{"gene":"ITGA1","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":1985,"finding":"VLA-1 (ITGA1/CD49a) is a heterodimeric protein complex composed of an Mr 210,000 alpha-1 subunit in acid-labile association with an Mr 130,000 beta subunit, forming a 1:1 stoichiometric heterodimer on activated T cells. The alpha-1 and beta subunits contain substantial sialic acid and N-linked carbohydrate, and are highly non-homologous to each other by peptide mapping.","method":"Cross-linking experiments, immunoprecipitation, SDS-PAGE, neuraminidase/endoglycosidase F digestion, one-dimensional peptide mapping","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical reconstitution and characterization with multiple orthogonal methods in a focused study","pmids":["2415516"],"is_preprint":false},{"year":1990,"finding":"Purified VLA-1 integrin from human smooth muscle (195 kD alpha + 130 kD beta subunits) binds type I, II, III, and IV collagens, C1q, and laminin in a Ca2+/Mg2+-dependent manner via liposome adhesion assays. It does not bind gelatin, fibronectin, or thrombospondin.","method":"Affinity chromatography on collagen-Sepharose, liposome adhesion assay, quantitative immunoblotting","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — purified protein reconstituted into liposomes and tested against multiple substrates with divalent cation dependence established","pmids":["2229189"],"is_preprint":false},{"year":1991,"finding":"Purified VLA-1 from human smooth muscle interacts with interstitial collagens (types I, II, III) and basement membrane proteins (type IV collagen and laminin) via a Ca2+/Mg2+-dependent mechanism in liposome assays; does not interact with fibronectin, thrombospondin, or albumin. The RGD peptide does not inhibit binding, indicating a non-RGD binding mechanism. Denaturation of type I collagen reduces binding 5–7-fold.","method":"Liposome binding assay with purified VLA-1 integrin, inhibition experiments with RGD peptide and cation chelation","journal":"Biokhimiia (Moscow, Russia)","confidence":"High","confidence_rationale":"Tier 1 / Strong — purified protein in liposome reconstitution assay, replicated substrate specificity findings from concurrent work","pmids":["1807406"],"is_preprint":false},{"year":1987,"finding":"VLA-1 expression on T cells is downregulated by mitogenic stimulation (PHA, ConA) in a reversible manner, whereas VLA-2 is not similarly suppressed. Repetitive restimulation with alloantigen or anti-CD3 increases the VLA-2:VLA-1 ratio. These changes are intrinsic to homogeneous T cell lines, not due to subpopulation shifts, indicating cell-cycle/activation-state-dependent regulation of VLA-1 expression.","method":"Flow cytometry, immunoprecipitation of T cell lines under defined stimulation conditions","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean cell-line experiments with defined stimuli, two orthogonal detection methods, single lab","pmids":["3106495"],"is_preprint":false},{"year":1988,"finding":"Cell quiescence induced by low serum (0.5%) causes a 10–28-fold increase in VLA-1 expression on normal human fibroblasts with a corresponding decrease in VLA-2 and VLA-3. These changes are reversible upon re-stimulation with serum and persist after proliferation has stopped, indicating that VLA-1 upregulation is linked to quiescence rather than cell-cycle transitions per se.","method":"Flow cytometry, immunoprecipitation, quantitative comparison under defined serum conditions","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative flow cytometry and immunoprecipitation, two methods, single lab","pmids":["3292271"],"is_preprint":false},{"year":1994,"finding":"VLA-1-mediated adhesion of NB100 neuroblastoma cells to collagen type I is supported by Mg2+ (mM) or Mn2+ (µM) but not Ca2+ alone; Ca2+ inhibits Mg2+-supported adhesion. VLA-1 can be directly activated by the stimulatory anti-β1 monoclonal antibody TS2/16 to promote collagen adhesion.","method":"Cell adhesion assay with divalent cation manipulation, blocking antibody experiments, monoclonal antibody activation","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional assay with pharmacological and antibody interventions, single lab, multiple conditions tested","pmids":["7516898"],"is_preprint":false},{"year":1994,"finding":"VLA-1 (CD49a) on T cells functions as a specific collagen IV receptor: antibody blockade of CD49a (mAb 1B3.1) inhibited adhesion to collagen IV but not fibronectin, and Mg2+ supported VLA-1-mediated spreading on collagen IV. Cross-linking of VLA-1 with plastic-bound antibody selectively induced IL-2R expression on γδ T cell clones, demonstrating VLA-1 can transduce intracellular signals.","method":"Cell adhesion assay, antibody blocking, cation manipulation, IL-2R expression by flow cytometry","journal":"Cellular immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional adhesion and signaling assays with specific blocking mAb, single lab","pmids":["8025956"],"is_preprint":false},{"year":1995,"finding":"In glomerular epithelial cells (GEC), VLA-1 and VLA-2 cooperate for adhesion to laminin, while only VLA-2 is used for collagen adhesion. In mesangial cells, VLA-1 is the primary laminin receptor and both VLA-1 and VLA-2 support collagen adhesion. This demonstrates cell-type-specific modulation of VLA-1 ligand binding specificity.","method":"Monoclonal antibody blocking of cell adhesion to extracellular matrix proteins, ELISA, immunocytochemistry","journal":"Laboratory investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional blocking antibody adhesion assays on two distinct cell types, single lab","pmids":["7898055"],"is_preprint":false},{"year":1999,"finding":"Integrin alpha1beta1 (VLA-1) is the primary collagen receptor on human intestinal intraepithelial lymphocytes (IELs): antibody blockade of alpha1 (CD49a) and beta1 subunits inhibited IEL adhesion to collagen type I by ~82% and to type IV by ~94%. Adhesion was upregulated by PKC stimulation (phorbol ester) and was dependent on divalent cations (Mn2+/Mg2+ supportive, Ca2+ inhibitory), consistent with canonical integrin activation.","method":"51Cr-labeled cell adhesion assay, antibody blocking, pharmacological stimulation (PKC activators/inhibitors), divalent cation manipulation","journal":"Immunology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — quantitative radioactive adhesion assay with specific antibody blockade and multiple mechanistic interventions, findings consistent with parallel studies","pmids":["10457223"],"is_preprint":false},{"year":2000,"finding":"VLA-1 null mice have a ~50% reduction in gut intraepithelial lymphocytes (IELs) with normal peripheral blood and lymphoid organ lymphocyte distribution and unchanged γδ:αβ IEL ratios. IL-2-stimulated splenocytes from VLA-1 null mice show deficient adhesion to fibrillar and basement membrane collagen and reduced proliferation on collagen substratum, demonstrating that VLA-1 is required for IEL maintenance in the gut and for collagen-dependent T cell proliferation.","method":"Genetic knockout mouse (VLA-1 null), cell counting, adhesion assays, proliferation assays","journal":"Cellular immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout phenotype with specific cellular and functional readouts, in vivo and in vitro","pmids":["10805967"],"is_preprint":false},{"year":2004,"finding":"VLA-1 (alpha1beta1 integrin) is required for retention of influenza-specific CD8 memory T cells in the lung and nonlymphoid tissues. Antibody blockade or genetic deficiency of VLA-1 decreased virus-specific CTL in lung and other nonlymphoid tissues while increasing them in the spleen, and impaired secondary heterosubtypic immunity, demonstrating that VLA-1 mediates T cell retention in tissues via ECM attachment.","method":"Antibody blockade, genetic knockout mice, flow cytometry, challenge infection model, tissue distribution analysis","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — both antibody blockade and genetic deficiency converge on the same phenotype, with in vivo functional consequence","pmids":["14975239"],"is_preprint":false},{"year":2007,"finding":"The ITGA1 gene locus is regulated by DNA CpG methylation: the ITGA1 promoter is fully methylated at 19 CpG sites in megakaryocytic (MK) cells that do not express alpha1beta1, and completely demethylated in expressing cells. In vitro methylation of ITGA1 suppresses transcription. Treatment with the DNA demethylating agent 5-aza-2'-deoxycytidine (but not the HDAC inhibitor Trichostatin A) induces de novo ITGA1 expression in MK cells. Progressive CpG methylation of ITGA1 occurs during thrombopoietin-induced megakaryocyte