Constitutive activation of ß-catenin in ameloblasts leads to incisor enamel hypomineralization.

Enamel is the hardest tissue with the highest degree of mineralization protecting the dental pulp from injury in vertebrates. The ameloblasts differentiated from ectoderm-derived epithelial cells are a single cell layer and are important for the enamel formation and mineralization. Wnt/ß-catenin signaling has been proven to exert an important role in the mineralization of bone, dentin and cementum. Little was known about the regulatory mechanism of Wnt/ß-catenin signaling pathway in ameloblasts during amelogenesis, especially in the mineralization of enamel. To investigate the role of ß-catenin in ameloblasts, we established Amelx-Cre; ß-catenin∆ex3fl/fl (CA-ß-catenin) mice, which could constitutive activate ß-catenin in ameloblasts. It showed the delayed mineralization and eventual hypomineralization in the incisor enamel of CA-ß-catenin mice. Meanwhile, the amelogenesis-related proteinases Mmp20 and Klk4 were decreased in the incisors of CA-ß-catenin mice. These data indicated that ß-catenin plays an essential role in differentiation and function of ameloblasts during amelogenesis.