{"gene":"CD55","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":1996,"finding":"CD55 (DAF) was identified as the cellular ligand for the seven-span transmembrane receptor CD97; the interaction was mapped to the NH2-terminal short consensus repeat (SCR) of CD55, and erythrocytes lacking CD55 (from PNH or Inab phenotype patients) failed to adhere to CD97 transfectants, establishing specificity.","method":"Cell adhesion assay with CD97-transfected COS cells, blocking mAb against CD55 SCR1, and CD55-null erythrocytes as negative controls","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — reciprocal functional validation with transfectants, blocking antibody, and disease-derived null cells; replicated in multiple follow-up studies","pmids":["9064337"],"is_preprint":false},{"year":1994,"finding":"CD55 (DAF) functions as the receptor mediating attachment and infection by multiple echovirus serotypes; anti-DAF mAbs blocked echovirus 7 attachment, phospholipase C treatment (removing GPI-anchored proteins) abolished binding, and CHO cells expressing human DAF gained the ability to bind echovirus.","method":"Anti-DAF mAb blocking assay, phosphatidylinositol-specific phospholipase C treatment, and DAF-transfected CHO cell binding assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (mAb block, enzymatic GPI removal, gain-of-function transfection) in a single study","pmids":["7517044"],"is_preprint":false},{"year":1996,"finding":"CD55 (DAF) is the HeLa cell receptor for Enterovirus 70 (EV70); a blocking mAb (EVR1) directed against CD55 inhibited EV70 binding and infection, and stable expression of human DAF in NIH 3T3 cells conferred susceptibility to EV70 replication.","method":"mAb blocking assay, immunoprecipitation identifying ~75 kDa GPI-anchored glycoprotein, and stable DAF-transfected cell infection assay","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 — gain-of-function transfection plus mAb blocking plus biochemical identification; multiple orthogonal methods","pmids":["8764022"],"is_preprint":false},{"year":1998,"finding":"The CD55-binding site on CD97 requires at least three tandemly linked EGF domains; deletion mutants of CD97 lacking individual EGF domains abolished CD55 binding, and mAbs against EGF domain 1 and removal of Ca2+ (required by EGF2 and EGF5 binding sites) blocked the interaction. Larger CD97 isoforms with additional EGF domains had significantly lower affinity for CD55, indicating that alternative splicing regulates ligand specificity.","method":"EGF domain deletion mutants in binding assay, mAb blocking, Ca2+ chelation experiments","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1–2 — systematic mutagenesis/deletion of receptor domains with functional binding readout, multiple orthogonal approaches","pmids":["9603477"],"is_preprint":false},{"year":1991,"finding":"CD55 and CD59 co-immunoprecipitate with a common 80-kDa glycoprotein and (glyco)lipids in detergent-resistant complexes, and these complexes contain an associated protein kinase activity, suggesting CD55 is part of a GPI-anchored signaling complex.","method":"Co-immunoprecipitation from detergent lysates of HPB-ALL cell line, SDS-PAGE analysis, protein kinase activity assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 3 — single co-IP with kinase activity readout; not independently replicated with orthogonal structural methods","pmids":["1715364"],"is_preprint":false},{"year":1994,"finding":"CD55's complement regulatory activity is mediated through its third short consensus repeat (SCR3), and the GPI anchor connects CD55 with associated tyrosine kinases on the inner leaflet, enabling signaling in addition to complement decay acceleration.","method":"Structural domain analysis, functional complement assays, and review of biochemical fractionation studies","journal":"The Journal of laboratory and clinical medicine","confidence":"Medium","confidence_rationale":"Tier 3 — domain mapping and functional complement assay, but mechanistic signaling link inferred rather than directly demonstrated","pmids":["7511675"],"is_preprint":false},{"year":1999,"finding":"Mouse CD55 (both GPI-anchored and transmembrane isoforms) inhibits C3b deposition and protects cells from complement lysis; CD55 knockout mouse erythrocytes failed to adhere to mouse CD97 transfectants, and the CD97–CD55 interaction is species-restrictive (human erythrocytes did not bind mouse CD97).","method":"Stable transfection of DAF isoforms in CHO cells, C3b deposition assay, haemolytic assay, adhesion assay with DAF knockout mouse erythrocytes","journal":"Immunology","confidence":"High","confidence_rationale":"Tier 1–2 — gain-of-function reconstitution in CHO cells with functional complement assays plus loss-of-function (knockout) adhesion assay","pmids":["10540231"],"is_preprint":false},{"year":1999,"finding":"Multiple mouse DAF isoforms generated by alternative splicing (from two genes Daf-GPI and Daf-TM) were identified; both TM and GPI-anchored forms were stably expressed in CHO cells and conferred protection from C3b deposition and complement-mediated lysis, demonstrating functional activity of distinct isoforms.","method":"Molecular cloning, Northern blot, stable transfection in CHO cells, C3b deposition assay, cell lysis assay, soluble recombinant DAF haemolytic inhibition assay","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple functional complement assays in transfected cells","pmids":["10417349"],"is_preprint":false},{"year":1998,"finding":"Cardiovirulent coxsackievirus B3 (CVB3) uses CD55 as an attachment receptor on HeLa cells; anti-DAF mAbs directed against SCR2 and SCR3 most effectively blocked binding and infection, and virus binding was associated with CD55 downregulation at the cell surface. CVB3 did not interact with structurally related complement regulators CD35, CD46, Factor H, or C4BP.","method":"Anti-DAF mAb blocking, phospholipase C treatment to remove GPI-anchored proteins, flow cytometry of CD55 surface expression, competitive binding assays","journal":"Virology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (mAb block, enzymatic removal, flow cytometry) with domain mapping; receptor specificity established by negative controls","pmids":["9601501"],"is_preprint":false},{"year":2002,"finding":"A DAF-using echovirus 11 (EV11) strain enters cells via lipid rafts in a cholesterol- and cytoskeleton-dependent manner. DAF usage by EV11 enables the virus to associate with lipid raft components (Triton X-100 resistant fractions), and this raft-dependent entry pathway is post-binding but prior to RNA uncoating.","method":"Pharmacological inhibitors of endocytosis pathways, RNA transfection and virus-binding assays, confocal microscopy, co-purification of virus with lipid raft fractions after Triton X-100 extraction","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (pharmacological, biochemical fractionation, imaging) dissecting the entry mechanism","pmids":["12186914"],"is_preprint":false},{"year":2005,"finding":"CD55 expression is induced by hypoxia on the apical membrane of mucosal epithelial cells via a HIF binding site in the CD55 promoter (~200 bp region), and overexpression of CD55 in non-hypoxic epithelia promotes apical clearance of neutrophils; peptide mimetics of the PMN-binding site on CD55 blocked this clearance.","method":"Hypoxia gene expression screen, CD55 mRNA/protein induction assay, CD55 transfection in normoxic cells, PMN clearance assay, peptide mimetic blocking, promoter-reporter assay with HIF binding site mutation","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods: transcriptional mapping, gain-of-function, and peptide blocking with defined functional readout","pmids":["15923405"],"is_preprint":false},{"year":2003,"finding":"CD55 is part of the LPS receptor complex and contributes to LPS signaling; CD55 transfection in CHO cells conferred NF-κB translocation after LPS/lipid A stimulation, co-immunoprecipitation showed CD55–lipid A interaction, FRET demonstrated CD55–lipid A proximity in human monocytes, and LPS-induced clustering of CD55 with CD11/CD18 was observed. MAP kinase pathways (p38, JNK, ERK) are activated downstream and can be blocked at TLR4.","method":"CHO cell transfection with human CD55, NF-κB reporter assay, co-immunoprecipitation with anti-lipid A mAb, FRET analysis in human monocytes, MAP kinase phosphorylation assays, TLR4 inhibition","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (co-IP, FRET, gain-of-function transfection, signaling pathway assays) in a single study","pmids":["12731067"],"is_preprint":false},{"year":2010,"finding":"Deletion of CD55 in mouse models of rheumatoid arthritis (collagen-induced and K/BxN serum-transfer models) resulted in decreased arthritis rather than the disease aggravation seen in other inflammatory models, indicating that CD55–CD97 interaction on synoviocytes/macrophages promotes joint inflammation.","method":"CD55 knockout and CD97 knockout mice in two arthritis models, clinical scoring, immunohistochemistry","journal":"Arthritis and rheumatism","confidence":"High","confidence_rationale":"Tier 2 — clean genetic KO with defined disease phenotype in two independent models; both CD55 and CD97 KO phenocopied each other","pmids":["20131275"],"is_preprint":false},{"year":2015,"finding":"CD55 is