Resveratrol Attenuates High-Fat Diet-Induced Hepatic Lipotoxicity by Upregulating Bmi-1 Expression

Resveratrol (RES), a natural polyphenol phytoalexin, has been reported to attenuate nonalcoholic fatty liver disease (NAFLD). However, its roles on protection of liver from lipotoxicity and underlying mechanism are not fully understood. In this study, we investigated the impacts of RES on alleviating hepatic lipotoxicity and corresponding molecular mechanism. Impacts of RES on oleic acid (OA)-induced lipotoxicity were assessed in L02 cells and C57BL/6J mice, respectively. In L02 cells, lipotoxicity was assessed by detection of apoptosis, mitochondrial function, oxidative stress and ROS-related signaling. In mice, lipotoxicity was evaluated by detecting hepatic function, serum enzyme activity, and reactive oxygen species (ROS) levels. We found that RES reduced OA-induced apoptosis, mitochondrial dysfunction, ROS generation, and DNA damage in L02 cells. RES also decreased expression of cleaved caspase-3 and p53 and increased expression of B-cell lymphoma 2 (Bcl-2). Importantly, RES protected mice from high-fat diet-induced hepatic lipotoxicity, demonstrated by reduced ROS levels and lipid peroxidation. Mechanically, B lymphoma Mo-MLV insertion region 1 (Bmi-1) expression and antioxidative superoxide dismutase were increased after RES treatment. Further mechanistic analysis indicated that protection effects of RES against OA-induced lipotoxicity were abrogated by Bmi-1 small interference RNA (siRNA) in L02 cells. SIGNIFICANCE STATEMENT: Results from clinical studies about the effect of RES on NAFLD are inconsistent and inconclusive. This study confirms the protective role of RES as an anti-ROS agent and its ability to alleviate DNA damage through a pathway involving p53/p21 signaling. Further mechanistic analysis indicated that protection effects of RES were relative with Bmi-1. This is the first study on the role of Bmi-1 in the pathogenesis of NAFLD and the target of resveratrol against NAFLD.