Activation of Wnt signaling in Axin2 cells leads to osteodentin formation and cementum overgrowth.

Objectives: In this study, we used the mouse incisor model to investigate the regulatory mechanisms of Wnt/β-catenin signaling on Axin2 cells in tooth development.

Materials And Methods: Axin2 reporter mice were used to define the expression pattern of Axin2 in mouse incisors. We traced the fate of Axin2 cells from postnatal Day 21 (P21) to P56 using Axin2 and R26R reporter mice. For constitutive activation of Wnt signaling, Axin2 , β-catenin , and R26R (CA-β-cat) mice were generated to investigate the gain of function (GOF) of β-catenin in mouse incisor growth.

Results: The X-gal staining of Axin2 reporter mice and lineage tracing showed that Axin2 was widely expressed in dental mesenchyme of mouse incisors, and Axin2 cells were essential cell sources for odontoblasts, pulp cells, and periodontal ligament cells. The constitutive activation of Wnt signaling in Axin2 cells resulted in the formation of osteodentin featured with increased DMP1 and dispersed DSP expression and overgrowth of cementum.

Conclusion: Wnt signaling plays a key role in the differentiation and maturation of Axin2 cells in mouse incisors.