Site‐specific function and regulation of Osterix in tooth root formation

Abstract

Congenital diseases of tooth roots, in terms of developmental abnormalities of short and thin root phenotypes, can lead to loss of teeth. A more complete understanding of the genetic molecular pathways and biological processes controlling tooth root formation is required. Recent studies have revealed that Osterix (Osx), a key mesenchymal transcriptional factor participating in both the processes of osteogenesis and odontogenesis, plays a vital role underlying the mechanisms of developmental differences between root and crown. During tooth development, Osx expression has been identified from late embryonic to postnatal stages when the tooth root develops, particularly in odontoblasts and cementoblasts to promote their differentiation and mineralization. Furthermore, the site-specific function of Osx in tooth root formation has been confirmed, because odontoblastic Osx-conditional knockout mice demonstrate primarily short and thin root phenotypes with no apparent abnormalities in the crown (Journal of Bone and Mineral Research 30, 2014 and 742, Journal of Dental Research 94, 2015 and 430). These findings suggest that Osx functions to promote odontoblast and cementoblast differentiation and root elongation only in root, but not in crown formation. Mechanistic research shows regulatory networks of Osx expression, which can be controlled through manipulating the epithelial BMP signalling, mesenchymal Runx2 expression and cellular phosphorylation levels, indicating feasible routes of promoting Osx expression postnatally (Journal of Cellular Biochemistry 114, 2013 and 975). In this regard, a promising approach might be available to regenerate the congenitally diseased root and that regenerative therapy would be the best choice for patients with developmental tooth diseases.

Comparison of Different Decalcification Methods Using Rat Mandibles as a Model

“…Later at postnatal stages, when the root is already developed but still elongating, Runx2 expression declines while Osx expression continues to be present in the alveolar bone and in the dental pulp. 20 These findings would account for the results in the present study, in which Osx expression was identified in the osteoblast cells of the alveolar bone and in the odontoblast cells of the pulp dentinal zone of the molar teeth of the posterior samples of the mandibles treated with all decalcification methods. Interestingly, within the same samples, no Runx2 expression was visible regardless of decalcification treatment.…”

Osterixfunctions downstream of anti-Müllerian hormone signaling to regulate Müllerian duct regression

“…This suggests that Osx contributes to MD regression. Osx has wellestablished roles in osteoblast, odontoblast, and cementoblast differentiation (16,24). However, this is evidence for Osx function in sex differentiation.…”

Osterixfunctions downstream of anti-Müllerian hormone signaling to regulate Müllerian duct regression

“…This suggests that Osx contributes to MD regression. Osx has well-established roles in osteoblast, odontoblasts, and cementoblasts differentiation (16,24). However, this is the first evidence for Osx function in sex differentiation.…”