biostudies-literatureOda-Ishii IJapan Science and Technology AgencyJapan Society for the Promotion of Sciencee1006045https://www.ebi.ac.uk/biostudies/studies/S-EPMC4859511biostudies-literatureUnknown12(5)Maternal factors initiate the zygotic developmental program in animal embryos. In embryos of the chordate, Ciona intestinalis, three maternal factors-Gata.a, β-catenin, and Zic-r.a-are required to establish three domains of gene expression at the 16-cell stage; the animal hemisphere, vegetal hemisphere, and posterior vegetal domains. Here, we show how the maternal factors establish these domains. First, only β-catenin and its effector transcription factor, Tcf7, are required to establish the vegetal hemisphere domain. Second, genes specifically expressed in the posterior vegetal domain have additional repressive cis-elements that antagonize the activity of β-catenin/Tcf7. This antagonizing activity is suppressed by Zic-r.a, which is specifically localized in the posterior vegetal domain anPLoS geneticsA Maternal System Initiating the Zygotic Developmental Program through Combinatorial Repression in the Ascidian Embryo.PMC485951125118510CREST15k1444725–40065Kubo AOda-Ishii IKari WSuzuki NSatou YRothbacher UfalseA Maternal System Initiating the Zygotic Developmental Program through Combinatorial Repression in the Ascidian Embryo.Maternal factors initiate the zygotic developmental program in animal embryos. In embryos of the chordate, Ciona intestinalis, three maternal factors-Gata.a, β-catenin, and Zic-r.a-are required to establish three domains of gene expression at the 16-cell stage; the animal hemisphere, vegetal hemisphere, and posterior vegetal domains. Here, we show how the maternal factors establish these domains. First, only β-catenin and its effector transcription factor, Tcf7, are required to establish the vegetal hemisphere domain. Second, genes specifically expressed in the posterior vegetal domain have additional repressive cis-elements that antagonize the activity of β-catenin/Tcf7. This antagonizing activity is suppressed by Zic-r.a, which is specifically localized in the posterior vegetal domain an2016-01-01T00:00:00Z2016 May2026-05-30T10:49:11.136Z2026-04-08T07:05:33.663ZS-EPMC48595112715262510.1371/journal.pgen.1006045