Affinage

MS4A4A

Membrane-spanning 4-domains subfamily A member 4A · UniProt Q96JQ5

Length
239 aa
Mass
25.4 kDa
Annotated
2026-06-10
13 papers in source corpus 10 papers cited in narrative 10 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MS4A4A is a plasma-membrane tetraspan protein selectively expressed in macrophage-lineage cells, induced during monocyte-to-macrophage differentiation and restricted to M2 (IL-4-polarized) rather than M1 macrophages (PMID:28303902). It functions as a lipid-raft scaffold that organizes receptor signaling complexes: it physically interacts and colocalizes with the β-glucan receptor dectin-1 in macrophage lipid rafts and is required for dectin-1-dependent activation, with its loss impairing effector molecule production and NK cell-mediated control of metastasis (PMID:31263276). In mast cells, MS4A4A interacts with caveolin-1 to recruit FcεRI and KIT into lipid rafts, driving PLCγ1 phosphorylation, Orai1-mediated store-operated calcium entry, and degranulation (PMID:32240745). MS4A4A promotes M2 macrophage polarization through PI3K/AKT and JAK/STAT6 signaling (PMID:37507218) as well as NF-κB/STAT6 signaling, and macrophage MS4A4A drives a pro-tumoral microenvironment in liver cancer and glioma (PMID:37507218, PMID:42056558). In microglia, MS4A4A interacts with and stabilizes MS4A6A, which complexes with and blocks DAP12 to post-transcriptionally suppress TREM2 levels and thereby limit microglial phagocytosis and lysosomal function (PMID:41435829); consistent with this, its cytosolic fragment anchors to cytoskeletal components to support phagocytosis, calcium influx, and mitochondrial fitness (PMID:40349168). In amyloid pathology models, Ms4a4a deletion lowers steady-state amyloid-β and plaque burden while rendering microglia more pro-inflammatory (PMID:40843775).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2017 Medium

    Established where MS4A4A protein resides and which myeloid states express it, defining it as a differentiation- and polarization-restricted plasma-membrane marker.

    Evidence Monoclonal antibodies against extracellular epitopes with flow cytometry of human blood and in vitro monocyte differentiation

    PMID:28303902

    Open questions at the time
    • No molecular function assigned at this stage
    • Mechanism of M2-restricted induction not defined
  2. 2019 High

    Showed MS4A4A acts upstream of an innate immune receptor, answering how a tetraspan scaffold contributes to macrophage activation by partnering with dectin-1 in lipid rafts.

    Evidence Lipid-raft co-localization/interaction, Ms4a4a-deficient macrophage signaling and effector assays, in vivo metastasis models with genetic KO

    PMID:31263276

    Open questions at the time
    • Direct binding interface with dectin-1 not mapped
    • Whether MS4A4A organizes other receptors not addressed here
  3. 2020 High

    Extended the raft-scaffold model beyond macrophages, showing MS4A4A recruits FcεRI/KIT via caveolin-1 to drive PLCγ1/SOCE-dependent mast cell degranulation.

    Evidence siRNA knockdown in human mast cells, phosphorylation/Ca2+/degranulation assays, caveolin-1 Co-IP, lipid raft fractionation

    PMID:32240745

    Open questions at the time
    • Knockdown rather than genetic KO
    • Stoichiometry of MS4A4A–caveolin-1–receptor complexes unresolved
  4. 2020 Medium

    Linked MS4A4A to type-2 inflammation in vivo, showing it controls IL-4-induced arginase 1 and allergic eosinophil infiltration.

    Evidence Ms4a4a-deficient mice, IL-4 macrophage stimulation, house dust mite intranasal challenge

    PMID:32589266

    Open questions at the time
    • Molecular link between MS4A4A and arginase 1 regulation unclear
    • Limited mechanistic detail
  5. 2023 Medium

    Defined the intracellular signaling output of MS4A4A in tumor-associated macrophages, implicating PI3K/AKT and JAK/STAT6 in M2 polarization and validating MS4A4A as an antibody-targetable node.

    Evidence RNA-seq, western blot, flow cytometry, murine tumor models with MS4A4A inhibition and anti-MS4A4A antibody

    PMID:37507218

    Open questions at the time
    • How MS4A4A engages PI3K/AKT and JAK/STAT6 mechanistically not shown
    • Single lab
  6. 2025 High

    Uncovered an intracellular regulatory circuit, showing MS4A4A stabilizes MS4A6A, which blocks DAP12 to post-transcriptionally suppress TREM2 and constrain microglial function.

    Evidence CRISPR KO/OE, degrading antibodies, MS4A4A–MS4A6A and MS4A6A–DAP12 Co-IP, NHP/mouse amyloid models, phagocytosis/lysosomal assays

    PMID:41435829

    Open questions at the time
    • Mechanism by which MS4A6A degrades/blocks DAP12 not fully defined
    • Direct vs indirect effect on TREM2 turnover
  7. 2025 Medium

    Connected MS4A4A's microglial role to cellular machinery, showing its cytosolic fragment anchors to the cytoskeleton to support phagocytosis, calcium influx, and mitochondrial fitness.

