{"gene":"ADGRE2","run_date":"2026-06-09T22:02:41","timeline":{"discoveries":[{"year":2000,"finding":"EMR2 (ADGRE2) is a member of the EGF-TM7 family of class B GPCRs, contains five tandem EGF-like domains coupled to a seven-span transmembrane domain via a mucin-like spacer, and expresses multiple protein isoforms via alternative RNA splicing. Expression is restricted to monocytes/macrophages and granulocytes, unlike the ubiquitously expressed paralog CD97. EMR2 fails to interact with CD55, the cellular ligand for CD97, indicating distinct ligand specificity.","method":"Genomic mapping, molecular cloning, monoclonal antibody generation, flow cytometry, ligand-binding assays","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (cloning, antibody binding, flow cytometry, ligand assays) in a single foundational characterization paper","pmids":["10903844"],"is_preprint":false},{"year":2002,"finding":"EMR2 is expressed as a heterodimeric receptor on the cell surface, consisting of an extracellular alpha subunit and a seven-pass transmembrane/cytoplasmic beta subunit. Expression is restricted to myeloid cells (highest on CD16+ monocytes, macrophages, and BDCA-3+ myeloid DC), and EMR2 does not interact with CD55 (the CD97 ligand), confirming non-redundant functions for the two molecular twins.","method":"Monoclonal antibody generation (2A1), immunoprecipitation, flow cytometry on primary blood leukocytes, hematopoietic cell lines, and in situ tissue analysis","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal immunoprecipitation demonstrating heterodimer, flow cytometry with specific mAb, consistent with prior genomic data","pmids":["11994511"],"is_preprint":false},{"year":2003,"finding":"The largest EMR2 isoform (containing 5 EGF-like modules) mediates cell attachment through binding to chondroitin sulfate (CS) glycosaminoglycans. The fourth EGF-like module is the major ligand-binding site. The interaction is Ca2+- and sulphation-dependent. Mutant CHO cell lines defective in GAG biosynthesis and enzymatic removal of cell-surface GAGs demonstrated that CS is the molecular identity of the EMR2 ligand. Exogenous CS GAGs blocked the interaction in a dose-dependent manner.","method":"Multivalent protein probes, antibody-blocking studies, mutant CHO cell lines (GAG biosynthesis-deficient), enzymatic GAG removal, dose-dependent inhibition assays","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods including genetic (mutant CHO lines), biochemical (enzymatic removal, dose-response inhibition), and isoform-specific binding assays in a single rigorous study","pmids":["12829604"],"is_preprint":false},{"year":2003,"finding":"Proteolytic cleavage of EMR2 occurs at Leu517-Ser518 within the GPS motif and is independent of the transmembrane domains. The non-covalent association of the resulting extracellular alpha-subunit and transmembrane beta-subunit requires a minimum of eight amino acids in the beta-subunit. The GPS motif is necessary but not sufficient for cleavage; the entire extracellular stalk is required. An alternatively spliced EMR2 isoform with a truncated stalk fails to undergo proteolytic cleavage, demonstrating that alternative splicing regulates GPS cleavage.","method":"Site-directed mutagenesis, biochemical cleavage assays, analysis of alternatively spliced isoforms, cell-free system","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 / Moderate — site-directed mutagenesis combined with biochemical and cell-free cleavage assays defining precise cleavage site and structural requirements","pmids":["12860403"],"is_preprint":false},{"year":2004,"finding":"GPS proteolysis of EMR2 is an autocatalytic intramolecular reaction. Cleavage occurs at the conserved His-Leu↓Ser518 site inside the endoplasmic reticulum, producing two protein subunits that associate non-covalently as a heterodimer. The P(+1) Ser518 residue (Ser, Thr, or Cys) is absolutely required for efficient proteolysis. Substitution of the P(-2) His residue produces slow-processing precursor proteins that spontaneously hydrolyze in a cell-free system, indicating the mechanism is similar to N-terminal nucleophile hydrolases performing cis-proteolysis.","method":"Site-directed mutagenesis of cleavage site residues, cell-free proteolysis assay, biochemical characterization of processing intermediates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution in cell-free system plus mutagenesis of multiple residues defining mechanistic requirements, replicated across constructs","pmids":["15150276"],"is_preprint":false},{"year":2004,"finding":"The fourth EGF domain of both CD97 and EMR2 is expressed on activated lymphocytes and myeloid cells and mediates binding to chondroitin sulfate specifically found on B cells within peripheral blood, suggesting a role in interaction of activated T cells, dendritic cells, and macrophages with B cells.","method":"Fluorescent beads coated with recombinant CD97 and EMR2 protein, isoform-specific monoclonal antibodies, flow cytometry on primary leukocytes","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — recombinant protein binding assays with isoform-specific antibodies, consistent with prior CS ligand identification","pmids":["15498814"],"is_preprint":false},{"year":2005,"finding":"Dermatan sulfate (a chondroitin sulfate variant) is identified as the ligand of the largest isoforms of EMR2 and CD97 in rheumatoid synovial tissue. EMR2 is expressed on macrophages and dendritic cells expressing costimulatory molecules and TNF-α in RA synovium. EMR2 expression in the synovial sublining is significantly higher in RA patients compared with OA and ReA controls.","method":"Immunohistochemistry with anti-EMR2 mAb, digital image analysis, double immunofluorescence microscopy, multivalent fluorescent probe binding assays on synovial tissue sections","journal":"Arthritis and rheumatism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct ligand binding assays on tissue sections with isoform-specific multivalent probes plus immunohistochemistry with co-localization","pmids":["15693006"],"is_preprint":false},{"year":2006,"finding":"EMR2 receptor expression is up-regulated during differentiation and maturation of macrophages, and down-regulated during dendritic cell maturation. In monocytes and macrophages, EMR2 is specifically up-regulated by LPS and IL-10 via an IL-10-mediated pathway. Alternative splicing and glycosylation of EMR2 are regulated during myeloid differentiation.","method":"Flow cytometry, quantitative PCR, functional stimulation assays with LPS and cytokines, analysis of primary myeloid cells during differentiation","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple cytokine stimulation experiments with pathway specificity (IL-10 pathway), flow cytometry across differentiation states","pmids":["17174274"],"is_preprint":false},{"year":2007,"finding":"Ligation of EMR2 via a specific antibody increases neutrophil adhesion and migration, augments superoxide production and proteolytic enzyme degranulation, and potentiates the effects of proinflammatory mediators. Upon neutrophil activation, EMR2 is rapidly translocated to membrane ruffles and the leading edge of the cell. The transmembrane region is critical for adhesion-GPCR function.","method":"Anti-EMR2 antibody ligation, superoxide assay, degranulation assay, neutrophil adhesion and migration assays, live-cell imaging of receptor translocation","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays (adhesion, migration, superoxide, degranulation) combined with live imaging of receptor translocation, showing specific functional consequences of EMR2 ligation","pmids":["17928360"],"is_preprint":false},{"year":2012,"finding":"GPS autoproteolysis of EMR2 generates two distinct receptor complexes: a noncovalent α-β heterodimer and two completely independent receptor subunits. These distribute differentially in membrane raft microdomains. Receptor ligation induces subunit translocation and