VIGILIN Involves in Regulation of Imprinting Gene IGF2 and H19 in Human Hepatocellular Carcinoma Cell

Objective To explore possible relationship among expression of human high density lipoprotein binding protein(VIGILIN),H19 and the insulin-like growth factor 2 (IGF2) mRNA in HepG2 cell cycle and investigate the role of VIGILIN in controlling imprinting genes of H19 and IGF2 mRNA expression. Methods We investigated time course cell cycle distribution of HepG2 cells by FACS,analyzed VIGILIN,H19 and IGF2 mRNA expression at the indicated times using RT-PCR,RNAi and real-time PCR. Results Cell-cycle of HepG2 cells was approximately 20 h. 0 h-9 h and 20 h-28 h,9 h-20 h and 28 h-39 h were S-phase and G2/M-G1-phase,respectively. Firstly,cells were synchronized by serum-starvation for 24 h. As expected,VIGILIN transcription was up-regulated with expression peaks at 20 h and 60 h after serum stimulating by the addition of 10% fetal calf serum. In parallel,H19 mRNA had a high expression level at 6 h and 43 h,and IGF2 mRNA was also increasing with cell-cycle. The expression profiles of human VIGILIN,H19,and IGF2 mRNA were ascending with cell-cycle. In addition,the knock-down of VIGILIN expression by transfecting HepG2 cells with shRNA expression plasmid pSIREN-VIG inhibited the expression of human VIGILIN,which led to the expression of H19 mRNA decrease by 12.08%,and IGF2 mRNA increase by 30.13%. Conclusion The expression of VIGILIN and H19 mRNA was the cell-cycle dependent and had something to do with each other. The results clearly shed light on the roles of VIGILIN in controlling expression of the imprinted H19 and IGF2 genes.