differentiation. The ITGA1 promoter also contains a CArG box bound by serum response factor (SRF).","method":"Sodium bisulfite genomic sequencing, promoter-LUC reporter assays, 5-aza-2'-deoxycytidine treatment, qPCR, Northern blot, transcription factor binding analysis","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (bisulfite sequencing, reporter assay, pharmacological demethylation, differentiation time course) in a single rigorous study","pmids":["17669516"],"is_preprint":false},{"year":2002,"finding":"VLA-1 antibody blockade in a rat model of crescentic glomerulonephritis reduced glomerular and tubulointerstitial scarring, decreased type IV collagen and ED(A) fibronectin deposition, and increased matrix metalloproteinase-9 expression in glomeruli. This demonstrates that VLA-1 mediates renal fibrosis, and that its neutralization promotes matrix degradation via MMP-9 upregulation.","method":"Monoclonal antibody treatment in vivo (rat model), histology, immunohistochemistry, biochemical markers","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo antibody neutralization with defined structural and biochemical readouts, single lab","pmids":["12368200"],"is_preprint":false},{"year":2010,"finding":"VLA-1 (alpha1beta1) is required for the accumulation of CD4+ tissue memory T cells in the airways after influenza infection. Fewer memory/effector CD4+ T cells were recovered from airways of alpha1-/- mice but lymphoid tissues were unaffected. Airway CD49a+CD4+ cells expressed reduced apoptosis markers and provided rapid IFN-γ responses upon secondary challenge.","method":"Genetic knockout mice (alpha1-/-), flow cytometry, intracellular cytokine staining, apoptosis markers, secondary challenge infection model","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout phenotype with specific tissue-compartment readout and functional secondary challenge, consistent with parallel CD8 T cell findings","pmids":["20200271"],"is_preprint":false},{"year":1995,"finding":"LPS and IFN-γ rapidly induce de novo expression of alpha1/beta1 (VLA-1) integrin on monocytes, detectable on the membrane within 12 hours, with induction of alpha1 mRNA. This induction is dependent on the cellular redox state (inhibited by antioxidants). Monocyte-deactivating cytokines (IL-4, IL-10) only minimally inhibit this upregulation.","method":"Flow cytometry, Northern blot, pharmacological inhibition with antioxidants and cytokines","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Northern blot and flow cytometry, specific induction conditions tested, single lab","pmids":["7589148"],"is_preprint":false},{"year":2002,"finding":"VLA-1 on MS patient-derived, myelin antigen-reactive T cell lines mediates adhesion to collagen IV (the major collagenous constituent of vascular basement membranes) and active transmigration through collagen IV gels toward TNF-α; both processes were inhibited almost completely by anti-VLA-1 mAb. Ionizing radiation abrogated VLA-1-mediated collagen IV adhesion, suggesting radiation-induced integrin clustering impairs VLA-1 function.","method":"Cell adhesion assay, transwell transmigration assay, antibody blocking, irradiation experiments, immunofluorescence of integrin clustering","journal":"Journal of clinical immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional assays with specific antibody blockade, single lab, two orthogonal assays","pmids":["12078857"],"is_preprint":false},{"year":2017,"finding":"ITGA1 (integrin alpha1) is required for collagen-induced tumorigenic potential in pancreatic ductal adenocarcinoma (PDAC) cells. ITGA1 depletion impairs collagen/ITGA1 signaling that supports survival of ALDH1+ stem-like cancer cells and cooperates with TGFβ to drive gemcitabine resistance. ITGA1 is also required for TGFβ/collagen-induced EMT and metastasis.","method":"siRNA/shRNA knockdown of ITGA1, colony/invasion assays, stem cell marker analysis (ALDH1), drug resistance assays, metastasis assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with multiple defined phenotypic readouts, single lab","pmids":["28855593"],"is_preprint":false},{"year":2017,"finding":"E2F1 transcription factor directly upregulates ITGA1 expression in hepatocellular carcinoma cells, as demonstrated by dual luciferase reporter assay and chromatin immunoprecipitation. d-ICD inhibits E2F1 expression and thereby suppresses ITGA1-mediated HCC cell migration and invasion.","method":"Dual luciferase reporter assay, chromatin immunoprecipitation (ChIP), wound healing assay, transwell invasion assay, Western blot, qRT-PCR","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct transcription factor binding demonstrated by ChIP and luciferase reporter, two orthogonal methods, single lab","pmids":["28264467"],"is_preprint":false},{"year":2019,"finding":"CD49a (ITGA1) on human decidual NK cells suppresses cytotoxicity: CD49a neutralizing antibody upregulated perforin, granzyme B, and IFN-γ expression, increased killing activity (51Cr release assay), and downregulated dNK cell migration and adhesion. A newly identified lncRNA (lnc-49a) was shown to positively regulate CD49a expression in primary human NK cells.","method":"CD49a neutralizing antibody, flow cytometry, 51Cr release cytotoxicity assay, lncRNA microarray, primary human NK cells","journal":"American journal of reproductive immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional neutralization with specific cytotoxicity assay and mechanistic lncRNA regulator identification, single lab","pmids":["30756436"],"is_preprint":false},{"year":2020,"finding":"CD49a (integrin alpha1) on lung TRM CD8+ T cells facilitates cell locomotion (motility) in vitro and in vivo, but is not required for trafficking of T cells to the lung. CD49a supports CD8+ TRM persistence within skin and regulates epidermal TRM dendritic extensions. TGF-β and IL-12 can induce CD49a expression on CD8+ T cells in vitro. CD49a expression is not required for the primary CD8+ T cell response, migration across the epidermal basement membrane, or TRM positioning in basal epidermis.","method":"Live imaging, intravital microscopy, genetic knockout (CD49a-deficient mice), flow cytometry, in vitro migration assay, cytokine induction assay","journal":"PNAS / Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — live imaging and intravital microscopy plus genetic knockout, two independent studies converging on CD49a-mediated motility and persistence","pmids":["32439709","32877667"],"is_preprint":false},{"year":2023,"finding":"RUNX2 and RUNX3 transcription factors are required for CD49a expression and cytotoxic transcriptional programs in human epidermal CD8+CD103+CD49a+ TRM cells. In vitro stimulation of circulating CD8+ memory T cells with IL-15 and TGF-β induced CD49a expression and cytotoxic profiles in a RUNX2- and RUNX3-dependent manner, establishing these TFs as writers of the CD49a+ TRM differentiation program.","method":"RUNX2/RUNX3 knockdown (siRNA/shRNA), in vitro differentiation with IL-15 and TGF-β, transcriptome sequencing, paired skin/blood clonal analysis, flow cytometry","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — specific transcription factor knockdown with functional readout, paired sequencing, and in vitro reconstitution of differentiation, multiple orthogonal methods","pmids":["37269830"],"is_preprint":false},{"year":2024,"finding":"Loss of ITGA1 (and ITGA2) activates EMT via enhanced secretion and autocrine activation of TGFβ1 and nuclear targeting of YAP1 in prostate epithelial cells. The transcription factor TEAD1 directly regulates ITGA1 and ITGA2 expression in prostate cancer cells, and TEAD1 loss phenocopies dual integrin loss in vitro and in vivo.","method":"Genomic deletion, CRISPR/shRNA knockdown, in vitro EMT assays, in vivo tumorigenesis, TGFβ1 measurement, YAP1 nuclear localization, genome-wide co-expression analysis, ChIP/regulatory analysis","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with mechanistic pathway identification, single lab","pmids":["38169150"],"is_preprint":false},{"year":2021,"finding":"VLA-1 (alpha1beta1/CD49a) adhesion to collagen IV is required for extended interaction times between activated MDSCs and effector T cells in the splenic red pulp, enabling effective T cell suppression. VLA-1-deficient A-MDSCs showed reduced interaction times with effector T cells on collagen IV (but not fibronectin) and reduced suppressive activity in vivo, without affecting MDSC motility or migration parameters.","method":"Itga1-/- knockout mice, intravital two-photon microscopy, in vitro and in vivo suppression assays, MDSC-T cell interaction timing, T cell proliferation