title: The Epigenetically-Regulated microRNA-378a Targets TGF-β2 in TGF-β1-Treated Hepatic Stellate Cells.
abstract: OBJECTIVE
  In liver fibrosis, the activation of hepatic stellate cells (HSCs) is considered as a pivotal event. It is well known that transforming growth factor-β1 (TGF-β1) is the main stimuli factor responsible for HSC activation. microRNAs (miRNAs), regulating various biological processes, have recently been shown to be involved in HSC activation. A recent study reported that deficiency of miR-378a contributes to cardiac fibrosis via TGF-β1-dependent paracrine mechanism. However, the involvement of miR-378a and its roles in TGF-β1-induced HSC activation remains largely unknown.
  
  
  METHODS
  miR-378a expression was detected in TGF-β1-treated cells and patients with cirrhosis. Then, effects of miR-378a overexpression on cell proliferation and HSC activation were analyzed. We also analyzed the binding of miR-378a to the 3'-untranslated region of TGF-β2.
  
  
  RESULTS
  In response to TGF-β1, miR-378a expression was down-regulated in a dose-dependent manner. miR-378a overexpression suppressed both cell proliferation and cell cycle in TGF-β1-treated LX-2 cells. Moreover, miR-378a overexpression inhibited TGF-β1-induced HSC activation including the reduction of α-smooth muscle actin (α-SMA) and type I collagen. Similarly, miR-378a resulted in a reduction in cell proliferation, and the expressions of α-SMA and Col1A1 in TGF-β1-treated primary HSCs. Notably, TGF-β2 was confirmed as a target of miR-378a by luciferase reporter assays. Interestingly, miR-378a promoter methylation may be responsible for miR-378a down-regulation in TGF-β1-treated LX-2 cells and TGF-β1-treated primary HSCs. Further studies confirmed that reduced miR-378a was associated with promoter methylation in patients with cirrhosis compared with healthy controls.
  
  
  CONCLUSIONS
  Our results demonstrate that miR-378a expression is associated with its methylation status in TGF-β1-treated cells, and epigenetically-regulated miR-378a inhibits TGF-β1-induced HSC activation, at least in part, via TGF-β2.
authors.affiliation: Department of Infectious Diseases, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Fujun
authors.initials: F
authors.lastname: Yu
authors.forename: Jianhuan
authors.initials: J
authors.lastname: Yang
authors.forename: Kate
authors.initials: K
authors.lastname: Huang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Pan
authors.forename: BiCheng
authors.initials: B
authors.lastname: Chen
authors.forename: Peihong
authors.initials: P
authors.lastname: Dong
authors.forename: Jianjian
authors.initials: J
authors.lastname: Zheng
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D024042:Collagen Type I / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D044127:Epigenesis, Genetic / Q000187:drug effects; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008103:Liver Cirrhosis / Q000235:genetics / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D017207:Rats, Sprague-Dawley; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D053781:Transforming Growth Factor beta2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D024042:Collagen Type I; C526012:MIRN378 microRNA, human; C572773:MIRN378 microRNA, rat; D035683:MicroRNAs; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D004248:DNA (Cytosine-5-)-Methyltransferases; D001374:Azacitidine