Genome-wide maps of chromatin state in HSC, Pro B and mature B cells

We have used a genome-wide ChIP-sequencing approach to define and investigate the dynamics of the cis-regulatory landscape in three developmental stages of the murine hematopoietic system. To this end, we have compared the profiles of H3K4me3, H3K4me1, H3K27ac, H3K27me3 and H3K9me2 in HSCs, committed pro-B and splenic mature B cells. We find the enhancer repertoire to be dynamically reshaped during hematopoiesis progression, surprisingly only a small fraction of primed enhancers in HSCs or committed progenitors become activated in subsequent stages. In turn, the majority of active enhancers in terminally differentiated cells are not primed in earlier stages. We also found that The heterochromatin mark H3K9me2 covers large domains that remain largerly invariant across the three stages and are depleted in both active chromatin marks and the Polycomb related mark H3K27me3.