An intron GATA-binding site regulates chromatin accessibility and is essential for IL-4 gene expression in mast cells

Several GATA-binding sites have been identified in regions both distal to and within the murine IL-4 gene locus, yet their relative role in IL-4 expression is unknown. Chromatin immunoprecipitation assays were used to demonstrate that GATA-1 and GATA-2 are associated with a regulatory element within the second intron of the IL-4 gene in murine mast cells in vivo. Furthermore, although expression from a stably integrated wild-type IL-4 minigene parallels endogenous IL-4 gene expression, mutation of the GATA-binding element, but not an SP-1-binding site, virtually abolishes transcription in mast cells, an observation that correlates with the local loss of H3 and H4 histone acetylation in the intron. Treatment with the chromatin remodeling agents 5 azacytidine and trichostatin A can restore this defect in transcription. These results define an essential site of GATA influence on IL-4 expression in mast cells and directly support the idea that GATA factors have a profound impact on locus accessibility.