colocalization within lipid rafts, leading to receptor signaling and inflammatory cytokine production by macrophages. GPS autoproteolysis is critical for mediating receptor signaling and cell activation.","method":"Lipid raft fractionation, co-immunoprecipitation, live-cell imaging, cytokine ELISA, GPS-mutant receptor constructs, macrophage stimulation assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (fractionation, co-IP, imaging, functional cytokine assay, mutant receptors) in a single rigorous study demonstrating mechanistic role of GPS cleavage in signaling","pmids":["22310662"],"is_preprint":false},{"year":2011,"finding":"EMR2 ligation suppresses LPS-induced neutrophil survival (pro-apoptotic effect). EMR2 ligation also changes the secretion profiles of multiple cytokines, including IL-6, IL-8, and MCP-1, in LPS-treated neutrophils.","method":"Anti-EMR2 mAb (2A1) ligation, flow cytometry (annexin-V/PI apoptosis), ELISA for cytokine secretion, reactive oxygen species assay","journal":"Chang Gung medical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional assays with specific mAb ligation in a single lab study, limited mechanistic depth","pmids":["22035891"],"is_preprint":false},{"year":2016,"finding":"A missense variant in ADGRE2 (p.C492Y) cosegregates with autosomal dominant vibratory urticaria in two large kindreds. The ADGRE2 receptor undergoes autocatalytic cleavage producing an extracellular subunit that noncovalently binds a transmembrane subunit. The p.C492Y variant destabilizes the autoinhibitory subunit interaction, sensitizing mast cells to IgE-independent vibration-induced degranulation.","method":"Genetic cosegregation analysis in human kindreds, functional studies of variant receptor in mast cells (degranulation assays), biochemical analysis of subunit interaction","journal":"The New England journal of medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic cosegregation plus functional mast cell degranulation assays plus biochemical subunit interaction analysis, replicated in two independent kindreds","pmids":["26841242"],"is_preprint":false},{"year":2017,"finding":"Activation of EMR2 via a receptor-specific monoclonal antibody promotes differentiation of human THP-1 monocytic cells and induces expression of pro-inflammatory mediators (IL-8, TNF-α, MMP-9). EMR2-mediated signaling is initiated by Gα16, followed by sequential activation of Akt, ERK, JNK, and NF-κB. siRNA knockdown of specific signaling intermediates confirmed the pathway.","method":"Anti-EMR2 mAb stimulation, siRNA knockdown of signaling intermediates, specific signaling inhibitors, ELISA, western blotting, THP-1 differentiation assays","journal":"Frontiers in immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — pathway dissected using both pharmacological inhibitors and siRNA knockdowns of multiple nodes (Gα16, Akt, ERK, JNK, NF-κB), multiple orthogonal functional readouts","pmids":["28421075"],"is_preprint":false},{"year":2018,"finding":"The membrane association of the EMR2 N-terminal fragment (NTF) after GPS autoproteolysis is regulated by site-specific N-glycosylation within the GAIN domain, occurring in post-ER compartments. A unique amphipathic α-helix in the GAIN domain serves as a putative membrane anchor for the membrane-associated NTF subtype.","method":"Glycosylation site mutagenesis, subcellular fractionation, biochemical characterization of NTF subtypes, domain deletion analysis","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-directed mutagenesis of glycosylation sites combined with fractionation and domain analysis in a single lab study","pmids":["29540735"],"is_preprint":false},{"year":2020,"finding":"ADGRE2/EMR2 and ADGRE5/CD97 are functionally G protein-coupled receptors. Using activated truncated receptor forms in a yeast-based assay with chimeric G proteins, EMR2 showed broad G protein-coupling, while CD97 coupled more specifically to Gα12, Gα13, Gα14, and Gαz chimeras. Both receptors induced pertussis-toxin insensitive inhibition of cAMP, suggesting coupling to Gαz. EMR2 signals via Gα16 and a Gα16/Gαz chimera to stimulate IP1 accumulation. A polyclonal antibody was identified that activates EMR2 G protein signaling in vitro.","method":"Yeast-based GPCR/chimeric G protein coupling assay, cAMP inhibition assay in mammalian cells, IP1 accumulation assay, NFAT reporter assay, pertussis toxin treatment","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple recombinant assay systems (yeast, mammalian) with pharmacological validation (PTX) in a single lab study","pmids":["31969668"],"is_preprint":false},{"year":2020,"finding":"Mechanical activation (vibration) of mast cells expressing p.C492Y-ADGRE2 attached to dermatan sulfate triggers phospholipase C activation, transient cytosolic calcium increases, and downstream activation of PI3K and ERK1/2, mediated by Gβγ, Gαq/11, and through Gαi/o-independent mechanisms. Degranulation was dependent on PLC pathways (calcium, PKC, PI3K) and pertussis toxin-sensitive signals. Mechanoactivation also stimulated prostaglandin D2 synthesis via ERK1/2, calcium, PKC, and PI3K.","method":"Vibration stimulation of human mast cells on dermatan sulfate substrate, calcium imaging, pharmacological inhibitors of PLC/PKC/PI3K/ERK, pertussis toxin treatment, prostaglandin D2 ELISA, degranulation assay","journal":"The Journal of investigative dermatology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal pharmacological dissections of the signaling pathway with functional readouts (degranulation, PGD2), pertussis toxin validation, using physiologically relevant variant receptor on its natural ligand","pmids":["32222457"],"is_preprint":false},{"year":2019,"finding":"EMR2/ADGRE2 contains an SGD sequence (corresponding to the RGD integrin-binding motif in CD97). Unlike CD97, EMR2 fails to induce angiogenesis or upregulate MMP-9. However, a single change of the SGD to RGD sequence in EMR2 allows it to up-regulate MMP-9 expression, leading to enhanced angiogenesis. MMP-9 promotes HUVEC proliferation, migration, and invasion by modulating VEGF, PIGF, and bFGF levels. MMP-9 expression is modulated by N-cadherin, which is upregulated by both CD97 and EMR2/RGD.","method":"Site-directed mutagenesis (SGD→RGD), in vitro endothelial tube formation assay, in ovo chick chorioallantoic membrane assay, MMP-9 expression analysis, VEGF/PIGF/bFGF measurement","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function mutagenesis with multiple functional angiogenesis readouts, single lab study","pmids":["31594642"],"is_preprint":false},{"year":2021,"finding":"EMR2 stimulation by its agonistic 2A1 monoclonal antibody activates the NLRP3 inflammasome second signal in THP-1 monocytic cells and primary monocytes via a Gα16-dependent PLC-β activation pathway, inducing downstream Akt, MAPK, NF-κB activation and Ca2+ mobilization, ultimately leading to K+ efflux.","method":"Anti-EMR2 mAb (2A1) stimulation, siRNA knockdown, pharmacological inhibitors, K+ efflux measurement, Ca2+ mobilization assay, NLRP3 inflammasome activation assay in THP-1 and primary monocytes","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA and pharmacological dissection of pathway from EMR2 to NLRP3 with multiple downstream readouts, single lab study","pmids":["33488598"],"is_preprint":false},{"year":2024,"finding":"ADGRE2 activates phospholipase Cβ/protein kinase C/MEK/ERK signaling to enhance expression of AP1 transcription factor, which transcriptionally drives DUSP1 (a protein phosphatase). DUSP1 dephosphorylates Ser16 in the J-domain of co-chaperone DNAJB1, facilitating the DNAJB1-HSP70 interaction and maintenance of proteostasis in AML. Silencing ADGRE2 exerts antileukemic effects in AML cell lines and patient-derived cells in vitro, and delays AML progression in xenograft models.","method":"siRNA/shRNA knockdown, xenograft mouse models, pharmacological inhibitors of MEK/AP1/DUSP1, phosphorylation analysis (DUSP1 Ser16), co-immunoprecipitation (DNAJB1-HSP70), transcriptional reporter assays","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — pathway mechanistically dissected from receptor to proteostasis via multiple orthogonal methods (KD, inhibitors, co-IP, phospho-analysis, xenograft), validated in patient-derived cells and in vivo","pmids":["39082681"],"is_preprint":false},{"year":2024,"finding":"CD312/ADGRE2 interacts with GNA15 (Gα15) via its transmembrane intracellular segment. CD312 knockdown reduces Treg cell proportion while increasing CTL proportion in the ALL bone marrow immune microenvironment. Overexpression of CD312 in CD3+ T cells enhances leukemia cell proliferation via phosphorylation of ERK, JNK, and p38, while GNA15 knockdown decreases this proliferative effect.","method":"Co-immunoprecipitation/affinity assay for CD312-GNA15 interaction, CD312 knockdown and overexpression, GNA15 siRNA, BrdU proliferation assay, flow cytometry for immune subsets","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct protein interaction assay (CD312-GNA15) combined with functional knockdown/overexpression and MAPK pathway analysis, single lab study","pmids":["39656442"],"is_preprint":false}],"current_model":"ADGRE2/EMR2 is a myeloid-restricted adhesion GPCR that undergoes autocatalytic intramolecular GPS/GAIN-domain cleavage in the ER at Leu517-Ser518 (requiring a Ser/Thr/Cys at P+1), producing a non-covalent extracellular α-subunit/transmembrane β-subunit heterodimer whose subunit interaction tonically inhibits signaling; upon ligation by its extracellular EGF module 4 to chondroitin/dermatan sulfate ligands, or upon antibody-mediated activation, the subunits translocate into lipid raft microdomains where the receptor couples broadly to G proteins (primarily Gα16, Gαq/11, Gαz, Gβγ) to activate PLC-β → Ca2+/PKC → PI3K/Akt → MAPK/NF-κB cascades, driving neutrophil adhesion/migration/superoxide production, macrophage differentiation and cytokine production, monocyte NLRP3 inflammasome activation, and in AML an MEK/AP1/DUSP1/DNAJB1-HSP70 proteostasis axis; a disease-causing p.C492Y variant destabilizes the autoinhibitory α–β interaction to sensitize mast cells to mechanical (vibratory) degranulation."},"narrative":{"mechanistic_narrative":"ADGRE2 (EMR2/CD312) is a myeloid-restricted adhesion G protein-coupled receptor of the EGF-TM7 family that links extracellular glycosaminoglycan recognition to proinflammatory signaling [PMID:10903844, PMID:12829604]. Its extracellular region carries five tandem EGF-like modules, and the fourth EGF module mediates Ca2+- and sulfation-dependent binding to chondroitin sulfate and the variant dermatan sulfate, defining a ligand specificity distinct from its paralog CD97/CD55 [PMID:12829604, PMID:15498814, PMID:15693006]. The receptor matures by autocatalytic intramolecular cis-proteolysis at the His-Leu↓Ser518 GPS site within the ER, an N-terminal-nucleophile-hydrolase-like reaction requiring a Ser/Thr/Cys at P+1 and the full extracellular stalk, generating a non-covalent extracellular α-subunit/transmembrane β-subunit heterodimer [PMID:12860403, PMID:15150276]. Ligation or antibody-mediated activation drives subunit translocation into lipid raft microdomains, which is required for downstream signaling and cytokine output [PMID:22310662]. The activated receptor couples broadly to G proteins, including Gα16 and Gαq/11, to engage a PLC-β → Ca2+/PKC → PI3K/Akt → MAPK/NF-κB cascade [PMID:28421075, PMID:31969668, PMID:32222457]. Functionally this potentiates neutrophil adhesion, migration, superoxide production and degranulation [PMID:17928360], promotes monocyte/macrophage differentiation, cytokine secretion and NLRP3 inflammasome activation [PMID:28421075, PMID:33488598], and in AML sustains an MEK/ERK→AP1→DUSP1→DNAJB1-HSP70 proteostasis axis whose disruption is antileukemic [PMID:39082681]. A heterozygous p.C492Y variant that destabilizes the autoinhibitory α–β subunit interaction causes autosomal dominant vibratory urticaria by sensitizing mast cells to mechanical, IgE-independent degranulation [PMID:26841242, PMID:32222457].","teleology":[{"year":2000,"claim":"Established ADGRE2/EMR2 as a distinct myeloid-restricted EGF-TM7 class B GPCR, separating it from its ubiquitous paralog CD97 and asking what its ligand and function are.","evidence":"Genomic mapping, cloning, monoclonal antibody and flow cytometry on leukocytes, with ligand-binding assays showing no CD55 interaction","pmids":["10903844"],"confidence":"Medium","gaps":["Ligand identity unknown at this stage","No signaling mechanism defined","Functional consequences of expression not addressed"]},{"year":2002,"claim":"Showed the receptor exists at the cell surface as a two-subunit heterodimer (extracellular α + 7TM β), establishing the architecture later linked to autoproteolysis and autoinhibition.","evidence":"Reciprocal immunoprecipitation and flow cytometry with the 2A1 mAb on primary leukocytes and cell lines","pmids":["11994511"],"confidence":"Medium","gaps":["Mechanism generating the heterodimer not yet defined","Subunit interaction strength/regulation unknown"]},{"year":2003,"claim":"Identified chondroitin sulfate as the molecular ligand and localized binding to the fourth EGF module, answering what ADGRE2 recognizes extracellularly.","evidence":"Multivalent protein probes, GAG-biosynthesis-deficient CHO mutants, enzymatic GAG removal and dose-dependent inhibition","pmids":["12829604"],"confidence":"High","gaps":["Physiological cellular source of CS ligand in vivo not defined","Signaling consequence of ligation not yet measured"]},{"year":2003,"claim":"Defined the GPS cleavage site at Leu517-Ser518 and showed the full extracellular stalk (not the GPS motif alone) is required, with alternative splicing controlling whether cleavage occurs.","evidence":"Site-directed mutagenesis, biochemical and cell-free cleavage assays, analysis of spliced isoforms","pmids":["12860403"],"confidence":"High","gaps":["Catalytic chemistry of cleavage not yet established","Functional role of cleavage in signaling unaddressed"]},{"year":2004,"claim":"Demonstrated GPS proteolysis is an autocatalytic intramolecular reaction occurring in the ER, mechanistically resembling N-terminal nucleophile hydrolases.","evidence":"Mutagenesis of P+1/P-2 residues and cell-free spontaneous hydrolysis of slow-processing precursors","pmids":["15150276"],"confidence":"High","gaps":["Link between cleavage and receptor activation not yet demonstrated","Fate of subunits after cleavage unclear"]},{"year":2005,"claim":"Extended ligand recognition to a cellular context, showing EGF4-mediated CS binding targets B cells, implying immune cell–cell interactions.","evidence":"Recombinant protein-coated beads and isoform-specific mAbs on primary leukocytes","pmids":["15498814"],"confidence":"Medium","gaps":["Functional consequence of the EMR2–B cell interaction not tested","In vivo relevance not established"]},{"year":2005,"claim":"Connected ADGRE2 to inflammatory disease by identifying dermatan sulfate as a ligand and showing elevated EMR2 on activated macrophages/DCs in rheumatoid synovium.","evidence":"Immunohistochemistry, immunofluorescence colocalization and multivalent probe binding on synovial tissue","pmids":["15693006"],"confidence":"Medium","gaps":["Causal role in RA pathogenesis not demonstrated","Downstream signaling in synovial cells not measured"]},{"year":2006,"claim":"Showed ADGRE2 expression is dynamically regulated during myeloid differentiation and induced by LPS and IL-10, framing it as an inducible inflammatory receptor.","evidence":"Flow cytometry, qPCR and cytokine stimulation of primary myeloid cells","pmids":["17174274"],"confidence":"Medium","gaps":["Transcriptional regulators not identified","Functional output of regulated expression not tested here"]},{"year":2007,"claim":"Provided the first direct functional evidence that receptor ligation drives effector responses, establishing ADGRE2 as a proinflammatory