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目的研究Exendin-4对棕榈酸(PA)诱导的小鼠胰岛βTC6细胞c-jun氨基末端激酶(JNK)信号转导通路活化及凋亡的影响。方法不同浓度PA(0.125、0.25、0.5mmol/L)干预βTC6细胞12、24和48h,cck-8法检测增殖活性;将βTC6细胞分为对照组、PA组、PA+SP 600125组和PA+Exendin-4组,观察细胞形态学变化;TUNEL法测细胞凋亡;Western blot法测p-JNK,JNK、p-c-jun,c-jun蛋白表达。结果 (1)随PA浓度升高及干预时间延长,细胞增殖活性逐渐降低。(2)0.5mmol/LPA干预24h后,βTC6细胞凋亡增加(29.3±2.5)%,JNK,c-jun磷酸化增多。加用SP 600125或Exendin-4后,凋亡减少(22.5±3.2)%和(18.3±2.9)%。PA+Exendin-4组p-JNK与p-c-jun表达有所下降。结论 PA所致的β细胞内JNK及其底物蛋白c-jun磷酸化活化可能是β细胞脂性凋亡的重要环节。Exendin-4可通过抑制β细胞内JNK活化拮抗脂性凋亡。
Objective To investigate the effect of Exendin-4 on activation and apoptosis of c-jun N-terminal kinase (JNK) signal transduction pathway in mouse pancreatic βTC6 cells induced by palmitic acid (PA). Methods The proliferation of βTC6 cells was induced by different concentrations of PA (0.125,0.25,0.5mmol / L) for 12, 24 and 48h, respectively. The βTC6 cells were divided into control group, PA group, PA + SP 600125 group and PA + Exendin-4 group. Cell apoptosis was observed by TUNEL method. The protein expressions of p-JNK, JNK, pc-jun and c-jun were detected by Western blot. Results (1) With the increase of PA concentration and the prolongation of the intervention time, the cell proliferation activity decreased gradually. (2) The apoptosis of βTC6 cells increased by 29.3 ± 2.5% and the phosphorylation of JNK and c-jun increased after treated with 0.5mmol / L LPA for 24h. Apoptosis decreased (22.5 ± 3.2)% and (18.3 ± 2.9)% after addition of SP 600125 or Exendin-4. PA + Exendin-4 group p-JNK and p-c-jun expression decreased. Conclusion PA-induced activation of phosphorylation of JNK and its substrate protein c-jun may be an important part of the β-cell apoptosis. Exendin-4 antagonizes lipoatrophy by inhibiting JNK activation in beta cells.