胃转流术治疗2型糖尿病与JNK信号通路的关系

Relationship between gastric bypass for type 2 diabetes mellitus and JNK signaling pathway

目的探讨胃转流手术治疗肥胖合并2型糖尿病的机制及其与c-Jun氨基末端激酶(JNK)信号通路的关系。方法将小鼠胰岛素瘤细胞根据不同的处理方式分为4组:完全培养基组(对照组)、30 mmol/L糖培养基组(高糖组)、高糖+100 nmol/L胰高血糖素样肽-1受体类似物艾塞那肽组(艾塞那肽组)及高糖+100 nmol/L胰高血糖素样肽-1受体类似物艾塞那肽+JNK激动剂组(JNK激动剂组)。各组细胞按培养条件培养至第7天时收集细胞,采用MTT法检测细胞活性,流式细胞仪检测细胞凋亡率,Western blot法检测免疫球蛋白结合蛋白(Bip)、CCAAT增强子结合蛋白同源蛋白(CHOP)、caspase-3及P-SAPK/JNK蛋白的表达水平。结果与对照组比较,高糖组和JNK激动剂组的细胞活性明显下降(P<0.05),细胞凋亡率明显增加(P<0.01),P-SAPK/JNK及caspase-3蛋白表达水平明显增高,但Bip和CHOP蛋白表达水平仅高糖组明显升高(P<0.01);与高糖组比较,艾塞那肽组的细胞活性明显升高(P<0.05),细胞凋亡率明显降低(P<0.01),Bip、CHOP、P-SAPK/JNK及caspase-3蛋白表达水平也明显下降(P<0.01),JNK激动剂组的BIP及CHOP蛋白表达水平也明显降低(P<0.01);与艾塞那肽组比较,JNK激动剂组的细胞活性明显下降(P<0.05),细胞凋亡率明显升高(P<0.01),P-SAPK/JNK及caspase-3蛋白表达水平明显升高(P<0.01)。结论胃转流手术可以通过调节胰高血糖素样肽-1分泌增加来抑制胰岛β细胞内质网应激,进而抑制JNK信号通路,保护胰岛β细胞,抑制细胞凋亡,从而达到治疗2型糖尿病的效果。

Objective To explore mechanism of gastric bypass in treating obesity with type 2 diabetes mellitus （T2DM） and its relationship with c-Jun N-terminal kinase （JNK） signaling pathway. Methods The INS-1 cells were divided into 4 groups according to the different treatment： control group （complete medium）, high glucose group （30 mmol/L glucose medium）, exendin-4 group （high glucose＋100 nmol/L exendin-4）, and JNK agonist group （high glucose＋100 nmol/L exendin-4＋JNK agonist）. When these cells were cultured on day 7, the cell activity was assessed by the MTT staining. The cell apoptosis was determined by the fluorescence microscopy analysis after the Hoechst/PI staining and flow cytometric assay after the Annexin V-FITC/PI staining. The expressions of the human immunoglobulin binding protein （Bip）, CCAAT/enhancer-binding protein homologous protein （CHOP）, P-SAPK/JNK, and caspase-3 protein were detected by the Western blot. Results Compared with the control group, the cell activities were significantly decreased （P〈0.05）, the cell apoptosis rates and the P-SAPK/JNK and caspase-3 protein expression levels were significantly increased （P〈0.01） in the high glucose group and the JNK agonist group, but the Bip and CHOP protein expression levels were significantly increased （P〈0.01） in the high glucose group. Compared with the high glucose group, the cell activity was significantly increased （P〈0.05）, the cell apoptosis rate and the Bip, CHOP, P-SAPK/JNK, and caspase-3 protein expression levels were significantly decreased （P〈0.01） in the exendin-4 group, the Bip and CHOP protein expression levels were significantly decreased （P〈0.01） in the JNK agonist group. Compared with the exendin-4 group, the cell activity was significantly decreased （P〈0.05）, the cell apoptosis rate and the P-SAPK/JNK and caspase-3 protein expression levels were significantly increased （P〈0.01） in the JNK agonist group. Conclusion Gastric bypass can inhibit endoplasmic reticulum stress of pancreatic islet β-cells by regulating secretion of glucagon like peptide-1, thereby inhibiting JNK signaling pathway, protecting pancreatic islet β-cells and inhibiting apoptosis, so as to achieve effect of treating T2DM.