HDAC2 Protein — Histone Deacetylase 2

HDAC2 Protein — Histone Deacetylase 2

Overview

Hdac2 Protein — Histone Deacetylase 2 plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Histone Deacetylase 2 (HDAC2) is a Class I histone deacetylase that plays a critical role in epigenetic regulation, synaptic plasticity, and cognitive function. As part of the [HDAC](/entities/hdac-enzymes) family, HDAC2 catalyzes the removal of acetyl groups from histone lysine residues, leading to chromatin condensation and transcriptional repression. In the brain, HDAC2 is particularly important for regulating genes involved in memory formation, synaptic plasticity, and neuronal survival. Dysregulation of HDAC2 has been implicated in Alzheimer's disease, depression, and various other neurological disorders, making it an important therapeutic target. [@hdaca]

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HDAC2 Protein — Histone Deacetylase 2

Overview

Hdac2 Protein — Histone Deacetylase 2 plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Histone Deacetylase 2 (HDAC2) is a Class I histone deacetylase that plays a critical role in epigenetic regulation, synaptic plasticity, and cognitive function. As part of the [HDAC](/entities/hdac-enzymes) family, HDAC2 catalyzes the removal of acetyl groups from histone lysine residues, leading to chromatin condensation and transcriptional repression. In the brain, HDAC2 is particularly important for regulating genes involved in memory formation, synaptic plasticity, and neuronal survival. Dysregulation of HDAC2 has been implicated in Alzheimer's disease, depression, and various other neurological disorders, making it an important therapeutic target. [@hdaca]

<div class="infobox infobox-protein"> [@hdacb]
<table> [@hdacc]
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Histone Deacetylase 2</th></tr> [@hdacd]
<tr><td><strong>Protein Name</strong></td><td>Histone Deacetylase 2</td></tr> [@selective]
<tr><td><strong>Gene Name</strong></td><td>HDAC2</td></tr> [@hdace]
<tr><td><strong>UniProt ID</strong></td><td>[Q92769](https://www.uniprot.org/uniprot/Q92769)</td></tr> [@hdacf]
<tr><td><strong>Molecular Weight</strong></td><td>55 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Nucleus</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Class I Histone Deacetylases</td></tr>
<tr><td><strong>PDB Structures</strong></td><td>4LXZ, 5YJR, 6XU1, 6WON</td></tr>
<tr><td><strong>Chromosomal Location</strong></td><td>6q21</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/anxiety" style="color:#ef9a9a">Anxiety</a>, <a href="/wiki/autism" style="color:#ef9a9a">Autism</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">177 edges</a></td>
</tr>
</table>
</div>

Structure and Catalytic Mechanism

Domain Architecture

HDAC2 contains several functional domains:

Catalytic Core Domain: The active site contains a zinc-binding motif (Asp-His-Asp-His) that coordinates Zn²⁺ for catalysis

N-terminal Region: Contains protein-protein interaction motifs for forming multi-protein complexes

C-terminal Tail: Involved in regulation and post-translational modifications

Catalytic Mechanism

HDAC2 catalyzes the hydrolysis of acetyl-lysine residues through a two-step mechanism:

Substrate binding: Acetyl-lysine enters the active site pocket

Zinc-mediated hydrolysis: The coordinated Zn²⁺ polarizes the carbonyl group, enabling nucleophilic attack by a water molecule

Product release: Lysine is released with the acetyl group removed

The active site pocket is highly conserved among Class I HDACs and is the target of HDAC inhibitors.

HDAC2 Complexes

HDAC2 functions primarily as part of multi-protein transcriptional repressor complexes:

Sin3 Complex

• Sin3A: Scaffold protein
• HDAC1/HDAC2: Catalytic subunits
• RBBP4/7: Histone-binding proteins
• Methyl-DNA binding proteins: Sequence-specific recruitment

CoREST Complex

• CoREST1/2: Scaffolding proteins
• HDAC1/HDAC2: Catalytic function
• REST: Transcription factor for neuronal genes

NuRD Complex

• Mi-2α/β (CHD4): ATP-dependent chromatin remodeler
• MTA1/2: Metastasis-associated proteins
• HDAC1/HDAC2: Catalytic subunits
• RbAp46/48: Histone-binding proteins

REST/CoREST Complex

• REST: RE1 Silencing Transcription Factor
• CoREST: Co-repressor
• HDAC1/HDAC2: Mediates repression

Expression and Brain Distribution

HDAC2 is widely expressed throughout the brain with particularly high levels in:

• [Hippocampus](/brain-regions/hippocampus): CA1, CA3, dentate gyrus (critical for memory)
• [Cortex](/brain-regions/cortex): Layer 2/3 pyramidal [neurons](/entities/neurons)
• Amygdala: Emotional memory processing
• Basal forebrain: Cholinergic neurons

The expression pattern overlaps with brain regions affected in Alzheimer's disease, making HDAC2 dysregulation particularly relevant to AD pathogenesis.

