MafA磷酸化在胰岛素基因表达中的作用

The role of phosphorylation of MafA in the regulation of insulin gene expression

目的探讨肌腱膜纤维肉瘤癌基因同系物A(MafA)磷酸化在胰岛素基因表达中的作用。方法在不同浓度的葡萄糖或糖原合成酶激酶3(GSK3)抑制剂中培养Ins-1细胞24h后,分别采用Western blotting和RT-PCR法检测MafA蛋白和胰岛素基因的表达。结果高糖组完全磷酸化的MafA和insulin 2mRNA表达均降低(P<0.05)。GSK3抑制剂组完全磷酸化的MafA降低(P<0.05),同时insulin 2mRNA表达降低(P<0.01),分别下降了31.45%和46.77%。结论 MafA在葡萄糖调节胰岛素基因表达中发挥重要作用,葡萄糖毒性可能通过抑制转录因子MafA降低insulin 2基因表达。MafA经GSK3磷酸化后促进insulin 2基因转录。

Objective To study the role of phosphorylated MafA in the regulation of insulin gene transcription in Ins-1 cells.Methods Ins-1 cells were cultured for 24 h media containing different concentrations of glucose or GSK3 inhibitor respectively.The protein leves of MafA and mRNA leves of insulin were detemined by Western blotting or RT-PCR respectively.Results Compared with low glucose group,p-MafA （the complete phosphorylated form of MafA） protein and insulin 2 mRNA levels were decreased significantly in high glucose group （P ＜ 0.05）,while insulin 1 mRNA levels were not.Compared with control,insulin 2 mRNA and p-MafA were decreased significantly in 50 μmol/L or 100 μmol/L GSK3 inhibitor group （P＜0.05）,and the hypophosphorylation MafA was markedly accumulated （P＜0.01）,while insulin 1 mRNA levels were not.Conclusion The data suggest that p-MafA may pay an important role in regulating insulin 2 gene expression.Phosphorylated MafA by GSK3 may activate insulin 2 gene expression.