neutrophil receptor.","evidence":"Anti-EMR2 antibody ligation with adhesion, migration, superoxide, degranulation assays and live imaging of receptor translocation","pmids":["17928360"],"confidence":"High","gaps":["G protein and second-messenger pathway not defined","Endogenous ligand-triggered responses not tested"]},{"year":2011,"claim":"Identified additional neutrophil outcomes of ligation, including suppression of LPS-induced survival and altered cytokine secretion.","evidence":"2A1 mAb ligation with apoptosis, ROS and cytokine ELISA assays","pmids":["22035891"],"confidence":"Medium","gaps":["Single-lab functional study with limited mechanistic depth","Signaling intermediates not mapped"]},{"year":2012,"claim":"Linked GPS autoproteolysis to signaling by showing ligation drives subunit translocation and colocalization in lipid rafts, which is required for cytokine production.","evidence":"Lipid raft fractionation, co-IP, live imaging, GPS-mutant constructs and macrophage cytokine assays","pmids":["22310662"],"confidence":"High","gaps":["Identity of raft-resident signaling partners not defined","G protein specificity not yet resolved"]},{"year":2016,"claim":"Established a Mendelian disease link, showing the p.C492Y variant destabilizes the α–β interaction and causes autosomal dominant vibratory urticaria via mast cell sensitization.","evidence":"Cosegregation in two kindreds plus mast cell degranulation and subunit-interaction biochemistry","pmids":["26841242"],"confidence":"High","gaps":["Downstream mechanotransduction signaling not yet dissected","How subunit destabilization couples to force sensing unclear"]},{"year":2017,"claim":"Defined the canonical signaling cascade in monocytes, placing Gα16 upstream of sequential Akt/ERK/JNK/NF-κB activation driving differentiation and proinflammatory mediator expression.","evidence":"Anti-EMR2 mAb stimulation with siRNA knockdown and inhibitors of pathway nodes in THP-1 cells","pmids":["28421075"],"confidence":"High","gaps":["Direct receptor–Gα16 coupling biochemistry not shown here","Endogenous ligand-driven cascade not tested"]},{"year":2018,"claim":"Refined post-cleavage receptor biology by showing site-specific GAIN-domain N-glycosylation and an amphipathic helix control membrane association of the N-terminal fragment.","evidence":"Glycosylation-site mutagenesis, subcellular fractionation and domain deletion analysis","pmids":["29540735"],"confidence":"Medium","gaps":["Functional consequence of NTF membrane anchoring for signaling unknown","Single-lab biochemical study"]},{"year":2020,"claim":"Confirmed ADGRE2 is a functional GPCR with broad G protein coupling, including Gα16 and PTX-insensitive Gαz, distinguishing it from CD97's narrower coupling.","evidence":"Yeast chimeric G protein assay, cAMP inhibition, IP1 accumulation and NFAT reporter with pertussis toxin","pmids":["31969668"],"confidence":"Medium","gaps":["Coupling tested with truncated/activated forms, not native ligand","Physiological G protein usage in primary cells not confirmed"]},{"year":2020,"claim":"Mechanistically dissected the disease pathway, showing variant-receptor mechanoactivation on dermatan sulfate triggers PLC/Ca2+/PKC/PI3K/ERK signaling and PGD2 synthesis driving degranulation.","evidence":"Vibration stimulation of mast cells on dermatan sulfate with calcium imaging, pathway inhibitors, pertussis toxin and PGD2 ELISA","pmids":["32222457"],"confidence":"High","gaps":["Direct force-sensing molecular event not resolved","Contribution of specific Gα subunits to mechanosignaling only partially defined"]},{"year":2019,"claim":"Used SGD→RGD swap to show ADGRE2 lacks the integrin motif of CD97 and does not promote angiogenesis, clarifying functional divergence from its paralog.","evidence":"Site-directed mutagenesis with endothelial tube formation, CAM assay and MMP-9/VEGF analysis","pmids":["31594642"],"confidence":"Medium","gaps":["Endogenous angiogenic role of wild-type EMR2 remains negative/uncharacterized","Single-lab gain-of-function study"]},{"year":2021,"claim":"Extended the Gα16/PLC-β cascade to innate immune activation, showing EMR2 stimulation licenses the NLRP3 inflammasome second signal via Akt/MAPK/NF-κB, Ca2+ and K+ efflux.","evidence":"2A1 mAb stimulation with siRNA, inhibitors, K+ efflux and Ca2+ assays in THP-1 and primary monocytes","pmids":["33488598"],"confidence":"Medium","gaps":["Endogenous ligand triggering of inflammasome not tested","Single-lab study"]},{"year":2024,"claim":"Revealed a pro-leukemic role in AML, linking the PLC-β/PKC/MEK/ERK→AP1→DUSP1 axis to DNAJB1-HSP70 chaperone function and proteostasis maintenance.","evidence":"siRNA/shRNA knockdown, MEK/AP1/DUSP1 inhibitors, DUSP1 Ser16 phospho-analysis, DNAJB1-HSP70 co-IP and xenograft models in patient-derived AML cells","pmids":["39082681"],"confidence":"High","gaps":["Upstream ligand/activation trigger in AML cells not defined","Whether autoproteolysis is required for the leukemic axis untested"]},{"year":2024,"claim":"Identified a direct intracellular interaction with Gα15/GNA15 and a T-cell-associated pro-leukemic effect in ALL, supporting G protein engagement and microenvironmental immune modulation.","evidence":"Co-IP/affinity assay for CD312-GNA15, knockdown/overexpression, BrdU proliferation and flow cytometry of immune subsets","pmids":["39656442"],"confidence":"Medium","gaps":["Single Co-IP for the CD312-GNA15 interaction","Mechanism of T-cell-mediated leukemia support beyond MAPK phosphorylation unclear"]},{"year":null,"claim":"How endogenous chondroitin/dermatan sulfate ligation, mechanical force, and subunit dissociation are integrated into a unified activation mechanism, and whether autoproteolysis is required across all disease contexts, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the activated ligand-bound receptor","Force-sensing molecular event not defined","Native-ligand-driven (vs antibody-driven) signaling incompletely characterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[12,14,17]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,4]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[2,5,8]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[3,4]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,8,9]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[8,12,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[12,14,15]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[11,15,18]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[18]}],"complexes":[],"partners":["GNA15"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UHX3","full_name":"Adhesion G protein-coupled receptor E2","aliases":["EGF-like module receptor 2","EGF-like module-containing mucin-like hormone receptor-like 2"],"length_aa":823,"mass_kda":90.5,"function":"Cell surface receptor that binds to the chondroitin sulfate moiety of glycosaminoglycan chains and promotes cell attachment. Promotes granulocyte chemotaxis, degranulation and adhesion. In macrophages, promotes the release of inflammatory cytokines, including IL8 and TNF. Signals probably through G-proteins. Is a regulator of mast cell degranulation (PubMed:26841242)","subcellular_location":"Cell membrane; Cell projection, ruffle membrane","url":"https://www.uniprot.org/uniprotkb/Q9UHX3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ADGRE2","classification":"Not Classified","n_dependent_lines":27,"n_total_lines":1208,"dependency_fraction":0.022350993377483443},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ADGRE2","total_profiled":1310},"omim":[{"mim_id":"606100","title":"ADHESION G PROTEIN-COUPLED RECEPTOR E2; ADGRE2","url":"https://www.omim.org/entry/606100"},{"mim_id":"125630","title":"VIBRATORY URTICARIA; VBU","url":"https://www.omim.org/entry/125630"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid 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Expression is restricted to monocytes/macrophages and granulocytes, unlike the ubiquitously expressed paralog CD97. EMR2 fails to interact with CD55, the cellular ligand for CD97, indicating distinct ligand specificity.