Hepatic MIR20B promotes nonalcoholic fatty liver disease by suppressing PPARA

Abstract

Background: Non-alcoholic fatty liver disease (NAFLD) is associated with hepatic metabolic reprogramming that leads to excessive lipid accumulation and imbalances in lipid metabolism in the liver. Although nuclear receptors (NRs) play a crucial role in hepatic metabolic reprogramming, the underlying mechanisms of NR regulation in NAFLD remain largely unclear. Methods: Using network analysis and RNA-seq to determine the correlation between NRs and microRNA in NAFLD patients, we revealed that miR-20b specifically targets PPARα. miR-20b mimic and anti-miR-20b were administered to hepatocytes as well as high fat diet (HFD)- or methionine-deficient diet (MCD)-fed mice to verify the specific function of miR-20b in NAFLD. We tested the inhibition of the therapeutic effect of a PPARα agonist, fenofibrate, by miR-20b. Results: We revealed that miR-20b specifically targets PPARα through miRNA regulatory network analysis of nuclear receptor genes in NAFLD. The expression of miR-20b was upregulated in free fatty acid (FA)-treated hepatocytes and the livers of both obesity-induced mice and NAFLD patients. Overexpression of miR-20b significantly increased hepatic lipid accumulation and triglyceride levels. Furthermore, miR-20b significantly reduced FA oxidation and mitochondrial biogenesis by targeting PPARα. In miR-20b-introduced mice, the effect of fenofibrate to ameliorate hepatic steatosis was significantly suppressed. Finally, inhibition of miR-20b significantly increased FA oxidation and uptake, resulting in improved insulin sensitivity and a decrease in NAFLD progression. Conclusions: Taken together, our results demonstrate that the novel miR-20b targets PPARα, plays a significant role in hepatic lipid metabolism, and present an opportunity for the development of novel therapeutics for NAFLD. Funding: This research was funded by Korea Mouse Phenotyping Project (2016M3A9D5A01952411), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2020R1F1A1061267, 2018R1A5A1024340), the Future-leading Project Research Fund (1.210034.01) of UNIST and the National Research Foundation of Korea (NRF) grant funded by the Korea government (2020R1I1A1A01074940).