Establishment and maintenance of the border of the neural plate in the chick: involvement of FGF and BMP activity.
We have investigated the cell interactions and signalling molecules involved in setting up and maintaining the border between the neural plate and the adjacent non-neural ectoderm in the chick embryo at primitive streak stages. msx-1, a target of BMP signalling, is expressed in this border at a very early stage. It is induced by FGF and by signals from the organizer, Hensen's node. The node also induces a ring of BMP-4, some distance away. By the early neurula stage, the edge of the neural plate is the only major site of BMP-4 and msx-1 expression, and is also the only site that responds to BMP inhibition or overexpression. At this time, the neural plate appears to have a low level of BMP antagonist activity. Using in vivo grafts and in vitro assays, we show that the position of the border is further maintained by interactions between non-neural and neural ectoderm. We conclude that the border develops by integration of signals from the organizer, the developing neural plate, the paraxial mesoderm and the non-neural epiblast, involving FGFs, BMPs and their inhibitors. We suggest that BMPs act in an autocrine way to maintain the border state.
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Department of Genetics and Development, Columbia University, 701 West 168th Street, New York, NY 10032, USA.
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D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins / Q000502:physiology; D024002:HMGB Proteins; D006609:High Mobility Group Proteins / Q000235:genetics / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins; D051957:MSX1 Transcription Factor; D008648:Mesoderm / Q000502:physiology; D008959:Models, Neurological; D009420:Nervous System / Q000196:embryology*; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology; D011506:Proteins / Q000502:physiology; D055748:SOXB1 Transcription Factors; D015398:Signal Transduction; D014157:Transcription Factors; D000099176:Noggin Protein
D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors; D006023:Glycoproteins; D024002:HMGB Proteins; D006609:High Mobility Group Proteins; D018398:Homeodomain Proteins; D036341:Intercellular Signaling Peptides and Proteins; D051957:MSX1 Transcription Factor; D009687:Nuclear Proteins; D011506:Proteins; D055748:SOXB1 Transcription Factors; D014157:Transcription Factors; D000099176:Noggin Protein; C054234:chordin