The Role Of O-GlcNAc And OGA In Liver Fat Synthesis

Objective:To investigate the mechanism of O-GlcNAcylation and OGA in the liver fat metabolism of nonalcoholic fatty liver.Methods:1.Immunohistochemistry was used to verify the expression of O-GlcNAc in NAFLD samples,establishment of NAFLD model in cell line,Western Blot was used to verify the expression of O-GlcNAc and OGA.2.Over expression of OGA lentivirus were transfected in to L0₂ cells;the OGA inhibitor PUGNAc was used to treat L0₂ cells;oil red o staining was used to detect the lipogenic ability of the models,qRT-PCR and Western Blot were used to detect the expression of SREBP1c?ACC1?FASN and SCD1.3.Co-immunoprecipitation and cycloheximide?CHX?experiments were used to verify OGA regulate SREBP1.Results:1.In 20 healthy controls,13 specimens were weakly expressed by O-GlcNAc,7specimens were strongly expressed,60 patients with NAFLD,11 specimens were weakly expressed by O-GlcNAc,and 49 specimens were Strong expression.Spearman correlation analysis r=0.441,P<0.01.In the NAFLD cell model,OGA?OGT and O-GlcNAc levels were increased.Both showed that O-GlcNAc expression was positively correlated with fat metabolism of NAFLD.2.OGA overexpression decreased L0₂ cell fat synthesis,L02 cell fat synthesis increased after OGA inhibition.After OGA overexpression,the expression of SREBP1c and the expression of fat synthase ACC1,FASN and SCD1 in L0₂ cells decreased.After OGA inhibit,the expression of OGA,OGT,O-GlcNAc,SREBP1c and the expression of fat synthase ACC1,FASN and SCD1 in L02 cells were raised.3.The results of co-immunoprecipitation indicated that OGA and SREBP1 interacted.After OGA overexpression,SREBP1 glycosylation level decreased.CHX assay showed that SREBP1c protein was degraded in 8h,suggesting that OGA affects SREBP1c protein stability.Conclusions:O-GlcNAcylation is associated with NAFLD disease,and its de-glycosidase OGA can reduce liver fat anabolism by reducing SREBP1c expression.