Hepatic <i>MIR20B</i> promotes nonalcoholic fatty liver disease by suppressing <i>PPARA</i>.

Abstract

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and imbalances in lipid metabolism in the liver. Although nuclear receptors (NRs) play a crucial role in hepatic lipid metabolism, the underlying mechanisms of NR regulation in NAFLD remain largely unclear. Using network analysis and RNA-seq to determine the correlation between NRs and microRNA in human NAFLD patients, we revealed that <i>MIR20B</i> specifically targets <i>PPARA. MIR20B</i> mimic and anti-<i>MIR20B</i> were administered to human HepG2 and Huh-7 cells and mouse primary hepatocytes as well as high-fat diet (HFD)- or methionine-deficient diet (MCD)-fed mice to verify the specific function of <i>MIR20B</i> in NAFLD. We tested the inhibition of the therapeutic effect of a PPARα agonist, fenofibrate, by <i>Mir20b</i> and the synergic effect of combination of fenofibrate with anti-<i>Mir20b</i> in NAFLD mouse model. We revealed that <i>MIR20B</i> specifically targets <i>PPARA</i> through miRNA regulatory network analysis of nuclear receptor genes in NAFLD. The expression of <i>MIR20B</i> was upregulated in free fatty acid (FA)-treated hepatocytes and the livers of both obesity-induced mice and NAFLD patients. Overexpression of <i>MIR20B</i> significantly increased hepatic lipid accumulation and triglyceride levels. Furthermore, <i>MIR20B</i> significantly reduced FA oxidation and mitochondrial biogenesis by targeting <i>PPARA</i>. In <i>Mir20b</i>-introduced mice, the effect of fenofibrate to ameliorate hepatic steatosis was significantly suppressed. Finally, inhibition of <i>Mir20b</i> significantly increased FA oxidation and uptake, resulting in improved insulin sensitivity and a decrease in NAFLD progression. Moreover, combination of fenofibrate and anti-<i>Mir20b</i> exhibited the synergic effect on improvement of NAFLD in MCD-fed mice. Taken together, our results demonstrate that the novel <i>MIR20B</i> targets <i>PPARA</i>, plays a significant role in hepatic lipid metabolism, and present an opportunity for the development of novel therapeutics for NAFLD. 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, NRF-2021R1I1A2041463, 2020R1I1A1A01074940, 2016M3C9A394589324), and the Future-leading Project Research Fund (1.210034.01) of UNIST.