title: Beta-catenin signaling pathway is crucial for bone morphogenetic protein 2 to induce new bone formation.
abstract: Endochondral ossification is recapitulated during bone morphogenetic protein (BMP)-induced ectopic bone formation. Although BMP and beta-catenin have been investigated in bone development and in mesenchymal cells, how they interact in this process is not clear. We implanted recombinant BMP-2 into the muscle of mice to investigate the effect of beta-catenin signaling on BMP-induced in vivo endochondral bone formation. BMP-2 induced expression of several Wnt ligands and their receptors and also activated beta-catenin-mediated T cell factor-dependent transcriptional activity. An adenovirus expressing Dickkopf-1 (Dkk-1, an inhibitor of canonical Wnt pathway) inhibited beta-catenin signaling and endochondral bone formation. Interestingly, Dkk-1 inhibited both chondrogenesis and osteogenesis. Likewise, mice expressing conditional beta-catenin null alleles also displayed an inhibition of BMP-induced chondrogenesis and osteogenesis. This is in contrast to studies of embryonic skeletogenesis, which demonstrate that beta-catenin is required for osteogenesis but is dispensable for chondrogenesis. These findings suggest that embryonic development pathways are not always recapitulated during post-natal regenerative processes, and the biochemical pathways utilized to regulate cell differentiation may be different. During in vivo ectopic bone formation, BMP-2 induces beta-catenin-mediated signaling through Wnt ligands, and beta-catenin is required for both chondrogenesis and osteogenesis.
authors.affiliation: Program in Developmental Biology, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1X8, Canada.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Heather C
authors.initials: HC
authors.lastname: Whetstone
authors.forename: Andrew
authors.initials: A
authors.lastname: Youn
authors.forename: Puviindran
authors.initials: P
authors.lastname: Nadesan
authors.forename: Edwin C Y
authors.initials: EC
authors.lastname: Chow
authors.forename: Alvin C
authors.initials: AC
authors.lastname: Lin
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Alman
mesh_terms: D000483:Alleles; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002454:Cell Differentiation; D019902:Chondrocytes / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction; D014158:Transcription, Genetic; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D008024:Ligands; D011994:Recombinant Proteins; D051176:beta Catenin