Abstract: Objective The aim of this experiment was to investigate Notch family and lipid metabolism changes in LO2 cells with adipogenesis in vitro. Methods Palmitic acid (PA) was used to intervene human hepatocytes (L02 cells) to construct an in vitro steatosis cell model. The L02 cells were cultured with different concentrations (0 mM, 0.1 mM, 0.25 mM and 0.5 mM) of PA and different concentrations 0μM, 1μM, 2μM, 5μM and 10 μM) of γ secretase inhibitors N--S-phenylycine t-butyl ester (DAPT ) in 0.25mM PA-intervened cells for 24 h. The cells at 0 mM PA culture was used as the control group and those with 0 μM DAPT culture was defined as the model group. The Notch family(Notch 1,2 and 3)and its downstream genes(Hes-1 and Hey-1) mRNA levels were detected by real-time quantitative PCR. The aspartate aminotransferase (AST) and alanine transaminase(ALT) levels in supernatants, the cell triglyceride(TG), cholesterol(TC) and free fatty acid (FFA) levels were measured by colorimetric method. Results In 0.25 mM and 0.5 mM PA-intervened cells, the Notch3 mRNA levels were (0.6±0.2) and (0.4±0.1), respectively, both significantly lower than in the controlled cells, and the Hes-1 mRNA levels were (1.7±0.2) and (1.5±0.1), significantly higher than in the control; the AST levels in the supernatants were (6.7±2.6) U/L and (12.4±1.6) U/L , significantly higher than in the control, and the ALT levels were (5.7±0.8) U/L and (10.3±0.7) U/L, significantly higher than[(2.2±0.3) U/L, P<0.01] in the control; the cell TG levels were (0.4±0.04) mmol/g and (0.4±0.04) mmol/g, significantly higher than in the control; the Notch1 mRNA, TC and FFA levels in cells at 0.5mM PA intervention were (1.9±0.1), (1.2±0.4) mmol/g and (0.07±0.004) mmol/g, significantly higher than in the control; after 24 hour treatment with 2 μM DAPT, the Hes-1 mRNA, Hey-1 mRNA, AST and TG levels were (0.5±0.1), (0.6±0.3), (6.4±2.9) U/L and (0.03±0.01) mmol/g, with 5 μM DAPT intervention were (0.4±0.2), (0.6±0.1), (7.3±1.3) U/L and (0.04±0.01) mmol/g, and with 10 μM DAPT culture were (0.3±0.2), (0.4±0.1), (4.9±0.7) U/L and (0.02±0.01) mmol/g, all significantly lower than in model cells; the cell TC level was (0.2±0.03) mmol/g in 10 μM DAPT intervention, significantly higher than in the model. Conclusion Inhibition of Notch signaling could effectively improve cell injures in adipogenic cells, suggesting that the Notch signaling pathway might be closely related to lipid metabolism in hepatocytes intro, which is worthy of further study.

Key words: L02, Notch family, γ-secretase inhibitors, Palmitic acid, In vitro