TORCs: transducers of regulated CREB activity.
The cAMP responsive factor CREB stimulates gene expression, following its phosphorylation at Ser133, via recruitment of the coactivator CBP. In certain cell types, CREB also functions as a constitutive activator, although the underlying mechanisms are not understood. Here, we characterize a conserved family of coactivators, designated TORCs, for Transducers of Regulated CREB activity, that enhances CRE-dependent transcription via a phosphorylation-independent interaction with the bZIP DNA binding/dimerization domain of CREB. TORC recruitment does not appear to modulate CREB DNA binding activity, but rather enhances the interaction of CREB with the TAF(II)130 component of TFIID following its recruitment to the promoter. Remarkably, in certain mucoepidermoid carcinomas, a chromosomal translocation fuses the CREB binding domain of TORC1 to the Notch coactivator Mastermind (MAML2). As expression of the TORC1-MAML2 chimera strongly induced target gene expression via CREB, our results reveal a mechanism by which CREB stimulates transcription in normal and transformed cells.
Pubmed ID: 14536081 RIS Download
Amino Acid Sequence | Animals | Cell Line | Cell Line, Transformed | Cell Line, Tumor | Cross-Linking Reagents | Cyclic AMP | Cyclic AMP Response Element-Binding Protein | Dimerization | Glutaral | Glutathione Transferase | Humans | Luciferases | Models, Biological | Molecular Sequence Data | Multigene Family | Phosphorylation | Plasmids | Polymerase Chain Reaction | Precipitin Tests | Promoter Regions, Genetic | Protein Binding | Protein Structure, Tertiary | RNA, Messenger | Recombinant Fusion Proteins | Sequence Homology, Amino Acid | Serine | Trans-Activators | Transcription Factor TFIID | Transcription, Genetic | Transfection