title: Default neural induction: neuralization of dissociated Xenopus cells is mediated by Ras/MAPK activation.
abstract: Xenopus embryonic ectodermal cells dissociated for three or more hours differentiate into neural tissue instead of adopting their normal epidermal fate. This default type of neural induction occurs in the absence of Spemann's organizer signals and is thought to be caused by the dilution of endogenous BMPs into the culture medium. Unexpectedly, we observed that BMP ligands continue to signal in dissociated cells. Instead, cell dissociation induces a sustained activation of the Ras/MAPK pathway, which causes the phosphorylation of Smad1 at sites that inhibit the activity of this transcription factor. It is this activation of Ras/MAPK that is required for neuralization in dissociated ectoderm.
authors.affiliation: Howard Hughes Medical Institute and Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662, USA.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kuroda
authors.forename: Luis
authors.initials: L
authors.lastname: Fuentealba
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ikeda
authors.forename: Bruno
authors.initials: B
authors.lastname: Reversade
authors.forename: E M
authors.initials: EM
authors.lastname: De Robertis
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004475:Ectoderm / Q000166:cytology* / Q000502:physiology; D004627:Embryonic Induction / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D009420:Nervous System / Q000196:embryology*; D009841:Oligonucleotides; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins; D013194:Staining and Labeling; D015534:Trans-Activators / Q000378:metabolism; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C497402:MXD1 protein, Xenopus; D009841:Oligonucleotides; D051785:Smad Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; D048049:Extracellular Signal-Regulated MAP Kinases; D018631:ras Proteins