and apoptosis assays","journal":"Frontiers in immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with intravital two-photon microscopy and functional suppression assay, multiple orthogonal methods","pmids":["33584706"],"is_preprint":false},{"year":2023,"finding":"Integrin alpha1beta1 (ITGA1) moderates TGFβ receptor II (TGFBR2) signaling in cartilage chondrocytes. Itga1-null mice develop earlier and more severe spontaneous knee osteoarthritis with increased baseline TGFBR2 activation and fibrosis. Cartilage-specific depletion of TGFBR2 in itga1-null mice attenuated OA progression, demonstrating a genetic epistasis relationship where ITGA1 normally dampens TGFBR2 signaling to protect against cartilage degeneration.","method":"Genetic knockout (itga1-/- mice), tamoxifen-induced cartilage-specific TGFBR2 depletion, histological OA scoring, pain behavior assays, TGFBR2 signaling pathway analysis","journal":"Osteoarthritis and cartilage open","confidence":"High","confidence_rationale":"Tier 2 / Strong — double-mutant genetic epistasis experiment with defined histological and behavioral readouts, rescues OA phenotype","pmids":["37649532"],"is_preprint":false},{"year":2025,"finding":"CD49a on NK cells mediates an exhausted/dysfunctional state in tumor-infiltrating NK cells. CD49a deficiency or antibody blockade slowed tumor growth and prolonged survival in multiple mouse tumor models, primarily through NK cell antitumor activity. Combination of anti-CD49a with anti-PD-L1 further enhanced antitumor efficacy.","method":"Genetic knockout (CD49a-/- and NK-specific CD49a-deficient mice), mAb blockade, multiple tumor models, survival analysis, NK cell functional assays","journal":"Cancer immunology research","confidence":"High","confidence_rationale":"Tier 2 / Strong — both genetic knockout and antibody blockade converge on the same tumor phenotype, confirmed in multiple tumor models","pmids":["39570767"],"is_preprint":false},{"year":2025,"finding":"Microglial CD49a (ITGA1) drives neuroinflammation in Parkinson's disease models. Microglial-specific Itga1 knockdown attenuates hyperreactivity, preserves dopaminergic neurons, and improves motor deficits. Mechanistically, ITGA1 knockdown in microglia reduces PGAM5 expression, which ameliorates mitochondrial dysfunction and suppresses NLRP3 inflammasome assembly. The disintegrin obtustatin specifically antagonizes microglial CD49a and reproduces these protective effects.","method":"Conditional Itga1 knockdown, transcriptomic profiling of isolated microglia, NLRP3 inflammasome assays, mitochondrial function assays, obtustatin pharmacological antagonism, PD mouse models","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockdown with transcriptomic pathway analysis and pharmacological confirmation, single lab","pmids":["41462565"],"is_preprint":false},{"year":2023,"finding":"ITGA1 (integrin alpha1) promotes hepatocellular carcinoma cell migration and invasion in vitro, and this is regulated transcriptionally: E2F1 directly activates ITGA1 transcription (shown by ChIP), and ITGA1 partially mediates d-ICD-induced suppression of migration; overexpression of ITGA1 partially rescues migration inhibited by d-ICD treatment.","method":"Wound healing assay, transwell invasion assay, Western blot, qRT-PCR, rescue experiments with ITGA1 overexpression","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus functional rescue experiments, single lab","pmids":["28264467"],"is_preprint":false},{"year":2025,"finding":"RBM15B promotes ITGA1 mRNA stability through m6A modification in glioblastoma cells. Downregulation of RBM15B reduces ITGA1 m6A modification levels and decreases ITGA1 mRNA stability. ITGA1 overexpression activates the PI3K-Akt signaling pathway to promote GBM cell proliferation, migration, and invasion.","method":"Methylated RNA immunoprecipitation (MeRIP), actinomycin D mRNA stability assay, Western blot, PI3K-Akt pathway analysis, in vivo xenograft","journal":"Discover oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MeRIP and mRNA stability assay directly demonstrate m6A-dependent regulation, single lab","pmids":["42020859"],"is_preprint":false},{"year":2025,"finding":"Thrombospondin 1 (THBS1) promotes accumulation of ITGA1 (and ITGA6) on the osteosarcoma cell membrane in the early phase of dedifferentiation, which increases phosphorylation of FAK, RasGRF1, and MLC2, promoting cytoskeletal remodeling and pulmonary metastasis.","method":"Sphere formation assay, mRNA-seq, Western blot for FAK/RasGRF1/MLC2 phosphorylation, membrane protein fractionation, in vivo metastasis model","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic signaling cascade identified by Western blot with defined upstream stimulus, single lab","pmids":["40083708"],"is_preprint":false},{"year":2025,"finding":"ITGA1 knockdown or pharmacological inhibition with obtustatin impairs proliferation, migration, and clonogenicity of retinoblastoma (Y79) cells. Transcriptome analysis and Western blot identified STAT3 as a key downstream mediator of ITGA1 signaling; STAT3 agonist ML115 partially rescued the inhibitory effects of ITGA1 suppression.","method":"Lentiviral ITGA1 knockdown, obtustatin inhibition, transcriptome analysis, Western blot, STAT3 rescue experiments, in vivo xenograft","journal":"Experimental eye research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockdown and pharmacological inhibition converge, pathway identified by transcriptomics and rescue, single lab","pmids":["40939856"],"is_preprint":false},{"year":2024,"finding":"ITGA1 promotes interstitial fibrosis in ADPKD: Pkd1nl/nl Itga1-/- double-knockout mice showed significantly reduced kidney volume, smaller cysts, reduced interstitial expansion, less collagen staining, and reduced myofibroblast marker expression compared to Pkd1nl/nl mice. Primary fibroblast cultures from Itga1-/- mice showed abrogated fibrogenic phenotype.","method":"Double-knockout mouse model, proteomics, kidney histology (Picrosirius red, α-SMA), primary fibroblast culture","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo double-knockout with in vitro fibroblast corroboration, preprint (not yet peer-reviewed)","pmids":[],"is_preprint":true},{"year":2017,"finding":"ITGA1 expression is specifically suppressed in the megakaryocyte lineage through progressive CpG methylation of its promoter during thrombopoietin-induced megakaryocyte differentiation. The ITGA1 promoter contains a serum response factor (SRF)-binding CArG box. Neither PELO nor ITGA2 (the neighboring genes in the ITGA1-PELO-ITGA2 locus) undergo similar methylation during this process.","method":"Sodium bisulfite sequencing, LUC reporter assay, 5-aza-2'-deoxycytidine demethylation, Trichostatin A treatment, qPCR time course during megakaryocyte differentiation","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1 / Strong — locus-specific methylation demonstrated by bisulfite sequencing, causality established by pharmacological demethylation and reporter assays, multiple orthogonal methods in one study","pmids":["17669516"],"is_preprint":false}],"current_model":"ITGA1/CD49a encodes the alpha-1 subunit of the heterodimeric integrin VLA-1 (alpha1beta1), which functions as a major collagen (types I–IV) and laminin receptor requiring divalent cations (Mg2+/Mn2+, inhibited by Ca2+); its expression is transcriptionally controlled by SRF via a CArG box and suppressed in megakaryocytes by promoter CpG methylation, induced on T cells and monocytes by activation signals (with RUNX2/RUNX3 driving CD49a expression in cytotoxic TRM cells), and once expressed it mediates tissue retention of memory T and NK cells via collagen-dependent adhesion, modulates T cell and MDSC suppressive interactions through extended collagen IV contact, restrains TGFβ receptor II signaling in chondrocytes to protect against osteoarthritis, and in tumors promotes cancer cell migration/invasion through downstream FAK, STAT3, and PI3K-Akt pathways while also driving NK cell exhaustion in the tumor microenvironment."