Effects of mutation of the CREB binding site of the somatostatin promoter on cyclic AMP responsiveness in CV-1 cells.

The transcription factors CREB (cAMP response element binding protein) and ATF (activating transcription factor) recognize DNA containing the consensus sequence TGACGTCA. We compared the neuropeptide somatostatin promoter, which binds CREB and is activated by cAMP, to the adenovirus E2A promoter, which binds ATF but is not activated by cAMP, to determine which specific nucleotides within a CREB/ATF recognition sequence confer cAMP responsiveness. Several mutant somatostatin promoters were generated containing part of all of the E2A ATF binding site. Some of the hybrid CREB/ATF binding sites competed for factor binding to a wild-type somatostatin promoter probe. However, only the wild-type CREB binding site promoter could confer cAMP activation on a linked CAT plasmid. Furthermore, this wild-type CREB binding site could confer cAMP activation on the CAT plasmid only if it was adjacent to a wild-type somatostatin TATA box and cap site. These results suggest that slight deviation from a wild-type CREB recognition sequence might be tolerated by factor(s) binding to cAMP response element-like sequences. However, transcription activation may require a particular CREB recognition sequence, as well as additional promoter elements that bind proteins that interact with CREB.