Independence of repressive histone marks and chromatin compaction during senescent heterochromatic layer formation.

ABSTRACT: The expansion of repressive epigenetic marks has been implicated in heterochromatin formation during embryonic development, but the general applicability of this mechanism is unclear. Here we show that nuclear rearrangement of repressive histone marks H3K9me3 and H3K27me3 into nonoverlapping structural layers characterizes senescence-associated heterochromatic foci (SAHF) formation in human fibroblasts. However, the global landscape of these repressive marks remains unchanged upon SAHF formation, suggesting that in somatic cells, heterochromatin can be formed through the spatial repositioning of pre-existing repressively marked histones. This model is reinforced by the correlation of presenescent replication timing with both the subsequent layered structure of SAHFs and the global landscap

SUBMITTER: Chandra T 

PROVIDER: S-EPMC3701408 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature