FGF signalling controls the timing of Pax6 activation in the neural tube.
We have recently demonstrated that Pax6 activation occurs in phase with somitogenesis in the spinal cord. Here we show that the presomitic mesoderm exerts an inhibitory activity on Pax6 expression. This repressive effect is mediated by the FGF signalling pathway. The presomitic mesoderm displays a decreasing caudorostral gradient of FGF8, and grafting FGF8-soaked beads at the level of the neural tube abolishes Pax6 activation. Conversely, when FGF signalling is disrupted, Pax6 is prematurely activated in the neural plate. We propose that the progression of Pax6 activation in the neural tube is controlled by the caudal regression of the anterior limit of FGF activity. Hence, as part of its posteriorising activity, FGF8 downregulation acts as a switch from early (posterior) to a later (anterior) state of neural epithelial development.
Bertrand
N
N
Centre de Biologie du Développement, UMR 5547-CNRS-Université P. Sabatier, 31062 Toulouse cedex 04, France.
Médevielle
F
F
Pituello
F
F
D000818:Animals; D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D002490:Central Nervous System / Q000196:embryology* / Q000378:metabolism*; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D017403:In Situ Hybridization; D008648:Mesoderm / Q000378:metabolism; D009687:Nuclear Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D015398:Signal Transduction; D019170:Somites / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; C105240:CASH4 protein, Gallus gallus; C109095:Nkx1-2 protein, mouse; C000605732:Pax6 protein, mouse