Neural tissue in ascidian embryos is induced by FGF9/16/20, acting via a combination of maternal GATA and Ets transcription factors.
In chordates, formation of neural tissue from ectodermal cells requires an induction. The molecular nature of the inducer remains controversial in vertebrates. Here, using the early neural marker Otx as an entry point, we dissected the neural induction pathway in the simple embryos of Ciona intestinalis. We first isolated the regulatory element driving Otx expression in the prospective neural tissue, showed that this element directly responds to FGF signaling and that FGF9/16/20 acts as an endogenous neural inducer. Binding site analysis and gene loss of function established that FGF9/16/20 induces neural tissue in the ectoderm via a synergy between two maternal response factors. Ets1/2 mediates general FGF responsiveness, while the restricted activity of GATAa targets the neural program to the ectoderm. Thus, our study identifies an endogenous FGF neural inducer and its early downstream gene cascade. It also reveals a role for GATA factors in FGF signaling.
Bertrand
Vincent
V
Laboratoire de Génétique et Physiologie du Développement, IBDM, CNRS/INSERM, Université de la Méditerranée/AP de Marseille, Parc Scientifique de Luminy, Case 907, F-13288, Marseille Cedex 9, France. bertrand@ibdm.univ-mrs.fr
Hudson
Clare
C
Caillol
Danielle
D
Popovici
Cornel
C
Lemaire
Patrick
P
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015415:Biomarkers; D002938:Ciona intestinalis / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D004627:Embryonic Induction / Q000502:physiology*; D050981:Erythroid-Specific DNA-Binding Factors; D051525:Fibroblast Growth Factor 9; D005346:Fibroblast Growth Factors / Q000172:deficiency* / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism; D023421:Models, Animal; D009420:Nervous System / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D051857:Otx Transcription Factors; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D015415:Biomarkers; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D051525:Fibroblast Growth Factor 9; D018398:Homeodomain Proteins; D051857:Otx Transcription Factors; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; D005346:Fibroblast Growth Factors