Differential distribution of competence for panplacodal and neural crest induction to non-neural and neural ectoderm.
It is still controversial whether cranial placodes and neural crest cells arise from a common precursor at the neural plate border or whether placodes arise from non-neural ectoderm and neural crest from neural ectoderm. Using tissue grafting in embryos of Xenopus laevis, we show here that the competence for induction of neural plate, neural plate border and neural crest markers is confined to neural ectoderm, whereas competence for induction of panplacodal markers is confined to non-neural ectoderm. This differential distribution of competence is established during gastrulation paralleling the dorsal restriction of neural competence. We further show that Dlx3 and GATA2 are required cell-autonomously for panplacodal and epidermal marker expression in the non-neural ectoderm, while ectopic expression of Dlx3 or GATA2 in the neural plate suppresses neural plate, border and crest markers. Overexpression of Dlx3 (but not GATA2) in the neural plate is sufficient to induce different non-neural markers in a signaling-dependent manner, with epidermal markers being induced in the presence, and panplacodal markers in the absence, of BMP signaling. Taken together, these findings demonstrate a non-neural versus neural origin of placodes and neural crest, respectively, strongly implicate Dlx3 in the regulation of non-neural competence, and show that GATA2 contributes to non-neural competence but is not sufficient to promote it ectopically.
Brain Research Institute, University of Bremen, FB2, PO Box 330440, 28334 Bremen, Germany.
Mareike
M
Pieper
Katja
K
Ahrens
Elke
E
Rink
Annette
A
Peter
Gerhard
G
Schlosser
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D004475:Ectoderm / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000502:physiology; D004627:Embryonic Induction; D050989:GATA2 Transcription Factor / Q000096:biosynthesis / Q000378:metabolism*; D054262:Gastrulation; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000378:metabolism; D009420:Nervous System / Q000196:embryology; D009432:Neural Crest / Q000196:embryology* / Q000378:metabolism; D054258:Neural Plate / Q000196:embryology*; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D029867:Xenopus Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
D019485:Bone Morphogenetic Proteins; C571370:Dlx3 protein, Xenopus; D050989:GATA2 Transcription Factor; C494714:GATA2 protein, Xenopus; D018398:Homeodomain Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins