Osterix is critical for odontogenesis and condyle formation

METHODS: 1) in situ hybridization was used to examine expression patterns of osterix in condyle, pulp and odontoblast cells; 2) Radiographic, uCT, and histologic analyses were performed on newborn osterix-null mice and conditional osterix-null mice (at ages of 2- and 4-mo) deleted by CAG-CreER (a tamoxifen-inducible cre recombinase under the control of the CMV/âactin promoter) and Dmp1-Cre; and 3) Combinations of histology, SEM, x-ray and in situ hybridization methods were used to characterize phenotypes.

RESULTS: In situ hybridization showed that osterix is expressed in pulp/odontoblast cells (a similar expression level as that in bone), and the condyle (a lower level) during both embryonic and postnatal stages. Second, deletions of osterix in embryonic (by conventional knockout approach) or postnatal stage (by conditional knockout approach) led to a similar dentin defect, including thin dentin, and low mineral content. Similarly, deletions of osterix in condyle led to malformed cartilage such as an increase in condyle mass and poor organization.

CONCLUSIONS: Osterix plays important roles in odontogenesis and condyle formation during early and late development stages (Work supported by NIH grants: DE018486).