However, ER-α expression can be regulated through epigenetic modification, for instance methylation at the promoter [ 15], by post-translational modifications, or through direct interaction with corepressor proteins that repress ER-α-mediated transcriptional activity [ 16, 17].
Lander and Bernstein similarly determined specific histone modifications that distinguish actively expressed genes, genes poised for expression, and repressed genes in different kinds of cells.
X inactivation, the silencing of one X-chromosome in female mammals, is achieved by the establishment of multiple epigenetic modifications that result in chromatin of the inactive X (Xi) being transcriptionally repressed.
Under normal growth conditions HSF1 is repressed as an inactive monomer in part through post-translation modifications that include protein acetylation, sumoylation and phosphorylation.
PRC2 is the major methyltransferase for H3K27 methylation, a modification of histone H3 that represses gene expression programs throughout development.
In S. enterica Typhimurium, four sRNAs contribute to bacterial pathogenesis [ 30], including MgrR which regulates eptB, the modulator of LPS modification [ 36], InvR that represses ompD, encoding the outer membrane protein synthesis protein [ 37], and SgrS that controls ptsG and sopD, two genes involving in sugar uptake and regulation of secreted virulence factor [ 38].
Through the recruitment of methyl-binding proteins, this modification induces an inactive chromatin structure that represses transcription.
Our results revealed that repressed variegating hCD2 transgenes are indeed associated with known heterochromatic chromatin modifications, including H3K9me3 and DNA methylation, and positioned within or close to a repressive nuclear domain.
Another epigenetic mechanism for repressing gene transcription is the methylation of specific lysine residues in histones, a modification that is critical to shaping repressive chromatin structures [ 13, 14].
