Abstract
XTcf-3 is a maternally expressed Xenopus homolog of the mammalian HMG box factors Tcf-1 and Lef-1. The N-terminus of XTcf-3 binds to beta-catenin. Microinjection of XTcf-3 mRNA in embryos results in nuclear translocation of beta-catenin. The beta-catenin-XTcf-3 complex activates transcription in a transient reporter gene assay, while XTcf-3 by itself is silent. N-terminal deletion of XTcf-3 (delta N) abrogates the interaction with beta-catenin, as well as the consequent transcription activation. This dominant-negative delta N mutant suppresses the induction of axis duplication by microinjected beta-catenin. It also suppresses endogenous axis specification upon injection into the dorsal blastomeres of a 4-cell-stage embryo. We propose that signaling by beta-catenin involves complex formation with XTcf-3, followed by nuclear translocation and activation of specific XTcf-3 target genes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Cytoskeletal Proteins / physiology*
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DNA, Complementary
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Embryonic Induction
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Gene Expression Regulation, Developmental*
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HMGB Proteins*
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Molecular Sequence Data
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Morphogenesis / genetics
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Morphogenesis / physiology
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Mutagenesis, Site-Directed
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Restriction Mapping
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TCF Transcription Factors
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Trans-Activators*
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Transcription Factor 3
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Transcription Factor 7-Like 1 Protein
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcription, Genetic
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Xenopus
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Xenopus Proteins
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beta Catenin
Substances
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CTNNB1 protein, Xenopus
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Cytoskeletal Proteins
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DNA, Complementary
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HMGB Proteins
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TCF Transcription Factors
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Tcf3 protein, Xenopus
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Trans-Activators
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Transcription Factor 3
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Transcription Factor 7-Like 1 Protein
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Transcription Factors
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Xenopus Proteins
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beta Catenin
Associated data
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GENBANK/X99308
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GENBANK/X99309
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GENBANK/X99310
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GENBANK/X99311