{"gene":"CD37","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":1988,"finding":"CD37 (gp40-52) is a single-chain protein with ~25 kDa core bearing two N-linked complex carbohydrate chains (comprising ~50% of total molecular mass); it localizes both at the cell surface and in association with intracellular vesicles, as determined by biochemical fractionation and electron microscopy.","method":"Biochemical analysis (glycosidase digestion, SDS-PAGE), electron microscopy, subcellular fractionation","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 — direct biochemical characterization with multiple orthogonal methods in a single rigorous study","pmids":["3257508"],"is_preprint":false},{"year":1989,"finding":"CD37 is a 244-amino acid protein lacking a conventional leader sequence, with an N-terminal cytoplasmic domain followed by four transmembrane segments (three in the first 110 residues) and a hydrophilic region containing three N-linked glycosylation sites, establishing it as a four-transmembrane-spanning (tetraspanin) protein.","method":"cDNA cloning and primary sequence analysis","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1 — primary structure determination from cDNA, foundational study","pmids":["2466944"],"is_preprint":false},{"year":1994,"finding":"CD37, CD53, TAPA-1, and R2/C33 tetraspanins co-precipitate with MHC class II (DR) antigens along with CD19 and CD21 from mild detergent lysates of B cells, forming large multicomponent membrane complexes.","method":"Co-immunoprecipitation and preclearing experiments from B-cell line and tonsillar B-cell lysates","journal":"Immunogenetics","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with multiple components, replicated across cell types; highly cited foundational paper","pmids":["8119731"],"is_preprint":false},{"year":2000,"finding":"CD37-deficient mice show impaired T-cell-dependent IgG1 antibody responses to antigens administered without adjuvant and to viral infections, demonstrating that CD37 is required for optimal T-cell–B-cell interactions under suboptimal costimulatory conditions.","method":"Targeted gene knockout (CD37-/- mice), humoral immune response assays, serum immunoglobulin quantification","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined humoral immune phenotype, replicated across multiple immunization conditions","pmids":["10891477"],"is_preprint":false},{"year":2004,"finding":"CD37 negatively regulates T-cell proliferation by dampening early TCR signaling; CD37-deficient T cells are hyperproliferative with enhanced early IL-2 production, and CD4/CD8-associated p56(Lck) kinase activity is increased in CD37-/- T cells. Cross-linking of CD37 on human T cells completely inhibits CD3-induced proliferation.","method":"CD37-/- mouse T-cell proliferation assays, IL-2 measurement, p56(Lck) kinase activity assay, CD37 cross-linking experiments","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — KO phenotype with specific biochemical readout (Lck activity) and functional validation via cross-linking, multiple orthogonal methods","pmids":["14978098"],"is_preprint":false},{"year":2007,"finding":"CD37 interacts with the C-type lectin pattern-recognition receptor dectin-1 on APC membranes; CD37 stabilizes dectin-1 at the cell surface by inhibiting its internalization, and CD37 deficiency causes a 10-fold increase in dectin-1-induced IL-6 production despite reduced surface dectin-1.","method":"Co-localization studies, CD37-/- macrophage analysis, CD37 transfection into macrophage cell line, cytokine measurement","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — KO + rescue by transfection + specific cytokine readout, multiple orthogonal methods","pmids":["17182550"],"is_preprint":false},{"year":2009,"finding":"CD37 inhibits IgA immune responses in vivo; CD37-/- mice show 15-fold elevated serum IgA and increased IgA+ plasma cells. Bone marrow chimera experiments showed B-cell-intrinsic CD37 deficiency drives increased IgA production. CD37 deficiency leads to high local IL-6 in germinal centers, and neutralizing IL-6 in vivo reverses the elevated IgA response.","method":"CD37-/- mice, bone marrow chimeras, serum IgA quantification, IL-6 neutralization in vivo, flow cytometry","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including rescue experiment, strong mechanistic pathway placement","pmids":["19282981"],"is_preprint":false},{"year":2009,"finding":"CD37 and CD151 differentially regulate dendritic cell function: CD37 controls peptide/MHC class II antigen presentation while CD151 regulates co-stimulation, as shown by hyper-stimulatory phenotypes in CD37-/- and CD151-/- DCs toward antigen-specific T cells.","method":"DC-T cell co-stimulation assays using CD37-/- and CD151-/- DCs, antigen presentation assays","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined T-cell stimulation phenotype, mechanistic differentiation between two tetraspanins","pmids":["19089816"],"is_preprint":false},{"year":2012,"finding":"Upon ligation, CD37 becomes tyrosine phosphorylated and associates with proximal signaling molecules. An N-terminal ITIM-like motif (Tyr) mediates SHP1-dependent apoptotic signaling, while a C-terminal ITAM motif (Tyr) counteracts death signals via PI3K-dependent survival signaling, demonstrating CD37 directly transduces both death and survival signals.","method":"Site-directed mutagenesis of tyrosine residues, phosphoprotein assays, SHP1 co-immunoprecipitation, PI3K pathway analysis, apoptosis assays","journal":"Cancer cell","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis of specific residues with functional readout, multiple orthogonal biochemical methods in a single rigorous study","pmids":["22624718"],"is_preprint":false},{"year":2012,"finding":"CD37 is essential for α4β1 integrin-mediated Akt survival signaling in IgG-secreting plasma cells; CD37 regulates the mobility and clustering of α4β1 integrins in the plasma membrane, and CD37-/- plasma cells show impaired VCAM-1/α4β1-dependent Akt activation and increased apoptosis in germinal centers.","method":"CD37-/- mice, plasma cell survival assays, integrin clustering by imaging, Akt phosphorylation assays, VCAM-1 binding experiments","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 2 — KO with defined molecular mechanism (integrin clustering, Akt signaling), multiple orthogonal methods","pmids":["23150881"],"is_preprint":false},{"year":2013,"finding":"CD37 promotes dendritic cell migration from skin to draining lymph nodes, chemotactic migration, integrin-mediated adhesion under flow, cell spreading and actin protrusion formation. CD37-/- mice fail to induce antigen-specific IFN-γ-secreting T cells after intradermal challenge, demonstrating CD37 is required for cellular immunity via DC migration.","method":"CD37-/- mouse in vivo tumor challenge, intravital multiphoton microscopy of DC migration, in vitro chemotaxis assays, flow chamber adhesion assays","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — KO with in vivo and in vitro migration phenotype, live imaging, multiple orthogonal methods","pmids":["23420539"],"is_preprint":false},{"year":2015,"finding":"CD37 regulates β2 integrin-mediated neutrophil adhesion and recruitment; CD37-/- neutrophils show impaired ICAM-1 adhesion, reduced actin polymerization, impaired cell spreading and polarization, dysregulated Rac-1 activation, and accelerated β2 integrin internalization. Superresolution microscopy showed CD37 and CD18 do not significantly co-cluster, suggesting CD37 acts downstream of integrin-mediated adhesion via cytoskeletal regulation.","method":"CD37-/- mice, peritonitis model, intravital microscopy, flow chamber adhesion assays, superresolution microscopy, Rac-1 activation assays, actin polymerization assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — KO with in vivo and in vitro phenotype, superresolution imaging, multiple orthogonal methods","pmids":["26566675"],"is_preprint":false},{"year":2016,"finding":"CD37 interacts with SOCS3 (suppressor of cytokine signaling 3); loss of CD37 drives constitutive activation of the IL-6 signaling pathway, leading to germinal center-derived B-cell lymphoma development. Double knockout of Cd37 and Il6 fully protected mice from lymphoma, placing CD37 as a tumor suppressor acting via SOCS3-dependent inhibition of IL-6 signaling.","method":"Co-immunoprecipitation (CD37-SOCS3 interaction), CD37-/- mouse lymphoma model, Cd37/Il6 double-knockout mice, lymphoma incidence analysis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus genetic epistasis (double KO rescue), mechanistic pathway placement, replicated in human patient data","pmids":["26784544"],"is_preprint":false},{"year":2016,"finding":"CD37 and CD82 have opposing roles in coordinating dendritic cell migration and antigen presentation; CD37 promotes Rac-1 activation and cell migration (CD37-/- BMDCs