miR-222 targets ACOX1, promotes triglyceride accumulation in hepatocytes

Abstract

Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. However, the exact pathogenesis of NAFLD remains to be elucidated. Despite the association with tumors and cardiovascular diseases, the role of miR-222 in NAFLD remains unclear. The present study was to investigate the role of miR-222 in NAFLD.

Methods: Wild-type C57BL/6 mice were fed a high-fat diet for 12 weeks to induce NAFLD. Normal human liver cell line (L02) was cultured with free fatty acid (FFA)-containing medium to stimulate cell steatosis. The mRNA levels of miR-222 and acyl Coenzyme A xidase 1 (ACOX1) were detected by quantitative-PCR (Q-PCR). The prediction of ACOX1 as the target gene for miR-222 was conducted via TargetScan. The overexpression or inhibition of miR-222 was mediated by miR-222 mimics or antagomir, and intracellular triglyceride levels were measured using a triglyceride kit. Luciferase reporter assays verified ACOX1 as the target gene for miR-222.

Results: miR-222 was significantly elevated in both the in vivo and in vitro NAFLD models. Overexpression of miR-222 significantly increased triglyceride content in the L02 cells, while inhibition of miR-222 expression restricted the accumulation of triglyceride. Overexpression of miR-222 significantly inhibited ACOX1 expression. Transient transfection assays verified that ACOX1 3'-UTR luciferase reporter activity could be inhibited by miR-222 overexpression.

Conclusions: The present study suggested that miR-222 promotes the accumulation of triglycerides by inhibiting ACOX1.

Keywords: ACOX1; Hepatocyte steatosis; NAFLD; miR-222; β-hydroxybutyrate.