Epigenetics: Chromatin Organization and Function

Epigenetics refer to processes such as histone post-translational modifications (PTMs), DNA methylation and RNA that regulate gene activity and expression but are not dependent on alterations in DNA sequence. Herein, we review histone PTMs, histone variants and DNA modifications in the functioning of the nucleosome as an epigenetic signalling module. The majority of the human genome is transcribed, with most of the genome producing non-coding RNA, some of which is a component of the nuclear matrix, a dynamic RNA protein nuclear sub-structure. Non-coding RNA and coding RNA are associated with epigenetic modifiers, architectural chromatin proteins, coactivators and corepressors. The impact of changes in DNA sequence (single nucleotide polymorphisms) on the epigenome is discussed.