β-Catenin/LEF1 activated enamelin expression in ameloblast-like cells

Enamelin is an ameloblast-specific matrix protein believed to play essential roles in enamel formation. However, mechanisms of enamelin transcription regulation are not clear. β-Catenin/LEF1 is a key transcriptional complex involved in tooth development. In this study, the role of β-catenin/LEF1 in enamelin expression was investigated. The 5′-flanking region of the mouse enamelin gene was analyzed and cloned. Co-transfection analysis and mutation assays revealed that two conserved LEF1 responsive elements located at −1002 and −597 bp upstream of the enamelin translation initiation site could augment transcriptional activity of the enamelin. The interaction between the enamelin elements and β-catenin/LEF1 was further confirmed by electrophoresis mobility shift assays and chromatin immunoprecipitation assays. In addition, LiCl treatment induced nuclear translocation of β-catenin and elevated endogenous enamelin expression in mouse ameloblast-like cells. The results suggested that Wnt/β-catenin signaling could function in enamelin gene expression by direct interaction through two conserved LEF1 responsive elements on the enamelin gene in ameloblast-like cells.