title: The balance of WNT and FGF signaling influences mesenchymal stem cell fate during skeletal development.
abstract: Craniosynostosis, a developmental disorder resulting from premature closure of the gaps (sutures) between skull bones, can be caused by excessive intramembranous ossification, a type of bone formation that does not involve formation of a cartilage template (chondrogenesis). Here, we show that endochondral ossification, a type of bone formation that proceeds through a cartilage intermediate, caused by switching the fate of mesenchymal stem cells to chondrocytes, can also result in craniosynostosis. Simultaneous knockout of Axin2, a negative regulator of the WNT-beta-catenin pathway, and decreased activity of fibroblast growth factor (FGF) receptor 1 (FGFR1) in mice induced ectopic chondrogenesis, leading to abnormal suture morphogenesis and fusion. Genetic analyses revealed that activation of beta-catenin cooperated with FGFR1 to alter the lineage commitment of mesenchymal stem cells to differentiate into chondrocytes, from which cartilage is formed. We showed that the WNT-beta-catenin pathway directly controlled the stem cell population by regulating its renewal and proliferation, and indirectly modulated lineage specification by setting the balance of the FGF and bone morphogenetic protein pathways. This study identifies endochondral ossification as a mechanism of suture closure during development and implicates this process in craniosynostosis.
authors.affiliation: Department of Biomedical Genetics, Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Maruyama
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Mirando
authors.forename: Chu-Xia
authors.initials: CX
authors.lastname: Deng
authors.forename: Wei
authors.initials: W
authors.lastname: Hsu
mesh_terms: D000818:Animals; D060466:Axin Protein; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D020219:Chondrogenesis; D003398:Craniosynostoses / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism; D007150:Immunohistochemistry; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012886:Skull / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D060466:Axin Protein; C111729:Axin2 protein, mouse; D019485:Bone Morphogenetic Proteins; D003598:Cytoskeletal Proteins; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D051176:beta Catenin; D005346:Fibroblast Growth Factors; C496349:Fgfr1 protein, mouse; D051496:Receptor, Fibroblast Growth Factor, Type 1