Histone deacetylase (Class I, II, and IV) (HDAC (Class I/II/IV))

Histone deacetylases (HDACs) are a family of zinc-dependent enzymes that catalyze the removal of acetyl groups from lysine residues on histone and non-histone proteins, leading to chromatin condensation and transcriptional repression[1][5]. HDACs are divided into four classes based on similarity to yeast orthologs: class I (HDAC1, HDAC2, HDAC3, HDAC8), class II (further divided to IIa and IIb), and class IV (HDAC11)[3]. The term "Class I/II/IV HDACs" collectively refers to all zinc-dependent histone deacetylase family members except class III (sirtuins), which are NAD-dependent and structurally distinct[3][5]. These enzymes play central roles in epigenetic regulation, affecting gene expression, cellular differentiation, development, survival, and disease states such as cancer, neurological disorders, and inflammation[1][4][5]. Pharmacological inhibition of HDACs by drugs such as vorinostat, romidepsin, belinostat, and panobinostat is an established therapeutic strategy in oncology, though toxicity and lack of isoform-selectivity remain clinical challenges[1]. Biomarkers for HDAC activity include acetyl-histone levels, while ongoing research seeks safer, more selective inhibitors due to the broad and context-dependent effects of HDAC blockade.

Other names

Histone deacetylasesHDACsHDAC1HDAC2HDAC3HDAC8 (Class I)HDAC4HDAC5HDAC6HDAC7HDAC9HDAC10 (Class II)HDAC11 (Class IV)

Inhibition of deacetylase activity resulting in increased histone acetylation and gene expression - Non-selective or class/isoform-selective inhibition, depending on drug[1][2]