title: XTbx1 is a transcriptional activator involved in head and pharyngeal arch development in Xenopus laevis.
abstract: The development of pharyngeal arch derivatives in mouse and zebrafish embryos depends on the activity of the transcription factor Tbx1. We cloned the Xenopus laevis orthologue of Tbx1 (XTbx1) and show that the pattern of expression is similar to that in other vertebrate species. Zygotic transcripts are first detected shortly after the mid-blastula transition and are localized to the presumptive mesoderm at mid-gastrula stages. XTbx1 expression persists in the lateral plate mesoderm at neurula stages and is found in the pharyngeal arches and otic vesicles from early tail bud stages onward. We demonstrate that XTbx1 is a transcriptional activator and that this trans-activation requires the C-terminal region of the protein. A dominant interfering mutant of XTbx1 disrupts the development of Xenopus head structures and pharyngeal arch derivatives. Lineage labeling reveals a requirement for XTbx1 function in cells that contribute to the pharyngeal mesoderm and for fgf8 expression.
authors.affiliation: Molecular Medicine Unit, Institute of Child Health, London WC1N 1EH, United Kingdom. p.ataliotis@ich.ucl.ac.uk
authors.forename: Paris
authors.initials: P
authors.lastname: Ataliotis
authors.forename: Sarah
authors.initials: S
authors.lastname: Ivins
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mohun
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Scambler
mesh_terms: D000818:Animals; D001934:Branchial Region / Q000166:cytology / Q000196:embryology*; D019070:Cell Lineage / Q000235:genetics / Q000502:physiology; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000096:biosynthesis; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008648:Mesoderm / Q000166:cytology / Q000502:physiology; D020825:T-Box Domain Proteins / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D020825:T-Box Domain Proteins; C503363:Tbx1 protein, Xenopus laevis; D029867:Xenopus Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors