高浓度葡萄糖对胰岛细胞的IRS2表达及细胞凋亡的影响

目的 探讨高浓度葡萄糖条件下胰岛细胞胰岛素受体底物2(IRS2)和Bax基因表达和激活情况以及对诱导胰岛细胞凋亡的影响.方法 将小鼠胰腺进行分离纯化所得的胰岛细胞进行体外培养,按培养液里葡萄糖浓度不同分为G1组(5.6 mmol/L)、G2组(7.8 mmol/L)、G3组(11.1 mmol/L)、G4组(16.7 mmol/L)、G5组(22.2 mmol/L)及G6组(27.6mmol/L).细胞培养至72h后,采用放射免疫法检测各组胰岛细胞胰岛素分泌水平、免疫细胞组织化学法检测IRS2表达、免疫荧光法检测细胞Bax激活和细胞核Hoechst33342染色检测细胞凋亡情况.结果 当葡萄糖浓度在5.6～11.1 mmol/L时,胰岛素分泌水平升高,IRS2表达和Bax激活分别呈进行性增加,但此时细胞凋亡率无明显改变.随着葡萄糖浓度升高至超过16.7mmol/L时,IRS2表达逐渐减少,胰岛素分泌量明显降低,而Bax激活则逐渐增强,胰岛细胞凋亡率呈明显增加趋势.结论 高浓度葡萄糖可以导致胰岛细胞IRS2表达下降,胰岛素分泌量下降;同时Bax激活增强,胰岛细胞凋亡率也明显增加.说明IRS2表达下降与凋亡相关蛋白Bax激活及其胰岛细胞凋亡可能存在必然的联系,而且IRS2表达下降可能是胰岛素分泌减少的原因之一.增强胰岛素信号传导通路中IRS2蛋白的表达可能对于保护胰岛细胞有重要作用.

Abstract：

Objective To investigate the role of insulin receptor substrate 2(IRS2) and Bax on mouse islet cell apoptosis in the presence of high glucose in vitro.Methods The pancreatic islet cells were isolated from Kunming mice and divided into 6 groups(G1-G6 groups)for a 72-h culture in the media containing different concentrations of glucose(5.6,7.8,11.1,16.7,22.2,and 27.6 mmol/L,respectively).Insulin secretion by the cells was evaluated by radioimmunoassay,and the expressions of IRS2 and Bax were detected using immunocytochemistry and immunofluorescence assay,respectively.Hoechst33342 staining was employed to observe the cell apoptosis. Results Exposure to 5.6-11.1 mmol/L glucose resulted in increased insulin secretion and progressive elevation of IRS2 and Bax expression,whereas the cell apoptosis underwent no obvious changes.In the presence of glucose above 16.7 mmol/L,the percentages of apoptotic islet cells increased with glucose concentration,but insulin secretion and IRS2 expression decreased;Bax expression significantly increased in the presence of high-concentration glucose.Conclusion Prolonged exposure of mouse islet cells to high glucose induces apoptosis and impairs insulin secretion of the cells.Decreased IRS2 expression and increased Bax expression may play an important role in the glucotoxicity in mouse islet cells.

High glucose lowers insulin receptor substrate 2 expression and induces apoptosis in mouse islet cells in vitro

Objective To investigate the role of insulin receptor substrate 2(IRS2) and Bax on mouse islet cell apoptosis in the presence of high glucose in vitro.Methods The pancreatic islet cells were isolated from Kunming mice and divided into 6 groups(G1-G6 groups) for a 72-h culture in the media containing different concentrations of glucose(5.6,7.8,11.1,16.7,22.2,and 27.6 mmol/L,respectively).Insulin secretion by the cells was evaluated by radioimmunoassay,and the expressions of IRS2 and Bax were detected using i...