\",\n      \"method\": \"Genomic mapping, molecular cloning, monoclonal antibody generation, flow cytometry, ligand-binding assays\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (cloning, antibody binding, flow cytometry, ligand assays) in a single foundational characterization paper\",\n      \"pmids\": [\"10903844\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"EMR2 is expressed as a heterodimeric receptor on the cell surface, consisting of an extracellular alpha subunit and a seven-pass transmembrane/cytoplasmic beta subunit. Expression is restricted to myeloid cells (highest on CD16+ monocytes, macrophages, and BDCA-3+ myeloid DC), and EMR2 does not interact with CD55 (the CD97 ligand), confirming non-redundant functions for the two molecular twins.\",\n      \"method\": \"Monoclonal antibody generation (2A1), immunoprecipitation, flow cytometry on primary blood leukocytes, hematopoietic cell lines, and in situ tissue analysis\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal immunoprecipitation demonstrating heterodimer, flow cytometry with specific mAb, consistent with prior genomic data\",\n      \"pmids\": [\"11994511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The largest EMR2 isoform (containing 5 EGF-like modules) mediates cell attachment through binding to chondroitin sulfate (CS) glycosaminoglycans. The fourth EGF-like module is the major ligand-binding site. The interaction is Ca2+- and sulphation-dependent. Mutant CHO cell lines defective in GAG biosynthesis and enzymatic removal of cell-surface GAGs demonstrated that CS is the molecular identity of the EMR2 ligand. Exogenous CS GAGs blocked the interaction in a dose-dependent manner.\",\n      \"method\": \"Multivalent protein probes, antibody-blocking studies, mutant CHO cell lines (GAG biosynthesis-deficient), enzymatic GAG removal, dose-dependent inhibition assays\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods including genetic (mutant CHO lines), biochemical (enzymatic removal, dose-response inhibition), and isoform-specific binding assays in a single rigorous study\",\n      \"pmids\": [\"12829604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Proteolytic cleavage of EMR2 occurs at Leu517-Ser518 within the GPS motif and is independent of the transmembrane domains. The non-covalent association of the resulting extracellular alpha-subunit and transmembrane beta-subunit requires a minimum of eight amino acids in the beta-subunit. The GPS motif is necessary but not sufficient for cleavage; the entire extracellular stalk is required. An alternatively spliced EMR2 isoform with a truncated stalk fails to undergo proteolytic cleavage, demonstrating that alternative splicing regulates GPS cleavage.\",\n      \"method\": \"Site-directed mutagenesis, biochemical cleavage assays, analysis of alternatively spliced isoforms, cell-free system\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — site-directed mutagenesis combined with biochemical and cell-free cleavage assays defining precise cleavage site and structural requirements\",\n      \"pmids\": [\"12860403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"GPS proteolysis of EMR2 is an autocatalytic intramolecular reaction. Cleavage occurs at the conserved His-Leu↓Ser518 site inside the endoplasmic reticulum, producing two protein subunits that associate non-covalently as a heterodimer. The P(+1) Ser518 residue (Ser, Thr, or Cys) is absolutely required for efficient proteolysis. Substitution of the P(-2) His residue produces slow-processing precursor proteins that spontaneously hydrolyze in a cell-free system, indicating the mechanism is similar to N-terminal nucleophile hydrolases performing cis-proteolysis.\",\n      \"method\": \"Site-directed mutagenesis of cleavage site residues, cell-free proteolysis assay, biochemical characterization of processing intermediates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution in cell-free system plus mutagenesis of multiple residues defining mechanistic requirements, replicated across constructs\",\n      \"pmids\": [\"15150276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The fourth EGF domain of both CD97 and EMR2 is expressed on activated lymphocytes and myeloid cells and mediates binding to chondroitin sulfate specifically found on B cells within peripheral blood, suggesting a role in interaction of activated T cells, dendritic cells, and macrophages with B cells.\",\n      \"method\": \"Fluorescent beads coated with recombinant CD97 and EMR2 protein, isoform-specific monoclonal antibodies, flow cytometry on primary leukocytes\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — recombinant protein binding assays with isoform-specific antibodies, consistent with prior CS ligand identification\",\n      \"pmids\": [\"15498814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Dermatan sulfate (a chondroitin sulfate variant) is identified as the ligand of the largest isoforms of EMR2 and CD97 in rheumatoid synovial tissue. EMR2 is expressed on macrophages and dendritic cells expressing costimulatory molecules and TNF-α in RA synovium. EMR2 expression in the synovial sublining is significantly higher in RA patients compared with OA and ReA controls.\",\n      \"method\": \"Immunohistochemistry with anti-EMR2 mAb, digital image analysis, double immunofluorescence microscopy, multivalent fluorescent probe binding assays on synovial tissue sections\",\n      \"journal\": \"Arthritis and rheumatism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct ligand binding assays on tissue sections with isoform-specific multivalent probes plus immunohistochemistry with co-localization\",\n      \"pmids\": [\"15693006\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"EMR2 receptor expression is up-regulated during differentiation and maturation of macrophages, and down-regulated during dendritic cell maturation. In monocytes and macrophages, EMR2 is specifically up-regulated by LPS and IL-10 via an IL-10-mediated pathway. Alternative splicing and glycosylation of EMR2 are regulated during myeloid differentiation.\",\n      \"method\": \"Flow cytometry, quantitative PCR, functional stimulation assays with LPS and cytokines, analysis of primary myeloid cells during differentiation\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cytokine stimulation experiments with pathway specificity (IL-10 pathway), flow cytometry across differentiation states\",\n      \"pmids\": [\"17174274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Ligation of EMR2 via a specific antibody increases neutrophil adhesion and migration, augments superoxide production and proteolytic enzyme degranulation, and potentiates the effects of proinflammatory mediators. Upon neutrophil activation, EMR2 is rapidly translocated to membrane ruffles and the leading edge of the cell. The transmembrane region is critical for adhesion-GPCR function.\",\n      \"method\": \"Anti-EMR2 antibody ligation, superoxide assay, degranulation assay, neutrophil adhesion and migration assays, live-cell imaging of receptor translocation\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays (adhesion, migration, superoxide, degranulation) combined with live imaging of receptor translocation, showing specific functional consequences of EMR2 ligation\",\n      \"pmids\": [\"17928360\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"GPS autoproteolysis of EMR2 generates two distinct receptor complexes: a noncovalent α-β heterodimer and two completely independent receptor subunits. These distribute differentially in membrane raft microdomains. Receptor ligation induces subunit translocation and colocalization within lipid rafts, leading to receptor signaling and inflammatory cytokine production by macrophages. GPS autoproteolysis is critical for mediating receptor signaling and cell activation.