Cyclic adenosine monophosphate-responsive elements are involved in the transcriptional activation of the human IL-10 gene in monocytic cells.
IL-10 plays an important role in the regulation of immune responses. We and others have demonstrated recently that cyclic adenosine monophosphate (cAMP)-elevating substances up-regulate monocytic IL-10 expression in vitro and in vivo. Computer analysis of the IL-10 promoter/enhancer region localized four putative cAMP-responsive elements (CRE1- 4) with homology to the CRE consensus motif. In electrophoretic mobility shift assays CRE1 and CRE4 bound protein complexes consisting of transcription factors CREB-1 and ATF-1, while CRE3 bound only marginal amounts of CREB-1/ATF-1 in combination with unknown protein(s). CRE2 showed no protein binding activity. In vitro mutation of CRE1 and CRE4 reduced the level of cAMP-stimulated transactivation in reporter gene assays in comparison to the wild-type promoter by 20 % and 50 %, respectively, while mutation of CRE3 had no effect. The main action of CRE4 on cAMP-dependent stimulation is probably based on its adjacent localization to the TATA box and its sequence comprising a perfect half site. Experiments with double and triple mutants and with deleted promoter fragments indicated the participation of additional elements beside the CRE motifs in the cAMP-dependent stimulation. Our data suggest that intracellular cAMP may directly affect expression of the immunoregulatory cytokine IL-10 in monocytic cells via activation of the eukaryotic transcription factors CREB-1 and ATF-1 and their binding to CRE1 and CRE4 in the upstream enhancer of the IL-10 promoter.
Platzer
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C
Institute of Anatomy Anatomy II, Medical School, Friedrich Schiller University Jena, Jena, Germany. cplatzer@mti-n.uni-jena.de
Fritsch
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E
Elsner
T
T
Lehmann
M H
MH
Volk
H D
HD
Prösch
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S
D000242:Cyclic AMP / Q000235:genetics* / Q000276:immunology; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics* / Q000276:immunology; D007948:Leukemia, Monocytic, Acute; D009000:Monocytes / Q000276:immunology / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000276:immunology; D020218:Response Elements / Q000276:immunology*; D015533:Transcriptional Activation / Q000276:immunology*; D014407:Tumor Cells, Cultured
D016753:Interleukin-10; D000242:Cyclic AMP