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 AdS-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.
Jian ZhouWei-Qiang JuXiao-Peng YuanXiao-Feng ZhuDong-Ping WangXiao-Shun He
