Divergent effects of dithiocarbamates on AP-1-containing and AP-1-less NFAT sites

Changes in the redox status of cells affect NF-kappa B and activator protei n (AP)-1 nuclear expression and activity. In particular antioxidants decrea se NF-kappa B and increase AP-I transcriptional activity, thereby regulatin g gene expression. In T cells, low concentrations of antioxidants enhance I L-2 and inhibit IL-4 expression. Since NFAT binding sites play an essential role in regulating IL-2 and IL-4 gene transcription, we studied the effect s of dithiocarbamates, using the pyrrolidine derivative of dithiocarbamate (PDTC), on the activity of the distinct AP-I-containing IL-2 NFAT and AP-I- less IL-4 NFAT enhancers elements. Consistent with the presence of AP-I pro teins within the IL-2 NFAT complex, PDTC strongly enhanced phorbol 12-myris tate 13-acetate/phytohemagglutinin-induced NFAT binding to the IL-2 NFAT en hancer and transcriptional activity of a reporter plasmid driven by this NF AT enhancer. In contrast, the activity of the IL-4 NFp enhancer, which does not bind AP-I, was abolished by PDTC treatment. In the Jurkat T cell line treated with PDTC, cc-expression of the Ca2+/calmodulin-dependent phosphata se, calcineurin, completely restored the IL-4 NFp enhancer activity. Our da ta indicate that calcineurin-mediated NFAT activity is a target for antioxi dants and provides new insights into the molecular mechanisms controlling d ifferential cytokine gene expression.