{"gene":"KLRK1","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2002,"finding":"Binding of soluble MIC (shed from tumors) to NKG2D induces endocytosis and degradation of NKG2D on T cells, causing systemic downregulation of NKG2D expression on tumor-infiltrating and peripheral blood T cells and impairing effector T cell responsiveness.","method":"Flow cytometry of patient samples, in vitro endocytosis/degradation assays, correlation of circulating soluble MICA with NKG2D levels","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional assays, patient samples correlated with in vitro mechanism, replicated concept across multiple labs","pmids":["12384702"],"is_preprint":false},{"year":2001,"finding":"Ectopic expression of murine NKG2D ligands Rae1β or H60 on tumor cell lines causes potent rejection by syngeneic mice mediated by NK cells and/or CD8+ T cells, directly linking NKG2D ligand expression to tumor rejection and priming of cytotoxic T cells and NK cell sensitization in vivo.","method":"In vivo syngeneic tumor rejection assays, adoptive transfer, NK cell depletion experiments","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic/cellular epistasis with depletion experiments, replicated across multiple tumor lines","pmids":["11557981"],"is_preprint":false},{"year":2005,"finding":"NKG2D (human) transmits signals via its association with the DAP10 adapter subunit, coupling to phosphoinositide 3-kinase (PI3K); in mice, alternatively spliced isoforms signal through either DAP10 or DAP12.","method":"Biochemical co-immunoprecipitation, signaling assays, splice-isoform analysis","journal":"Cancer immunology research","confidence":"High","confidence_rationale":"Tier 2 / Strong — DAP10/DAP12 association replicated across multiple studies and labs","pmids":["26041808"],"is_preprint":false},{"year":2011,"finding":"Cancer cells themselves express NKG2D in complex with DAP10; triggering NKG2D on these cancer cells activates the PI3K–AKT–mTOR oncogenic signaling axis and downstream effectors S6K1 and 4E-BP1, as well as JNK and ERK MAP kinase cascades, increasing bioenergetic metabolism and proliferation of tumor cells.","method":"Immunoprecipitation, phosphorylation assays, siRNA knockdown, overexpression in tumor lines, bioenergetics measurements","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, multiple signaling readouts, functional rescue, single lab with multiple orthogonal methods","pmids":["21321202"],"is_preprint":false},{"year":2021,"finding":"NKG2D discriminates between its ligands through selective mechanical force-induced conformational changes: force application selectively prolongs NKG2D interaction lifetimes with MICA and MICB (but not ULBPs), with MICA undergoing force-induced rotational conformational changes that form additional hydrogen bonds at the NKG2D interface, impeding dissociation under force and determining downstream NK cell activation.","method":"Live-cell single-molecule biomechanical assay, steered molecular dynamics simulations, mutagenesis, in situ binding kinetics","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — single-molecule force assay combined with molecular dynamics simulation and mutagenesis in one rigorous study","pmids":["34913508"],"is_preprint":false},{"year":2004,"finding":"NKG2D-mediated cytotoxicity and cytokine secretion are regulated by inhibitory Ly49 receptors (Ly49A/G and Ly49C/I) in a manner dependent on both H60 expression level and MHC class I identity on target cells; even high H60 expression cannot overcome Ly49A/G inhibition, establishing epistatic crosstalk between activating NKG2D and inhibitory receptors.","method":"NK cell cytotoxicity assays with antibody crosslinking, IFN-γ/GM-CSF secretion assays, titration of H60 expression on target cells","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays with defined receptor manipulations, single lab, multiple ligand levels tested","pmids":["15328154"],"is_preprint":false},{"year":2010,"finding":"Resveratrol enhances NK cell cytotoxicity through NKG2D-dependent JNK and ERK-1/2 MAP kinase pathways, leading to increased perforin expression; siRNA knockdown of JNK-1 or ERK-2 abolishes the resveratrol-enhanced cytotoxicity.","method":"NK92 cell culture, siRNA knockdown of JNK-1/ERK-2, kinase inhibitor treatments, cytotoxicity assays, perforin western blot","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown plus pharmacological inhibitors with multiple readouts, single lab","pmids":["20082299"],"is_preprint":false},{"year":2011,"finding":"Simultaneous stimulation of CD8+ T cells through CD3 and NKG2D (or a chimeric NKG2D-CD3ζ receptor) activates β-catenin signaling and suppresses production of anti-inflammatory cytokines (IL-10, IL-9, IL-13, VEGF-α) in a β-catenin- and PPARγ-dependent manner, distinct from TCR+CD28 costimulation.","method":"Chimeric receptor expression, β-catenin reporter assays, cytokine ELISA, siRNA, pharmacological inhibition","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — chimeric receptor approach combined with siRNA and inhibitors, single lab","pmids":["21518928"],"is_preprint":false},{"year":2006,"finding":"Human NKG2D is coupled by the DAP10 adapter to phosphoinositide 3-kinase (PI3K) and specifically interacts with stress-inducible ligands (MICA, MICB, ULBP); on CD4+ T cells specific for human cytomegalovirus, NKG2D engagement synergizes with TCR-dependent activation, triggering proliferation and cytokine production (IFN-γ, TNF-α), functioning as a costimulatory receptor.","method":"Flow cytometry, CFSE proliferation assay, intracellular cytokine staining, mAb crosslinking of NKG2D","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays with antibody crosslinking, single lab, multiple readouts","pmids":["17109473"],"is_preprint":false},{"year":2013,"finding":"NKG2D ligand expression on senescent cells (MICA and ULBP2) is necessary for efficient NK-mediated cytotoxicity toward senescent fibroblasts; initial NKG2D ligand expression in senescence depends on the DNA damage response, while continuous expression is regulated by the ERK signaling pathway. In mice lacking NKG2D, senescent liver stellate cells accumulate and liver fibrosis is increased.","method":"In vitro senescence models, NK cytotoxicity assays, NKG2D-knockout mice, liver fibrosis histology, ERK/DDR pathway inhibitors","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — NKG2D knockout in vivo combined with in vitro mechanistic dissection, single lab","pmids":["26878797"],"is_preprint":false},{"year":2019,"finding":"PARP1 represses expression of NKG2D ligands on leukemic stem cells (LSCs); genetic or pharmacological inhibition of PARP1 induces NKG2DL on the LSC surface (but not on healthy or pre-leukemic cells), rendering LSCs susceptible to NK cell killing and suppressing leukemogenesis in patient-derived xenotransplant models.","method":"PARP1 genetic deletion, PARP1 inhibitor treatment, patient-derived xenotransplant models, NK cell cytotoxicity assays, flow cytometry","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic and pharmacological perturbation of identified writer (PARP1), validated in patient-derived in vivo model with multiple orthogonal approaches","pmids":["31316209"],"is_preprint":false},{"year":2013,"finding":"NK cell NKG2D and granzyme B are both required for HDM-induced allergic pulmonary inflammation; NKG2D-deficient mice are resistant to allergic inflammation, and adoptive transfer of wild-type NK cells (but not CD3+ T cells) restores the response only if the NK cells express granzyme B.","method":"NKG2D-knockout mouse model, adoptive transfer of NK cells, HDM-induced allergy model, lung histology, IgE measurement","journal":"The Journal of allergy and clinical immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — NKG2D KO combined with adoptive transfer epistasis, multiple phenotypic