Upregulation of microRNA-126 in Hepatic Stellate Cells May Affect Pathogenesis of Liver Fibrosis Through the NF-κB Pathway

Hepatic fibrosis, which results from chronic liver disease, currently lacks effective treatment. MicroRNAs, a group of small noncoding RNA molecules, have been observed to play an essential role in liver diseases, including hepatic fibrosis. In this study, we described the regulation of nuclear factor kappa B (NF-B) inhibitor alpha (IB) and its possible signaling pathway by miR-126 in human hepatic stellate cell (HSC) line LX-2. The 3-untranslated region (3-UTR) of IB combined with miR-126 was analyzed by using a dual-luciferase reporter assay. Furthermore, the effects of miR-126 on IB mRNA and protein and NF-B protein expression were assessed by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blot analysis in the human HSC LX-2 cell line transfected with miR-126 mimic or inhibitor. Moreover, to understand the molecular mechanism of miR-126 in promoting liver fibrosis through NF-B signaling pathway, the NF-B downstream signaling factors expression such as transforming growth factor (TGF)-1 and collagen I mRNA were detected by real-time qRT-PCR. We identified that IB is a potential target gene of miR-126, by directly targeting its 3-UTR. Endogenous miR-126 and exogenous miR-126 mimic inhibited IB expression. Moreover, overexpression of miR-126 reduced total and the cytoplasm IB protein expression and increased total and cytoblast NF-B protein expression of LX-2. Conversely, knockdown of miR-126 could inhibit NF-B activation by upregulation of IB protein expression. Further, miR-126 promoted TNF-a-induced TGF-1 and collagen I mRNA expression in LX-2 cells. miR-126 may play an important role in hepatic fibrosis by downregulating the expression of IB partly through the NF-B signaling pathway.