title: The function and regulation of TBX22 in avian frontonasal morphogenesis.
abstract: The frontonasal mass gives rise to the facial midline and fuses with the maxillary prominence to form the upper lip. Here we focus on the regulation and function of TBX22, a repressor dynamically expressed in the frontonasal mass. Both FGF and Noggin (a BMP antagonist) strongly induce gTBX22, however, each has opposite effects on morphogenesis - Noggin inhibits whereas FGF stimulates growth. To determine whether TBX22 mediates these effects, we used retroviruses to locally increase expression levels. RCAS::hTBX22 decreased proliferation, reduced expression of MSX2 and DLX5 and caused cleft lip. Decreased levels of endogenous gTBX22 were also observed but were not the primary cause of the phenotype as determined in rescue experiments. Our data suggest that genetic or environmental insults such as those affecting the BMP pathway could lead to a gain-of-function of TBX22 and predispose an individual to cleft lip.
authors.affiliation: Department of Oral Health Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
authors.forename: Norihisa
authors.initials: N
authors.lastname: Higashihori
authors.forename: Marcela
authors.initials: M
authors.lastname: Buchtová
authors.forename: Joy M
authors.initials: JM
authors.lastname: Richman
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002642:Chick Embryo; D002971:Cleft Lip / Q000209:etiology*; D005145:Face / Q000196:embryology; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D053823:Hedgehog Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D009024:Morphogenesis; D010641:Phenotype; D020825:T-Box Domain Proteins / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; C084119:MSX2 protein; D020825:T-Box Domain Proteins; D005346:Fibroblast Growth Factors