title: Separate development of the maxilla and mandible is controlled by regional signaling of the maxillomandibular junction during avian development.
abstract: Syngnathia is a congenital craniofacial disorder characterized by bony or soft tissue fusion of upper and lower jaws. Previous studies suggested some causative signals, such as Foxc1 or Bmp4, cause the disruption of maxillomandibular identity, but their location and the interactive signals involved remain unexplored. We wanted to examine the embryonic origin of syngnathia based on the assumption that it may be located at the separation between the maxillary and mandibular processes. This region, known as the maxillomandibular junction (MMJ), is involved in segregation of cranial neural crest-derived mesenchyme into the presumptive upper and lower jaws.
  
  
  
  Here we investigated the role of Fgf, Bmp, and retinoid signaling during development of MMJ in chicken embryos. By changing the levels of these signals with bead implants, we induced syngnathia with microstomia on the treated side, which showed increased Barx1 and neural cell adhesion molecule (NCAM) expression. Redistribution of proliferating cells was also observed at the proximal region to maxillary and mandibular arch around MMJ.
  
  
  
  We propose that interactive molecular signaling by Fgfs, Bmps, and retinoids around MMJ is required for normal separation of the maxilla and mandible, as well as the proper positioning of beak commissure during early facial morphogenesis. Developmental Dynamics 246:28-40, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Tak
authors.affiliation: Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Park
authors.affiliation: Department of Oral and Maxillofacial Surgery, Stomatology Hospital of Guangzhou Medical College, GuangZhou City, China.
authors.forename: Zhenngu
authors.initials: Z
authors.lastname: Piao
authors.affiliation: Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea.|Department of Oral and Maxillofacial Surgery, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Sang-Hwy
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001717:Birds / Q000196:embryology*; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002642:Chick Embryo; D005346:Fibroblast Growth Factors / Q000378:metabolism; D008334:Mandible / Q000196:embryology / Q000254:growth & development*; D008437:Maxilla / Q000196:embryology / Q000254:growth & development*; D009024:Morphogenesis; D012176:Retinoids / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D019485:Bone Morphogenetic Proteins; D012176:Retinoids; D005346:Fibroblast Growth Factors
keywords: Barx1; Bmp4; Fgf8; NCAM; Syngnathia; maxillomandibular junction; microstomia