[EVA1A overexpression improves non-alcoholic fatty liver disease in mice by regulating lipid metabolism and promoting lipophagy].

OBJECTIVES

To investigate the role of transmembrane protein EVA1A in liver lipid metabolism and development of non-alcoholic fatty liver disease (NAFLD).

METHODS

Eight-week-old male ob/ob mice were randomized into control group injected with AAV null vector via the tail vein (AAV-null group) and AAV-Eva1a group injected with recombinant vector AAV-Eva1a (n=8). HepG2 cells transfected with the lentiviral vector LV-EVA1A or the null vector were induced with oleic acid to construct a cell model of NAFLD. The expression levels of EVA1A, lipid metabolism-related and autophagy-related genes in mouse livers were detected with RT-qPCR, Western blotting, and immunofluorescence staining, and lipid accumulation in mouse livers and blood and in the treated cells was examined with HE and Oil Red O staining and lipid detection kits. Serum levels of ALT, AST, IL-6, IL-1β, and TNF-α of the mice were detected, and hepatic lipophagy was observed with transmission electron microscopy.

RESULTS

The mouse livers in AAV-Eva1a group and LV-EVA1A-transfected cells showed significantly increased expression levels of EVA1A mRNA and protein. The liver weight and coefficient and lipid deposition of the mice with AAV-Eva1a injection and triglyceride (TG) content in LV-EVA1A-transfected cells were significantly decreased. The mice in AAV-Eva1a group showed significantly reduced serum total cholesterol, LDL-C, and HDL-C levels and hepatic TG levels with lowered serum levels of ALT, AST, IL-6 and TNF‑α. In both mouse livers in AAV-Eva1a group and LV-EVA1A-transfected HepG2 cells, acetyl-CoA carboxylase, fatty acid transport protein, and diacylglycerol acyltransferase expressions were all significantly decreased and adipose triglyceride lipase increased. Hepatic lipophagy, autophagosome numbers and LC3-II and ATG5 expressions were enhanced and p62 expression was lowered in the mice in AAV-Eva1a group and LV-EVA1A-transfected cells.

CONCLUSIONS

EVA1A overexpression alleviates fatty liver and inflammation in ob/ob mice by regulating lipid metabolism-related genes and enhancing lipophagy to promote clearance of accumulated hepatic lipids.