EZH2 Protein

EZH2 Protein

<div class="infobox infobox-protein">

| | |
|---|---|
| Protein Name | EZH2 |
| Gene | [EZH2](/genes/ezh2) |
| UniProt | [Q15910](https://www.uniprot.org/uniprot/Q15910) |
| PDB | [5HYN](https://www.rcsb.org/structure/5HYN), [6C23](https://www.rcsb.org/structure/6C23) |
| Molecular Weight | ~85.4 kDa |
| Length | 746 amino acids |
| Subcellular Localization | Nucleus |
| Protein Family | Polycomb group, SET domain methyltransferases |

</div>

Overview

EZH2 is the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), the principal H3K27 methyltransferase in mammalian cells. EZH2 trimethylates histone H3 at lysine 27 (H3K27me3), establishing transcriptionally repressive chromatin domains that silence developmental genes and maintain cell identity. In the nervous system, EZH2/PRC2 is essential for neural development, neuronal fate specification, and maintenance of neuronal identity throughout life. Dysregulation of EZH2-mediated epigenetic silencing contributes to [Alzheimer's disease](/diseases/alzheimers-disease), [Huntington's disease](/diseases/huntington-disease), and aging-related neurodegeneration[@margueron2011].

Structure

EZH2 Protein

<div class="infobox infobox-protein">

| | |
|---|---|
| Protein Name | EZH2 |
| Gene | [EZH2](/genes/ezh2) |
| UniProt | [Q15910](https://www.uniprot.org/uniprot/Q15910) |
| PDB | [5HYN](https://www.rcsb.org/structure/5HYN), [6C23](https://www.rcsb.org/structure/6C23) |
| Molecular Weight | ~85.4 kDa |
| Length | 746 amino acids |
| Subcellular Localization | Nucleus |
| Protein Family | Polycomb group, SET domain methyltransferases |

</div>

Overview

EZH2 is the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), the principal H3K27 methyltransferase in mammalian cells. EZH2 trimethylates histone H3 at lysine 27 (H3K27me3), establishing transcriptionally repressive chromatin domains that silence developmental genes and maintain cell identity. In the nervous system, EZH2/PRC2 is essential for neural development, neuronal fate specification, and maintenance of neuronal identity throughout life. Dysregulation of EZH2-mediated epigenetic silencing contributes to [Alzheimer's disease](/diseases/alzheimers-disease), [Huntington's disease](/diseases/huntington-disease), and aging-related neurodegeneration[@margueron2011].

Structure

EZH2 contains several functional domains. The SET domain (Su(var)3-9, Enhancer of Zeste, Trithorax) at the C-terminus is the catalytic domain that transfers methyl groups from S-adenosyl methionine (SAM) to H3K27. The CXC domain (cysteine-rich pre-SET region) is required for proper SET domain folding and catalytic activity. The SANT domains (SANT1 and SANT2) mediate histone tail binding and DNA interaction. The EED-binding domain is essential for allosteric activation by EED-bound H3K27me3. The SUZ12-binding domain is required for PRC2 core complex assembly[@muller2002].

EZH2 is catalytically inactive in isolation and requires assembly into the PRC2 core complex (EZH2-EED-SUZ12-RBAP46/48) for methyltransferase activity. Cryo-EM structures reveal that EED binding to H3K27me3 on adjacent nucleosomes allosterically activates EZH2's SET domain, enabling processive spreading of the repressive mark.

Normal Function

Transcriptional Repression

EZH2 establishes H3K27me3 marks at target gene promoters, recruiting PRC1 for chromatin compaction and stable gene silencing. In [neurons](/entities/neurons), PRC2-mediated repression maintains silencing of non-neuronal lineage genes, cell cycle re-entry genes (whose aberrant activation triggers neuronal apoptosis), pro-inflammatory gene programs in resting states, and transposable elements that threaten genomic stability[@von2016].

Neural Development

EZH2 is essential for cortical development, maintaining neural progenitor self-renewal by repressing premature differentiation genes and controlling the timing of neurogenic-to-gliogenic transitions[@pereira2010].

Role in Disease

Alzheimer's Disease

In AD, nuclear [tau](/proteins/tau) normally interacts with EZH2 to maintain heterochromatin integrity. Pathological [tau](/proteins/tau) disrupts this interaction, causing global heterochromatin relaxation, transposable element derepression, and neuronal identity erosion. Simultaneously, aberrant H3K27me3 accumulation at neuroprotective gene promoters ([BDNF](/genes/bdnf), synaptic genes) reduces their expression[@frost2014].

Huntington's Disease

Mutant [huntingtin](/proteins/huntingtin-protein) sequesters PRC2 components, causing genome-wide redistribution of H3K27me3. This is most severe in striatal [medium spiny neurons](/cell-types/medium-spiny-neurons), explaining their selective vulnerability. Aberrant H3K27me3 at the BDNF locus reduces trophic support[@seong2010].

Therapeutic Targeting

EZH2 inhibitors (tazemetostat, GSK126, EPZ-6438) are approved or in clinical trials for cancer and are being investigated for neuroprotection. Context-dependent approaches are needed: EZH2 inhibition may benefit HD (reduce aberrant silencing) but could harm in other settings (loss of protective silencing). Combinatorial epigenetic therapy with [HDAC inhibitors](/therapeutics/hdac-inhibitors-neurodegeneration) may provide balanced modulation[@nativio2018].

See Also

• [EZH2 Gene](/genes/ezh2)
• [HDAC1 Protein](/proteins/hdac1-protein)
• [SIRT1 Protein](/proteins/sirt1-protein)
• [Chromatin Remodeling in Neurodegeneration](/mechanisms/chromatin-remodeling-neurodegeneration)

External Links

• [UniProt: Q15910](https://www.uniprot.org/uniprot/Q15910)
• [PDB: 5HYN](https://www.rcsb.org/structure/5HYN)

References