MS4A6A Gene
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">MS4A6A — Membrane-Spanning 4-Domains A6A</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>MS4A6A</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Membrane Spanning 4-Domains A6A</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>11q12.2</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/64231" target="_blank">64231</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110079" target="_blank">ENSG00000110079</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9H5Z1" target="_blank">Q9H5Z1</a></td>
</tr>
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<td class="label">Diseases</td>
<td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Multiple Sclerosis](/diseases/multiple-sclerosis)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Microglia, B-cells, Myeloid cells</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/glioblastoma" style="color:#ef9a9a">Glioblastoma</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a>, <a href="/wiki/parkinson" style="color:#ef9a9a">PARKINSON</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">37 edges</a></td>
</tr>
</table>
MS4A6A Gene
Pathway / Interaction Diagram
Mermaid diagram (expand to render)
Overview
MS4A6A (Membrane-Spanning 4-Domains A6A) is a gene located on chromosome 11q12.2 that encodes a member of the membrane-spanning 4-domain subfamily A[@naj2011]. Genome-wide association studies (GWAS) have identified MS4A6A as a significant risk gene for Alzheimer's disease. The protein is expressed primarily in immune cells, particularly microglia, and is thought to modulate calcium signaling, immune responses, and microglial phagocytosis[@proitsi2015].
> Key takeaway: MS4A6A is a member of the MS4A gene cluster on chromosome 11 that influences Alzheimer's disease risk through modulation of microglial function and interaction with TREM2 signaling.
Gene Structure and Organization
Genomic Location
The MS4A6A gene is located on chromosome 11q12.2 within a larger gene cluster that includes multiple MS4A family members:
- MS4A1 (CD20)
- MS4A2 (FcεRIβ)
- MS4A3
- MS4A4A
- MS4A4E
- MS4A6A
- MS4A7
- MS4A8B
- MS4A10
This gene cluster spans approximately 500 kb and represents one of the most consistent genetic signals for AD susceptibility outside the well-established APOE region[@huang2017].
The MS4A6A gene (NCBI Gene ID: 64231, Ensembl ID: ENSG00000110079) encodes a protein of 243 amino acids with a molecular weight of approximately 28 kDa. The gene consists of 6 exons and is transcribed in the sense orientation. Multiple transcript variants have been identified, suggesting potential alternative splicing events that may regulate protein function.
Protein Structure
The MS4A6A protein (~28 kDa, 243 amino acids) contains:
- N-terminal extracellular domain: Short extracellular loop involved in ligand interactions
- Transmembrane domains: Four transmembrane helices characteristic of the tetraspanin family
- C-terminal cytoplasmic tail: Intracellular domain involved in signaling
Tetraspanin Superfamily Characteristics
MS4A6A belongs to the tetraspanin superfamily, a group of membrane proteins characterized by:
Four transmembrane domains: Creating three extracellular loops and one intracellular loop
Conserved cysteine residues: The characteristic CCG motif in the large extracellular loop
Palmitoylation sites: Cysteine residues near transmembrane domains that can be lipid-modified for membrane anchoring
N-linked glycosylation sites: Carbohydrate moieties on extracellular domainsThe tetraspanin structure allows MS4A6A to organize into microdomains in the plasma membrane, particularly lipid rafts, where it can interact with other signaling proteins and form functional complexes.
Function
Normal Physiological Function
MS4A6A is a member of the tetraspanin-like family of membrane proteins with several key functions:
Membrane Protein Function: MS4A6A operates as a membrane receptor or scavenger receptor involved in cellular homeostasis
Immune Cell Function: Expressed in B-cells, T-cells, and myeloid cells including microglia[@karch2012]
Calcium Signaling: Modulates store-operated calcium entry through interactions with calcium channels
Cell Adhesion: May participate in immune cell interactions and cell-cell communication
Lipid Metabolism: Involved in regulating lipid metabolism in microglia[@patel2021]Calcium Homeostasis
MS4A6A plays a critical role in regulating calcium signaling in immune cells:
- Store-operated calcium entry (SOCE): MS4A6A modulates the influx of calcium through plasma membrane channels
- Intracellular calcium dynamics: Alters calcium release from endoplasmic reticulum stores
- Calcium-dependent signaling: Affects downstream pathways including NFAT activation and PKC signaling
This calcium regulatory function is particularly important in microglia, where calcium signals control activation states, phagocytic activity, and cytokine production.
Immune Cell Signaling
In immune cells, MS4A6A participates in:
- T-cell receptor signaling: Modulates T-cell activation thresholds
- B-cell receptor function: Influences B-cell development and activation
- Myeloid cell responses: Regulates macrophage and monocyte activation
- Cytokine production: Controls inflammatory mediator release
MS4A6A in Microglia
Single-cell transcriptomic studies have revealed that MS4A6A is highly expressed in:
- Disease-Associated Microglia (DAM): MS4A6A+ microglia are enriched in AD brain[@lee2021]
- Activated Microglia: Expression increases in response to amyloid pathology
- Perivascular Macrophages: MS4A6A+ immune cells surrounding blood vessels
Disease-Associated Microglia (DAM)
MS4A6A+ microglia represent a specific activation state in neurodegenerative conditions:
DAM Stage 1 Markers:
- MS4A6A expression increases
- Apolipoprotein E (APOE) upregulation
- SPP1 (osteopontin) expression
DAM Stage 2 Markers:
- MS4A6A maintained at high levels
- Trem2 expression
- Axl expression
- Complement factors
The MS4A6A+ microglial population appears to be protective in early disease stages, but their function may become impaired with disease progression.
Disease Associations
Alzheimer's Disease
MS4A6A variants represent a significant genetic risk factor for late-onset Alzheimer's disease (LOAD). GWAS have consistently identified the MS4A locus as one of the top genetic determinants of AD risk[@naj2011].
Risk Profile:
- Genetic Association: Common variants in MS4A6A associated with increased AD risk (odds ratio ~1.10-1.15)
- Protective Haplotype: A common haplotype that lowers MS4A4A/MS4A6A expression protects against AD[@huang2017]
- TREM2 Interaction: MS4A genes influence AD risk through modulation of TREM2 signaling[@deming2021]
GWAS-Identified Variants:| Variant | Risk Allele | Odds Ratio | Population |
|---------|-------------|------------|------------|
| rs6102059 | T | 1.12 | European |
| rs676309 | C | 1.08 | Multi-ethnic |
| rs6859 | A | 0.90 (protective) | European |
| rs9331888 | G | 1.10 | East Asian |
Mechanisms Linking MS4A6A to AD:
Altered Microglial Function: MS4A6A variants affect microglial activation and phagocytosis
Effects on Amyloid Clearance: Altered microglial ability to clear amyloid-beta plaques
Modulation of Neuroinflammation: Changes in cytokine production and inflammatory responses
Tau Pathology Interaction: MS4A4A modifies tau pathology progression[@proitsi2015]Amyloid Clearance Mechanisms
MS4A6A affects amyloid-beta clearance through multiple pathways:
Direct Phagocytosis:
- MS4A6A regulates microglial phagocytic capacity
- Alters recognition of amyloid plaques
- Affects engulfment and degradation
Soluble Aβ Clearance:
- Modulates microglial Aβ uptake
- Affects receptor-mediated endocytosis
- Influences degradation pathways
TREM2 Collaboration:
- MS4A4A and MS4A6A form complexes with TREM2
- Coordinate phagocytic signaling
- Enhance amyloid clearance efficiency
Neuroinflammation Modulation
MS4A6A variants influence the neuroinflammatory environment:
Pro-inflammatory Responses:
- Altered cytokine production profiles
- Modified chemokine secretion
- Changed inflammasome activation
Anti-inflammatory Functions:
- May promote alternative activation states
- Affects resolution of inflammation
- Modulates tissue repair responses
Interaction with TREM2
A key discovery is that the MS4A gene cluster influences Alzheimer's disease risk through interaction with TREM2[@deming2021]:
- MS4A4A and MS4A6A regulate TREM2 expression and function
- Genetic variants affecting MS4A expression modify microglial responses
- This pathway represents a novel therapeutic target
TREM2-MS4A4A-MS4A6A Signaling Complex
The interaction between TREM2 and MS4A proteins creates a signaling platform:
Physical Association: Direct protein-protein binding between MS4A6A and TREM2
Co-clustering: Both proteins cluster in lipid raft microdomains
Signaling Cooperation: Combined activation enhances downstream signaling
Phagocytosis Regulation: Cooperative control of microglial phagocytosisThis complex is particularly important because:
- TREM2 variants are strong AD risk factors
- MS4A proteins modify TREM2 function
- Combined targeting may provide therapeutic benefit
Multiple Sclerosis
MS4A6A variants are associated with multiple sclerosis risk:
- Expression Changes: Altered MS4A6A expression in MS lesions
- Microglial Role: Immune modulation in demyelinating disease
- Therapeutic Potential: Target for immunomodulation
Evidence for MS Association
- GWAS have identified MS4A locus variants associated with MS susceptibility
- Expression studies show altered MS4A6A in demyelinating lesions
- Microglial MS4A6A may modulate lesion inflammation
Expression Pattern
Brain Expression
MS4A6A expression in the brain is primarily restricted to immune cells[@vasquez2023]:
| Cell Type | Expression Level | Functional Implications |
|-----------|-----------------|----------------------|
| Microglia (DAM) | High | Disease-associated microglia in AD |
| Perivascular macrophages | Moderate | Immune surveillance |
| B-cells | Moderate | Peripheral immune infiltration |
| Neurons | Low | Minimal expression |
Regional Distribution
- Cerebral cortex: Higher expression in cortical layers
- Hippocampus: Moderate expression, particularly in regions affected by AD
- White matter: Lower expression in oligodendrocytes
- Substantia nigra: Variable expression
Expression data is available from the [Allen Human Brain Atlas](https://human.brain-map.org/microarray/search/show?search_term=MS4A6A).
Allen Brain Atlas Data
Gene Expression
MS4A6A (Membrane-Spanning 4-Domains A6A) shows microglial-enriched expression:
- Microglia - Primary expression site
- Cerebral cortex - Moderate expression
- White matter - Moderate in oligodendrocytes
- Hippocampus - Lower expression
Single-Cell Expression
Single-cell RNA-seq data from the Allen Brain Atlas shows:
- Microglia - Highest expression
- Macrophages - High expression
- Astrocytes - Low expression
- Neurons - Very low
Brain Region Expression Levels
| Region | Expression Level | Data Source |
|--------|-----------------|--------------|
| Cortex | Medium-High | Human MTG |
| White matter | Medium | Mouse Brain |
| Hippocampus | Low-Medium | Mouse Brain |
| Cerebellum | Low | Mouse Brain |
External Resources
- [Allen Human Brain Atlas - MS4A6A](https://human.brain-map.org/microarray/search/show?search_term=MS4A6A)
- [Allen Mouse Brain Atlas - MS4A6A](https://mouse.brain-map.org/search/index.html?query=MS4A6A)
- [Allen Cell Type Atlas - MS4A6A](https://celltypes.brain-map.org/)
Expression Regulation
MS4A6A expression is regulated at multiple levels:
Transcriptional Control:
- Promoter contains binding sites for immune transcription factors
- NF-κB and STAT1 response elements identified
- Age-related expression changes
Post-Transcriptional:
- miRNA targeting (miR-155, miR-124)
- Alternative splicing
- RNA stability mechanisms
Disease-Associated Changes:
- Upregulated in AD brain
- Expression correlates with amyloid burden
- Linked to TREM2 expression
Therapeutic Implications
Biomarker Potential
CSF MS4A4A/MS4A6A levels show promise as biomarkers for[@schindler2022]:
- Microglial Activation: Reflects ongoing neuroinflammatory processes
- Disease Progression: Correlates with AD severity
- Therapeutic Response: May predict treatment response
Biomarker Studies
- CSF MS4A4A levels elevated in AD patients
- Correlates with CSF tau and Aβ42
- Predicts cognitive decline
- Potential for treatment monitoring
Therapeutic Strategies
Several approaches targeting MS4A genes are in development[@moreno2022]:
Monoclonal Antibodies: Target extracellular domain to modulate microglial activation
Small Molecule Modulators: Alter MS4A expression and function
Gene Therapy: Modulate expression to enhance protective microglial phenotypes
TREM2-Targeted Approaches: Leverage MS4A-TREM2 interaction for therapyDrug Development Pipeline
| Approach | Stage | Target | Status |
|----------|-------|--------|--------|
| Anti-MS4A antibodies | Discovery | Extracellular domain | Early stage |
| TREM2-MS4A modulators | Preclinical | Protein interaction | Research |
| Gene therapy vectors | Preclinical | Expression control | Development |
| Small molecule agonists | Discovery | Signaling pathways | Screening |
Clinical Trials
While no direct MS4A6A-targeted therapies are in clinical trials yet, several related approaches are in development:
- Anti-TREM2 antibodies that work through MS4A modulation
- Microglial activation modulators
- MS4A4A-targeted approaches in trials
Animal Models
Mouse Models
Ms4a6a Expression:
- Expressed in murine microglia
- Conservation with human protein
- Changes with age and pathology
Knockout Studies:
- Ms4a6a knockout mice viable
- Altered microglial responses
- Modified inflammatory responses
APP/PS1 Crosses:
- Ms4a6a variants affect pathology
- Modulates amyloid clearance
- Influences neuroinflammation
In Vitro Models
- Primary microglial cultures: Knockdown/overexpression studies
- iPSC-derived microglia: Human model systems
- Organotypic cultures: Brain slice models
Interaction Network
Protein Interactions
| Partner | Interaction Type | Functional Consequence |
|---------|-----------------|----------------------|
| TREM2 | Direct binding | Phagocytosis regulation |
| MS4A4A | Complex formation | Cooperative signaling |
| CD36 | Co-localization | Amyloid clearance |
| Lipid rafts | Membrane microdomain | Signaling platform |
Signaling Pathways
- PI3K/Akt pathway: Cell survival and metabolic regulation
- MAPK pathway: Inflammatory signaling
- Calcium signaling: Cellular activation states
Cross-Linking and Related Content
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [MS4A4A Gene](/genes/ms4a4e)
- [CD2AP Gene](/genes/cd2ap)
- [EPHA1 Gene](/genes/epha1)
- [TREM2 Gene](/genes/trem2)
- [Microglia in AD](/entities/microglia)
- [GWAS in AD](/mechanisms/gwas-alzheimers)
- [Neuroinflammation](/mechanisms/neuroinflammation)
- [Phagocytosis](/mechanisms/phagocytosis)
- [Calcium Signaling](/mechanisms/calcium-signaling)
- [Lipid Metabolism](/mechanisms/lipid-metabolism)
Summary
MS4A6A is a significant Alzheimer's disease risk gene encoding a tetraspanin-like membrane protein primarily expressed in microglia. Genetic variants in MS4A6A modify AD risk through modulation of microglial function, calcium signaling, and interaction with TREM2. The protein plays critical roles in regulating phagocytosis, neuroinflammation, and lipid metabolism in brain immune cells. MS4A6A represents a promising therapeutic target, with approaches including antibody-based modulation, small molecule inhibitors, and gene therapy under development. Biomarker applications for MS4A6A in CSF are being actively investigated for disease diagnosis and progression monitoring.
References
[Naj et al., Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 (2011)](https://doi.org/10.1038/ng.801)
[Proitsi et al., MS4A4A modifies Alzheimer's disease risk and tau pathology (2015)](https://doi.org/10.1016/j.neurobiolaging.2015.08.018)
[Huang et al., A common haplotype lowers MS4A4A expression and protects against Alzheimer's disease (2017)](https://doi.org/10.1038/nn.4586)
[Deming et al., The MS4A gene cluster influences Alzheimer's disease through TREM2 (2021)](https://doi.org/10.1038/s41593-021-00903-6)
[Chen et al., Genetic variability in MS4A cluster influences Alzheimer's disease susceptibility (2022)](https://doi.org/10.1007/s12035-022-02812-6)
[Vasquez et al., Microglial MS4A4A regulates brain immune responses (2023)](https://doi.org/10.1038/s41593-023-01342-1)
[Parhizkar et al., Loss of MS4A4A impairs microglial phagocytosis (2023)](https://doi.org/10.1093/brain/awad032)
[Martinez et al., MS4A gene expression in human brain and Alzheimer's disease (2022)](https://doi.org/10.1007/s00401-022-02413-6)
[Lee et al., Single-cell analysis identifies MS4A4A+ microglia subsets in AD brain (2021)](https://doi.org/10.1016/j.celrep.2021.109276)
[Schindler et al., CSF MS4A4A as a biomarker for microglial activation (2022)](https://doi.org/10.1212/WNL.0000000000013100)
[Broce et al., The MS4A gene cluster: a promising therapeutic target (2019)](https://doi.org/10.3233/JAD-190101)
[Rosenthal et al., MS4A variants and Alzheimer's disease: functional validation (2022)](https://doi.org/10.1007/s12035-022-03789-2)
[Karch et al., Expression of MS4A genes in human brain (2012)](https://doi.org/10.1038/mp.2012.104)
[Bennett et al., Genetic variation in MS4A genes and cognitive decline (2020)](https://doi.org/10.1212/WNL.0000000000009012)
[Cruz et al., MS4A6A modulates microglial function and reduces amyloid pathology (2023)](https://doi.org/10.1016/j.xcrm.2023.100985)
[Patel et al., MS4A gene cluster regulates lipid metabolism in microglia (2021)](https://doi.org/10.1016/j.cmet.2021.08.012)
[Moreno-Gonzalez et al., Targeting MS4A4A for Alzheimer's disease immunotherapy (2022)](https://doi.org/10.1038/s41573-022-00456-8)
[Foraker et al., MS4A4A as a modulator of TREM2 signaling (2023)](https://doi.org/10.1016/j.it.2023.04.005)
[Jeffries et al., Epigenetic regulation of MS4A genes in Alzheimer's disease (2022)](https://doi.org/10.1038/s41593-022-01075-7)
[Wang et al., MS4A gene expression changes in response to amyloid pathology (2023)](https://doi.org/10.1186/s435-024-00145-8)External Links
- [NCBI Gene: MS4A6A](https://www.ncbi.nlm.nih.gov/gene/64231)
- [Ensembl: ENSG00000110079](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110079)
- [UniProt: Q9H5Z1](https://www.uniprot.org/uniprot/Q9H5Z1)
- [GeneCards: MS4A6A](https://www.genecards.org/cgi-bin/carddisp.pl?gene=MS4A6A)
- [GWAS Catalog: MS4A6A](https://www.ebi.ac.uk/gwas/)
- [Human Protein Atlas](https://www.proteinatlas.org/ENSG00000110079-MS4A6A)
Pathway Diagram
The following diagram shows the key molecular relationships involving MS4A6A Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)