Molecular Mechanism Of MEN1/Menin Regulating Fat Metabolism In Liver Through PPARγ Pathway

In recent years,China’s dairy industry has developed rapidly,but at the same time there are many problems waiting to be solved.Non-alcoholic fatty liver disease in cattle during perinatal period is a key issue affecting the development of dairy industry.Diseased cows are prone to mastitis,ketosis,etc.,and there are greater risk of disease in the high-yield cows.This is a crucial factor for the health of dairy cows and the control of milk quality.Research at home and abroad shows that MEN1 plays a crucial role in the accumulation of TG in cow livers.The MEN1 gene is a key pathogenic gene for multiple endocrine neoplasia type 1(MEN1),menin is the coding product.It is an important transcription factor and structural adaptor protein in cells.It can participate in various biological processes in cells and regulate cell metabolism.1、In order to investigate the relationship between MEN1 and its encoded protein menin with the non-alcoholic fatty liver,we used Q-PCR technology to detect changes in the expression of MEN1 m RNA in liver tissues of cattles.In the liver tissues of cattle,we found that cows with fatty liver disease The m RNA expression of MEN1 was significantly increased(P <0.05).2、Under the premise that the PPARγ pathway has an effect on fatty liver,we examined the interaction between menin and PPARγ protein and the expression level of fatty liver-related genes downstream of PPARγ in cattles liver tissues.The results showed that Menin interacts with PPARγ protein,and PPARγ(P <0.05),FABP5(P <0.05),CPT-1(P <0.05)are significantly up-regulated in the PPARγ pathway,and other lipid metabolism genes are also up-regulated.3、In order to verify the effect of Men1 / menin on downstream genes of the PPARγ pathway,we constructed a model of Men1 overexpression and low expression in mouse liver cells,and found that Fabp3(P<0.01)and Fabp4(P<0.05)in the Men1 overexpression system The expression levels of Fabp5(P <0.05)and Cd36(P <0.05)were significantly down-regulated.4 、 Fabp3(P<0.05)and Fabp4(P<0.05)were significantly overexpressed in the Men1 low-expression system,and it was concluded that Men1 had asignificant effect on PPARγ.The expression of Fabp3,Fabp4,Fabp5 in the pathway has inhibitory effect.5、In order to explore the molecular mechanism by which menin regulates the expression of FABP3,FABP4,and FABP5 genes through PPARγ,we examined whether cows were combined with the promoters of FABP3,FABP4,and FABP5 by Ch IP in cow liver tissues.The results showed that menin could be associated with FABP3,FABP4,and FABP5 genes.Promoters are combined,and according to the difference in the amount of binding,we get that the amount of menin binding to the liver tissue of cows with fatty liver is reduced.6、We also detected the binding of menin to Fabp3,Fabp4,and Fabp5 promoters in normal mouse liver cells.It was found in the Men1 overexpression and low expression system that Men1 overexpression system compared to Men1 low expression system.Menin and Fabp3,Fabp4,Fabp5 promoter binding amount is up-regulated,this result shows that menin can regulate the gene transcription level by changing the binding amount of Fabp3,Fabp4,Fabp5 gene promoter.7、SIRT1 as an important energy regulating protein in the body,is also an important deacetylated protein.We detected that Menin can interact with SIRT1 protein in cattle liver tissue and mouse liver cells by Co IP.In order to explore the mechanism by which menin affects its transcription frontal molecule by binding to gene promoters,we examined the binding of SIRT1 to the Fabp4 gene promoter of downstream genes of PPARγ in mouse liver cells and found that SIRT1 can bind to the binding of menin to Fabp4 promoter.Same fragment.Therefore,we speculated that menin cooperates with SIRT1 to target and regulate the expression changes of Fabp3,Fabp4,and Fabp5 in the PPARγ pathway to regulate lipid deposition in hepatocytes.In summary,we found the menin protein that encoded by MEN1 gene,can act as an intermediary protein through synergistic interaction with SIRT1 protein and bind to the promoters of FABP3,FABP4,FABP5 genes through PPARγ protein,further regulating the transcription of its genes,thereby affecting liver cells lipid metabolism and the development of fatty liver in cow liver.