title: Synthesis and intracellular transportation of type I procollagen during functional differentiation of odontoblasts.
abstract: The expression of type I collagen, the most component of dentin extracellular matrix proteins (ECMs) in odontoblast is correlated with the activity of dentin formation. Since odontoblast possesses a distinct cellular process for protein transport into the dentinal tubule, it is important to examine the intracellular protein localization. However, a study focusing on odontoblast processes has not been performed. Type I collagen is synthesized as procollagen, which is immediately converted to collagen upon secretion. After characterization of antiserum to rat type I procollagen, we investigated the intracellular localization of type I procollagen in odontoblasts during and after dentinogenesis, using immunohistochemistry and in situ hybridization. The level of mRNA expression decreased during dentinogenesis, whereas the intracellular localization of type I procollagen in odontoblast processes become more distinct. The percentage of dentinal tubules with type I procollagen increased significantly with aging. Odontoblasts in pulp horn, in particular, showed moderate expression of type I procollagen after dentinogenesis. Since loss of occlusion also caused a significant decrease in type I procollagen, we concluded that occlusal stimulation activated type I procollagen synthesis in odontoblasts. We also suggest that analysis of intracellular transport of type I procollagen via odontoblast processes may be a new approach to evaluation of odontoblast function.
authors.affiliation: Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan.
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Sato
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Komaki
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kusunoki
authors.forename: Shinobu
authors.initials: S
authors.lastname: Tsuchiya
authors.forename: Naoto
authors.initials: N
authors.lastname: Haruyama
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Sasano
authors.forename: Makoto
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000378:metabolism*; D003804:Dentin / Q000166:cytology / Q000378:metabolism*; D003810:Dentinogenesis; D009804:Odontoblasts / Q000166:cytology / Q000378:metabolism*; D053495:Osteopontin / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar
chemical_list: D024042:Collagen Type I; C506897:Spp1 protein, rat; D053495:Osteopontin