Expression of Pax-3 in the lateral neural plate is dependent on a Wnt-mediated signal from posterior nonaxial mesoderm.
During early patterning of the vertebrate neuraxis, the expression of the paired-domain transcription factor Pax-3 is induced in the lateral portions of the posterior neural plate via posteriorizing signals emanating from the late organizer and posterior nonaxial mesoderm. Using a dominant-negative approach, we show in explant assays that Pax-3 inductive activities from the organizer do not depend on FGF, retinoic acid, or XWnt-8, either alone or in combination, suggesting that the organizer may produce an unknown posteriorizing factor. However, Pax-3 inductive signals from posterior nonaxial mesoderm are Wnt-dependent. We show that Pax-3 expression in the lateral neural plate expands in XWnt-8-injected embryos and is blocked by dominant-negative XWnt-8. Similarly, we show that the homeodomain transcription factor Msx-1, which like Pax-3 is an early marker of the lateral neural plate, is induced by posterior nonaxial mesoderm and blocked by dominant-negative XWnt-8. Finally, we show that Rohon-Beard primary neurons, a cell type that develops within the lateral neural plate, are also blocked in vivo by dominant-negative Xwnt-8. Together these data support a model in which patterning of the lateral neural plate by Wnt-mediated signals is an early event that establishes a posteriolateral domain, marked by Pax-3 and Msx-1 expression, from which Rohon-Beard cells and neural crest will subsequently arise.
Bang
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AG
Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California, 92037, USA.
Papalopulu
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N
Goulding
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MD
Kintner
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C
D000818:Animals; D002642:Chick Embryo; D002678:Chimera; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004475:Ectoderm / Q000502:physiology; D004627:Embryonic Induction; D018398:Homeodomain Proteins / Q000096:biosynthesis*; D017403:In Situ Hybridization; D008648:Mesoderm / Q000502:physiology; D008675:Metamorphosis, Biological; D009024:Morphogenesis; D009420:Nervous System / Q000196:embryology*; D009432:Neural Crest / Q000196:embryology; D009475:Neurons, Afferent; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011784:Quail; D014018:Tissue Distribution; D014157:Transcription Factors / Q000096:biosynthesis*; D051153:Wnt Proteins; D029867:Xenopus Proteins; D014982:Xenopus laevis; D029961:Zebrafish Proteins
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; C489411:Pax3 protein, Xenopus; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C489412:pax3a protein, zebrafish; C495248:wnt8a protein, Xenopus; C068686:Pax3 protein, mouse