Class I and Class IIa histone deacetylases (HDACs) (Class I/IIa HDACs)

Class I and Class IIa histone deacetylases (HDACs) are a group of enzymes that regulate gene expression by removing acetyl groups from lysine residues on histones and other proteins [PMID: 22449941]. Class I HDACs, including HDAC1, 2, 3, and 8, are primarily nuclear and are essential for cell cycle progression and survival [UniProt: P62875]. Class IIa HDACs, including HDAC4, 5, 7, and 9, shuttle between the nucleus and cytoplasm and play specialized roles in tissue development and cellular differentiation [UniProt: P56524]. These enzymes are frequently dysregulated in various cancers, where they contribute to the silencing of tumor suppressor genes and promote uncontrolled proliferation [PMID: 30107153]. In addition to oncology, Class I/IIa HDACs are implicated in neurodegenerative diseases and inflammatory conditions due to their role in protein stability and immune signaling [PMID: 21346764]. Pharmacological inhibitors of these HDACs, such as vorinostat and romidepsin, work by binding to the zinc-containing catalytic site, leading to hyperacetylation of target proteins [PubChem: CID 60198]. This hyperacetylation results in the reactivation of silenced genes, induction of cell cycle arrest, and the promotion of apoptosis in malignant cells [StatPearls: NBK559020]. Clinical use of these inhibitors has shown efficacy in treating hematological malignancies like cutaneous T-cell lymphoma and multiple myeloma [PMID: 28410215]. However, therapeutic challenges remain, including off-target toxicities such as thrombocytopenia and the need for more selective inhibitors to improve the safety profile [PMID: 17440030].

Other names

HDAC Class IHDAC Class IIaZinc-dependent histone deacetylasesClassical HDACs

Competitive inhibition of the zinc-dependent catalytic site of Class I and Class IIa histone deacetylases, which prevents the removal of acetyl groups from lysine residues on histones and non-histone proteins [PubChem: CID 60198, StatPearls: NBK559020]. This leads to hyperacetylation, resulting in the transcriptional reactivation of genes involved in cell cycle arrest and apoptosis [PMID: 22449941].