{"gene":"MADCAM1","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":1993,"finding":"Alpha 4 beta 7 integrin is a direct receptor for MAdCAM-1; antibodies to alpha 4 and beta 7 integrin chains (but not beta 2/LFA-1) inhibit lymphocyte binding to purified MAdCAM-1 and MAdCAM-1 transfectants; binding is enhanced by Mn2+-induced integrin activation; alpha 4 beta 7 preferentially binds MAdCAM-1 over VCAM-1, whereas alpha 4 beta 1 does not bind MAdCAM-1.","method":"Cell adhesion assays with purified MAdCAM-1 and MAdCAM-1 transfectants, blocking antibodies, Mn2+ activation, lymphoma cell lines","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — foundational paper with multiple orthogonal methods (pulldown on purified protein, transfectants, antibody blocking, integrin activation), >1200 citations, replicated across subsequent studies","pmids":["7687523"],"is_preprint":false},{"year":1993,"finding":"MAdCAM-1 isolated from mesenteric lymph nodes (but not from cultured endothelioma cells) bears N-glycanase-resistant sialic acid-containing carbohydrate that supports adhesion of L-selectin-transfected lymphoid cells under shear, identifying MAdCAM-1 as a facultative ligand for L-selectin; interacting cells display selectin-dependent 'rolling' behaviour.","method":"Biochemical isolation of MAdCAM-1, adhesion assays under shear flow using L-selectin transfectants, N-glycanase treatment","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro reconstitution under shear flow with biochemically characterized glycoprotein and transfected cells, replicated by subsequent studies; >470 citations","pmids":["7505053"],"is_preprint":false},{"year":1993,"finding":"Molecular cloning revealed that MAdCAM-1 is an immunoglobulin superfamily member with two N-terminal Ig domains (homologous to ICAM-1 and VCAM-1) involved in integrin binding, a serine/threonine-rich mucin-like region that presents carbohydrate ligands for selectin binding, and a membrane-proximal domain homologous to IgA1 C-alpha2.","method":"cDNA cloning, transfection into COS cells, binding assay with mucosal HEV-binding T-cell lymphoma TK1, sequence analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — functional expression cloning with direct binding validation; foundational structural definition paper, >350 citations","pmids":["8502297"],"is_preprint":false},{"year":1996,"finding":"Human MAdCAM-1 has two N-terminal Ig-like domains that are functionally conserved for alpha 4 beta 7 binding but lacks the IgA-like third domain; human MAdCAM-1 selectively binds alpha 4 beta 7-expressing lymphocyte cell lines from both human and mouse; expression is restricted to mucosal tissues, gut-associated lymphoid tissues, and spleen.","method":"Functional expression cloning using macaque/human libraries, cell adhesion assays with alpha 4 beta 7+ lymphocyte lines, RT-PCR tissue expression analysis","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — functional cloning plus direct binding assays; replicated by multiple subsequent studies","pmids":["8609404"],"is_preprint":false},{"year":1995,"finding":"The MAdCAM-1 gene is located on chromosome 10, contains 5 exons encoding distinct functional domains (signal peptide, each Ig domain, mucin/IgA domain, transmembrane/cytoplasmic), and an alternatively spliced variant lacking the mucin/IgA exon 4 exists; the 5' flanking region contains tandem NF-kB sites, AP-1, AP-2 binding sites, and an estrogen response element.","method":"Genomic cloning, RT-PCR, sequencing, chromosomal mapping, 5' promoter analysis","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — genomic characterization with functional promoter element identification; single study","pmids":["7650378"],"is_preprint":false},{"year":1997,"finding":"Site-directed mutagenesis identified the LDT sequence in the CD loop of MAdCAM-1's first Ig domain as a critical binding motif for alpha 4 beta 7 integrin adhesion and cell activation.","method":"Site-directed mutagenesis of MAdCAM-1, cell adhesion assays","journal":"Immunologic research","confidence":"Medium","confidence_rationale":"Tier 1 — mutagenesis approach; single study, limited methodological detail in abstract","pmids":["9379078"],"is_preprint":false},{"year":1997,"finding":"Alpha 4 integrin binding specificity for MAdCAM-1 versus VCAM-1 is determined not only by the critical aspartate in the CD loop, but also by accessory binding sites including an Ig domain 2 region; VCAM-1/MAdCAM-1 chimeras showed that the MAdCAM-1 adhesion motif in the context of VCAM-1 supports alpha 4 beta 1 binding, but the VCAM-1 motif in MAdCAM-1 context does not, implicating flanking structural determinants.","method":"VCAM-1/MAdCAM-1 chimera construction, recombinant protein cell adhesion assays, site-directed mutagenesis of VCAM-1","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — systematic chimera and mutagenesis approach with comprehensive mutant panel; identifies molecular basis of integrin selectivity","pmids":["9235944"],"is_preprint":false},{"year":1997,"finding":"Beta 7 integrin residues 46-386 specify alpha 4 beta 7 binding to MAdCAM-1; a MIDAS-like domain (residues 176-250) is critical for MAdCAM-1 and E-cadherin adhesion, mapped by seven blocking antibodies; residues 46-149 contain a Mn2+-dependent activating epitope that promotes MAdCAM-1 binding.","method":"Beta 7/beta 1 chimeras, human/mouse/rat chimeric beta 7 subunits, antibody epitope mapping, adhesion assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — systematic chimera analysis with comprehensive antibody panel; defines beta 7 structural determinants for MAdCAM-1 recognition","pmids":["9233649"],"is_preprint":false},{"year":1998,"finding":"Crystal structure of human MAdCAM-1 Ig domains 1 and 2 at 2.2 Å resolution reveals two integrin-recognition motifs: Asp42 in the CD loop of domain 1 (the key integrin-binding residue, stabilized by buried Arg70) and an unusual negatively charged beta ribbon extending from the D and E strands of domain 2, both on the same face; architectural differences in CD loops between MAdCAM-1 and VCAM-1 cause an 8 Å shift in the critical aspartate position.","method":"X-ray crystallography at 2.2 Å resolution, structural comparison","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure with functional interpretation; landmark structural paper","pmids":["9655832"],"is_preprint":false},{"year":1998,"finding":"MAdCAM-1 costimulates T cell proliferation exclusively through integrin alpha 4 beta 7 (not alpha 4 beta 1), whereas VCAM-1 and CS-1 peptide costimulate exclusively through alpha 4 beta 1; MAdCAM-1-Fc can synergize with and induce hyperresponsiveness to B7-2; costimulation occurs even when MAdCAM-1 is spatially distant from anti-CD3 ('remote' costimulation).","method":"T cell proliferation assays with immobilized Fc chimeras, blocking antibodies to specific integrin chains","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — clean functional assay with integrin-specific blocking; single study","pmids":["9842903"],"is_preprint":false},{"year":1998,"finding":"Secondary lymphoid-tissue chemokine (SLC/CCL21) immobilized on substrate rapidly activates alpha 4 beta 7-mediated lymphocyte adhesion to MAdCAM-1 under flow conditions through a pertussis toxin-sensitive (Gi-coupled) pathway; this effect is specific to SLC among CC chemokines tested.","method":"Flow chamber adhesion assays, pertussis toxin inhibition, blocking antibodies","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — flow-based adhesion assay with pharmacological dissection; single study","pmids":["9670974"],"is_preprint":false},{"year":2000,"finding":"Transcription factor NKX2.3 directly activates MAdCAM-1 transcription; NKX2.3-deficient mice lack MAdCAM-1 expression in mucosa-associated lymphoid tissue and spleen, resulting in failure of lymphocyte migration and homing to correct compartments.","method":"Gene knockout (NKX2.3-/-) mice, immunohistochemistry, RT-PCR, transcriptional activation assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 — genetic knockout combined with transcriptional activation evidence; replicated by second study (Wang CC et al., 2000)","pmids":["10790368","10926756"],"is_preprint":false},{"year":2001,"finding":"TNF-alpha induces MAdCAM-1 mRNA and protein in endothelial cells via tyrosine kinase, p42/44 MAPK, p38 MAPK, and NF-kB/PARP-dependent pathways; MEK-1/2 is activated by TNF-alpha within minutes and is dependent on TK and p42/44 MAPKs; MAdCAM-1 is frequently distributed to endothelial junctions both in vitro and in vivo.","method":"RT-PCR, Western blotting, pharmacological kinase inhibitors, immunofluorescence in endothelial cell lines (bEND.3 and SVEC)","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2 — systematic pharmacological dissection of signaling pathways in endothelial cells; single study with multiple inhibitors","pmids":["11546645"],"is_preprint":false},{"year":2001,"finding":"MAdCAM-1 expressed on inflamed hepatic portal vein/sinusoidal endothelium in autoimmune liver disease is functionally active, supporting alpha 4 beta 7+ lymphocyte adhesion (inhibited by anti-MAdCAM-1, anti-alpha 4 beta 7, anti-alpha 4 antibodies) and rolling under flow conditions.","method":"Modified Stamper-Woodruff binding assays, flow-based adhesion assays, blocking antibodies on human tissue sections","journal":"Hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — functional adhesion assays on human diseased tissue with multiple blocking antibodies; single study","pmids":["11343233"],"is_preprint":false},{"year":1996,"finding":"MAdCAM-1, VCAM-1, and ICAM-1 are expressed on choroid plexus epithelium (not endothelium) constitutively (ICAM-1, VCAM-1) or de novo during EAE (MAdCAM-1); these epithelial CAMs are locally synthesized and mediate lymphocyte binding via LFA-1 and alpha 4 integrin in Stamper-Woodruff assays, implicating the blood-CSF barrier epithelium in CNS immunosurveillance.","method":"Immunohistochemistry, in situ hybridization, cytokine stimulation of primary choroid plexus epithelial cells, Stamper-Woodruff binding