhibits mitophagy and lipophagy by negatively regulating Rab7a, which further inhibits the clearance of the damaged mitochondrial and the degradation of LDs, and aggravates myocardial lipotoxicity in the end. This project intends to replicate in vivo and ex vivo type 2 diabetes models, using cell culture, myocardial specific gene knockout or overexpression to study the following three scientific issues: 1.the role of Cer in DCM process by exacerbating myocardial lipotoxicity; 2.the effects of Cer on mitophagy and lipophagy of cardiomyocytes in DCM; 3.the mechanisms by which Cer regulating autophagy flux by targeting Rab7a.