Histone deacetylase class I and IIa (HDAC class I and IIa)

Histone deacetylase class I and IIa encompass a family of enzymes responsible for deacetylating lysine residues on histone and non-histone proteins, thereby playing a central role in epigenetic regulation of gene expression and chromatin structure[2][4][6]. **Class I HDACs** (HDAC1, HDAC2, HDAC3, HDAC8) are primarily nuclear, zinc-dependent, and highly active, whereas **Class IIa HDACs** (HDAC4, HDAC5, HDAC7, HDAC9) alternate between the nucleus and cytoplasm and possess very low intrinsic deacetylase activity due to a critical amino acid substitution in the catalytic site[1][4]. Instead, class IIa HDACs often function as scaffolds, recruiting class I HDACs or other corepressors to mediate transcriptional repression. Together, these classes modulate fundamental cellular processes including differentiation, proliferation, apoptosis, and metabolism, and are implicated in diverse diseases, particularly cancer, metabolic syndrome, and neurological disorders[2][3]. Consequently, they represent important therapeutic targets, with multiple inhibitors approved or in clinical development[5].

Other names

HDACs class I and IIaHistone deacetylase 1/2/3/8 (class I components)Histone deacetylase 4/5/7/9 (class IIa components)HDAC1, HDAC2, HDAC3, HDAC8, HDAC4, HDAC5, HDAC7, HDAC9

Inhibition of histone/protein deacetylation Alteration of chromatin structure leading to increased gene expression Modulation of transcription factor activity via acetylation Induction of apoptosis in cancer cells Modulation of non-histone protein function via acetylation status