Role in Synaptic Plasticity and Memory

Histone Acetylation in Memory Formation

Memory formation requires transcriptional activation of plasticity-related genes:

• Immediate early genes: c-Fos, Arc, Egr1
• Synaptic proteins: Synapsin, PSD-95, NMDA receptors
• Growth factors: BDNF, NGF

HDAC2 negatively regulates these genes by maintaining chromatin in a condensed state. During learning, histone acetyltransferases (HATs) such as CBP are recruited to activate memory-related genes, counteracting HDAC2 activity.

HDAC2 in Synaptic Plasticity

HDAC2 modulates both [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and long-term depression (LTD):

LTP Enhancement: HDAC2 deletion or inhibition enhances LTP in hippocampal slices LTD Regulation: HDAC2 is required for certain forms of LTD Dendritic Spine Morphology: HDAC2 regulates spine density and morphology

Cognitive Enhancement

Pharmacological HDAC2 inhibition improves memory in various paradigms:

• Contextual fear conditioning: Enhanced recall with HDAC inhibitors
• Object recognition: Improved novel object recognition
• Spatial memory: Better performance in Morris water maze

Role in Alzheimer's Disease

HDAC2 is significantly upregulated in Alzheimer's disease brain:

Transcriptional Repression in AD

In AD, elevated HDAC2 contributes to:

• Memory gene repression: Reduced expression of synaptic proteins
• Synaptic loss: Decreased PSD-95, synapsin levels
• Neuronal dysfunction: Impaired plasticity-related gene expression

Tau Pathology

HDAC2 interacts with [tau](/proteins/tau) pathology:

• HDAC2 levels correlate with NFT burden: Higher HDAC2 in regions with more tangles
• Tau phosphorylation affects HDAC2: Pathological tau may alter HDAC2 localization
• Therapeutic implications: HDAC2 inhibition may counteract tau-induced transcriptional deficits

Amyloid-beta Effects

[Aβ](/proteins/amyloid-beta) exposure leads to HDAC2 dysregulation:

• Aβ induces HDAC2: Direct and indirect mechanisms
• Synaptic HDAC2 increases: Relocalization to synapses
• Reversal possible: HDAC inhibitors restore function

Therapeutic Targeting

HDAC2-selective inhibitors are being developed for AD:

• Non-selective inhibitors: Vorinostat, sodium butyrate show promise in models
• Selective HDAC2 inhibitors: In development (e.g., BDMC, compound 60)
• Combination approaches: HDAC2 inhibition + [cholinesterase inhibitors](/entities/cholinesterase-inhibitors)

Role in Parkinson's Disease

HDAC2 is implicated in Parkinson's disease pathogenesis:

Alpha-synuclein Toxicity

• [α-synuclein](/proteins/alpha-synuclein) aggregation: HDAC2 may be sequestered in Lewy bodies
• Transcriptional dysregulation: HDAC2 contributes to dopaminergic neuron dysfunction
• HDAC inhibition benefits: HDAC inhibitors protect against α-synuclein toxicity

Dopaminergic Neuron Survival

HDAC2 regulates genes important for dopaminergic neuron survival:

• tyrosine hydroxylase expression: Rate-limiting enzyme in dopamine synthesis
• VMAT2: Vesicular monoamine transporter
• DAT: Dopamine transporter

Neuroinflammation

HDAC2 modulates neuroinflammatory responses:

• Glial activation: Regulates inflammatory gene expression
• Cytokine production: Modulates TNF-α, IL-1β, IL-6
• Therapeutic potential: Anti-inflammatory effects of HDAC inhibition

Role in Depression and Mood Disorders

HDAC2 is dysregulated in depression:

Antidepressant Effects

HDAC2 is a key mediator of antidepressant action:

• HDAC2 decreases with treatment: Chronic antidepressant use reduces HDAC2
• H3/H4 acetylation increases: Enhanced transcription of mood-related genes
• Synaptic plasticity improvements: Increased spine density, synaptic markers

Stress Response

Chronic stress increases HDAC2:

• Stress-induced HDAC2: Glucocorticoids upregulate HDAC2
• Memory impairment: Stress-related memory deficits mediated by HDAC2
• Reversal strategies: HDAC inhibitors block stress effects

HDAC Inhibitors in Clinical Development

Non-selective HDAC Inhibitors

| Drug | Class | Clinical Status | Neurological Use |
|------|-------|-----------------|------------------|
| Vorinostat | Pan-HDAC | Approved (CTCL) | Being studied for AD |
| Valproic acid | Pan-HDAC | Approved (seizures, bipolar) | Being studied for AD |
| Sodium butyrate | Pan-HDAC | Research use | Preclinical AD |
| Entinostat (MS-275) | Class I selective | Clinical trials | Being studied for AD |

Selective HDAC2 Inhibitors

Selective HDAC2 inhibitors are in development:

• Compound 60: First selective HDAC2 inhibitor, reverses memory deficits
• BDMC: Natural product derivative with HDAC2 selectivity
• TMP269: Class IIa HDAC inhibitor with neurological effects

Key Publications

[HDAC2 in memory formation - Nature 2009](https://pubmed.ncbi.nlm.nih.gov/19171937/)

[HDAC2 in Alzheimer's disease - Nat Neurosci 2011](https://pubmed.ncbi.nlm.nih.gov/22057160/)

[HDAC inhibitors for neurodegenerative diseases - Nat Rev Drug Discov 2012](https://pubmed.ncbi.nlm.nih.gov/22410552/)

[HDAC2 and synaptic plasticity - Neuron 2010](https://pubmed.ncbi.nlm.nih.gov/20547134/)

[HDAC2 in depression - Nat Neurosci 2013](https://pubmed.ncbi.nlm.nih.gov/23260146/)

[HDAC2-selective inhibition for cognitive enhancement - J Neurosci 2018](https://pubmed.ncbi.nlm.nih.gov/29386298/)

See Also

• [HDAC2 Gene](/genes/hdac2)
• [HDAC1 Protein](/proteins/hdac1-protein)
• [Histone Acetylation](/mechanisms/histone-acetylation)
• [Epigenetics in Neurodegeneration](/mechanisms/epigenetics-neurodegeneration)
• [Synaptic Plasticity](/mechanisms/synaptic-plasticity)
• [Memory Formation](/mechanisms/memory-formation)
• [CREB Protein](/proteins/creb1-protein)
• [CBP Protein](/proteins/crebbp-protein)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Depression](/diseases/depression)
• [Histone Deacetylase Inhibitors](/therapeutics/histone-deacetylase-inhibitors)

Overview

Hdac2 Protein — Histone Deacetylase 2 plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Background

The study of Hdac2 Protein — Histone Deacetylase 2 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
• [Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
• [Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

References

[Unknown, HDAC2 in memory formation - Nature (n.d.)](https://pubmed.ncbi.nlm.nih.gov/19171937/)

[Unknown, HDAC2 in Alzheimer's disease pathogenesis - Nat Neurosci (n.d.)](https://pubmed.ncbi.nlm.nih.gov/22057160/)

Unknown, -HDAC inhibitors for neurodegenerative diseases - Nat Rev Drug Discov (n.d.)

[Unknown, HDAC2 and synaptic plasticity - Neuron (n.d.)](https://pubmed.ncbi.nlm.nih.gov/20547134/)

[Unknown, HDAC2 in depression - Nat Neurosci (n.d.)](https://pubmed.ncbi.nlm.nih.gov/23260146/)

[Unknown, Selective HDAC2 inhibition for cognitive enhancement - J Neurosci (n.d.)](https://pubmed.ncbi.nlm.nih.gov/29386298/)

[Unknown, HDAC2 structure and function - J Biol Chem (n.d.)](https://pubmed.ncbi.nlm.nih.gov/12716908/)

[Unknown, HDAC2 in Parkinson's disease - Brain (n.d.)](https://pubmed.ncbi.nlm.nih.gov/25480037/)