A gene encoding a new ONECUT class homeodomain protein in the ascidian Halocynthia roretzi functions in the differentiation and specification of neural cells in ascidian embryogenesis.
Genes encoding a novel group of homeodomain transcription factors, ONECUT class homeodomain proteins, have previously been isolated from vertebrate and insect. Among them, vertebrate HNF-6 is expressed in hepatocytes and the central nervous system during embryogenesis. Although the functions of HNF-6 in hepatocytes have been well studied, the functions of HNF-6 in the central nervous system remain unknown. In this study, we isolated HrHNF-6, which encodes a new ONECUT class homeodomain protein, from an ascidian, Halocynthia roretzi. HrHNF-6 mRNA was expressed exclusively in neural cells, just posterior to the expression of Hroth during embryogenesis. One of the functions of HrHNF-6 in neural cells is the activation of the expression of HrTBB2, the ascidian beta-tubulin gene. Another is the restriction of the expression of HrPax-258 (which is expressed in the neural tube), suggesting that HrHNF-6 functions in the specification of the neural tube. These results indicate that HrHNF-6 functions in the differentiation and regional specification of neural cells during ascidian embryogenesis.
Sasakura
Y
Y
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Makabe
K W
KW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D004625:Embryo, Nonmammalian / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D051559:Hepatocyte Nuclear Factor 6; D018398:Homeodomain Proteins / Q000737:chemistry* / Q000502:physiology*; D006801:Humans; D017403:In Situ Hybridization; D007763:Lac Operon; D051379:Mice; D008969:Molecular Sequence Data; D009432:Neural Crest / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015534:Trans-Activators / Q000502:physiology*; D014404:Tubulin / Q000096:biosynthesis; D014561:Urochordata / Q000737:chemistry
D018076:DNA, Complementary; D051559:Hepatocyte Nuclear Factor 6; D018398:Homeodomain Proteins; C496605:ONECUT1 protein, human; D012333:RNA, Messenger; D015534:Trans-Activators; D014404:Tubulin