Structural Study On Farnesol X Receptor And Its Agonists

Since the 21 st century,the incidence of metabolic diseases,such as diabetes and obesity,have significantly increased,while the relative research has also increased accordingly.As the most important physiological factors which regulate nutrient absorption,carbohydrate and lipid metabolism,the maintenance of bile acid homeostasis is important for both the maintenance of metabolic homeostasis and the prevention of metabolic disorders.As the major bile acid receptor,Farnesoid X Receptor is distributed in the organs related to bile acid metabolism such as liver and small intestine.Meanwhile,FXR not only regulates bile acid metabolism,but also plays a key role in lipid and glucose metabolism.Based on those characteristics,FXR has become a new potential drug target for related metabolic diseases.FXR participates in bile acid metabolism through relevant receptors: inhibiting the expression of the rate-limiting enzyme CYP7A1 in bile acid synthesis,which reduces the production of bile acids;upregulating the expression of secretion carrier BSEP in liver,which promotes the secretion of the bile acid from liver to intestine;inhibiting the expression of reabsorption protein NTCP and OATP of bile acid in liver,which decreases the concentration of hepatic bile acid;inhibiting the expression of intestinal reabsorption carrier ASBT,which decreases the reabsorption of bile acids.There are also some reports showing that small molecule ligands of FXR show therapeutic effects on various metabolic diseases,including non-alcoholic fatty liver disease,type 2 diabetes,obesity and cholestasis.Here we expressed FXR-LBD protein fragment in prokaryotic expression system,and then purified FXR protein through nickel column affinity chromatography,gel filtration chromatography and ion exchange chromatography.Some co-crystals of FXR protein and potential agonist molecules have been obtained through crystallization screening and optimization.X-ray diffraction data were collected and the structure was determined through molecular replacement method.Analysis of the complex structure between FXR and various small-molecule agonists helps further understand the mechanism between FXR and its agonists,and sets up structural foundation for the development and application of tissie-specific FXR agonists.