Methylation is added to the lysine or arginine residues of histones H3 and H4, with different impacts on transcription. Low levels of global acetylation are also found throughout transcribed genes, whose function remains unclear. For example, acetylation of K9 and K27 on histone H3 (H3K9ac and H3K27ac) is usually associated with enhancers and promoters of active genes. Histone acetylation is largely targeted to promoter regions, known as promoter-localized acetylation. An imbalance in the equilibrium of histone acetylation is associated with tumorigenesis and cancer progression.Īcetyl groups are added to lysine residues of histones H3 and H4 by histone acetyltransferases (HAT) and removed by deacetylases (HDAC). Histone acetylation is involved in cell cycle regulation, cell proliferation, and apoptosis and may play a vital role in regulating many other cellular processes, including cellular differentiation, DNA replication and repair, nuclear import and neuronal repression. The charge neutralization results in a weaker histone: DNA interaction, allows transcription factor binding and significantly increases gene expression (Roth et al., 2001). Unmodified lysine residues are positively charged but acetylation results in neutralization of the charge on histones, which reduces the interaction of histones and negatively charged DNA.

Examining histone modifications at a particular region, or across the genome, can reveal gene activation states, locations of promoters, enhancers, and other gene regulatory elements.Īcetylation is one of the most widely studied histone modifications since it was one of the first discovered to influence transcriptional regulation.

Together, these histone modifications make up what is known as the histone code, which dictates the transcriptional state of the local genomic region. To find out more see our full histone modifications poster Figure 1: The most common histone modifications.

Istone pdf creator download