Abstract
The Ciona Brachyury gene (Ci-Bra) is regulated, in part, by a 434-bp enhancer that mediates restricted expression in the notochord. Here we present evidence that a Ciona Suppressor of Hairless ¿Ci-Su(H)¿ protein functions as an activator of this enhancer. Point mutations that reduce the binding of a GST/Ci-Su(H) fusion protein in vitro diminish the expression of mutagenized Ci-Bra/lacZ transgenes in electroporated embryos. Overexpression of a Ci-Su(H) fusion protein containing the Drosophila Hairy repression domain interferes with notochord differentiation, producing mutant tadpoles with shortened tails. Expression of a constitutively activated Xotch receptor in the notochord, endoderm, and CNS also alters tail morphogenesis. These results suggest that a Notch-Su(H) pathway might participate in notochord differentiation in Ciona.
Copyright 1998 Academic Press.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Brachyury Protein
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Cell Differentiation / genetics
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Ciona intestinalis / embryology*
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Cloning, Molecular
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DNA-Binding Proteins / analysis
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DNA-Binding Proteins / genetics*
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Electroporation / methods
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Enhancer Elements, Genetic / genetics
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Fetal Proteins*
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Gene Expression Regulation, Developmental / genetics*
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Histocytochemistry
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Lac Operon / genetics
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Membrane Proteins / genetics
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Molecular Sequence Data
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Notochord / growth & development
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Proteins / genetics*
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Receptors, Notch
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Recombinant Fusion Proteins / genetics
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Repressor Proteins / genetics
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Suppression, Genetic / genetics*
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T-Box Domain Proteins*
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Trans-Activators*
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Transcription Factors / genetics*
Substances
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DNA-Binding Proteins
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Fetal Proteins
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Membrane Proteins
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Proteins
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Receptors, Notch
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Recombinant Fusion Proteins
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Repressor Proteins
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Su(H) protein, Ciona intestinalis
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T-Box Domain Proteins
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Trans-Activators
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Transcription Factors
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Brachyury Protein