an essential host factor required for P. falciparum invasion of erythrocytes; CD55-null red blood cells derived from hematopoietic stem cells were refractory to invasion by all P. falciparum isolates tested because parasites failed to properly attach to the erythrocyte surface.","method":"Forward genetic screen using cultured RBCs from hematopoietic stem cells, CD55-null erythrocytes in parasite invasion assay","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function in relevant primary human cell type with clear mechanistic readout (failure of parasite attachment); forward genetic screen design","pmids":["25954012"],"is_preprint":false},{"year":2017,"finding":"Biallelic loss-of-function mutations in CD55 cause loss of CD55 expression, leading to increased complement activation with surface deposition of complement and generation of soluble C5a on T lymphocytes, defective costimulatory function, and defective cytokine modulation. Genetic reconstitution of CD55 or treatment with a complement-inhibitory antibody reversed abnormal complement activation.","method":"Whole-exome sequencing, flow cytometry of complement deposition, complement activation assays on patient T lymphocytes, exogenous CD55 expression rescue, complement-inhibitory antibody rescue","journal":"The New England journal of medicine","confidence":"High","confidence_rationale":"Tier 2 — human disease genetics combined with functional cellular assays and genetic/pharmacologic rescue; multiple orthogonal methods","pmids":["28657829"],"is_preprint":false},{"year":2017,"finding":"CD55 regulates cancer stem cell self-renewal and cisplatin resistance in a complement-independent manner via lipid raft localization; CD55 activates ROR2/JNK signaling to control self-renewal and core pluripotency genes, and in parallel activates LCK (lymphocyte-specific protein tyrosine kinase) signaling to induce DNA repair genes and cisplatin resistance.","method":"Comparative CSC/non-CSC transcriptomic analysis, lipid raft fractionation, ROR2/JNK pathway inhibition, LCK inhibition with saracatinib, KD/KO with self-renewal and chemoresistance phenotype readouts","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — complement-independent signaling mechanism established by lipid raft fractionation, pathway-specific inhibitors, and defined downstream gene targets with functional phenotypes","pmids":["28838952"],"is_preprint":false},{"year":2013,"finding":"HCV infection upregulates CD55 expression on hepatocytes via HCV core protein-mediated enhancement of CD55 promoter activity dependent on CREB and SP-1 binding sites; IL-6 further augments this induction. CD55 associates with HCV particles purified by sucrose density gradient, and CD55-blocking antibodies with complement inhibited HCV infection.","method":"CD55 mRNA/protein assay in HCV-infected hepatocytes, luciferase-based promoter activity assay with CREB/SP-1 site mutation, sucrose density gradient ultracentrifugation of HCV particles, polyclonal anti-CD55 capture of HCV, blocking antibody infection assay","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 — promoter mutagenesis, biochemical co-purification of CD55 with virus, and functional infection blocking; multiple orthogonal methods","pmids":["23658447"],"is_preprint":false},{"year":2016,"finding":"HCV infection induces synthesis of a secreted CD55 isoform (sCD55) via alternative splicing; conditioned medium from HCV-infected cells inhibits C3 convertase activity and complement-dependent cytolysis in a CD55-dependent manner, implicating sCD55 in complement evasion in the infected microenvironment.","method":"RT-PCR for sCD55 isoform, C3 convertase activity assay with conditioned medium, complement-dependent cytolysis assay, CD55-blocking antibody reversal","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — functional assays demonstrating sCD55-mediated complement inhibition, but mechanistic details of splicing regulation not fully defined","pmids":["27357152"],"is_preprint":false},{"year":2020,"finding":"ST3GAL1-mediated O-linked sialylation of CD55 protects cancer cells from complement-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity; ST3GAL1 silencing shifted CD55 O-glycan profile from disialylated core 2 to nonsialylated/monosialylated forms, increasing C3 deposition on breast cancer cells.","method":"ST3GAL1 siRNA knockdown, tandem mass spectrometry of N- and O-linked oligosaccharides released from CD55, C3 deposition assay, complement-mediated lysis assay, ADCC assay","journal":"Cancer immunology research","confidence":"High","confidence_rationale":"Tier 1–2 — direct structural glycan analysis combined with functional complement assays; multiple orthogonal methods in a single study","pmids":["33177111"],"is_preprint":false},{"year":2012,"finding":"Activation of dsRNA sensors TLR3, MDA5, and RIG-I in fibroblast-like synoviocytes upregulates CD55 expression, which enhances the capacity of fibroblasts to bind CD97-loaded beads; this upregulation was blocked by anti-CD55 antibodies, linking innate immune dsRNA sensing to the CD55–CD97 adhesion axis.","method":"Cytokine/TLR ligand stimulation of FLS, flow cytometry of CD55 expression, CD97-loaded bead binding assay, anti-CD55 antibody blocking","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 — functional bead binding assay with antibody blocking establishes upregulation-to-function link, but mechanism of transcriptional induction not fully delineated","pmids":["22590509"],"is_preprint":false},{"year":2007,"finding":"Neurosteroids progesterone and allopregnanolone enhance CD55 production following brain contusion injury in rats, suggesting that steroid-mediated induction of CD55 is a mechanism by which these steroids reduce complement convertase activity and neuroinflammation.","method":"Rat cortical contusion model, CD55 protein quantification after progesterone/allopregnanolone treatment","journal":"Neuroscience letters","confidence":"Low","confidence_rationale":"Tier 3 — single in vivo measurement; correlation between treatment and CD55 induction without direct mechanistic dissection","pmids":["17826908"],"is_preprint":false},{"year":2010,"finding":"Recombinant human CD55 (DAF) protects primary cultured neuronal cells from chemical hypoxia by inhibiting complement activation (reducing C3a accumulation and MAC formation) and by decreasing activated Src kinase (pTyr416-Src), caspase-9, and caspase-3 activity, reducing neuronal apoptosis and dendritic spine loss.","method":"Primary cortical neuron culture, NaCN hypoxia model, recombinant DAF treatment, TUNEL assay, MTT assay, dendritic spine counting, immunofluorescence for complement components and MAC, Western blot for activated caspases and Src","journal":"Journal of neuroinflammation","confidence":"Medium","confidence_rationale":"Tier 2 — exogenous recombinant protein treatment with multiple functional and biochemical readouts; mechanism partially established","pmids":["20380727"],"is_preprint":false},{"year":2002,"finding":"CD55 is overexpressed on tumor cells and is upregulated on endothelial cells by VEGF at the cell surface and in the extracellular matrix (ECM); MMP-7 releases intact, functionally active CD55 from ECM (unlike papain which degrades it or collagenase which fails to release it), suggesting a role for soluble CD55 in protecting tumor microenvironment from complement.","method":"VEGF treatment of HUVEC cells, immunoassay of cell surface and ECM CD55, metalloproteinase treatment assays, functional complement assay of released CD55","journal":"Tissue antigens","confidence":"Medium","confidence_rationale":"Tier 2–3 — functional release and complement-inhibitory activity assay of ECM-derived CD55; MMP-7 specificity established by comparison with other proteases","pmids":["12445304"],"is_preprint":false},{"year":2022,"finding":"EGFR/Wnt/β-catenin signaling induces lncRNA LINC00973 expression, which sponges CD55-targeting miR-216b, resulting in upregulated CD55 expression that suppresses complement activation and CD8+ T cell activation in lung cancer; anti-CD55/CD59 antibody treatment or LINC00973 promoter mutation activated complement and CD8+ T cells, and combined anti-CD55/CD59 with anti-PD-1 showed synergistic tumor inhibition.","method":"β-catenin ChIP for LINC00973 promoter, miRNA sponging assay, LINC00973 promoter mutation, anti-CD55/CD59 neutralizing antibody, complement activation assay, CD8+ T cell activation assay, tumor growth assay","journal":"Nature cancer","confidence":"High","confidence_rationale":"Tier 2 — comprehensive pathway dissection from upstream signaling to CD55 regulation to functional complement/immune evasion outcome; multiple orthogonal methods","pmids":["36271172"],"is_preprint":false},{"year":2016,"finding":"Parainfluenza virus 5 (PIV5) incorporates functional CD55 into virions, and virion-incorporated CD55 (but not CD46) confers high resistance to complement-mediated neutralization; PIV5 infection upregulates cell surface CD55 (further enhanced by TNF-α), and virus derived from cells with higher CD55 levels is more resistant to complement neutralization.","method":"Complement neutralization assay with virus containing CD55 alone, CD46 alone, or both, flow cytometry of CD55 surface levels, virus derived from cells with modulated CD55 levels","journal":"Virology","confidence":"High","confidence_rationale":"Tier 2 — comparative functional assay with defined viral particles; mechanism of complement evasion directly attributed to virion-incorporated CD55","pmids":["27505156"],"is_preprint":false}],"current_model":"CD55 (DAF) is a GPI-anchored complement regulatory protein that accelerates the decay of C3/C5 convertases via its SCR domains (particularly SCR3), and additionally functions as a cellular ligand for the adhesion receptor CD97 (via CD55's SCR1 and Ca2+-dependent EGF domains on CD97), as a receptor for multiple enteroviruses (echoviruses, EV70, CVB3) through its SCR2-3 domains, as an essential erythrocyte surface factor required for P. falciparum attachment, as a component of the LPS receptor complex linked to NF-κB and MAP kinase signaling, and—in a complement-independent context—as a lipid raft-localized signaling node that activates ROR2/JNK and LCK pathways to drive cancer stem cell self-renewal and chemoresistance; its activity is further modulated by ST3GAL1-mediated O-sialylation, HIF-dependent transcriptional induction at sites of inflammation, and virus-induced upregulation for immune evasion."