| HDAC4 (Histone Deacetylase 4) | |
|---|---|
| Gene | [HDAC4](/genes/hdac4) |
| UniProt ID | P56524 |
| Alternative Names | HD4, HDAC-A |
| PDB Structures | 2VQJ, 5A2T, 6DRM |
| Molecular Weight | 119 kDa (1088 amino acids) |
| Subcellular Localization | Nucleus/Cytoplasm (signal-dependent shuttling) |
| Protein Family | Class IIa Histone Deacetylases |
| Chromosomal Location | 2q37.3 |
| Expression | High in brain, heart, skeletal muscle |
HDAC4 (Histone Deacetylase 4) is a Class IIa histone deacetylase that plays critical roles in epigenetic regulation, synaptic plasticity, and neuronal survival. Encoded by the HDAC4 gene on chromosome 2q37.3, this 1088-amino acid protein is unique among HDACs in its ability to shuttle between the nucleus and cytoplasm in response to cellular signals, allowing it to regulate both transcriptional programs and cytoplasmic signaling pathways[1]. HDAC4 is particularly important in the brain, where it regulates memory-related genes, neuronal development, and responses to cellular stress. Dysregulation of HDAC4 has been implicated in several neurodegenerative diseases, making it an attractive therapeutic target[2].
The Class IIa HDACs (HDAC4, HDAC5, HDAC7, and HDAC9) are distinguished from Class I HDACs by their N-terminal regulatory domains, which mediate protein-protein interactions and signal-dependent nucleocytoplasmic shuttling. HDAC4 is the most studied Class IIa HDAC in the context of neurodegeneration, with substantial evidence linking its dysregulation to Alzheimer's Disease, Huntington's Disease, and Parkinson's Disease[3].
HDAC4 possesses a characteristic bipartite structure[1:1]:
N-terminal Regulatory Domain (residues 1-665): Contains multiple protein-protein interaction motifs:
C-terminal Catalytic Domain (residues 665-1088): Contains the deacetylase activity:
HDAC4 activity and localization are regulated by multiple post-translational modifications:
The HDAC4 catalytic domain adopts a classic HDAC fold with a tunnel-like active site that accommodates acetyl-lysine side chains. The N-terminal regulatory domain is intrinsically disordered in regions, allowing flexible interactions with multiple partners. Crystal structures of HDAC4 catalytic domain (PDB: 2VQJ, 5A2T) reveal the zinc-dependent hydrolase mechanism.
HDAC4 catalyzes histone deacetylation[1:2]:
HDAC4 is uniquely regulated by cellular signaling:
| Transcription Factor | Interaction | Functional Outcome |
|---|---|---|
| MEF2 (Myocyte Enhancer Factor 2) | Direct binding and repression | Suppresses activity-dependent gene programs |
| REST (RE1 Silencing Transcription Factor) | Co-repressor complex | Represses neuronal genes in non-neuronal cells |
| p53 | Deacetylation | Modulates p53-dependent apoptosis |
| STAT3 | Deacetylation | Regulates inflammatory gene expression |
| Runx Family | Interaction | Modulates osteoblast and neuronal differentiation |
In neurons, HDAC4 regulates[4:1][5]:
HDAC4 dysregulation is a prominent feature of Alzheimer's Disease[6][7]:
Nuclear Localization Changes: In AD brains and models:
Synaptic Dysfunction: HDAC4 contributes to synaptic impairment through:
Tau Pathology Interaction: HDAC4 and tau pathology are interrelated[8]:
Therapeutic Implications:
In Huntington's Disease, HDAC4 plays a critical pathogenic role[9]:
Direct Binding: Mutant huntingtin (mHTT) directly interacts with HDAC4:
Transcriptional Dysregulation: HDAC4 contributes to:
Therapeutic Targeting: HDAC4 reduction or inhibition:
HDAC4 modulates neuroinflammatory responses[12]:
| Drug | Selectivity | Stage | Application |
|---|---|---|---|
| Vorinostat (SAHA) | Pan-HDAC | Approved (CTCL) | Research in ND |
| Trichostatin A | Class I/IIa | Research | Preclinical studies |
| HDAC4-selective inhibitors | HDAC4 | Preclinical | AD, HD, PD |
| LMTA-4 | Class IIa-specific | Preclinical | Neuroprotection |
| RCOR1-based peptides | Class IIa | Discovery | Selective targeting |
Haberland M, Montgomery RL, Olson EN. The many roles of histone deacetylases in development and physiology. Nat Rev Genet. 2009. ↩︎ ↩︎ ↩︎
Dietz KC, Casaccia P. HDAC inhibitors and neurodegeneration. Nat Rev Neurosci. 2010. ↩︎
Xu K, Yang ZG, Liu M, et al. Histone deacetylase inhibitors in neurodegenerative diseases. Neuropharmacology. 2011. ↩︎
Sando R, Gounko N, Pieraut S, et al. HDAC4 governs activity-dependent dendritic growth and synaptic plasticity. Nature. 2012. ↩︎ ↩︎
Park J, Bertram K, Gräff J. HDAC4 in synaptic plasticity and memory. Learn Mem. 2019. ↩︎
Kim D, Frank CL, Dobbin MM, et al. Deregulation of HDAC4 participates in the pathogenesis of Alzheimer's disease. Proc Natl Acad Sci USA. 2008. ↩︎
Gonzalez AC, Schultz J, Ratey K, et al. HDAC4 regulates neuronal death in Alzheimer's disease models. Cell Death Dis. 2018. ↩︎
Wang H, Zhou H, Liu Y, et al. HDAC4 and tau pathology in Alzheimer's disease. J Alzheimer's Disease. 2021. ↩︎
Mielcarek M, Benn CL, Mills A, et al. HDAC4 as a key mediator of mutant huntingtin toxicity. Nat Commun. 2013. ↩︎
Hsieh M, Huang Y, Liu H. Class IIa HDACs in Parkinson's disease. Molecular Neurobiology. 2019. ↩︎
Tian W, Zhou J, Shao J, et al. HDAC4 in ALS and motor neuron disease. Brain. 2023. ↩︎
Liu X, Wang Y, Zhang M. HDAC4 and neuroinflammation in neurodegeneration. Glia. 2024. ↩︎