硫氧环蛋白相互作用蛋白与糖尿病关系的研究

Relationship between Thioredoxin Interacting Protein and Diabetes Mellitus

目的研究高糖环境下INS-1细胞中硫氧环蛋白相互作用蛋白(thioredoxin interacting protein,TXNIP)的表达对胰岛素分泌的影响以及N-乙酰半胱氨酸(N-acetylcysteine,NAC)、艾塞那肽(Exenatide,Ex-4)的保护作用。方法以含11.1 mmol/L葡萄糖的RPMI 1640培养液培养INS-1细胞,当细胞生长至80%融合时,分别转入含有4.0 mmol/L葡萄糖(NG组)、16.7 mmol/L葡萄糖(HG组)及16.7 mmol/L葡萄糖+10 mmol/L NAC(HG+N组)、16.7 mmol/L葡萄糖+100 nmol/L Ex-4(HG+E组)的RPMI 1640培养液中继续培养48 h;采用real-time PCR法检测TXNIP、胰岛素基因及胰岛素转录因子MafA的mRNA水平。结果HG组与NG组比较,TXNIP mRNA的表达明显上升,胰岛素mRNA、MafA mRNA的表达均明显下降,差异均有统计学意义(均P<0.01)。HG+N组、HG+E组与HG组比较,TXNIP mRNA的表达均明显下降,胰岛素mRNA、MafA mRNA的表达均明显提高,差异均有统计学意义(均P<0.01)。结论高浓度葡萄糖可通过介导TXNIP的过度表达而导致胰岛素基因及MafA表达下降;特异性地抑制高糖下TXNIP的过度表达可以恢复胰岛素基因及MafA的表达。

Objective To study the expression of thioredoxin interacting protein（TXNIP）under high glucose in INS-1 cells,and its effects on insulin secretion,N-acetylcystein（NAC）,Exenatide（Ex-4）.Methods INS-1 cells were cultured in RPMI 1640 media containing 11.1 mmol/L glucose.When cells were 80% confluent,they were cultured for 48 h in media containing 4.0 mmol/L glucose,16.7 mmol/L glucose,16.7 mmol/L glucose＋10 mmol/L NAC,16.7 mmol/L glucose＋100 nmol/L Ex-4 respectively.The mRNA levels of TXNIP,insulin and MafA were detected by real-time PCR.Results TXNIP levels in INS-1 cells incubated in 16.7 mmol/L glucose for 48 h were significantly increased as compared with those in INS-1 cells incubated in 4.0 mmol/L glucose.mRNA levels of insulin,and MafA were significantly decreased.In INS-1 cells incubated in 16.7 mmol/L glucose＋10mmol/L NAC,16.7 mmol/L glucose＋100 nmol/L Ex-4 for 48 h,the expression of TXNIP was significantly decreased,and the mRNA levels of insulin and MafA were significantly enhanced as compared with those in INS-1 cells incubated in 16.7 mmol/L glucose.There was no significant difference between cells incubated in 4.0 mmol/L glucose,16.7 mmol/L glucose＋10 mmol/L NAC or 16.7 mmol/L glucose＋100 nmol/L Ex-4.Conclusion Elevation in glucose concentrations leads to a decrease in insulin gene and insulin transcript factor MafA mRNA level,and an increase in TXNIP level.But TXNIP,insulin gene and MafA could be revived by NAC,and Ex-4,in elevated glucose in INS-1 cells.We conclude that elevated glucose（glucotoxicity）can reduce the expression of insulin gene,transcript factor MafA through activating TXNIP,and then decrease the expression of insulin and release of insulin.