spread poorly on fibronectin), while CD82 is a negative regulator of RhoA. Both tetraspanins negatively regulate Cdc42. An unactivated DC is CD37(hi)CD82(lo) (highly motile, limited T-cell activation capacity), while a late-activated DC is CD37(lo)CD82(hi) (adapted for T-cell activation).","method":"CD37-/- and CD82-/- BMDC functional assays, small GTPase activation assays (Rac-1, RhoA, Cdc42), fibronectin spreading assays, T-cell stimulation assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — KO phenotype with specific GTPase molecular mechanism, multiple orthogonal methods","pmids":["26729805"],"is_preprint":false},{"year":2018,"finding":"CLEC-2-dependent dendritic cell migration is controlled by CD37; CD37 specifically interacts with CLEC-2, and CD37-deficient DCs express reduced surface CLEC-2. Cd37-/- DCs show impaired adhesion, migration velocity and displacement on lymph node stromal cells, failure to form actin protrusions upon podoplanin-induced CLEC-2 stimulation, and CD37 is required for CLEC-2 recruitment to its ligand podoplanin in the membrane.","method":"Co-immunoprecipitation (CLEC-2/CD37 interaction), CD37-/- DC migration assays, 3D collagen matrix assays, microcontact printing, surface CLEC-2 quantification","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus KO functional phenotype with multiple migration readouts","pmids":["30185523"],"is_preprint":false},{"year":2018,"finding":"IL-6 is essential for glomerular IgA deposition and renal pathology in CD37-deficient mice; Cd37/Il6 double-knockout mice are fully protected from glomerular IgA deposition and accelerated renal failure, establishing CD37 inhibition of the IL-6 pathway as the mechanism protecting against IgA nephropathy.","method":"Cd37-/-, Il6-/-, and Cd37xIl6 double-knockout mice, renal histopathology, IgA quantification, IL-6 serum measurement","journal":"Kidney international","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis via double KO rescue, multiple readouts","pmids":["29551516"],"is_preprint":false},{"year":2022,"finding":"CD37 inhibits fatty acid (FA) metabolism in B-cell lymphoma by directly interacting with the fatty acid transporter FATP1; deletion of CD37 increases FA oxidation and uptake of exogenous palmitate. Inhibition of FATP1 reverses the metabolic phenotype of CD37-deficient lymphoma cells.","method":"Functional FA oxidation assays, metabolomics, co-immunoprecipitation (CD37-FATP1), FATP1 inhibition experiments, in vivo mouse studies, patient tissue analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1/2 — Co-IP identifying direct molecular interaction, functional assays, inhibitor rescue, multiple orthogonal methods","pmids":["36100608"],"is_preprint":false},{"year":2022,"finding":"IRF8 is a transcriptional activator of CD37 gene expression in DLBCL; IRF8 directly binds the CD37 promoter region (confirmed by DNA pulldown/mass spectrometry and ChIP), and IRF8 overexpression enhances CD37 protein levels while CRISPR/Cas9 knockout of IRF8 decreases CD37 expression.","method":"Quantitative nuclear proteomics, DNA pulldown + mass spectrometry, ChIP, IRF8 overexpression, CRISPR/Cas9 IRF8 knockout, immunohistochemistry","journal":"Blood advances","confidence":"High","confidence_rationale":"Tier 1/2 — direct promoter binding confirmed by ChIP and pulldown/MS, gain- and loss-of-function experiments","pmids":["35086136"],"is_preprint":false},{"year":2023,"finding":"N-glycosylation of CD37 is required for its surface expression; abrogation of CD37 glycosylation reduces surface CD37 levels. CD37 interaction with partner proteins CD53 and CD20 is affected by glycosylation in a localization-dependent manner, while its interaction with IL-6Rα is glycosylation-independent.","method":"Glycosylation mutant generation, flow cytometry, single-molecule dSTORM super-resolution microscopy, co-immunoprecipitation","journal":"Biophysical journal","confidence":"High","confidence_rationale":"Tier 1/2 — mutagenesis with functional readout, super-resolution imaging, multiple partner protein interactions tested","pmids":["38031400"],"is_preprint":false},{"year":2024,"finding":"CD20 and CD37 form a complex in the B-cell membrane; CD20 stabilizes CD37 at the cell surface. CD20 knockout results in downregulation of CD37, increased internalization of anti-CD37 mAb, and reduced complement-dependent cytotoxicity that can be partially restored by lysosome inhibition.","method":"CD20 knockout cell lines, co-immunoprecipitation (CD20/CD37 complex), flow cytometry, internalization assays, CDC assays","journal":"Oncoimmunology","confidence":"High","confidence_rationale":"Tier 2 — Co-IP identifying complex + KO functional phenotype, multiple orthogonal methods","pmids":["38846084"],"is_preprint":false},{"year":2024,"finding":"CD37 is a BCR-proximal protein; CRISPR-based knockout of CD37 in a B-cell line heightens BCR signaling, slows BCR endocytosis, and tempers formation of peptide-MHC class II complexes, demonstrating CD37 modulates membrane-mediated BCR functions.","method":"Proximity-based biotinylation (BioID) + mass spectrometry, CRISPR/Cas9 CD37 knockout, BCR signaling assays, BCR endocytosis assays, MHC class II antigen presentation assay","journal":"ImmunoHorizons","confidence":"High","confidence_rationale":"Tier 1/2 — proximity proteomics identifying interaction, CRISPR KO with multiple defined functional readouts","pmids":["38625120"],"is_preprint":false},{"year":2025,"finding":"CD37 interacts with integrin α4β7 and activates the PI3K-AKT pathway mediated by integrin signaling in AML leukemic stem cells; CD37 deficiency impairs LSC self-renewal, colony formation, and leukemia maintenance in vivo without affecting normal hematopoiesis.","method":"Co-immunoprecipitation (CD37/integrin α4β7), CD37 knockdown/KO in AML cell lines and mouse models, AKT phosphorylation assays, serial transplantation assays","journal":"Stem cell reports","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus in vivo KO with defined molecular mechanism (PI3K-AKT pathway)","pmids":["40250439"],"is_preprint":false},{"year":2025,"finding":"Tumor-derived macrophage migration inhibitory factor (MIF) directly binds to CD37, promoting phosphorylation of CD37 at Y13, recruiting SHP1, and inhibiting AKT signaling, thereby impairing macrophage phagocytosis. Targeting CD37 with an antibody promotes phagocytosis of multiple cancer cell types.","method":"Direct binding assays (MIF-CD37), phosphorylation site identification (CD37 Y13), SHP1 recruitment assay, AKT signaling assay, in vitro phagocytosis assays, in vivo tumor clearance models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1/2 — direct binding + phosphorylation site + downstream signaling cascade identified with multiple orthogonal methods","pmids":["40675974"],"is_preprint":false},{"year":2025,"finding":"DuoHexaBody-CD37 (biparatopic anti-CD37 antibody) induces significant CD37 clustering at the cell surface (without internalization), upregulates p-SHP1(Y564) in DLBCL cells (while primary B cells show increased p-AKT and MAPK survival signaling), and inhibits cytokine pro-survival signaling in DLBCL. The CD37 N-terminus is required for DuoHexaBody-CD37-induced signaling.","method":"CD37 clustering imaging, phosphoproteomic screen (26 phosphoproteins), CD37 N-terminus mutants, SHP1/AKT/MAPK pathway analysis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — unbiased phosphoproteomics + mutagenesis, but preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.02.24.639899"],"is_preprint":true},{"year":2025,"finding":"CD37 positively regulates platelet activation and thrombosis; Cd37-/- platelets exhibit impaired integrin αIIbβ3 signaling (reduced fibrinogen spreading and decreased agonist-induced αIIbβ3 activation), and Cd37-/- bone marrow chimeric mice show significantly increased time to vessel occlusion in a carotid artery FeCl3 thrombosis model.","method":"Cd37-/- mice, bone marrow chimera thrombosis model (carotid FeCl3), platelet αIIbβ3 activation assays, fibrinogen spreading assays, RNA-sequencing","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 2 — KO with in vivo thrombosis model and defined integrin signaling readout, bone marrow chimera confirms cell-intrinsic mechanism","pmids":["40126944"],"is_preprint":false}],"current_model":"CD37 is a tetraspanin membrane-organizing protein that directly transduces signals through ITIM-like and ITAM motifs (undergoing tyrosine phosphorylation to recruit SHP1 for apoptosis and PI3K for survival), organizes membrane partners including MHC class II, integrins (α4β1, α4β7, αIIbβ3, β2), dectin-1, CLEC-2, FATP1, CD20, and the BCR complex, regulates B-cell IgA and IgG responses through IL-6/SOCS3 pathway control, promotes DC and neutrophil migration via Rac-1-dependent cytoskeletal regulation, and acts as a tumor suppressor in B cells by restraining constitutive IL-6 signaling and as a gatekeeper of fatty acid metabolism through direct inhibition of FATP1."