Figure 2.

5hmC distribution on genomic elements and histone modifications. The percentage of 5hmC was normalized to the length (bp) of each genomic segment considered. (A) 5hmC was enriched on promoters (± 1 kb) in embryonic stem cells (ESCs) (*P < 0.01).(B) 5hmC was enriched on exons with respect to introns (*P < 0.01).(C) 5hmC was significantly enriched in active enhancers in ESCs and in poised enhancers in differentiated tissues (*P < 0.01; **P < 0.05).(D) Promoters with low and intermediate presence of CpG islands (LCP and ICP, respectively) were preferentially marked by DNA hydroxymethylation with respect to promoters with high CpG (HCP) (*P < 0.01). (E) In ESCs, promoters with both H3K4me3 and H3K27me3 (K4/K27) and promoters with H3K27me3 but not H3K4me3 (K27) were significantly enriched in DNA hydroxymethylation compared with promoters with H3K4me3 but not H3K27me3 (K4) (*P < 0.01). (F) Analysis of correlations between 5hmC and histone modifications in all four cell types (*P < 0.01).