SHARP is a novel component of the Notch/RBP-Jkappa signalling pathway.
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.
Oswald
Franz
F
Department of Internal Medicine and Pediatrics, University of Ulm, Robert-Koch-Strasse 8, D-89081 Ulm, Germany.
Kostezka
Ulrike
U
Astrahantseff
Kathy
K
Bourteele
Soizic
S
Dillinger
Karin
K
Zechner
Ulrich
U
Ludwig
Leopold
L
Wilda
Monika
M
Hameister
Horst
H
Knöchel
Walter
W
Liptay
Susanne
S
Schmid
Roland M
RM
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009479:Neuropeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D010641:Phenotype; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000072056:Transcription Factor HES-1; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis
D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006655:Histone Deacetylases; D018398:Homeodomain Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; D012333:RNA, Messenger; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D000072056:Transcription Factor HES-1; D014157:Transcription Factors; C422085:BHLHE41 protein, human; C470968:Bhlhb3 protein, mouse; C109509:Bhlhe41 protein, rat; C489734:Hes1 protein, mouse; C489735:Hes1 protein, rat; C497761:NOTCH1 protein, human; C497762:Notch1 protein, mouse; C497570:RBPJ protein, human; C497571:Rbpj protein, mouse; C466999:SPHKAP protein, human; C078493:HES1 protein, human