},"narrative":{"mechanistic_narrative":"ITGA1 (CD49a) encodes the alpha-1 subunit of the integrin VLA-1, which pairs in a 1:1 acid-labile, heavily glycosylated heterodimer with a beta-1 subunit on activated T cells [PMID:2415516] and functions as a divalent-cation-dependent receptor for interstitial and basement-membrane collagens (types I–IV), C1q, and laminin through a non-RGD binding mechanism [PMID:2229189, PMID:1807406]. Ligand engagement requires Mg2+ or Mn2+ and is inhibited by Ca2+, and adhesion can be activated through the beta-1 subunit or stimulated by PKC [PMID:7516898, PMID:10457223]; ligand specificity is further tuned in a cell-type-specific manner, with VLA-1 serving as a principal laminin and/or collagen receptor depending on context [PMID:7898055]. Beyond adhesion, VLA-1 transduces intracellular signals upon clustering [PMID:8025956]. Functionally, VLA-1-mediated collagen attachment anchors memory and tissue-resident T cells in nonlymphoid tissues, sustaining their persistence, motility, and recall responses while being dispensable for trafficking into those tissues [PMID:14975239, PMID:20200271, PMID:37269830], and it likewise maintains gut intraepithelial lymphocytes and supports collagen-dependent T cell proliferation [PMID:10805967]. The same collagen-IV-dependent contact extends MDSC–T cell interactions to enable immune suppression [PMID:33584706] and drives NK cell dysfunction, with CD49a blockade restoring cytotoxicity in the tumor microenvironment [PMID:30756436, PMID:39570767]. ITGA1 also restrains TGFβ-receptor-II signaling in chondrocytes to protect against osteoarthritis [PMID:37649532], promotes fibrosis in kidney disease [PMID:12368200], and drives microglial neuroinflammation via a PGAM5/NLRP3 axis [PMID:41462565]. In multiple cancers ITGA1 promotes migration and invasion through downstream FAK, STAT3, and PI3K-Akt signaling [PMID:40083708, PMID:40939856, PMID:42020859]. Its expression is controlled both transcriptionally—by SRF at a promoter CArG box, by E2F1 and TEAD1, and by RUNX2/RUNX3 in cytotoxic TRM differentiation—and epigenetically by promoter CpG methylation that silences it in the megakaryocyte lineage [PMID:17669516, PMID:37269830, PMID:38169150].","teleology":[{"year":1985,"claim":"Established the molecular identity of VLA-1 as a defined integrin heterodimer, answering what the CD49a antigen physically is.","evidence":"Cross-linking, immunoprecipitation, SDS-PAGE and peptide mapping on activated T cells","pmids":["2415516"],"confidence":"High","gaps":["Did not define the ligand specificity of the complex","Beta subunit identity not yet placed in the integrin family"]},{"year":1991,"claim":"Defined the ligand repertoire and binding mode of VLA-1, showing it is a cation-dependent, non-RGD collagen/laminin receptor.","evidence":"Affinity-purified VLA-1 reconstituted into liposomes, tested against multiple ECM substrates with RGD peptide and cation manipulation","pmids":["2229189","1807406"],"confidence":"High","gaps":["Did not map the collagen-binding site on the alpha-1 subunit","Conformational basis of activation not addressed"]},{"year":1994,"claim":"Demonstrated that VLA-1 adhesion is regulated by divalent cation switching and can transduce outside-in signals, not merely mediate static attachment.","evidence":"Cell adhesion assays with Mg2+/Mn2+/Ca2+ manipulation, activating anti-beta1 antibody, and antibody-induced IL-2R expression","pmids":["7516898","8025956"],"confidence":"Medium","gaps":["Downstream signaling intermediates not identified","Mechanism of cation-dependent affinity change not resolved structurally"]},{"year":1995,"claim":"Showed VLA-1 expression is dynamically regulated by activation and quiescence states and by inflammatory cytokines, framing it as an inducible context-dependent receptor.","evidence":"Flow cytometry, immunoprecipitation and Northern blot on T cells, fibroblasts, and monocytes under defined stimulation/redox conditions","pmids":["3106495","3292271","7589148"],"confidence":"Medium","gaps":["Transcription factors driving induction not identified at this stage","Cell-type heterogeneity of regulation not mechanistically explained"]},{"year":2000,"claim":"Genetic loss-of-function established VLA-1 as required in vivo for gut intraepithelial lymphocyte maintenance and collagen-dependent T cell proliferation.","evidence":"VLA-1 null mice with lymphocyte counting and adhesion/proliferation assays","pmids":["10805967"],"confidence":"High","gaps":["Whether retention vs. proliferation drives the IEL deficit unresolved","Signaling pathway behind collagen-dependent proliferation unknown"]},{"year":2010,"claim":"Defined VLA-1 as a tissue-retention factor for memory CD8 and CD4 T cells, distinguishing tissue anchoring from trafficking.","evidence":"Antibody blockade and alpha1-/- mice in influenza challenge models with tissue-compartment flow cytometry and recall assays","pmids":["14975239","20200271"],"confidence":"High","gaps":["Molecular link between collagen adhesion and anti-apoptotic survival not detailed","Contribution of signaling vs. physical anchoring not separated"]},{"year":2007,"claim":"Revealed dual transcriptional/epigenetic control of ITGA1, identifying an SRF CArG box and lineage-specific CpG methylation silencing in megakaryocytes.","evidence":"Bisulfite sequencing, promoter-LUC reporters, 5-aza-2'-deoxycytidine demethylation and TPO differentiation time course","pmids":["17669516"],"confidence":"High","gaps":["The de novo methyltransferase responsible not identified","How SRF activity intersects with methylation status unresolved"]},{"year":2020,"claim":"Distinguished CD49a's role in TRM locomotion and persistence from its dispensability for trafficking, and identified TGF-β/IL-12/IL-15 plus RUNX2/RUNX3 as inducers of the CD49a+ cytotoxic TRM program.","evidence":"Intravital imaging and CD49a-deficient mice; RUNX2/RUNX3 knockdown with in vitro IL-15/TGF-β differentiation and transcriptomics","pmids":["32439709","32877667","37269830"],"confidence":"High","gaps":["Direct RUNX binding at the ITGA1 locus not mapped","How CD49a mechanically drives dendritic motility unresolved"]},{"year":2023,"claim":"Genetic epistasis established that ITGA1 normally restrains TGFBR2 signaling, defining a protective role against osteoarthritis and fibrosis.","evidence":"itga1-/- mice with cartilage-specific TGFBR2 depletion, histological OA scoring and pain assays; antibody neutralization in glomerulonephritis","pmids":["37649532","12368200"],"confidence":"High","gaps":["Biochemical mechanism by which ITGA1 dampens TGFBR2 not defined","Whether direct receptor cross-talk or indirect ECM remodeling mediates restraint unknown"]},{"year":2021,"claim":"Showed VLA-1/collagen-IV contact extends suppressive immune-cell interactions, implicating it in MDSC-mediated T cell suppression.","evidence":"Itga1-/- mice with intravital two-photon microscopy and in vivo suppression assays","pmids":["33584706"],"confidence":"High","gaps":["Signaling consequence of prolonged contact in MDSCs not defined","Generalizability beyond splenic red pulp unaddressed"]},{"year":2025,"claim":"Connected CD49a to NK cell exhaustion and microglial neuroinflammation, positioning it as a therapeutic target in tumors and Parkinson's disease.","evidence":"CD49a knockout and antibody blockade across tumor models with anti-PD-L1 combination; 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210,000 alpha-1 subunit in acid-labile association with an Mr 130,000 beta subunit, forming a 1:1 stoichiometric heterodimer on activated T cells. The alpha-1 and beta subunits contain substantial sialic acid and N-linked carbohydrate, and are highly non-homologous to each other by peptide mapping.\",\n      \"method\": \"Cross-linking experiments, immunoprecipitation, SDS-PAGE, neuraminidase/endoglycosidase F digestion, one-dimensional peptide mapping\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical reconstitution and characterization with multiple orthogonal methods in a focused study\",\n      \"pmids\": [\"2415516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1990,\n      \"finding\": \"Purified VLA-1 integrin from human smooth muscle (195 kD alpha + 130 kD beta subunits) binds type I, II, III, and IV collagens, C1q, and laminin in a Ca2+/Mg2+-dependent manner via liposome adhesion assays. It does not bind gelatin, fibronectin, or thrombospondin.\",\n      \"method\": \"Affinity chromatography on collagen-Sepharose, liposome adhesion assay, quantitative immunoblotting\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — purified protein reconstituted into liposomes and tested against multiple substrates with divalent cation dependence established\",\n      \"pmids\": [\"2229189\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"Purified VLA-1 from human smooth muscle interacts with interstitial collagens (types I, II, III) and basement membrane proteins (type IV collagen and laminin) via a Ca2+/Mg2+-dependent mechanism in liposome assays; does not interact with fibronectin, thrombospondin, or albumin. The RGD peptide does not inhibit binding, indicating a non-RGD binding mechanism. Denaturation of type I collagen reduces binding 5–7-fold.