Nodal regulates neural tube formation in the Ciona intestinalis embryo.
Overexpression of a lefty orthologue, Ci-lefty, caused a failure of neural tube closure in the protochordate ascidian Ciona intestinalis. The body bent dorsally, and anterior-posterior elongation was inhibited. A similar phenotype was observed in embryos treated with SB431542, an inhibitor of Nodal receptors, suggesting that Ci-Lefty antagonized Nodal signaling as reported in other deuterostome species. Overexpression of Ci-nodal also resulted in a similar phenotype, suggesting that a correct quantity and/or a spatial restriction of Nodal signaling are important for the neural tube to form. In addition to known Ci-Nodal target genes, orthologues of Zic (Ci-ZicL) and cdx (Ci-cdx) were activated by Ci-Nodal. Expression of a dominant negative Ci-cdx caused defects in neural tube formation similar to those obtained on treatment with SB431542 or overexpression of Ci-lefty. A regulatory cascade composed of Ci-Nodal, Ci-ZicL, and Ci-Cdx may play an important role in neural tube formation in the Ciona embryo.
Mita
Kaoru
K
Department of Materials Science, Kochi University, 2-5-1 Akebono-cho, Kochi-shi, Kochi 780-8520, Japan. b06d3a05@s.kochi-u.ac.jp
Fujiwara
Shigeki
S
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D002938:Ciona intestinalis / Q000196:embryology* / Q000235:genetics*; D004625:Embryo, Nonmammalian; D047108:Embryonic Development / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D055458:Left-Right Determination Factors; D008954:Models, Biological; D008969:Molecular Sequence Data; D054259:Neural Tube / Q000254:growth & development* / Q000378:metabolism; D055457:Nodal Protein; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology*
D018398:Homeodomain Proteins; D055458:Left-Right Determination Factors; D055457:Nodal Protein; D016212:Transforming Growth Factor beta