The cyclic adenosine 5' monophosphate response element modulator supresses IL-2 production in stimulated T cells by a chromatin-dependent mechanism

Tenbrock K, Juang YT, Tolnay M and Tsokos GC
Source: J Immunol
Publication Date: (2003)
Issue: 170: 2971-2976
Research Area:
Immunotherapy / Hematology
Cells used in publication:
T cell, human peripheral blood unstim.
Species: human
Tissue Origin: blood
Interleukin-2 (IL-2) is produced by T cells upon engangement of the TCR/CD3 complex. The production of IL-2 is tightly controlled by several transcriptional factors such as CREM (cAMP response element modulator) that binds to the IL-2 promoter. The authors studied the transcriptional function of CREM on IL-2 production. Therefore, primary human T cells were nucleofected with a plasmid encoding CREM antisense. The function of CREM was revealed via different assays. CREM antisense was found to decrease the binding of CREM protein to the IL-2 promoters and to up-regulate IL-2 mRNA and protein. It also increased the DNA accessibility on the IL-2 promoter and the binding of acetylated histones.
The production of IL-2 is tightly controlled by several transcription factors that bind to the IL-2 promoter. The cAMP response element modulator (CREM) is known to form complexes with CREB and bind to the -180 site of the IL-2 promoter in anergic and in systemic lupus erythematosus T cells. In this study we show that CREM is transcriptionally induced in T cells following stimulation through CD3 and CD28, binds to the IL-2 promoter in vivo, and suppresses IL-2 production. Transfection of an antisense CREM plasmid into T cells blocked the expression and binding of CREM to the IL-2 promoter and the decrease of IL-2 production, which follows the early increase after T cell stimulation with CD3 and CD28. In addition, as assessed by chromatin immunoprecipitation experiments, antisense CREM prevented the binding of protein 300 and cAMP response element binding protein and promoted the acetylation of histones. Antisense CREM also enhanced the accessibility of the IL-2 promoter to endonucleases and prevented the condensation of chromatin in vivo. Our data suggest that upon T cell activation, CREM gradually replaces phosphorylated CREB at the -180 site of the IL-2 promoter. CREM, in turn, binds protein 300 and cAMP response element binding protein, but CREM is unable to activate its histone acetyltransferase activity, which results in condensation of chromatin and down-regulation of IL-2 production.