Upregulated microRNA-199a-5p inhibits nuclear receptor corepressor 1 translation in mice with non-alcoholic steatohepatitis.

Mounting evidence indicates that dysregulated microRNAs (miRNAs) are important in the etiology and pathogenesis of steatohepatitis. However, the functions of miRNAs in the pathophysiological process of non-alcoholic steatohepatitis (NASH) are poorly understood. In this study, C57BL/6J mice were fed a methionine-choline-deficient (MCD) diet for eight weeks in order to induce hepatic steatohepatitis. Using reverse transcription polymerase chain reaction, the hepatic expression levels of miR-199a-5p, miR-122 and miR-221 in the mice were examined. Bioinformatic analysis of dysregulated miR-199a-5p was performed to predict the potential role of miR-199a-5p in NASH. The MCD diet was found to significantly reduce miR-122 expression levels and significantly increase miR-199a-5p expression levels in mouse livers, compared with those of mice fed a control diet. In the bioinformatic analysis, miR-199a-5p was identified to be predominantly involved in transcription, protein serine/threonine kinase activity, insulin signaling, and the Wnt and mitogen-activated protein kinase signaling pathways. The regulation of nuclear receptor corepressor 1 (NCOR1) by miR-199a-5p was also examined by silencing and overexpressing this miRNA in LX-2 cells. The data revealed that NCOR1 protein levels were significantly reduced and enhanced by miR-199a-5p mimic and inhibitor, respectively. These findings suggest a key role for miR-199a-5p in the progression of NASH through inhibition of NCOR1 translation, and provide novel insights into NASH pathogenesis. [ABSTRACT FROM AUTHOR]