Tcf7l2基因表达上调可抑制高糖诱导的β细胞去分化

Increased Levels of Transcription Factor 7-like 2(Tcf7l2) Suppress β Cell Dedifferentiation Induced by High Glucose

胰岛β细胞去分化是β细胞功能衰竭的主要机制之一。转录因子7类似物2(transcription factor 7-like 2,Tcf7l2)表达水平与β细胞的功能密切相关。但是,转录因子Tcf7l2表达水平与高糖诱导的β细胞去分化的关系目前尚未见报道。本研究通过Tcf7l2的RNA干扰和过表达慢病毒转染MIN6细胞,分别下调和上调Tcf7l2的表达。研究分为空载体对照组与Tcf7l2干扰组和Tcf7l2过表达组。高糖(35 mmol/L)干预48 h,采用qRT-PCR和Western印迹检测祖细胞标志基因和β细胞标志基因的表达变化。结果显示,干扰慢病毒转染MIN6细胞12 h,慢病毒感染效率达95%以上,与对照组比较,Tcf7l2 mRNA的干扰率约为83%,蛋白质水平的干扰率约为49%。过表达慢病毒转染MIN6细胞12 h时,慢病毒转染效率达95%以上。与对照组比较,Tcf7l2 mRNA水平增加16倍,蛋白质水平增加4倍。高糖干预细胞48 h,Tcf7l2干扰组的祖细胞标志基因表达明显高于对照组,β细胞标志基因表达明显低于对照组(P<0.05)。相反,Tcf7l2过表达组的祖细胞标志基因表达明显低于对照组,β细胞标志基因表达明显高于对照组(P<0.05)。上述结果提示,Tcf7l2的表达水平与β细胞去分化密切相关;Tcf7l2表达下调可增加高糖诱导的β细胞去分化,而Tcf7l2过表达可减少高糖诱导的β细胞去分化。

Pancreatic β cell dedifferentiation is one of the critical mechanisms of pancreatic β cell dysfunction. The expression level of transcription factor 7-like 2 （Tcf7l2） is closely related with pancreatic β cell function. However, the relationship between the expression of Tcf7l2 and β cell dedifferentiation induced by high glucose remained unknown. In this study, Tcf7l2 expression in MIN6 cells was modulated by plasmids of Tcf7l2 interference or overexpression via lentivirus infection. The MIN6 cells from groups of scrambled, Tcf7l2 interference, or Tcf7l2 overexpression were exposed to high concentration of glucose （35 mmol/L glucose） for 48 hours. qRTPCR and Western blot were performed to determine the mRNA and protein expression of progenitor likecell markers and βcell marker genes. The results showed that after 12 hours incubation, the infection rate in MIN6 cells of the Tcf7l2 interference group achieved over 95% under fluorescence microscopy, and the interference efficiency at the levels of mRNA or protein was about 83% or 49% respectively when compared with the control group. The infection rate also achieved over 95% evaluated under fluorescence microscopy in MIN6 cells of Tcf7l2 overexpression group. The levels of Tcf7l2 mRNA or protein were increased to 15fold or 26fold respectively in the cells with Tcf7l2 overexpression group. The expression of progenitor markers （such as Naong, Ucn3） increased and expression of β cell markers （such as Pdx1, Mafa） decreased significantly in Tcf7l2 interference group. However, the expression of progenitor markers decreased and expression of β cell markers increased significantly in Tcf7l2 overexpression group. The findings suggest that expression of Tcf7l2 was closely associated with β cell dedifferentiation induced by high glucose.