ApoE deficiency promotes non-alcoholic fatty liver disease in mice via impeding AMPK/mTOR mediated autophagy

Abstract

Aim: This work was to investigate the relationship between ApoE and autophagy regulated by AMPK/mTOR pathway in the pathological process of NAFLD.

Main methods: Both WT and ApoE^-/- mice were divided into two groups and allocated into either a normal chow (ND) or a high-fat diet (HFD) for 8 weeks. After that, we detected the indicators of lipid accumulation, hepatic injury, mitochondrial function hallmark, autophagy, apoptosis, inflammation, and oxidative stress by commercially available kits, immunohistochemistry, immunofluorescent staining, and western blot.

Key finding: We found the lipid levels of serum and liver, and hepatic injury were significantly increased in the ApoE^-/--HFD group compared to other groups. ApoE^-/- mice exhibited increased deposition of fat in liver tissue. The PGC1α, NRF1, ATP, p-AMPK, AMPK, Beclin1, and LC3 levels were downregulated and ROS, p-mTOR, and mTOR were increased in the ApoE^-/--HFD group compared to WT-HFD group. When treated with AMPK and autophagy activators, AICAR and rapamycin, these pathologies and protein levels can be rescued. The expression levels of apoptosis-related proteins, inflammation, and oxidative stress were increased in the ApoE^-/--HFD group compared to the WT-HFD group.

Significance: Our results indicated that ApoE deficiency can regulate AMPK/mTOR pathway, which leads to NAFLD most likely by modulating hepatic mitochondrial function.

Keywords: AMPK/mTOR; Apolipoprotein E; Autophagy; Mitochondria; NAFLD.