<div class="infobox infobox-gene">
| | |
|---|---|
| Gene Symbol | EZH2 |
| Full Name | Enhancer of Zeste Homolog 2 |
| Aliases | KMT6, KMT6A, ENX-1 |
| Chromosome | 7q36.1 |
| NCBI Gene ID | [2146](https://www.ncbi.nlm.nih.gov/gene/2146) |
| OMIM | [601573](https://omim.org/entry/601573) |
| Ensembl | [ENSG00000106462](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106462) |
| UniProt | [Q15910](https://www.uniprot.org/uniprot/Q15910) |
| Associated Diseases | [Alzheimer's disease](/diseases/alzheimers-disease), [Huntington's disease](/diseases/huntington-disease), Weaver syndrome, various cancers |
</div>
EZH2 encodes the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), the principal histone H3 lysine 27 (H3K27) methyltransferase in mammalian cells. Through trimethylation of H3K27 (H3K27me3), PRC2 establishes transcriptionally repressive chromatin domains that silence developmental genes, maintain cell identity, and regulate neuronal differentiation. Dysregulation of EZH2-mediated epigenetic silencing is increasingly recognized as a contributor to neurodegenerative disease pathogenesis, particularly in [Alzheimer's disease](/diseases/alzheimers-disease) and [Huntington's disease](/diseases/huntington-disease), where aberrant gene silencing and loss of neuronal identity accelerate neuronal vulnerability.
<div class="infobox infobox-gene">
| | |
|---|---|
| Gene Symbol | EZH2 |
| Full Name | Enhancer of Zeste Homolog 2 |
| Aliases | KMT6, KMT6A, ENX-1 |
| Chromosome | 7q36.1 |
| NCBI Gene ID | [2146](https://www.ncbi.nlm.nih.gov/gene/2146) |
| OMIM | [601573](https://omim.org/entry/601573) |
| Ensembl | [ENSG00000106462](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106462) |
| UniProt | [Q15910](https://www.uniprot.org/uniprot/Q15910) |
| Associated Diseases | [Alzheimer's disease](/diseases/alzheimers-disease), [Huntington's disease](/diseases/huntington-disease), Weaver syndrome, various cancers |
</div>
EZH2 encodes the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), the principal histone H3 lysine 27 (H3K27) methyltransferase in mammalian cells. Through trimethylation of H3K27 (H3K27me3), PRC2 establishes transcriptionally repressive chromatin domains that silence developmental genes, maintain cell identity, and regulate neuronal differentiation. Dysregulation of EZH2-mediated epigenetic silencing is increasingly recognized as a contributor to neurodegenerative disease pathogenesis, particularly in [Alzheimer's disease](/diseases/alzheimers-disease) and [Huntington's disease](/diseases/huntington-disease), where aberrant gene silencing and loss of neuronal identity accelerate neuronal vulnerability.
EZH2 spans approximately 76 kb on chromosome 7q36.1 and contains 20 exons. The gene undergoes alternative splicing, producing short and long isoforms with different catalytic activities. EZH2 expression is high during embryonic development and neural progenitor proliferation but is downregulated in post-mitotic [neurons](/entities/neurons), where EZH1 partially compensates. In aging and neurodegeneration, aberrant re-expression or persistent activity of EZH2 contributes to pathological gene silencing[@margueron2011].
EZH2 catalyzes mono-, di-, and trimethylation of histone H3K27 through its SET domain. H3K27me3 is the transcriptionally repressive mark that defines Polycomb-silenced chromatin. The PRC2 core complex requires EZH2 together with EED, SUZ12, and RBAP46/48 for catalytic activity. Allosteric activation occurs when H3K27me3 on adjacent nucleosomes stimulates PRC2 via EED's aromatic cage, enabling spreading of the repressive mark[@muller2002].
