miR-26a regulates mouse hepatocyte prolifera-tion via directly targeting the 3’ untranslated region of CCND2 and CCNE2

BACKGROUND: The deficiency of liver regeneration needs to be addressed in the fields of liver surgery, split liver transplan-tation and living donor liver transplantation. Researches of microRNAs would broaden our understandings on the mecha-nisms of various diseases. Our previous research confirmed that miR-26a regulated liver regeneration in mice; however, the relationship between miR-26a and its target, directly or in-directly, remains unclear. Therefore, the present study further investigated the mechanism of miR-26a in regulating mouse hepatocyte proliferation. METHODS: An established mouse liver cell line, Nctc-1469, was transfected with Ad5-miR-26a-EGFP, Ad5-anti-miR-26a-EGFP or Ad5-EGFP vector. Cell proliferation was assessed by MTS, cell apoptosis and cell cycle by flow cytometry, and gene expression by Western blotting and quantitative real-time PCR. Dual-luciferase reporter assays were used to test targets of miR-26a. RESULTS: Compared with the Ad5-EGFP group, Ad5-anti-miR-26a-EGFP down-regulated miR-26a and increased prolif-eration of hepatocytes, with more cells entering the G1 phase of cell cycle (82.70%±1.45% vs 75.80%±3.92%), and decreased apoptosis (5.50%±0.35% vs 6.73%±0.42%).CCND2 and CCNE2 were the direct targeted genes of miR-26a. miR-26a down-regulation up-regulated CCND2 and CCNE2 expressions and down-regulated p53 expression in Nctc-1469 cells. On the con-trary, miR-26a over-expression showed the opposite results. CONCLUSIONS: miR-26a regulated mouse hepatocyte pro-liferation by directly targeting the 3’ untranslated regions of cyclin D2/cyclin E2; miR-26a also regulated p53-mediated apoptosis. Our data suggested that miR-26a may be a promis-ing regulator in liver regeneration.