TRPC5在糖尿病性心肌病发生发展中的作用及其机制研究

Diabetic cardiomyopathy (DCM) is one of the most severe cardiovascular complications of diabetes mellitus (DM), which causes high mobility and mortality in patients. However, the regulatory roles of the canonical transient receptor potential 5 (TRPC5) in the the onset and development of DCM are largely unknown. In our preliminary experiments, significantly lower levels of fasting blood glucoses and reactive oxygen species in cardiac tissues were observed in the streptozotocin (STZ)-induced diabetic mice with TRPC5 gene deficient. Meanwhile, quantitative proteomics using isobaric tags for relative and absolute quantification (iTRAQ) revealed that the expressions of the proteins which are related to the enhancive cardiac functions were significantly elevated in the heart tissue from the TRPC5 knock-out (TRPC5-/-) mice. Therefore, we hypothesize that the antagonism of TRPC5 might suppress the process of DCM. Base on the data from our preliminary experiments and the documented studies, the present project is designed to further investigate the regulatory effects of TRPC5 on the blood glucose and process of DCM by establishing the type I and type II DM in mice. In addition, in vitro studies will also be performed to evaluate the functional and structural alterations of the primarily cultured cardiomyocytes, myocardial fibroblasts and myocardial microvascular endothelial cells after their TRPC5 genes are modulated. The involved mechanisms will be systematically investigated with the expectation to find the new therapeutical target to DCM.

糖尿病性心肌病(diabetic cardiomyopathy, DCM)是糖尿病的重要并发症之一，具有高致残率和死亡率。而经典瞬时受体电位通道亚型5(canonical transient receptor potential 5, TRPC5)在DCM的发生发展过程中的作用还未有研究。我们通过前期实验发现：TRPC5基因敲除可显著降低1型糖尿病小鼠血糖水平，同时可减少心脏组织氧自由基的产生，并可能与糖尿病小鼠心脏功能的改善显著相关。因此我们推测：TRPC5的抑制可能会减缓DCM的发生发展过程。本项目基于现有研究成果，拟进一步在小鼠糖尿病模型中观测TRPC5对血糖的调节性作用及在DCM的发生发展过程中的作用，并进行细胞水平实验评估TRPC5对高糖或高胰岛素刺激下心肌细胞、心肌成纤维细胞及心肌微血管内皮细胞功能和结构改变的影响及其机制，以期为探寻DCM防治的新靶点提供理论依据。

糖尿病性心肌病(diabetic cardiomyopathy, DCM)发病机制复杂，涉及高糖所致的心肌细胞毒性反应和微血管病变、心肌细胞线粒体损伤、心肌脂代谢异常、心肌炎症反应与细胞凋亡、肾素血管紧张素系统活化以及交感神经与钙输送异常等多个方面。TRPC5具有多种不同的生理功能，并引起了广泛关注，多种TRPC亚型在糖尿病发展过程中的作用逐渐被科研人员所认识。本课题研究TRPC5基因在糖尿病性心肌病发展发生过程中的作用，分别从正常动物，由 STZ 诱导的 1型糖尿病、STZ和高脂饲料同时诱导的 2 型糖尿病模型小鼠，以及细胞水平三个方面，探讨了TRPC5对血糖的调节性作用及在DCM的发生发展过程中的作用。检测了心肌酶、AGEs、MCP-1、胰岛素和肌糖原等物质水平。通过RT-PCR 实验，在 mRNA 水平检测了糖尿病相关基因的表达；在整体动物水平及细胞水平对TRPC5基因通过干预心肌细胞自噬和凋亡，抑制心肌炎症反应进而参与DCM发生发展过程的作用进行全面研究。通过实验我们发现：TRPC5 基因敲除后，不仅促进了葡萄糖的转运，而且在机体的葡萄糖增多时，迅速将葡萄糖转化为肌糖原贮存起来，维持机体血糖稳定。TRPC5通过参与调节心肌细胞自噬凋亡水平，进而对早期糖尿病心肌病产生影响。同时通过参与心肌细胞炎症的调节，进而对糖尿病心肌病的发生发展产生调控作用。另外，通过生物信息学方法对TRPC5基因进行分析调研，发现TRPC5确实参与免疫学过程，也与炎症相关基因以及通路具有关联性。项目研究结果明确，为探寻DCM防治的新靶点提供了理论依据。