高糖毒性通过JNK信号通路对胰岛β细胞系INS-1细胞活性和凋亡的影响

Effect of high glucose toxicity on JNK pathway,cell viability and apoptosis in pancreatic β-cell line INS-1

目的:研究高糖毒性通过JNK信号分子对INS-1细胞功能影响的分子机制。方法:在5.6mmol/L(5.6G)、11.2mmol/L(11.2G)、33.3mmol/L(33.3G)葡萄糖浓度下加入或者不加IGF-1培养INS-1细胞,观察细胞的活性和凋亡,并通过添加或不添加JNK抑制剂后,观察JNK信号分子和IRS的丝氨酸磷酸化改变。结果:INS-1细胞活性随暴露高糖环境中的葡萄糖浓度和时间增加而下降,IGF-1有增加细胞活性的作用,但其作用随糖浓度增加而受抑制。流式细胞术检测3组细胞总的凋亡率分别为11.3%、12.7%、28.2%,33.3G组凋亡发生率是5.6G组的2.49倍(P<0.01)。高糖激活JNK和IRS的丝氨酸磷酸化,在33.3G组2种蛋白的磷酸化水平分别是11.2G组的3.33倍(P<0.01)和1.17倍(P<0.01),加入IGF-1以后,进一步抑制它们的丝氨酸磷酸化水平。添加JNK抑制剂SP600125后,可以完全抑制JNK的激活,但仅部分抑制IRS的丝氨酸磷酸化水平,并且使33.3mmol/L葡萄糖培养下细胞活性增加8%(P<0.05),凋亡减少49%(P<0.01)。结论:高糖通过激活JNK信号分子抑制IRS信号系统,从而抑制胰岛β细胞活性,促进凋亡发生。阻断JNK信号分子可以通过抑制IRS的丝氨酸磷酸化而减少细胞凋亡,改善胰岛β细胞功能。

AIM：To investigate the effect of high glucose toxicity on JNK pathway and cell function of INS-1 cells.METHODS： Cultured INS-1 cells with or without IGF-1 exposure,were treated with glucose at 3 concentrations （5.6 mmol/L,11.2 mmol/L and 33.3mmol/L）,respectively. MTT was used to measure the cell viability. Apoptosis was determined by immuno-fluorescence and flow-cytometry analysis. The serine 270 phosphorylation of IRS and phosphorylation of JNK in INS-1 cells were detected in the presence or absence of SP600125 treatment.RESULTS： The cell viability decreased and apoptosis increased with elevated glucose concentrations. The percentage of apoptosis cells was 11.3% in 5.6 G group,12.7% in 11.2 G group and 28.2% in 33.3 G group. There was remarkable increase in apoptosis in 33.3 G group with a 2.49-fold increase to the cells in the basal 5.6 mmol/L glucose. High glucose activated the serine 270 phosphorylation of IRS correlates with JNK phosphorylation in INS-1 cells. Using Western blotting analysis,the levels of JNK phosphorylation were 3.33 fold increased and serine 270 phosphorylation of IRS was 1.17 fold increased in 33.3 G group compared to 11.2 G group （P〈0.01）. IGF-1 treatment inhibited phosphorylation of JNK and IRS. SP600125 treatment completely blocked JNK phosphorylation in 11.2 G group and reduced JNK phosphorylation by 90% in 33.3 G group. In addition,SP600125 treatment partly reduced serine 270 phosphorylation of IRS by 88.3% in 11.2 G group and 80% in 33.3 G group,the viability of INS-1 cells increased and the apoptosis decreased.CONCLUSION： The toxicity of chronic high glucose,which inhibits the cells viability and induces the cell apoptosis,might be related to suppress IRS signal by activating the JNK pathway. Blocking the JNK pathway might relieve the effect of glucose toxicity to the β cell function by improving the IRS signal pathway.