histone deacetylase complex

Definition

Target type: cellularcomponent

A protein complex that possesses histone deacetylase activity. [GOC:mah]

Histone deacetylase complexes (HDACs) are multi-protein assemblies that play a critical role in gene regulation by removing acetyl groups from lysine residues on histone tails. These complexes are found in the nucleus and are associated with chromatin, the complex of DNA and proteins that makes up chromosomes. The specific composition of an HDAC complex can vary, but generally includes the following components:

1. **HDAC enzyme:** This is the catalytic subunit that removes acetyl groups from histones. There are 18 known HDACs in humans, which can be categorized into four classes: Class I (HDAC1, HDAC2, HDAC3, HDAC8), Class IIa (HDAC4, HDAC5, HDAC7, HDAC9), Class IIb (HDAC6, HDAC10), and Class IV (HDAC11).
2. **Scaffold proteins:** These proteins act as a bridge between the HDAC enzyme and other components of the complex, helping to bring them together and stabilize the complex. Some common scaffold proteins include Sin3A, NCoR, and SMRT.
3. **Co-repressors:** These proteins enhance the activity of the HDAC enzyme and help to recruit the complex to specific DNA sequences. Co-repressors can include proteins like mSin3A, NCoR, SMRT, and RbAp48/46.
4. **DNA-binding proteins:** These proteins recognize specific DNA sequences and target the HDAC complex to particular genes. Examples include the transcription factors YY1 and Sp1.

The specific composition of an HDAC complex can vary depending on the cell type, developmental stage, and the gene being regulated. This variation contributes to the diversity of HDAC complex function and their roles in a wide range of cellular processes, including cell growth, differentiation, and apoptosis.

The HDAC complex plays a crucial role in gene regulation by altering the accessibility of DNA to transcription factors. By removing acetyl groups from histone tails, the HDAC complex promotes a more compact chromatin structure, making it more difficult for transcription factors to bind to the DNA and initiate gene expression. This process of histone deacetylation is often associated with gene silencing.

The activity of HDAC complexes is tightly regulated by a variety of mechanisms, including post-translational modifications, protein-protein interactions, and changes in cellular localization. Dysregulation of HDAC activity is implicated in a number of diseases, including cancer, neurodegenerative disorders, and cardiovascular diseases. Consequently, HDACs have become attractive targets for drug development, with a number of HDAC inhibitors currently in clinical trials.'
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Proteins (18)

Compounds (132)