SMARCA4

📖 Wiki Page

gene1049 wordssynced 2026-04-02

SMARCA4

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SMARCA4</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SMARCA4</td>
</tr>
<tr>
<td class="label">HGNC ID</td>
<td>11100</td>
</tr>
<tr>
<td class="label">Entrez ID</td>
<td>6597</td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td>ENSG00000127616</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>19p13.2</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>Protein-coding</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>[BRG1 protein](/proteins/brg1-protein)</td>
</tr>
<tr>
<td class="label">Key Domains</td>
<td>QLQ, HSA, BRK, DEXDc, HELICc, Bromodomain</td>
</tr>
<tr>
<td class="label">Function</td>
<td>ATP-dependent chromatin remodeling ATPase</td>
</tr>
<tr>
<td class="label">Disease Associations</td>
<td>[Alzheimer's disease](/diseases/alzheimers-disease), Coffin-Siris syndrome type 4, rhabdoid tumors, [Parkinson's disease](/diseases/parkinsons-disease)</td>
</tr>
<tr>
<td class="label">Variant</td>
<td>Type</td>
</tr>
<tr>
<td class="label">ATPase domain missense</td>
<td>Dominant negative</td>
</tr>
<tr>
<td class="label">rs12611091</td>
<td>Intronic</td>
</tr>
<tr>
<td class="label">Reduced expression</td>
<td>Epigenetic</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/

...

SMARCA4

SMARCA4 (SWI/SNF Related, Matrix Associated, Actin Dependent Regulator of Chromatin, Subfamily A, Member 4)

</div>

Pathway Diagram

Mermaid diagram (expand to render)

Knowledge graph relationships for SMARCA4 (306 total edges in KG)

Overview

SMARCA4 is a human gene. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.

SMARCA4, also known as BRG1 (Brahma-Related Gene 1), encodes the catalytic ATPase subunit of the BAF, PBAF, and ncBAF [chromatin remodeling](/mechanisms/chromatin-remodeling-neurodegeneration) complexes. SMARCA4 uses the energy of ATP hydrolysis to mobilize nucleosomes, creating accessible chromatin at gene regulatory elements.[@mashtalir2018] In the nervous system, SMARCA4 is the predominant SWI/SNF ATPase in postmitotic [neurons](/entities/neurons), where it is essential for activity-dependent gene expression, synaptic plasticity, and neuronal survival. Dysfunction of SMARCA4 is linked to [Alzheimer's disease](/diseases/alzheimers-disease) through impaired chromatin remodeling at neuroprotective gene loci and disruption of the neuronal [epigenetic](/mechanisms/epigenetics-neurodegeneration) landscape.

Gene Structure and Expression

The SMARCA4 gene spans approximately 80 kb on chromosome 19p13.2 and contains 35 exons encoding a 1647-amino acid protein. SMARCA4 is broadly expressed across all human tissues. In the brain, expression is highest in the cerebral [cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus), and cerebellum. During neural development, a critical switch occurs from [SMARCA2](/genes/smarca2) (BRM) to SMARCA4 (BRG1) as neural progenitors exit the cell cycle and differentiate into postmitotic neurons.

Single-cell RNA sequencing of adult human brain tissue reveals SMARCA4 expression in all neuronal and glial cell types, with the highest levels in excitatory neurons and oligodendrocytes. In the aging brain, SMARCA4 expression declines selectively in hippocampal CA1 pyramidal neurons and [entorhinal cortex](/brain-regions/entorhinal-cortex) neurons — the cell populations most vulnerable to [Alzheimer's disease](/diseases/alzheimers-disease).[@nativio2018]

Protein Function and Mechanism

SMARCA4/BRG1 is the catalytic engine of three distinct SWI/SNF complexes:

cBAF (canonical BAF): Contains [ARID1A](/genes/arid1a) or [ARID1B](/genes/arid1b), [SMARCB1](/genes/smarcb1), DPF2[@lessard2007]
PBAF (Polybromo BAF): Contains ARID2, PBRM1, BRD7, PHF10
ncBAF (non-canonical BAF): Contains BRD9, GLTSCR1/1L

The ATPase domain of SMARCA4 belongs to the SNF2/SWI2 helicase superfamily and catalyzes three modes of nucleosome remodeling:

Nucleosome sliding: Translocation of histone octamers along DNA

Nucleosome ejection: Complete removal of histones from DNA

Histone variant exchange: Replacement of canonical histones with variants (e.g., H2A.Z)[@mashtalir2018]

In neurons, SMARCA4 is recruited to activity-dependent enhancers and promoters by transcription factors such as CREB, MEF2, and AP-1, enabling rapid transcriptional responses to neuronal stimulation. This is critical for:

[Long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and memory formation
Experience-dependent synaptic plasticity
Neuroprotective gene expression under stress

Role in Neurodegeneration

Alzheimer's Disease

SMARCA4 dysfunction contributes to AD pathogenesis through multiple mechanisms:

Impaired activity-dependent transcription: Reduced SMARCA4 levels in AD hippocampal neurons compromise activity-dependent chromatin remodeling at enhancers of synaptic plasticity genes ([ARC](/genes/arc), [BDNF](/genes/bdnf), [FOS](/genes/fos)), contributing to synaptic dysfunction and memory impairment.[@vogelciernia2013]

