Histone deacetylases (HDACs), also known as lysine deacetylases (KDACs), are a class of enzymes that remove acetyl groups from core histones (H2A, H2B, H3 and H4), thereby regulating gene expression.
These epigenetic enzymes influence the structure of chromatin, the protein-DNA complex that forms into chromosomes residing in the nucleus. By removing an acetyl group, HDACs enable the tightening of the chromatin structure into what is called heterochromatin. Specifically, the DNA that wraps around the histones is more compact, which can reduce the transcription of important genes.
In contrast, histone acetyltransferases (HATs) add acetyl groups to histones and are associated with euchromatin, a loosened chromatin structure that increases transcription and gene expression. HDACs are also tightly involved in cell cycle regulation, cell proliferation, and in the development of human cancer. By studying the activity and inhibition of HDACs, researchers can gain a better understanding of the impact histone deacetylation has on diseases and various cellular processes.