title: miR-122 regulates collagen production via targeting hepatic stellate cells and suppressing P4HA1 expression.
abstract: OBJECTIVE
  MicroRNAs (miRNAs) have been shown to be involved in many biological processes by affecting their target gene expression. miR-122 has been extensively studied in hepatocarcinogenesis. However, the role of miR-122 in liver fibrosis remains unknown.
  
  
  METHODS
  The mRNA expression levels of miR-122, prolyl 4-hydroxylase subunit alpha-1 (P4HA1), and CCAAT/enhancer binding protein alpha (C/EBPα) were assessed by real-time PCR. The protein expression levels of P4HA1, C/EBPα and collagen, type I, alpha 1 (COL1A1) were analyzed by Western blot and immunofluorescence. MTT assay was used to assess cell proliferation. Chromatin immunoprecipitation (ChIP) assay was used to examine the binding activity of C/EBPα to miR-122 promoter.
  
  
  RESULTS
  miR-122 expression was significantly reduced in transactivated HSCs and in the livers of mice treated with CCl(4). Overexpression of miR-122 inhibited the proliferation of LX2 cells. We also demonstrated that P4HA1 was a target gene of miR-122. The mRNA expression level of PAHA1 inversely correlated with that of miR-122 in HSCs and in the mouse liver. Overexpression of miR-122 markedly attenuated the expression of P4HA1 via targeting a binding site located at 3'-UTR of P4HA1 mRNA. We further showed that miR-122 overexpression led to decreased collagen maturation and ECM production. Finally, the binding activity of C/EBPα to miR-122 promoter was significantly decreased in activated HSCs.
  
  
  CONCLUSIONS
  Our study suggests that miR-122 may play an important role in negatively regulating collagen production in HSCs and that targeted expression of miR-122 in HSCs may represent a new strategy for the treatment of liver fibrosis.
authors.affiliation: Center for Pharmacogenetics, Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA 15261, United States. jil35@pitt.edu
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.forename: Mohammed
authors.initials: M
authors.lastname: Ghazwani
authors.forename: Yifei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jianqin
authors.initials: J
authors.lastname: Lu
authors.forename: Jilong
authors.initials: J
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Fan
authors.forename: Chandrashekhar R
authors.initials: CR
authors.lastname: Gandhi
authors.forename: Song
authors.initials: S
authors.lastname: Li
mesh_terms: D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000502:physiology; D049109:Cell Proliferation; D003094:Collagen / Q000096:biosynthesis*; D055166:Hepatic Stellate Cells / Q000502:physiology*; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics / Q000502:physiology; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000502:physiology*; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D051557:Hepatocyte Nuclear Factor 4; C531907:MIRN122 microRNA, human; D035683:MicroRNAs; D003094:Collagen; C510863:P4HA1 protein, human; D011393:Procollagen-Proline Dioxygenase