title: Coordinate transactivation of the interleukin-2 CD28 response element by c-Rel and ATF-1/CREB2.
abstract: The interleukin-2 CD28 response element (CD28RE) acts as a composite enhancer, in conjunction with a 3'-12-O-tetradecanoylphorbol-13-acetate response element (TRE)-like element, to confer CD28 receptor-dependent inducibility to the interleukin-2 promoter in T-cells. When inserted as a single copy upstream of a basal promoter, this composite enhancer, termed the CD28RE-TRE, is both highly active and CD28-inducible in transactivation assays. A multicomponent nuclear protein complex that binds the CD28RE-TRE was isolated by DNA affinity chromatography from nuclear extracts of mitogen- and CD28 receptor-costimulated human T-cells. Immunological and biochemical analyses of this complex reveal the presence of c-Rel, ATF-1, and CREB2 as major DNA-binding components. Coexpression of c-Rel in combination with ATF-1, CREB2, or ATF-1/CREB2 leads to synergistic transactivation of a CD28RE-TRE reporter plasmid in quiescent Jurkat T-cells. Furthermore, CD28-dependent transactivation of the CD28RE-TRE is specifically inhibited by cAMP response element-binding protein (CREB) dominant-negative expression vectors. Moreover, mutant promoter constructs in which the internal 5'-CD28RE and 3'-TRE-like sequences have been topologically positioned 180 degrees out of phase with one another show loss of mitogen- and CD28-dependent inducibility. Finally, the addition of the CREB-binding transcriptional coactivator p300 leads to a dramatic CREB-dependent increase in both mitogen- and CD28-mediated transactivation of the CD28RE-TRE. These findings demonstrate that full physiological responsiveness to CD28 receptor stimulation in T-cells is dependent on topologically linked sequences within the CD28RE-TRE composite enhancer and provide strong support of a direct role for the CREB family of transcription factors and p300/CREB-binding protein coactivator proteins in cytokine gene induction during T-cell activation.
authors.affiliation: Laboratory of Pathology, NCI, National Institutes of Health, Bethesda, Maryland 20892-1500, USA.
authors.forename: W G
authors.initials: WG
authors.lastname: Butscher
authors.forename: C
authors.initials: C
authors.lastname: Powers
authors.forename: M
authors.initials: M
authors.lastname: Olive
authors.forename: C
authors.initials: C
authors.lastname: Vinson
authors.forename: K
authors.initials: K
authors.lastname: Gardner
mesh_terms: D051697:Activating Transcription Factor 1; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D018106:CD28 Antigens / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D002846:Chromatography, Affinity; D004247:DNA; D004268:DNA-Binding Proteins; D005822:Genetic Vectors; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D019169:Jurkat Cells; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020569:Proto-Oncogene Proteins c-rel; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: D051697:Activating Transcription Factor 1; D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D014157:Transcription Factors; D015759:Ionomycin; D004247:DNA; D013755:Tetradecanoylphorbol Acetate