title: Essential role of osterix for tooth root but not crown dentin formation.
abstract: Tooth is made of crown and root. It is widely believed that dentin formation in crown and root uses the same regulatory mechanism. However, identification of nuclear factor 1 C (NFIC)'s unique function in determining root but not crown dentin formation challenges the old thinking. In searching for the target molecules downstream of NFIC, we unexpectedly found a sharp reduction of osterix (OSX), the key transcription factor in skeleton formation, in the Nfic knockout (Nfic-KO) tooth root. We then demonstrated a dose-dependent increase of Osx in the odontoblast cell line due to a transient transfection of Nfic expression plasmid. Studies of global and conditional Osx-KO mice revealed no apparent changes in the crown dentin tubules and dentin matrix. However, the OSX conditional KO (cKO) mice (crossed to the 2.3-kb collagen type 1 [Col1]-Cre) displayed an increase in cell proliferation but great decreases in expressions of root dentin matrix proteins (dentin matrix protein 1 [DMP1] and dentin sialophosphoprotein [DSPP]), leading to an inhibition in odontoblast differentiation, and short, thin root dentin with few dentin tubules. Compared to the Nfic-KO tooth, which contains essentially no dentin tubules and remains in a "root-less" status at adult stages, the Osx-cKO root phenotype had partially improved at the late stage, indicating that other factors can compensate for OSX function. Thus, we conclude that OSX, one of the key downstream molecules of NFIC, plays a critical role in root, but not crown, formation.
authors.affiliation: Biomedical Sciences, Texas A&M Baylor College of Dentistry, Dallas, TX, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Chunlin
authors.initials: C
authors.lastname: Qin
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Sunita P
authors.initials: SP
authors.lastname: Ho
authors.forename: Jian Q
authors.initials: JQ
authors.lastname: Feng
mesh_terms: D000818:Animals; D003804:Dentin / Q000254:growth & development*; D016326:Extracellular Matrix Proteins / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009804:Odontoblasts / Q000166:cytology; D010750:Phosphoproteins / Q000502:physiology; D012795:Sialoglycoproteins / Q000502:physiology; D000076182:Sp7 Transcription Factor; D019228:Tooth Crown; D014092:Tooth Root / Q000254:growth & development*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D000099311:Dentin Sialophosphoprotein
chemical_list: D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D012795:Sialoglycoproteins; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors; D000099311:Dentin Sialophosphoprotein; C513308:Dmp1 protein, mouse; C479466:Sp7 protein, mouse
keywords: DENTIN; NFIC; ODONTOBLAST; OSTERIX; TOOTH ROOT