As the prevalence of type 2 diabetes melitus(T2DM)continues to increase worldwide,identifying dietary factors to reduce T2DM burden seems urgent.Increasing evidences indicate that dietary soy could improve glycamic control and insulin responsiveness,but the conclusions are still uncertain.Thioredoxin-interacting protein(Txnip),a member of the arrestin family,has emerged as a critical regulator in hyperglycemia-induced β cell apoptosis and diabetes development.S-equol,the end product of daidzein by intestinal bacteria,attracts tremendous attention as its superiority to other isoflavones in its estrogenic and antioxidant activity.In this study,the effects and mechanisms,especially on Txnip regulation,whereby S-equol exerts its beneficial effects were investigated.First,in vivo studies showed that Eq(120mg/Kg.BW)supplementation effectively decreased the blood glucose and cholesterol of Zucker diabetic fatty(ZDF)rats,and increased insulin and C-peptide,upregulated IRS-1/PI3K in pancrease and periferal tissues and UCP-2,Glut2 in pancrease were also detected.Meanwhile,in vitro studies showed that s-Eq(1-100 μM)increased glucose uptake and glucogen synthesis in HepG2 cells incubated with high glucose,and IRS-1/PI3K/Glut4 were also upregulated; while in high glucose treated INS-1 cells,improved GSIS function,reduced apoptotic cells and enhanced expression of Glut2 and UCP-2 were observed in s-Eq(1-100 μM)treated cells.All the above results indicated that s-Eq could effectively postpone the development and progression of T2DM,and might play duplicate roles in improving insulin seretion and insulin resistant.Further invetigations revealed that s-Eq supplementaion significantly inhibited the up-expression of ChREBP and Txnip in pancrease and periferal tissues of ZDF rats.And with comparsion the expression of Txnip in ChREBPsiRNA or Control-siRNA transfected in INS-1 and HepG2 cells,we confirmed that suppression ChREBP/Txnip was the important mechanism of Eq in T2DM prevention.Moreover,Eq treatment could downregulate the promoter activity of Txnip promoter with the confirmation of dmChREBP transfected HepG2 and INS-1 cells using the dual-luciferase reporter gene method.And with ChIP assay,the recruitment of Mlx,ChREBP and Pol II on ChoRE were reduced while with Eq treatment.Additionally,decreased PP2A activity and increased PKA activity were detected in Eq treatment cells.These results further suggested that Eq could inhibit Txnip expression through directly regulating PKA/PP2A balance,which would influence phosphorylation/dephosphorylation of ChREBP and further impair ChREBP-Mlx-p300 activity.