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 protein (AP)-1 nuclear expression and activity. In particular antioxidants decrease NF-kappa B and increase AP-I transcriptional activity, thereby regulating gene expression. In T cells, low concentrations of antioxidants enhance IL-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 effects 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 proteins within the IL-2 NFAT complex, PDTC strongly enhanced phorbol 12-myristate 13-acetate/phytohemagglutinin-induced NFAT binding to the IL-2 NFAT enhancer and transcriptional activity of a reporter plasmid driven by this NFAT 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 phosphatase, calcineurin, completely restored the IL-4 NFp enhancer activity. Our data indicate that calcineurin-mediated NFAT activity is a target for antioxidants and provides new insights into the molecular mechanisms controlling differential cytokine gene expression. [References: 32]

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