Objective To investigate the role of p300 in lipid metabolism disorders.Methods Bioinformatics analysis was performed to analyze the expression patterns of p300 in lipid metabolism disorder-related diseases and its correlation with SREBP-1c and downstream lipid metabolic enzymes.Immunofluorescence assay was used to detect the expression of p300 in the liver tissues of the patients with varying disease severity of non-alcoholic fatty liver disease(NAFLD).A mouse model of lipid metabolism disorder was established in male C57BL/6J mice by feeding high-fat diet(HFD)for 12 weeks.Western blotting was employed to assess p300 expression level in the liver tissues of HFD-fed mice.A cell model of lipid metabolism disorder was established in HepG2/AML-12 cells induced with free fatty acid(FFA).The effects of siRNA-mediated knockdown of p300 was observed to measure the levels of intracellular total cholesterol(TC)and triglyceride(TG),lipid deposition,and production of reactive oxygen species(ROS).Results Clinically,p300 was highly expressed in lipid metabolism disorders,and its level was positively correlated with NAFLD severity(P<0.05).Gene Set Enrichment Analysis(GSEA)revealed that p300 expression was significantly associated with fatty acid metabolism,cholesterol homeostasis,lipogenesis,PPAR signaling pathway,and peroxisome pathway.In vivo,p300 was significantly up-regulated in the livers of HFD-fed mice(P<0.01).In vitro,FFA stimulation markedly increased p300 expression in both HepG2 and AML-12 cells(P<0.01),whereas p300 knockdown significantly reduced intracellular TG and TC levels(P<0.01),attenuated lipid droplet accumulation,and reversed FFA-induced ROS elevation(P<0.01).Furthermore,p300 expression was positively correlated with the expression of SREBP-1c and its downstream key lipid synthesis enzymes.Conclusion p300 may promote hepatic lipid accumulation by acetylating and activating SREBP-1c and regulating downstream lipid metabolic enzymes,thereby affecting lipid synthesis and oxidative stress.These findings suggest that p300 may be a potential therapeutic target for lipid metabolism disorder-related diseases.