title: Cross-regulatory interactions between Fgf8 and Shh in the avian frontonasal prominence.
abstract: The frontonasal prominence of the developing avian embryo contains an organizing center, defined by juxtaposition of the Sonic hedgehog (Shh) and Fibroblast growth factor 8 (Fgf8) expression domains. This molecular interface presages any detectable growth of the frontonasal prominence, and experiments involving transplantation of this boundary epithelium have demonstrated it is a source of dorsal-ventral and rostral-caudal patterning information for the neural crest-derived mesenchyme of the upper beak. We explored the ontogeny of this organizing center by mapping the expression domains of both genes and their receptors and downstream targets. We tested the extent to which Shh and Fgf8 regulate each other's expression in this frontonasal organizer by either blocking or ectopically activating these pathways. Our experiments revealed mutual antagonism between the two molecules, which aids in establishing and maintaining a molecular boundary that subsequently influences patterning and growth of the middle and upper face.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Arhat
authors.initials: A
authors.lastname: Abzhanov
authors.forename: Dwight R
authors.initials: DR
authors.lastname: Cordero
authors.forename: Jonaki
authors.initials: J
authors.lastname: Sen
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Tabin
authors.forename: Jill A
authors.initials: JA
authors.lastname: Helms
mesh_terms: D000818:Animals; D001502:Beak / Q000196:embryology; D019521:Body Patterning; D002642:Chick Embryo; D004475:Ectoderm / Q000196:embryology; D005145:Face / Q000196:embryology*; D051524:Fibroblast Growth Factor 8 / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D015398:Signal Transduction
chemical_list: D053823:Hedgehog Proteins; D051524:Fibroblast Growth Factor 8