牛磺酸对慢性高脂高糖-内质网应激介导的胰岛β细胞凋亡干预作用研究

Apoptosis of Islet βcells mediated by high fat and high glucose is the important step in the development of T2DM, and docytoplasmic reticulum stress is the main reason starting the apoptosis. Our previous study have proved that rate-limiting enzyme of taurine synthesis was expressed in the islet βcells, indicating that taurine could be biosynthesized in isletβcells. Taurine administration could decrease the apoptosis rate of islet βcells in diabetic rats induced by STZ, and the expressions of apoptosis activation marker protein decreased, but the mechanisms of which is still unknown. This project aims to elucidate the inhibition effects and mechanisms of taurine on endocytoplasmic reticulum and the apoptosis pathway mediated by endocytoplasmic reticulum, as well as the functional restoration effects of taurine on endocytoplasmic reticulum by in vivo and in vitro experiments. Effects of taurine on apoptosis of islet βcells and cell cycles induced by high fat high glucose diet was investigated by flow cytometry, the volume and morphology of islet cells and endocytoplasmic reticulum were observed by electronic microscope, factors of anti-apoptosis,apoptosis promotion, endocytoplamic reticulum marker, proteins folding and degradation of misfolding proteins releated to the function of endocytoplamic reticulum were detected by Real time PCR and Western-blot. Finally the significant factors were further verified by RNAi. The results would provide theoretical basis for using taurine in the prevention and treatment of diabetes of human and animal.

高脂高糖介导的内质网应激是胰岛β细胞凋亡启动的关键因素。本课题组前期研究证明，牛磺酸合成限速酶在胰岛β细胞表达，表明胰岛β细胞能够生物合成牛磺酸，补充牛磺酸能够减少内质网应激介导的凋亡启动标志物表达，且能降低糖尿病大鼠胰岛β细胞凋亡，提示牛磺酸可抑制内质网应激介导的胰岛β细胞凋亡的发生，但其作用机制尚不明确。本项目拟在前期研究基础上结合体内外试验，采用流式细胞术考察牛磺酸对高脂高糖介导的胰岛β细胞凋亡和细胞周期的影响；透射电镜观测胰岛细胞及内质网体积、形态；定量PCR及Western-blot方法检测凋亡相关因子、内质网应激标志物以及与内质网功能恢复相关因子的基因及蛋白表达，并通过RNAi技术进一步验证在体内外试验中基因及蛋白表达变化均显著的因子，探明牛磺酸对高脂高糖条件下内质网应激、内质网应激介导的凋亡及对内质网功能恢复的作用及机制。为应用其防治人类及动物糖尿病提供理论依据。