Isolation and characterization of beta-catenin downstream genes in early embryos of the ascidian Ciona savignyi.
Nuclear localization of beta-catenin is most likely the first step of embryonic axis formation or embryonic cell specification in a wide variety of animal groups. Therefore, the elucidation of beta-catenin target genes is a key research subject in understanding the molecular mechanisms of the early embryogenesis of animals. In Ciona savignyi embryos, nuclear accumulation of beta-catenin is the first step of endodermal cell specification. Previous subtractive hybridization screens of mRNAs between beta-catenin-overexpressed embryos and nuclear beta-catenin-depleted embryos have resulted in the identification of beta-catenin downstream genes in Ciona embryos. In the present study, I characterize seven additional beta-catenin downstream genes, Cs-cadherinII, Cs-protocadherin, Cs-Eph, Cs-betaCD1, Cs-netrin, Cs-frizzled3/6, and Cs-lefty/antivin. All of these genes were expressed in vegetal blastomeres between the 16-cell and 110-cell stages, although their spatial and temporal expression patterns were different from one another. In situ hybridizations and real-time PCR revealed that the expression of all of these genes was up-regulated in beta-catenin-overexpressed embryos, and down-regulated in beta-catenin-suppressed embryos. Therefore, the accumulation of beta-catenin in the nuclei of vegetal blastomeres activates various vegetally expressed genes with potentially important functions in the specification of these cells.
Imai
Kaoru S
KS
Department of Zoology Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. imai@ascidian.zool.kyoto-u.ac.jp
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019070:Cell Lineage; D017124:Conserved Sequence; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008954:Models, Biological; D008969:Molecular Sequence Data; D009025:Morpholines; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D014561:Urochordata / Q000196:embryology* / Q000235:genetics*; D051176:beta Catenin
D003598:Cytoskeletal Proteins; D009025:Morpholines; D012333:RNA, Messenger; D015534:Trans-Activators; D051176:beta Catenin