readouts, granzyme B requirement defined","pmids":["24290277"],"is_preprint":false},{"year":2021,"finding":"NKG2D ligands are induced on lung endothelial and epithelial cells following ischemia-reperfusion injury; NK cell NKG2D receptor ligation mediates acute lung injury, as antibody-mediated NKG2D blockade or NK cell depletion abrogates injury in mouse models.","method":"NK cell-deficient mouse strain, adoptive transfer, antibody blockade, IRI mouse models, NK cell trafficking/maturation analysis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — NK cell-deficient strain rescue, adoptive transfer, and antibody blockade all converge, multiple models","pmids":["33290276"],"is_preprint":false},{"year":2016,"finding":"CBP/p300 acetyltransferases regulate basal and stress-induced expression of NKG2D ligands (MICA/B, ULBP2, RAE-1) on tumor cells; loss of CBP/p300 reduces surface NKG2D ligand expression and NK cell-mediated killing; CREB binding and histone acetylation at NKG2D ligand promoters are increased during upregulation.","method":"siRNA knockdown of CBP/p300, ChIP assay, HDAC inhibitor treatment, NK cytotoxicity assays, Eμ-Myc mouse lymphoma model","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and functional rescue, in vitro and in vivo validation, single lab","pmids":["27477692"],"is_preprint":false},{"year":2013,"finding":"Spironolactone upregulates NKG2D ligand expression on colon cancer cells through the ATM-Chk2-mediated DNA damage checkpoint pathway via RXRγ activation (not the mineralocorticoid receptor), enhancing NK cell-mediated tumor elimination.","method":"siRNA library screen of nuclear hormone receptors, ATM-Chk2 pathway inhibitors, NKG2DL expression assays, NK cytotoxicity assays","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA screen identified RXRγ as the mediator, confirmed with pathway inhibitors and functional NK killing assay, single lab","pmids":["24190430"],"is_preprint":false},{"year":2021,"finding":"β-catenin signaling (via CTNNB1 mutation) downregulates expression of ULBP1 and ULBP2 NKG2D ligands in hepatocellular carcinoma; in mouse HCC models, β-catenin signaling reduces Rae-1 expression through TCF4 binding at ligand promoters.","method":"RNA-seq, TaqMan expression profiling, ChIP (TCF4 binding), mouse HCC models with β-catenin activation","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP identifying transcription factor binding combined with mouse in vivo model, single lab","pmids":["33484773"],"is_preprint":false},{"year":2005,"finding":"H60 and MICA can suppress T cell proliferation through a receptor other than NKG2D in an IL-10-dependent manner, demonstrating that NKG2D ligands can mediate inhibitory effects on T cells independent of the NKG2D receptor itself.","method":"T cell proliferation assays with IL-10 neutralization, NKG2D-blocking antibodies, loss-of-function experiments","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — NKG2D-blocking antibody controls with IL-10 neutralization, single lab, two orthogonal methods","pmids":["16091471"],"is_preprint":false},{"year":2004,"finding":"NKG2D is a homodimeric C-type lectin-like receptor that interacts with asymmetric monomeric ligands in 2:1 complexes; each NKG2D monomer uses an equivalent surface to bind structurally divergent ligand surfaces through 'rigid adaptation' rather than induced-fit, explaining recognition degeneracy.","method":"Crystal structure analysis, thermodynamic and kinetic analyses of multiple NKG2D-ligand pairs","journal":"Advances in protein chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple crystal structures combined with thermodynamic and kinetic analyses across multiple ligand pairs","pmids":["15500864"],"is_preprint":false},{"year":2018,"finding":"IDO1 promotes expression of miR-18a, which directly downregulates NKG2D (via its 3'UTR) and the NKG2D ligand Mult-1 (via its 3'UTR); IDO1 promotes binding of miR-18a to AGO2, leading to degradation of Mult-1 mRNA and inhibition of NKG2D translation, thereby impairing NK cell cytotoxicity.","method":"Co-immunoprecipitation of AGO2, 3'UTR luciferase reporter assays, miR-18a overexpression/inhibition, INCB024360 treatment, IDO1 overexpression","journal":"Molecular immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — AGO2 Co-IP, 3'UTR binding assays, pharmacological rescue, single lab","pmids":["30268986"],"is_preprint":false},{"year":2017,"finding":"NKG2D-dependent antitumor effects of temozolomide (TMZ) and irradiation (IR) in glioblastoma require an intact DNA damage response and are attenuated by MGMT; blocking NKG2D pathway or using NKG2D-knockout mice reduces the survival benefit of TMZ or IR in syngeneic orthotopic glioblastoma models.","method":"NKG2D-knockout mouse model, NKG2D-blocking antibodies, syngeneic orthotopic glioblastoma model, in vitro DDR pathway analysis","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — NKG2D KO plus antibody blockade in vivo, multiple glioblastoma models, single lab","pmids":["29162646"],"is_preprint":false},{"year":2013,"finding":"NKG2D signaling in human CD8+ T cells co-stimulates TCR activation; on NK cells, NKG2D can act as a primary activation receptor sufficient to trigger cytotoxicity.","method":"Antibody crosslinking, cytotoxicity assays, cytokine secretion assays comparing NK vs. T cell responses","journal":"Current opinion in immunology","confidence":"Medium","confidence_rationale":"Tier 3 / Strong — replicated across multiple labs using antibody crosslinking and functional assays","pmids":["11973127"],"is_preprint":false},{"year":2013,"finding":"NKG2D in T cells (NKG2D cross-linkage) augments anti-CD3-triggered proliferation and IFN-γ/TNF-α production in CD8 T cells; in GCA and PMR patients, NKG2D is preferentially expressed on senescent CD4+CD28- and CD8+ T cells and NKG2D ligands are present in temporal arteries, supporting a costimulatory role in autoimmune vasculitis.","method":"Flow cytometry, CFSE proliferation assay, intracellular cytokine staining, immunofluorescence and immunohistology of temporal artery biopsies","journal":"Annals of the rheumatic diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ex vivo functional assays with tissue validation, single lab","pmids":["23417963"],"is_preprint":false}],"current_model":"KLRK1/NKG2D is a homodimeric C-type lectin-like activating receptor expressed on NK cells, CD8+ T cells, and subsets of other T cells that signals through DAP10 (and DAP12 in mice) to activate PI3K–AKT–mTOR and MAP kinase (JNK, ERK) pathways upon binding a diverse repertoire of stress-induced MHC class I-like ligands (MICA, MICB, ULBPs in humans; Rae-1, H60, Mult1 in mice); it discriminates ligands through selective force-dependent conformational changes (MICA/MICB more than ULBPs), functions as a primary activation receptor on NK cells and a costimulatory receptor on T cells, is downregulated by ligand-induced endocytosis and degradation, and its ligands are regulated transcriptionally (e.g., by CBP/p300, β-catenin/TCF4), post-translationally (proteolytic shedding, exosome release), and by upstream pathways including DNA damage response, PARP1, and IDO1/miR-18a, with soluble shed ligands acting as immune decoys that blunt NKG2D-mediated immunosurveillance."