Chromatin remodeling of the Th2 cytokine gene loci

Differentiation of naive CD4 T cells into Th2 cells is accompanied by chromatin remodeling including hyperacetylation of histones H3 and H4 in the nucleosomes associated with the IL-4, IL-13 and IL-5 genes. A conserved GATA3 response element (CGRE) containing four GATA consensus sequences was identified 1.6 kbp upstream of the IL-13 gene, corresponding with the 5′ border of the Th2-specific histone hyperacetylation region. The CGRE was shown to bind to GATA3, histone acetyl transferase complexes including CBP/p300, and RNA polymerase II. As for the IL-5 gene locus, CD28 costimulation selectively enhanced histone hyperacetylation through NF-κB activation and subsequent upregulation of GATA3. Chromatin remodeling of type 2 cytokine gene loci occurs also in developing Tc2 cells. IL-4 production and histone hyperacetylation in IL-4-associated nucleosomes in developing Tc2 cells were significantly lower than those of Th2 cells; however, cytokine production and histone hyperacetylation of IL-5 and IL-13 genes were equivalent. Developing Tc2 cells expressed lower GATA3 levels and dramatically increased levels of repressor of GATA (ROG). A ROG response element in the IL-13 gene exon 4 displayed Tc2-specific binding of ROG, HDAC1 and HDAC2. Thus, ROG may confer CD8 T cell-specific repression of histone hyperacetylation and activation of the IL-4 gene locus.