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Imai KS, Kobayashi K, Kari W, Rothbächer U, Ookubo N, Oda-Ishii I, Satou Y. Gata is ubiquitously required for the earliest zygotic gene transcription in the ascidian embryo. Dev Biol 2019; 458:215-227. [PMID: 31751550 DOI: 10.1016/j.ydbio.2019.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 11/13/2019] [Accepted: 11/13/2019] [Indexed: 10/25/2022]
Abstract
In ascidian embryos, the earliest transcription from the zygotic genome begins between the 8-cell and 16-cell stages. Gata.a, a maternally expressed Gata transcription factor, activates target genes specifically in the animal hemisphere, whereas the complex of β-catenin and Tcf7 antagonizes the activity of Gata.a and activates target genes specifically in the vegetal hemisphere. Here, we show that genes zygotically expressed at the 16-cell stage have significantly more Gata motifs in their upstream regions. These genes included not only genes with animal hemisphere-specific expression but also genes with vegetal hemisphere-specific expression. On the basis of this finding, we performed knockdown experiments for Gata.a and reporter assays, and found that Gata.a is required for the expression of not only genes with animal hemisphere-specific expression, but also genes with vegetal hemisphere-specific expression. Our data indicated that weak Gata.a activity that cannot induce animal hemisphere-specific expression can allow β-catenin/Tcf7 targets to be expressed in the vegetal cells. Because genes zygotically expressed at the 32-cell stage also had significantly more Gata motifs in their upstream regions, Gata.a function may not be limited to the genes expressed specifically in the animal or vegetal hemispheres at the 16-cell stage, and Gata.a may play an important role in the earliest transcription of the zygotic genome.
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Affiliation(s)
- Kaoru S Imai
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan.
| | - Kenji Kobayashi
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Willi Kari
- Department of Evolution and Developmental Biology, Zoological Institute, University, Innsbruck, Innsbruck, Austria
| | - Ute Rothbächer
- Department of Evolution and Developmental Biology, Zoological Institute, University, Innsbruck, Innsbruck, Austria
| | - Naoki Ookubo
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, 560-0043, Japan
| | - Izumi Oda-Ishii
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
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Yang JR, Ruan S, Zhang J. Determinative developmental cell lineages are robust to cell deaths. PLoS Genet 2014; 10:e1004501. [PMID: 25058586 PMCID: PMC4110091 DOI: 10.1371/journal.pgen.1004501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 05/24/2014] [Indexed: 11/18/2022] Open
Abstract
All forms of life are confronted with environmental and genetic perturbations, making phenotypic robustness an important characteristic of life. Although development has long been viewed as a key component of phenotypic robustness, the underlying mechanism is unclear. Here we report that the determinative developmental cell lineages of two protostomes and one deuterostome are structured such that the resulting cellular compositions of the organisms are only modestly affected by cell deaths. Several features of the cell lineages, including their shallowness, topology, early ontogenic appearances of rare cells, and non-clonality of most cell types, underlie the robustness. Simple simulations of cell lineage evolution demonstrate the possibility that the observed robustness arose as an adaptation in the face of random cell deaths in development. These results reveal general organizing principles of determinative developmental cell lineages and a conceptually new mechanism of phenotypic robustness, both of which have important implications for development and evolution.
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Affiliation(s)
- Jian-Rong Yang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Shuxiang Ruan
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
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Noda T. The maternal genes Ci-p53/p73-a and Ci-p53/p73-b regulate zygotic ZicL expression and notochord differentiation in Ciona intestinalis embryos. Dev Biol 2011; 360:216-29. [PMID: 21925489 DOI: 10.1016/j.ydbio.2011.08.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 08/11/2011] [Accepted: 08/14/2011] [Indexed: 02/03/2023]
Abstract
I isolated a Ciona intestinalis homolog of p53, Ci-p53/p73-a, in a microarray screen of rapidly degraded maternal mRNA by comparing the transcriptomes of unfertilized eggs and 32-cell stage embryos. Higher expression of the gene in eggs and lower expression in later embryonic stages were confirmed by whole-mount in situ hybridization (WISH) and quantitative reverse transcription-PCR (qRT-PCR); expression was ubiquitous in eggs and early embryos. Knockdown of Ci-p53/p73-a by injection of antisense morpholino oligonucleotides (MOs) severely perturbed gastrulation cell movements and expression of notochord marker genes. A key regulator of notochord differentiation in Ciona embryos is Brachyury (Ci-Bra), which is directly activated by a zic-like gene (Ci-ZicL). The expression of Ci-ZicL and Ci-Bra in A-line notochord precursors was downregulated in Ci-p53/p73-a knockdown embryos. Maternal expression of Ci-p53/p73-b, a homolog of Ci-p53/p73-a, was also detected. In Ci-p53/p73-b knockdown embryos, gastrulation cell movements, expression of Ci-ZicL and Ci-Bra in A-line notochord precursors, and expression of notochord marker gene at later stages were perturbed. The upstream region of Ci-ZicL contains putative p53-binding sites. Cis-regulatory analysis of Ci-ZicL showed that these sites are involved in expression of Ci-ZicL in A-line notochord precursors at the 32-cell and early gastrula stages. These results suggest that p53 genes are maternal factors that play a crucial role in A-line notochord differentiation in C. intestinalis embryos by regulating Ci-ZicL expression.
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Affiliation(s)
- Takeshi Noda
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan.
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