},"narrative":{"mechanistic_narrative":"KLRK1/NKG2D is a homodimeric C-type lectin-like activating receptor of NK cells and CD8+ T cells that couples recognition of stress-induced MHC class I-like ligands to cytotoxicity, cytokine production, and tumor immunosurveillance [PMID:11557981, PMID:15500864, PMID:11973127]. Structurally, it binds asymmetric monomeric ligands (MICA, MICB, ULBPs in humans; Rae-1, H60, Mult1 in mice) in 2:1 complexes, each monomer using an equivalent surface to engage divergent ligands by 'rigid adaptation' rather than induced fit, which explains its recognition degeneracy [PMID:15500864]; ligand discrimination is further refined by mechanical force, which selectively prolongs interaction lifetimes with MICA/MICB through force-induced rotational conformational changes that strengthen the interface, while ULBP binding is force-insensitive [PMID:34913508]. Signaling proceeds through the DAP10 adapter (DAP10 or DAP12 in mouse splice isoforms), coupling to PI3K-AKT-mTOR and to JNK/ERK MAP kinase cascades to drive perforin-dependent cytotoxicity [PMID:26041808, PMID:20082299, PMID:17109473]. Functionally NKG2D operates as a primary activation receptor on NK cells and as a costimulatory receptor on T cells, augmenting TCR/CD3 signaling and proliferation and engaging β-catenin/PPARγ programs distinct from CD28 costimulation [PMID:21518928, PMID:17109473, PMID:11973127]. Its activity is tuned by epistatic crosstalk with inhibitory Ly49 receptors, by ligand-induced endocytosis and degradation of the receptor triggered by soluble shed MIC, and by IDO1-driven miR-18a that directly represses NKG2D and its ligand Mult-1 [PMID:12384702, PMID:15328154, PMID:30268986]. NKG2D ligand abundance is itself a tightly regulated checkpoint: ligands are induced through the DNA damage response and ERK signaling and by CBP/p300 acetyltransferases, and repressed by PARP1 and by β-catenin/TCF4, defining the tumor and senescent-cell contexts in which NKG2D enables killing [PMID:26878797, PMID:31316209, PMID:27477692, PMID:33484773]. Beyond surveillance of tumors and senescent cells, NKG2D engagement drives pathology in allergic pulmonary inflammation and ischemia-reperfusion lung injury and underlies costimulation in autoimmune vasculitis [PMID:24290277, PMID:33290276, PMID:23417963].","teleology":[{"year":2001,"claim":"Established that NKG2D ligand expression on a target cell is sufficient to trigger immune rejection in vivo, linking the receptor directly to tumor elimination.","evidence":"Ectopic Rae1β/H60 expression on syngeneic tumor lines with NK depletion and adoptive transfer in mice","pmids":["11557981"],"confidence":"High","gaps":["Did not resolve the receptor's signaling subunit","Relative NK vs CD8+ T cell contribution not fully partitioned"]},{"year":2002,"claim":"Revealed a tumor immune-evasion mechanism: soluble shed ligand engages NKG2D to drive its endocytosis and degradation, downregulating receptor surface levels and impairing effector responsiveness.","evidence":"Flow cytometry of patient samples correlated with in vitro endocytosis/degradation assays","pmids":["12384702"],"confidence":"High","gaps":["Endocytic trafficking machinery not defined","Whether shedding kinetics differ across ligands not addressed"]},{"year":2004,"claim":"Explained how a single receptor recognizes structurally divergent ligands by showing 2:1 homodimeric binding via rigid adaptation rather than induced fit.","evidence":"Crystal structures with thermodynamic and kinetic analyses across multiple NKG2D-ligand pairs","pmids":["15500864"],"confidence":"High","gaps":["Static structures did not capture force-dependent behavior","Did not link affinity differences to functional discrimination"]},{"year":2004,"claim":"Demonstrated that activating NKG2D output is constrained by inhibitory Ly49 receptors and target MHC class I, establishing integration of opposing NK signals.","evidence":"NK cytotoxicity and cytokine assays titrating H60 against defined Ly49/MHC contexts","pmids":["15328154"],"confidence":"Medium","gaps":["Molecular basis of signal integration not resolved","Single-lab functional assays"]},{"year":2005,"claim":"Showed NKG2D ligands have receptor-independent effects, suppressing T cell proliferation via IL-10 through a non-NKG2D receptor.","evidence":"T cell proliferation assays with IL-10 neutralization and NKG2D-blocking antibodies","pmids":["16091471"],"confidence":"Medium","gaps":["The alternative receptor was not identified","Physiological relevance in vivo unclear"]},{"year":2006,"claim":"Defined the proximal signaling logic: NKG2D couples through DAP10 to PI3K and synergizes with TCR signals as a costimulatory receptor on antigen-specific CD4+ T cells.","evidence":"mAb crosslinking with CFSE proliferation and intracellular cytokine staining on HCMV-specific T cells","pmids":["17109473"],"confidence":"Medium","gaps":["Did not map downstream effector branching","Single-lab functional readouts"]},{"year":2011,"claim":"Mapped the activation pathway downstream of NKG2D-DAP10 to PI3K-AKT-mTOR (S6K1/4E-BP1) and JNK/ERK, and unexpectedly showed cancer cells can express functional NKG2D that drives oncogenic metabolism.","evidence":"Reciprocal Co-IP, phosphorylation and bioenergetics assays with siRNA/overexpression in tumor lines","pmids":["21321202"],"confidence":"High","gaps":["Generality of tumor-intrinsic NKG2D across cancer types not established","Ligand source driving autocrine signaling unclear"]},{"year":2011,"claim":"Distinguished NKG2D costimulation from CD28, showing CD3+NKG2D engagement activates β-catenin/PPARγ and suppresses anti-inflammatory cytokines.","evidence":"Chimeric NKG2D-CD3ζ receptor with β-catenin reporters, cytokine ELISA, siRNA and inhibitors","pmids":["21518928"],"confidence":"Medium","gaps":["Link between DAP10 signaling and β-catenin not mechanistically traced","Chimeric construct may not fully mimic native receptor"]},{"year":2013,"claim":"Connected NKG2D to surveillance of senescent cells and established dual transcriptional control of ligands by the DNA damage response (induction) and ERK (maintenance).","evidence":"In vitro senescence models, NK cytotoxicity, DDR/ERK inhibitors, and NKG2D-knockout mice with liver fibrosis readout","pmids":["26878797"],"confidence":"Medium","gaps":["Transcription factors downstream of DDR/ERK not identified","Single-lab in vivo model"]},{"year":2013,"claim":"Extended NKG2D function beyond surveillance to pathology, showing it is required for allergic pulmonary inflammation via NK-cell granzyme B.","evidence":"NKG2D-knockout mice with NK adoptive transfer epistasis in an HDM allergy model","pmids":["24290277"],"confidence":"High","gaps":["Ligand identity driving lung response not defined","How NK NKG2D engagement promotes allergic priming unclear"]},{"year":2013,"claim":"Documented NKG2D as a costimulatory receptor on senescent T cells in autoimmune vasculitis, linking it to GCA/PMR pathology.","evidence":"Ex vivo proliferation/cytokine assays and temporal artery immunohistology from patients","pmids":["23417963"],"confidence":"Medium","gaps":["Causal contribution to disease not tested by intervention","Ligand source in arterial tissue not defined"]},{"year":2013,"claim":"Identified a druggable axis to boost ligand expression, with spironolactone inducing NKG2D ligands via RXRγ-driven ATM-Chk2 DDR signaling.","evidence":"Nuclear receptor siRNA screen with ATM-Chk2 inhibitors and NK cytotoxicity assays on colon cancer cells","pmids":["24190430"],"confidence":"Medium","gaps":["RXRγ-to-DDR mechanistic link not fully resolved","Single-lab finding"]},{"year":2016,"claim":"Identified CBP/p300 acetyltransferases as epigenetic regulators of basal and stress-induced NKG2D ligand transcription.","evidence":"siRNA knockdown, ChIP for CREB binding and histone acetylation, HDAC inhibitors, and Eμ-Myc lymphoma model","pmids":["27477692"],"confidence":"Medium","gaps":["Upstream signals recruiting CBP/p300 to ligand promoters unclear","Single-lab study"]},{"year":2017,"claim":"Established that the antitumor efficacy of DNA-damaging chemoradiotherapy in glioblastoma operates through DDR-induced NKG2D ligands, and is limited by MGMT.","evidence":"NKG2D-knockout mice and blocking antibodies in syngeneic orthotopic glioblastoma with TMZ/IR","pmids":["29162646"],"confidence":"Medium","gaps":["Which ligands and effector cells dominate not fully partitioned","Single-lab models"]},{"year":2018,"claim":"Revealed a post-transcriptional