Combinatorial Patterns of Histone Acetylation and Methylation in the Human Genome

Histones are characterized by numerous post-translational modifications that influence gene transcription. However, due to the lack of global distribution data in higher eukaryotic systems, it remains to be determined the extent to which gene-specific combinatorial patterns of histone modifications exist. Here we report the patterns derived from analyzing 38 histone modifications in human CD4+ T cells. Our data indicate that a large number of patterns are associated with promoters and enhancers. In particular, we identify a common modification module consisting of 17 modifications at 3,090 promoters. These modifications tend to colocalize in the genome and correlate with each other at an individual nucleosome level. Genes associated with this module tend to have higher expression levels and addition of more modifications to this module is associated with further increased expression. Our data suggest that these histone modifications may act cooperatively to prepare chromatin for transcriptional activation.