Abstract
Notch proteins are the receptors for an evolutionarily highly conserved signalling pathway that regulates numerous cell fate decisions during development. Signal transduction involves the presenilin-dependent intracellular processing of Notch and nuclear translocation of the intracellular domain of Notch, Notch-IC. Notch-IC associates with the DNA-binding protein RBP-Jkappa/CBF-1 to activate transcription of Notch target genes. In the absence of Notch signalling, RBP-Jkappa/CBF-1 acts as a transcriptional repressor through the recruitment of histone deacetylase (HDAC) corepressor complexes. We identified SHARP as an RBP-Jkappa/CBF-1-interacting corepressor in a yeast two-hybrid screen. In cotransfection experiments, SHARP-mediated repression was sensitive to the HDAC inhibitor TSA and facilitated by SKIP, a highly conserved SMRT and RBP-Jkappa-interacting protein. SHARP repressed Hairy/Enhancer of split (HES)-1 promoter activity, inhibited Notch-1-mediated transactivation and rescued Notch-1-induced inhibition of primary neurogenesis in Xenopus laevis embryos. Based on our data, we propose a model in which SHARP is a novel component of the HDAC corepressor complex, recruited by RBP-Jkappa to repress transcription of target genes in the absence of activated Notch.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing*
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Animals
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Basic Helix-Loop-Helix Transcription Factors
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cell Line
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Gene Expression
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HeLa Cells
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Histone Deacetylases / metabolism
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Homeodomain Proteins / genetics
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Humans
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Immunoglobulin J Recombination Signal Sequence-Binding Protein
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In Vitro Techniques
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Mice
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Neuropeptides / chemistry
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Neuropeptides / genetics
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Neuropeptides / metabolism*
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Nuclear Proteins*
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Phenotype
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Promoter Regions, Genetic
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Receptor, Notch1
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Receptors, Cell Surface*
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Signal Transduction
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Transcription Factor HES-1
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Transcription Factors / chemistry
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transfection
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Two-Hybrid System Techniques
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Xenopus laevis
Substances
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Adaptor Proteins, Signal Transducing
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BHLHE41 protein, human
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Basic Helix-Loop-Helix Transcription Factors
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Bhlhb3 protein, mouse
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Bhlhe41 protein, rat
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Carrier Proteins
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DNA-Binding Proteins
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Hes1 protein, mouse
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Hes1 protein, rat
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Homeodomain Proteins
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Immunoglobulin J Recombination Signal Sequence-Binding Protein
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Membrane Proteins
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NOTCH1 protein, human
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Neuropeptides
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Notch1 protein, mouse
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Nuclear Proteins
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RBPJ protein, human
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RNA, Messenger
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Rbpj protein, mouse
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Receptor, Notch1
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Receptors, Cell Surface
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Recombinant Proteins
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SPHKAP protein, human
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Transcription Factor HES-1
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Transcription Factors
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HES1 protein, human
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Histone Deacetylases