},"narrative":{"teleology":[{"year":1989,"claim":"Establishing CD37 as a tetraspanin resolved the fundamental question of its membrane topology, revealing four transmembrane domains with short cytoplasmic tails and an extracellular loop bearing N-linked glycosylation sites.","evidence":"cDNA cloning and primary sequence analysis of the 244-amino acid protein","pmids":["2466944"],"confidence":"High","gaps":["No information on post-translational modifications beyond glycosylation","Functional role of the short cytoplasmic domains unknown"]},{"year":1994,"claim":"Demonstrating that CD37 co-precipitates with MHC class II, CD19, and other tetraspanins established that it participates in large multicomponent membrane complexes on B cells, raising the question of its organizing function.","evidence":"Co-immunoprecipitation and preclearing experiments from B-cell lines and tonsillar B cells","pmids":["8119731"],"confidence":"High","gaps":["Whether CD37 directly contacts MHC II or interacts indirectly through tetraspanin networks","Functional consequence of complex formation unknown"]},{"year":2000,"claim":"The first CD37 knockout mice revealed impaired T-cell-dependent IgG1 responses, establishing a non-redundant role for CD37 in humoral immunity and T–B cell cooperation.","evidence":"Cd37−/− mice immunized with T-dependent antigens with and without adjuvant, serum Ig quantification","pmids":["10891477"],"confidence":"High","gaps":["Molecular mechanism by which CD37 supports T–B interaction undefined","Whether the defect is B-cell- or T-cell-intrinsic unresolved"]},{"year":2004,"claim":"Showing that CD37 deficiency causes T-cell hyperproliferation with enhanced Lck kinase activity, and that CD37 cross-linking inhibits TCR-driven proliferation, revealed CD37 as a negative regulator of proximal TCR signaling.","evidence":"Cd37−/− T-cell proliferation assays, Lck activity measurement, CD37 cross-linking on human T cells","pmids":["14978098"],"confidence":"High","gaps":["Direct physical connection between CD37 and the TCR/Lck complex not shown","Mechanism of Lck suppression unknown"]},{"year":2007,"claim":"Identification of dectin-1 as a CD37 partner on APCs, where CD37 stabilizes dectin-1 surface expression and restrains dectin-1-induced IL-6 production, provided the first evidence that CD37 negatively controls innate immune cytokine output.","evidence":"Co-localization, Cd37−/− macrophage cytokine assays, rescue by CD37 transfection","pmids":["17182550"],"confidence":"High","gaps":["Mechanism of dectin-1 internalization control by CD37 not defined","Whether CD37-dectin-1 interaction is direct or within tetraspanin web unclear"]},{"year":2009,"claim":"Demonstrating that CD37 loss causes 15-fold elevated IgA via B-cell-intrinsic IL-6 overproduction—reversible by IL-6 neutralization—identified the CD37/IL-6 axis as a master regulator of IgA class switching, linking CD37 to IgA nephropathy pathogenesis.","evidence":"Cd37−/− mice, bone marrow chimeras, IL-6 neutralization in vivo, serum IgA quantification","pmids":["19282981"],"confidence":"High","gaps":["How CD37 restrains IL-6 at the molecular level not yet identified","Relevance to human IgA nephropathy not directly tested"]},{"year":2012,"claim":"Mapping ITIM-like (N-terminal Tyr → SHP1 → apoptosis) and ITAM (C-terminal Tyr → PI3K → survival) motifs on CD37 established it as a direct signal transducer, not merely a membrane organizer, resolving a long-standing question about tetraspanin signaling competence.","evidence":"Site-directed mutagenesis of tyrosine residues, SHP1 Co-IP, PI3K pathway analysis, apoptosis assays","pmids":["22624718"],"confidence":"High","gaps":["Identity of the kinase(s) that phosphorylate CD37 tyrosines unknown","Whether both motifs are simultaneously active in the same cell context unclear"]},{"year":2012,"claim":"Showing that CD37 controls α4β1 integrin clustering and VCAM-1-dependent Akt activation in plasma cells linked the tetraspanin membrane-organizing function to integrin-mediated survival signaling in germinal centers.","evidence":"Cd37−/− mice, integrin clustering imaging, Akt phosphorylation, VCAM-1 binding assays","pmids":["23150881"],"confidence":"High","gaps":["Whether CD37 directly binds α4β1 or acts through lateral tetraspanin interactions not resolved","Structural basis of integrin clustering by CD37 unknown"]},{"year":2013,"claim":"Demonstrating that CD37 is required for DC migration from skin to lymph nodes, chemotaxis, and integrin-mediated adhesion under flow established CD37 as essential for cellular immunity beyond humoral responses.","evidence":"Cd37−/− mice, intravital multiphoton imaging, in vitro chemotaxis and flow chamber assays","pmids":["23420539"],"confidence":"High","gaps":["Specific integrin(s) organized by CD37 during DC migration not identified","Downstream cytoskeletal effector undefined at this stage"]},{"year":2015,"claim":"Identifying dysregulated Rac-1 activation and accelerated β2 integrin internalization in CD37-deficient neutrophils established a cytoskeletal mechanism—Rac-1-dependent actin polymerization—for CD37's role in leukocyte adhesion and migration.","evidence":"Cd37−/− neutrophils, peritonitis model, intravital microscopy, superresolution microscopy, Rac-1 activation assays","pmids":["26566675"],"confidence":"High","gaps":["How CD37 activates Rac-1 (direct or via GEF recruitment) unknown","Superresolution showed CD37 and CD18 do not co-cluster, so the spatial mechanism of action remains unclear"]},{"year":2016,"claim":"Identification of SOCS3 as a CD37 interaction partner, combined with genetic epistasis showing that IL-6 deletion rescues CD37−/− lymphomagenesis, established CD37 as a tumor suppressor acting through SOCS3-dependent restraint of constitutive IL-6 signaling.","evidence":"Co-IP (CD37–SOCS3), Cd37−/− lymphoma model, Cd37/Il6 double-knockout rescue","pmids":["26784544"],"confidence":"High","gaps":["Whether CD37 stabilizes SOCS3 protein levels or recruits it to IL-6 receptor complexes not distinguished","Applicability to human DLBCL treatment not functionally tested"]},{"year":2018,"claim":"Genetic epistasis confirmed that IL-6 is the causative mediator of IgA nephropathy in CD37-deficient mice, as Cd37/Il6 double knockouts were fully protected from glomerular IgA deposition and renal failure.","evidence":"Cd37/Il6 double-knockout mice, renal histopathology, IgA and IL-6 quantification","pmids":["29551516"],"confidence":"High","gaps":["Translational relevance to human IgA nephropathy not validated","Whether therapeutic IL-6 blockade recapitulates the protective effect untested"]},{"year":2018,"claim":"Showing that CD37 directly interacts with CLEC-2 and is required for CLEC-2-dependent DC migration and actin protrusion formation upon podoplanin stimulation extended CD37's organizing function to C-type lectin receptor–mediated migration.","evidence":"Co-IP (CLEC-2/CD37), Cd37−/− DC migration in 3D collagen matrices, microcontact printing","pmids":["30185523"],"confidence":"High","gaps":["Whether CD37 controls CLEC-2 signaling beyond surface stabilization unknown","Role in lymph node architecture in vivo not fully characterized"]},{"year":2022,"claim":"Discovery that CD37 directly binds FATP1 and inhibits fatty acid uptake and oxidation in B-cell lymphoma expanded CD37's functional repertoire to metabolic regulation, with FATP1 inhibition reversing the metabolic phenotype of CD37-deficient cells.","evidence":"Co-IP (CD37–FATP1), FA oxidation assays, metabolomics, FATP1 inhibitor rescue, in vivo mouse studies","pmids":["36100608"],"confidence":"High","gaps":["Structural basis of CD37–FATP1 interaction unknown","Whether metabolic control contributes to CD37's tumor suppressor function independently of IL-6 pathway not established"]},{"year":2022,"claim":"Identifying IRF8 as a direct transcriptional activator of CD37 via promoter binding addressed the upstream regulation of CD37 expression, providing a mechanistic basis for CD37 loss in DLBCL lacking IRF8.","evidence":"DNA pulldown/mass spectrometry, ChIP, IRF8 overexpression, CRISPR/Cas9 IRF8 knockout in DLBCL","pmids":["35086136"],"confidence":"High","gaps":["Other transcription factors regulating CD37 not explored","Whether IRF8 loss explains CD37 downregulation across all lymphoma subtypes unknown"]},{"year":2023,"claim":"Mutagenesis of N-glycosylation sites showed glycosylation is required for CD37 surface expression and modulates partner interactions (CD53, CD20) in a localization-dependent manner, while IL-6Rα interaction is glycosylation-independent.","evidence":"Glycosylation mutants, flow cytometry, single-molecule dSTORM super-resolution microscopy, Co-IP","pmids":["38031400"],"confidence":"High","gaps":["Which specific glycan structures are functionally important not defined","Impact of glycosylation on CD37 signaling through ITIM/ITAM motifs not tested"]},{"year":2024,"claim":"Demonstrating that CD20 forms a complex with CD37 and stabilizes its surface expression—with CD20 knockout causing CD37 downregulation and increased internalization—revealed reciprocal stabilization within the tetraspanin network relevant to antibody therapy.","evidence":"CD20 KO cell lines, Co-IP (CD20/CD37), internalization assays, CDC assays","pmids":["38846084"],"confidence":"High","gaps":["Whether CD37 reciprocally stabilizes CD20 not tested","Implications for sequential anti-CD20/anti-CD37 therapy not clinically validated"]},{"year":2024,"claim":"Proximity proteomics identified CD37 as a BCR-proximal protein; CD37 knockout heightened BCR signaling, slowed BCR endocytosis, and reduced pMHC-II formation, establishing CD37 as a modulator of antigen processing via BCR dynamics.","evidence":"BioID proximity labeling + mass spectrometry, CRISPR CD37 KO, BCR signaling and endocytosis assays, MHC II antigen presentation assay","pmids":["38625120"],"confidence":"High","gaps":["Direct physical contact between CD37 and specific BCR subunits not confirmed by reciprocal IP","Whether CD37's effect on BCR is through lateral membrane organization or direct binding not resolved"]},{"year":2025,"claim":"Extension of CD37's integrin-organizing function to platelets (αIIbβ3) and AML leukemic stem cells (α4β7/PI3K-AKT) demonstrated tissue-broad roles in integrin signaling, thrombosis regulation, and leukemia maintenance.","evidence":"Cd37−/− platelet assays, FeCl3 carotid thrombosis model, bone marrow chimeras; Co-IP (CD37/α4β7), AML serial transplantation in Cd37 KO mice","pmids":["40126944","40250439"],"confidence":"High","gaps":["Structural interface between CD37 and different integrins not characterized","Whether CD37-integrin interactions are direct or mediated by other tetraspanins not resolved for all integrin partners"]},{"year":2025,"claim":"Identification of tumor-derived MIF as an extrinsic CD37 ligand that triggers Y13 phosphorylation, SHP1 recruitment, and AKT inhibition in macrophages revealed a tumor immune evasion mechanism operating through CD37's ITIM-like motif.","evidence":"Direct MIF-CD37 binding assays, Y13 phosphorylation identification, SHP1/AKT signaling, in vitro phagocytosis and in vivo tumor models","pmids":["40675974"],"confidence":"High","gaps":["Whether MIF binding to CD37 occurs in physiological non-tumor contexts unknown","Crystal structure of MIF-CD37 interaction not available"]},{"year":null,"claim":"The identity of the kinase(s) phosphorylating CD37 ITIM-like and ITAM tyrosines, the structural basis of CD37–integrin and CD37–FATP1 interactions, and whether CD37's metabolic and IL-6-restraining tumor suppressor functions operate independently or synergistically remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No kinase identified for CD37 tyrosine phosphorylation","No atomic-resolution structure of CD37 or its complexes","Relative contribution of metabolic vs. IL-6 pathway control to tumor suppression not dissected"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,5,9,14,19,20]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[8,22]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,12,16]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,9,18,19]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,4,5,6,7,10,11,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,9,12,21,22]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[8,22]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[16]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[24]}],"complexes":["Tetraspanin-enriched microdomain (TEM)","CD20-CD37 complex"],"partners":["SHP1","SOCS3","CLEC2","FATP1","CD20","ITGA4","ITGB1","MIF"],"other_free_text":[]},"mechanistic_narrative":"CD37 is a tetraspanin that organizes membrane signaling complexes on leukocytes, coupling receptor compartmentalization to intracellular signal transduction, integrin function, cytoskeletal dynamics, and metabolic control. Upon ligation, CD37 undergoes tyrosine phosphorylation at N-terminal ITIM-like and C-terminal ITAM motifs, recruiting SHP1 to initiate apoptotic signaling or PI3K to promote survival, respectively [PMID:22624718, PMID:40675974]. CD37 restrains IL-6 signaling through interaction with SOCS3, thereby suppressing germinal center–derived B-cell lymphomagenesis and preventing IgA nephropathy; genetic ablation of IL-6 fully rescues both pathologies in CD37-deficient mice [PMID:26784544, PMID:29551516, PMID:19282981]. CD37 also organizes integrins (α4β1, α4β7, αIIbβ3, β2), the BCR complex, dectin-1, CLEC-2, CD20, and FATP1 at the cell surface, regulating integrin-dependent adhesion and Akt survival signaling, Rac-1-dependent dendritic cell and neutrophil migration, BCR endocytosis and MHC class II antigen presentation, platelet activation, and fatty acid uptake [PMID:23150881, PMID:40250439, PMID:40126944, PMID:26566675, PMID:30185523, PMID:38625120, PMID:36100608]."},"prefetch_data":{"uniprot":{"accession":"P11049","full_name":"Leukocyte antigen CD37","aliases":["Tetraspanin-26","Tspan-26"],"length_aa":281,"mass_kda":31.7,"function":"Structural component of specialized membrane microdomains known as tetraspanin-enriched microdomains (TERMs), which act as platforms for receptor clustering and signaling. Participates thereby in diverse biological functions such as cell signal transduction, adhesion, migration and protein trafficking (PubMed:22624718). Upon ligand binding, two signaling pathways are activated, one acting through phosphorylation by LYN leading to cell death or a survival pathway with activation of GSK3B (PubMed:22624718). Plays an essential role essential for clustering of integrin ITGA4/ITGB1 and promotes its mobility in the plasma membrane of B-cells. In turn, participates in ITGA4/ITGB1 integrin-mediated antiapoptotic signaling through AKT (By similarity). Also plays a role in the migration of dendritic cells and neutrophils to draining lymph nodes, as well as in their integrin-mediated adhesion (By similarity). Negatively regulates IL-6 responses through direct interaction with SOCS3 thereby preventing constitutive IL-6 signaling (PubMed:26784544). 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targeting of CD37-positive lymphomas with the antibody-drug conjugate naratuximab emtansine.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38014209","citation_count":4,"is_preprint":false},{"pmid":"40126944","id":"PMC_40126944","title":"Tetraspanin CD37 regulates platelet hyperreactivity and thrombosis.","date":"2025","source":"Cardiovascular research","url":"https://pubmed.ncbi.nlm.nih.gov/40126944","citation_count":3,"is_preprint":false},{"pmid":"40739330","id":"PMC_40739330","title":"Combining MCL-1 inhibition and CD37-directed chimeric antigen receptor T cells as an effective strategy to target T-cell lymphoma.","date":"2025","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/40739330","citation_count":3,"is_preprint":false},{"pmid":"24235129","id":"PMC_24235129","title":"In the spotlight: a novel CD37 antibody-drug conjugate.","date":"2013","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/24235129","citation_count":3,"is_preprint":false},{"pmid":"35486574","id":"PMC_35486574","title":"Anti-CD37 radioimmunotherapy with 177Lu-NNV003 synergizes with the PARP inhibitor olaparib in treatment of non-Hodgkin's lymphoma in vitro.","date":"2022","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/35486574","citation_count":3,"is_preprint":false},{"pmid":"40675974","id":"PMC_40675974","title":"Targeting CD37 promotes macrophage-dependent phagocytosis of multiple cancer cell types and facilitates tumor clearance in mice.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40675974","citation_count":2,"is_preprint":false},{"pmid":"24989269","id":"PMC_24989269","title":"[Significance of CD37 expression in malignant B cells].","date":"2014","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/24989269","citation_count":2,"is_preprint":false},{"pmid":"37274903","id":"PMC_37274903","title":"The Impact of CD37 Ectoenzyme Expression in Benign and Malignant Colorectal Tumors.","date":"2022","source":"Archives of Razi Institute","url":"https://pubmed.ncbi.nlm.nih.gov/37274903","citation_count":1,"is_preprint":false},{"pmid":"40250439","id":"PMC_40250439","title":"CD37 regulates the self-renewal of leukemic stem cells via integrin-mediated signaling in acute myeloid leukemia.","date":"2025","source":"Stem cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/40250439","citation_count":1,"is_preprint":false},{"pmid":"38625120","id":"PMC_38625120","title":"Proximity-Based Labeling Identifies MHC Class II and CD37 as B Cell Receptor-Proximal Proteins with Immunological Functions.","date":"2024","source":"ImmunoHorizons","url":"https://pubmed.ncbi.nlm.nih.gov/38625120","citation_count":1,"is_preprint":false},{"pmid":"42013843","id":"PMC_42013843","title":"Debio 1562M CD37-targeting ADC is highly active and well tolerated in preclinical models of AML and MDS.","date":"2026","source":"Cell reports. Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/42013843","citation_count":0,"is_preprint":false},{"pmid":"41754790","id":"PMC_41754790","title":"A Phase II Study of 177Lu-Lilotomab Satetraxetan, a CD37 Antibody-Radionuclide Conjugate, as Third- or Later-Line Treatment of Rituximab-Refractory Follicular B-Cell Lymphoma Patients.","date":"2026","source":"Pharmaceuticals (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/41754790","citation_count":0,"is_preprint":false},{"pmid":"40543727","id":"PMC_40543727","title":"Reduced CD37 expression in B cell subsets after stimulation and its clinical relevance in primary Sjögren's syndrome.","date":"2025","source":"Immunology letters","url":"https://pubmed.ncbi.nlm.nih.gov/40543727","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.05.30.596390","title":"Comprehensive Analysis of<sup>177</sup>Lu-lilotomab Satetraxetan in Lymphoma Cell Lines: Implications for Precision Radioimmunotherapy and Combination Schemes","date":"2024-06-03","source":"bioRxiv","url":"https://doi.org/10.1101/2024.05.30.596390","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.02.24.639899","title":"DuoHexaBody-CD37 induces direct cytotoxic signaling in diffuse large B-cell lymphoma","date":"2025-02-28","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.24.639899","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":48205,"output_tokens":6133,"usd":0.118305},"stage2":{"model":"claude-opus-4-6","input_tokens":9793,"output_tokens":4778,"usd":0.252623},"total_usd":0.370928,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1988,\n      \"finding\": \"CD37 (gp40-52) is a single-chain protein with ~25 kDa core bearing two N-linked complex carbohydrate chains (comprising ~50% of total molecular mass); it localizes both at the cell surface and in association with intracellular vesicles, as determined by biochemical fractionation and electron microscopy.\",\n      \"method\": \"Biochemical analysis (glycosidase digestion, SDS-PAGE), electron microscopy, subcellular fractionation\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct biochemical characterization with multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"3257508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1989,\n      \"finding\": \"CD37 is a 244-amino acid protein lacking a conventional leader sequence, with an N-terminal cytoplasmic domain followed by four transmembrane segments (three in the first 110 residues) and a hydrophilic region containing three N-linked glycosylation sites, establishing it as a four-transmembrane-spanning (tetraspanin) protein.\",\n      \"method\": \"cDNA cloning and primary sequence analysis\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — primary structure determination from cDNA, foundational study\",\n      \"pmids\": [\"2466944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"CD37, CD53, TAPA-1, and R2/C33 tetraspanins co-precipitate with MHC class II (DR) antigens along with CD19 and CD21 from mild detergent lysates of B cells, forming large multicomponent membrane complexes.\",\n      \"method\": \"Co-immunoprecipitation and preclearing experiments from B-cell line and tonsillar B-cell lysates\",\n      \"journal\": \"Immunogenetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with multiple components, replicated across cell types; highly cited foundational paper\",\n      \"pmids\": [\"8119731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CD37-deficient mice show impaired T-cell-dependent IgG1 antibody responses to antigens administered without adjuvant and to viral infections, demonstrating that CD37 is required for optimal T-cell–B-cell interactions under suboptimal costimulatory conditions.\",\n      \"method\": \"Targeted gene knockout (CD37-/- mice), humoral immune response assays, serum immunoglobulin quantification\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined humoral immune phenotype, replicated across multiple immunization conditions\",\n      \"pmids\": [\"10891477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CD37 negatively regulates T-cell proliferation by dampening early TCR signaling; CD37-deficient T cells are hyperproliferative with enhanced early IL-2 production, and CD4/CD8-associated p56(Lck) kinase activity is increased in CD37-/- T cells. Cross-linking of CD37 on human T cells completely inhibits CD3-induced proliferation.\",\n      \"method\": \"CD37-/- mouse T-cell proliferation assays, IL-2 measurement, p56(Lck) kinase activity assay, CD37 cross-linking experiments\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO phenotype with specific biochemical readout (Lck activity) and functional validation via cross-linking, multiple orthogonal methods\",\n      \"pmids\": [\"14978098\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CD37 interacts with the C-type lectin pattern-recognition receptor dectin-1 on APC membranes; CD37 stabilizes dectin-1 at the cell surface by inhibiting its internalization, and CD37 deficiency causes a 10-fold increase in dectin-1-induced IL-6 production despite reduced surface dectin-1.\",\n      \"method\": \"Co-localization studies, CD37-/- macrophage analysis, CD37 transfection into macrophage cell line, cytokine measurement\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO + rescue by transfection + specific cytokine readout, multiple orthogonal methods\",\n      \"pmids\": [\"17182550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CD37 inhibits IgA immune responses in vivo; CD37-/- mice show 15-fold elevated serum IgA and increased IgA+ plasma cells. Bone marrow chimera experiments showed B-cell-intrinsic CD37 deficiency drives increased IgA production. CD37 deficiency leads to high local IL-6 in germinal centers, and neutralizing IL-6 in vivo reverses the elevated IgA response.\",\n      \"method\": \"CD37-/- mice, bone marrow chimeras, serum IgA quantification, IL-6 neutralization in vivo, flow cytometry\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including rescue experiment, strong mechanistic pathway placement\",\n      \"pmids\": [\"19282981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CD37 and CD151 differentially regulate dendritic cell function: CD37 controls peptide/MHC class II antigen presentation while CD151 regulates co-stimulation, as shown by hyper-stimulatory phenotypes in CD37-/- and CD151-/- DCs toward antigen-specific T cells.\",\n      \"method\": \"DC-T cell co-stimulation assays using CD37-/- and CD151-/- DCs, antigen presentation assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined T-cell stimulation phenotype, mechanistic differentiation between two tetraspanins\",\n      \"pmids\": [\"19089816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Upon ligation, CD37 becomes tyrosine phosphorylated and associates with proximal signaling molecules. An N-terminal ITIM-like motif (Tyr) mediates SHP1-dependent apoptotic signaling, while a C-terminal ITAM motif (Tyr) counteracts death signals via PI3K-dependent survival signaling, demonstrating CD37 directly transduces both death and survival signals.\",\n      \"method\": \"Site-directed mutagenesis of tyrosine residues, phosphoprotein assays, SHP1 co-immunoprecipitation, PI3K pathway analysis, apoptosis assays\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis of specific residues with functional readout, multiple orthogonal biochemical methods in a single rigorous study\",\n      \"pmids\": [\"22624718\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CD37 is essential for α4β1 integrin-mediated Akt survival signaling in IgG-secreting plasma cells; CD37 regulates the mobility and clustering of α4β1 integrins in the plasma membrane, and CD37-/- plasma cells show impaired VCAM-1/α4β1-dependent Akt activation and increased apoptosis in germinal centers.\",\n      \"method\": \"CD37-/- mice, plasma cell survival assays, integrin clustering by imaging, Akt phosphorylation assays, VCAM-1 binding experiments\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with defined molecular mechanism (integrin clustering, Akt signaling), multiple orthogonal methods\",\n      \"pmids\": [\"23150881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CD37 promotes dendritic cell migration from skin to draining lymph nodes, chemotactic migration, integrin-mediated adhesion under flow, cell spreading and actin protrusion formation. CD37-/- mice fail to induce antigen-specific IFN-γ-secreting T cells after intradermal challenge, demonstrating CD37 is required for cellular immunity via DC migration.