MicroRNA-124a/Sirtuin 1 pathway inhibits autophagy to promote hepatocyte apoptosis in acute-on-chronic liver failure.

Abstract

Background: The roles of microRNAs in the regulation of autophagy and apoptosis in hepatic cells suggest that they may serve as novel biomarkers or therapeutic targets for various liver injuries. In this study, we aim to analyze whether miR-124a regulates autophagy and apoptosis in hepatic cells, particularly in acute-on-chronic liver failure (ACLF).

Materials and methods: The plasma and liver tissues from the healthy control (HC) and ACLF patients were included. Moreover, LO2 cells were used to perform in vitro experiments. To measure hepatocyte apoptosis, a TUNEL kit was used. LPS, over-expression or knockdown, 3-methyladenine (3-MA) were used in vitro experiments. The expression levels of the autophagy related proteins (Beclin-1 and LC3), anti-apoptotic proteins (BAX and Bcl-2), Sirtuin 1 (SIRT1), and miR-124a were assessed using western blotting, ELISA, and qRT-PCR.

Results: ACLF patients had significantly decreased expressions of SIRT1, Bcl-2, LC3, and Beclin-1 and significant upregulation of miR-124a and BAX in both plasma and liver tissues in comparison with the HC group. miR-124a was inversely correlated with autophagy markers and SIRT1, but positively correlated with apoptosis. Upon exposure to LPS, the levels of BAX and miR-124a were notably elevated, while Beclin-1, LC3, SIRT1, and Bcl-2 were notably downregulated in LO2 cells. These changes were further exaggerated in the presence of the miR-124a mimic and EX-527 compared to the miR-124a inhibitor and SRT1720 groups. Co-transfection of miR-124a inhibitor was able to partly counteract the pro-apoptotic effects of the autophagy inhibitor 3-MA.

Conclusion: miR-124a downregulates SIRT1, thereby suppressing hepatocyte autophagy and consequently inducing apoptosis.