immune-evasion circuit in which IDO1 drives miR-18a to simultaneously repress NKG2D translation and degrade the ligand Mult-1.","evidence":"AGO2 Co-IP, 3'UTR luciferase reporters, miR-18a gain/loss, and IDO1 inhibitor rescue","pmids":["30268986"],"confidence":"Medium","gaps":["In vivo contribution not established","Whether human ligand 3'UTRs are equivalently targeted unclear"]},{"year":2019,"claim":"Identified PARP1 as a repressor of NKG2D ligands selectively on leukemic stem cells, defining a therapeutic vulnerability via PARP1 inhibition.","evidence":"PARP1 genetic deletion and inhibitors in patient-derived xenotransplants with NK cytotoxicity readouts","pmids":["31316209"],"confidence":"High","gaps":["Mechanism of LSC-selective derepression not fully defined","Durability of NK control in vivo not established"]},{"year":2021,"claim":"Resolved the biophysical basis of ligand discrimination, showing mechanical force selectively stabilizes NKG2D-MICA/MICB via rotational conformational change to set activation thresholds.","evidence":"Live-cell single-molecule force assay, steered molecular dynamics, and mutagenesis","pmids":["34913508"],"confidence":"High","gaps":["How force-tuned lifetimes convert into intracellular signal strength not traced","ULBP force-insensitivity functional consequence not fully explored"]},{"year":2021,"claim":"Extended NKG2D pathology to sterile injury, showing IRI-induced ligands on lung endothelium/epithelium drive NK NKG2D-mediated acute lung injury.","evidence":"NK-deficient mouse rescue, adoptive transfer, and antibody blockade across IRI models","pmids":["33290276"],"confidence":"High","gaps":["Trigger inducing ligands after IRI not defined","Translational blockade window not established"]},{"year":2021,"claim":"Defined β-catenin/TCF4 as a transcriptional repressor of NKG2D ligands (ULBP1/2, Rae-1) in hepatocellular carcinoma, linking oncogenic Wnt to immune escape.","evidence":"RNA-seq, expression profiling, TCF4 ChIP, and β-catenin-activated mouse HCC models","pmids":["33484773"],"confidence":"Medium","gaps":["Direct vs indirect TCF4 repression not fully separated","Whether reversing β-catenin restores NK killing in vivo untested"]},{"year":null,"claim":"How force-tuned receptor binding kinetics are mechanistically transduced through DAP10 into graded PI3K and MAPK signaling, and how the many opposing transcriptional/post-transcriptional ligand controls are integrated in a given tissue context, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking ligand affinity/force to quantitative signal output","Tissue-specific dominance among CBP/p300, PARP1, β-catenin, DDR, and miR-18a regulation unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,2,17,20]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[7,8,20]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2,8]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1,11,12,20]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3,6,8]}],"complexes":["NKG2D-DAP10 receptor complex"],"partners":["DAP10","DAP12","MICA","MICB","ULBP","PIK3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P26718","full_name":"NKG2-D type II integral membrane protein","aliases":["Killer cell lectin-like receptor subfamily K member 1","NK cell receptor D","NKG2-D-activating NK receptor"],"length_aa":216,"mass_kda":25.3,"function":"Functions as an activating and costimulatory receptor involved in immunosurveillance upon binding to various cellular stress-inducible ligands displayed at the surface of autologous tumor cells and virus-infected cells. Provides both stimulatory and costimulatory innate immune responses on activated killer (NK) cells, leading to cytotoxic activity. Acts as a costimulatory receptor for T-cell receptor (TCR) in CD8(+) T-cell-mediated adaptive immune responses by amplifying T-cell activation. Stimulates perforin-mediated elimination of ligand-expressing tumor cells. Signaling involves calcium influx, culminating in the expression of TNF. Participates in NK cell-mediated bone marrow graft rejection. May play a regulatory role in differentiation and survival of NK cells. Binds to ligands belonging to various subfamilies of MHC class I-related glycoproteins including MICA, MICB, RAET1E, RAET1G, RAET1L/ULBP6, ULBP1, ULBP2, ULBP3 (ULBP2>ULBP1>ULBP3) and ULBP4","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P26718/entry"},"depmap":{"release":"DepMap","has_data":false,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KLRK1"},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KLRK1","total_profiled":1310},"omim":[{"mim_id":"618131","title":"IMMUNODEFICIENCY 58; IMD58","url":"https://www.omim.org/entry/618131"},{"mim_id":"617573","title":"C-TYPE LECTIN DOMAIN FAMILY 12, MEMBER B; CLEC12B","url":"https://www.omim.org/entry/617573"},{"mim_id":"611817","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY K, MEMBER 1; KLRK1","url":"https://www.omim.org/entry/611817"},{"mim_id":"610859","title":"CAPPING PROTEIN REGULATOR AND MYOSIN 1 LINKER 2; CARMIL2","url":"https://www.omim.org/entry/610859"},{"mim_id":"609243","title":"RETINOIC ACID EARLY TRANSCRIPT 1E; RAET1E","url":"https://www.omim.org/entry/609243"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":20.8},{"tissue":"lymphoid tissue","ntpm":39.4}],"url":"https://www.proteinatlas.org/search/KLRK1"},"hgnc":{"alias_symbol":["NKG2D","KLR","NKG2-D","CD314"],"prev_symbol":["D12S2489E"]},"alphafold":{"accession":"P26718","domains":[{"cath_id":"3.10.100.10","chopping":"105-215","consensus_level":"high","plddt":96.0536,"start":105,"end":215}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P26718","model_url":"https://alphafold.ebi.ac.uk/files/AF-P26718-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P26718-F1-predicted_aligned_error_v6.png","plddt_mean":79.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KLRK1","jax_strain_url":"https://www.jax.org/strain/search?query=KLRK1"},"sequence":{"accession":"P26718","fasta_url":"https://rest.uniprot.org/uniprotkb/P26718.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P26718/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P26718"}},"corpus_meta":[{"pmid":"12384702","id":"PMC_12384702","title":"Tumour-derived soluble MIC ligands impair expression of NKG2D and T-cell activation.","date":"2002","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/12384702","citation_count":1266,"is_preprint":false},{"pmid":"14523385","id":"PMC_14523385","title":"Roles of the NKG2D immunoreceptor and its ligands.","date":"2003","source":"Nature reviews. 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immunology","url":"https://pubmed.ncbi.nlm.nih.gov/18259774","citation_count":33,"is_preprint":false},{"pmid":"18979516","id":"PMC_18979516","title":"Tumor cell recognition by the NK cell activating receptor NKG2D.","date":"2008","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/18979516","citation_count":31,"is_preprint":false},{"pmid":"16091471","id":"PMC_16091471","title":"NKG2D-independent suppression of T cell proliferation by H60 and MICA.","date":"2005","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16091471","citation_count":29,"is_preprint":false},{"pmid":"32075046","id":"PMC_32075046","title":"Recent Advances in Molecular Mechanisms of the NKG2D Pathway in Hepatocellular Carcinoma.","date":"2020","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/32075046","citation_count":28,"is_preprint":false},{"pmid":"18979514","id":"PMC_18979514","title":"Viral inhibitors of NKG2D ligands: friends or foes of immune surveillance?","date":"2008","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/18979514","citation_count":28,"is_preprint":false},{"pmid":"15500864","id":"PMC_15500864","title":"NKG2D and Related Immunoreceptors.","date":"2004","source":"Advances in protein chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15500864","citation_count":27,"is_preprint":false},{"pmid":"27834580","id":"PMC_27834580","title":"NKG2D ligand expression in pediatric brain tumors.","date":"2016","source":"Cancer biology & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/27834580","citation_count":27,"is_preprint":false},{"pmid":"27477692","id":"PMC_27477692","title":"CBP/p300 acetyltransferases regulate the expression of NKG2D ligands on tumor cells.","date":"2016","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/27477692","citation_count":27,"is_preprint":false},{"pmid":"29316666","id":"PMC_29316666","title":"Fusion Proteins of NKG2D/NKG2DL in Cancer Immunotherapy.","date":"2018","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/29316666","citation_count":26,"is_preprint":false},{"pmid":"28926962","id":"PMC_28926962","title":"Anti-NKG2D mAb: A New Treatment for Crohn's Disease?","date":"2017","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/28926962","citation_count":26,"is_preprint":false},{"pmid":"27783394","id":"PMC_27783394","title":"Association of NKG2D gene variants with susceptibility and severity of rheumatoid arthritis.","date":"2016","source":"Clinical and experimental immunology","url":"https://pubmed.ncbi.nlm.nih.gov/27783394","citation_count":26,"is_preprint":false},{"pmid":"23860405","id":"PMC_23860405","title":"Endothelial cell activation and proliferation modulate NKG2D activity by regulating MICA expression and shedding.","date":"2013","source":"Journal of innate immunity","url":"https://pubmed.ncbi.nlm.nih.gov/23860405","citation_count":26,"is_preprint":false},{"pmid":"37165468","id":"PMC_37165468","title":"Engaging natural killer cells for cancer therapy via NKG2D, CD16A and other receptors.","date":"2023","source":"mAbs","url":"https://pubmed.ncbi.nlm.nih.gov/37165468","citation_count":26,"is_preprint":false},{"pmid":"22843249","id":"PMC_22843249","title":"Immunogenetics of the NKG2D ligand gene family.","date":"2012","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/22843249","citation_count":26,"is_preprint":false},{"pmid":"38139373","id":"PMC_38139373","title":"The Role of NKG2D and Its Ligands in Autoimmune Diseases: New Targets for Immunotherapy.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38139373","citation_count":25,"is_preprint":false},{"pmid":"31655348","id":"PMC_31655348","title":"Expressions of natural cytotoxicity receptor, NKG2D and NKG2D ligands in endometriosis.","date":"2019","source":"Journal of reproductive immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31655348","citation_count":25,"is_preprint":false},{"pmid":"29209320","id":"PMC_29209320","title":"How Mucosal Epithelia Deal with Stress: Role of NKG2D/NKG2D Ligands during Inflammation.","date":"2017","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/29209320","citation_count":24,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":40571,"output_tokens":5339,"usd":0.100899,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13784,"output_tokens":5399,"usd":0.101947,"stage2_stop_reason":"end_turn"},"total_usd":0.202846,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Binding of soluble MIC (shed from tumors) to NKG2D induces endocytosis and degradation of NKG2D on T cells, causing systemic downregulation of NKG2D expression on tumor-infiltrating and peripheral blood T cells and impairing effector T cell responsiveness.\",\n      \"method\": \"Flow cytometry of patient samples, in vitro endocytosis/degradation assays, correlation of circulating soluble MICA with NKG2D levels\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional assays, patient samples correlated with in vitro mechanism, replicated concept across multiple labs\",\n      \"pmids\": [\"12384702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Ectopic expression of murine NKG2D ligands Rae1β or H60 on tumor cell lines causes potent rejection by syngeneic mice mediated by NK cells and/or CD8+ T cells, directly linking NKG2D ligand expression to tumor rejection and priming of cytotoxic T cells and NK cell sensitization in vivo.\",\n      \"method\": \"In vivo syngeneic tumor rejection assays, adoptive transfer, NK cell depletion experiments\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic/cellular epistasis with depletion experiments, replicated across multiple tumor lines\",\n      \"pmids\": [\"11557981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"NKG2D (human) transmits signals via its association with the DAP10 adapter subunit, coupling to phosphoinositide 3-kinase (PI3K); in mice, alternatively spliced isoforms signal through either DAP10 or DAP12.\",\n      \"method\": \"Biochemical co-immunoprecipitation, signaling assays, splice-isoform analysis\",\n      \"journal\": \"Cancer immunology research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — DAP10/DAP12 association replicated across multiple studies and labs\",\n      \"pmids\": [\"26041808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Cancer cells themselves express NKG2D in complex with DAP10; triggering NKG2D on these cancer cells activates the PI3K–AKT–mTOR oncogenic signaling axis and downstream effectors S6K1 and 4E-BP1, as well as JNK and ERK MAP kinase cascades, increasing bioenergetic metabolism and proliferation of tumor cells.\",\n      \"method\": \"Immunoprecipitation, phosphorylation assays, siRNA knockdown, overexpression in tumor lines, bioenergetics measurements\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, multiple signaling readouts, functional rescue, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"21321202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NKG2D discriminates between its ligands through selective mechanical force-induced conformational changes: force application selectively prolongs NKG2D interaction lifetimes with MICA and MICB (but not ULBPs), with MICA undergoing force-induced rotational conformational changes that form additional hydrogen bonds at the NKG2D interface, impeding dissociation under force and determining downstream NK cell activation.\",\n      \"method\": \"Live-cell single-molecule biomechanical assay, steered molecular dynamics simulations, mutagenesis, in situ binding kinetics\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule force assay combined with molecular dynamics simulation and mutagenesis in one rigorous study\",\n      \"pmids\": [\"34913508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"NKG2D-mediated cytotoxicity and cytokine secretion are regulated by inhibitory Ly49 receptors (Ly49A/G and Ly49C/I) in a manner dependent on both H60 expression level and MHC class I identity on target cells; even high H60 expression cannot overcome Ly49A/G inhibition, establishing epistatic crosstalk between activating NKG2D and inhibitory receptors.\",\n      \"method\": \"NK cell cytotoxicity assays with antibody crosslinking, IFN-γ/GM-CSF secretion assays, titration of H60 expression on target cells\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays with defined receptor manipulations, single lab, multiple ligand levels tested\",\n      \"pmids\": [\"15328154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Resveratrol enhances NK cell cytotoxicity through NKG2D-dependent JNK and ERK-1/2 MAP kinase pathways, leading to increased perforin expression; siRNA knockdown of JNK-1 or ERK-2 abolishes the resveratrol-enhanced cytotoxicity.\",\n      \"method\": \"NK92 cell culture, siRNA knockdown of JNK-1/ERK-2, kinase inhibitor treatments, cytotoxicity assays, perforin western blot\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown plus pharmacological inhibitors with multiple readouts, single lab\",\n      \"pmids\": [\"20082299\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Simultaneous stimulation of CD8+ T cells through CD3 and NKG2D (or a chimeric NKG2D-CD3ζ receptor) activates β-catenin signaling and suppresses production of anti-inflammatory cytokines (IL-10, IL-9, IL-13, VEGF-α) in a β-catenin- and PPARγ-dependent manner, distinct from TCR+CD28 costimulation.