\",\n      \"method\": \"Lipid raft fractionation, co-immunoprecipitation, live-cell imaging, cytokine ELISA, GPS-mutant receptor constructs, macrophage stimulation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (fractionation, co-IP, imaging, functional cytokine assay, mutant receptors) in a single rigorous study demonstrating mechanistic role of GPS cleavage in signaling\",\n      \"pmids\": [\"22310662\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"EMR2 ligation suppresses LPS-induced neutrophil survival (pro-apoptotic effect). EMR2 ligation also changes the secretion profiles of multiple cytokines, including IL-6, IL-8, and MCP-1, in LPS-treated neutrophils.\",\n      \"method\": \"Anti-EMR2 mAb (2A1) ligation, flow cytometry (annexin-V/PI apoptosis), ELISA for cytokine secretion, reactive oxygen species assay\",\n      \"journal\": \"Chang Gung medical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional assays with specific mAb ligation in a single lab study, limited mechanistic depth\",\n      \"pmids\": [\"22035891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A missense variant in ADGRE2 (p.C492Y) cosegregates with autosomal dominant vibratory urticaria in two large kindreds. The ADGRE2 receptor undergoes autocatalytic cleavage producing an extracellular subunit that noncovalently binds a transmembrane subunit. The p.C492Y variant destabilizes the autoinhibitory subunit interaction, sensitizing mast cells to IgE-independent vibration-induced degranulation.\",\n      \"method\": \"Genetic cosegregation analysis in human kindreds, functional studies of variant receptor in mast cells (degranulation assays), biochemical analysis of subunit interaction\",\n      \"journal\": \"The New England journal of medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic cosegregation plus functional mast cell degranulation assays plus biochemical subunit interaction analysis, replicated in two independent kindreds\",\n      \"pmids\": [\"26841242\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Activation of EMR2 via a receptor-specific monoclonal antibody promotes differentiation of human THP-1 monocytic cells and induces expression of pro-inflammatory mediators (IL-8, TNF-α, MMP-9). EMR2-mediated signaling is initiated by Gα16, followed by sequential activation of Akt, ERK, JNK, and NF-κB. siRNA knockdown of specific signaling intermediates confirmed the pathway.\",\n      \"method\": \"Anti-EMR2 mAb stimulation, siRNA knockdown of signaling intermediates, specific signaling inhibitors, ELISA, western blotting, THP-1 differentiation assays\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pathway dissected using both pharmacological inhibitors and siRNA knockdowns of multiple nodes (Gα16, Akt, ERK, JNK, NF-κB), multiple orthogonal functional readouts\",\n      \"pmids\": [\"28421075\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The membrane association of the EMR2 N-terminal fragment (NTF) after GPS autoproteolysis is regulated by site-specific N-glycosylation within the GAIN domain, occurring in post-ER compartments. A unique amphipathic α-helix in the GAIN domain serves as a putative membrane anchor for the membrane-associated NTF subtype.\",\n      \"method\": \"Glycosylation site mutagenesis, subcellular fractionation, biochemical characterization of NTF subtypes, domain deletion analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-directed mutagenesis of glycosylation sites combined with fractionation and domain analysis in a single lab study\",\n      \"pmids\": [\"29540735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ADGRE2/EMR2 and ADGRE5/CD97 are functionally G protein-coupled receptors. Using activated truncated receptor forms in a yeast-based assay with chimeric G proteins, EMR2 showed broad G protein-coupling, while CD97 coupled more specifically to Gα12, Gα13, Gα14, and Gαz chimeras. Both receptors induced pertussis-toxin insensitive inhibition of cAMP, suggesting coupling to Gαz. EMR2 signals via Gα16 and a Gα16/Gαz chimera to stimulate IP1 accumulation. A polyclonal antibody was identified that activates EMR2 G protein signaling in vitro.\",\n      \"method\": \"Yeast-based GPCR/chimeric G protein coupling assay, cAMP inhibition assay in mammalian cells, IP1 accumulation assay, NFAT reporter assay, pertussis toxin treatment\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple recombinant assay systems (yeast, mammalian) with pharmacological validation (PTX) in a single lab study\",\n      \"pmids\": [\"31969668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Mechanical activation (vibration) of mast cells expressing p.C492Y-ADGRE2 attached to dermatan sulfate triggers phospholipase C activation, transient cytosolic calcium increases, and downstream activation of PI3K and ERK1/2, mediated by Gβγ, Gαq/11, and through Gαi/o-independent mechanisms. Degranulation was dependent on PLC pathways (calcium, PKC, PI3K) and pertussis toxin-sensitive signals. Mechanoactivation also stimulated prostaglandin D2 synthesis via ERK1/2, calcium, PKC, and PI3K.\",\n      \"method\": \"Vibration stimulation of human mast cells on dermatan sulfate substrate, calcium imaging, pharmacological inhibitors of PLC/PKC/PI3K/ERK, pertussis toxin treatment, prostaglandin D2 ELISA, degranulation assay\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal pharmacological dissections of the signaling pathway with functional readouts (degranulation, PGD2), pertussis toxin validation, using physiologically relevant variant receptor on its natural ligand\",\n      \"pmids\": [\"32222457\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"EMR2/ADGRE2 contains an SGD sequence (corresponding to the RGD integrin-binding motif in CD97). Unlike CD97, EMR2 fails to induce angiogenesis or upregulate MMP-9. However, a single change of the SGD to RGD sequence in EMR2 allows it to up-regulate MMP-9 expression, leading to enhanced angiogenesis. MMP-9 promotes HUVEC proliferation, migration, and invasion by modulating VEGF, PIGF, and bFGF levels. MMP-9 expression is modulated by N-cadherin, which is upregulated by both CD97 and EMR2/RGD.\",\n      \"method\": \"Site-directed mutagenesis (SGD→RGD), in vitro endothelial tube formation assay, in ovo chick chorioallantoic membrane assay, MMP-9 expression analysis, VEGF/PIGF/bFGF measurement\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function mutagenesis with multiple functional angiogenesis readouts, single lab study\",\n      \"pmids\": [\"31594642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"EMR2 stimulation by its agonistic 2A1 monoclonal antibody activates the NLRP3 inflammasome second signal in THP-1 monocytic cells and primary monocytes via a Gα16-dependent PLC-β activation pathway, inducing downstream Akt, MAPK, NF-κB activation and Ca2+ mobilization, ultimately leading to K+ efflux.\",\n      \"method\": \"Anti-EMR2 mAb (2A1) stimulation, siRNA knockdown, pharmacological inhibitors, K+ efflux measurement, Ca2+ mobilization assay, NLRP3 inflammasome activation assay in THP-1 and primary monocytes\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA and pharmacological dissection of pathway from EMR2 to NLRP3 with multiple downstream readouts, single lab study\",\n      \"pmids\": [\"33488598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ADGRE2 activates phospholipase Cβ/protein kinase C/MEK/ERK signaling to enhance expression of AP1 transcription factor, which transcriptionally drives DUSP1 (a protein phosphatase). DUSP1 dephosphorylates Ser16 in the J-domain of co-chaperone DNAJB1, facilitating the DNAJB1-HSP70 interaction and maintenance of proteostasis in AML. Silencing ADGRE2 exerts antileukemic effects in AML cell lines and patient-derived cells in vitro, and delays AML progression in xenograft models.