},"narrative":{"teleology":[{"year":1991,"claim":"Whether GPI-anchored complement regulators participate in signaling complexes was unknown; co-immunoprecipitation of CD55 and CD59 with an 80-kDa glycoprotein bearing kinase activity established that CD55 resides in detergent-resistant complexes with signaling potential.","evidence":"Co-immunoprecipitation from HPB-ALL cell lysates with kinase activity assay","pmids":["1715364"],"confidence":"Medium","gaps":["Single co-IP without reciprocal validation or identification of the 80-kDa partner","No downstream signaling pathway delineated","Functional consequence of kinase activity not tested"]},{"year":1994,"claim":"The question of whether CD55 has functions beyond complement regulation was answered when it was identified as the cellular receptor for multiple echovirus serotypes, with GPI-anchored presentation essential for virus binding.","evidence":"Anti-DAF mAb blocking, PI-PLC treatment, and gain-of-function DAF-transfected CHO cell binding assay","pmids":["7517044"],"confidence":"High","gaps":["Viral entry mechanism downstream of CD55 binding not resolved","Whether CD55 serves as entry receptor versus attachment receptor not distinguished"]},{"year":1994,"claim":"Mapping of complement-regulatory activity to SCR3 established the structural basis for decay-accelerating function and separated it from the GPI anchor's potential signaling role.","evidence":"Domain analysis and functional complement assays","pmids":["7511675"],"confidence":"Medium","gaps":["Mechanistic signaling link through the GPI anchor inferred but not directly demonstrated","Structural basis of SCR3 interaction with convertases not resolved at atomic level"]},{"year":1996,"claim":"CD55 was identified as the ligand for the seven-span transmembrane receptor CD97, mapping the interaction to SCR1 and establishing a cell adhesion function distinct from complement regulation and virus binding.","evidence":"Cell adhesion assay with CD97-transfected COS cells, anti-SCR1 blocking mAb, and CD55-null erythrocytes from PNH/Inab patients","pmids":["9064337"],"confidence":"High","gaps":["Downstream signaling through CD97 upon CD55 engagement not characterized","In vivo physiological consequence of the interaction not tested at this point"]},{"year":1996,"claim":"Extension of CD55's virus receptor role to enterovirus 70 demonstrated that diverse picornaviruses convergently exploit CD55 for cell entry.","evidence":"mAb blocking and gain-of-function DAF-transfected NIH 3T3 cells conferring EV70 susceptibility","pmids":["8764022"],"confidence":"High","gaps":["Molecular determinants on CD55 engaged by EV70 not mapped at domain level"]},{"year":1998,"claim":"CVB3 was shown to use CD55 SCR2–SCR3 for attachment, and the CD97 EGF domain requirements for CD55 binding were mapped, together defining two distinct interaction surfaces on CD55.","evidence":"Anti-DAF domain-specific mAb blocking for CVB3; EGF domain deletion mutants and Ca²⁺ chelation for CD97 binding","pmids":["9601501","9603477"],"confidence":"High","gaps":["Whether CVB3 requires a coreceptor for entry not resolved","Structural basis of CD55 SCR engagement by virus versus CD97 not compared"]},{"year":1999,"claim":"Cloning of mouse DAF isoforms (GPI-anchored and transmembrane) and demonstration that both protect cells from complement confirmed conservation and showed the CD97–CD55 interaction is species-restrictive.","evidence":"Stable transfection of GPI and TM isoforms in CHO cells with C3b deposition and hemolytic assays; DAF KO mouse erythrocyte adhesion assay","pmids":["10540231","10417349"],"confidence":"High","gaps":["Physiological role of the TM isoform versus GPI isoform not distinguished in vivo","Species restriction mechanism not structurally explained"]},{"year":2002,"claim":"Two studies established CD55's role in the tumor microenvironment: DAF-using echovirus entry occurs through lipid rafts in a cholesterol-dependent manner, and VEGF-induced CD55 in the extracellular matrix is released by MMP-7 as a functional soluble complement inhibitor.","evidence":"Lipid raft fractionation and pharmacological inhibition for EV11 entry; VEGF treatment of HUVECs and MMP-7 release assay with complement functional readout","pmids":["12186914","12445304"],"confidence":"High","gaps":["Whether raft localization of CD55 is required for all enterovirus serotypes not tested","In vivo relevance of MMP-7-released soluble CD55 not demonstrated"]},{"year":2003,"claim":"CD55 was shown to be a component of the LPS receptor complex, with direct lipid A binding triggering NF-κB translocation and MAP kinase activation, expanding CD55's role to innate immune signaling.","evidence":"CHO cell transfection with NF-κB reporter, co-IP of CD55–lipid A, FRET in human monocytes, MAP kinase phosphorylation assays","pmids":["12731067"],"confidence":"High","gaps":["Whether CD55 signals independently of TLR4 or functions only as a co-receptor not resolved","Stoichiometry of CD55 in the LPS receptor complex unknown"]},{"year":2005,"claim":"Hypoxia-induced CD55 expression via a HIF-responsive promoter element was shown to promote apical neutrophil clearance from mucosal epithelia, linking tissue oxygen sensing to complement regulation at inflamed surfaces.","evidence":"Hypoxia gene expression screen, promoter-reporter with HIF site mutation, CD55 overexpression and PMN clearance assay with peptide mimetic blocking","pmids":["15923405"],"confidence":"High","gaps":["Identity of the PMN surface receptor engaging CD55 during clearance not defined","Whether HIF1α or HIF2α drives CD55 induction not distinguished"]},{"year":2010,"claim":"Genetic deletion of CD55 in two independent arthritis models unexpectedly attenuated rather than exacerbated disease, establishing that the CD55–CD97 adhesion axis promotes joint inflammation in vivo.","evidence":"CD55 KO and CD97 KO mice in collagen-induced and K/BxN serum-transfer arthritis, clinical scoring, immunohistochemistry","pmids":["20131275"],"confidence":"High","gaps":["Downstream signaling through CD97 in synoviocytes/macrophages not characterized","Whether complement-regulatory loss in KO mice partially counteracts the anti-inflammatory effect not assessed"]},{"year":2013,"claim":"HCV was found to upregulate CD55 transcription via core protein–driven CREB/SP-1 promoter activation and to physically incorporate CD55 into virion particles, establishing virus-directed exploitation of CD55 for complement evasion.","evidence":"Promoter-reporter mutagenesis, sucrose gradient co-purification of CD55 with HCV, anti-CD55 blocking infection assay","pmids":["23658447"],"confidence":"High","gaps":["Whether CD55 incorporation into HCV particles is passive or actively selected not determined"]},{"year":2015,"claim":"A forward genetic screen identified CD55 as an essential host factor for P. falciparum erythrocyte invasion, demonstrating that CD55-null red blood cells are refractory to parasite attachment.","evidence":"Forward genetic screen using cultured CD55-null erythrocytes derived from hematopoietic stem cells, parasite invasion assay","pmids":["25954012"],"confidence":"High","gaps":["Parasite ligand that engages CD55 not identified","Whether CD55's role is direct binding or membrane organization not resolved"]},{"year":2016,"claim":"Two discoveries revealed virus-directed CD55 exploitation: PIV5 incorporates functional CD55 into virions conferring complement resistance, and HCV infection induces a secreted CD55 splice isoform (sCD55) that inhibits C3 convertase in the extracellular milieu.","evidence":"Complement neutralization assay with PIV5 virions; RT-PCR for sCD55 isoform and C3 convertase/cytolysis assays with conditioned medium","pmids":["27505156","27357152"],"confidence":"High","gaps":["Splicing regulatory mechanism for sCD55 generation not defined","Whether sCD55 and virion-incorporated CD55 differ functionally not compared"]},{"year":2017,"claim":"Biallelic CD55 loss-of-function mutations were shown to cause CHAPLE syndrome with uncontrolled complement activation on T cells, and separately, complement-independent lipid raft–localized CD55 was found to activate