\",\n      \"method\": \"CD37-/- mouse in vivo tumor challenge, intravital multiphoton microscopy of DC migration, in vitro chemotaxis assays, flow chamber adhesion assays\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with in vivo and in vitro migration phenotype, live imaging, multiple orthogonal methods\",\n      \"pmids\": [\"23420539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CD37 regulates β2 integrin-mediated neutrophil adhesion and recruitment; CD37-/- neutrophils show impaired ICAM-1 adhesion, reduced actin polymerization, impaired cell spreading and polarization, dysregulated Rac-1 activation, and accelerated β2 integrin internalization. Superresolution microscopy showed CD37 and CD18 do not significantly co-cluster, suggesting CD37 acts downstream of integrin-mediated adhesion via cytoskeletal regulation.\",\n      \"method\": \"CD37-/- mice, peritonitis model, intravital microscopy, flow chamber adhesion assays, superresolution microscopy, Rac-1 activation assays, actin polymerization assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with in vivo and in vitro phenotype, superresolution imaging, multiple orthogonal methods\",\n      \"pmids\": [\"26566675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CD37 interacts with SOCS3 (suppressor of cytokine signaling 3); loss of CD37 drives constitutive activation of the IL-6 signaling pathway, leading to germinal center-derived B-cell lymphoma development. Double knockout of Cd37 and Il6 fully protected mice from lymphoma, placing CD37 as a tumor suppressor acting via SOCS3-dependent inhibition of IL-6 signaling.\",\n      \"method\": \"Co-immunoprecipitation (CD37-SOCS3 interaction), CD37-/- mouse lymphoma model, Cd37/Il6 double-knockout mice, lymphoma incidence analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus genetic epistasis (double KO rescue), mechanistic pathway placement, replicated in human patient data\",\n      \"pmids\": [\"26784544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CD37 and CD82 have opposing roles in coordinating dendritic cell migration and antigen presentation; CD37 promotes Rac-1 activation and cell migration (CD37-/- BMDCs spread poorly on fibronectin), while CD82 is a negative regulator of RhoA. Both tetraspanins negatively regulate Cdc42. An unactivated DC is CD37(hi)CD82(lo) (highly motile, limited T-cell activation capacity), while a late-activated DC is CD37(lo)CD82(hi) (adapted for T-cell activation).\",\n      \"method\": \"CD37-/- and CD82-/- BMDC functional assays, small GTPase activation assays (Rac-1, RhoA, Cdc42), fibronectin spreading assays, T-cell stimulation assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO phenotype with specific GTPase molecular mechanism, multiple orthogonal methods\",\n      \"pmids\": [\"26729805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CLEC-2-dependent dendritic cell migration is controlled by CD37; CD37 specifically interacts with CLEC-2, and CD37-deficient DCs express reduced surface CLEC-2. Cd37-/- DCs show impaired adhesion, migration velocity and displacement on lymph node stromal cells, failure to form actin protrusions upon podoplanin-induced CLEC-2 stimulation, and CD37 is required for CLEC-2 recruitment to its ligand podoplanin in the membrane.\",\n      \"method\": \"Co-immunoprecipitation (CLEC-2/CD37 interaction), CD37-/- DC migration assays, 3D collagen matrix assays, microcontact printing, surface CLEC-2 quantification\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus KO functional phenotype with multiple migration readouts\",\n      \"pmids\": [\"30185523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IL-6 is essential for glomerular IgA deposition and renal pathology in CD37-deficient mice; Cd37/Il6 double-knockout mice are fully protected from glomerular IgA deposition and accelerated renal failure, establishing CD37 inhibition of the IL-6 pathway as the mechanism protecting against IgA nephropathy.\",\n      \"method\": \"Cd37-/-, Il6-/-, and Cd37xIl6 double-knockout mice, renal histopathology, IgA quantification, IL-6 serum measurement\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis via double KO rescue, multiple readouts\",\n      \"pmids\": [\"29551516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CD37 inhibits fatty acid (FA) metabolism in B-cell lymphoma by directly interacting with the fatty acid transporter FATP1; deletion of CD37 increases FA oxidation and uptake of exogenous palmitate. Inhibition of FATP1 reverses the metabolic phenotype of CD37-deficient lymphoma cells.\",\n      \"method\": \"Functional FA oxidation assays, metabolomics, co-immunoprecipitation (CD37-FATP1), FATP1 inhibition experiments, in vivo mouse studies, patient tissue analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — Co-IP identifying direct molecular interaction, functional assays, inhibitor rescue, multiple orthogonal methods\",\n      \"pmids\": [\"36100608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IRF8 is a transcriptional activator of CD37 gene expression in DLBCL; IRF8 directly binds the CD37 promoter region (confirmed by DNA pulldown/mass spectrometry and ChIP), and IRF8 overexpression enhances CD37 protein levels while CRISPR/Cas9 knockout of IRF8 decreases CD37 expression.\",\n      \"method\": \"Quantitative nuclear proteomics, DNA pulldown + mass spectrometry, ChIP, IRF8 overexpression, CRISPR/Cas9 IRF8 knockout, immunohistochemistry\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — direct promoter binding confirmed by ChIP and pulldown/MS, gain- and loss-of-function experiments\",\n      \"pmids\": [\"35086136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"N-glycosylation of CD37 is required for its surface expression; abrogation of CD37 glycosylation reduces surface CD37 levels. CD37 interaction with partner proteins CD53 and CD20 is affected by glycosylation in a localization-dependent manner, while its interaction with IL-6Rα is glycosylation-independent.\",\n      \"method\": \"Glycosylation mutant generation, flow cytometry, single-molecule dSTORM super-resolution microscopy, co-immunoprecipitation\",\n      \"journal\": \"Biophysical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — mutagenesis with functional readout, super-resolution imaging, multiple partner protein interactions tested\",\n      \"pmids\": [\"38031400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CD20 and CD37 form a complex in the B-cell membrane; CD20 stabilizes CD37 at the cell surface. CD20 knockout results in downregulation of CD37, increased internalization of anti-CD37 mAb, and reduced complement-dependent cytotoxicity that can be partially restored by lysosome inhibition.\",\n      \"method\": \"CD20 knockout cell lines, co-immunoprecipitation (CD20/CD37 complex), flow cytometry, internalization assays, CDC assays\",\n      \"journal\": \"Oncoimmunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP identifying complex + KO functional phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"38846084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CD37 is a BCR-proximal protein; CRISPR-based knockout of CD37 in a B-cell line heightens BCR signaling, slows BCR endocytosis, and tempers formation of peptide-MHC class II complexes, demonstrating CD37 modulates membrane-mediated BCR functions.\",\n      \"method\": \"Proximity-based biotinylation (BioID) + mass spectrometry, CRISPR/Cas9 CD37 knockout, BCR signaling assays, BCR endocytosis assays, MHC class II antigen presentation assay\",\n      \"journal\": \"ImmunoHorizons\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — proximity proteomics identifying interaction, CRISPR KO with multiple defined functional readouts\",\n      \"pmids\": [\"38625120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CD37 interacts with integrin α4β7 and activates the PI3K-AKT pathway mediated by integrin signaling in AML leukemic stem cells; CD37 deficiency impairs LSC self-renewal, colony formation, and leukemia maintenance in vivo without affecting normal hematopoiesis.\",\n      \"method\": \"Co-immunoprecipitation (CD37/integrin α4β7), CD37 knockdown/KO in AML cell lines and mouse models, AKT phosphorylation assays, serial transplantation assays\",\n      \"journal\": \"Stem cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus in vivo KO with defined molecular mechanism (PI3K-AKT pathway)\",\n      \"pmids\": [\"40250439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Tumor-derived macrophage migration inhibitory factor (MIF) directly binds to CD37, promoting phosphorylation of CD37 at Y13, recruiting SHP1, and inhibiting AKT signaling, thereby impairing macrophage phagocytosis. Targeting CD37 with an antibody promotes phagocytosis of multiple cancer cell types.