TGF-β induces liver fibrosis via miRNA-181a-mediated down regulation of augmenter of liver regeneration in hepatic stellate cells

Objective To study the role of miRNA-181a and augmenter of liver regeneration in TGF-beta-induced fibrosis in hepatic stellate cells. Methods LX2 cells were treated with 20 ng/ml TGF-beta for 24 h. miRNA-181a, ALR plasmid and empty vectors were transfected using siPORT NeoFx reagent. Cells were harvested after 48 h or 72 h of transfection for protein or RNA analysis. Western blotting was performed for ALR, TGF-beta receptor II (TGF beta-RII), collagen 1A1 (COLL1A1), alpha-smooth muscle cell actin (aSMA), rac1, E-cadherin and beta-actin. Quantitative RT-PCR was performed for ALR, GAPDH, miRNA-181a or 5S rRNA. Results TGF-beta induced the expression of miRNA-181a, which in turn down-regulated ALR thereby induced the fibrosis markers, such as COLL1A1, a-SMA and rac1 in hepatic stellate cells. Over-expression of miRNA-181a down-regulated expression of ALR and up-regulated expression of fibrosis markers. On the other hand, ALR over-expression resulted in a decrease in miRNA-181a expression and fibrosis markers. Over-expression of ALR also inhibited the expression of TGF beta-RII and increased expression E-cadherin. Conclusion TGF-beta induced miRNA-181a, which in turn induced fibrosis, at least in part, by inhibiting ALR. ALR inhibited TGF-beta action by decreasing the expression of TGF-RII, thereby inhibiting miRNA-181a expression and fibrosis markers. ALR could serve as a potential molecule to inhibit liver fibrosis.