The Mechanism Of GSTM2 Regulating Nonalcoholic Steatohepatitis And Study Of FTZ Intervention

Objective: Nonalcoholic fatty liver disease(NAFLD)has become the most common chronic liver disease all over the world,including a broad spectrum of diseases ranging from steatosis to nonalcoholic steatohepatitis(NASH),which is considered to be the main cause of end-stage liver injury.Glutathione S-transferases(GSTs)are a class of phase II detoxification enzymes,which catalyze the binding of glutathione(GSH)with a variety of exogenous substances and metabolites.Glutathione S-transferase Mu2(GSTM2)is a Mu isoenzyme of GST,and its role in the progress of NASH is unclear.Compound Zhen zhu Tiao zhi(FTZ)is a representative prescription and clinical experience prescription of traditional Chinese medicine theory in the prevention and treatment of Glucolipid Metabolic Disorders.Previous studies have confirmed that FTZ has the effect of treating nonalcoholic fatty liver disease.FTZ can treat NAFLD by inhibiting oxidative stress,inflammation,fibrosis and regulating lipid metabolism,which may be related to the regulation of GSTM2 and ASK1 signaling pathway.Therefore,this study aims to explore the role of GSTM2 in nonalcoholic fatty liver disease and the possible therapeutic effect of compound Zhen zhu Tiao zhi(FTZ)on nonalcoholic fatty liver disease through GSTM2.Methods: 1.Establish a variety of non-alcoholic fatty liver animal models,and the expression of GSTM2 was detected by Western blot,q PCR and immunofluorescence.2.We first performed gain-of-function and lossof-function assays to establish L02 hepatocyte lines with GSTM2 overexpression and silencing to detect the expression of inflammation,lipid metabolism and fatty acid oxidation related genes.3.The liver specific knockout mice were induced by high-fat diet(HFD)and high-fat/highcholesterol(HFHC)diet respectively.The expression of GSTM2 could affect the liver steatosis in pathological mice model,and confirm the role of GSTM2 in metabolic fatty degeneration.In order to confirm the role of GSTM2 in NASH,GSTM2-HTG mice were used to detect the effect of GSTM2 overexpression on NASH progress in pathological mice.4.In order to further study the molecular regulation mechanism of GSTM2 affecting ASK1 and its downstream pathway,Co-IP experiment,immunofluorescence and Western blot were carried out to investigate the role of GSTM2 and ASK1 signaling pathway,and study the effect of GSTM2 on NASH progress.5.C57 mice were induced by high fat diet,and then treated with different doses of FTZ(0.6g/kg and 1.2g/kg),and the expression of GSTM2 and ASK1 related signal pathway was detected.Results: 1.We confirmed that glutathione S-transferase Mu 2(GSTM2)is a sensitive responder and an effective inhibitor of NASH progression.We found that GSTM2 was significantly down regulated during NASH progression.2.In vitro and in vivo,GSTM2 can significantly reduce insulin resistance,hepatic steatosis,inflammation and fibrosis induced by high-fat diet and high-fat / high cholesterol diet.3.In mechanism,GSTM2 maintains MAPK pathway by directly interacting with ASK1.In addition,GSTM2 directly binds to the N-terminal region of ASK1 and inhibits the dimerization of ASK1,thereby inhibiting the phosphorylation of ASK1 and the activation of its downstream p38 signaling pathway.4.FTZ inhibits the progression of NASH by improving the expression of GSTM2 and regulating ASK1 signaling pathway.Conclusion: 1.GSTM2 is an endogenous inhibitor,which inhibits the progression of NASH by blocking the dimerization and phosphorylation of ASK1.2.FTZ can treat NAFLD by regulating GSTM2 expression and mediating ASK1 signaling pathway.