title: EphA4-dependent Brachyury expression is required for dorsal mesoderm involution in the Xenopus gastrula.
abstract: Xenopus provides a well-studied model of vertebrate gastrulation, but a central feature, the movement of the mesoderm to the interior of the embryo, has received little attention. Here, we analyze mesoderm involution at the Xenopus dorsal blastopore lip. We show that a phase of rapid involution - peak involution - is intimately linked to an early stage of convergent extension, which involves differential cell migration in the prechordal mesoderm and a new movement of the chordamesoderm, radial convergence. The latter process depends on Xenopus Brachyury, the expression of which at the time of peak involution is controlled by signaling through the ephrin receptor, EphA4, its ligand ephrinB2 and its downstream effector p21-activated kinase. Our findings support a conserved role for Brachyury in blastopore morphogenesis.
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Sevan
authors.initials: S
authors.lastname: Evren
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Jason W H
authors.initials: JW
authors.lastname: Wen
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Olivia
authors.initials: O
authors.lastname: Luu
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Erich W
authors.initials: EW
authors.lastname: Damm
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Martina
authors.initials: M
authors.lastname: Nagel
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5 r.winklbauer@utoronto.ca.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Winklbauer
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D005326:Fetal Proteins / Q000378:metabolism*; D005775:Gastrula / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D017403:In Situ Hybridization; D008648:Mesoderm / Q000196:embryology*; D008855:Microscopy, Electron, Scanning; D060172:Morpholinos / Q000235:genetics; D036122:Receptor, EphA4 / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D020825:T-Box Domain Proteins / Q000378:metabolism*; D014981:Xenopus / Q000196:embryology*; D000098908:Brachyury Protein
chemical_list: D005326:Fetal Proteins; D060172:Morpholinos; D036122:Receptor, EphA4; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein
keywords: Brachyury; EphA4; Gastrulation; Involution; Xenopus