ROR2/JNK and LCK pathways driving cancer stem cell self-renewal and chemoresistance.","evidence":"Whole-exome sequencing with functional rescue for CHAPLE; transcriptomic comparison of CSC/non-CSC with lipid raft fractionation, ROR2/JNK and LCK inhibition for cancer signaling","pmids":["28657829","28838952"],"confidence":"High","gaps":["How CD55 activates ROR2 in the absence of complement ligands not mechanistically resolved","Whether CHAPLE disease severity correlates with residual CD55 activity not studied across genotypes"]},{"year":2020,"claim":"ST3GAL1-mediated O-sialylation was shown to modulate CD55's complement-protective function, with disialylated core 2 O-glycans required for full inhibition of C3 deposition on cancer cells.","evidence":"ST3GAL1 siRNA knockdown, tandem mass spectrometry of CD55 glycans, C3 deposition and complement lysis assays in breast cancer cells","pmids":["33177111"],"confidence":"High","gaps":["Which specific O-glycosylation sites on CD55 are critical not mapped","Whether sialylation affects CD55's non-complement functions (CD97 binding, virus receptor) not tested"]},{"year":2022,"claim":"An EGFR/Wnt/β-catenin–LINC00973–miR-216b regulatory axis was shown to upregulate CD55 in lung cancer, suppressing both complement activation and CD8⁺ T cell responses; combined anti-CD55/CD59 with anti-PD-1 produced synergistic tumor inhibition.","evidence":"β-catenin ChIP, miRNA sponging assay, LINC00973 promoter mutation, anti-CD55/CD59 antibody with complement and T cell activation assays, in vivo tumor growth","pmids":["36271172"],"confidence":"High","gaps":["Whether this regulatory axis operates in cancer types beyond lung cancer not tested","Direct contribution of CD55 versus CD59 to immune evasion not individually quantified in the combination treatment"]},{"year":null,"claim":"The parasite ligand engaging CD55 during P. falciparum invasion remains unidentified, the structural basis of CD55's complement-independent signaling through ROR2 is unresolved, and whether post-translational modifications (sialylation, GPI remodeling) differentially regulate CD55's distinct functions (complement regulation, CD97 binding, virus entry, parasite attachment) has not been systematically addressed.","evidence":"","pmids":[],"confidence":"Low","gaps":["P. falciparum ligand for CD55 unknown","Atomic-resolution structure of CD55 in complex with C3 convertase not available","Systematic comparison of glycan requirements across CD55's multiple functions not performed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5,6,7,14,17,18]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,3,12]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[1,2,8]},{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[0,6]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,2,6,8,10,13,14,15,24]},{"term_id":"GO:0031012","term_label":"extracellular matrix","supporting_discovery_ids":[22]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[17,22]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,6,7,14,18,23]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[11,15,23]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[14,23]}],"complexes":["LPS receptor complex"],"partners":["CD97","CD59","ROR2","LCK","ST3GAL1","TLR4"],"other_free_text":[]},"mechanistic_narrative":"CD55 (decay-accelerating factor, DAF) is a GPI-anchored complement regulatory glycoprotein that accelerates the decay of C3/C5 convertases through its short consensus repeat (SCR) domains—particularly SCR3—thereby protecting host cells from autologous complement attack; biallelic loss-of-function mutations cause uncontrolled complement deposition on lymphocytes, leading to the CHAPLE syndrome of protein-losing enteropathy [PMID:28657829, PMID:7511675]. Beyond complement regulation, CD55 serves as a multifunctional surface receptor: it is the cellular attachment factor for echoviruses, enterovirus 70, and coxsackievirus B3 (engaging SCR2–SCR3) [PMID:7517044, PMID:8764022, PMID:9601501], a ligand for the adhesion receptor CD97 (via SCR1) whose interaction promotes leukocyte adhesion and joint inflammation [PMID:9064337, PMID:20131275], and an essential erythrocyte surface determinant required for P. falciparum invasion [PMID:25954012]. In a complement-independent context, lipid raft–localized CD55 activates ROR2/JNK and LCK signaling pathways to drive cancer stem cell self-renewal and chemoresistance, while its surface abundance is regulated transcriptionally by HIF under hypoxia, by EGFR/Wnt/β-catenin–LINC00973–miR-216b axis in tumors, and post-translationally by ST3GAL1-mediated O-sialylation that enhances complement-protective activity [PMID:28838952, PMID:15923405, PMID:36271172, PMID:33177111]."},"prefetch_data":{"uniprot":{"accession":"P08174","full_name":"Complement decay-accelerating factor","aliases":[],"length_aa":381,"mass_kda":41.4,"function":"This protein recognizes C4b and C3b fragments that condense with cell-surface hydroxyl or amino groups when nascent C4b and C3b are locally generated during C4 and c3 activation. Interaction of daf with cell-associated C4b and C3b polypeptides interferes with their ability to catalyze the conversion of C2 and factor B to enzymatically active C2a and Bb and thereby prevents the formation of C4b2a and C3bBb, the amplification convertases of the complement cascade (PubMed:7525274). Inhibits complement activation by destabilizing and preventing the formation of C3 and C5 convertases, which prevents complement damage (PubMed:28657829) (Microbial infection) Acts as a receptor for Coxsackievirus A21, coxsackieviruses B1, B3 and B5 (Microbial infection) Acts as a receptor for Human enterovirus 70 and D68 (Probable) (Microbial infection) Acts as a receptor for Human echoviruses 6, 7, 11, 12, 20 and 21","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P08174/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CD55","classification":"Not 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disease.","date":"2005","source":"Immunohematology","url":"https://pubmed.ncbi.nlm.nih.gov/15954803","citation_count":24,"is_preprint":false},{"pmid":"18930062","id":"PMC_18930062","title":"Molecular cloning and DNA binding characterization of DAF-16 orthologs from Ancylostoma hookworms.","date":"2008","source":"International journal for parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/18930062","citation_count":24,"is_preprint":false},{"pmid":"32901024","id":"PMC_32901024","title":"The precursor of PI(3,4,5)P3 alleviates aging by activating daf-18(Pten) and independent of daf-16.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32901024","citation_count":23,"is_preprint":false},{"pmid":"7514063","id":"PMC_7514063","title":"Distribution of C3-step regulatory proteins of the complement system, CD35 (CR1), CD46 (MCP), and CD55 (DAF), in hematological malignancies.","date":"1994","source":"Leukemia & lymphoma","url":"https://pubmed.ncbi.nlm.nih.gov/7514063","citation_count":21,"is_preprint":false},{"pmid":"34798183","id":"PMC_34798183","title":"Barley β-glucan resist oxidative stress of Caenorhabditis elegans via daf-2/daf-16 pathway.","date":"2021","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/34798183","citation_count":20,"is_preprint":false},{"pmid":"18443552","id":"PMC_18443552","title":"Reduction of CD55 and/or CD59 in red blood cells of patients with HIV infection.","date":"2008","source":"Medical science monitor : international medical journal of experimental and clinical research","url":"https://pubmed.ncbi.nlm.nih.gov/18443552","citation_count":20,"is_preprint":false},{"pmid":"28900141","id":"PMC_28900141","title":"Dianxianning improved amyloid β-induced pathological characteristics partially through DAF-2/DAF-16 insulin like pathway in transgenic C. elegans.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28900141","citation_count":20,"is_preprint":false},{"pmid":"27505156","id":"PMC_27505156","title":"Parainfluenza virus 5 upregulates CD55 expression to produce virions with enhanced resistance to complement-mediated neutralization.","date":"2016","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/27505156","citation_count":19,"is_preprint":false},{"pmid":"11840345","id":"PMC_11840345","title":"Upregulation of DAF (CD55) on orbital fibroblasts by cytokines. Differential effects of TNF-beta and TNF-alpha.","date":"2001","source":"Current eye research","url":"https://pubmed.ncbi.nlm.nih.gov/11840345","citation_count":19,"is_preprint":false},{"pmid":"22258276","id":"PMC_22258276","title":"Bacterial diversity in Cr(VI) and Cr(III)-contaminated industrial wastewaters.","date":"2012","source":"Extremophiles : life under extreme conditions","url":"https://pubmed.ncbi.nlm.nih.gov/22258276","citation_count":19,"is_preprint":false},{"pmid":"24820829","id":"PMC_24820829","title":"Cytogenomics of hexavalent chromium (Cr 6+) exposed cells: a comprehensive review.","date":"2014","source":"The Indian journal of medical research","url":"https://pubmed.ncbi.nlm.nih.gov/24820829","citation_count":18,"is_preprint":false},{"pmid":"29788264","id":"PMC_29788264","title":"MPK-1/ERK pathway regulates DNA damage response during development through DAF-16/FOXO.","date":"2018","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29788264","citation_count":18,"is_preprint":false},{"pmid":"27357152","id":"PMC_27357152","title":"Distinct CD55 Isoform Synthesis and Inhibition of Complement-Dependent Cytolysis by Hepatitis C Virus.","date":"2016","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/27357152","citation_count":18,"is_preprint":false},{"pmid":"7505002","id":"PMC_7505002","title":"A monoclonal antibody against human decay-accelerating factor (DAF, CD55), D17, which lacks reactivity with semen-DAF.","date":"1993","source":"Immunology letters","url":"https://pubmed.ncbi.nlm.nih.gov/7505002","citation_count":18,"is_preprint":false},{"pmid":"34014977","id":"PMC_34014977","title":"Phosphatidylcholine mediates the crosstalk between LET-607 and DAF-16 stress response pathways.","date":"2021","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34014977","citation_count":17,"is_preprint":false},{"pmid":"34874004","id":"PMC_34874004","title":"Characterization of the endogenous DAF-12 ligand and its use as an anthelmintic agent in Strongyloides stercoralis.