2型糖尿病大鼠心肌PI3K/Akt/mTOR信号通路的改变及Sirt1的调控机制研究

摘要

Aim To investigate the alteration of Sirt1 and PI3K/Akt/mTOR signaling pathway in type 2 diabetic rats′cardiomyopathy and clarify its role in development of diabetic myocardium.Methods The type 2 diabetes rat model was established by injection of streptozocin after five-week of high fat diet.The rats were randomly divided into model group of 2 weeks, model group of 4 weeks, model group of 8 weeks and control group.The changes of heart function were detected by echocardiography.The alteration of Sirt1, PI3K, Akt, mTOR and S6K1 in myocardium was determined by Western blot.The myocardial cells were randomly divided into following groups:① Control group(normal glucose concentration, 5.5 mmol·L-1);② DMSO group(78.12 mmol·L-1);③ High glucose group(HG,33 mmol·L-1);④ HG+Res(20 μmol·L-1)group;⑤ HG+Nam(40 mmol·L-1) group.The alteration of Sirt1, PI3K, Akt, mTOR and S6K1 in H9C2 cells was determined by Western blot and qRT-PCR.Results WB results showed that Sirt1 was markedly increased in 8 weeks DM rats,compared with 2 weeks DM rats.However,the expressions of PI3K, Akt and mTOR in 2 weeks were significantly increased, without significant change in 4 and 8 weeks.The increased expression of mTOR induced accumulation of S6K1, which was also remarkably increased in 4 weeks after STZ injection, and then it was decreased as DCM developed.WB and qRT-PCR results showed that the expressions of Sirt1, PI3K, Akt, mTOR and S6K1 in HG group were significantly increased compared with control group.Nam treatment significantly lowered Sirt1 expression, resulting in a higher expression of PI3K, Akt, mTOR and S6K1.However,H9C2 cells treated with Res showed a higher expression of Sirt1, resulting in a lower expression of PI3K, Akt, mTOR and S6K1.Conclusion Sirt1 could negatively regulate mTOR signaling in DCM and these changes may be valuable to find a new therapeutic target for diabetic cardiomyopathy.%目的 检测Sirt1及PI3K/Akt/mTOR信号通路相关蛋白在糖尿病大鼠心肌及高糖培养的H9C2细胞中的表达变化,明确其在糖尿病心肌病发生发展中的作用.方法 高脂饮食联合链脲佐菌素建立2 型糖尿病大鼠模型,实验将大鼠分为糖尿病2周、4周、8周模型组和对照组,超声心动图检测大鼠心功能变化,Western blot检测大鼠心肌Sirt1、PI3K、Akt、mTOR、S6K1蛋白表达变化.将H9C2细胞分为正常对照组、DMSO组(78.12 mmol·L-1)、高糖(HG)组(33 mmol·L-1)、白藜芦醇(Res)组(20 μmol·L-1)、尼克酰胺(Nam)组(40 mmol·L-1),Western blot及qRT-PCR研究心肌细胞Sirt1、PI3K、Akt、mTOR、S6K1相关蛋白基因转录及表达,研究Sirt1对该信号通路的调控机制.结果 在动物实验中,与2周DM大鼠比较,8周DM大鼠心肌Sirt1蛋白表达明显增加.2周模型组大鼠相对于正常对照组心肌PI3K、Akt、mTOR、S6K1表达明显增加,且S6K1表达4 周模型组比2周模型组增加更明显,但8周表达降低.在高糖培养的H9C2细胞中,与对照组相比,高糖组Sirt1, PI3K, Akt, mTOR和S6K1表达明显增高.Nam处理组Sirt1表达明显降低,PI3K, Akt, mTOR和S6K1表达增高.Res处理组Sirt1表达明显增高,而PI3K, Akt, mTOR和S6K1表达降低.结论 Sirt1通过负调控PI3K/Akt/mTOR信号通路参与糖尿病心肌损伤,参与早期糖尿病心肌病的发生发展.