title: Mechanism of osteogenic induction by FK506 via BMP/Smad pathways.
abstract: FK506 is an immunosuppressant that exerts effects by binding to FK506-binding protein 12 (FKBP12). Recently, FK506 has also been reported to promote osteogenic differentiation when administered locally or in vitro in combination with bone morphogenetic proteins (BMPs), although the underlying mechanism remains unclarified. The present study initially showed that FK506 alone at a higher concentration (1muM) induced osteogenic differentiation of mesenchymal cell lines, which was suppressed by adenoviral introduction of Smad6. FK506 rapidly activates the BMP-dependent Smads in the absence of BMPs, and the activation was blocked by Smad6. Overexpression of FKBP12, which was reported to block the ligand-independent activation of BMP type I receptor A (BMPRIA), suppressed Smad signaling induced by FK506, but not that induced by BMP2. BMPRIA and FKBP12 bound to each other, and this binding was suppressed by FK506. These data suggest that FK506 promotes osteogenic differentiation by activating BMP receptors through interacting with FKBP12.
authors.affiliation: Division of Tissue Engineering, Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-8655, Japan.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Kugimiya
authors.forename: Fumiko
authors.initials: F
authors.lastname: Yano
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ohba
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Igawa
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Ung-il
authors.initials: UI
authors.lastname: Chung
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D051785:Smad Proteins / Q000378:metabolism*; D016559:Tacrolimus / Q000008:administration & dosage*
chemical_list: D019485:Bone Morphogenetic Proteins; D051785:Smad Proteins; D016559:Tacrolimus