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/34874004","citation_count":17,"is_preprint":false},{"pmid":"21953001","id":"PMC_21953001","title":"Expression of complement regulatory proteins CD55, CD59, CD35, and CD46 in rheumatoid arthritis.","date":"2011","source":"Revista brasileira de reumatologia","url":"https://pubmed.ncbi.nlm.nih.gov/21953001","citation_count":16,"is_preprint":false},{"pmid":"28624443","id":"PMC_28624443","title":"Inhibitory effect of trans-caryophyllene (TC) on leukocyte-endothelial attachment.","date":"2017","source":"Toxicology and applied pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/28624443","citation_count":16,"is_preprint":false},{"pmid":"20851473","id":"PMC_20851473","title":"Toxic effects of Cr(VI) and Cr(III) on energy metabolism of heterotrophic Euglena gracilis.","date":"2010","source":"Aquatic toxicology (Amsterdam, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/20851473","citation_count":16,"is_preprint":false},{"pmid":"31027358","id":"PMC_31027358","title":"Bee Venom Alleviates Atopic Dermatitis Symptoms through the Upregulation of Decay-Accelerating Factor (DAF/CD55).","date":"2019","source":"Toxins","url":"https://pubmed.ncbi.nlm.nih.gov/31027358","citation_count":16,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":44238,"output_tokens":6349,"usd":0.113975},"stage2":{"model":"claude-opus-4-6","input_tokens":9975,"output_tokens":4208,"usd":0.232612},"total_usd":0.346587,"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\": 1996,\n      \"finding\": \"CD55 (DAF) was identified as the cellular ligand for the seven-span transmembrane receptor CD97; the interaction was mapped to the NH2-terminal short consensus repeat (SCR) of CD55, and erythrocytes lacking CD55 (from PNH or Inab phenotype patients) failed to adhere to CD97 transfectants, establishing specificity.\",\n      \"method\": \"Cell adhesion assay with CD97-transfected COS cells, blocking mAb against CD55 SCR1, and CD55-null erythrocytes as negative controls\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal functional validation with transfectants, blocking antibody, and disease-derived null cells; replicated in multiple follow-up studies\",\n      \"pmids\": [\"9064337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"CD55 (DAF) functions as the receptor mediating attachment and infection by multiple echovirus serotypes; anti-DAF mAbs blocked echovirus 7 attachment, phospholipase C treatment (removing GPI-anchored proteins) abolished binding, and CHO cells expressing human DAF gained the ability to bind echovirus.\",\n      \"method\": \"Anti-DAF mAb blocking assay, phosphatidylinositol-specific phospholipase C treatment, and DAF-transfected CHO cell binding assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (mAb block, enzymatic GPI removal, gain-of-function transfection) in a single study\",\n      \"pmids\": [\"7517044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"CD55 (DAF) is the HeLa cell receptor for Enterovirus 70 (EV70); a blocking mAb (EVR1) directed against CD55 inhibited EV70 binding and infection, and stable expression of human DAF in NIH 3T3 cells conferred susceptibility to EV70 replication.\",\n      \"method\": \"mAb blocking assay, immunoprecipitation identifying ~75 kDa GPI-anchored glycoprotein, and stable DAF-transfected cell infection assay\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function transfection plus mAb blocking plus biochemical identification; multiple orthogonal methods\",\n      \"pmids\": [\"8764022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The CD55-binding site on CD97 requires at least three tandemly linked EGF domains; deletion mutants of CD97 lacking individual EGF domains abolished CD55 binding, and mAbs against EGF domain 1 and removal of Ca2+ (required by EGF2 and EGF5 binding sites) blocked the interaction. Larger CD97 isoforms with additional EGF domains had significantly lower affinity for CD55, indicating that alternative splicing regulates ligand specificity.\",\n      \"method\": \"EGF domain deletion mutants in binding assay, mAb blocking, Ca2+ chelation experiments\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — systematic mutagenesis/deletion of receptor domains with functional binding readout, multiple orthogonal approaches\",\n      \"pmids\": [\"9603477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"CD55 and CD59 co-immunoprecipitate with a common 80-kDa glycoprotein and (glyco)lipids in detergent-resistant complexes, and these complexes contain an associated protein kinase activity, suggesting CD55 is part of a GPI-anchored signaling complex.\",\n      \"method\": \"Co-immunoprecipitation from detergent lysates of HPB-ALL cell line, SDS-PAGE analysis, protein kinase activity assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single co-IP with kinase activity readout; not independently replicated with orthogonal structural methods\",\n      \"pmids\": [\"1715364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"CD55's complement regulatory activity is mediated through its third short consensus repeat (SCR3), and the GPI anchor connects CD55 with associated tyrosine kinases on the inner leaflet, enabling signaling in addition to complement decay acceleration.\",\n      \"method\": \"Structural domain analysis, functional complement assays, and review of biochemical fractionation studies\",\n      \"journal\": \"The Journal of laboratory and clinical medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — domain mapping and functional complement assay, but mechanistic signaling link inferred rather than directly demonstrated\",\n      \"pmids\": [\"7511675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mouse CD55 (both GPI-anchored and transmembrane isoforms) inhibits C3b deposition and protects cells from complement lysis; CD55 knockout mouse erythrocytes failed to adhere to mouse CD97 transfectants, and the CD97–CD55 interaction is species-restrictive (human erythrocytes did not bind mouse CD97).\",\n      \"method\": \"Stable transfection of DAF isoforms in CHO cells, C3b deposition assay, haemolytic assay, adhesion assay with DAF knockout mouse erythrocytes\",\n      \"journal\": \"Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — gain-of-function reconstitution in CHO cells with functional complement assays plus loss-of-function (knockout) adhesion assay\",\n      \"pmids\": [\"10540231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Multiple mouse DAF isoforms generated by alternative splicing (from two genes Daf-GPI and Daf-TM) were identified; both TM and GPI-anchored forms were stably expressed in CHO cells and conferred protection from C3b deposition and complement-mediated lysis, demonstrating functional activity of distinct isoforms.\",\n      \"method\": \"Molecular cloning, Northern blot, stable transfection in CHO cells, C3b deposition assay, cell lysis assay, soluble recombinant DAF haemolytic inhibition assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple functional complement assays in transfected cells\",\n      \"pmids\": [\"10417349\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Cardiovirulent coxsackievirus B3 (CVB3) uses CD55 as an attachment receptor on HeLa cells; anti-DAF mAbs directed against SCR2 and SCR3 most effectively blocked binding and infection, and virus binding was associated with CD55 downregulation at the cell surface. CVB3 did not interact with structurally related complement regulators CD35, CD46, Factor H, or C4BP.\",\n      \"method\": \"Anti-DAF mAb blocking, phospholipase C treatment to remove GPI-anchored proteins, flow cytometry of CD55 surface expression, competitive binding assays\",\n      \"journal\": \"Virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (mAb block, enzymatic removal, flow cytometry) with domain mapping; receptor specificity established by negative controls\",\n      \"pmids\": [\"9601501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"A DAF-using echovirus 11 (EV11) strain enters cells via lipid rafts in a cholesterol- and cytoskeleton-dependent manner. DAF usage by EV11 enables the virus to associate with lipid raft components (Triton X-100 resistant fractions), and this raft-dependent entry pathway is post-binding but prior to RNA uncoating.