    Evidence Ms4a4a KO mouse, phagocytosis/calcium/mitochondrial assays, cytoskeletal anchoring experiments, LNP-IL-4 rescue in AD seizure model

    PMID:40349168

    Open questions at the time
    • Cytoskeletal binding partners not identified
    • Causal chain from cytoskeleton to calcium/mitochondria unresolved
  8. 2025 Medium

    Demonstrated functional consequence of MS4A4A loss on amyloid handling, showing deletion lowers Aβ and plaque burden while making microglia more pro-inflammatory.

    Evidence Ms4a4a KO in 5xFAD mice, Aβ half-life and plaque quantification, microglial inflammatory and MMP-9 profiling, human CSF corroboration

    PMID:40843775

    Open questions at the time
    • Whether MMP-9 mechanistically drives Aβ clearance not proven
    • Single lab
  9. 2025 Medium

    Revealed a context where MS4A4A modulates drug response, showing its corticosteroid-induced upregulation counteracts therapeutic activity in arthritis.

    Evidence Ms4a4a-deficient mice in experimental arthritis, corticosteroid treatment of human/murine macrophages, IHC, RNA-seq

    PMID:40924449

    Open questions at the time
    • Mechanism linking MS4A4A to corticosteroid resistance not defined
    • No effect on disease course alone
  10. 2026 Medium

    Reinforced the pro-tumoral macrophage role, implicating NF-κB/STAT6 signaling in MS4A4A-driven M2 polarization and glioma progression/temozolomide resistance.

    Evidence MS4A4A KD/OE in macrophages, western blot for NF-κB/STAT6, co-culture invasion/proliferation assays, glioma mouse models

    PMID:42056558

    Open questions at the time
    • How MS4A4A activates NF-κB not shown
    • Reconciliation of multiple signaling axes (PI3K/AKT vs NF-κB) across tumor types

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis by which MS4A4A organizes raft receptor complexes and transmits signals to its multiple downstream pathways remains undefined.
  • No structural model of MS4A4A or its receptor complexes
  • Direct binding interfaces with dectin-1, caveolin-1, MS4A6A not mapped
  • Unifying mechanism linking raft scaffolding to PI3K/AKT, JAK/STAT6, and NF-κB outputs unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0008092 cytoskeletal protein binding 1
Localization
GO:0005886 plasma membrane 3 GO:0005856 cytoskeleton 1
Pathway
R-HSA-168256 Immune System 3 R-HSA-162582 Signal Transduction 2