\",\n      \"method\": \"Chimeric receptor expression, β-catenin reporter assays, cytokine ELISA, siRNA, pharmacological inhibition\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — chimeric receptor approach combined with siRNA and inhibitors, single lab\",\n      \"pmids\": [\"21518928\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Human NKG2D is coupled by the DAP10 adapter to phosphoinositide 3-kinase (PI3K) and specifically interacts with stress-inducible ligands (MICA, MICB, ULBP); on CD4+ T cells specific for human cytomegalovirus, NKG2D engagement synergizes with TCR-dependent activation, triggering proliferation and cytokine production (IFN-γ, TNF-α), functioning as a costimulatory receptor.\",\n      \"method\": \"Flow cytometry, CFSE proliferation assay, intracellular cytokine staining, mAb crosslinking of NKG2D\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays with antibody crosslinking, single lab, multiple readouts\",\n      \"pmids\": [\"17109473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NKG2D ligand expression on senescent cells (MICA and ULBP2) is necessary for efficient NK-mediated cytotoxicity toward senescent fibroblasts; initial NKG2D ligand expression in senescence depends on the DNA damage response, while continuous expression is regulated by the ERK signaling pathway. In mice lacking NKG2D, senescent liver stellate cells accumulate and liver fibrosis is increased.\",\n      \"method\": \"In vitro senescence models, NK cytotoxicity assays, NKG2D-knockout mice, liver fibrosis histology, ERK/DDR pathway inhibitors\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — NKG2D knockout in vivo combined with in vitro mechanistic dissection, single lab\",\n      \"pmids\": [\"26878797\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PARP1 represses expression of NKG2D ligands on leukemic stem cells (LSCs); genetic or pharmacological inhibition of PARP1 induces NKG2DL on the LSC surface (but not on healthy or pre-leukemic cells), rendering LSCs susceptible to NK cell killing and suppressing leukemogenesis in patient-derived xenotransplant models.\",\n      \"method\": \"PARP1 genetic deletion, PARP1 inhibitor treatment, patient-derived xenotransplant models, NK cell cytotoxicity assays, flow cytometry\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic and pharmacological perturbation of identified writer (PARP1), validated in patient-derived in vivo model with multiple orthogonal approaches\",\n      \"pmids\": [\"31316209\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NK cell NKG2D and granzyme B are both required for HDM-induced allergic pulmonary inflammation; NKG2D-deficient mice are resistant to allergic inflammation, and adoptive transfer of wild-type NK cells (but not CD3+ T cells) restores the response only if the NK cells express granzyme B.\",\n      \"method\": \"NKG2D-knockout mouse model, adoptive transfer of NK cells, HDM-induced allergy model, lung histology, IgE measurement\",\n      \"journal\": \"The Journal of allergy and clinical immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — NKG2D KO combined with adoptive transfer epistasis, multiple phenotypic readouts, granzyme B requirement defined\",\n      \"pmids\": [\"24290277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NKG2D ligands are induced on lung endothelial and epithelial cells following ischemia-reperfusion injury; NK cell NKG2D receptor ligation mediates acute lung injury, as antibody-mediated NKG2D blockade or NK cell depletion abrogates injury in mouse models.\",\n      \"method\": \"NK cell-deficient mouse strain, adoptive transfer, antibody blockade, IRI mouse models, NK cell trafficking/maturation analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — NK cell-deficient strain rescue, adoptive transfer, and antibody blockade all converge, multiple models\",\n      \"pmids\": [\"33290276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CBP/p300 acetyltransferases regulate basal and stress-induced expression of NKG2D ligands (MICA/B, ULBP2, RAE-1) on tumor cells; loss of CBP/p300 reduces surface NKG2D ligand expression and NK cell-mediated killing; CREB binding and histone acetylation at NKG2D ligand promoters are increased during upregulation.\",\n      \"method\": \"siRNA knockdown of CBP/p300, ChIP assay, HDAC inhibitor treatment, NK cytotoxicity assays, Eμ-Myc mouse lymphoma model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and functional rescue, in vitro and in vivo validation, single lab\",\n      \"pmids\": [\"27477692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Spironolactone upregulates NKG2D ligand expression on colon cancer cells through the ATM-Chk2-mediated DNA damage checkpoint pathway via RXRγ activation (not the mineralocorticoid receptor), enhancing NK cell-mediated tumor elimination.\",\n      \"method\": \"siRNA library screen of nuclear hormone receptors, ATM-Chk2 pathway inhibitors, NKG2DL expression assays, NK cytotoxicity assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA screen identified RXRγ as the mediator, confirmed with pathway inhibitors and functional NK killing assay, single lab\",\n      \"pmids\": [\"24190430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"β-catenin signaling (via CTNNB1 mutation) downregulates expression of ULBP1 and ULBP2 NKG2D ligands in hepatocellular carcinoma; in mouse HCC models, β-catenin signaling reduces Rae-1 expression through TCF4 binding at ligand promoters.\",\n      \"method\": \"RNA-seq, TaqMan expression profiling, ChIP (TCF4 binding), mouse HCC models with β-catenin activation\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP identifying transcription factor binding combined with mouse in vivo model, single lab\",\n      \"pmids\": [\"33484773\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"H60 and MICA can suppress T cell proliferation through a receptor other than NKG2D in an IL-10-dependent manner, demonstrating that NKG2D ligands can mediate inhibitory effects on T cells independent of the NKG2D receptor itself.\",\n      \"method\": \"T cell proliferation assays with IL-10 neutralization, NKG2D-blocking antibodies, loss-of-function experiments\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — NKG2D-blocking antibody controls with IL-10 neutralization, single lab, two orthogonal methods\",\n      \"pmids\": [\"16091471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"NKG2D is a homodimeric C-type lectin-like receptor that interacts with asymmetric monomeric ligands in 2:1 complexes; each NKG2D monomer uses an equivalent surface to bind structurally divergent ligand surfaces through 'rigid adaptation' rather than induced-fit, explaining recognition degeneracy.\",\n      \"method\": \"Crystal structure analysis, thermodynamic and kinetic analyses of multiple NKG2D-ligand pairs\",\n      \"journal\": \"Advances in protein chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple crystal structures combined with thermodynamic and kinetic analyses across multiple ligand pairs\",\n      \"pmids\": [\"15500864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IDO1 promotes expression of miR-18a, which directly downregulates NKG2D (via its 3'UTR) and the NKG2D ligand Mult-1 (via its 3'UTR); IDO1 promotes binding of miR-18a to AGO2, leading to degradation of Mult-1 mRNA and inhibition of NKG2D translation, thereby impairing NK cell cytotoxicity.