FIGURE 4.

Increased histone H3K9Ac at the promoter/enhancer regions of HLA-DRB1 and HLA-DQB1 correlates with gene expression in response to IFNγ/TNFα in THP1 cells. Left, time course of IFNγ/TNFα-induced HLA-DRB1 and HLA-DQB1 mRNA expression in THP1 cells. IL2 was included as a negative control gene, which was not induced under these conditions. THP1 cells were treated with 20 μm IFNγ and 10 μm TNFα and collected at 0 (no treatment), 4, 16, and 24 h. Total RNAs were prepared and RT-qPCRs were performed in triplicate. **, p < 0.0001 versus 0 h. Right, ChIP-qPCR data showing histone H3K9Ac enrichment levels at HLA-DRB1 and HLA-DQB1 promoter/enhancer regions in THP1 cells treated with IFNγ/TNFα. HLA-DRB1-P and HLA-DQB1-P refer to the same genomic regions where variations in acetylation were noted in the T1D patient monocytes (Fig. 3, C and D). The IL2 promoter (IL2-P) was examined as a negative control, which did not show any changes in H3K9Ac under these conditions. The ChIPs were performed as described under “Experimental Procedures.” ChIP-qPCRs were preformed in triplicates. Data shown are mean ± S.E. from triplicates. *, p < 0.002 versus 0 h; **, p < 0.0001 versus 0 h.