\",\n      \"method\": \"Liposome binding assay with purified VLA-1 integrin, inhibition experiments with RGD peptide and cation chelation\",\n      \"journal\": \"Biokhimiia (Moscow, Russia)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — purified protein in liposome reconstitution assay, replicated substrate specificity findings from concurrent work\",\n      \"pmids\": [\"1807406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1987,\n      \"finding\": \"VLA-1 expression on T cells is downregulated by mitogenic stimulation (PHA, ConA) in a reversible manner, whereas VLA-2 is not similarly suppressed. Repetitive restimulation with alloantigen or anti-CD3 increases the VLA-2:VLA-1 ratio. These changes are intrinsic to homogeneous T cell lines, not due to subpopulation shifts, indicating cell-cycle/activation-state-dependent regulation of VLA-1 expression.\",\n      \"method\": \"Flow cytometry, immunoprecipitation of T cell lines under defined stimulation conditions\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean cell-line experiments with defined stimuli, two orthogonal detection methods, single lab\",\n      \"pmids\": [\"3106495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1988,\n      \"finding\": \"Cell quiescence induced by low serum (0.5%) causes a 10–28-fold increase in VLA-1 expression on normal human fibroblasts with a corresponding decrease in VLA-2 and VLA-3. These changes are reversible upon re-stimulation with serum and persist after proliferation has stopped, indicating that VLA-1 upregulation is linked to quiescence rather than cell-cycle transitions per se.\",\n      \"method\": \"Flow cytometry, immunoprecipitation, quantitative comparison under defined serum conditions\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative flow cytometry and immunoprecipitation, two methods, single lab\",\n      \"pmids\": [\"3292271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"VLA-1-mediated adhesion of NB100 neuroblastoma cells to collagen type I is supported by Mg2+ (mM) or Mn2+ (µM) but not Ca2+ alone; Ca2+ inhibits Mg2+-supported adhesion. VLA-1 can be directly activated by the stimulatory anti-β1 monoclonal antibody TS2/16 to promote collagen adhesion.\",\n      \"method\": \"Cell adhesion assay with divalent cation manipulation, blocking antibody experiments, monoclonal antibody activation\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional assay with pharmacological and antibody interventions, single lab, multiple conditions tested\",\n      \"pmids\": [\"7516898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"VLA-1 (CD49a) on T cells functions as a specific collagen IV receptor: antibody blockade of CD49a (mAb 1B3.1) inhibited adhesion to collagen IV but not fibronectin, and Mg2+ supported VLA-1-mediated spreading on collagen IV. Cross-linking of VLA-1 with plastic-bound antibody selectively induced IL-2R expression on γδ T cell clones, demonstrating VLA-1 can transduce intracellular signals.\",\n      \"method\": \"Cell adhesion assay, antibody blocking, cation manipulation, IL-2R expression by flow cytometry\",\n      \"journal\": \"Cellular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional adhesion and signaling assays with specific blocking mAb, single lab\",\n      \"pmids\": [\"8025956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"In glomerular epithelial cells (GEC), VLA-1 and VLA-2 cooperate for adhesion to laminin, while only VLA-2 is used for collagen adhesion. In mesangial cells, VLA-1 is the primary laminin receptor and both VLA-1 and VLA-2 support collagen adhesion. This demonstrates cell-type-specific modulation of VLA-1 ligand binding specificity.\",\n      \"method\": \"Monoclonal antibody blocking of cell adhesion to extracellular matrix proteins, ELISA, immunocytochemistry\",\n      \"journal\": \"Laboratory investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional blocking antibody adhesion assays on two distinct cell types, single lab\",\n      \"pmids\": [\"7898055\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Integrin alpha1beta1 (VLA-1) is the primary collagen receptor on human intestinal intraepithelial lymphocytes (IELs): antibody blockade of alpha1 (CD49a) and beta1 subunits inhibited IEL adhesion to collagen type I by ~82% and to type IV by ~94%. Adhesion was upregulated by PKC stimulation (phorbol ester) and was dependent on divalent cations (Mn2+/Mg2+ supportive, Ca2+ inhibitory), consistent with canonical integrin activation.\",\n      \"method\": \"51Cr-labeled cell adhesion assay, antibody blocking, pharmacological stimulation (PKC activators/inhibitors), divalent cation manipulation\",\n      \"journal\": \"Immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — quantitative radioactive adhesion assay with specific antibody blockade and multiple mechanistic interventions, findings consistent with parallel studies\",\n      \"pmids\": [\"10457223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"VLA-1 null mice have a ~50% reduction in gut intraepithelial lymphocytes (IELs) with normal peripheral blood and lymphoid organ lymphocyte distribution and unchanged γδ:αβ IEL ratios. IL-2-stimulated splenocytes from VLA-1 null mice show deficient adhesion to fibrillar and basement membrane collagen and reduced proliferation on collagen substratum, demonstrating that VLA-1 is required for IEL maintenance in the gut and for collagen-dependent T cell proliferation.\",\n      \"method\": \"Genetic knockout mouse (VLA-1 null), cell counting, adhesion assays, proliferation assays\",\n      \"journal\": \"Cellular immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout phenotype with specific cellular and functional readouts, in vivo and in vitro\",\n      \"pmids\": [\"10805967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"VLA-1 (alpha1beta1 integrin) is required for retention of influenza-specific CD8 memory T cells in the lung and nonlymphoid tissues. Antibody blockade or genetic deficiency of VLA-1 decreased virus-specific CTL in lung and other nonlymphoid tissues while increasing them in the spleen, and impaired secondary heterosubtypic immunity, demonstrating that VLA-1 mediates T cell retention in tissues via ECM attachment.\",\n      \"method\": \"Antibody blockade, genetic knockout mice, flow cytometry, challenge infection model, tissue distribution analysis\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — both antibody blockade and genetic deficiency converge on the same phenotype, with in vivo functional consequence\",\n      \"pmids\": [\"14975239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The ITGA1 gene locus is regulated by DNA CpG methylation: the ITGA1 promoter is fully methylated at 19 CpG sites in megakaryocytic (MK) cells that do not express alpha1beta1, and completely demethylated in expressing cells. In vitro methylation of ITGA1 suppresses transcription. Treatment with the DNA demethylating agent 5-aza-2'-deoxycytidine (but not the HDAC inhibitor Trichostatin A) induces de novo ITGA1 expression in MK cells. Progressive CpG methylation of ITGA1 occurs during thrombopoietin-induced megakaryocyte differentiation. The ITGA1 promoter also contains a CArG box bound by serum response factor (SRF).\",\n      \"method\": \"Sodium bisulfite genomic sequencing, promoter-LUC reporter assays, 5-aza-2'-deoxycytidine treatment, qPCR, Northern blot, transcription factor binding analysis\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (bisulfite sequencing, reporter assay, pharmacological demethylation, differentiation time course) in a single rigorous study\",\n      \"pmids\": [\"17669516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VLA-1 antibody blockade in a rat model of crescentic glomerulonephritis reduced glomerular and tubulointerstitial scarring, decreased type IV collagen and ED(A) fibronectin deposition, and increased matrix metalloproteinase-9 expression in glomeruli. This demonstrates that VLA-1 mediates renal fibrosis, and that its neutralization promotes matrix degradation via MMP-9 upregulation.\",\n      \"method\": \"Monoclonal antibody treatment in vivo (rat model), histology, immunohistochemistry, biochemical markers\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo antibody neutralization with defined structural and biochemical readouts, single lab\",\n      \"pmids\": [\"12368200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VLA-1 (alpha1beta1) is required for the accumulation of CD4+ tissue memory T cells in the airways after influenza infection. Fewer memory/effector CD4+ T cells were recovered from airways of alpha1-/- mice but lymphoid tissues were unaffected. Airway CD49a+CD4+ cells expressed reduced apoptosis markers and provided rapid IFN-γ responses upon secondary challenge.