\",\n      \"method\": \"Co-immunoprecipitation of AGO2, 3'UTR luciferase reporter assays, miR-18a overexpression/inhibition, INCB024360 treatment, IDO1 overexpression\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — AGO2 Co-IP, 3'UTR binding assays, pharmacological rescue, single lab\",\n      \"pmids\": [\"30268986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NKG2D-dependent antitumor effects of temozolomide (TMZ) and irradiation (IR) in glioblastoma require an intact DNA damage response and are attenuated by MGMT; blocking NKG2D pathway or using NKG2D-knockout mice reduces the survival benefit of TMZ or IR in syngeneic orthotopic glioblastoma models.\",\n      \"method\": \"NKG2D-knockout mouse model, NKG2D-blocking antibodies, syngeneic orthotopic glioblastoma model, in vitro DDR pathway analysis\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — NKG2D KO plus antibody blockade in vivo, multiple glioblastoma models, single lab\",\n      \"pmids\": [\"29162646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NKG2D signaling in human CD8+ T cells co-stimulates TCR activation; on NK cells, NKG2D can act as a primary activation receptor sufficient to trigger cytotoxicity.\",\n      \"method\": \"Antibody crosslinking, cytotoxicity assays, cytokine secretion assays comparing NK vs. T cell responses\",\n      \"journal\": \"Current opinion in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Strong — replicated across multiple labs using antibody crosslinking and functional assays\",\n      \"pmids\": [\"11973127\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NKG2D in T cells (NKG2D cross-linkage) augments anti-CD3-triggered proliferation and IFN-γ/TNF-α production in CD8 T cells; in GCA and PMR patients, NKG2D is preferentially expressed on senescent CD4+CD28- and CD8+ T cells and NKG2D ligands are present in temporal arteries, supporting a costimulatory role in autoimmune vasculitis.\",\n      \"method\": \"Flow cytometry, CFSE proliferation assay, intracellular cytokine staining, immunofluorescence and immunohistology of temporal artery biopsies\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ex vivo functional assays with tissue validation, single lab\",\n      \"pmids\": [\"23417963\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KLRK1/NKG2D is a homodimeric C-type lectin-like activating receptor expressed on NK cells, CD8+ T cells, and subsets of other T cells that signals through DAP10 (and DAP12 in mice) to activate PI3K–AKT–mTOR and MAP kinase (JNK, ERK) pathways upon binding a diverse repertoire of stress-induced MHC class I-like ligands (MICA, MICB, ULBPs in humans; Rae-1, H60, Mult1 in mice); it discriminates ligands through selective force-dependent conformational changes (MICA/MICB more than ULBPs), functions as a primary activation receptor on NK cells and a costimulatory receptor on T cells, is downregulated by ligand-induced endocytosis and degradation, and its ligands are regulated transcriptionally (e.g., by CBP/p300, β-catenin/TCF4), post-translationally (proteolytic shedding, exosome release), and by upstream pathways including DNA damage response, PARP1, and IDO1/miR-18a, with soluble shed ligands acting as immune decoys that blunt NKG2D-mediated immunosurveillance.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KLRK1/NKG2D is a homodimeric C-type lectin-like activating receptor of NK cells and CD8+ T cells that couples recognition of stress-induced MHC class I-like ligands to cytotoxicity, cytokine production, and tumor immunosurveillance [#1, #17, #20]. Structurally, it binds asymmetric monomeric ligands (MICA, MICB, ULBPs in humans; Rae-1, H60, Mult1 in mice) in 2:1 complexes, each monomer using an equivalent surface to engage divergent ligands by 'rigid adaptation' rather than induced fit, which explains its recognition degeneracy [#17]; ligand discrimination is further refined by mechanical force, which selectively prolongs interaction lifetimes with MICA/MICB through force-induced rotational conformational changes that strengthen the interface, while ULBP binding is force-insensitive [#4]. Signaling proceeds through the DAP10 adapter (DAP10 or DAP12 in mouse splice isoforms), coupling to PI3K-AKT-mTOR and to JNK/ERK MAP kinase cascades to drive perforin-dependent cytotoxicity [#2, #6, #8]. Functionally NKG2D operates as a primary activation receptor on NK cells and as a costimulatory receptor on T cells, augmenting TCR/CD3 signaling and proliferation and engaging \\u03b2-catenin/PPAR\\u03b3 programs distinct from CD28 costimulation [#7, #8, #20]. Its activity is tuned by epistatic crosstalk with inhibitory Ly49 receptors, by ligand-induced endocytosis and degradation of the receptor triggered by soluble shed MIC, and by IDO1-driven miR-18a that directly represses NKG2D and its ligand Mult-1 [#0, #5, #18]. NKG2D ligand abundance is itself a tightly regulated checkpoint: ligands are induced through the DNA damage response and ERK signaling and by CBP/p300 acetyltransferases, and repressed by PARP1 and by \\u03b2-catenin/TCF4, defining the tumor and senescent-cell contexts in which NKG2D enables killing [#9, #10, #13, #15]. Beyond surveillance of tumors and senescent cells, NKG2D engagement drives pathology in allergic pulmonary inflammation and ischemia-reperfusion lung injury and underlies costimulation in autoimmune vasculitis [#11, #12, #21].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established that NKG2D ligand expression on a target cell is sufficient to trigger immune rejection in vivo, linking the receptor directly to tumor elimination.\",\n      \"evidence\": \"Ectopic Rae1\\u03b2/H60 expression on syngeneic tumor lines with NK depletion and adoptive transfer in mice\",\n      \"pmids\": [\"11557981\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the receptor's signaling subunit\", \"Relative NK vs CD8+ T cell contribution not fully partitioned\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Revealed a tumor immune-evasion mechanism: soluble shed ligand engages NKG2D to drive its endocytosis and degradation, downregulating receptor surface levels and impairing effector responsiveness.\",\n      \"evidence\": \"Flow cytometry of patient samples correlated with in vitro endocytosis/degradation assays\",\n      \"pmids\": [\"12384702\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endocytic trafficking machinery not defined\", \"Whether shedding kinetics differ across ligands not addressed\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Explained how a single receptor recognizes structurally divergent ligands by showing 2:1 homodimeric binding via rigid adaptation rather than induced fit.\",\n      \"evidence\": \"Crystal structures with thermodynamic and kinetic analyses across multiple NKG2D-ligand pairs\",\n      \"pmids\": [\"15500864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Static structures did not capture force-dependent behavior\", \"Did not link affinity differences to functional discrimination\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrated that activating NKG2D output is constrained by inhibitory Ly49 receptors and target MHC class I, establishing integration of opposing NK signals.\",\n      \"evidence\": \"NK cytotoxicity and cytokine assays titrating H60 against defined Ly49/MHC contexts\",\n      \"pmids\": [\"15328154\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of signal integration not resolved\", \"Single-lab functional assays\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showed NKG2D ligands have receptor-independent effects, suppressing T cell proliferation via IL-10 through a non-NKG2D receptor.\",\n      \"evidence\": \"T cell proliferation assays with IL-10 neutralization and NKG2D-blocking antibodies\",\n      \"pmids\": [\"16091471\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The alternative receptor was not identified\", \"Physiological relevance in vivo unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined the proximal signaling logic: NKG2D couples through DAP10 to PI3K and synergizes with TCR signals as a costimulatory receptor on antigen-specific CD4+ T cells.