CHARACTERIZATION OF THE CONSTITUTIVE AND INDUCIBLE COMPONENTS OF A T-CELL IL-4 ACTIVATION RESPONSIVE ELEMENT

An IL-4 regulatory element, activation responsive element (ARE), locat ed between -88 and -60, contributes to activation-dependent transcript ion of IL-4/CAT reporter gene constructs in T cells. It was previously demonstrated that nuclear proteins present in both unstimulated and s timulated T cells specifically interact with the ARE. In this study, t hese proteins were further characterized. UV cross-linking experiments established that multiple proteins are associated with the ARE in bot h the constitutive and activation-dependent complexes and several of t hese have identical apparent m.w. The formation of both complexes is d ependent on the same ARE subsequence. In addition, activator protein 1 family members are uniquely associated with the activation-dependent complex. These results support a model in which activation-dependent p roteins, including jun/fos family members, associate with a preexistin g transcription complex to influence inducible IL-4 gene transcription . The ARE shares 9 bp of sequence identity with the IL-2 nuclear facto r of activated T cell (NF-AT) binding site within the critical protein binding region, and several features of ARE-protein interactions are similar to the NF-AT transcription complex. However, we demonstrate th at the constitutive nuclear ARE-associated factors react with Abs, rai sed to NF-AT(p) and NF-AT(c), preferentially bind to the ARE but not t o the NF-AT binding site and are cyclosporin A sensitive. Taken togeth er, these data indicate that there are IL-4 gene-specific factors asso ciated with the ARE and that the formation of the ARE and NF-AT comple xes are regulated differently.