Histone modifications and gene expression levels on the euchromatic vs. heterochromatic side of the CTRs in <i>Drosophila</i> S2 cell line.

<p>(A) Enrichment levels of active (solid lines) and repressive (dashed lines) histone modifications around the H3K27me3 CTRs identified in S2 cells. Negative and positive distances indicate euchromatic and heterochromatic sides of the identified CTRs, respectively. (B) Expression levels of genes on the euchromatic or heterochromatic side of CTRs. Barplots represent Mean±SE for all genes (grey), genes within the 4 kb region on the euchromatic side (yellow) or the heterochromatic side (green) of CTRs. The expression levels for genes on euchromatic side of CTRs are significantly greater than those of the genes on the heterochromatic side (p<2.2E-16, Wilcoxon rank sum test). (C) An example of 7 CTRs (red bars) predicted by CTRICS. Bar height reflects T-score, top and bottom rows denotes the orientation of the CTRs. The panel below CTR shows H3K27me3 domains called by SICER. RNA-Seq signal, RNA Pol II binding, as well as active histone modification (H3K4me3) are depleted in heterochromatic regions which have high H3K27me3, while they are enriched in euchromatic regions.