title: Wnt regulation of chondrocyte differentiation.
abstract: The Wnt family of growth factors are important regulators of several developmental processes including skeletogenesis. To further investigate the role of Wnts we analysed their expression in the developing chick limb and performed functional analyses in vivo and in vitro. We found that Wnt5b and Wnt11 are restricted within the prehypertrophic chondrocytes of the cartilage elements, Wnt5a is found in the joints and perichondrium, while Wnt4 is expressed in the developing joints and, in some bones, a subset of the hypertrophic chondrocytes. These Wnts mediate distinct effects on the initiation of chondrogenesis and differentiation of chondrocytes in vitro and in vivo. Wnt4 blocks the initiation of chondrogenesis and accelerates terminal chondrocyte differentiation in vitro. In contrast, Wnt5a and Wnt5b promote early chondrogenesis in vitro while inhibiting terminal differentiation in vivo. As Wnt5b and Wnt11 expression overlaps with and appears after Indian hedgehog (Ihh), we also compared their effects with Ihh to see if they mediate aspects of Ihh signalling. This showed that Ihh and Wnt5b and Wnt11 control chondrogenesis in parallel pathways.
authors.affiliation: Department of Craniofacial Development, Guy's, King's and St Thomas' School of Dentistry, Floor 28 Guy's Tower, Guy's Hospital, London Bridge, London SE1 9RT, UK.
authors.forename: Vicki
authors.initials: V
authors.lastname: Church
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nohno
authors.forename: Claudia
authors.initials: C
authors.lastname: Linker
authors.forename: Christophe
authors.initials: C
authors.lastname: Marcelle
authors.forename: Philippa
authors.initials: P
authors.lastname: Francis-West
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000502:physiology*; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology*; D017931:DNA Primers; D004527:Egg Proteins / Q000502:physiology*; D006023:Glycoproteins / Q000502:physiology*; D053823:Hedgehog Proteins; D017403:In Situ Hybridization; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000502:physiology; D051153:Wnt Proteins
chemical_list: D017931:DNA Primers; D004527:Egg Proteins; D006023:Glycoproteins; D053823:Hedgehog Proteins; D015534:Trans-Activators; D051153:Wnt Proteins