title: The effects of Sp7/Osterix gene silencing in the chondroprogenitor cell line, ATDC5.
abstract: Chondrocytes are known to express Sp7/Osterix (Osx) to varying degrees, but the role of Osx in chondrocytes is still unknown. In the current study, we investigated the role of the Osx gene using the clonal mouse embryonic cell line ATDC5, which retains the properties of the chondroprogenitor. ATDC5 cells express Osx; therefore, the effects of Osx gene silencing with shRNA lentiviral particles on chondrocyte marker gene expression and alkaline phosphatase (ALP) activity were investigated. At confluency, gene silencing down-regulated expression of the Sox trio (Sox5, 6, 9), Dlx5 and Alp mRNA, as well as ALP enzyme activity. Bone morphogenetic protein 2 (BMP2) is known to induce Osx gene expression in chondrocytes, and stimulation with BMP2 rescued Osx expression accompanied by up-regulation of Alp expression and ALP enzyme activity in a dose-dependent manner. To clarify the role of Osx in chondrocyte differentiation, cells induced to differentiate by 10μg/ml insulin for 21days were examined. Gene silencing inhibited the expression of the hypertrophic chondrocyte marker gene, type X collagen (Col X), and attenuated up-regulation of Dlx5 and Alp mRNA, as well as ALP enzyme activity. Taken together, these results suggest that Osx is involved in chondrogenic gene activation and is a positive regulator of the chondrocyte differentiation.
authors.affiliation: Department of Anatomy, Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, 1-8-13, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. omoteyama@dent.nihon-u.ac.jp
authors.forename: Kazuki
authors.initials: K
authors.lastname: Omoteyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Takagi
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D020868:Gene Silencing; D051379:Mice; D000076182:Sp7 Transcription Factor; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors