The Role Of RGS5 In The Mechanism Of Nonalcoholic Steatohepatitis

Purpose of the study:Non-alcoholic fatty liver disease(NAFLD)is a condition in which the liver of the patient has fat accumulation without excessive alcohol intake.As of now,the number of people with non-alcoholic fatty liver in the world accounts for more than 25% of the total population.Without effective measures,NAFLD will rapidly evolve into non-alcoholic steatohepatitis(NASH),which poses a huge threat to human life and health.According to the "multiple strike theory",the mechanism of the occurrence and development of NAFLD is complicated,and there are many factors that affect it together.This is also the difficulty of NAFLD treatment.The increasing prevalence of NAFLD / NASH has led to more and more medical resources required by patients,and there is no successful drug development for effective treatment of NAFLD / NASH,which also prompts researchers to actively explore available drug targets for the treatment of NAFLD / NASH.It is estimated that by 2025,the annual value of this drug market will reach 20 to 35 billion US dollars.The R4 / B subfamily in the RGS superfamily to which RGS5 belongs is the smallest RGS protein.RGS5 mediates a variety of cell signaling pathways in G protein and non-GPCR-dependent pathways.Studies have found that RGS5 has an important regulatory effect on innate immunity,and innate immunity plays an important role in the occurrence and development of diseases.A large amount of evidence indicates that RGS5 will have an important effect on the occurrence of diseases that mainly involve inflammation.However,most of the current research on RGS5 is focused on the reconstruction of the heart and blood vessels,atherosclerosis,etc.,and there are few reports on the effect of NASH.Therefore,the purpose of this topic is to explore the role of RGS5 in the occurrence and development of NASH,and explain how RGS5 plays a role in this process.The contents of the study are as follows:In this study,wetern blot assay was used to detect the protein expression of RGS5 in the liver of mice fed with HFHC or NC for 16 weeks.In order to further explore the role of RGS5 in liver,we constructed RGS5 knockdown cell lines,and evaluated the effect of RGS5 on liver lipid accumulation by hepatocyte oil red O staining and inflammation and lipid metabolism by RT-PCR.Then Rgs5-CKO mice were constructed to study the effect of RGS5 on liver injury induced by high-fat and high-cholesterol(HFHC)in NASH model mice.First of all,we detected the changes of the ratio of liver to body weight and the expression levels of serum ALT,AST and ALP.HE and Oil Red O staining were used to detect the degree of liver lesion,then Cd11 b,Ly6G staining was used to detect the infiltration of inflammatory cells in the liver,and real-time fluorescence quantitative PCR(RT-PCR)was used to detect the expression of genes related to lipid synthesis and decomposition,inflammation and inflammatory factors.Then the effect of RGS5 on liver fibrosis was detected by SPR and ?-SMA staining,and the fibrosis-related indexes were detected by RT-PCR.After getting the positive results,we used Western Blot to detect the effect of RGS5 on the signal pathway.Experimental results:The results showed that RGS5 protein expression level was significantly down-regulated in HFHC-induced mouse NASH model.In addition,in vitro test results show that RGS5 knockdown can significantly promote lipid accumulation and inflammatory factor expression.In animal models,RGS5 knockout mice(Rgs5-/-)aggravate HFHC-induced liver pathology,which is manifested by a marked increase in insulin tolerance and glucose tolerance;a large amount of ectopic accumulation of lipid is formed in the liver and can significantly affect lipid metabolism related gene expressions;at the same time,it aggravates the degree of liver inflammatory cell infiltration and fibrosis,and greatly increases the expression levels of genes related to inflammation and fibrosis.In the HFHC-induced model and the PA-induced cell model,RGS5 was significantly negatively correlated with MAPK-JNK1 / 2 and MAPK-p38 activation;and RGS5 could affect the TAK1 phosphorylation level.Experimental conclusion:Through in vitro and in vivo experiments,it was unanimously concluded that RGS5 has a significant inhibitory effect on the progression of NASH;and the molecular mechanism of RGS5 regulating NASH through mediating MAPK signaling was initially discussed.Although there are reports of RGS5 affecting the occurrence of other diseases,we have confirmed for the first time that RGS5 plays an important role in the occurrence of NASH,and determined the key molecular mechanism.This not only strengthens our understanding of the mechanism of NASH,but also further improves the role of natural immunity in the development of NASH.It provides new molecular targets and new ideas for drug design for the treatment of NASH.