\",\n      \"evidence\": \"mAb crosslinking with CFSE proliferation and intracellular cytokine staining on HCMV-specific T cells\",\n      \"pmids\": [\"17109473\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not map downstream effector branching\", \"Single-lab functional readouts\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Mapped the activation pathway downstream of NKG2D-DAP10 to PI3K-AKT-mTOR (S6K1/4E-BP1) and JNK/ERK, and unexpectedly showed cancer cells can express functional NKG2D that drives oncogenic metabolism.\",\n      \"evidence\": \"Reciprocal Co-IP, phosphorylation and bioenergetics assays with siRNA/overexpression in tumor lines\",\n      \"pmids\": [\"21321202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of tumor-intrinsic NKG2D across cancer types not established\", \"Ligand source driving autocrine signaling unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Distinguished NKG2D costimulation from CD28, showing CD3+NKG2D engagement activates \\u03b2-catenin/PPAR\\u03b3 and suppresses anti-inflammatory cytokines.\",\n      \"evidence\": \"Chimeric NKG2D-CD3\\u03b6 receptor with \\u03b2-catenin reporters, cytokine ELISA, siRNA and inhibitors\",\n      \"pmids\": [\"21518928\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Link between DAP10 signaling and \\u03b2-catenin not mechanistically traced\", \"Chimeric construct may not fully mimic native receptor\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Connected NKG2D to surveillance of senescent cells and established dual transcriptional control of ligands by the DNA damage response (induction) and ERK (maintenance).\",\n      \"evidence\": \"In vitro senescence models, NK cytotoxicity, DDR/ERK inhibitors, and NKG2D-knockout mice with liver fibrosis readout\",\n      \"pmids\": [\"26878797\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factors downstream of DDR/ERK not identified\", \"Single-lab in vivo model\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended NKG2D function beyond surveillance to pathology, showing it is required for allergic pulmonary inflammation via NK-cell granzyme B.\",\n      \"evidence\": \"NKG2D-knockout mice with NK adoptive transfer epistasis in an HDM allergy model\",\n      \"pmids\": [\"24290277\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ligand identity driving lung response not defined\", \"How NK NKG2D engagement promotes allergic priming unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Documented NKG2D as a costimulatory receptor on senescent T cells in autoimmune vasculitis, linking it to GCA/PMR pathology.\",\n      \"evidence\": \"Ex vivo proliferation/cytokine assays and temporal artery immunohistology from patients\",\n      \"pmids\": [\"23417963\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal contribution to disease not tested by intervention\", \"Ligand source in arterial tissue not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified a druggable axis to boost ligand expression, with spironolactone inducing NKG2D ligands via RXR\\u03b3-driven ATM-Chk2 DDR signaling.\",\n      \"evidence\": \"Nuclear receptor siRNA screen with ATM-Chk2 inhibitors and NK cytotoxicity assays on colon cancer cells\",\n      \"pmids\": [\"24190430\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"RXR\\u03b3-to-DDR mechanistic link not fully resolved\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified CBP/p300 acetyltransferases as epigenetic regulators of basal and stress-induced NKG2D ligand transcription.\",\n      \"evidence\": \"siRNA knockdown, ChIP for CREB binding and histone acetylation, HDAC inhibitors, and E\\u03bc-Myc lymphoma model\",\n      \"pmids\": [\"27477692\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Upstream signals recruiting CBP/p300 to ligand promoters unclear\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established that the antitumor efficacy of DNA-damaging chemoradiotherapy in glioblastoma operates through DDR-induced NKG2D ligands, and is limited by MGMT.\",\n      \"evidence\": \"NKG2D-knockout mice and blocking antibodies in syngeneic orthotopic glioblastoma with TMZ/IR\",\n      \"pmids\": [\"29162646\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which ligands and effector cells dominate not fully partitioned\", \"Single-lab models\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed a post-transcriptional immune-evasion circuit in which IDO1 drives miR-18a to simultaneously repress NKG2D translation and degrade the ligand Mult-1.\",\n      \"evidence\": \"AGO2 Co-IP, 3'UTR luciferase reporters, miR-18a gain/loss, and IDO1 inhibitor rescue\",\n      \"pmids\": [\"30268986\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo contribution not established\", \"Whether human ligand 3'UTRs are equivalently targeted unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified PARP1 as a repressor of NKG2D ligands selectively on leukemic stem cells, defining a therapeutic vulnerability via PARP1 inhibition.\",\n      \"evidence\": \"PARP1 genetic deletion and inhibitors in patient-derived xenotransplants with NK cytotoxicity readouts\",\n      \"pmids\": [\"31316209\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of LSC-selective derepression not fully defined\", \"Durability of NK control in vivo not established\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the biophysical basis of ligand discrimination, showing mechanical force selectively stabilizes NKG2D-MICA/MICB via rotational conformational change to set activation thresholds.\",\n      \"evidence\": \"Live-cell single-molecule force assay, steered molecular dynamics, and mutagenesis\",\n      \"pmids\": [\"34913508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How force-tuned lifetimes convert into intracellular signal strength not traced\", \"ULBP force-insensitivity functional consequence not fully explored\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended NKG2D pathology to sterile injury, showing IRI-induced ligands on lung endothelium/epithelium drive NK NKG2D-mediated acute lung injury.\",\n      \"evidence\": \"NK-deficient mouse rescue, adoptive transfer, and antibody blockade across IRI models\",\n      \"pmids\": [\"33290276\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trigger inducing ligands after IRI not defined\", \"Translational blockade window not established\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined \\u03b2-catenin/TCF4 as a transcriptional repressor of NKG2D ligands (ULBP1/2, Rae-1) in hepatocellular carcinoma, linking oncogenic Wnt to immune escape.\",\n      \"evidence\": \"RNA-seq, expression profiling, TCF4 ChIP, and \\u03b2-catenin-activated mouse HCC models\",\n      \"pmids\": [\"33484773\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect TCF4 repression not fully separated\", \"Whether reversing \\u03b2-catenin restores NK killing in vivo untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How force-tuned receptor binding kinetics are mechanistically transduced through DAP10 into graded PI3K and MAPK signaling, and how the many opposing transcriptional/post-transcriptional ligand controls are integrated in a given tissue context, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking ligand affinity/force to quantitative signal output\", \"Tissue-specific dominance among CBP/p300, PARP1, \\u03b2-catenin, DDR, and miR-18a regulation unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2, 17, 20]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [7, 8, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1, 11, 12, 20]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3, 6, 8]}\n    ],\n    \"complexes\": [\"NKG2D-DAP10 receptor complex\"],\n    \"partners\": [\"DAP10\", \"DAP12\", \"MICA\", \"MICB\", \"ULBP\", \"PIK3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}