\",\n      \"method\": \"Pharmacological inhibitors of endocytosis pathways, RNA transfection and virus-binding assays, confocal microscopy, co-purification of virus with lipid raft fractions after Triton X-100 extraction\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (pharmacological, biochemical fractionation, imaging) dissecting the entry mechanism\",\n      \"pmids\": [\"12186914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CD55 expression is induced by hypoxia on the apical membrane of mucosal epithelial cells via a HIF binding site in the CD55 promoter (~200 bp region), and overexpression of CD55 in non-hypoxic epithelia promotes apical clearance of neutrophils; peptide mimetics of the PMN-binding site on CD55 blocked this clearance.\",\n      \"method\": \"Hypoxia gene expression screen, CD55 mRNA/protein induction assay, CD55 transfection in normoxic cells, PMN clearance assay, peptide mimetic blocking, promoter-reporter assay with HIF binding site mutation\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods: transcriptional mapping, gain-of-function, and peptide blocking with defined functional readout\",\n      \"pmids\": [\"15923405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CD55 is part of the LPS receptor complex and contributes to LPS signaling; CD55 transfection in CHO cells conferred NF-κB translocation after LPS/lipid A stimulation, co-immunoprecipitation showed CD55–lipid A interaction, FRET demonstrated CD55–lipid A proximity in human monocytes, and LPS-induced clustering of CD55 with CD11/CD18 was observed. MAP kinase pathways (p38, JNK, ERK) are activated downstream and can be blocked at TLR4.\",\n      \"method\": \"CHO cell transfection with human CD55, NF-κB reporter assay, co-immunoprecipitation with anti-lipid A mAb, FRET analysis in human monocytes, MAP kinase phosphorylation assays, TLR4 inhibition\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (co-IP, FRET, gain-of-function transfection, signaling pathway assays) in a single study\",\n      \"pmids\": [\"12731067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Deletion of CD55 in mouse models of rheumatoid arthritis (collagen-induced and K/BxN serum-transfer models) resulted in decreased arthritis rather than the disease aggravation seen in other inflammatory models, indicating that CD55–CD97 interaction on synoviocytes/macrophages promotes joint inflammation.\",\n      \"method\": \"CD55 knockout and CD97 knockout mice in two arthritis models, clinical scoring, immunohistochemistry\",\n      \"journal\": \"Arthritis and rheumatism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic KO with defined disease phenotype in two independent models; both CD55 and CD97 KO phenocopied each other\",\n      \"pmids\": [\"20131275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CD55 is an essential host factor required for P. falciparum invasion of erythrocytes; CD55-null red blood cells derived from hematopoietic stem cells were refractory to invasion by all P. falciparum isolates tested because parasites failed to properly attach to the erythrocyte surface.\",\n      \"method\": \"Forward genetic screen using cultured RBCs from hematopoietic stem cells, CD55-null erythrocytes in parasite invasion assay\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function in relevant primary human cell type with clear mechanistic readout (failure of parasite attachment); forward genetic screen design\",\n      \"pmids\": [\"25954012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Biallelic loss-of-function mutations in CD55 cause loss of CD55 expression, leading to increased complement activation with surface deposition of complement and generation of soluble C5a on T lymphocytes, defective costimulatory function, and defective cytokine modulation. Genetic reconstitution of CD55 or treatment with a complement-inhibitory antibody reversed abnormal complement activation.\",\n      \"method\": \"Whole-exome sequencing, flow cytometry of complement deposition, complement activation assays on patient T lymphocytes, exogenous CD55 expression rescue, complement-inhibitory antibody rescue\",\n      \"journal\": \"The New England journal of medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human disease genetics combined with functional cellular assays and genetic/pharmacologic rescue; multiple orthogonal methods\",\n      \"pmids\": [\"28657829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CD55 regulates cancer stem cell self-renewal and cisplatin resistance in a complement-independent manner via lipid raft localization; CD55 activates ROR2/JNK signaling to control self-renewal and core pluripotency genes, and in parallel activates LCK (lymphocyte-specific protein tyrosine kinase) signaling to induce DNA repair genes and cisplatin resistance.\",\n      \"method\": \"Comparative CSC/non-CSC transcriptomic analysis, lipid raft fractionation, ROR2/JNK pathway inhibition, LCK inhibition with saracatinib, KD/KO with self-renewal and chemoresistance phenotype readouts\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — complement-independent signaling mechanism established by lipid raft fractionation, pathway-specific inhibitors, and defined downstream gene targets with functional phenotypes\",\n      \"pmids\": [\"28838952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"HCV infection upregulates CD55 expression on hepatocytes via HCV core protein-mediated enhancement of CD55 promoter activity dependent on CREB and SP-1 binding sites; IL-6 further augments this induction. CD55 associates with HCV particles purified by sucrose density gradient, and CD55-blocking antibodies with complement inhibited HCV infection.\",\n      \"method\": \"CD55 mRNA/protein assay in HCV-infected hepatocytes, luciferase-based promoter activity assay with CREB/SP-1 site mutation, sucrose density gradient ultracentrifugation of HCV particles, polyclonal anti-CD55 capture of HCV, blocking antibody infection assay\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — promoter mutagenesis, biochemical co-purification of CD55 with virus, and functional infection blocking; multiple orthogonal methods\",\n      \"pmids\": [\"23658447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HCV infection induces synthesis of a secreted CD55 isoform (sCD55) via alternative splicing; conditioned medium from HCV-infected cells inhibits C3 convertase activity and complement-dependent cytolysis in a CD55-dependent manner, implicating sCD55 in complement evasion in the infected microenvironment.\",\n      \"method\": \"RT-PCR for sCD55 isoform, C3 convertase activity assay with conditioned medium, complement-dependent cytolysis assay, CD55-blocking antibody reversal\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional assays demonstrating sCD55-mediated complement inhibition, but mechanistic details of splicing regulation not fully defined\",\n      \"pmids\": [\"27357152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ST3GAL1-mediated O-linked sialylation of CD55 protects cancer cells from complement-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity; ST3GAL1 silencing shifted CD55 O-glycan profile from disialylated core 2 to nonsialylated/monosialylated forms, increasing C3 deposition on breast cancer cells.\",\n      \"method\": \"ST3GAL1 siRNA knockdown, tandem mass spectrometry of N- and O-linked oligosaccharides released from CD55, C3 deposition assay, complement-mediated lysis assay, ADCC assay\",\n      \"journal\": \"Cancer immunology research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct structural glycan analysis combined with functional complement assays; multiple orthogonal methods in a single study\",\n      \"pmids\": [\"33177111\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Activation of dsRNA sensors TLR3, MDA5, and RIG-I in fibroblast-like synoviocytes upregulates CD55 expression, which enhances the capacity of fibroblasts to bind CD97-loaded beads; this upregulation was blocked by anti-CD55 antibodies, linking innate immune dsRNA sensing to the CD55–CD97 adhesion axis.\",\n      \"method\": \"Cytokine/TLR ligand stimulation of FLS, flow cytometry of CD55 expression, CD97-loaded bead binding assay, anti-CD55 antibody blocking\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — functional bead binding assay with antibody blocking establishes upregulation-to-function link, but mechanism of transcriptional induction not fully delineated\",\n      \"pmids\": [\"22590509\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Neurosteroids progesterone and allopregnanolone enhance CD55 production following brain contusion injury in rats, suggesting that steroid-mediated induction of CD55 is a mechanism by which these steroids reduce complement convertase activity and neuroinflammation.\",\n      \"method\": \"Rat cortical contusion model, CD55 protein quantification after progesterone/allopregnanolone treatment\",\n      \"journal\": \"Neuroscience letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single in vivo measurement; correlation between treatment and CD55 induction without direct mechanistic dissection\",\n      \"pmids\": [\"17826908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Recombinant human CD55 (DAF) protects primary cultured neuronal cells from chemical hypoxia by inhibiting complement activation (reducing C3a accumulation and MAC formation) and by decreasing activated Src kinase (pTyr416-Src), caspase-9, and caspase-3 activity, reducing neuronal apoptosis and dendritic spine loss.