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2019 MS4A4A physically interacts and colocalizes with the β-glucan receptor dectin-1 in lipid rafts of macrophages; Ms4a4a-deficient macrophages show defective dectin-1 signaling and defective production of effector molecules in response to dectin-1 ligands, placing MS4A4A upstream of dectin-1-dependent activation and NK cell-mediated metastasis control. Co-localization/interaction studies in lipid rafts, Ms4a4a-deficient macrophage functional assays (signaling readouts, effector molecule production), in vivo tumor metastasis models with genetic knockout Nature immunology High 31263276
2020 In human mast cells, MS4A4A promotes phosphorylation of PLCγ1, calcium flux, and degranulation in response to IgE-mediated FcεRI crosslinking; MS4A4A interacts with caveolin-1 and facilitates recruitment of FcεRI and KIT into lipid rafts; MS4A4A also regulates Orai1-mediated store-operated Ca2+ entry (SOCE) downstream of Ca2+ store release. siRNA knockdown in human mast cells, phosphorylation assays (western blot), calcium flux measurements, degranulation assays, co-immunoprecipitation with caveolin-1, lipid raft fractionation Cellular signalling High 32240745
2020 MS4A4A regulates expression of arginase 1 in macrophages under IL-4 stimulation and regulates eosinophil infiltration during lung allergic inflammation (house dust mite model) in mice. Ms4a4a-deficient mice, in vitro macrophage stimulation with IL-4, in vivo intranasal house dust mite challenge model with cellular readouts European journal of immunology Medium 32589266
2023 MS4A4A promotes M2 polarization of macrophages by activating the PI3K/AKT and JAK/STAT6 signaling pathways; MS4A4A blockade in vivo reshapes the tumor immune microenvironment by reducing M2-TAM infiltration and increasing effector CD8+ T-cell infiltration. RNA sequencing, western blot analysis, flow cytometry, in vivo murine subcutaneous and orthotopic tumor models with MS4A4A inhibition and anti-MS4A4A monoclonal antibody treatment Gut Medium 37507218
2025 MS4A4A interacts with MS4A6A and protects it from degradation; MS4A6A in turn forms a complex with and blocks the co-receptor DAP12, which modulates levels and signaling of TREM2 and other receptors; thereby MS4A4A and MS4A6A cooperatively act as post-transcriptional negative regulators of both transmembrane and soluble TREM2 and of microglial viability, phagocytosis, and lysosomal function. CRISPR knockout and overexpression of MS4A4A in macrophages/microglia, MS4A4A-degrading antibodies, co-immunoprecipitation (MS4A4A–MS4A6A and MS4A6A–DAP12 complexes), non-human primate and mouse amyloid pathology models, flow cytometry, functional phagocytosis/lysosomal assays Neuron High 41435829
2025 Ms4a4a deletion in a 5xFAD mouse model reduces steady-state amyloid-β levels, shortens Aβ half-life in brain interstitial fluid, increases plaque compaction, and reduces overall plaque burden; microglia lacking Ms4a4a are more pro-inflammatory and produce elevated MMP-9, which may facilitate Aβ degradation. Ms4a4a knockout in 5xFAD mice, brain interstitial fluid Aβ half-life measurement, plaque burden quantification, microglial inflammatory profiling, MMP-9 measurement (mouse and human CSF) Alzheimer's & dementia Medium 40843775
2025 Ms4a4a deletion impairs microglial phagocytosis, diminishes calcium influx, and disrupts mitochondrial metabolic fitness; the cytosolic fragment of Ms4a4a is anchored to cytoskeletal components, supporting its role in mediating phagocytosis; induction of Ms4a4a via central LNP-Il4 delivery alleviates seizure conditions in an AD mouse model. Ms4a4a knockout mouse model, microglial phagocytosis assays, calcium influx measurements, mitochondrial metabolic assays, cytoskeletal anchoring experiments, in vivo LNP-IL-4 delivery with seizure readout Advanced science Medium 40349168
2025 In a mouse model of arthritis, Ms4a4a deletion does not alter disease course but is associated with enhanced therapeutic response specifically to corticosteroids; corticosteroids enhance expression of MS4A4A and FcγR3 in macrophages in vitro and in vivo, suggesting MS4A4A upregulation by corticosteroids counteracts their therapeutic activity. Ms4a4a-deficient mice in experimental arthritis model, in vitro corticosteroid treatment of human and murine macrophages, immunohistochemistry, RNA sequencing Proceedings of the National Academy of Sciences of the United States of America Medium 40924449
2026 MS4A4A regulates macrophage M2 polarization through NF-κB and JAK-STAT6 signaling pathways; macrophages overexpressing MS4A4A promote glioma cell proliferation, invasion, and temozolomide resistance in vitro and in vivo; targeting the MS4A4A/NF-κB/STAT6 axis improves outcomes in a glioma mouse model. MS4A4A knockdown and overexpression in macrophages, western blot for NF-κB and STAT6 pathway components, co-culture invasion/proliferation assays, in vivo subcutaneous and orthotopic glioma mouse models Oncogene Medium 42056558
2017 MS4A4A protein is localized to the plasma membrane in monocytes; it is expressed in M2 (IL-4-polarized) macrophages but not M1 (IFN-γ/LPS-activated) macrophages; it is induced during monocyte-to-macrophage differentiation and absent in immature/precursor myeloid cells and healthy B lymphocytes but present in plasma cells. Monoclonal antibody generation against extracellular epitopes, flow cytometry of human peripheral blood, in vitro monocyte differentiation assays Immunology and cell biology Medium 28303902

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2019 The macrophage tetraspan MS4A4A enhances dectin-1-dependent NK cell-mediated resistance to metastasis. Nature immunology 120 31263276
2023 Targeting MS4A4A on tumour-associated macrophages restores CD8+ T-cell-mediated antitumour immunity. Gut 114 37507218
2017 MS4A4A: a novel cell surface marker for M2 macrophages and plasma cells. Immunology and cell biology 79 28303902
2023 MS4A4A modifies the risk of Alzheimer disease by regulating lipid metabolism and immune response in a unique microglia state. medRxiv : the preprint server for health sciences 18 36798226
2020 The FcεRIβ homologue, MS4A4A, promotes FcεRI signal transduction and store-operated Ca2+ entry in human mast cells. Cellular signalling 17 32240745
2024 Targeting MS4A4A: A novel pathway to improve immunotherapy responses in glioblastoma. CNS neuroscience & therapeutics 15 38997808
2020 MS4A4A Regulates Arginase 1 Induction during Macrophage Polarization and Lung Inflammation in Mice. European journal of immunology 15 32589266
2025 Microglial MS4A4A Protects against Epileptic Seizures in Alzheimer's Disease. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 5 40349168
2025 The Alzheimer's disease risk genes MS4A4A and MS4A6A cooperate to negatively regulate TREM2 and microglia states. Neuron 4 41435829
2025 Ms4a4a deficiency ameliorates plaque pathology in a mouse model of amyloid accumulation. Alzheimer's & dementia : the journal of the Alzheimer's Association 3 40843775
2025 Synovial MS4A4A correlates with inflammation and counteracts response to corticosteroids in arthritis. Proceedings of the National Academy of Sciences of the United States of America 2 40924449
2026 Expression of MS4A4A on synovial infiltrating macrophages is a hallmark of rheumatoid arthritis and reflects disease severity. Immunological medicine 0 41955527
2026 MS4A4A promotes macrophages M2 polarization via NF-κB /JAK-STAT6 axis, resulting GBM malignant progression. Oncogene 0 42056558

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