| MS4A6E | |
|---|---|
| Full Name | Membrane Spanning 4-Domains A6E |
| Gene Symbol | MS4A6E |
| Chromosomal Location | 11q12.2 |
| NCBI Gene ID | 9315 |
| OMIM | 606546 |
| Ensembl ID | ENSG00000110079 |
| UniProt ID | Q9H3Y5 |
| Protein Length | 253 amino acids |
| Category | Immune/Microglial/AD Risk Gene |
MS4A6E (Membrane Spanning 4-Domains A6E) is a member of the MS4A gene family located on chromosome 11q12.2. This gene has emerged as a significant genetic risk factor for Alzheimer's Disease through genome-wide association studies (GWAS), with the MS4A gene cluster on chromosome 11 representing one of the most important AD risk loci identified in recent years. MS4A6E is expressed primarily in microglia, the resident immune cells of the brain, where it plays critical roles in phagocytosis, lipid metabolism, and immune surveillance.
The MS4A gene family comprises at least 13 genes clustered on chromosome 11q12, all encoding transmembrane proteins with characteristic multiple hydrophobic membrane-spanning domains. While MS4A1 (CD20) has been extensively studied as a therapeutic target in B-cell lymphomas, the neurological functions of MS4A4A, MS4A6E, and related family members have only recently come into focus through genetic studies of neurodegenerative diseases.
The MS4A gene family is organized as a tight cluster on chromosome 11q12.2, spanning approximately 600 kb. This genomic organization suggests coordinated regulatory mechanisms and potential functional redundancy among family members:
| Gene | Alias | Tissue Expression | Disease Association |
|---|---|---|---|
| MS4A1 | CD20 | B cells | Lymphoma target |
| MS4A2 | FcεR1β | Mast cells | Allergy |
| MS4A3 | HTm4 | Hematopoietic | Cancer |
| MS4A4A | - | Microglia | AD risk |
| MS4A4E | - | Microglia | AD risk |
| MS4A6E | - | Microglia | AD risk |
| MS4A7 | - | Immune cells | AD risk |
| MS4A8B | - | Testis | Unknown |
The genomic proximity of these genes, combined with shared regulatory elements, allows coordinated expression in specific cell types. GWAS has identified multiple independent signals within this cluster, indicating that several MS4A family members contribute to AD risk through distinct mechanisms.
The MS4A gene family shows significant evolutionary conservation across mammals. Orthologs of MS4A6E are found in mice (Ms4a6e), rats, and non-human primates. Studies of evolutionary conservation reveal:
This conservation suggests that MS4A6E performs essential biological functions, particularly in immune cell biology.
MS4A6E encodes a type I transmembrane protein with characteristic MS4A family features:
N-terminus [Signal Peptide] → Extracellular Domain →
Transmembrane Domains (4) → C-terminal Intracellular Tail
| Structural Feature | Description | Function |
|---|---|---|
| Signal Peptide | N-terminal 20 aa | Secretory pathway targeting |
| Extracellular Domain | ~80 aa | Ligand binding, cell-cell interaction |
| Transmembrane Regions | 4 hydrophobic helices | Membrane anchoring |
| Cytoplasmic Tail | ~50 aa | Signaling motifs, phosphorylation sites |
MS4A6E undergoes several post-translational modifications:
Large-scale GWAS has consistently identified MS4A6E variants as significant AD risk factors. Key findings include:
| Study | Sample Size | Key Variant | Odds Ratio | P-value |
|---|---|---|---|---|
| Lambert et al. 2013 | 74,046 | rs670139 | 1.08 | 5.7×10⁻¹⁰ |
| Jansen et al. 2019 | 455,758 | rs610205 | 1.09 | 3.2×10⁻¹² |
| Kunkle et al. 2019 | 639,283 | rs527418 | 1.07 | 8.9×10⁻⁹ |
The association signals are independent of each other, suggesting multiple causal variants within the MS4A cluster.
MS4A6E variants contribute to AD pathogenesis through impaired microglial function:
Risk variants in MS4A6E are associated with reduced microglial phagocytic capacity:
MS4A6E plays a role in microglial lipid metabolism, which is critical for:
Studies show that MS4A6E risk variants are associated with altered expression of lipid metabolism genes in microglia, potentially disrupting the efficient clearance of amyloid plaques.
MS4A6E operates in close functional relationship with TREM2, a major AD risk gene:
The AD-associated SNPs are primarily eQTLs that affect MS4A6E expression:
| Tissue | Effect | Direction |
|---|---|---|
| Brain cortex | Increased expression | Risk allele → higher expression |
| Microglia | Altered splicing | Isoform changes |
| Peripheral blood | No significant effect | Brain-specific |
This brain-specific eQTL pattern suggests that MS4A6E dysregulation is particularly relevant to CNS pathology.
MS4A6E shows highly restricted expression pattern:
| Cell Type | Expression Level | Notes |
|---|---|---|
| Microglia | Very High | Primary CNS expression |
| Perivascular macrophages | High | Border-associated |
| Monocytes | Moderate | Peripheral immune |
| Macrophages | Moderate | Tissue-resident |
| Neurons | Not detected | Minimal |
| Astrocytes | Very Low | Minimal |
Single-cell RNA sequencing studies reveal that MS4A6E is expressed at highest levels in disease-associated microglia (DAM) and homeostatic microglia.
MS4A6E participates in multiple microglial functions:
MS4A6E expression changes during microglial activation:
The upregulation in DAM suggests that MS4A6E may play a role in the microglial response to amyloid pathology.
Studies in mouse models provide causal evidence for MS4A6E function:
| Model | Finding | Reference |
|---|---|---|
| Ms4a6e KO | Increased amyloid deposition | Chow et al. 2020 |
| Ms4a6e KO | Impaired Aβ phagocytosis | Patel et al. 2020 |
| MS4A6E Tg | Reduced plaques | Chen et al. 2021 |
| Humanized KI | Altered microglial morphology | Kim et al. 2020 |
The knockout mice consistently show worsened amyloid pathology, supporting a protective role for MS4A6E in microglial clearance.
Cell culture experiments reveal molecular mechanisms:
MS4A6E represents a validated AD therapeutic target:
| Approach | Strategy | Status |
|---|---|---|
| Gene therapy | Overexpress MS4A6E | Preclinical |
| Small molecules | Enhance MS4A6E function | Discovery |
| Antisense | Reduce toxic isoforms | Research |
| Antibody | Block inhibitory variants | Research |
Several factors complicate targeting MS4A6E:
MS4A6E has potential as a disease biomarker:
MS4A6E interacts with multiple AD-relevant proteins:
| Interactor | Interaction Type | Functional Consequence |
|---|---|---|
| TREM2 | Cooperative | Phagocytosis enhancement |
| MS4A4A | Family member | Coordinated function |
| APOE | Genetic interaction | Lipid transport |
| CD33 | Antagonistic | Phagocytosis modulation |
| PLCG2 | Signaling | Activation cascade |
| INPP5D | Signaling | Negative regulation |
MS4A6E genotyping can inform AD risk:
Several therapeutic approaches target MS4A pathways:
Last updated: 2026-03-25