title: The maternal genes Ci-p53/p73-a and Ci-p53/p73-b regulate zygotic ZicL expression and notochord differentiation in Ciona intestinalis embryos.
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.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan. noda@oist.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Noda
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002938:Ciona intestinalis / Q000166:cytology / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D005326:Fetal Proteins / Q000235:genetics; D054262:Gastrulation / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D053263:Gene Regulatory Networks; D016158:Genes, p53; D008297:Male; D008969:Molecular Sequence Data; D055495:Neurogenesis / Q000235:genetics; D009672:Notochord / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D015053:Zygote / Q000378:metabolism; D000098908:Brachyury Protein
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D005326:Fetal Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D000098908:Brachyury Protein