二甲双胍对大鼠胰岛素瘤细胞内质网应激影响的研究

Effect of metformin on endoplasmic reticulum stress in insulinoma cell of rats ability

目的探讨二甲双胍对大鼠胰岛素瘤(INS-1)细胞内质网应激(ERS)的保护作用及其作用机制。方法体外培养INS-1细胞,分为二甲亚砜对照组(DMSO)、二甲双胍组(MET)、毒胡萝卜素组(TG)和毒胡萝卜素+二甲双胍(TG+MET)组。qRT-PCR检测C/EBP同源蛋白(CHOP)mRNA水平。Western blot检测CHOP的蛋白水平,c-Jun氨基端激酶(JNK)活性测定试剂盒检测JNK的磷酸化水平。放射免疫法测定INS-1细胞的胰岛素分泌水平。结果与DMSO组比较,TG组CHOP mRNA(1. 00±0. 17 vs 2. 67±0. 55,P<0. 01)、蛋白和JNK磷酸化水平升高(1. 00±0. 21 vs2. 29±0. 26,P<0. 01),INS-1细胞的胰岛素分泌降低[(8. 33±1. 67)vs(3. 82±1. 09)μmol/L,P<0. 05]。与TG组比较,TG+MET组CHOP mRNA、蛋白和JNK磷酸化降低[(2. 67±0. 55)vs(1. 63±0. 31),(2. 29±0. 26)vs(1. 53±0. 19),P<0. 05],INS-1细胞的胰岛素分泌升高[(3. 82±1. 09)vs(5. 96±0. 87)μmol/L,P<0. 05]。结论 INS-1细胞中二甲双胍可抑制TG诱导的ERS,改善胰岛素分泌水平,可能通过抑制JNK激活实现。

Objective To detect the protective effect of metformin(Met)on endoplasmic reticulum stress in INS-1 cells and to explore the underlying mechanism.MethodsINS-1 cells were cultured in vitro and divided into DMSO control(DMSO)group,metformin(MET)group,thapsigargin(TG)group and thapsigargin + metformin(TG + MET)group. The mRNA or protein levels of C/EBP homologous protein(CHOP)were detected by qRT-PCR or Western blot. The phosphorylation levels of c-Jun N-terminal kinase(JNK)was detected by kits. The insulin secreted by INS-1 was detected by radioimmunoassay.ResultsTG significantly increased the mRNA(2. 67±0. 55 vs 1. 00±0. 17,P<0. 01)and protein levels of CHOP,promoted the phosphorylation of JNK(2. 29±0. 26 vs 1. 00±0. 21,P<0. 01)and reduced the insulin secretion in INS-1 cells[(3. 82 ± 1. 09)vs(8. 33 ± 1. 67)μmol/L,P<0. 05]. Compared with TG group,metformin reduced the mRNA[(1. 63±0. 31)vs(2. 67±0. 55),P<0. 05]and protein levels of CHOP,inhibited JNK phosphorylation[(1. 53±0. 19)vs(2. 29±0. 26),P<0. 05]and increased the insulin secretion in INS-1 cells[(5. 96±0. 87)vs(3. 82±1. 09)μmol/L,P<0. 05].ConclusionMetformin can inhibit the endoplasmic reticulum stress induced by TG and improve the secretion of insulin in INS-1 cells possibly by inhibiting the activation of JNK.