Downregulation of GNAI3 Promotes the Pathogenesis of Methionine/Choline-Deficient Diet-Induced Nonalcoholic Fatty Liver Disease.

Background/aims: The pathogenesis of nonalcoholic fatty liver disease (NAFLD) has not be fully elucidated, and the lack of therapeutic strategies for NAFLD is an urgent health problem. Guanine nucleotide binding protein, alpha inhibiting activity polypeptide 3 (GNAI3) participates in several biological processes, but its relationship with lipid metabolism and NAFLD has not yet been reported. We aimed to determine the function of GNAI3 in the development of NAFLD.

Methods: Mice were fed a methionine and choline-deficient diet to induce NAFLD. An NAFLD model in HepG2 cells was induced by free fatty acid treatment. GNAI3 levels in HepG2 cells were downregulated by shRNA. Protein levels of related proteins were evaluated by Western blotting, and mRNA levels were determined by quantitative reverse transcription polymerase chain reaction. Hematoxylin and eosin and Oil Red O staining were used to observe histological changes in liver tissue.

Results: The dysregulated hepatic lipid metabolism in the NAFLD mouse model was enhanced by GNAI3 knockout, which also provoked worse liver damage. In the NAFLD model in HepG2 cells, the downregulation of GNAI3 promoted cellular lipid accumulation and enhanced the changes in lipid metabolic enzyme levels.

Conclusions: This study demonstrates that GNAI3 participates in the development of NAFLD in both cellular and mouse models. The data indicate that GNAI3 is a potential new target for the treatment of NAFLD in humans.