title: Antagonism between β-catenin and Gata.a sequentially segregates the germ layers of ascidian embryos.
abstract: Many animal embryos use nuclear β-catenin (nβ-catenin) during the segregation of endomesoderm (or endoderm) from ectoderm. This mechanism is thus likely to be evolutionarily ancient. In the ascidian embryo, nβ-catenin reiteratively drives binary fate decisions between ectoderm and endomesoderm at the 16-cell stage, and then between endoderm and margin (mesoderm and caudal neural) at the 32-cell stage. At the 16-cell stage, nβ-catenin activates endomesoderm genes in the vegetal hemisphere. At the same time, nβ-catenin suppresses the DNA-binding activity of a maternal transcription factor, Gata.a, through a physical interaction, and Gata.a thereby activates its target genes only in the ectodermal lineage. In the present study, we found that this antagonism between nβ-catenin and Gata.a also operates during the binary fate switch at the 32-cell stage. Namely, in marginal cells where nβ-catenin is absent, Gata.a directly activates its target, Zic-r.b (ZicL), to specify the marginal cell lineages. Thus, the antagonistic action between nβ-catenin and Gata.a is involved in two consecutive stages of germ layer segregation in ascidian embryos.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.|Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kaoru S
authors.initials: KS
authors.lastname: Imai
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France.
authors.forename: Clare
authors.initials: C
authors.lastname: Hudson
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Oda-Ishii
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France yasuo@obs-vlfr.fr yutaka@ascidian.zool.kyoto-u.ac.jp.
authors.forename: Hitoyoshi
authors.initials: H
authors.lastname: Yasuo
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan yasuo@obs-vlfr.fr yutaka@ascidian.zool.kyoto-u.ac.jp.
authors.forename: Yutaka
authors.identifier: 0000-0001-5193-0708
authors.initials: Y
authors.lastname: Satou
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics*; D019070:Cell Lineage / Q000235:genetics; D002938:Ciona intestinalis / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian; D050982:GATA1 Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D005855:Germ Layers / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D014561:Urochordata / Q000196:embryology / Q000235:genetics; D051176:beta Catenin / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: D050982:GATA1 Transcription Factor; D051176:beta Catenin
keywords: Ascidian; Ciona intestinalis; Gata; Germ layer formation; Zic; β-Catenin