[Amyloid-beta](/proteins/amyloid-beta) toxicity: Exposure to oligomeric amyloid-beta reduces SMARCA4 nuclear levels through proteasomal degradation, creating a chromatin accessibility deficit at neuroprotective gene loci. This represents an early event in AD pathogenesis preceding overt neurodegeneration.[@nativio2018][@gjoneska2015]

[Tau](/proteins/tau)-mediated nuclear dysfunction: Pathological [tau](/proteins/tau) disrupts nuclear architecture and SMARCA4 localization, contributing to the [epigenetic dysregulation](/mechanisms/epigenetic-dysregulation-pathway) observed in tauopathies.[@nativio2018]

Neuroinflammation: In [microglia](/cell-types/microglia), SMARCA4-BAF complexes regulate the transition between homeostatic and disease-associated states. Loss of SMARCA4 function promotes a chronic pro-inflammatory microglial phenotype.[@gjoneska2015]

DNA damage accumulation: SMARCA4 facilitates DNA double-strand break repair through nucleosome remodeling at damage sites. Reduced SMARCA4 activity leads to accumulation of DNA damage in aging neurons, a hallmark of AD.[@nativio2018][@gjoneska2015]

Parkinson's Disease

SMARCA4 maintains expression of dopaminergic neuron identity genes, including [TH](/genes/th), DDC, and NURR1. Reduced SMARCA4 activity in substantia nigra neurons may contribute to dopaminergic neurodegeneration in [Parkinson's disease](/diseases/parkinsons-disease).[@sokpor2017]

Coffin-Siris Syndrome

Heterozygous missense mutations in SMARCA4 (typically in the ATPase domain) cause Coffin-Siris syndrome type 4, confirming the dosage sensitivity of SMARCA4 in neural development.[@tsurusaki2012]

Common Variants and Risk Alleles

Therapeutic Implications

SMARCA4 activators: Small molecules that stabilize or enhance SMARCA4 ATPase activity could restore chromatin remodeling in aging neurons.
PROTAC avoidance: Given SMARCA4's neuroprotective role, drugs targeting SMARCA4 for degradation in cancer contexts must be carefully evaluated for neurological side effects.
[HDAC](/entities/hdac-enzymes) inhibitors: [Epigenetic therapies](/therapeutics/epigenetic-therapies-neurodegeneration) that increase histone acetylation can partially compensate for reduced SMARCA4-mediated chromatin remodeling.
Gene therapy: Targeted SMARCA4 expression restoration in vulnerable neuronal populations using cell-type-specific AAV vectors is under preclinical investigation.

External Links

[OMIM: 603254](https://omim.org/entry/603254)
[GeneCards: SMARCA4](https://www.genecards.org/cgi-bin/carddisp.pl?gene=SMARCA4)
[UniProt: P51532](https://www.uniprot.org/uniprot/P51532)

References

[Tsurusaki et al., Mutations affecting components of the SWI/SNF complex cause Coffin-Siris syndrome (2012) (2012)](https://doi.org/10.1038/ng.2229)

[Nativio et al., Dysregulation of the epigenetic landscape of normal aging in Alzheimer's disease (2018) (2018)](https://doi.org/10.1038/s41593-018-0101-9)

[Unknown, Kadoch & Crabtree, Mammalian SWI/SNF chromatin remodeling complexes and cancer (2015) (2015)](https://doi.org/10.1016/j.tig.2015.09.009)

[Mashtalir et al., Modular organization and assembly of SWI/SNF family chromatin remodeling complexes (2018) (2018)](https://doi.org/10.1016/j.cell.2018.09.032)

[Lessard et al., An essential switch in subunit composition of a chromatin remodeling complex during neural development (2007) (2007)](https://doi.org/10.1016/j.neuron.2007.06.019)

[Davies et al., Study of 300,486 individuals identifies 148 independent genetic loci influencing general cognitive function (2018) (2018)](https://doi.org/10.1038/s41467-018-04362-x)

[Wu et al., Understanding of SMARCA4-deficient undifferentiated tumors (2020) (2020)](https://doi.org/10.1016/j.ccell.2020.01.014)

[Vogel-Ciernia et al., The neuron-specific chromatin regulatory subunit BAF53b is necessary for synaptic plasticity and memory (2013) (2013)](https://doi.org/10.1038/nn.3407)

[Gjoneska et al., Conserved epigenomic signals in mice and humans reveal immune basis of Alzheimer's disease (2015) (2015)](https://doi.org/10.1038/nature14252)

[Sokpor et al., Chromatin remodeling BAF complex subunit alterations in neural development (2017) (2017)](https://doi.org/10.3389/fnmol.2017.00243)

Pathway Diagram

The following diagram shows the key molecular relationships involving SMARCA4 discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

📖 View canonical wiki page →

SMARCA4

SMARCA4

SMARCA4

Pathway Diagram

Overview

Gene Structure and Expression

Protein Function and Mechanism

Role in Neurodegeneration

Alzheimer's Disease

Parkinson's Disease

Coffin-Siris Syndrome

Common Variants and Risk Alleles

Therapeutic Implications

See Also

External Links

References

Pathway Diagram