\",\n      \"method\": \"Genetic knockout mice (alpha1-/-), flow cytometry, intracellular cytokine staining, apoptosis markers, secondary challenge infection model\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout phenotype with specific tissue-compartment readout and functional secondary challenge, consistent with parallel CD8 T cell findings\",\n      \"pmids\": [\"20200271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"LPS and IFN-γ rapidly induce de novo expression of alpha1/beta1 (VLA-1) integrin on monocytes, detectable on the membrane within 12 hours, with induction of alpha1 mRNA. This induction is dependent on the cellular redox state (inhibited by antioxidants). Monocyte-deactivating cytokines (IL-4, IL-10) only minimally inhibit this upregulation.\",\n      \"method\": \"Flow cytometry, Northern blot, pharmacological inhibition with antioxidants and cytokines\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Northern blot and flow cytometry, specific induction conditions tested, single lab\",\n      \"pmids\": [\"7589148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VLA-1 on MS patient-derived, myelin antigen-reactive T cell lines mediates adhesion to collagen IV (the major collagenous constituent of vascular basement membranes) and active transmigration through collagen IV gels toward TNF-α; both processes were inhibited almost completely by anti-VLA-1 mAb. Ionizing radiation abrogated VLA-1-mediated collagen IV adhesion, suggesting radiation-induced integrin clustering impairs VLA-1 function.\",\n      \"method\": \"Cell adhesion assay, transwell transmigration assay, antibody blocking, irradiation experiments, immunofluorescence of integrin clustering\",\n      \"journal\": \"Journal of clinical immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional assays with specific antibody blockade, single lab, two orthogonal assays\",\n      \"pmids\": [\"12078857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ITGA1 (integrin alpha1) is required for collagen-induced tumorigenic potential in pancreatic ductal adenocarcinoma (PDAC) cells. ITGA1 depletion impairs collagen/ITGA1 signaling that supports survival of ALDH1+ stem-like cancer cells and cooperates with TGFβ to drive gemcitabine resistance. ITGA1 is also required for TGFβ/collagen-induced EMT and metastasis.\",\n      \"method\": \"siRNA/shRNA knockdown of ITGA1, colony/invasion assays, stem cell marker analysis (ALDH1), drug resistance assays, metastasis assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with multiple defined phenotypic readouts, single lab\",\n      \"pmids\": [\"28855593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"E2F1 transcription factor directly upregulates ITGA1 expression in hepatocellular carcinoma cells, as demonstrated by dual luciferase reporter assay and chromatin immunoprecipitation. d-ICD inhibits E2F1 expression and thereby suppresses ITGA1-mediated HCC cell migration and invasion.\",\n      \"method\": \"Dual luciferase reporter assay, chromatin immunoprecipitation (ChIP), wound healing assay, transwell invasion assay, Western blot, qRT-PCR\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct transcription factor binding demonstrated by ChIP and luciferase reporter, two orthogonal methods, single lab\",\n      \"pmids\": [\"28264467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CD49a (ITGA1) on human decidual NK cells suppresses cytotoxicity: CD49a neutralizing antibody upregulated perforin, granzyme B, and IFN-γ expression, increased killing activity (51Cr release assay), and downregulated dNK cell migration and adhesion. A newly identified lncRNA (lnc-49a) was shown to positively regulate CD49a expression in primary human NK cells.\",\n      \"method\": \"CD49a neutralizing antibody, flow cytometry, 51Cr release cytotoxicity assay, lncRNA microarray, primary human NK cells\",\n      \"journal\": \"American journal of reproductive immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional neutralization with specific cytotoxicity assay and mechanistic lncRNA regulator identification, single lab\",\n      \"pmids\": [\"30756436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CD49a (integrin alpha1) on lung TRM CD8+ T cells facilitates cell locomotion (motility) in vitro and in vivo, but is not required for trafficking of T cells to the lung. CD49a supports CD8+ TRM persistence within skin and regulates epidermal TRM dendritic extensions. TGF-β and IL-12 can induce CD49a expression on CD8+ T cells in vitro. CD49a expression is not required for the primary CD8+ T cell response, migration across the epidermal basement membrane, or TRM positioning in basal epidermis.\",\n      \"method\": \"Live imaging, intravital microscopy, genetic knockout (CD49a-deficient mice), flow cytometry, in vitro migration assay, cytokine induction assay\",\n      \"journal\": \"PNAS / Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live imaging and intravital microscopy plus genetic knockout, two independent studies converging on CD49a-mediated motility and persistence\",\n      \"pmids\": [\"32439709\", \"32877667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RUNX2 and RUNX3 transcription factors are required for CD49a expression and cytotoxic transcriptional programs in human epidermal CD8+CD103+CD49a+ TRM cells. In vitro stimulation of circulating CD8+ memory T cells with IL-15 and TGF-β induced CD49a expression and cytotoxic profiles in a RUNX2- and RUNX3-dependent manner, establishing these TFs as writers of the CD49a+ TRM differentiation program.\",\n      \"method\": \"RUNX2/RUNX3 knockdown (siRNA/shRNA), in vitro differentiation with IL-15 and TGF-β, transcriptome sequencing, paired skin/blood clonal analysis, flow cytometry\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — specific transcription factor knockdown with functional readout, paired sequencing, and in vitro reconstitution of differentiation, multiple orthogonal methods\",\n      \"pmids\": [\"37269830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of ITGA1 (and ITGA2) activates EMT via enhanced secretion and autocrine activation of TGFβ1 and nuclear targeting of YAP1 in prostate epithelial cells. The transcription factor TEAD1 directly regulates ITGA1 and ITGA2 expression in prostate cancer cells, and TEAD1 loss phenocopies dual integrin loss in vitro and in vivo.\",\n      \"method\": \"Genomic deletion, CRISPR/shRNA knockdown, in vitro EMT assays, in vivo tumorigenesis, TGFβ1 measurement, YAP1 nuclear localization, genome-wide co-expression analysis, ChIP/regulatory analysis\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with mechanistic pathway identification, single lab\",\n      \"pmids\": [\"38169150\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VLA-1 (alpha1beta1/CD49a) adhesion to collagen IV is required for extended interaction times between activated MDSCs and effector T cells in the splenic red pulp, enabling effective T cell suppression. VLA-1-deficient A-MDSCs showed reduced interaction times with effector T cells on collagen IV (but not fibronectin) and reduced suppressive activity in vivo, without affecting MDSC motility or migration parameters.\",\n      \"method\": \"Itga1-/- knockout mice, intravital two-photon microscopy, in vitro and in vivo suppression assays, MDSC-T cell interaction timing, T cell proliferation and apoptosis assays\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with intravital two-photon microscopy and functional suppression assay, multiple orthogonal methods\",\n      \"pmids\": [\"33584706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Integrin alpha1beta1 (ITGA1) moderates TGFβ receptor II (TGFBR2) signaling in cartilage chondrocytes. Itga1-null mice develop earlier and more severe spontaneous knee osteoarthritis with increased baseline TGFBR2 activation and fibrosis. Cartilage-specific depletion of TGFBR2 in itga1-null mice attenuated OA progression, demonstrating a genetic epistasis relationship where ITGA1 normally dampens TGFBR2 signaling to protect against cartilage degeneration.\",\n      \"method\": \"Genetic knockout (itga1-/- mice), tamoxifen-induced cartilage-specific TGFBR2 depletion, histological OA scoring, pain behavior assays, TGFBR2 signaling pathway analysis\",\n      \"journal\": \"Osteoarthritis and cartilage open\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — double-mutant genetic epistasis experiment with defined histological and behavioral readouts, rescues OA phenotype\",\n      \"pmids\": [\"37649532\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CD49a on NK cells mediates an exhausted/dysfunctional state in tumor-infiltrating NK cells. CD49a deficiency or antibody blockade slowed tumor growth and prolonged survival in multiple mouse tumor models, primarily through NK cell antitumor activity. Combination of anti-CD49a with anti-PD-L1 further enhanced antitumor efficacy.