\",\n      \"method\": \"Primary cortical neuron culture, NaCN hypoxia model, recombinant DAF treatment, TUNEL assay, MTT assay, dendritic spine counting, immunofluorescence for complement components and MAC, Western blot for activated caspases and Src\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — exogenous recombinant protein treatment with multiple functional and biochemical readouts; mechanism partially established\",\n      \"pmids\": [\"20380727\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"CD55 is overexpressed on tumor cells and is upregulated on endothelial cells by VEGF at the cell surface and in the extracellular matrix (ECM); MMP-7 releases intact, functionally active CD55 from ECM (unlike papain which degrades it or collagenase which fails to release it), suggesting a role for soluble CD55 in protecting tumor microenvironment from complement.\",\n      \"method\": \"VEGF treatment of HUVEC cells, immunoassay of cell surface and ECM CD55, metalloproteinase treatment assays, functional complement assay of released CD55\",\n      \"journal\": \"Tissue antigens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — functional release and complement-inhibitory activity assay of ECM-derived CD55; MMP-7 specificity established by comparison with other proteases\",\n      \"pmids\": [\"12445304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"EGFR/Wnt/β-catenin signaling induces lncRNA LINC00973 expression, which sponges CD55-targeting miR-216b, resulting in upregulated CD55 expression that suppresses complement activation and CD8+ T cell activation in lung cancer; anti-CD55/CD59 antibody treatment or LINC00973 promoter mutation activated complement and CD8+ T cells, and combined anti-CD55/CD59 with anti-PD-1 showed synergistic tumor inhibition.\",\n      \"method\": \"β-catenin ChIP for LINC00973 promoter, miRNA sponging assay, LINC00973 promoter mutation, anti-CD55/CD59 neutralizing antibody, complement activation assay, CD8+ T cell activation assay, tumor growth assay\",\n      \"journal\": \"Nature cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — comprehensive pathway dissection from upstream signaling to CD55 regulation to functional complement/immune evasion outcome; multiple orthogonal methods\",\n      \"pmids\": [\"36271172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Parainfluenza virus 5 (PIV5) incorporates functional CD55 into virions, and virion-incorporated CD55 (but not CD46) confers high resistance to complement-mediated neutralization; PIV5 infection upregulates cell surface CD55 (further enhanced by TNF-α), and virus derived from cells with higher CD55 levels is more resistant to complement neutralization.\",\n      \"method\": \"Complement neutralization assay with virus containing CD55 alone, CD46 alone, or both, flow cytometry of CD55 surface levels, virus derived from cells with modulated CD55 levels\",\n      \"journal\": \"Virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — comparative functional assay with defined viral particles; mechanism of complement evasion directly attributed to virion-incorporated CD55\",\n      \"pmids\": [\"27505156\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CD55 (DAF) is a GPI-anchored complement regulatory protein that accelerates the decay of C3/C5 convertases via its SCR domains (particularly SCR3), and additionally functions as a cellular ligand for the adhesion receptor CD97 (via CD55's SCR1 and Ca2+-dependent EGF domains on CD97), as a receptor for multiple enteroviruses (echoviruses, EV70, CVB3) through its SCR2-3 domains, as an essential erythrocyte surface factor required for P. falciparum attachment, as a component of the LPS receptor complex linked to NF-κB and MAP kinase signaling, and—in a complement-independent context—as a lipid raft-localized signaling node that activates ROR2/JNK and LCK pathways to drive cancer stem cell self-renewal and chemoresistance; its activity is further modulated by ST3GAL1-mediated O-sialylation, HIF-dependent transcriptional induction at sites of inflammation, and virus-induced upregulation for immune evasion.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CD55 (decay-accelerating factor, DAF) is a GPI-anchored complement regulatory glycoprotein that accelerates the decay of C3/C5 convertases through its short consensus repeat (SCR) domains—particularly SCR3—thereby protecting host cells from autologous complement attack; biallelic loss-of-function mutations cause uncontrolled complement deposition on lymphocytes, leading to the CHAPLE syndrome of protein-losing enteropathy [PMID:28657829, PMID:7511675]. Beyond complement regulation, CD55 serves as a multifunctional surface receptor: it is the cellular attachment factor for echoviruses, enterovirus 70, and coxsackievirus B3 (engaging SCR2–SCR3) [PMID:7517044, PMID:8764022, PMID:9601501], a ligand for the adhesion receptor CD97 (via SCR1) whose interaction promotes leukocyte adhesion and joint inflammation [PMID:9064337, PMID:20131275], and an essential erythrocyte surface determinant required for P. falciparum invasion [PMID:25954012]. In a complement-independent context, lipid raft–localized CD55 activates ROR2/JNK and LCK signaling pathways to drive cancer stem cell self-renewal and chemoresistance, while its surface abundance is regulated transcriptionally by HIF under hypoxia, by EGFR/Wnt/β-catenin–LINC00973–miR-216b axis in tumors, and post-translationally by ST3GAL1-mediated O-sialylation that enhances complement-protective activity [PMID:28838952, PMID:15923405, PMID:36271172, PMID:33177111].\",\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Whether GPI-anchored complement regulators participate in signaling complexes was unknown; co-immunoprecipitation of CD55 and CD59 with an 80-kDa glycoprotein bearing kinase activity established that CD55 resides in detergent-resistant complexes with signaling potential.\",\n      \"evidence\": \"Co-immunoprecipitation from HPB-ALL cell lysates with kinase activity assay\",\n      \"pmids\": [\"1715364\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single co-IP without reciprocal validation or identification of the 80-kDa partner\", \"No downstream signaling pathway delineated\", \"Functional consequence of kinase activity not tested\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"The question of whether CD55 has functions beyond complement regulation was answered when it was identified as the cellular receptor for multiple echovirus serotypes, with GPI-anchored presentation essential for virus binding.\",\n      \"evidence\": \"Anti-DAF mAb blocking, PI-PLC treatment, and gain-of-function DAF-transfected CHO cell binding assay\",\n      \"pmids\": [\"7517044\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Viral entry mechanism downstream of CD55 binding not resolved\", \"Whether CD55 serves as entry receptor versus attachment receptor not distinguished\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Mapping of complement-regulatory activity to SCR3 established the structural basis for decay-accelerating function and separated it from the GPI anchor's potential signaling role.\",\n      \"evidence\": \"Domain analysis and functional complement assays\",\n      \"pmids\": [\"7511675\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic signaling link through the GPI anchor inferred but not directly demonstrated\", \"Structural basis of SCR3 interaction with convertases not resolved at atomic level\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"CD55 was identified as the ligand for the seven-span transmembrane receptor CD97, mapping the interaction to SCR1 and establishing a cell adhesion function distinct from complement regulation and virus binding.\",\n      \"evidence\": \"Cell adhesion assay with CD97-transfected COS cells, anti-SCR1 blocking mAb, and CD55-null erythrocytes from PNH/Inab patients\",\n      \"pmids\": [\"9064337\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream signaling through CD97 upon CD55 engagement not characterized\", \"In vivo physiological consequence of the interaction not tested at this point\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Extension of CD55's virus receptor role to enterovirus 70 demonstrated that diverse picornaviruses convergently exploit CD55 for cell entry.\",\n      \"evidence\": \"mAb blocking and gain-of-function DAF-transfected NIH 3T3 cells conferring EV70 susceptibility\",\n      \"pmids\": [\"8764022\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular determinants on CD55 engaged by EV70 not mapped at domain level\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"CVB3 was shown to use CD55 SCR2–SCR3 for attachment, and the CD97 EGF domain requirements for CD55 binding were mapped, together defining two distinct interaction surfaces on CD55.\",\n      \"evidence\": \"Anti-DAF domain-specific mAb blocking for CVB3; EGF domain deletion mutants and Ca²⁺ chelation for CD97 binding\",\n      \"pmids\": [\"9601501\", \"9603477\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CVB3 requires a coreceptor for entry not resolved\", \"Structural basis of CD55 SCR engagement by virus versus CD97 not compared\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Cloning of mouse DAF isoforms (GPI-anchored and transmembrane) and demonstration that both protect cells from complement confirmed conservation and showed the CD97–CD55 interaction is species-restrictive.\",\n      \"evidence\": \"Stable transfection of GPI and TM isoforms in CHO cells with C3b deposition and hemolytic assays; DAF KO mouse erythrocyte adhesion assay\",\n      \"pmids\": [\"10540231\", \"10417349\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological role of the TM isoform versus GPI isoform not distinguished in vivo\", \"Species restriction mechanism not structurally explained\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Two studies established CD55's role in the tumor microenvironment: DAF-using echovirus entry occurs through lipid rafts in a cholesterol-dependent manner, and VEGF-induced CD55 in the extracellular matrix is released by MMP-7 as a functional soluble complement inhibitor.\",\n      \"evidence\": \"Lipid raft fractionation and pharmacological inhibition for EV11 entry; VEGF treatment of HUVECs and MMP-7 release assay with complement functional readout\",\n      \"pmids\": [\"12186914\", \"12445304\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether raft localization of CD55 is required for all enterovirus serotypes not tested\", \"In vivo relevance of MMP-7-released soluble CD55 not demonstrated\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"CD55 was shown to be a component of the LPS receptor complex, with direct lipid A binding triggering NF-κB translocation and MAP kinase activation, expanding CD55's role to innate immune signaling.\",\n      \"evidence\": \"CHO cell transfection with NF-κB reporter, co-IP of CD55–lipid A, FRET in human monocytes, MAP kinase phosphorylation assays\",\n      \"pmids\": [\"12731067\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD55 signals independently of TLR4 or functions only as a co-receptor not resolved\", \"Stoichiometry of CD55 in the LPS receptor complex unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Hypoxia-induced CD55 expression via a HIF-responsive promoter element was shown to promote apical neutrophil clearance from mucosal epithelia, linking tissue oxygen sensing to complement regulation at inflamed surfaces.\",\n      \"evidence\": \"Hypoxia gene expression screen, promoter-reporter with HIF site mutation, CD55 overexpression and PMN clearance assay with peptide mimetic blocking\",\n      \"pmids\": [\"15923405\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the PMN surface receptor engaging CD55 during clearance not defined\", \"Whether HIF1α or HIF2α drives CD55 induction not distinguished\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Genetic deletion of CD55 in two independent arthritis models unexpectedly attenuated rather than exacerbated disease, establishing that the CD55–CD97 adhesion axis promotes joint inflammation in vivo.\",\n      \"evidence\": \"CD55 KO and CD97 KO mice in collagen-induced and K/BxN serum-transfer arthritis, clinical scoring, immunohistochemistry\",\n      \"pmids\": [\"20131275\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream signaling through CD97 in synoviocytes/macrophages not characterized\", \"Whether complement-regulatory loss in KO mice partially counteracts the anti-inflammatory effect not assessed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"HCV was found to upregulate CD55 transcription via core protein–driven CREB/SP-1 promoter activation and to physically incorporate CD55 into virion particles, establishing virus-directed exploitation of CD55 for complement evasion.\",\n      \"evidence\": \"Promoter-reporter mutagenesis, sucrose gradient co-purification of CD55 with HCV, anti-CD55 blocking infection assay\",\n      \"pmids\": [\"23658447\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CD55 incorporation into HCV particles is passive or actively selected not determined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"A forward genetic screen identified CD55 as an essential host factor for P. falciparum erythrocyte invasion, demonstrating that CD55-null red blood cells are refractory to parasite attachment.\",\n      \"evidence\": \"Forward genetic screen using cultured CD55-null erythrocytes derived from hematopoietic stem cells, parasite invasion assay\",\n      \"pmids\": [\"25954012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Parasite ligand that engages CD55 not identified\", \"Whether CD55's role is direct binding or membrane organization not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Two discoveries revealed virus-directed CD55 exploitation: PIV5 incorporates functional CD55 into virions conferring complement resistance, and HCV infection induces a secreted CD55 splice isoform (sCD55) that inhibits C3 convertase in the extracellular milieu.\",\n      \"evidence\": \"Complement neutralization assay with PIV5 virions; RT-PCR for sCD55 isoform and C3 convertase/cytolysis assays with conditioned medium\",\n      \"pmids\": [\"27505156\", \"27357152\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Splicing regulatory mechanism for sCD55 generation not defined\", \"Whether sCD55 and virion-incorporated CD55 differ functionally not compared\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Biallelic CD55 loss-of-function mutations were shown to cause CHAPLE syndrome with uncontrolled complement activation on T cells, and separately, complement-independent lipid raft–localized CD55 was found to activate ROR2/JNK and LCK pathways driving cancer stem cell self-renewal and chemoresistance.\",\n      \"evidence\": \"Whole-exome sequencing with functional rescue for CHAPLE; transcriptomic comparison of CSC/non-CSC with lipid raft fractionation, ROR2/JNK and LCK inhibition for cancer signaling\",\n      \"pmids\": [\"28657829\", \"28838952\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CD55 activates ROR2 in the absence of complement ligands not mechanistically resolved\", \"Whether CHAPLE disease severity correlates with residual CD55 activity not studied across genotypes\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"ST3GAL1-mediated O-sialylation was shown to modulate CD55's complement-protective function, with disialylated core 2 O-glycans required for full inhibition of C3 deposition on cancer cells.\",\n      \"evidence\": \"ST3GAL1 siRNA knockdown, tandem mass spectrometry of CD55 glycans, C3 deposition and complement lysis assays in breast cancer cells\",\n      \"pmids\": [\"33177111\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific O-glycosylation sites on CD55 are critical not mapped\", \"Whether sialylation affects CD55's non-complement functions (CD97 binding, virus receptor) not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"An EGFR/Wnt/β-catenin–LINC00973–miR-216b regulatory axis was shown to upregulate CD55 in lung cancer, suppressing both complement activation and CD8⁺ T cell responses; combined anti-CD55/CD59 with anti-PD-1 produced synergistic tumor inhibition.\",\n      \"evidence\": \"β-catenin ChIP, miRNA sponging assay, LINC00973 promoter mutation, anti-CD55/CD59 antibody with complement and T cell activation assays, in vivo tumor growth\",\n      \"pmids\": [\"36271172\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether this regulatory axis operates in cancer types beyond lung cancer not tested\", \"Direct contribution of CD55 versus CD59 to immune evasion not individually quantified in the combination treatment\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The parasite ligand engaging CD55 during P. falciparum invasion remains unidentified, the structural basis of CD55's complement-independent signaling through ROR2 is unresolved, and whether post-translational modifications (sialylation, GPI remodeling) differentially regulate CD55's distinct functions (complement regulation, CD97 binding, virus entry, parasite attachment) has not been systematically addressed.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"P. falciparum ligand for CD55 unknown\", \"Atomic-resolution structure of CD55 in complex with C3 convertase not available\", \"Systematic comparison of glycan requirements across CD55's multiple functions not performed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 6, 7, 14, 17, 18]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 3, 12]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [1, 2, 8]},\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 2, 6, 8, 10, 13, 14, 15, 24]},\n      {\"term_id\": \"GO:0031012\", \"supporting_discovery_ids\": [22]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [17, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": []},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 6, 7, 14, 18, 23]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [11, 15, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [14, 23]}\n    ],\n    \"complexes\": [\n      \"LPS receptor complex\"\n    ],\n    \"partners\": [\n      \"CD97\",\n      \"CD59\",\n      \"ROR2\",\n      \"LCK\",\n      \"ST3GAL1\",\n      \"TLR4\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}