assays","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods (ISH, IHC, functional binding assays) in EAE model; single study","pmids":["8669469"],"is_preprint":false},{"year":2002,"finding":"A revised crystal structure of human MAdCAM-1 Ig domains 1 and 2 shows one edge strand relocated to the opposite sheet compared with the first structure, altering the conformation of key integrin-binding residues; MAdCAM-1 forms dimers within the crystal lattice, suggesting oligomerization may influence biological function.","method":"X-ray crystallography (second crystal form), structural comparison","journal":"Acta crystallographica. Section D, Biological crystallography","confidence":"Medium","confidence_rationale":"Tier 1 — crystal structure, but represents a reanalysis/revision of prior structure; single study with limited functional validation","pmids":["11807247"],"is_preprint":false},{"year":2008,"finding":"Immobilized CCL25 and CCL28 specifically trigger alpha 4 beta 7-dependent lymphocyte arrest on MAdCAM-1 under shear flow without affecting adhesion to VCAM-1; alpha 4 beta 7/MAdCAM-1 and alpha 4 beta 1/VCAM-1 operate as independent adhesion pathways; CCL21 and CXCL12 trigger a motile phenotype (lamellipodia/uropod) after arrest on MAdCAM-1.","method":"Flow-based adhesion assays, integrin-specific blocking antibodies, immobilized chemokines","journal":"American journal of physiology. Gastrointestinal and liver physiology","confidence":"Medium","confidence_rationale":"Tier 2 — systematic flow assay with pharmacological and antibody dissection; single study","pmids":["18308860"],"is_preprint":false},{"year":2009,"finding":"GlcNAc6ST-1 preferentially utilizes MAdCAM-1 protein as a scaffold for GlcNAc-6-O-sulfation in L-selectin ligand carbohydrate biosynthesis; co-localization of MAdCAM-1 and L-selectin ligand carbohydrates (MECA-79 epitope) at luminal surface of HEV-like vessels was demonstrated, and UC disease activity correlates with GlcNAc6ST-1-mediated decoration rather than MAdCAM-1 protein levels per se.","method":"RT-PCR, immunofluorescence, FACS, Western blotting of CHO/Lec2 transfectants co-expressing MAdCAM-1 with GlcNAc6ST enzymes, immunohistochemistry","journal":"Inflammatory bowel diseases","confidence":"Medium","confidence_rationale":"Tier 1-2 — direct biochemical demonstration of enzymatic modification of MAdCAM-1 in transfected cells; single study","pmids":["19067429"],"is_preprint":false},{"year":2011,"finding":"The CC' loop of MAdCAM-1 Ig domain 1 (including Asp-42) is indispensable for binding both low- and high-affinity alpha 4 beta 7; the DE loop of domain 2 is required for binding to inactive and SDF-1alpha/talin-activated alpha 4 beta 7 but is less critical for Mn2+-activated alpha 4 beta 7, indicating distinct conformational requirements for MAdCAM-1 binding to different integrin activation states.","method":"Site-directed mutagenesis of MAdCAM-1 CC' and DE loops, cell adhesion assays with Mn2+- or chemokine/talin-activated alpha 4 beta 7","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 — systematic mutagenesis combined with multiple integrin activation conditions; single study","pmids":["21296888"],"is_preprint":false},{"year":2004,"finding":"Alpha 4 beta 7 on hematopoietic progenitor cells (HPCs) mediates tethering and rolling on MAdCAM-1 in bone marrow (demonstrated by intravital microscopy); blocking MAdCAM-1 significantly reduces HPC homing after bone marrow transplantation, contributing to approximately half of all alpha 4 integrin-mediated homing activity.","method":"Flow cytometry, CXCL12-stimulated adhesion to immobilized MAdCAM-1, BM intravital microscopy, homing assays with blocking antibodies","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods (intravital microscopy, adhesion assays, in vivo homing); single study","pmids":["15161666"],"is_preprint":false},{"year":2009,"finding":"Angiotensin II type 1 receptor (AT1R) regulates TNF-alpha-induced MAdCAM-1 expression via NF-kB nuclear translocation (but not p38 MAPK or IkB phosphorylation); AT1R-deficient mice show reduced MAdCAM-1 expression and attenuated DSS-induced colitis.","method":"AT1R blocker treatment and AT1R-/- mice, Western blotting, NF-kB translocation assays, DSS colitis model","journal":"American journal of physiology. Gastrointestinal and liver physiology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic knockout combined with pharmacological inhibition and mechanistic assays; single study","pmids":["19940029"],"is_preprint":false},{"year":2014,"finding":"MAdCAM-1 mediates intestinal localization of dendritic cells (conventional DCs and plasmacytoid DCs) via beta 7 integrin; MAdCAM-1-deficient and beta 7 integrin-deficient mice both show reduced CD11c+ cells and plasmacytoid DCs in gut epithelium, and reduced migration efficiency of pDC and cDC precursors into the intraepithelial compartment.","method":"MAdCAM-1 knockout mice, beta 7 integrin knockout mice, flow cytometry, migration assays","journal":"Clinical immunology","confidence":"Medium","confidence_rationale":"Tier 2 — parallel knockout mouse models with defined cellular phenotype; single study","pmids":["25464027"],"is_preprint":false},{"year":2015,"finding":"Beta 7 integrin on hematopoietic stem cells (HSCs) interacts with MAdCAM-1 on bone marrow endothelial cells to promote HSC homing and engraftment; lethal irradiation induces MAdCAM-1 expression on BM endothelial cells; blocking MAdCAM-1 reduces HSC homing and impairs recipient survival; beta 7 KO HSCs have reduced CXCR4 expression and impaired migration.","method":"Flow cytometry, quantitative RT-PCR, in vivo homing assays, BM transplantation with blocking antibodies, beta 7 KO mice","journal":"Stem cells and development","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo homing assays plus genetic knockout; single study","pmids":["26422691"],"is_preprint":false},{"year":2022,"finding":"MAdCAM-1-expressing lymphoid stromal cells in lymph nodes are among the first cells to respond to immunization, proliferating and upregulating podoplanin and cell adhesion molecules; this response is abrogated in aged mice; TLR4 activation with adjuvants directly stimulates MAdCAM-1+ stromal cells (shown by bone marrow chimeras) and improves the germinal center response in both young and aged mice.","method":"Heterochronic parabiosis, mouse immunization, bone marrow chimeras, flow cytometry of MAdCAM-1+ stromal cells","journal":"Science immunology","confidence":"Medium","confidence_rationale":"Tier 2 — heterochronic parabiosis and BM chimera experiments with defined cellular readouts; single study","pmids":["35522725"],"is_preprint":false},{"year":2017,"finding":"MAdCAM-1 promotes steatohepatitis development: MAdCAM-1-deficient mice show reduced hepatic inflammation, enhanced anti-oxidative stress (Nrf2, HO-1 upregulation), increased regulatory T cells and anti-inflammatory macrophages, and are protected from fibrosis initiation in high fat diet and methionine-choline-deficient diet models.","method":"MAdCAM-1 knockout mice, beta 7 integrin knockout mice, high fat diet / MCD diet models, histomorphology, flow cytometry, dihydroethidium staining","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — parallel knockout mouse models with multiple mechanistic readouts; single study","pmids":["28192190"],"is_preprint":false},{"year":1998,"finding":"LPAM-1 (alpha 4 beta 7) binds to MAdCAM-1 and VCAM-1 via overlapping binding sites that overlap with the RGD recognition site; fibrinogen at physiological concentrations partially blocks TK-1 cell binding to MAdCAM-1, suggesting endogenous RGD-containing vascular proteins can compete with MAdCAM-1.","method":"Cell adhesion assays with RGD-containing peptides/polymers, fibrinogen competition, blocking antibodies","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — competition adhesion assays; single study","pmids":["9541595"],"is_preprint":false},{"year":2001,"finding":"In utero and during early childhood, MAdCAM-1 is widely expressed (not restricted to mucosal sites) and functionally governs lymphocyte adhesion to both gut and peripheral lymph node vessels via alpha 4 beta 7 integrin; after birth, MAdCAM-1 expression gradually becomes mucosal-restricted as PNAd/L-selectin interactions take over peripheral node adhesion.","method":"Immunostaining of human fetal and pediatric tissues, in vitro binding assays with blocking antibodies on tissue sections","journal":"Gastroenterology","confidence":"Medium","confidence_rationale":"Tier 2 — functional binding assays on human tissues across developmental stages; single study","pmids":["11606499"],"is_preprint":false},{"year":2002,"finding":"Exogenous NO donors (DETA-NO, SperNO) inhibit TNF-alpha-stimulated MAdCAM-1 expression in endothelial cells and reduce alpha 4 beta 7-dependent lymphocyte adhesion; inhibition of endogenous NO production (L-NAME, 1400W) does not induce or potentiate TNF-alpha-regulated MAdCAM-1 expression, distinguishing exogenous from endogenous NO regulation.","method":"Western blotting of MAdCAM-1 after NO donor/inhibitor pre-treatment, lymphocyte adhesion assays","journal":"BMC gastroenterology","confidence":"Low","confidence_rationale":"Tier 3 — pharmacological study in cell line; single study, limited mechanistic depth","pmids":["11481030"],"is_preprint":false},{"year":2004,"finding":"P-selectin and MAdCAM-1 are co-expressed on maternal vessels during placenta development; long-term in vivo MAdCAM-1 blockade reduces recruitment of alpha 4 beta 7+ monocyte-like cells to the decidua, and absence of these cells is associated with reduced uterine NK cell numbers.","method":"In vivo antibody blockade, knockout mouse strains lacking specific adhesion receptors, immunohistochemistry","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo long-term blockade plus genetic models with defined cellular readouts; single study","pmids":["15484189"],"is_preprint":false}],"current_model":"MAdCAM-1 is an endothelial immunoglobulin superfamily adhesion molecule whose two N-terminal Ig domains (with critical Asp42 in the CD loop and an accessory DE-loop beta ribbon) bind preferentially to integrin alpha 4 beta 7 on lymphocytes and other leukocytes to mediate tethering, rolling, and firm adhesion at mucosal and inflamed tissues; its mucin-like domain, when decorated by GlcNAc6ST-1-mediated sialylated carbohydrates, additionally acts as a facultative L-selectin ligand; expression is transcriptionally controlled by NF-kB (downstream of TNF-alpha via MAPK and AT1R pathways) and by the homeodomain factor NKX2.3, while exogenous NO and IL-10 suppress its induction; the alpha 4 beta 7–MAdCAM-1 axis directs lymphocyte, dendritic cell, and hematopoietic progenitor homing to gut-associated lymphoid tissues, bone marrow, and inflamed mucosal sites, and its blockade reduces intestinal inflammation in multiple animal models."},"narrative":{"teleology":[{"year":1993,"claim":"Identification of α4β7 integrin as the specific lymphocyte receptor for MAdCAM-1 established the molecular basis for mucosal-selective lymphocyte adhesion, resolving how MAdCAM-1 functions distinctly from VCAM-1.","evidence":"Cell adhesion assays with purified MAdCAM-1, blocking antibodies against α4, β7, β2 chains, and Mn2+ activation using lymphoma cell lines","pmids":["7687523"],"confidence":"High","gaps":["Structural basis of α4β7 versus α4β1 selectivity not yet defined","In vivo relevance of preferential binding not demonstrated"]},{"year":1993,"claim":"Molecular cloning and biochemical characterization revealed MAdCAM-1 as a dual-function molecule — its Ig domains bind integrins while its mucin domain presents carbohydrates for L-selectin, explaining how a single endothelial molecule can mediate both selectin-dependent rolling and integrin-dependent arrest.","evidence":"cDNA cloning with COS cell expression and binding assays; parallel shear-flow adhesion assays with L-selectin transfectants and N-glycanase-treated MAdCAM-1 purified from mesenteric lymph nodes","pmids":["8502297","7505053"],"confidence":"High","gaps":["Carbohydrate modifications responsible for L-selectin binding not molecularly defined","In vivo contribution of mucin domain versus Ig domains to homing not separated"]},{"year":1995,"claim":"Genomic characterization revealed tandem NF-κB sites in the MAdCAM-1 promoter, providing the first mechanistic link between inflammatory signaling and MAdCAM-1 transcriptional induction.","evidence":"Genomic cloning, sequencing, and 5′ promoter analysis of MAdCAM-1 gene (5 exons, chromosome 10)","pmids":["7650378"],"confidence":"Medium","gaps":["NF-κB sites not yet validated by reporter or ChIP assays","Alternative splicing functional consequences unknown"]},{"year":1996,"claim":"Cloning of human MAdCAM-1 confirmed conservation of α4β7 binding via two N-terminal Ig domains and established mucosal-restricted expression, while showing loss of the IgA-like third domain — demonstrating species-specific structural variation.","evidence":"Functional expression cloning from macaque/human libraries, adhesion assays, RT-PCR tissue panel","pmids":["8609404"],"confidence":"High","gaps":["Functional consequence of missing IgA domain in humans not determined"]},{"year":1997,"claim":"Systematic mutagenesis and chimera studies defined the bipartite integrin-binding surface: the LDT/Asp42 motif in the CD loop of Ig domain 1 is essential, while flanking structural context (including Ig domain 2) determines α4β7 versus α4β1 selectivity.","evidence":"Site-directed mutagenesis, VCAM-1/MAdCAM-1 chimera construction, and cell adhesion assays; parallel β7/β1 chimera mapping of integrin MIDAS-like domain","pmids":["9379078","9235944","9233649"],"confidence":"High","gaps":["Atomic-resolution view of integrin–MAdCAM-1 interface not yet available","Role of each Ig domain in activation-state-dependent binding not dissected"]},{"year":1998,"claim":"The crystal structure of MAdCAM-1 Ig domains 1–2 at 2.2 Å resolution revealed how Asp42 is stabilized by buried Arg70 and identified the unusual DE-loop β-ribbon of domain 2 as a second integrin-contact surface, explaining mutagenesis data and the 8 Å displacement of the critical aspartate relative to VCAM-1.","evidence":"X-ray crystallography at 2.2 Å resolution with structural comparison to VCAM-1","pmids":["9655832"],"confidence":"High","gaps":["No co-crystal with α4β7; exact integrin–ligand interface still modeled","Revised crystal form later raised questions about edge-strand assignment (PMID:11807247)"]},{"year":1998,"claim":"Demonstration that MAdCAM-1 costimulates T cell proliferation exclusively through α4β7 (not α4β1) and that chemokine CCL21 rapidly triggers α4β7-dependent arrest on MAdCAM-1 under flow established MAdCAM-1 as an active participant in lymphocyte activation and chemokine-directed adhesion cascades.","evidence":"T cell proliferation assays with immobilized Fc chimeras and blocking antibodies; flow chamber adhesion assays with pertussis toxin inhibition","pmids":["9842903","9670974"],"confidence":"Medium","gaps":["Costimulatory signaling pathway downstream of α4β7 not characterized","Range of chemokines capable of triggering MAdCAM-1 arrest incompletely surveyed"]},{"year":2000,"claim":"Genetic ablation of NKX2.3 eliminated MAdCAM-1 expression in mucosal lymphoid tissue and disrupted lymphocyte compartmentalization, establishing NKX2.3 as a master transcriptional regulator of tissue-selective MAdCAM-1 expression.","evidence":"NKX2.3 knockout mice, immunohistochemistry, RT-PCR, transcriptional activation assays","pmids":["10790368","10926756"],"confidence":"High","gaps":["Whether NKX2.3 directly binds the MAdCAM-1 promoter (ChIP) not shown","Relationship between NKX2.3 and NF-κB in MAdCAM-1 regulation not addressed"]},{"year":2001,"claim":"TNF-α–induced MAdCAM-1 expression was shown to require convergent MAPK and NF-κB/PARP signaling in endothelial cells, and MAdCAM-1 was found to localize to endothelial junctions — connecting inflammatory cytokine signaling to adhesion molecule positioning for leukocyte transmigration.","evidence":"RT-PCR, Western blotting, pharmacological kinase inhibitors in bEND.3 and SVEC endothelial cells, immunofluorescence","pmids":["11546645"],"confidence":"Medium","gaps":["PARP role in NF-κB-dependent MAdCAM-1 transcription not mechanistically detailed","Junction localization functional consequences not tested"]},{"year":2001,"claim":"MAdCAM-1 expression during fetal life is widespread rather than mucosal-restricted, with postnatal restriction occurring as PNAd/L-selectin pathways replace α4β7/MAdCAM-1 in peripheral lymph nodes — redefining MAdCAM-1 as a developmentally regulated pan-lymphoid adhesion molecule.","evidence":"Immunostaining and functional binding assays on human fetal and pediatric tissues with blocking antibodies","pmids":["11606499"],"confidence":"Medium","gaps":["Signals driving postnatal downregulation of MAdCAM-1 in peripheral nodes not identified","Functional consequences of fetal widespread expression not tested in vivo"]},{"year":2004,"claim":"α4β7/MAdCAM-1 interaction was shown to mediate hematopoietic progenitor cell tethering and rolling in bone marrow by intravital microscopy, extending MAdCAM-1 function beyond mucosal lymphocyte homing to hematopoietic stem cell engraftment.","evidence":"Intravital microscopy of bone marrow, in vivo homing assays with MAdCAM-1-blocking antibodies, CXCL12-stimulated adhesion assays","pmids":["15161666"],"confidence":"Medium","gaps":["Relative contribution of MAdCAM-1 versus VCAM-1 in BM homing not fully quantified","Whether MAdCAM-1 is constitutive or induced on BM endothelium under homeostasis unclear"]},{"year":2009,"claim":"Two advances refined MAdCAM-1 regulation and function: GlcNAc6ST-1 was identified as the sulfotransferase that preferentially modifies MAdCAM-1 to generate L-selectin ligand carbohydrates, and AT1R was shown to regulate TNF-α-induced MAdCAM-1 expression via NF-κB nuclear translocation, linking the renin-angiotensin system to mucosal inflammation.","evidence":"Transfection of CHO cells co-expressing MAdCAM-1 with GlcNAc6ST enzymes, FACS, Western blotting; AT1R-/- mice and pharmacological blockade in DSS colitis model","pmids":["19067429","19940029"],"confidence":"Medium","gaps":["Whether AT1R directly activates NF-κB or acts through intermediate kinases not resolved","In vivo contribution of GlcNAc6ST-1-modified MAdCAM-1 to L-selectin-dependent rolling not tested genetically"]},{"year":2011,"claim":"Mutagenesis of the CC' and DE loops showed that MAdCAM-1 engages different integrin activation states through distinct structural elements — the CC' loop/Asp42 is universally required, while the DE loop β-ribbon of domain 2 is dispensable for fully activated (Mn2+) but essential for physiologically activated α4β7.","evidence":"Site-directed mutagenesis of MAdCAM-1 CC' and DE loops, adhesion assays with Mn2+-, chemokine-, and talin-activated α4β7","pmids":["21296888"],"confidence":"Medium","gaps":["No co-crystal structure of MAdCAM-1 with α4β7 in any activation state","How talin-induced versus Mn2+-induced conformational changes alter the integrin footprint on MAdCAM-1 not structurally resolved"]},{"year":2014,"claim":"MAdCAM-1/β7 axis was shown to govern intestinal localization of dendritic cells (both conventional and plasmacytoid), broadening MAdCAM-1's functional role beyond lymphocyte homing to innate immune cell positioning in the gut.","evidence":"MAdCAM-1 knockout and β7 integrin knockout mice, flow cytometry, migration assays","pmids":["25464027"],"confidence":"Medium","gaps":["Specific integrin heterodimer on DCs mediating MAdCAM-1 binding not identified","Functional consequence of reduced gut DCs on mucosal immunity not assessed"]},{"year":2017,"claim":"MAdCAM-1 deficiency protected mice from diet-induced steatohepatitis by shifting immune balance toward regulatory T cells and anti-inflammatory macrophages, establishing MAdCAM-1 as a driver of hepatic inflammatory recruitment beyond its classical mucosal role.","evidence":"MAdCAM-1 and β7 knockout mice on high-fat and MCD diets, histomorphology, flow cytometry, oxidative stress markers","pmids":["28192190"],"confidence":"Medium","gaps":["Whether hepatic MAdCAM-1 is endothelial or stromal in origin not determined","Mechanism linking MAdCAM-1 to Nrf2/HO-1 upregulation not elucidated"]},{"year":2022,"claim":"MAdCAM-1-expressing lymph node stromal cells were identified as early responders to immunization, and their age-dependent decline was shown to impair germinal center responses — revealing a non-endothelial, stromal role for MAdCAM-1+ cells in adaptive immunity.","evidence":"Heterochronic parabiosis, mouse immunization, bone marrow chimeras, flow cytometry","pmids":["35522725"],"confidence":"Medium","gaps":["Whether MAdCAM-1 itself signals in stromal cells or merely marks them is unknown","TLR4-dependent mechanism of stromal cell activation not molecularly defined"]},{"year":null,"claim":"A co-crystal structure of MAdCAM-1 bound to α4β7 integrin in physiological activation states is still lacking, and the signaling pathways downstream of MAdCAM-1 engagement in both endothelial and stromal cells remain undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No atomic-resolution α4β7–MAdCAM-1 complex structure","Intracellular signaling triggered by MAdCAM-1 ligation in endothelial cells not characterized","How MAdCAM-1+ stromal cells contribute to germinal center formation mechanistically is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,1,2,8]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,3,12]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[1,17]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,1,11,21]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[0,2,6,8]}],"complexes":[],"partners":["ITGA4","ITGB7","SELL","NKX2-3","CHST2"],"other_free_text":[]},"mechanistic_narrative":"MAdCAM-1 is an endothelial immunoglobulin superfamily adhesion molecule that directs tissue-selective lymphocyte, dendritic cell, and hematopoietic progenitor homing to gut-associated lymphoid tissues and bone marrow through its role as the dominant ligand for integrin α4β7. Its two N-terminal Ig domains present a critical Asp42 residue in the CD loop of domain 1 and an accessory negatively charged β-ribbon in the DE loop of domain 2, which together form a bipartite α4β7-binding surface whose engagement supports tethering, rolling, and firm adhesion under shear flow; the mucin-like domain, when decorated with GlcNAc6ST-1-dependent sulfated sialyl carbohydrates, additionally serves as a facultative L-selectin ligand [PMID:7687523, PMID:9655832, PMID:7505053, PMID:19067429]. MAdCAM-1 transcription is driven by NF-κB (activated downstream of TNF-α via MAPK and AT1R signaling) and the homeodomain factor NKX2.3, whose genetic ablation eliminates mucosal MAdCAM-1 expression and disrupts lymphocyte compartmentalization [PMID:10790368, PMID:11546645, PMID:19940029]. Chemokines CCL25, CCL28, and CCL21 presented on the endothelial surface rapidly trigger α4β7-dependent arrest on MAdCAM-1 through Gi-coupled signaling, and blockade of the α4β7–MAdCAM-1 axis reduces intestinal inflammation, hepatic steatohepatitis, and impairs hematopoietic stem cell engraftment in bone marrow transplantation models [PMID:18308860, PMID:9670974, PMID:28192190, PMID:26422691]."},"prefetch_data":{"uniprot":{"accession":"Q13477","full_name":"Mucosal addressin cell adhesion molecule 1","aliases":[],"length_aa":382,"mass_kda":40.2,"function":"Cell adhesion leukocyte receptor expressed by mucosal venules, helps to direct lymphocyte traffic into mucosal tissues including the Peyer patches and the intestinal lamina propria. It can bind both integrin alpha-4/beta-7 and L-selectin, regulating both the passage and retention of leukocytes. Isoform 2, lacking the mucin-like domain, may be specialized in supporting integrin alpha-4/beta-7-dependent adhesion strengthening, independent of L-selectin binding","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q13477/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MADCAM1","classification":"Not Classified","n_dependent_lines":27,"n_total_lines":1208,"dependency_fraction":0.022350993377483443},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MADCAM1","total_profiled":1310},"omim":[{"mim_id":"613806","title":"CHOLANGITIS, PRIMARY SCLEROSING; PSC","url":"https://www.omim.org/entry/613806"},{"mim_id":"606727","title":"NK2 HOMEOBOX 3; NKX2-3","url":"https://www.omim.org/entry/606727"},{"mim_id":"604738","title":"CHEMOKINE, CC MOTIF, RECEPTOR 9; CCR9","url":"https://www.omim.org/entry/604738"},{"mim_id":"604520","title":"TUMOR NECROSIS FACTOR LIGAND SUPERFAMILY, MEMBER 14; TNFSF14","url":"https://www.omim.org/entry/604520"},{"mim_id":"602565","title":"CHEMOKINE, CC MOTIF, LIGAND 25; CCL25","url":"https://www.omim.org/entry/602565"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"intestine","ntpm":11.7},{"tissue":"lymphoid tissue","ntpm":13.1}],"url":"https://www.proteinatlas.org/search/MADCAM1"},"hgnc":{"alias_symbol":["MACAM1"],"prev_symbol":[]},"alphafold":{"accession":"Q13477","domains":[{"cath_id":"2.60.40.10","chopping":"26-113","consensus_level":"high","plddt":90.4702,"start":26,"end":113},{"cath_id":"2.60.40.10","chopping":"118-223","consensus_level":"high","plddt":93.2527,"start":118,"end":223}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13477","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13477-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13477-F1-predicted_aligned_error_v6.png","plddt_mean":74.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MADCAM1","jax_strain_url":"https://www.jax.org/strain/search?query=MADCAM1"},"sequence":{"accession":"Q13477","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13477.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13477/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13477"}},"corpus_meta":[{"pmid":"7687523","id":"PMC_7687523","title":"Alpha 4 beta 7 integrin mediates lymphocyte binding to the mucosal vascular addressin MAdCAM-1.","date":"1993","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/7687523","citation_count":1286,"is_preprint":false},{"pmid":"7505053","id":"PMC_7505053","title":"L-selectin-mediated lymphocyte rolling on MAdCAM-1.","date":"1993","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/7505053","citation_count":477,"is_preprint":false},{"pmid":"8502297","id":"PMC_8502297","title":"MAdCAM-1 has homology to immunoglobulin and mucin-like adhesion receptors and to IgA1.","date":"1993","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/8502297","citation_count":350,"is_preprint":false},{"pmid":"7517418","id":"PMC_7517418","title":"Expression and function of the MAdCAM-1 receptor, integrin alpha 4 beta 7, on human leukocytes.","date":"1994","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/7517418","citation_count":317,"is_preprint":false},{"pmid":"9036954","id":"PMC_9036954","title":"Monoclonal antibodies specific for beta 7 integrin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) reduce inflammation in the colon of scid mice reconstituted with CD45RBhigh CD4+ T cells.","date":"1997","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9036954","citation_count":273,"is_preprint":false},{"pmid":"11343233","id":"PMC_11343233","title":"MAdCAM-1 expressed in chronic inflammatory liver disease supports mucosal lymphocyte adhesion to hepatic endothelium (MAdCAM-1 in chronic inflammatory liver disease).","date":"2001","source":"Hepatology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/11343233","citation_count":217,"is_preprint":false},{"pmid":"8669469","id":"PMC_8669469","title":"ICAM-1, VCAM-1, and MAdCAM-1 are expressed on choroid plexus epithelium but not endothelium and mediate binding of lymphocytes in vitro.","date":"1996","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/8669469","citation_count":203,"is_preprint":false},{"pmid":"11045571","id":"PMC_11045571","title":"VCAM-1, but not ICAM-1 or MAdCAM-1, immunoblockade ameliorates DSS-induced colitis in mice.","date":"2000","source":"Laboratory investigation; 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Mucosal Transmission of SHIV-SF162P3.","date":"2016","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/27348748","citation_count":15,"is_preprint":false},{"pmid":"12390304","id":"PMC_12390304","title":"Increased expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and lymphocyte recruitment in murine gastritis induced by Helicobacter pylori.","date":"2002","source":"Clinical and experimental immunology","url":"https://pubmed.ncbi.nlm.nih.gov/12390304","citation_count":15,"is_preprint":false},{"pmid":"21073611","id":"PMC_21073611","title":"Induction of high endothelial venule-like vessels expressing GlcNAc6ST-1-mediated L-selectin ligand carbohydrate and mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in a mouse model of \"Candidatus Helicobacter heilmannii\"-induced gastritis and gastric mucosa-associated lymphoid tissue (MALT) lymphoma.","date":"2010","source":"Helicobacter","url":"https://pubmed.ncbi.nlm.nih.gov/21073611","citation_count":15,"is_preprint":false},{"pmid":"12625840","id":"PMC_12625840","title":"Transfection of IL-10 expression vectors into endothelial cultures attenuates alpha4beta7-dependent lymphocyte adhesion mediated by MAdCAM-1.","date":"2003","source":"BMC gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/12625840","citation_count":15,"is_preprint":false},{"pmid":"9058828","id":"PMC_9058828","title":"Rat mast cell lines bind to the vascular cell adhesion molecule-1 (VCAM-1) and the mucosal addressin cell adhesion molecule-1 (MAdCAM-1).","date":"1997","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9058828","citation_count":15,"is_preprint":false},{"pmid":"11807247","id":"PMC_11807247","title":"A reassessment of the MAdCAM-1 structure and its role in integrin recognition.","date":"2002","source":"Acta crystallographica. Section D, Biological crystallography","url":"https://pubmed.ncbi.nlm.nih.gov/11807247","citation_count":15,"is_preprint":false},{"pmid":"14670821","id":"PMC_14670821","title":"Chronic allergy to dietary ovalbumin induces lymphocyte migration to rat small intestinal mucosa that is inhibited by MAdCAM-1.","date":"2003","source":"American journal of physiology. Gastrointestinal and liver physiology","url":"https://pubmed.ncbi.nlm.nih.gov/14670821","citation_count":15,"is_preprint":false},{"pmid":"9873398","id":"PMC_9873398","title":"Novel modified tripeptide inhibitors of alpha 4 beta 7 mediated lymphoid cell adhesion to MAdCAM-1.","date":"1998","source":"Bioorganic & medicinal chemistry letters","url":"https://pubmed.ncbi.nlm.nih.gov/9873398","citation_count":14,"is_preprint":false},{"pmid":"9162097","id":"PMC_9162097","title":"Genomic organization, chromosomal mapping, and analysis of the 5' promoter region of the human MAdCAM-1 gene.","date":"1997","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/9162097","citation_count":14,"is_preprint":false},{"pmid":"35784193","id":"PMC_35784193","title":"Vedolizumab blocks α4β7 integrin-mediated T cell adhesion to MAdCAM-1 in microscopic colitis.","date":"2022","source":"Therapeutic advances in gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/35784193","citation_count":12,"is_preprint":false},{"pmid":"11472325","id":"PMC_11472325","title":"Glucocorticoids and IL-10, but not 6-MP, 5-ASA or sulfasalazine block endothelial expression of MAdCAM-1: implications for inflammatory bowel disease therapy.","date":"2001","source":"Alimentary pharmacology & therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/11472325","citation_count":12,"is_preprint":false},{"pmid":"27016601","id":"PMC_27016601","title":"Glucocorticoids Suppress CCR9-Mediated Chemotaxis, Calcium Flux, and Adhesion to MAdCAM-1 in Human T Cells.","date":"2016","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/27016601","citation_count":11,"is_preprint":false},{"pmid":"18633157","id":"PMC_18633157","title":"Role of MAdCAM-1 and its ligand on the homing of transplanted hematopoietic cells in irradiated mice.","date":"2008","source":"Experimental animals","url":"https://pubmed.ncbi.nlm.nih.gov/18633157","citation_count":11,"is_preprint":false},{"pmid":"21296888","id":"PMC_21296888","title":"The CC' and DE loops in Ig domains 1 and 2 of MAdCAM-1 play different roles in MAdCAM-1 binding to low- and high-affinity integrin alpha4beta7.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21296888","citation_count":11,"is_preprint":false},{"pmid":"34827121","id":"PMC_34827121","title":"Circulating MAdCAM-1 and ITGB7 in Patients with Plaque Psoriasis and Eruptive Lichen Planus-Preliminary Data.","date":"2021","source":"Biology","url":"https://pubmed.ncbi.nlm.nih.gov/34827121","citation_count":10,"is_preprint":false},{"pmid":"9512658","id":"PMC_9512658","title":"Cloning and characterization of the rat MAdCAM-1 cDNA and gene.","date":"1998","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/9512658","citation_count":10,"is_preprint":false},{"pmid":"32268498","id":"PMC_32268498","title":"Development of Mucosal PNAd+ and MAdCAM-1+ Venules during Disease Course in Ulcerative Colitis.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/32268498","citation_count":9,"is_preprint":false},{"pmid":"19286444","id":"PMC_19286444","title":"Possible impact of MADCAM1 gene single nucleotide polymorphisms to the outcome of allogeneic hematopoietic stem cell transplantation.","date":"2009","source":"Human immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19286444","citation_count":9,"is_preprint":false},{"pmid":"33675360","id":"PMC_33675360","title":"Expression of MAdCAM-1 and Gut-homing T Cells in Inflamed Pouch Mucosa.","date":"2021","source":"Journal of Crohn's & colitis","url":"https://pubmed.ncbi.nlm.nih.gov/33675360","citation_count":9,"is_preprint":false},{"pmid":"32908005","id":"PMC_32908005","title":"Ultrasensitive molecular imaging of intestinal mucosal inflammation using leukocyte-mimicking particles targeted to MAdCAM-1 in mice.","date":"2020","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32908005","citation_count":9,"is_preprint":false},{"pmid":"17202440","id":"PMC_17202440","title":"Parenteral nutrition and fasting reduces mucosal addressin cellular adhesion molecule-1 (MAdCAM-1) mRNA in Peyer's patches of mice.","date":"2007","source":"JPEN. Journal of parenteral and enteral nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/17202440","citation_count":9,"is_preprint":false},{"pmid":"17493530","id":"PMC_17493530","title":"Effect of blocking the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in a rat small intestinal transplantation model.","date":"2007","source":"Transplant immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17493530","citation_count":9,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":54553,"output_tokens":7253,"usd":0.136227},"stage2":{"model":"claude-opus-4-6","input_tokens":10920,"output_tokens":4253,"usd":0.241388},"total_usd":0.377615,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"Alpha 4 beta 7 integrin is a direct receptor for MAdCAM-1; antibodies to alpha 4 and beta 7 integrin chains (but not beta 2/LFA-1) inhibit lymphocyte binding to purified MAdCAM-1 and MAdCAM-1 transfectants; binding is enhanced by Mn2+-induced integrin activation; alpha 4 beta 7 preferentially binds MAdCAM-1 over VCAM-1, whereas alpha 4 beta 1 does not bind MAdCAM-1.\",\n      \"method\": \"Cell adhesion assays with purified MAdCAM-1 and MAdCAM-1 transfectants, blocking antibodies, Mn2+ activation, lymphoma cell lines\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — foundational paper with multiple orthogonal methods (pulldown on purified protein, transfectants, antibody blocking, integrin activation), >1200 citations, replicated across subsequent studies\",\n      \"pmids\": [\"7687523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"MAdCAM-1 isolated from mesenteric lymph nodes (but not from cultured endothelioma cells) bears N-glycanase-resistant sialic acid-containing carbohydrate that supports adhesion of L-selectin-transfected lymphoid cells under shear, identifying MAdCAM-1 as a facultative ligand for L-selectin; interacting cells display selectin-dependent 'rolling' behaviour.\",\n      \"method\": \"Biochemical isolation of MAdCAM-1, adhesion assays under shear flow using L-selectin transfectants, N-glycanase treatment\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro reconstitution under shear flow with biochemically characterized glycoprotein and transfected cells, replicated by subsequent studies; >470 citations\",\n      \"pmids\": [\"7505053\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"Molecular cloning revealed that MAdCAM-1 is an immunoglobulin superfamily member with two N-terminal Ig domains (homologous to ICAM-1 and VCAM-1) involved in integrin binding, a serine/threonine-rich mucin-like region that presents carbohydrate ligands for selectin binding, and a membrane-proximal domain homologous to IgA1 C-alpha2.\",\n      \"method\": \"cDNA cloning, transfection into COS cells, binding assay with mucosal HEV-binding T-cell lymphoma TK1, sequence analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — functional expression cloning with direct binding validation; foundational structural definition paper, >350 citations\",\n      \"pmids\": [\"8502297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Human MAdCAM-1 has two N-terminal Ig-like domains that are functionally conserved for alpha 4 beta 7 binding but lacks the IgA-like third domain; human MAdCAM-1 selectively binds alpha 4 beta 7-expressing lymphocyte cell lines from both human and mouse; expression is restricted to mucosal tissues, gut-associated lymphoid tissues, and spleen.\",\n      \"method\": \"Functional expression cloning using macaque/human libraries, cell adhesion assays with alpha 4 beta 7+ lymphocyte lines, RT-PCR tissue expression analysis\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — functional cloning plus direct binding assays; replicated by multiple subsequent studies\",\n      \"pmids\": [\"8609404\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"The MAdCAM-1 gene is located on chromosome 10, contains 5 exons encoding distinct functional domains (signal peptide, each Ig domain, mucin/IgA domain, transmembrane/cytoplasmic), and an alternatively spliced variant lacking the mucin/IgA exon 4 exists; the 5' flanking region contains tandem NF-kB sites, AP-1, AP-2 binding sites, and an estrogen response element.\",\n      \"method\": \"Genomic cloning, RT-PCR, sequencing, chromosomal mapping, 5' promoter analysis\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genomic characterization with functional promoter element identification; single study\",\n      \"pmids\": [\"7650378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Site-directed mutagenesis identified the LDT sequence in the CD loop of MAdCAM-1's first Ig domain as a critical binding motif for alpha 4 beta 7 integrin adhesion and cell activation.\",\n      \"method\": \"Site-directed mutagenesis of MAdCAM-1, cell adhesion assays\",\n      \"journal\": \"Immunologic research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis approach; single study, limited methodological detail in abstract\",\n      \"pmids\": [\"9379078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Alpha 4 integrin binding specificity for MAdCAM-1 versus VCAM-1 is determined not only by the critical aspartate in the CD loop, but also by accessory binding sites including an Ig domain 2 region; VCAM-1/MAdCAM-1 chimeras showed that the MAdCAM-1 adhesion motif in the context of VCAM-1 supports alpha 4 beta 1 binding, but the VCAM-1 motif in MAdCAM-1 context does not, implicating flanking structural determinants.\",\n      \"method\": \"VCAM-1/MAdCAM-1 chimera construction, recombinant protein cell adhesion assays, site-directed mutagenesis of VCAM-1\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic chimera and mutagenesis approach with comprehensive mutant panel; identifies molecular basis of integrin selectivity\",\n      \"pmids\": [\"9235944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Beta 7 integrin residues 46-386 specify alpha 4 beta 7 binding to MAdCAM-1; a MIDAS-like domain (residues 176-250) is critical for MAdCAM-1 and E-cadherin adhesion, mapped by seven blocking antibodies; residues 46-149 contain a Mn2+-dependent activating epitope that promotes MAdCAM-1 binding.\",\n      \"method\": \"Beta 7/beta 1 chimeras, human/mouse/rat chimeric beta 7 subunits, antibody epitope mapping, adhesion assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — systematic chimera analysis with comprehensive antibody panel; defines beta 7 structural determinants for MAdCAM-1 recognition\",\n      \"pmids\": [\"9233649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Crystal structure of human MAdCAM-1 Ig domains 1 and 2 at 2.2 Å resolution reveals two integrin-recognition motifs: Asp42 in the CD loop of domain 1 (the key integrin-binding residue, stabilized by buried Arg70) and an unusual negatively charged beta ribbon extending from the D and E strands of domain 2, both on the same face; architectural differences in CD loops between MAdCAM-1 and VCAM-1 cause an 8 Å shift in the critical aspartate position.\",\n      \"method\": \"X-ray crystallography at 2.2 Å resolution, structural comparison\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure with functional interpretation; landmark structural paper\",\n      \"pmids\": [\"9655832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"MAdCAM-1 costimulates T cell proliferation exclusively through integrin alpha 4 beta 7 (not alpha 4 beta 1), whereas VCAM-1 and CS-1 peptide costimulate exclusively through alpha 4 beta 1; MAdCAM-1-Fc can synergize with and induce hyperresponsiveness to B7-2; costimulation occurs even when MAdCAM-1 is spatially distant from anti-CD3 ('remote' costimulation).\",\n      \"method\": \"T cell proliferation assays with immobilized Fc chimeras, blocking antibodies to specific integrin chains\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean functional assay with integrin-specific blocking; single study\",\n      \"pmids\": [\"9842903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Secondary lymphoid-tissue chemokine (SLC/CCL21) immobilized on substrate rapidly activates alpha 4 beta 7-mediated lymphocyte adhesion to MAdCAM-1 under flow conditions through a pertussis toxin-sensitive (Gi-coupled) pathway; this effect is specific to SLC among CC chemokines tested.\",\n      \"method\": \"Flow chamber adhesion assays, pertussis toxin inhibition, blocking antibodies\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — flow-based adhesion assay with pharmacological dissection; single study\",\n      \"pmids\": [\"9670974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Transcription factor NKX2.3 directly activates MAdCAM-1 transcription; NKX2.3-deficient mice lack MAdCAM-1 expression in mucosa-associated lymphoid tissue and spleen, resulting in failure of lymphocyte migration and homing to correct compartments.\",\n      \"method\": \"Gene knockout (NKX2.3-/-) mice, immunohistochemistry, RT-PCR, transcriptional activation assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic knockout combined with transcriptional activation evidence; replicated by second study (Wang CC et al., 2000)\",\n      \"pmids\": [\"10790368\", \"10926756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"TNF-alpha induces MAdCAM-1 mRNA and protein in endothelial cells via tyrosine kinase, p42/44 MAPK, p38 MAPK, and NF-kB/PARP-dependent pathways; MEK-1/2 is activated by TNF-alpha within minutes and is dependent on TK and p42/44 MAPKs; MAdCAM-1 is frequently distributed to endothelial junctions both in vitro and in vivo.\",\n      \"method\": \"RT-PCR, Western blotting, pharmacological kinase inhibitors, immunofluorescence in endothelial cell lines (bEND.3 and SVEC)\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic pharmacological dissection of signaling pathways in endothelial cells; single study with multiple inhibitors\",\n      \"pmids\": [\"11546645\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"MAdCAM-1 expressed on inflamed hepatic portal vein/sinusoidal endothelium in autoimmune liver disease is functionally active, supporting alpha 4 beta 7+ lymphocyte adhesion (inhibited by anti-MAdCAM-1, anti-alpha 4 beta 7, anti-alpha 4 antibodies) and rolling under flow conditions.\",\n      \"method\": \"Modified Stamper-Woodruff binding assays, flow-based adhesion assays, blocking antibodies on human tissue sections\",\n      \"journal\": \"Hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional adhesion assays on human diseased tissue with multiple blocking antibodies; single study\",\n      \"pmids\": [\"11343233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"MAdCAM-1, VCAM-1, and ICAM-1 are expressed on choroid plexus epithelium (not endothelium) constitutively (ICAM-1, VCAM-1) or de novo during EAE (MAdCAM-1); these epithelial CAMs are locally synthesized and mediate lymphocyte binding via LFA-1 and alpha 4 integrin in Stamper-Woodruff assays, implicating the blood-CSF barrier epithelium in CNS immunosurveillance.\",\n      \"method\": \"Immunohistochemistry, in situ hybridization, cytokine stimulation of primary choroid plexus epithelial cells, Stamper-Woodruff binding assays\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods (ISH, IHC, functional binding assays) in EAE model; single study\",\n      \"pmids\": [\"8669469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"A revised crystal structure of human MAdCAM-1 Ig domains 1 and 2 shows one edge strand relocated to the opposite sheet compared with the first structure, altering the conformation of key integrin-binding residues; MAdCAM-1 forms dimers within the crystal lattice, suggesting oligomerization may influence biological function.\",\n      \"method\": \"X-ray crystallography (second crystal form), structural comparison\",\n      \"journal\": \"Acta crystallographica. Section D, Biological crystallography\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure, but represents a reanalysis/revision of prior structure; single study with limited functional validation\",\n      \"pmids\": [\"11807247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Immobilized CCL25 and CCL28 specifically trigger alpha 4 beta 7-dependent lymphocyte arrest on MAdCAM-1 under shear flow without affecting adhesion to VCAM-1; alpha 4 beta 7/MAdCAM-1 and alpha 4 beta 1/VCAM-1 operate as independent adhesion pathways; CCL21 and CXCL12 trigger a motile phenotype (lamellipodia/uropod) after arrest on MAdCAM-1.\",\n      \"method\": \"Flow-based adhesion assays, integrin-specific blocking antibodies, immobilized chemokines\",\n      \"journal\": \"American journal of physiology. Gastrointestinal and liver physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic flow assay with pharmacological and antibody dissection; single study\",\n      \"pmids\": [\"18308860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"GlcNAc6ST-1 preferentially utilizes MAdCAM-1 protein as a scaffold for GlcNAc-6-O-sulfation in L-selectin ligand carbohydrate biosynthesis; co-localization of MAdCAM-1 and L-selectin ligand carbohydrates (MECA-79 epitope) at luminal surface of HEV-like vessels was demonstrated, and UC disease activity correlates with GlcNAc6ST-1-mediated decoration rather than MAdCAM-1 protein levels per se.\",\n      \"method\": \"RT-PCR, immunofluorescence, FACS, Western blotting of CHO/Lec2 transfectants co-expressing MAdCAM-1 with GlcNAc6ST enzymes, immunohistochemistry\",\n      \"journal\": \"Inflammatory bowel diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — direct biochemical demonstration of enzymatic modification of MAdCAM-1 in transfected cells; single study\",\n      \"pmids\": [\"19067429\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The CC' loop of MAdCAM-1 Ig domain 1 (including Asp-42) is indispensable for binding both low- and high-affinity alpha 4 beta 7; the DE loop of domain 2 is required for binding to inactive and SDF-1alpha/talin-activated alpha 4 beta 7 but is less critical for Mn2+-activated alpha 4 beta 7, indicating distinct conformational requirements for MAdCAM-1 binding to different integrin activation states.\",\n      \"method\": \"Site-directed mutagenesis of MAdCAM-1 CC' and DE loops, cell adhesion assays with Mn2+- or chemokine/talin-activated alpha 4 beta 7\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis combined with multiple integrin activation conditions; single study\",\n      \"pmids\": [\"21296888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Alpha 4 beta 7 on hematopoietic progenitor cells (HPCs) mediates tethering and rolling on MAdCAM-1 in bone marrow (demonstrated by intravital microscopy); blocking MAdCAM-1 significantly reduces HPC homing after bone marrow transplantation, contributing to approximately half of all alpha 4 integrin-mediated homing activity.\",\n      \"method\": \"Flow cytometry, CXCL12-stimulated adhesion to immobilized MAdCAM-1, BM intravital microscopy, homing assays with blocking antibodies\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods (intravital microscopy, adhesion assays, in vivo homing); single study\",\n      \"pmids\": [\"15161666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Angiotensin II type 1 receptor (AT1R) regulates TNF-alpha-induced MAdCAM-1 expression via NF-kB nuclear translocation (but not p38 MAPK or IkB phosphorylation); AT1R-deficient mice show reduced MAdCAM-1 expression and attenuated DSS-induced colitis.\",\n      \"method\": \"AT1R blocker treatment and AT1R-/- mice, Western blotting, NF-kB translocation assays, DSS colitis model\",\n      \"journal\": \"American journal of physiology. Gastrointestinal and liver physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout combined with pharmacological inhibition and mechanistic assays; single study\",\n      \"pmids\": [\"19940029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MAdCAM-1 mediates intestinal localization of dendritic cells (conventional DCs and plasmacytoid DCs) via beta 7 integrin; MAdCAM-1-deficient and beta 7 integrin-deficient mice both show reduced CD11c+ cells and plasmacytoid DCs in gut epithelium, and reduced migration efficiency of pDC and cDC precursors into the intraepithelial compartment.