These remodellers often act in concert with chromatin modifiers such as the polycomb group proteins which confer repressive states through modification of histone tails.
This is illustrated by modification of histone H3.
Equivalently this step resembles the action of enzymes which are involved in chemical modification of histone proteins.
Another possibility is that these additional sequences might occasionally permit spreading of de novo methylation activity by modification of histone tails.
The mechanisms by which trxG complexes modulate chromatin structure include both non-covalent, ATP-dependent nucleosome sliding and covalent modification of histone tails.
Other studies have also indicated that LPS activation of macrophages induces only low amounts of IL-10 and no significant modification of histone H3 [14], [14].
It is thought that extensive modification of histone tails determines local chromatin structure, either by influencing chromatin structure directly or by recruitment of modifying factors, such as PcG proteins.
Since histone acetylation also plays a role in regulating gene transcription, we next investigated whether modification of histone acetylation of the MHV-68 genome could induce MHV-68 to go to lytic replication from latency in S11E cells.
We specifically examined modification of histone H3 at the nucleosome 2 position of the IL-10 promoter, since this region is most strongly associated with histone phosphorylation and acetylation following stimulation through TLR4 and FcγR [14].
To better correlate chromatin condensation forms observed in these cells with functionally distinct regions of euchromatin or heterochromatin, we exploited antibodies against post-translational modification of histone H3 (K9 tri-methylated) specific for transcriptionally silenced regions of the heterochromatin [31].
The control of eukaryotic gene expression in part depends on the modification of histone proteins associated with specific genes with the acetylation and deacetylation of histones playing a critical role in gene expression [14] [16].
