title: Octacalcium phosphate suppresses chondrogenic differentiation of ATDC5 cells.
abstract: Implantation of octacalcium phosphate (OCP), a hydroxyapatite precursor, has been reported to induce chondrogenesis in vivo. In this study, we examined the effects of OCP on the chondrogenic differentiation of mouse chondroblastic ATDC5 cells in vitro. Contrary to our expectation, chondrogenic differentiation of ATDC5 cells evaluated by the mRNA expression of Col2a1, Acan and Col10a1 was suppressed by OCP. Among Sox9, Sox5 and Sox6, essential transcription factors for chondrogenesis, the expression of Sox6 mRNA was markedly lowered by OCP. Whereas ATDC5 cells dissolved OCP to liberate calcium and inorganic phosphorus, increased calcium or phosphate in the medium had little effect on the differentiation of these cells. Direct contact of ATDC5 cells with OCP was required to suppress the expression of Col2a1 and Sox6 mRNAs, whereas the introduction of Sox6 short interfering RNA lowered the expression of Col2a1 mRNA. On the other hand, the forced expression of Sox6 protein partially but significantly, restored the expression of Col2a1 mRNA suppressed by OCP. These results indicate that OCP suppresses the chondrogenic differentiation of ATDC5 cells, at least in part, at the Sox6 transcription level.
authors.affiliation: Department of Biochemistry, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Shibuya
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamada
authors.forename: Masamichi
authors.initials: M
authors.lastname: Takami
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Suzawa
authors.forename: Dai
authors.initials: D
authors.lastname: Suzuki
authors.forename: Noriharu
authors.initials: N
authors.lastname: Ikumi
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Hiura
authors.forename: Takahisa
authors.initials: T
authors.lastname: Anada
authors.forename: Osamu
authors.initials: O
authors.lastname: Suzuki
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kamijo
mesh_terms: D000818:Animals; D002130:Calcium Phosphates / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects*; D051379:Mice; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D002130:Calcium Phosphates; D014157:Transcription Factors; C022045:octacalcium phosphate