\",\n      \"method\": \"MAdCAM-1 knockout mice, beta 7 integrin knockout mice, flow cytometry, migration assays\",\n      \"journal\": \"Clinical immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — parallel knockout mouse models with defined cellular phenotype; single study\",\n      \"pmids\": [\"25464027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Beta 7 integrin on hematopoietic stem cells (HSCs) interacts with MAdCAM-1 on bone marrow endothelial cells to promote HSC homing and engraftment; lethal irradiation induces MAdCAM-1 expression on BM endothelial cells; blocking MAdCAM-1 reduces HSC homing and impairs recipient survival; beta 7 KO HSCs have reduced CXCR4 expression and impaired migration.\",\n      \"method\": \"Flow cytometry, quantitative RT-PCR, in vivo homing assays, BM transplantation with blocking antibodies, beta 7 KO mice\",\n      \"journal\": \"Stem cells and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo homing assays plus genetic knockout; single study\",\n      \"pmids\": [\"26422691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MAdCAM-1-expressing lymphoid stromal cells in lymph nodes are among the first cells to respond to immunization, proliferating and upregulating podoplanin and cell adhesion molecules; this response is abrogated in aged mice; TLR4 activation with adjuvants directly stimulates MAdCAM-1+ stromal cells (shown by bone marrow chimeras) and improves the germinal center response in both young and aged mice.\",\n      \"method\": \"Heterochronic parabiosis, mouse immunization, bone marrow chimeras, flow cytometry of MAdCAM-1+ stromal cells\",\n      \"journal\": \"Science immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — heterochronic parabiosis and BM chimera experiments with defined cellular readouts; single study\",\n      \"pmids\": [\"35522725\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MAdCAM-1 promotes steatohepatitis development: MAdCAM-1-deficient mice show reduced hepatic inflammation, enhanced anti-oxidative stress (Nrf2, HO-1 upregulation), increased regulatory T cells and anti-inflammatory macrophages, and are protected from fibrosis initiation in high fat diet and methionine-choline-deficient diet models.\",\n      \"method\": \"MAdCAM-1 knockout mice, beta 7 integrin knockout mice, high fat diet / MCD diet models, histomorphology, flow cytometry, dihydroethidium staining\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — parallel knockout mouse models with multiple mechanistic readouts; single study\",\n      \"pmids\": [\"28192190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"LPAM-1 (alpha 4 beta 7) binds to MAdCAM-1 and VCAM-1 via overlapping binding sites that overlap with the RGD recognition site; fibrinogen at physiological concentrations partially blocks TK-1 cell binding to MAdCAM-1, suggesting endogenous RGD-containing vascular proteins can compete with MAdCAM-1.\",\n      \"method\": \"Cell adhesion assays with RGD-containing peptides/polymers, fibrinogen competition, blocking antibodies\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — competition adhesion assays; single study\",\n      \"pmids\": [\"9541595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In utero and during early childhood, MAdCAM-1 is widely expressed (not restricted to mucosal sites) and functionally governs lymphocyte adhesion to both gut and peripheral lymph node vessels via alpha 4 beta 7 integrin; after birth, MAdCAM-1 expression gradually becomes mucosal-restricted as PNAd/L-selectin interactions take over peripheral node adhesion.\",\n      \"method\": \"Immunostaining of human fetal and pediatric tissues, in vitro binding assays with blocking antibodies on tissue sections\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional binding assays on human tissues across developmental stages; single study\",\n      \"pmids\": [\"11606499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Exogenous NO donors (DETA-NO, SperNO) inhibit TNF-alpha-stimulated MAdCAM-1 expression in endothelial cells and reduce alpha 4 beta 7-dependent lymphocyte adhesion; inhibition of endogenous NO production (L-NAME, 1400W) does not induce or potentiate TNF-alpha-regulated MAdCAM-1 expression, distinguishing exogenous from endogenous NO regulation.\",\n      \"method\": \"Western blotting of MAdCAM-1 after NO donor/inhibitor pre-treatment, lymphocyte adhesion assays\",\n      \"journal\": \"BMC gastroenterology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — pharmacological study in cell line; single study, limited mechanistic depth\",\n      \"pmids\": [\"11481030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"P-selectin and MAdCAM-1 are co-expressed on maternal vessels during placenta development; long-term in vivo MAdCAM-1 blockade reduces recruitment of alpha 4 beta 7+ monocyte-like cells to the decidua, and absence of these cells is associated with reduced uterine NK cell numbers.\",\n      \"method\": \"In vivo antibody blockade, knockout mouse strains lacking specific adhesion receptors, immunohistochemistry\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo long-term blockade plus genetic models with defined cellular readouts; single study\",\n      \"pmids\": [\"15484189\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAdCAM-1 is an endothelial immunoglobulin superfamily adhesion molecule whose two N-terminal Ig domains (with critical Asp42 in the CD loop and an accessory DE-loop beta ribbon) bind preferentially to integrin alpha 4 beta 7 on lymphocytes and other leukocytes to mediate tethering, rolling, and firm adhesion at mucosal and inflamed tissues; its mucin-like domain, when decorated by GlcNAc6ST-1-mediated sialylated carbohydrates, additionally acts as a facultative L-selectin ligand; expression is transcriptionally controlled by NF-kB (downstream of TNF-alpha via MAPK and AT1R pathways) and by the homeodomain factor NKX2.3, while exogenous NO and IL-10 suppress its induction; the alpha 4 beta 7–MAdCAM-1 axis directs lymphocyte, dendritic cell, and hematopoietic progenitor homing to gut-associated lymphoid tissues, bone marrow, and inflamed mucosal sites, and its blockade reduces intestinal inflammation in multiple animal models.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MAdCAM-1 is an endothelial immunoglobulin superfamily adhesion molecule that directs tissue-selective lymphocyte, dendritic cell, and hematopoietic progenitor homing to gut-associated lymphoid tissues and bone marrow through its role as the dominant ligand for integrin α4β7. Its two N-terminal Ig domains present a critical Asp42 residue in the CD loop of domain 1 and an accessory negatively charged β-ribbon in the DE loop of domain 2, which together form a bipartite α4β7-binding surface whose engagement supports tethering, rolling, and firm adhesion under shear flow; the mucin-like domain, when decorated with GlcNAc6ST-1-dependent sulfated sialyl carbohydrates, additionally serves as a facultative L-selectin ligand [PMID:7687523, PMID:9655832, PMID:7505053, PMID:19067429]. MAdCAM-1 transcription is driven by NF-κB (activated downstream of TNF-α via MAPK and AT1R signaling) and the homeodomain factor NKX2.3, whose genetic ablation eliminates mucosal MAdCAM-1 expression and disrupts lymphocyte compartmentalization [PMID:10790368, PMID:11546645, PMID:19940029]. Chemokines CCL25, CCL28, and CCL21 presented on the endothelial surface rapidly trigger α4β7-dependent arrest on MAdCAM-1 through Gi-coupled signaling, and blockade of the α4β7–MAdCAM-1 axis reduces intestinal inflammation, hepatic steatohepatitis, and impairs hematopoietic stem cell engraftment in bone marrow transplantation models [PMID:18308860, PMID:9670974, PMID:28192190, PMID:26422691].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Identification of α4β7 integrin as the specific lymphocyte receptor for MAdCAM-1 established the molecular basis for mucosal-selective lymphocyte adhesion, resolving how MAdCAM-1 functions distinctly from VCAM-1.\",\n      \"evidence\": \"Cell adhesion assays with purified MAdCAM-1, blocking antibodies against α4, β7, β2 chains, and Mn2+ activation using lymphoma cell lines\",\n      \"pmids\": [\"7687523\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of α4β7 versus α4β1 selectivity not yet defined\", \"In vivo relevance of preferential binding not demonstrated\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Molecular cloning and biochemical characterization revealed MAdCAM-1 as a dual-function molecule — its Ig domains bind integrins while its mucin domain presents carbohydrates for L-selectin, explaining how a single endothelial molecule can mediate both selectin-dependent rolling and integrin-dependent arrest.\",\n      \"evidence\": \"cDNA cloning with COS cell expression and binding assays; parallel shear-flow adhesion assays with L-selectin transfectants and N-glycanase-treated MAdCAM-1 purified from mesenteric lymph nodes\",\n      \"pmids\": [\"8502297\", \"7505053\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Carbohydrate modifications responsible for L-selectin binding not molecularly defined\", \"In vivo contribution of mucin domain versus Ig domains to homing not separated\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Genomic characterization revealed tandem NF-κB sites in the MAdCAM-1 promoter, providing the first mechanistic link between inflammatory signaling and MAdCAM-1 transcriptional induction.\",\n      \"evidence\": \"Genomic cloning, sequencing, and 5′ promoter analysis of MAdCAM-1 gene (5 exons, chromosome 10)\",\n      \"pmids\": [\"7650378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NF-κB sites not yet validated by reporter or ChIP assays\", \"Alternative splicing functional consequences unknown\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Cloning of human MAdCAM-1 confirmed conservation of α4β7 binding via two N-terminal Ig domains and established mucosal-restricted expression, while showing loss of the IgA-like third domain — demonstrating species-specific structural variation.