title: FoxD3 regulation of Nodal in the Spemann organizer is essential for Xenopus dorsal mesoderm development.
abstract: Induction and patterning of the mesodermal germ layer is a key early step of vertebrate embryogenesis. We report that FoxD3 function in the Xenopus gastrula is essential for dorsal mesodermal development and for Nodal expression in the Spemann organizer. In embryos and explants, FoxD3 induced mesodermal genes, convergent extension movements and differentiation of axial tissues. Engrailed-FoxD3, but not VP16-FoxD3, was identical to native FoxD3 in mesoderm-inducing activity, indicating that FoxD3 functions as a transcriptional repressor to induce mesoderm. Antagonism of FoxD3 with VP16-FoxD3 or morpholino-knockdown of FoxD3 protein resulted in a complete block to axis formation, a loss of mesodermal gene expression, and an absence of axial mesoderm, indicating that transcriptional repression by FoxD3 is required for mesodermal development. FoxD3 induced mesoderm in a non-cell-autonomous manner, indicating a role for secreted inducing factors in the response to FoxD3. Consistent with this mechanism, FoxD3 was necessary and sufficient for the expression of multiple Nodal-related genes, and inhibitors of Nodal signaling blocked mesoderm induction by FoxD3. Therefore, FoxD3 is required for Nodal expression in the Spemann organizer and this function is essential for dorsal mesoderm formation.
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Steiner
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Engleka
authors.forename: Qun
authors.initials: Q
authors.lastname: Lu
authors.forename: Eileen C
authors.initials: EC
authors.lastname: Piwarzyk
authors.forename: Sergey
authors.initials: S
authors.lastname: Yaklichkin
authors.forename: Julie L
authors.initials: JL
authors.lastname: Lefebvre
authors.forename: James W
authors.initials: JW
authors.lastname: Walters
authors.forename: Liliam
authors.initials: L
authors.lastname: Pineda-Salgado
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Labosky
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Kessler
mesh_terms: D000818:Animals; D019521:Body Patterning; D043344:Chordata / Q000196:embryology; D004627:Embryonic Induction; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D005775:Gastrula / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000502:physiology*; D055457:Nodal Protein; D020897:Organizers, Embryonic / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D055457:Nodal Protein; D012097:Repressor Proteins; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C491003:foxd3b-A protein, Xenopus