Effects Of Palmitic Acid And Stearic Acid On The Expressions Of Heme Oxygenase 1 And Nuclear Transcription Factor Nrf2 In HepG2 Cell

Nonalcoholic fatty liver disease(NAFLD) is a class of metabolic stress disorder liver damage,closely associated with lipid peroxidation, insulin resistance, and many genetic risk factors.NAFLD is often accompanied by abnormal fatty acid metabolism, Meanwhile lipid metabolism is the characteristic performance of NAFLD, Saturated fatty acid palmitic acid(PA) and stearic acid(SA) have important physiological functions, and adequate intake can regulate hepatic lipid metabolism and prevent or treat NAFLD by inhibiting oxidative stress and inflammation.Nrf2 is a key factor cellular in anti-oxidative stress and could form Keap1_Nrf2 / ARE pathway in the nucleus interacting with antioxidant response element(ARE), inducing the expression of antioxidant enzymes and phaseâ…¡detoxifying enzyme, which plays a wide range of cell protection function in anti-tumor, anti-stress, regulating GSH synthesis, anti-apoptotic,anti-inflammatory response and neuroprotection, etc. Meanwhile, Nrf2-mediated antioxidant defense system is involved in the metabolism detoxification and transpot of many drugs. Heme oxygenase-1(HO-1) is one of Nrf2 regulated downstream target genes and an important antioxidant enzyme,which could reduce the liver damage and delay or even prevent the happening of non-alcoholic steatohepatitis to a certain extent by increasing the anti-oxidative stress of liver cells.In this experiment, HepG2 cells were transient transfected with specific Nrf2 expression plasmid and Nrf2-si RNA to construct stable cell model of Nrf2 overexpressing and silencing.Observe the change of mRNA and protein expression of HO-1 after PA and SA stimulate HepG2 cells When the expression of Nrf2 is increasing and decreasing. Clarify the correlation of Nrf2 and metabolic enzyme HO-1 After the HepG2 cells were stimulated by PA and SA.The concentration of PA and SA is determined by MTT assay screening test, the concentration was 0.25 mM, 0.5 mM, 0.75 mM and 1 mM. Compared with the control group in HepG2 cells, PA and SA induce the expression of mRNA and protein of Nrf2 and HO-1 significantly increased(P<0.05) within 1 mmol/L. When the groups was treated with PA of different concentration, Nrf2 and HO-1 mRNA and protein expression can be induced in a dose-dependent manner, while the Nrf2 and HO-1 mRNA and protein expression is increased after decreased first when treated with SA of different concentration.When Nrf2 is overexpressed, the expression of HO-1 is induced more obviously by different concentrations of PA and SA, HO-1 mRNA and protein expression levels were significantly increased(P<0.05), while when Nrf2 is silenced, the expression of HO-1is reduced by different concentrations of PA and SA, and the expression is not changed in the different concentration of PA and SA(P>0.05), which indicating that Nrf2 and HO-1 have a certain relevance in the metabolic processes of PA and SA. The purpose of the study was to master the variation rule of Nrf2 signaling pathway and its downstream target genes HO-1 with the different concentrations of PA and SA, and then guide the rational use of drugs and rational consumption related fatty acids for the prevention and treatment of liver diseases, finally, lay the theory foundation of Nrf2 as a drug target for the further study.