\",\n      \"evidence\": \"Functional expression cloning from macaque/human libraries, adhesion assays, RT-PCR tissue panel\",\n      \"pmids\": [\"8609404\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of missing IgA domain in humans not determined\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Systematic mutagenesis and chimera studies defined the bipartite integrin-binding surface: the LDT/Asp42 motif in the CD loop of Ig domain 1 is essential, while flanking structural context (including Ig domain 2) determines α4β7 versus α4β1 selectivity.\",\n      \"evidence\": \"Site-directed mutagenesis, VCAM-1/MAdCAM-1 chimera construction, and cell adhesion assays; parallel β7/β1 chimera mapping of integrin MIDAS-like domain\",\n      \"pmids\": [\"9379078\", \"9235944\", \"9233649\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution view of integrin–MAdCAM-1 interface not yet available\", \"Role of each Ig domain in activation-state-dependent binding not dissected\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"The crystal structure of MAdCAM-1 Ig domains 1–2 at 2.2 Å resolution revealed how Asp42 is stabilized by buried Arg70 and identified the unusual DE-loop β-ribbon of domain 2 as a second integrin-contact surface, explaining mutagenesis data and the 8 Å displacement of the critical aspartate relative to VCAM-1.\",\n      \"evidence\": \"X-ray crystallography at 2.2 Å resolution with structural comparison to VCAM-1\",\n      \"pmids\": [\"9655832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No co-crystal with α4β7; exact integrin–ligand interface still modeled\", \"Revised crystal form later raised questions about edge-strand assignment (PMID:11807247)\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstration that MAdCAM-1 costimulates T cell proliferation exclusively through α4β7 (not α4β1) and that chemokine CCL21 rapidly triggers α4β7-dependent arrest on MAdCAM-1 under flow established MAdCAM-1 as an active participant in lymphocyte activation and chemokine-directed adhesion cascades.\",\n      \"evidence\": \"T cell proliferation assays with immobilized Fc chimeras and blocking antibodies; flow chamber adhesion assays with pertussis toxin inhibition\",\n      \"pmids\": [\"9842903\", \"9670974\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Costimulatory signaling pathway downstream of α4β7 not characterized\", \"Range of chemokines capable of triggering MAdCAM-1 arrest incompletely surveyed\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Genetic ablation of NKX2.3 eliminated MAdCAM-1 expression in mucosal lymphoid tissue and disrupted lymphocyte compartmentalization, establishing NKX2.3 as a master transcriptional regulator of tissue-selective MAdCAM-1 expression.\",\n      \"evidence\": \"NKX2.3 knockout mice, immunohistochemistry, RT-PCR, transcriptional activation assays\",\n      \"pmids\": [\"10790368\", \"10926756\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NKX2.3 directly binds the MAdCAM-1 promoter (ChIP) not shown\", \"Relationship between NKX2.3 and NF-κB in MAdCAM-1 regulation not addressed\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"TNF-α–induced MAdCAM-1 expression was shown to require convergent MAPK and NF-κB/PARP signaling in endothelial cells, and MAdCAM-1 was found to localize to endothelial junctions — connecting inflammatory cytokine signaling to adhesion molecule positioning for leukocyte transmigration.\",\n      \"evidence\": \"RT-PCR, Western blotting, pharmacological kinase inhibitors in bEND.3 and SVEC endothelial cells, immunofluorescence\",\n      \"pmids\": [\"11546645\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PARP role in NF-κB-dependent MAdCAM-1 transcription not mechanistically detailed\", \"Junction localization functional consequences not tested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"MAdCAM-1 expression during fetal life is widespread rather than mucosal-restricted, with postnatal restriction occurring as PNAd/L-selectin pathways replace α4β7/MAdCAM-1 in peripheral lymph nodes — redefining MAdCAM-1 as a developmentally regulated pan-lymphoid adhesion molecule.\",\n      \"evidence\": \"Immunostaining and functional binding assays on human fetal and pediatric tissues with blocking antibodies\",\n      \"pmids\": [\"11606499\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signals driving postnatal downregulation of MAdCAM-1 in peripheral nodes not identified\", \"Functional consequences of fetal widespread expression not tested in vivo\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"α4β7/MAdCAM-1 interaction was shown to mediate hematopoietic progenitor cell tethering and rolling in bone marrow by intravital microscopy, extending MAdCAM-1 function beyond mucosal lymphocyte homing to hematopoietic stem cell engraftment.\",\n      \"evidence\": \"Intravital microscopy of bone marrow, in vivo homing assays with MAdCAM-1-blocking antibodies, CXCL12-stimulated adhesion assays\",\n      \"pmids\": [\"15161666\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of MAdCAM-1 versus VCAM-1 in BM homing not fully quantified\", \"Whether MAdCAM-1 is constitutive or induced on BM endothelium under homeostasis unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Two advances refined MAdCAM-1 regulation and function: GlcNAc6ST-1 was identified as the sulfotransferase that preferentially modifies MAdCAM-1 to generate L-selectin ligand carbohydrates, and AT1R was shown to regulate TNF-α-induced MAdCAM-1 expression via NF-κB nuclear translocation, linking the renin-angiotensin system to mucosal inflammation.\",\n      \"evidence\": \"Transfection of CHO cells co-expressing MAdCAM-1 with GlcNAc6ST enzymes, FACS, Western blotting; AT1R-/- mice and pharmacological blockade in DSS colitis model\",\n      \"pmids\": [\"19067429\", \"19940029\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether AT1R directly activates NF-κB or acts through intermediate kinases not resolved\", \"In vivo contribution of GlcNAc6ST-1-modified MAdCAM-1 to L-selectin-dependent rolling not tested genetically\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Mutagenesis of the CC' and DE loops showed that MAdCAM-1 engages different integrin activation states through distinct structural elements — the CC' loop/Asp42 is universally required, while the DE loop β-ribbon of domain 2 is dispensable for fully activated (Mn2+) but essential for physiologically activated α4β7.\",\n      \"evidence\": \"Site-directed mutagenesis of MAdCAM-1 CC' and DE loops, adhesion assays with Mn2+-, chemokine-, and talin-activated α4β7\",\n      \"pmids\": [\"21296888\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No co-crystal structure of MAdCAM-1 with α4β7 in any activation state\", \"How talin-induced versus Mn2+-induced conformational changes alter the integrin footprint on MAdCAM-1 not structurally resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"MAdCAM-1/β7 axis was shown to govern intestinal localization of dendritic cells (both conventional and plasmacytoid), broadening MAdCAM-1's functional role beyond lymphocyte homing to innate immune cell positioning in the gut.\",\n      \"evidence\": \"MAdCAM-1 knockout and β7 integrin knockout mice, flow cytometry, migration assays\",\n      \"pmids\": [\"25464027\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific integrin heterodimer on DCs mediating MAdCAM-1 binding not identified\", \"Functional consequence of reduced gut DCs on mucosal immunity not assessed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"MAdCAM-1 deficiency protected mice from diet-induced steatohepatitis by shifting immune balance toward regulatory T cells and anti-inflammatory macrophages, establishing MAdCAM-1 as a driver of hepatic inflammatory recruitment beyond its classical mucosal role.\",\n      \"evidence\": \"MAdCAM-1 and β7 knockout mice on high-fat and MCD diets, histomorphology, flow cytometry, oxidative stress markers\",\n      \"pmids\": [\"28192190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether hepatic MAdCAM-1 is endothelial or stromal in origin not determined\", \"Mechanism linking MAdCAM-1 to Nrf2/HO-1 upregulation not elucidated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"MAdCAM-1-expressing lymph node stromal cells were identified as early responders to immunization, and their age-dependent decline was shown to impair germinal center responses — revealing a non-endothelial, stromal role for MAdCAM-1+ cells in adaptive immunity.\",\n      \"evidence\": \"Heterochronic parabiosis, mouse immunization, bone marrow chimeras, flow cytometry\",\n      \"pmids\": [\"35522725\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MAdCAM-1 itself signals in stromal cells or merely marks them is unknown\", \"TLR4-dependent mechanism of stromal cell activation not molecularly defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A co-crystal structure of MAdCAM-1 bound to α4β7 integrin in physiological activation states is still lacking, and the signaling pathways downstream of MAdCAM-1 engagement in both endothelial and stromal cells remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No atomic-resolution α4β7–MAdCAM-1 complex structure\", \"Intracellular signaling triggered by MAdCAM-1 ligation in endothelial cells not characterized\", \"How MAdCAM-1+ stromal cells contribute to germinal center formation mechanistically is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 1, 2, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 3, 12]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [1, 17]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1, 11, 21]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [0, 2, 6, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ITGA4\",\n      \"ITGB7\",\n      \"SELL\",\n      \"NKX2-3\",\n      \"CHST2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}