miR-155 modulates fatty acid accumulation by targeting C/EBPβ in free fatty acid-induced steatosis in HepG2 cells

Background: The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is not well understood, which has led to unsatisfactory therapeutic solutions. In the present study, we investigated the role of miR-155 in free fatty acid (FFA)-exposed HepG2 cells. Furthermore, we determined the target gene of miR-155 involved in intracellular fatty acid accumulation. Methods: HepG2 cells were transfected with miR-155 mimics or inhibitor with or without FFA exposure. miR-155 expression was quantified by quantitative real-time RT-PCR. Intracellular fatty acid accumulation was visualized by Nile red staining, flow cytofluorometric analysis, and fluorescence microscopy. Western blot was used to determine the expression level of the target gene. In addition, functional rescue experiments were performed based on miR-155 inhibitor and siRNAs to the target gene. Results: miR-155 level was significantly elevated in HepG2 cells exposed with FFA. Furthermore, inhibition of miR-155 was observed to promote fatty acid accumulation in the absence of FFA in vitro. In addition, overexpression of miR-155 was capable of blunting fatty acid accumulation in the presence of FFA in vitro. CCAAT/enhancer binding protein β (C/EBPβ) was validated as a target gene of miR-155 involved in fatty acid accumulation. Interfering C/EBPβ in HepG2 cells could reverse the promotion effect of miR-155 inhibitor on lipogenesis. Conclusions: miR-155 controls fatty acid accumulation by targeting C/EBPβ. Intervention of miR-155/C/EBPβ might be a novel therapeutic strategy for NAFLD.