Regulation effect of TCF7L2 gene silence on the expression of insulin degrading enzyme in insulin resistant HepG2 cells / 解放军医学杂志

ABSTRACT

Objective To evaluate the effects of transcription factor 7-like 2 (TCF7L2) silence on the expression of insulin degrading enzyme (IDE) in insulin resistance (IR) model HepG2 cells and its possible mechanism. Methods The HepG2 cells were divided into blank group, TCF7L2 interference group, empty vector group, IR group, IR+TCF7L2 interference group, IR+empty vector group. IR-HepG2 cell model was induced by in vitro cultivation o the cells in high concentration of insulin (5 X 10-6 mol/L) for 24 hours; GOD-POD and 2-NBDG method was used to verify successful reproduction of IR-cell model. TCF7L2 specific siRNA lentivirus vector (LV-TCF7L2-siRNA) was constructed with TCF7L2 mRNA coding sequence as the interference target, and it was used to transfect the cells in blank group and IR group. Empty vector virus was used to transfect the cells in empty vector group and IR+empty vector group. The expressions of TCF7L2 and IDE mRNA were detected by qRT-PCR, and the changes in the expression of TCF7L2, IDE, insulin stimulated protein kinase B(AKT) and phosphorylated protein kinase B(p-AKT) were detected by Western blotting. The uptake rate of 2-deoxy-D-glucose (2-NBDG) was analyzed by flow cytometry. Results Compared with that in control group, the glucose consumption and the uptake rate of 2-NBDG significantly decreased in IR group (P<0.01), proving that the IR cell model had been reproduced successfully. Western bloting and qRT-PCR revealed that the expression levels of TCF7L2 and IDE mRNA and protein were obviously decreased in IR group compared with that in blank group (P<0.05), in TCF7L2 interference group than in blank group and empty vector group, and in IR+TCF7L2 interference group than in blank group and IR+empty vector group (P<0.05). Afer physiological insulin stimulation, the expression levels of p-AKT protein decreased more signifcantly in IR group and IR+TCF7L2 interference group than in blank group (P<0.01), while no statistically signifcant difference in the total AKT protein level was found among all the groups. 2-NBDG uptake rate was significantly decreased in TCF7L2 interference group as compared with that in blank group and empty vector group, and also in IR+TCF7L2 interference group than in IR group and IR+empty vector group, respectively P<0.01. ConclusionTe mechanism of IR induced by the interaction of TCF7L2 and IDE might be related to the decreased expression of the insulin signaling pathway key enzyme p-AKT protein.