\",\n      \"method\": \"siRNA/shRNA knockdown, xenograft mouse models, pharmacological inhibitors of MEK/AP1/DUSP1, phosphorylation analysis (DUSP1 Ser16), co-immunoprecipitation (DNAJB1-HSP70), transcriptional reporter assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pathway mechanistically dissected from receptor to proteostasis via multiple orthogonal methods (KD, inhibitors, co-IP, phospho-analysis, xenograft), validated in patient-derived cells and in vivo\",\n      \"pmids\": [\"39082681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CD312/ADGRE2 interacts with GNA15 (Gα15) via its transmembrane intracellular segment. CD312 knockdown reduces Treg cell proportion while increasing CTL proportion in the ALL bone marrow immune microenvironment. Overexpression of CD312 in CD3+ T cells enhances leukemia cell proliferation via phosphorylation of ERK, JNK, and p38, while GNA15 knockdown decreases this proliferative effect.\",\n      \"method\": \"Co-immunoprecipitation/affinity assay for CD312-GNA15 interaction, CD312 knockdown and overexpression, GNA15 siRNA, BrdU proliferation assay, flow cytometry for immune subsets\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct protein interaction assay (CD312-GNA15) combined with functional knockdown/overexpression and MAPK pathway analysis, single lab study\",\n      \"pmids\": [\"39656442\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ADGRE2/EMR2 is a myeloid-restricted adhesion GPCR that undergoes autocatalytic intramolecular GPS/GAIN-domain cleavage in the ER at Leu517-Ser518 (requiring a Ser/Thr/Cys at P+1), producing a non-covalent extracellular α-subunit/transmembrane β-subunit heterodimer whose subunit interaction tonically inhibits signaling; upon ligation by its extracellular EGF module 4 to chondroitin/dermatan sulfate ligands, or upon antibody-mediated activation, the subunits translocate into lipid raft microdomains where the receptor couples broadly to G proteins (primarily Gα16, Gαq/11, Gαz, Gβγ) to activate PLC-β → Ca2+/PKC → PI3K/Akt → MAPK/NF-κB cascades, driving neutrophil adhesion/migration/superoxide production, macrophage differentiation and cytokine production, monocyte NLRP3 inflammasome activation, and in AML an MEK/AP1/DUSP1/DNAJB1-HSP70 proteostasis axis; a disease-causing p.C492Y variant destabilizes the autoinhibitory α–β interaction to sensitize mast cells to mechanical (vibratory) degranulation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ADGRE2 (EMR2/CD312) is a myeloid-restricted adhesion G protein-coupled receptor of the EGF-TM7 family that links extracellular glycosaminoglycan recognition to proinflammatory signaling [#0, #2]. Its extracellular region carries five tandem EGF-like modules, and the fourth EGF module mediates Ca2+- and sulfation-dependent binding to chondroitin sulfate and the variant dermatan sulfate, defining a ligand specificity distinct from its paralog CD97/CD55 [#2, #5, #6]. The receptor matures by autocatalytic intramolecular cis-proteolysis at the His-Leu\\u2193Ser518 GPS site within the ER, an N-terminal-nucleophile-hydrolase-like reaction requiring a Ser/Thr/Cys at P+1 and the full extracellular stalk, generating a non-covalent extracellular \\u03b1-subunit/transmembrane \\u03b2-subunit heterodimer [#3, #4]. Ligation or antibody-mediated activation drives subunit translocation into lipid raft microdomains, which is required for downstream signaling and cytokine output [#9]. The activated receptor couples broadly to G proteins, including G\\u03b116 and G\\u03b1q/11, to engage a PLC-\\u03b2 \\u2192 Ca2+/PKC \\u2192 PI3K/Akt \\u2192 MAPK/NF-\\u03baB cascade [#12, #14, #15]. Functionally this potentiates neutrophil adhesion, migration, superoxide production and degranulation [#8], promotes monocyte/macrophage differentiation, cytokine secretion and NLRP3 inflammasome activation [#12, #17], and in AML sustains an MEK/ERK\\u2192AP1\\u2192DUSP1\\u2192DNAJB1-HSP70 proteostasis axis whose disruption is antileukemic [#18]. A heterozygous p.C492Y variant that destabilizes the autoinhibitory \\u03b1\\u2013\\u03b2 subunit interaction causes autosomal dominant vibratory urticaria by sensitizing mast cells to mechanical, IgE-independent degranulation [#11, #15].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established ADGRE2/EMR2 as a distinct myeloid-restricted EGF-TM7 class B GPCR, separating it from its ubiquitous paralog CD97 and asking what its ligand and function are.\",\n      \"evidence\": \"Genomic mapping, cloning, monoclonal antibody and flow cytometry on leukocytes, with ligand-binding assays showing no CD55 interaction\",\n      \"pmids\": [\"10903844\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ligand identity unknown at this stage\", \"No signaling mechanism defined\", \"Functional consequences of expression not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed the receptor exists at the cell surface as a two-subunit heterodimer (extracellular \\u03b1 + 7TM \\u03b2), establishing the architecture later linked to autoproteolysis and autoinhibition.\",\n      \"evidence\": \"Reciprocal immunoprecipitation and flow cytometry with the 2A1 mAb on primary leukocytes and cell lines\",\n      \"pmids\": [\"11994511\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism generating the heterodimer not yet defined\", \"Subunit interaction strength/regulation unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified chondroitin sulfate as the molecular ligand and localized binding to the fourth EGF module, answering what ADGRE2 recognizes extracellularly.\",\n      \"evidence\": \"Multivalent protein probes, GAG-biosynthesis-deficient CHO mutants, enzymatic GAG removal and dose-dependent inhibition\",\n      \"pmids\": [\"12829604\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological cellular source of CS ligand in vivo not defined\", \"Signaling consequence of ligation not yet measured\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defined the GPS cleavage site at Leu517-Ser518 and showed the full extracellular stalk (not the GPS motif alone) is required, with alternative splicing controlling whether cleavage occurs.\",\n      \"evidence\": \"Site-directed mutagenesis, biochemical and cell-free cleavage assays, analysis of spliced isoforms\",\n      \"pmids\": [\"12860403\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Catalytic chemistry of cleavage not yet established\", \"Functional role of cleavage in signaling unaddressed\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrated GPS proteolysis is an autocatalytic intramolecular reaction occurring in the ER, mechanistically resembling N-terminal nucleophile hydrolases.\",\n      \"evidence\": \"Mutagenesis of P+1/P-2 residues and cell-free spontaneous hydrolysis of slow-processing precursors\",\n      \"pmids\": [\"15150276\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link between cleavage and receptor activation not yet demonstrated\", \"Fate of subunits after cleavage unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extended ligand recognition to a cellular context, showing EGF4-mediated CS binding targets B cells, implying immune cell\\u2013cell interactions.\",\n      \"evidence\": \"Recombinant protein-coated beads and isoform-specific mAbs on primary leukocytes\",\n      \"pmids\": [\"15498814\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the EMR2\\u2013B cell interaction not tested\", \"In vivo relevance not established\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Connected ADGRE2 to inflammatory disease by identifying dermatan sulfate as a ligand and showing elevated EMR2 on activated macrophages/DCs in rheumatoid synovium.\",\n      \"evidence\": \"Immunohistochemistry, immunofluorescence colocalization and multivalent probe binding on synovial tissue\",\n      \"pmids\": [\"15693006\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal role in RA pathogenesis not demonstrated\", \"Downstream signaling in synovial cells not measured\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed ADGRE2 expression is dynamically regulated during myeloid differentiation and induced by LPS and IL-10, framing it as an inducible inflammatory receptor.