Question

What are the main epigenetic mechanisms that interfere with the expression of genes?

CRCs (chromatin remodeling complexes) drive the formation of heterochromatin regardless of any regulatory input.

CRCs condense chromatin in centromeres, telomeres and origins of replication. gene-rich genomic DNA regions that are not condensed by CRCs (chromatin remodeling complexes) are able to be accessed by transcription factors that may activate or repress transcription (gene expression).

CRCs (chromatin remodeling complexes) locally (regionally) reorganize global chromatin structure making it inaccessible (by condensing) or accessible (by relaxing) to transcription factors.

CRCs (chromatin remodeling complexes) recognize certain labels, chemical modifications on specific amino acids side chains on histone tail domains and as a response promote the condensation or relaxation of chromatin regions preventing or allowing transcription to occur, respectively.

Answer 1

As we know that epigenetic changes are due to binding of certain chemical groups to the amino acids which protruding in the histones, where tail of amino acids binds with acetyl-, methyl-, or other groups. Condensation (non accessible) and condensation (accessible) process is performed by HDAC and HAT and changes in these amino acids (lysine, arginine or other) can alter the gene expression (DNA). Therefore, last statement is the relevant statement “CRCs (chromatin remodeling complexes) recognize certain labels, chemical modifications on specific amino acids side chains on histone tail domains and as a response promote the condensation or relaxation of chromatin regions preventing or allowing transcription to occur, respectively.