Ciona intestinalis Noto4 contains a phosphotyrosine interaction domain and is involved in the midline intercalation of notochord cells.
Brachyury plays a pivotal role in the notochord formation in ascidian embryos. Ciona intestinalis Noto4 (Ci-Noto4) was isolated as a gene downstream of Ci-Bra. This gene encodes a 307 amino-acid protein with a C-terminal phosphotyrosine interaction domain (PTB/PID). Expression of Ci-Noto4 commences at the neural plate stage and is specific to notochord cells. Suppression of Ci-Noto4 levels with specific antisense morpholino oligonucleotides resulted in the formation of two rows of notochord cells owing to a lack of midline intercalation between the bilateral populations of progenitor cells. In contrast, overexpression of Ci-Noto4 by injection of a Ci-Bra(promoter):Ci-Noto4-EGFP construct into fertilized eggs disrupted the localization of notochord cells. Ci-Noto4 overexpression did not affect cellular differentiation in the notochord, muscle, mesenchyme, or nervous system. Analysis of Ci-Noto4 regions that are responsible for its function suggested significant roles for the PTB/PID and a central region, an area with no obvious sequence similarity to other known proteins. These results suggested that PTB/PID-containing Ci-Noto4 is essential for midline intercalation of notochord cells in chordate embryos.
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan. s.yamada@oist.jp
Shigehiro
S
Yamada
Naoto
N
Ueno
Nori
N
Satoh
Hiroki
H
Takahashi
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002938:Ciona intestinalis / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005326:Fetal Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009672:Notochord / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000235:genetics; D019000:Phosphotyrosine / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics; D000098908:Brachyury Protein
D005326:Fetal Proteins; D049452:Green Fluorescent Proteins; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; D019000:Phosphotyrosine; D011993:Recombinant Fusion Proteins; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein