The miR-31/FIH1 pathway involved in TGFβ-induced liver fibrosis

Abstract

Abstract MicroRNAs (miRNAs) are small, non-coding RNAs that regulate various biological processes, including liver fibrosis. Hepatic stellate cells (HSC) play a central role in the pathogenesis of liver fibrosis. By microarray profiling and real-time PCR, we noted that micorRNA-31 (miR-31) expression was significantly increased during activation of HSC from rat, mouse and human respectively. We found miR-31 was particularly upregulated in HSC but not in Hepatocyte during fibrogenesis. Thus, we hypothesized that miR-31 may mediate liver fibrosis. In our study, we observed that reduction of miR-31 expression significantly inhibited HSC activation while overexpression of its expression obviously promoted HSC activation. Moreover, overexpression of miR-31 promoted HSC migration while inhibition of miR-31 had an opposite effect. The biological function of miR-31 during HSC activation might be through targeting FIH1, a suppressor of hypoxia-inducible factor (HIF-1), as knockdown of FIH1 by short hairpin RNA (shRNA) could mimic the effects of miR-31. In addition, we found that only TGFβ, a pivotal regulator in liver fibrosis, remarkably increased miR-31 expression in HSC. And that the effects of TGFβ upon HSCs can be partially counteracted by inhibition of miR-31. Additionally, ChIP experiments and Luciferase reporter assay demonstrated that Smad3, a major TGF--downstream transcription factor, stimulated the transcription activity of miR-31 by binding directly to the promoter of miR-31. In conclusion, miR-31/FIH1 pathway associates with liver fibrosis, perhaps by participating TGFβ/Smad3 signaling in HSC. A c c e p t e d M a n u s c r i p