Autophagy is a process for the turnover of intracellular organelles and molecules during stress responses. microRNAs (miRNAs) are small, non-coding endogenous RNAs that may regulate almost every cellular process. However, the roles of miRNAs in autophagy are still poorly understood. In this study, we show that miR-26a enhances autophagy in both culture cells and the mouse liver. Hepatic overexpression of miR-26a in mice alleviated ethanol-induced hepatic steatosis and liver injury. Overexpression of miR-26a increased the expression of the autophagy mediator Beclin-1, which is regulated by mitogen-activated protein kinases (MAPKs). We identified DUSP4 and DUSP5, two MAPKs inhibitors, as direct targets of miR-26a. We further demonstrated that miR-26a targeted the 3'-UTRs of several other negative regulators of autophagy. Our results thus identify a novel miRNA-mediated mechanism that enhances cytoprotective autophagy in the liver.
Key messages: • miR-26a enhances autophagy in liver cells. • Hepatic overexpression of miR-26a in mice alleviates ethanol-induced liver injury. • Overexpression of miR-26a increases the expression of autophagy mediator Beclin-1. • DUSP4 and DUSP5, two MAPKs inhibitors, were identified as direct targets of miR-26a.
Keywords: Autophagy; Ethanol binge; Hepatic steatosis; Mitogen-activated protein kinases; miR-26a.