title: BMP antagonists and FGF signaling contribute to different domains of the neural plate in Xenopus.
abstract: In ectodermal explants from Xenopus embryos, inhibition of BMP signaling is sufficient for neural induction, leading to the idea that neural fate is the default state in the ectoderm. Many of these experiments assayed the action of BMP antagonists on animal caps, which are relatively naïve explants of prospective ectoderm, and different results have led to debate regarding both the mechanism of neural induction and the appropriateness of animal caps as an assay system. Here we address whether BMP antagonists are only able to induce neural fates in pre-patterned explants, and the extent to which neural induction requires FGF signaling. We suggest that some discrepancies in conclusion depend on the interpretations of sox gene expression, which we show not only marks definitive neural tissue, but also tissue that is not yet committed to neural fates. Part of the early sox2 domain requires FGF signaling, but in the absence of organizer signaling, this domain reverts to epidermal fates. We also reinforce the evidence that ectodermal explants are naïve, and that explants that lack any dorsal prepattern are readily neuralized by BMP antagonists, even when FGF signaling is inhibited.
authors.affiliation: Department of Molecular and Cell Biology and Center for Integrative Genomics, University of California, Berkeley, CA 94720-3200, USA.
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Wills
authors.forename: Vivian M
authors.initials: VM
authors.lastname: Choi
authors.forename: Margaux J
authors.initials: MJ
authors.lastname: Bennett
authors.forename: Mustafa K
authors.initials: MK
authors.lastname: Khokha
authors.forename: Richard M
authors.initials: RM
authors.lastname: Harland
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D019521:Body Patterning / Q000235:genetics; D019485:Bone Morphogenetic Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004475:Ectoderm / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D054258:Neural Plate / Q000196:embryology* / Q000378:metabolism; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics; D000099176:Noggin Protein
chemical_list: D015415:Biomarkers; D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D005346:Fibroblast Growth Factors; D055748:SOXB1 Transcription Factors; D029867:Xenopus Proteins; D000099176:Noggin Protein; C527788:Sox3 protein, Xenopus; C527781:sox2 protein, Xenopus