FIG. 6.

Histone acetylation is not directly related to histone loss at the IL-2 gene promoter. (A) Time course of histone acetylation during the first 30 min of P/I activation of EL-4 T cells. Cells were stimulated with P/I for 5, 10, 20, and 30 min, and ChIP assays were performed with antibodies against acetylated H4 (solid lines) and acetylated H3K9 (stippled lines). Immunoprecipitated DNA was amplified with IL-2 primer sets B (grey) and F (black). The data are presented as the ratios of immunoprecipitated DNA to total input DNA and normalized to the value for the unstimulated cell sample, which was set at 1. The data presented are the combined means ± standard errors (error bars) of replicate PCR values from three independent repeats. (B) Schematic showing the time frame of treatment of cells with TsA followed by activation with P/I and the times of harvesting for ChIP assays. (C) Histone hyperacetylation does not promote histone loss at the IL-2 promoter. EL-4 cells were treated with TsA for 5 h and then not stimulated (NS) or stimulated with P/I for 30 min, 2 h, or 4 h. Cells were also activated without prior treatment with TsA (control [Ctl]). ChIP assays were performed with antibodies against acetylated H3 (AcH3) and the C terminus of H3 (H3-C), and the immunoprecipitated DNA was amplified with IL-2 primer sets B and F. Data are plotted as ratios of immunoprecipitated sample to total input sample. The increase (fold) in acetylation levels after TsA treatment and the fold decrease (fold) in total H3 after activation are also shown on or below the graph.