人VIGILIN参与调控肝癌细胞H19和IGF2印记基因表达的研究

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

目的探讨人高密度脂蛋白结合蛋白基因(VIGILIN)是否参与肝癌细胞在细胞周期中印记基因H19和胰岛素样生长因子2(IGF2)表达的调控。方法通过流式细胞术检测人肝癌细胞HepG2细胞周期选择周期点,采用RT-PCR、RNA干扰、实时荧光定量RT-PCR检测各周期点VIGILIN、H19、IGF2基因表达。结果①HepG2细胞周期约为20h;其中0～9h、20～28h约为S期,9～20h、28～39h约为G2/M、G1期,并选定6h、20h、43h、60h,分别代表S期中期、G1～S期、S期中期和G1期末;②细胞周期同步化后加入血清,刺激VIGILIN转录,上调VIGILIN的表达,从G2/M至G1期,逐渐增加,G1期末达高峰,S期逐渐减少;与之相反,H19的表达,在S期逐渐增加,在G2/MG1期逐渐减少,在S期中期达到高峰。而IGF2的表达也增加但没有明显的周期性。H19与VIGILIN mRNA表达呈负相关(r=-0.6941,P<0.05)。③用VIGILIN shRNA(pSIREN-VIG shRNA)重组载体转染HepG2细胞48h后,相对于3个对照组(未转染组,脂质体转染组和转染pSIREN-GFP shRNA组),实验组VIGILIN mRNA的表达受到明显抑制,此时,IGF2mRNA表达增加30.13%,H19mRNA表达减少12.08%。结论VIGILIN和H19 mRNA表达与细胞周期有关;VIGILIN参与调控H19、IGF2印记基因的表达。

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 cellcycle. 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.