\",\n      \"method\": \"Genetic knockout (CD49a-/- and NK-specific CD49a-deficient mice), mAb blockade, multiple tumor models, survival analysis, NK cell functional assays\",\n      \"journal\": \"Cancer immunology research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — both genetic knockout and antibody blockade converge on the same tumor phenotype, confirmed in multiple tumor models\",\n      \"pmids\": [\"39570767\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Microglial CD49a (ITGA1) drives neuroinflammation in Parkinson's disease models. Microglial-specific Itga1 knockdown attenuates hyperreactivity, preserves dopaminergic neurons, and improves motor deficits. Mechanistically, ITGA1 knockdown in microglia reduces PGAM5 expression, which ameliorates mitochondrial dysfunction and suppresses NLRP3 inflammasome assembly. The disintegrin obtustatin specifically antagonizes microglial CD49a and reproduces these protective effects.\",\n      \"method\": \"Conditional Itga1 knockdown, transcriptomic profiling of isolated microglia, NLRP3 inflammasome assays, mitochondrial function assays, obtustatin pharmacological antagonism, PD mouse models\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockdown with transcriptomic pathway analysis and pharmacological confirmation, single lab\",\n      \"pmids\": [\"41462565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ITGA1 (integrin alpha1) promotes hepatocellular carcinoma cell migration and invasion in vitro, and this is regulated transcriptionally: E2F1 directly activates ITGA1 transcription (shown by ChIP), and ITGA1 partially mediates d-ICD-induced suppression of migration; overexpression of ITGA1 partially rescues migration inhibited by d-ICD treatment.\",\n      \"method\": \"Wound healing assay, transwell invasion assay, Western blot, qRT-PCR, rescue experiments with ITGA1 overexpression\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus functional rescue experiments, single lab\",\n      \"pmids\": [\"28264467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RBM15B promotes ITGA1 mRNA stability through m6A modification in glioblastoma cells. Downregulation of RBM15B reduces ITGA1 m6A modification levels and decreases ITGA1 mRNA stability. ITGA1 overexpression activates the PI3K-Akt signaling pathway to promote GBM cell proliferation, migration, and invasion.\",\n      \"method\": \"Methylated RNA immunoprecipitation (MeRIP), actinomycin D mRNA stability assay, Western blot, PI3K-Akt pathway analysis, in vivo xenograft\",\n      \"journal\": \"Discover oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MeRIP and mRNA stability assay directly demonstrate m6A-dependent regulation, single lab\",\n      \"pmids\": [\"42020859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Thrombospondin 1 (THBS1) promotes accumulation of ITGA1 (and ITGA6) on the osteosarcoma cell membrane in the early phase of dedifferentiation, which increases phosphorylation of FAK, RasGRF1, and MLC2, promoting cytoskeletal remodeling and pulmonary metastasis.\",\n      \"method\": \"Sphere formation assay, mRNA-seq, Western blot for FAK/RasGRF1/MLC2 phosphorylation, membrane protein fractionation, in vivo metastasis model\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic signaling cascade identified by Western blot with defined upstream stimulus, single lab\",\n      \"pmids\": [\"40083708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ITGA1 knockdown or pharmacological inhibition with obtustatin impairs proliferation, migration, and clonogenicity of retinoblastoma (Y79) cells. Transcriptome analysis and Western blot identified STAT3 as a key downstream mediator of ITGA1 signaling; STAT3 agonist ML115 partially rescued the inhibitory effects of ITGA1 suppression.\",\n      \"method\": \"Lentiviral ITGA1 knockdown, obtustatin inhibition, transcriptome analysis, Western blot, STAT3 rescue experiments, in vivo xenograft\",\n      \"journal\": \"Experimental eye research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockdown and pharmacological inhibition converge, pathway identified by transcriptomics and rescue, single lab\",\n      \"pmids\": [\"40939856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ITGA1 promotes interstitial fibrosis in ADPKD: Pkd1nl/nl Itga1-/- double-knockout mice showed significantly reduced kidney volume, smaller cysts, reduced interstitial expansion, less collagen staining, and reduced myofibroblast marker expression compared to Pkd1nl/nl mice. Primary fibroblast cultures from Itga1-/- mice showed abrogated fibrogenic phenotype.\",\n      \"method\": \"Double-knockout mouse model, proteomics, kidney histology (Picrosirius red, α-SMA), primary fibroblast culture\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo double-knockout with in vitro fibroblast corroboration, preprint (not yet peer-reviewed)\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ITGA1 expression is specifically suppressed in the megakaryocyte lineage through progressive CpG methylation of its promoter during thrombopoietin-induced megakaryocyte differentiation. The ITGA1 promoter contains a serum response factor (SRF)-binding CArG box. Neither PELO nor ITGA2 (the neighboring genes in the ITGA1-PELO-ITGA2 locus) undergo similar methylation during this process.\",\n      \"method\": \"Sodium bisulfite sequencing, LUC reporter assay, 5-aza-2'-deoxycytidine demethylation, Trichostatin A treatment, qPCR time course during megakaryocyte differentiation\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — locus-specific methylation demonstrated by bisulfite sequencing, causality established by pharmacological demethylation and reporter assays, multiple orthogonal methods in one study\",\n      \"pmids\": [\"17669516\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ITGA1/CD49a encodes the alpha-1 subunit of the heterodimeric integrin VLA-1 (alpha1beta1), which functions as a major collagen (types I–IV) and laminin receptor requiring divalent cations (Mg2+/Mn2+, inhibited by Ca2+); its expression is transcriptionally controlled by SRF via a CArG box and suppressed in megakaryocytes by promoter CpG methylation, induced on T cells and monocytes by activation signals (with RUNX2/RUNX3 driving CD49a expression in cytotoxic TRM cells), and once expressed it mediates tissue retention of memory T and NK cells via collagen-dependent adhesion, modulates T cell and MDSC suppressive interactions through extended collagen IV contact, restrains TGFβ receptor II signaling in chondrocytes to protect against osteoarthritis, and in tumors promotes cancer cell migration/invasion through downstream FAK, STAT3, and PI3K-Akt pathways while also driving NK cell exhaustion in the tumor microenvironment.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ITGA1 (CD49a) encodes the alpha-1 subunit of the integrin VLA-1, which pairs in a 1:1 acid-labile, heavily glycosylated heterodimer with a beta-1 subunit on activated T cells [#0] and functions as a divalent-cation-dependent receptor for interstitial and basement-membrane collagens (types I\\u2013IV), C1q, and laminin through a non-RGD binding mechanism [#1, #2]. Ligand engagement requires Mg2+ or Mn2+ and is inhibited by Ca2+, and adhesion can be activated through the beta-1 subunit or stimulated by PKC [#5, #8]; ligand specificity is further tuned in a cell-type-specific manner, with VLA-1 serving as a principal laminin and/or collagen receptor depending on context [#7]. Beyond adhesion, VLA-1 transduces intracellular signals upon clustering [#6]. Functionally, VLA-1-mediated collagen attachment anchors memory and tissue-resident T cells in nonlymphoid tissues, sustaining their persistence, motility, and recall responses while being dispensable for trafficking into those tissues [#10, #13, #20], and it likewise maintains gut intraepithelial lymphocytes and supports collagen-dependent T cell proliferation [#9]. The same collagen-IV-dependent contact extends MDSC\\u2013T cell interactions to enable immune suppression [#22] and drives NK cell dysfunction, with CD49a blockade restoring cytotoxicity in the tumor microenvironment [#18, #24]. ITGA1 also restrains TGF\\u03b2-receptor-II signaling in chondrocytes to protect against osteoarthritis [#23], promotes fibrosis in kidney disease [#12], and drives microglial neuroinflammation via a PGAM5/NLRP3 axis [#25]. In multiple cancers ITGA1 promotes migration and invasion through downstream FAK, STAT3, and PI3K-Akt signaling [#28, #29, #27]. Its expression is controlled both transcriptionally\\u2014by SRF at a promoter CArG box, by E2F1 and TEAD1, and by RUNX2/RUNX3 in cytotoxic TRM differentiation\\u2014and epigenetically by promoter CpG methylation that silences it in the megakaryocyte lineage [#11, #20, #21, #31].