\",\n      \"method\": \"Direct binding assays (MIF-CD37), phosphorylation site identification (CD37 Y13), SHP1 recruitment assay, AKT signaling assay, in vitro phagocytosis assays, in vivo tumor clearance models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — direct binding + phosphorylation site + downstream signaling cascade identified with multiple orthogonal methods\",\n      \"pmids\": [\"40675974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DuoHexaBody-CD37 (biparatopic anti-CD37 antibody) induces significant CD37 clustering at the cell surface (without internalization), upregulates p-SHP1(Y564) in DLBCL cells (while primary B cells show increased p-AKT and MAPK survival signaling), and inhibits cytokine pro-survival signaling in DLBCL. The CD37 N-terminus is required for DuoHexaBody-CD37-induced signaling.\",\n      \"method\": \"CD37 clustering imaging, phosphoproteomic screen (26 phosphoproteins), CD37 N-terminus mutants, SHP1/AKT/MAPK pathway analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — unbiased phosphoproteomics + mutagenesis, but preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.02.24.639899\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CD37 positively regulates platelet activation and thrombosis; Cd37-/- platelets exhibit impaired integrin αIIbβ3 signaling (reduced fibrinogen spreading and decreased agonist-induced αIIbβ3 activation), and Cd37-/- bone marrow chimeric mice show significantly increased time to vessel occlusion in a carotid artery FeCl3 thrombosis model.\",\n      \"method\": \"Cd37-/- mice, bone marrow chimera thrombosis model (carotid FeCl3), platelet αIIbβ3 activation assays, fibrinogen spreading assays, RNA-sequencing\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with in vivo thrombosis model and defined integrin signaling readout, bone marrow chimera confirms cell-intrinsic mechanism\",\n      \"pmids\": [\"40126944\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CD37 is a tetraspanin membrane-organizing protein that directly transduces signals through ITIM-like and ITAM motifs (undergoing tyrosine phosphorylation to recruit SHP1 for apoptosis and PI3K for survival), organizes membrane partners including MHC class II, integrins (α4β1, α4β7, αIIbβ3, β2), dectin-1, CLEC-2, FATP1, CD20, and the BCR complex, regulates B-cell IgA and IgG responses through IL-6/SOCS3 pathway control, promotes DC and neutrophil migration via Rac-1-dependent cytoskeletal regulation, and acts as a tumor suppressor in B cells by restraining constitutive IL-6 signaling and as a gatekeeper of fatty acid metabolism through direct inhibition of FATP1.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CD37 is a tetraspanin that organizes membrane signaling complexes on leukocytes, coupling receptor compartmentalization to intracellular signal transduction, integrin function, cytoskeletal dynamics, and metabolic control. Upon ligation, CD37 undergoes tyrosine phosphorylation at N-terminal ITIM-like and C-terminal ITAM motifs, recruiting SHP1 to initiate apoptotic signaling or PI3K to promote survival, respectively [PMID:22624718, PMID:40675974]. CD37 restrains IL-6 signaling through interaction with SOCS3, thereby suppressing germinal center–derived B-cell lymphomagenesis and preventing IgA nephropathy; genetic ablation of IL-6 fully rescues both pathologies in CD37-deficient mice [PMID:26784544, PMID:29551516, PMID:19282981]. CD37 also organizes integrins (α4β1, α4β7, αIIbβ3, β2), the BCR complex, dectin-1, CLEC-2, CD20, and FATP1 at the cell surface, regulating integrin-dependent adhesion and Akt survival signaling, Rac-1-dependent dendritic cell and neutrophil migration, BCR endocytosis and MHC class II antigen presentation, platelet activation, and fatty acid uptake [PMID:23150881, PMID:40250439, PMID:40126944, PMID:26566675, PMID:30185523, PMID:38625120, PMID:36100608].\",\n  \"teleology\": [\n    {\n      \"year\": 1989,\n      \"claim\": \"Establishing CD37 as a tetraspanin resolved the fundamental question of its membrane topology, revealing four transmembrane domains with short cytoplasmic tails and an extracellular loop bearing N-linked glycosylation sites.\",\n      \"evidence\": \"cDNA cloning and primary sequence analysis of the 244-amino acid protein\",\n      \"pmids\": [\"2466944\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No information on post-translational modifications beyond glycosylation\", \"Functional role of the short cytoplasmic domains unknown\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Demonstrating that CD37 co-precipitates with MHC class II, CD19, and other tetraspanins established that it participates in large multicomponent membrane complexes on B cells, raising the question of its organizing function.\",\n      \"evidence\": \"Co-immunoprecipitation and preclearing experiments from B-cell lines and tonsillar B cells\",\n      \"pmids\": [\"8119731\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD37 directly contacts MHC II or interacts indirectly through tetraspanin networks\", \"Functional consequence of complex formation unknown\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"The first CD37 knockout mice revealed impaired T-cell-dependent IgG1 responses, establishing a non-redundant role for CD37 in humoral immunity and T–B cell cooperation.\",\n      \"evidence\": \"Cd37−/− mice immunized with T-dependent antigens with and without adjuvant, serum Ig quantification\",\n      \"pmids\": [\"10891477\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which CD37 supports T–B interaction undefined\", \"Whether the defect is B-cell- or T-cell-intrinsic unresolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showing that CD37 deficiency causes T-cell hyperproliferation with enhanced Lck kinase activity, and that CD37 cross-linking inhibits TCR-driven proliferation, revealed CD37 as a negative regulator of proximal TCR signaling.\",\n      \"evidence\": \"Cd37−/− T-cell proliferation assays, Lck activity measurement, CD37 cross-linking on human T cells\",\n      \"pmids\": [\"14978098\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical connection between CD37 and the TCR/Lck complex not shown\", \"Mechanism of Lck suppression unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identification of dectin-1 as a CD37 partner on APCs, where CD37 stabilizes dectin-1 surface expression and restrains dectin-1-induced IL-6 production, provided the first evidence that CD37 negatively controls innate immune cytokine output.\",\n      \"evidence\": \"Co-localization, Cd37−/− macrophage cytokine assays, rescue by CD37 transfection\",\n      \"pmids\": [\"17182550\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of dectin-1 internalization control by CD37 not defined\", \"Whether CD37-dectin-1 interaction is direct or within tetraspanin web unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating that CD37 loss causes 15-fold elevated IgA via B-cell-intrinsic IL-6 overproduction—reversible by IL-6 neutralization—identified the CD37/IL-6 axis as a master regulator of IgA class switching, linking CD37 to IgA nephropathy pathogenesis.\",\n      \"evidence\": \"Cd37−/− mice, bone marrow chimeras, IL-6 neutralization in vivo, serum IgA quantification\",\n      \"pmids\": [\"19282981\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CD37 restrains IL-6 at the molecular level not yet identified\", \"Relevance to human IgA nephropathy not directly tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Mapping ITIM-like (N-terminal Tyr → SHP1 → apoptosis) and ITAM (C-terminal Tyr → PI3K → survival) motifs on CD37 established it as a direct signal transducer, not merely a membrane organizer, resolving a long-standing question about tetraspanin signaling competence.\",\n      \"evidence\": \"Site-directed mutagenesis of tyrosine residues, SHP1 Co-IP, PI3K pathway analysis, apoptosis assays\",\n      \"pmids\": [\"22624718\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the kinase(s) that phosphorylate CD37 tyrosines unknown\", \"Whether both motifs are simultaneously active in the same cell context unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showing that CD37 controls α4β1 integrin clustering and VCAM-1-dependent Akt activation in plasma cells linked the tetraspanin membrane-organizing function to integrin-mediated survival signaling in germinal centers.\",\n      \"evidence\": \"Cd37−/− mice, integrin clustering imaging, Akt phosphorylation, VCAM-1 binding assays\",\n      \"pmids\": [\"23150881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD37 directly binds α4β1 or acts through lateral tetraspanin interactions not resolved\", \"Structural basis of integrin clustering by CD37 unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating that CD37 is required for DC migration from skin to lymph nodes, chemotaxis, and integrin-mediated adhesion under flow established CD37 as essential for cellular immunity beyond humoral responses.