title: Localization of runx2, osterix, and osteopontin in tooth root formation in rat molars.
abstract: Cementogenesis starts with the differentiation of cementoblasts. Mature cementoblasts secrete cementum matrix. Cementum components are similar to bone; moreover, cementoblasts possess many characteristics similar to those of osteoblasts. Runx2 and osterix, the transcriptional factors for osteoblast differentiation, participate in tooth formation. However, the characteristics of Runx2 and osterix during the differentiation process of cementoblasts remain unclear. In this study, we examined the immunolocalization patterns of Runx2, osterix, and osteopontin during rat molar tooth formation. Periodontal ligament cells and osteoblasts located on the alveolar bone surface showed immunoreactivity for Runx2. Colocalization of Runx2 and osterix was detected in cementoblasts, which penetrated the ruptured Hertwig's epithelial root sheath and attached to root dentin. Moreover, osteopontin was observed in Runx2-positive cementoblasts facing the root surface. However, the cells adjacent to cementoblasts showed only Runx2 reactivity. Neither Runx2 nor osterix was seen in cementocytes. These results suggest that both Runx2 and osterix are important for differentiation into cementoblasts. Additionally, osterix may be indispensable for transcription of osteopontin expression.
authors.affiliation: Department of Oral Morphology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. yamagata@md.okayama-u.ac.jp
authors.forename: Azumi
authors.initials: A
authors.lastname: Hirata
authors.forename: Toshio
authors.initials: T
authors.lastname: Sugahara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D003739:Dental Cementum / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D008963:Molar / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D053495:Osteopontin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014092:Tooth Root / Q000254:growth & development / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; C493717:Runx2 protein, rat; C495181:Sp7 protein, rat; D014157:Transcription Factors; D053495:Osteopontin