EZH2-PRC2 plays essential roles in neural development. It maintains neural stem cell self-renewal by repressing neuronal differentiation genes in progenitors, controls the neuron-glia fate switch through timed EZH2 downregulation, regulates synaptic gene programs including synaptogenesis and plasticity genes, and specifies cortical layer identity during corticogenesis[@pereira2010].
In mature neurons, residual PRC2 activity (primarily EZH1-containing) maintains repression of pro-apoptotic genes ([BAX](/genes/bax), BIM), non-neuronal lineage genes, transposable elements and repetitive sequences, and cell cycle re-entry genes (aberrant activation of which triggers neuronal death)[@von2016].
Epigenetic dysregulation through EZH2/PRC2 contributes to AD pathogenesis. H3K27me3 accumulates at neuroprotective gene loci ([BDNF](/genes/bdnf), synaptic genes) in AD brain. Nuclear [tau](/proteins/tau) recruits EZH2 to heterochromatin, and pathological [tau](/proteins/tau) disrupts this interaction, causing heterochromatin relaxation and transposable element derepression. Loss of proper PRC2-mediated silencing leads to inappropriate expression of non-neuronal genes, a hallmark of degenerating neurons. EZH2 silences genes that inhibit GSK-3beta, indirectly promoting tau hyperphosphorylation[@frost2014].
PRC2 dysfunction is prominent in [Huntington's disease](/diseases/huntington-disease). Polyglutamine-expanded [huntingtin](/proteins/huntingtin-protein) interacts with PRC2 components, altering genome-wide H3K27me3 patterns. Medium spiny neurons show the greatest PRC2 redistribution and transcriptional dysregulation. Aberrant H3K27me3 at the [BDNF](/genes/bdnf) promoter reduces trophic support critical for striatal neuron survival[@seong2010].
Gain-of-function mutations in EZH2 cause Weaver syndrome (OMIM 277590), characterized by intellectual disability, overgrowth, and distinctive facial features, demonstrating that excessive EZH2 activity is also neurotoxic[@tattonbrown2014].
Age-related changes in EZH2/PRC2 activity contribute to the epigenetic drift hypothesis of neurodegeneration. Progressive loss of H3K27me3 at specific loci with aging, redistribution of PRC2 to inappropriate targets, failure to maintain neuronal identity programs, and increased vulnerability to proteotoxic and oxidative stress are all observed[@nativio2018].
EZH2 expression in the brain shows distinct patterns: high in neural progenitors during development, low but functional in mature neurons, moderate in [microglia](/cell-types/microglia) (regulating inflammatory gene programs), and high in oligodendrocyte precursors (essential for differentiation).
Allen Human Brain Atlas: [EZH2 expression](https://human.brain-map.org/microarray/search/show?search_term=EZH2)
EZH2 is a druggable target with several approved and investigational inhibitors. Tazemetostat (Tazverik) is an FDA-approved EZH2 inhibitor (for cancer) being investigated for neuroprotective applications. GSK126 and EPZ-6438 are research-grade EZH2 inhibitors showing neuroprotection in HD models. EZH2 activators may restore silencing of pro-death genes in some contexts. Combinatorial epigenetic therapy using EZH2 inhibitors with [HDAC inhibitors](/therapeutics/hdac-inhibitors-neurodegeneration) enables balanced epigenetic modulation.
EZH2 catalyzes H3K27 methylation:
EZH2 shows preference for:
EZH2 has functions independent of methyltransferase activity:
EZH2 is targeted in cancer:
Epigenetic therapy approaches:
EZH2 serves critical epigenetic functions:
EZH2 dysfunction contributes to:
Targeting EZH2 offers opportunities:
EZH2 is evolutionarily conserved:
Research uses multiple models:
Key differences across species:
Scientists measure EZH2 through:
Functional studies use:
Key experimental endpoints:
Key questions remain:
Future studies should focus on:
The following diagram shows the key molecular relationships involving EZH2 — Enhancer of Zeste Homolog 2 discovered through SciDEX knowledge graph analysis: