Neoplastic transformation by Notch is independent of transcriptional activation by RBP-J signalling.
Signalling through the transmembrane receptor Notch is triggered by ligand binding, which induces the proteolytic cleavage of the Notch protein. This cleavage generates an intracellular fragment of the Notch protein (Notch-IC), which translocates into the nucleus and modifies transcription of target genes through its association with the RBP-J protein. Thus, the isolated Notch-IC protein represents the constitutively activated receptor. We have performed a deletion analysis of Notch IC in order to identify the transferable transactivation domain of Notch-IC and the minimal domain of Notch-IC required for RBP-J dependent transactivational activation. Functionally, Notch-IC has been linked to cell fate decision in development and oncogenesis in vivo. In vitro, Notch-IC can cooperate in neoplastic transformation of baby rat kidney cells with the adenoviral E1A protein. We have defined the minimal domain of Notch-IC required for E1A cotransformation. This domain, consisting of the ankyrin repeats of Notch-IC only, can neither activate RBP-J dependent transcription nor does it carry a transactivation domain. Therefore, the ankyrin repeat domain of Notch-IC might trigger novel pathways relevant for transformation but unrelated to RBP-J signalling.
Dumont
E
E
Institut für Klinische Molekularbiologie und Tumorgenetik, GSF-Forschungszentrum für Umwelt und Gesundheit, München, Germany.
Fuchs
K P
KP
Bommer
G
G
Christoph
B
B
Kremmer
E
E
Kempkes
B
B
D017500:Adenovirus E1A Proteins / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002522:Chlorocebus aethiops; D003043:Cocarcinogenesis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D005786:Gene Expression Regulation; D005813:Genes, Synthetic; D006367:HeLa Cells; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051379:Mice; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D051381:Rats; D051880:Receptors, Notch; D011993:Recombinant Fusion Proteins / Q000502:physiology; D020449:Repetitive Sequences, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D015533:Transcriptional Activation
D017500:Adenovirus E1A Proteins; D004268:DNA-Binding Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins; D009687:Nuclear Proteins; C497570:RBPJ protein, human; C497571:Rbpj protein, mouse; C497572:Rbpjl2 protein, rat; D051880:Receptors, Notch; D011993:Recombinant Fusion Proteins