CAMP AND TUMOR-NECROSIS-FACTOR COMPETITIVELY REGULATE TRANSCRIPTIONALACTIVATION THROUGH AND NUCLEAR FACTOR-BINDING TO THE CAMP-RESPONSIVE ELEMENT ACTIVATING TRANSCRIPTION FACTOR ELEMENT OF THE ENDOTHELIAL-LEUKOCYTE ADHESION MOLECULE-1 (E-SELECTIN) PROMOTER

The cAMP-responsive element/activating transcription factor (CRE/ATF) element (also known as NF-ELAM1) of the endothelial leukocyte adhesion molecule-1 (ELAM-1) promoter is necessary for full cytokine responsiv eness. It differs from a consensus cAMP-responsive element (CRE) by 1 nucleotide (G --> A conversion) and does not mediate transcriptional a ctivation in response to cAMP. We reported previously that cAMP actual ly decreases ELAM-1 synthesis induced by tumor necrosis factor (TNF). We now show that cAMP decreases the ELAM-1 promoter response to TNF in transient transfection assays in bovine aortic endothelial cells and that cAMP-mediated inhibition maps to the CRE/ATF element. Electrophor etic mobility shift assays using the ELAM-1 CRE/ATF DNA sequence revea l three complexes. Antibody supershift assays suggest the slowest migr ating form (complex 1) contains ATF2, the middle form (complex 2) cont ains ATF2 and c-Jun, and the fastest migrating form (complex 3) contai ns a CRE-binding protein. TNF increases c-Jun-containing complex 2 whi le diminishing complex 1, whereas cAMP decreases complex 2 and increas es complex 1. Complex 3 is unchanged by either treatment, and the CRE- binding protein is not phosphorylated, Our data suggest that a change in the composition of the proteins binding to the CRE/ATF promoter ele ment contributes to the competing effects of TNF and cAMP on ELAM-1 ge ne expression.