title: miR-26a regulates mouse hepatocyte proliferation via directly targeting the 3' untranslated region of CCND2 and CCNE2.
abstract: BACKGROUND
  The deficiency of liver regeneration needs to be addressed in the fields of liver surgery, split liver transplantation and living donor liver transplantation. Researches of microRNAs would broaden our understandings on the mechanisms 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 indirectly, 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 proliferation 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 contrary, miR-26a over-expression showed the opposite results.
  
  
  CONCLUSIONS
  miR-26a regulated mouse hepatocyte proliferation 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 promising regulator in liver regeneration.
authors.affiliation: Organ Transplant Center, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China. gdtrc@126.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Ju
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Yuan
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Zhu
authors.forename: Dong-Ping
authors.initials: DP
authors.lastname: Wang
authors.forename: Xiao-Shun
authors.initials: XS
authors.lastname: He
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D002453:Cell Cycle; D002460:Cell Line; D049109:Cell Proliferation; D056742:Cyclin D2 / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000378:metabolism*; D008115:Liver Regeneration; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; C486196:Ccnd2 protein, mouse; C503689:Ccne2 protein, mouse; D056742:Cyclin D2; D016213:Cyclins; D035683:MicroRNAs; C543693:Mirn26 microRNA, mouse; D016159:Tumor Suppressor Protein p53