The Role Of Mettl3 Gene In Regulating Hepatic Lipid Oxidation In Non-alcoholic Fatty Liver Disease

[Objective]:To investigate the role of Mettl3 gene in non-alcoholic fatty liver disease by regulating oxidized lipids.[Methods]:1.Consult the statistical literature to find the breakthrough point:Studies have shown that N6-methyl(m6A)is the most common internal mRNA modification in higher eukaryotes.This process is accomplished by methyltransferase,methyltransferase-like 3(Mettl3),the best known m6A methyltransferase,which plays a role in reversible external transcriptional regulation of m6A modification,affecting biological processes including cell cycle progression,cell proliferation,cell apoptosis,cell migration and invasion,cell differentiation,and inflammatory responses.Mettl3 has also been shown to play an important regulatory role in a variety of metabolic diseases,but more mechanisms remain undiscovered in non-alcoholic fatty liver disease(NAFLD).2.The 4-week-old male C57BL/6J mice were used as experimental materials.The mice were fed high fat diet to induce obesity,and the mice were fed for 8-12 weeks to prepare NAFLD mice model.After the successful preparation of NAFLD mouse model,the specific Mettl3 small molecule inhibitor STM2457(50mg/Kg)was given daily for 14 consecutive days to observe the changes in body weight of mice.3.The metabolic system of small animals was detected 14 days after injection,and the metabolic structure of mice in each group was analyzed based on the metabolic system detection data.4.Through the detection of oxidized lipid metabolites in liver samples of mice in different groups,to explore whether different oxidized lipid metabolites exist among mice in each group.5.In vivo experiments were conducted to verify the differential oxidized lipid metabolites in mice of each group,and the possible mechanism of action of the differential metabolites in nonalcoholic fatty liver disease was preliminarily explored.[Results]:1:The expression of m6A methylation level was different in different parts of obese individuals,and increased in the liver of NAFLD individuals,regulating lipid accumulation,inflammatory infiltration and different stages of fibrosis in the liver.The level of m6A in the liver of mice treated with STM2457 was significantly decreased.2.After 14 days of continuous STM2457 treatment,the body weight of the nonalcoholic fatty liver mouse model was significantly reduced,and HE staining of the liver tissue showed that the liver fat deposition was reduced,and the shape of the liver was similar to that of normal liver.In addition,transmission electron microscopy of liver tissue showed swelling and deformation of small mitochondria in hepatocytes of mice in the high fat group,and most mitochondria in hepatocytes of mice treated with STM2457 returned to normal.3.Analysis based on the metabolic system detection data of small animals:The respiratory entropy of STM2457 group was 0.738±0.008.which was lower than that of the high-fat control group and the solvent control group(0.767±0.011 and 0.762±0.005).and the respiratory entropy of the high-fat control group and the solvent control group was lower than that of the base group(0.865±0.013).The results indicated that the lipid metabolism of NAFLD model mice treated with STM2457 was enhanced in the metabolic structure,suggesting that STM2457 may reduce lipid deposition in liver by enhancing lipid metabolism.4.Oxidative lipid metabolomics analysis was performed on liver samples of mice in different groups,and the lipid metabolism data of liver of mice in all groups were obtained by principal component analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA)to identify differentially expressed products.Further screening of the data revealed 8 different oxidative lipid metabolites,and the metabolic pathway analysis of these metabolites mainly concentrated on the arachidonic acid metabolic pathway.5.Preliminary exploration was conducted on the function of differential metabolites in the liver of NAFLD.and it was found that some of the differential metabolites could increase inflammation and promote fibrosis in NAFLD.[Conclusion]:Abnormal accumulation of liver lipids and dysfunction of lipid metabolism are the important pathological basis of NAFLD,which may lead to a series of pathological changes including oxidative stress and mitochondrial damage.In the liver of NAFLD,various lipids are one of the main sources of mitochondrial ROS and also the target of ROS attack.In NAFLD,mitochondrial function is damaged,and the normal β-oxidation function of fatty acids is impaired.Excessive lipids generate lipid mediators with multiple functions through other oxidation pathways in the damaged mitochondria,which jointly participate in the pathological process of NAFLD liver.In this study,it was found that STM2457 could reduce the level of m6A in the liver of NAFLD mice by inhibiting the activity of Mettl3 methyltransferase,so as to regulate the lipid oxidation process in the liver.The mechanism may be to improve the βoxidation function of fatty acids and increase lipid consumption by restoring the mitochondrial structure and function in the liver cells that have undergone steatosis.Reduce the influence of oxidized lipids on the further development of NAFLD.