Distinct effects of cAMP and mitogenic signals on CREB-binding protein recruitment impart specificity to target gene activation via CREB.
Ser-133 phosphorylation of the cAMP-responsive element-binding protein (CREB) is sufficient to induce cellular gene expression in response to cAMP, but additional promoter-bound factors are required for target gene activation by CREB in response to mitogen/stress signals. To compare the relative effects of different signals on recruitment of the coactivator CREB-binding protein (CBP) to CREB in living cells, we developed a fluorescence resonance energy transfer (FRET) assay. cAMP promoted the interaction of CREB with CBP in a phosphorylation-dependent manner by FRET analysis, but mitogen/stress signals were far less effective in stimulating complex formation even though they induced comparable levels of Ser-133 phosphorylation. cAMP and non-cAMP stimuli were comparably active in promoting this interaction in the cytosol; the formation of CREB x CBP complexes in response to non-cAMP signals was specifically inhibited in the nucleus. Non-cAMP signals had no effect on intrinsic CREB- or CBP-binding activities by Far Western blot assay, thereby supporting the presence of a distinct CREB x CBP antagonist. Our studies indicate that the relative effects of cAMP and mitogen/stress signals on CREB x CBP complex formation impart selectivity to gene activation through CREB phosphorylated at Ser-133.
Mayr
B M
BM
Peptide Biology Laboratories, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037.
Canettieri
G
G
Montminy
M R
MR
D000818:Animals; D050882:CREB-Binding Protein; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008934:Mitogens / Q000378:metabolism* / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism*; D016716:PC12 Cells; D010766:Phosphorylation; D051381:Rats; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism* / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation
D017362:Cyclic AMP Response Element-Binding Protein; D008934:Mitogens; D009687:Nuclear Proteins; D015534:Trans-Activators; D012694:Serine; D000242:Cyclic AMP; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; C494365:Crebbp protein, rat; D013755:Tetradecanoylphorbol Acetate