title: Interaction between Foxc1 and Fgf8 during mammalian jaw patterning and in the pathogenesis of syngnathia.
abstract: Syngnathia (bony fusion of the upper and lower jaw) is a rare human congenital condition, with fewer than sixty cases reported in the literature. Syngnathia typically presents as part of a complex syndrome comprising widespread oral and maxillofacial anomalies, but it can also occur in isolation. Most cartilage, bone, and connective tissue of the head and face is derived from neural crest cells. Hence, congenital craniofacial anomalies are often attributed to defects in neural crest cell formation, survival, migration, or differentiation. The etiology and pathogenesis of syngnathia however remains unknown. Here, we report that Foxc1 null embryos display bony syngnathia together with defects in maxillary and mandibular structures, and agenesis of the temporomandibular joint (TMJ). In the absence of Foxc1, neural crest cell derived osteogenic patterning is affected, as osteoblasts develop ectopically in the maxillary prominence and fuse with the dentary bone. Furthermore, we observed that the craniofacial musculature is also perturbed in Foxc1 null mice, which highlights the complex tissue interactions required for proper jaw development. We present evidence that Foxc1 and Fgf8 genetically interact and that Fgf8 dosage is associated with variation in the syngnathic phenotype. Together our data demonstrates that Foxc1 - Fgf8 signaling regulates mammalian jaw patterning and provides a mechanistic basis for the pathogenesis of syngnathia. Furthermore, our work provides a framework for understanding jaw patterning and the etiology of other congenital craniofacial anomalies, including temporomandibular joint agenesis.
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
authors.forename: Kimberly E
authors.initials: KE
authors.lastname: Inman
authors.affiliation: Department of Plastic and Oral Surgery, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Patricia
authors.initials: P
authors.lastname: Purcell
authors.affiliation: Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kume
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America ; Department of Anatomy & Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, United States of America.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Trainor
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002356:Cartilage / Q000254:growth & development / Q000473:pathology; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000235:genetics; D051524:Fibroblast Growth Factor 8 / Q000235:genetics* / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007568:Jaw / Q000473:pathology; D019767:Maxillofacial Abnormalities / Q000235:genetics* / Q000473:pathology; D051379:Mice; D009432:Neural Crest / Q000254:growth & development / Q000473:pathology; D060066:Protein Interaction Maps / Q000235:genetics; D013704:Temporomandibular Joint / Q000254:growth & development / Q000473:pathology
chemical_list: C496457:Fgf8 protein, mouse; D051858:Forkhead Transcription Factors; C112890:Foxc1 protein, mouse; D051524:Fibroblast Growth Factor 8