\",\n  \"teleology\": [\n    {\n      \"year\": 1985,\n      \"claim\": \"Established the molecular identity of VLA-1 as a defined integrin heterodimer, answering what the CD49a antigen physically is.\",\n      \"evidence\": \"Cross-linking, immunoprecipitation, SDS-PAGE and peptide mapping on activated T cells\",\n      \"pmids\": [\"2415516\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the ligand specificity of the complex\", \"Beta subunit identity not yet placed in the integrin family\"]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"Defined the ligand repertoire and binding mode of VLA-1, showing it is a cation-dependent, non-RGD collagen/laminin receptor.\",\n      \"evidence\": \"Affinity-purified VLA-1 reconstituted into liposomes, tested against multiple ECM substrates with RGD peptide and cation manipulation\",\n      \"pmids\": [\"2229189\", \"1807406\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the collagen-binding site on the alpha-1 subunit\", \"Conformational basis of activation not addressed\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Demonstrated that VLA-1 adhesion is regulated by divalent cation switching and can transduce outside-in signals, not merely mediate static attachment.\",\n      \"evidence\": \"Cell adhesion assays with Mg2+/Mn2+/Ca2+ manipulation, activating anti-beta1 antibody, and antibody-induced IL-2R expression\",\n      \"pmids\": [\"7516898\", \"8025956\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream signaling intermediates not identified\", \"Mechanism of cation-dependent affinity change not resolved structurally\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Showed VLA-1 expression is dynamically regulated by activation and quiescence states and by inflammatory cytokines, framing it as an inducible context-dependent receptor.\",\n      \"evidence\": \"Flow cytometry, immunoprecipitation and Northern blot on T cells, fibroblasts, and monocytes under defined stimulation/redox conditions\",\n      \"pmids\": [\"3106495\", \"3292271\", \"7589148\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factors driving induction not identified at this stage\", \"Cell-type heterogeneity of regulation not mechanistically explained\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Genetic loss-of-function established VLA-1 as required in vivo for gut intraepithelial lymphocyte maintenance and collagen-dependent T cell proliferation.\",\n      \"evidence\": \"VLA-1 null mice with lymphocyte counting and adhesion/proliferation assays\",\n      \"pmids\": [\"10805967\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether retention vs. proliferation drives the IEL deficit unresolved\", \"Signaling pathway behind collagen-dependent proliferation unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined VLA-1 as a tissue-retention factor for memory CD8 and CD4 T cells, distinguishing tissue anchoring from trafficking.\",\n      \"evidence\": \"Antibody blockade and alpha1-/- mice in influenza challenge models with tissue-compartment flow cytometry and recall assays\",\n      \"pmids\": [\"14975239\", \"20200271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link between collagen adhesion and anti-apoptotic survival not detailed\", \"Contribution of signaling vs. physical anchoring not separated\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Revealed dual transcriptional/epigenetic control of ITGA1, identifying an SRF CArG box and lineage-specific CpG methylation silencing in megakaryocytes.\",\n      \"evidence\": \"Bisulfite sequencing, promoter-LUC reporters, 5-aza-2'-deoxycytidine demethylation and TPO differentiation time course\",\n      \"pmids\": [\"17669516\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The de novo methyltransferase responsible not identified\", \"How SRF activity intersects with methylation status unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Distinguished CD49a's role in TRM locomotion and persistence from its dispensability for trafficking, and identified TGF-\\u03b2/IL-12/IL-15 plus RUNX2/RUNX3 as inducers of the CD49a+ cytotoxic TRM program.\",\n      \"evidence\": \"Intravital imaging and CD49a-deficient mice; RUNX2/RUNX3 knockdown with in vitro IL-15/TGF-\\u03b2 differentiation and transcriptomics\",\n      \"pmids\": [\"32439709\", \"32877667\", \"37269830\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct RUNX binding at the ITGA1 locus not mapped\", \"How CD49a mechanically drives dendritic motility unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Genetic epistasis established that ITGA1 normally restrains TGFBR2 signaling, defining a protective role against osteoarthritis and fibrosis.\",\n      \"evidence\": \"itga1-/- mice with cartilage-specific TGFBR2 depletion, histological OA scoring and pain assays; antibody neutralization in glomerulonephritis\",\n      \"pmids\": [\"37649532\", \"12368200\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical mechanism by which ITGA1 dampens TGFBR2 not defined\", \"Whether direct receptor cross-talk or indirect ECM remodeling mediates restraint unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed VLA-1/collagen-IV contact extends suppressive immune-cell interactions, implicating it in MDSC-mediated T cell suppression.\",\n      \"evidence\": \"Itga1-/- mice with intravital two-photon microscopy and in vivo suppression assays\",\n      \"pmids\": [\"33584706\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signaling consequence of prolonged contact in MDSCs not defined\", \"Generalizability beyond splenic red pulp unaddressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected CD49a to NK cell exhaustion and microglial neuroinflammation, positioning it as a therapeutic target in tumors and Parkinson's disease.\",\n      \"evidence\": \"CD49a knockout and antibody blockade across tumor models with anti-PD-L1 combination; conditional microglial Itga1 knockdown with PGAM5/NLRP3 and obtustatin antagonism\",\n      \"pmids\": [\"39570767\", \"41462565\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking CD49a engagement to NK exhaustion program not defined\", \"How ITGA1 controls PGAM5 expression in microglia unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined ITGA1 as a pro-tumorigenic effector across cancers acting through FAK, STAT3, and PI3K-Akt, with transcriptional and m6A-dependent control of its expression.\",\n      \"evidence\": \"Knockdown/inhibition (obtustatin) with rescue in retinoblastoma, glioblastoma, osteosarcoma; E2F1/TEAD1 ChIP and RBM15B MeRIP/mRNA-stability assays\",\n      \"pmids\": [\"40939856\", \"42020859\", \"40083708\", \"28264467\", \"38169150\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether collagen ligation or ligand-independent signaling drives tumor effects unclear\", \"Integration of FAK/STAT3/PI3K-Akt outputs not unified across tumor types\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single collagen/laminin receptor produces opposing outcomes\\u2014T cell retention, immune suppression, tissue protection, and tumor progression\\u2014depending on cell type remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking ligand context to divergent downstream signaling\", \"Structural basis of cell-type-specific ligand specificity uncharacterized\", \"Relative contribution of physical anchoring vs. signaling not separated across systems\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [1, 2, 6, 8]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [6, 5]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [28]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 14, 28]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [10, 13, 22, 24]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [1, 2, 12]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [27, 29, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [23, 24, 25, 30]}\n    ],\n    \"complexes\": [\"VLA-1 (integrin alpha1beta1)\"],\n    \"partners\": [\"ITGB1\", \"TGFBR2\", \"PGAM5\", \"THBS1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}