Histone deacetylase class II enzyme (HDAC class II)

Histone deacetylase class II enzymes are a subgroup within the larger family of zinc-dependent histone deacetylases that catalyze the removal of acetyl groups from lysine residues on both histones and non-histone proteins. This enzymatic activity results in chromatin condensation and transcriptional repression. Class II HDACs share homology with yeast HDA1 and are further divided into two subclasses: class IIa (HDAC4, 5, 7, 9), which possess unique adapter domains allowing regulated subcellular localization via phosphorylation-dependent binding to 14‑3‑3 proteins; and class IIb (primarily HDAC6), which has distinct structural modules enabling specialized functions such as cytoskeletal regulation. These enzymes play critical roles in regulating gene expression during development, cell cycle progression, differentiation processes, neuronal function, cardiac biology—and their dysregulation is implicated in cancer progression as well as other diseases. They interact with various transcription factors/corepressors including MEF2 family members.[2][3][5] Drugs that inhibit these enzymes (“HDAC inhibitors”) have shown promise especially in oncology by reversing aberrant epigenetic silencing but present challenges related to selectivity and safety.[2][5]

Other names

Class II histone deacetylaseHDAC4, HDAC5, HDAC6, HDAC7, HDAC9 (individual isoforms)Class IIa histone deacetylase (HDAC4, 5, 7, 9)Class IIb histone deacetylase (HDAC6)

Drugs targeting this molecule typically act as histone deacetylase inhibitors, blocking the removal of acetyl groups from lysine residues on histones and other proteins. This leads to increased acetylation levels, resulting in a more open chromatin structure and altered gene expression—often reactivating tumor suppressor genes or modulating cell differentiation/apoptosis pathways.[2][3]