Novel CD28-Responsive Enhancer Activated by CREB/ATF and AP-1 Families in the Human Interleukin-2 Receptor α-Chain Locus

Abstract

The interaction of interleukin-2 (IL-2) with its receptor (IL-2R) critically regulates the T-cell immune response, and the α chain CD25/IL-2Rα is required for the formation of the high-affinity receptor. Tissue-specific, inducible expression of the IL-2Rα gene is regulated by at least three positive regulatory regions (PRRI, PRRII, and PRRIII), but none responded to CD28 engagement in gene reporter assays although CD28 costimulation strongly amplifies IL-2Rα gene transcription. By DNase I hypersensitivity analysis, we have identified a novel TCR-CD3- and CD28-responsive enhancer (CD28rE) located 8.5 kb 5′ of the IL-2Rα gene. PRRIV/CD28rE contains a functional CRE/TRE element required for CD28 signaling. The T-cell-specific, CD28-responsive expression of the IL-2Rα gene appears controlled through PRRIV/CD28rE by cooperation of CREB/ATF and AP-1 family transcription factors.

ACKNOWLEDGMENTS

We thank V. Coulon for pcDNA3-c-Jun, pcDNA-Jun B, and pcDNA-Jun D; J.-M. Blanchard for pCMV-ATF-1; P. Quinn for pcDNA3-CREB and the CREB dominant negative form, pcDNA3-CREB (S133A); A. Moretta for anti-CD28 248 and anti-CD3 289; and R. Schwinzer for anti-CD28 BW828 (IgG2a). We also thank P. A. Baeuerle, Y. Collette, B. Kahn-Perlès, M.-Z. Lai, P. Rameil, and P. Sassone-Corsi for helpful suggestions.

This work was supported by the Institut National de la Santé et de la Recherche Médicale and by grants from Association pour la Recherche sur le Cancer and Comité des Bouches-du-Rhône de la Ligue Nationale Contre le Cancer. J.-H. Yeh was supported by a fellowship from the French government (BGF).