Study On The Role And Mechanism Of SUMO-Specific Protease SENP3 In Non-Alcoholic Fatty Liver Disease

Aims: Non-alcoholic fatty liver disease(NAFLD)is characterized by excessive lipid accumulation in hepatocytes.SENPs(SUMO-specific proteases),act in the protein regulatory event de-SUMOylation.SENP3,sensitive to cell stresses,regulates a diverse spectrum of biological responses.The aim of this study is to explore the role of SENP3 in NAFLD,particularly in the lipid metabolism.Methods: The expression of SENP3 in NAFLD patients,animal model and cell model were identified.Intracellular lipid accumulation was determined in SENP3 overexpressed or silenced hepatocytes with/without FFA in vitro.SENP3 related genes in steatosis were determined in vitro using RNA-Seq.Differently expressed genes generated using bioinformatics were verified in hepatocytes with qRT-PCR,in liver tissue with immunohistochemistry and in plasma with ELISA.The substrate of SENP3 was explored with immunoprecipitation.Results: SENP3 was up-regulated in the livers of NAFLD patients,rat fed with high fat diet and after loading hepatocytes with FFA.Furthermore,there was a significant correlation between hepatic SENP3 and TG.Confirming a role for SENP3,gene silencing was associated in vitro with amelioration of lipid accumulation and overexpression with enhancement of lipid accumulation.SENP3 related genes in NAFLD were determined in vitro using RNA-Seq.Eleven unique genes closely associated with lipid metabolism were generated using bioinformatics.Three selected genes(apoe,a2 m and tnfrsf11b)were verified in vitro,showing apoe,a2 m and tnfrsf11 b were regulated by SENP3 with FFA stimulation.Intrahepatic and circulating APOE,A2 M and TNFRSF11 B were elevated in NAFLD compared with controls.Results of co-immunoprecipitation in 293 T cells showed that NR4A2 was a SUMOylated(SUMO2)protein.Furthermore,SUMO2-NR4A2 in SENP3 silenced hepatocytes was shown to be much more than control,suggesting that SENP3 was a specific de-SUMOylation protease for NR4A2 in hepatocytes.Conclusions: The expression of SENP3 is increased during the development of NAFLD,which is positively correlated with lipid accumulation in the liver.SENP3 contributes to the alteration of lipid metabolism via regulating downstream genes,which have potential clinical value.The role of SENP3 in NAFLD may be achieved by de-SUMOylation of NR4A2.Such data might shed light on the diagnosis and treatmentof steatosis.The precisepathogenesis of SENP3 in NAFLD warrant further investigation using liverspecific conditional knockout mice.