Effects Of α-Linolenic Acid And Arachidonic Acid On CYP7A1 Expression Through Nrf2 In HepG2

Non-alcoholic fatty liver disease(NAFLD) is a clinical metabolic syndrome without a history of excessive alcohol consumption. NAFLD is characterized by the accumulation of neutral lipids,including three acyl glycerol, cholesterol, fatty acids and ester. Causes of the disease are various, but does not include alcohol damage and clear liver injury factors.NAFLD is the most common liver abnormality in western countries. It is closely linked to obesity, metabolic syndrome, and type 2diabetes, and is rapidly becoming a major cause of liver failure and the need for liver transplantation. In the disease process in NAFLD, fatty acid metabolic abnormalities will lead to oxidative stress and lipid peroxidation, resulting in the antioxidant response of central regulation the expression of Nrf2 increased significantly.At the same time, through laboratory test, the expression of drug metabolizing enzyme CYP7A1 decreased significantly, and the alpha linolenic acid and arachidonic acid abnormal increase in the NAFLD model in mouse liver. In order to study the relationship between the expression of CYP7A1 and the abnormal metabolism of fatty acids, and whether the expression of CYP7A1 is regulated by Nrf2, the experiment is carried out as follows:HepG2 cells were transiently transfectedwith specific Nrf2 siRNA and pcDNA expression vector to construct cell model of Nrf2 silencing and overexpressing.HepG2 cells were cultured with ALA and AA to analysis the impact on the amount of mRNA and protein expression of Nrf2 and CYP7A1. By Nrf2 silencing and over expression cell model to detect after two kinds of fatty acids ALA and AA induced for 24 h, the changes of expression of CYP7A1 mRNA and protein in HepG2 cells. To investigate whether the change of CYP7A1 is related to Nrf2 in the case of fatty acid, and then analyze the effect of Nrf2 on CYP7A1.Determination of the concentration of ALA and AA is 0.25mmol/L, 0.5mmol/L and 1mmol/Lin the experiment by MTT method. Compared with the blank control group, the expression of Nrf2 mRNA and protein was increased after fatty acid induced with a dose dependent. When HepG2 cells were induced by ALA, the expression of CYP7A1 mRNA and protein was increased with a dose dependent.While HepG2 cells were induced by AA, the expression of CYP7A1 mRNA and protein was decreased with a dose dependent. When Nrf2 was silencing after transfected with si-Nrf2, CYP7A1 expressions have the same trend compared with the control group but the level of each expression has actually increased. When Nrf2 was over-expressed, the expressions of CYP7A1 also had the same trendcompared with the control group but the expression levels of both groups were down-regulated.The results showed that ALA and AA induced HepG2 cells, Nrf2 and CYP7A1 wereregulated.