\",\n      \"evidence\": \"Flow cytometry, qPCR and cytokine stimulation of primary myeloid cells\",\n      \"pmids\": [\"17174274\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcriptional regulators not identified\", \"Functional output of regulated expression not tested here\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Provided the first direct functional evidence that receptor ligation drives effector responses, establishing ADGRE2 as a proinflammatory neutrophil receptor.\",\n      \"evidence\": \"Anti-EMR2 antibody ligation with adhesion, migration, superoxide, degranulation assays and live imaging of receptor translocation\",\n      \"pmids\": [\"17928360\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"G protein and second-messenger pathway not defined\", \"Endogenous ligand-triggered responses not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified additional neutrophil outcomes of ligation, including suppression of LPS-induced survival and altered cytokine secretion.\",\n      \"evidence\": \"2A1 mAb ligation with apoptosis, ROS and cytokine ELISA assays\",\n      \"pmids\": [\"22035891\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab functional study with limited mechanistic depth\", \"Signaling intermediates not mapped\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linked GPS autoproteolysis to signaling by showing ligation drives subunit translocation and colocalization in lipid rafts, which is required for cytokine production.\",\n      \"evidence\": \"Lipid raft fractionation, co-IP, live imaging, GPS-mutant constructs and macrophage cytokine assays\",\n      \"pmids\": [\"22310662\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of raft-resident signaling partners not defined\", \"G protein specificity not yet resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established a Mendelian disease link, showing the p.C492Y variant destabilizes the \\u03b1\\u2013\\u03b2 interaction and causes autosomal dominant vibratory urticaria via mast cell sensitization.\",\n      \"evidence\": \"Cosegregation in two kindreds plus mast cell degranulation and subunit-interaction biochemistry\",\n      \"pmids\": [\"26841242\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream mechanotransduction signaling not yet dissected\", \"How subunit destabilization couples to force sensing unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined the canonical signaling cascade in monocytes, placing G\\u03b116 upstream of sequential Akt/ERK/JNK/NF-\\u03baB activation driving differentiation and proinflammatory mediator expression.\",\n      \"evidence\": \"Anti-EMR2 mAb stimulation with siRNA knockdown and inhibitors of pathway nodes in THP-1 cells\",\n      \"pmids\": [\"28421075\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct receptor\\u2013G\\u03b116 coupling biochemistry not shown here\", \"Endogenous ligand-driven cascade not tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Refined post-cleavage receptor biology by showing site-specific GAIN-domain N-glycosylation and an amphipathic helix control membrane association of the N-terminal fragment.\",\n      \"evidence\": \"Glycosylation-site mutagenesis, subcellular fractionation and domain deletion analysis\",\n      \"pmids\": [\"29540735\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of NTF membrane anchoring for signaling unknown\", \"Single-lab biochemical study\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Confirmed ADGRE2 is a functional GPCR with broad G protein coupling, including G\\u03b116 and PTX-insensitive G\\u03b1z, distinguishing it from CD97's narrower coupling.\",\n      \"evidence\": \"Yeast chimeric G protein assay, cAMP inhibition, IP1 accumulation and NFAT reporter with pertussis toxin\",\n      \"pmids\": [\"31969668\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Coupling tested with truncated/activated forms, not native ligand\", \"Physiological G protein usage in primary cells not confirmed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Mechanistically dissected the disease pathway, showing variant-receptor mechanoactivation on dermatan sulfate triggers PLC/Ca2+/PKC/PI3K/ERK signaling and PGD2 synthesis driving degranulation.\",\n      \"evidence\": \"Vibration stimulation of mast cells on dermatan sulfate with calcium imaging, pathway inhibitors, pertussis toxin and PGD2 ELISA\",\n      \"pmids\": [\"32222457\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct force-sensing molecular event not resolved\", \"Contribution of specific G\\u03b1 subunits to mechanosignaling only partially defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Used SGD\\u2192RGD swap to show ADGRE2 lacks the integrin motif of CD97 and does not promote angiogenesis, clarifying functional divergence from its paralog.\",\n      \"evidence\": \"Site-directed mutagenesis with endothelial tube formation, CAM assay and MMP-9/VEGF analysis\",\n      \"pmids\": [\"31594642\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous angiogenic role of wild-type EMR2 remains negative/uncharacterized\", \"Single-lab gain-of-function study\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended the G\\u03b116/PLC-\\u03b2 cascade to innate immune activation, showing EMR2 stimulation licenses the NLRP3 inflammasome second signal via Akt/MAPK/NF-\\u03baB, Ca2+ and K+ efflux.\",\n      \"evidence\": \"2A1 mAb stimulation with siRNA, inhibitors, K+ efflux and Ca2+ assays in THP-1 and primary monocytes\",\n      \"pmids\": [\"33488598\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous ligand triggering of inflammasome not tested\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed a pro-leukemic role in AML, linking the PLC-\\u03b2/PKC/MEK/ERK\\u2192AP1\\u2192DUSP1 axis to DNAJB1-HSP70 chaperone function and proteostasis maintenance.\",\n      \"evidence\": \"siRNA/shRNA knockdown, MEK/AP1/DUSP1 inhibitors, DUSP1 Ser16 phospho-analysis, DNAJB1-HSP70 co-IP and xenograft models in patient-derived AML cells\",\n      \"pmids\": [\"39082681\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream ligand/activation trigger in AML cells not defined\", \"Whether autoproteolysis is required for the leukemic axis untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified a direct intracellular interaction with G\\u03b115/GNA15 and a T-cell-associated pro-leukemic effect in ALL, supporting G protein engagement and microenvironmental immune modulation.\",\n      \"evidence\": \"Co-IP/affinity assay for CD312-GNA15, knockdown/overexpression, BrdU proliferation and flow cytometry of immune subsets\",\n      \"pmids\": [\"39656442\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP for the CD312-GNA15 interaction\", \"Mechanism of T-cell-mediated leukemia support beyond MAPK phosphorylation unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How endogenous chondroitin/dermatan sulfate ligation, mechanical force, and subunit dissociation are integrated into a unified activation mechanism, and whether autoproteolysis is required across all disease contexts, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the activated ligand-bound receptor\", \"Force-sensing molecular event not defined\", \"Native-ligand-driven (vs antibody-driven) signaling incompletely characterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [12, 14, 17]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [2, 5, 8]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 8, 9]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [8, 12, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [12, 14, 15]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [11, 15, 18]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [18]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"GNA15\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}