Hindbrain patterning: FGFs regulate Krox20 and mafB/kr expression in the otic/preotic region.
Krox20 and mafB/kr are regulatory genes involved in hindbrain segmentation and anteroposterior (AP) patterning. They are expressed in rhombomeres (r) r3/r5 and r5/r6 respectively, as well as in the r5/r6 neural crest. Since several members of the fibroblast growth factor (FGF) family are expressed in the otic/preotic region (r2-r6), we investigated their possible involvement in the regulation of Krox20 and mafB/kr. Application of exogenous FGFs to the neural tube of 4- to 7-somite chick embryos led to ectopic expression in the neural crest of the somitic hindbrain (r7 and r8) and to the extension of the Krox20- or mafB/kr-positive areas in the neuroepithelium. Application of an inhibitor of FGF signalling led to severe and specific downregulation of Krox20 and mafB/kr in the hindbrain neuroepithelium and neural crest. These data indicate that FGFs are involved in the control of regional induction and/or maintenance of Krox20 and mafB/kr expression, thus identifying a novel function for these factors in hindbrain development, besides their proposed more general role in early neural caudalisation.
Marín
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Unité 368 de l'Institut National de la Santé et de la Recherche Médicale, Ecole Normale Supérieure, 75230 Paris Cedex 05, France.
Charnay
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D000818:Animals; D030161:Avian Proteins; D019521:Body Patterning / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002642:Chick Embryo; D002678:Chimera; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D051767:Early Growth Response Protein 2; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D051519:Fibroblast Growth Factor 4; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D017403:In Situ Hybridization; D051258:MafB Transcription Factor; D009432:Neural Crest / Q000187:drug effects / Q000637:transplantation; D015513:Oncogene Proteins / Q000235:genetics* / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000494:pharmacology; D011784:Quail; D011994:Recombinant Proteins / Q000494:pharmacology; D012249:Rhombencephalon / Q000187:drug effects / Q000196:embryology*; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*
D030161:Avian Proteins; D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; D051519:Fibroblast Growth Factor 4; D051258:MafB Transcription Factor; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C091157:maf-B protein, chicken; D016222:Fibroblast Growth Factor 2; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors