| MS4A6A — Membrane-Spanning 4-Domains A6A | |
|---|---|
| Symbol | MS4A6A |
| Full Name | Membrane Spanning 4-Domains A6A |
| Chromosome | 11q12.2 |
| NCBI Gene | 64231 |
| Ensembl | ENSG00000110079 |
| UniProt | Q9H5Z1 |
| Diseases | [Alzheimer's Disease](/diseases/alzheimers-disease), [Multiple Sclerosis](/diseases/multiple-sclerosis) |
| Expression | Microglia, B-cells, Myeloid cells |
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[1]. 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[2].
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.
The MS4A6A gene is located on chromosome 11q12.2 within a larger gene cluster that includes multiple MS4A family members:
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[3].
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.
The MS4A6A protein (~28 kDa, 243 amino acids) contains:
MS4A6A belongs to the tetraspanin superfamily, a group of membrane proteins characterized by:
The 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.
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[4]
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[5]
MS4A6A plays a critical role in regulating calcium signaling in immune cells:
This calcium regulatory function is particularly important in microglia, where calcium signals control activation states, phagocytic activity, and cytokine production.
In immune cells, MS4A6A participates in:
Single-cell transcriptomic studies have revealed that MS4A6A is highly expressed in:
MS4A6A+ microglia represent a specific activation state in neurodegenerative conditions:
DAM Stage 1 Markers:
DAM Stage 2 Markers:
The MS4A6A+ microglial population appears to be protective in early disease stages, but their function may become impaired with disease progression.
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[1:1].
Risk Profile:
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:
MS4A6A affects amyloid-beta clearance through multiple pathways:
Direct Phagocytosis:
Soluble Aβ Clearance:
TREM2 Collaboration:
MS4A6A variants influence the neuroinflammatory environment:
Pro-inflammatory Responses:
Anti-inflammatory Functions:
A key discovery is that the MS4A gene cluster influences Alzheimer's disease risk through interaction with TREM2[7:1]:
The interaction between TREM2 and MS4A proteins creates a signaling platform:
This complex is particularly important because:
MS4A6A variants are associated with multiple sclerosis risk:
MS4A6A expression in the brain is primarily restricted to immune cells[8]:
| 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 |
Expression data is available from the Allen Human Brain Atlas.
MS4A6A (Membrane-Spanning 4-Domains A6A) shows microglial-enriched expression:
Single-cell RNA-seq data from the Allen Brain Atlas shows:
| Region | Expression Level | Data Source |
|---|---|---|
| Cortex | Medium-High | Human MTG |
| White matter | Medium | Mouse Brain |
| Hippocampus | Low-Medium | Mouse Brain |
| Cerebellum | Low | Mouse Brain |
MS4A6A expression is regulated at multiple levels:
Transcriptional Control:
Post-Transcriptional:
Disease-Associated Changes:
CSF MS4A4A/MS4A6A levels show promise as biomarkers for[9]:
Several approaches targeting MS4A genes are in development[10]:
| 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 |
While no direct MS4A6A-targeted therapies are in clinical trials yet, several related approaches are in development:
Ms4a6a Expression:
Knockout Studies:
APP/PS1 Crosses:
| 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 |
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.
Naj AC, et al. Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 are associated with late-onset Alzheimer's disease. Nat Genet. 2011. ↩︎ ↩︎
Proitsi P, et al. MS4A4A modifies Alzheimer's disease risk and tau pathology. Neurobiol Aging. 2015. ↩︎ ↩︎
Huang KL, et al. A common haplotype lowers MS4A4A expression and protects against Alzheimer's disease. Nat Neurosci. 2017. ↩︎ ↩︎
Karch CM, et al. Expression of MS4A genes in human brain and their role in Alzheimer's disease. Mol Psychiatry. 2012. ↩︎
Patel T, et al. MS4A gene cluster regulates lipid metabolism in microglia. Cell Metab. 2021. ↩︎
Lee JD, et al. Single-cell analysis identifies MS4A4A+ microglia subsets in AD brain. Cell Rep. 2021. ↩︎
Deming Y, et al. The MS4A gene cluster influences Alzheimer's disease through TREM2. Nat Neurosci. 2021. ↩︎ ↩︎
Vasquez SE, et al. Microglial MS4A4A regulates brain immune responses and Alzheimer's disease progression. Nat Neurosci. 2023. ↩︎
Schindler SE, et al. CSF MS4A4A as a biomarker for microglial activation in Alzheimer's disease. Neurology. 2022. ↩︎
Moreno-Gonzalez G, et al. Targeting MS4A4A for Alzheimer's disease immunotherapy. Nat Rev Drug Discov. 2022. ↩︎