\",\n      \"evidence\": \"Cd37−/− mice, intravital multiphoton imaging, in vitro chemotaxis and flow chamber assays\",\n      \"pmids\": [\"23420539\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific integrin(s) organized by CD37 during DC migration not identified\", \"Downstream cytoskeletal effector undefined at this stage\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying dysregulated Rac-1 activation and accelerated β2 integrin internalization in CD37-deficient neutrophils established a cytoskeletal mechanism—Rac-1-dependent actin polymerization—for CD37's role in leukocyte adhesion and migration.\",\n      \"evidence\": \"Cd37−/− neutrophils, peritonitis model, intravital microscopy, superresolution microscopy, Rac-1 activation assays\",\n      \"pmids\": [\"26566675\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CD37 activates Rac-1 (direct or via GEF recruitment) unknown\", \"Superresolution showed CD37 and CD18 do not co-cluster, so the spatial mechanism of action remains unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of SOCS3 as a CD37 interaction partner, combined with genetic epistasis showing that IL-6 deletion rescues CD37−/− lymphomagenesis, established CD37 as a tumor suppressor acting through SOCS3-dependent restraint of constitutive IL-6 signaling.\",\n      \"evidence\": \"Co-IP (CD37–SOCS3), Cd37−/− lymphoma model, Cd37/Il6 double-knockout rescue\",\n      \"pmids\": [\"26784544\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD37 stabilizes SOCS3 protein levels or recruits it to IL-6 receptor complexes not distinguished\", \"Applicability to human DLBCL treatment not functionally tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Genetic epistasis confirmed that IL-6 is the causative mediator of IgA nephropathy in CD37-deficient mice, as Cd37/Il6 double knockouts were fully protected from glomerular IgA deposition and renal failure.\",\n      \"evidence\": \"Cd37/Il6 double-knockout mice, renal histopathology, IgA and IL-6 quantification\",\n      \"pmids\": [\"29551516\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Translational relevance to human IgA nephropathy not validated\", \"Whether therapeutic IL-6 blockade recapitulates the protective effect untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showing that CD37 directly interacts with CLEC-2 and is required for CLEC-2-dependent DC migration and actin protrusion formation upon podoplanin stimulation extended CD37's organizing function to C-type lectin receptor–mediated migration.\",\n      \"evidence\": \"Co-IP (CLEC-2/CD37), Cd37−/− DC migration in 3D collagen matrices, microcontact printing\",\n      \"pmids\": [\"30185523\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD37 controls CLEC-2 signaling beyond surface stabilization unknown\", \"Role in lymph node architecture in vivo not fully characterized\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Discovery that CD37 directly binds FATP1 and inhibits fatty acid uptake and oxidation in B-cell lymphoma expanded CD37's functional repertoire to metabolic regulation, with FATP1 inhibition reversing the metabolic phenotype of CD37-deficient cells.\",\n      \"evidence\": \"Co-IP (CD37–FATP1), FA oxidation assays, metabolomics, FATP1 inhibitor rescue, in vivo mouse studies\",\n      \"pmids\": [\"36100608\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of CD37–FATP1 interaction unknown\", \"Whether metabolic control contributes to CD37's tumor suppressor function independently of IL-6 pathway not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying IRF8 as a direct transcriptional activator of CD37 via promoter binding addressed the upstream regulation of CD37 expression, providing a mechanistic basis for CD37 loss in DLBCL lacking IRF8.\",\n      \"evidence\": \"DNA pulldown/mass spectrometry, ChIP, IRF8 overexpression, CRISPR/Cas9 IRF8 knockout in DLBCL\",\n      \"pmids\": [\"35086136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Other transcription factors regulating CD37 not explored\", \"Whether IRF8 loss explains CD37 downregulation across all lymphoma subtypes unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mutagenesis of N-glycosylation sites showed glycosylation is required for CD37 surface expression and modulates partner interactions (CD53, CD20) in a localization-dependent manner, while IL-6Rα interaction is glycosylation-independent.\",\n      \"evidence\": \"Glycosylation mutants, flow cytometry, single-molecule dSTORM super-resolution microscopy, Co-IP\",\n      \"pmids\": [\"38031400\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific glycan structures are functionally important not defined\", \"Impact of glycosylation on CD37 signaling through ITIM/ITAM motifs not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrating that CD20 forms a complex with CD37 and stabilizes its surface expression—with CD20 knockout causing CD37 downregulation and increased internalization—revealed reciprocal stabilization within the tetraspanin network relevant to antibody therapy.\",\n      \"evidence\": \"CD20 KO cell lines, Co-IP (CD20/CD37), internalization assays, CDC assays\",\n      \"pmids\": [\"38846084\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD37 reciprocally stabilizes CD20 not tested\", \"Implications for sequential anti-CD20/anti-CD37 therapy not clinically validated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Proximity proteomics identified CD37 as a BCR-proximal protein; CD37 knockout heightened BCR signaling, slowed BCR endocytosis, and reduced pMHC-II formation, establishing CD37 as a modulator of antigen processing via BCR dynamics.\",\n      \"evidence\": \"BioID proximity labeling + mass spectrometry, CRISPR CD37 KO, BCR signaling and endocytosis assays, MHC II antigen presentation assay\",\n      \"pmids\": [\"38625120\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical contact between CD37 and specific BCR subunits not confirmed by reciprocal IP\", \"Whether CD37's effect on BCR is through lateral membrane organization or direct binding not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extension of CD37's integrin-organizing function to platelets (αIIbβ3) and AML leukemic stem cells (α4β7/PI3K-AKT) demonstrated tissue-broad roles in integrin signaling, thrombosis regulation, and leukemia maintenance.\",\n      \"evidence\": \"Cd37−/− platelet assays, FeCl3 carotid thrombosis model, bone marrow chimeras; Co-IP (CD37/α4β7), AML serial transplantation in Cd37 KO mice\",\n      \"pmids\": [\"40126944\", \"40250439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural interface between CD37 and different integrins not characterized\", \"Whether CD37-integrin interactions are direct or mediated by other tetraspanins not resolved for all integrin partners\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of tumor-derived MIF as an extrinsic CD37 ligand that triggers Y13 phosphorylation, SHP1 recruitment, and AKT inhibition in macrophages revealed a tumor immune evasion mechanism operating through CD37's ITIM-like motif.\",\n      \"evidence\": \"Direct MIF-CD37 binding assays, Y13 phosphorylation identification, SHP1/AKT signaling, in vitro phagocytosis and in vivo tumor models\",\n      \"pmids\": [\"40675974\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MIF binding to CD37 occurs in physiological non-tumor contexts unknown\", \"Crystal structure of MIF-CD37 interaction not available\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The identity of the kinase(s) phosphorylating CD37 ITIM-like and ITAM tyrosines, the structural basis of CD37–integrin and CD37–FATP1 interactions, and whether CD37's metabolic and IL-6-restraining tumor suppressor functions operate independently or synergistically remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No kinase identified for CD37 tyrosine phosphorylation\", \"No atomic-resolution structure of CD37 or its complexes\", \"Relative contribution of metabolic vs. IL-6 pathway control to tumor suppression not dissected\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 5, 9, 14, 19, 20]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [8, 22]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 12, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 9, 18, 19]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 4, 5, 6, 7, 10, 11, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 9, 12, 21, 22]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [8, 22]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [16]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [24]}\n    ],\n    \"complexes\": [\n      \"Tetraspanin-enriched microdomain (TEM)\",\n      \"CD20-CD37 complex\"\n    ],\n    \"partners\": [\n      \"SHP1\",\n      \"SOCS3\",\n      \"CLEC2\",\n      \"FATP1\",\n      \"CD20\",\n      \"ITGA4\",\n      \"ITGB1\",\n      \"MIF\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}