{"gene":"FUT9","run_date":"2026-06-09T23:54:44","timeline":{"discoveries":[{"year":1999,"finding":"Human FUT9 (Fuc-TIX) encodes an α1,3-fucosyltransferase with unique cation independence: unlike FUT4 and FUT6, hFuc-TIX activity is not activated by Mn2+ or Co2+. The enzyme is highly conserved between human and mouse, indicating strong evolutionary selective pressure.","method":"Molecular cloning, enzymatic characterization in vitro with cation supplementation assays","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic characterization in a single study with no mutagenesis or structural validation","pmids":["10386598"],"is_preprint":false},{"year":2000,"finding":"Embryonic FUT9 encodes an α1,3-fucosyltransferase with substrate specificity similar to FUT4, except FUT9 does not efficiently utilize the lac-di-NAc acceptor. Like FUT4, the embryonic FUT9 enzyme is N-ethylmaleimide and heat resistant.","method":"cDNA cloning from embryonic libraries, in vitro substrate specificity and kinetics assays, enzymatic inhibitor studies","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic characterization with acceptor specificity and inhibitor assays, single lab","pmids":["10929005"],"is_preprint":false},{"year":2000,"finding":"Rat Fuc-TIX (rFuc-TIX) shows similar activity to rFuc-TIV on oligosaccharide acceptors but strikingly higher activity on lipid acceptors, suggesting FUT9 has a greater role than FUT4 in synthesis of CD15 glycolipids in brain.","method":"cDNA cloning, in vitro enzymatic activity comparison on oligosaccharide and lipid acceptors","journal":"Journal of neuroscience research","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — direct in vitro enzymatic comparison, single lab, single method","pmids":["11020213"],"is_preprint":false},{"year":2003,"finding":"Fut9 is the primary α1,3-fucosyltransferase responsible for Lewis X (Lex) synthesis in brain: recombinant Fut9 exhibited >10-fold higher activity on oligosaccharide acceptors and >100-fold higher activity on glycolipid acceptors compared to Fut4. Fut9 transcript was 15–100× more abundant than Fut4 in cerebrum and cerebellum at multiple developmental stages, and brain homogenate α1,3-FucT activity profiles matched Fut9, not Fut4.","method":"Recombinant enzyme activity assay (in vitro), RT-PCR quantification, brain homogenate enzymatic activity profiling, immunohistochemistry","journal":"Glycobiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — recombinant enzyme reconstitution with quantitative kinetics plus independent mRNA and tissue activity profiling, multiple orthogonal methods in one study","pmids":["12626397"],"is_preprint":false},{"year":2004,"finding":"Fut9 is the key enzyme for SSEA-1 (Lewis X) biosynthesis in mouse embryos and primordial germ cells in vivo: Fut9-knockout mice show complete absence of SSEA-1 in early embryos and primordial germ cells, yet develop normally and are fertile, demonstrating SSEA-1 is dispensable for embryogenesis.","method":"Genetic knockout (Fut9-/- mice), immunohistochemical analysis of SSEA-1 expression, fertility and developmental phenotyping","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with specific immunohistochemical readout, replicated findings consistent with in vitro enzyme data from prior studies","pmids":["15121843"],"is_preprint":false},{"year":2012,"finding":"FUT9 contributes to human E-selectin ligand biosynthesis in leukocytes: FUT9 knockdown in HL-60 cells reduced E-selectin-mediated rolling by 50–60%, and triple knockdown of FUT4/FUT7/FUT9 reduced it by ~85%. Gain-of-function experiments confirmed all three α1,3-fucosyltransferases (FUT4, FUT7, FUT9) can confer E-selectin-mediated rolling in HEK293T cells. FUT9 plays a species-specific role in human (but not mouse) E-selectin ligand synthesis.","method":"Lentiviral shRNA knockdown in HL-60 cells, gain-of-function overexpression in HEK293T cells, cell adhesion assay under hydrodynamic shear on selectin substrates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal loss-of-function and gain-of-function experiments with defined cellular phenotypic readout, multiple cell systems and selectin substrates","pmids":["23192350"],"is_preprint":false},{"year":2015,"finding":"Fut9 is responsible for the Lewis X (Lex) modification on N-glycans of kidney glycoproteins in vivo: glycoproteomic analysis of Fut9 knockout versus wild-type mouse kidney showed loss of terminal fucose (Lex) from 21 of 24 Lex-carrying glycoproteins, demonstrating widespread rather than protein-specific Lex synthesis by Fut9.","method":"Lectin (AAL) affinity chromatography, mass spectrometry-based site-specific N-glycomics of wild-type vs. Fut9 knockout mouse kidney","journal":"Journal of proteome research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — comparative glycoproteomics in knockout vs. wild-type with site-specific MS, multiple glycoproteins identified, single lab","pmids":["26244810"],"is_preprint":false},{"year":2017,"finding":"FUT9 catalyzes biosynthesis of Ley glycolipids and plays a complex role in colorectal cancer: FUT9 knockdown enhances proliferation and migration in monolayer culture but suppresses tumorsphere expansion and xenograft tumor growth. FUT9 silencing decreases CD44 (colorectal cancer TIC marker) and OCT4 transcription factor levels, linking FUT9 enzymatic activity to cancer stem cell maintenance.","method":"shRNA knockdown, xenograft mouse model, tumorsphere assay, Western blot/flow cytometry for CD44 and OCT4","journal":"Molecular systems biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — loss-of-function with in vivo xenograft and molecular marker readout, single lab, multiple assays but limited mechanistic pathway detail","pmids":["29196508"],"is_preprint":false},{"year":2020,"finding":"FUT9 drives programming of colon cancer cells toward a cancer stem cell-like state: de novo FUT9 expression in MC38 cells increased Lewis X, Sox2, ALDH, and CD44 expression, enhanced tumorsphere formation, resistance to 5-FU, and in vivo tumor growth. FUT9 knockout in human CRC cell lines impaired stem cell features. RNA-seq regulon analysis implicated major stemness gene regulatory networks downstream of FUT9.","method":"De novo FUT9 transfection in MC38 cells, FUT9 knockout in human CRC lines, RNA-seq regulon analysis, tumorsphere assay, 5-FU resistance assay, in vivo tumor growth, flow cytometry for stem cell markers","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain- and loss-of-function in multiple cell lines with multiple orthogonal readouts, single lab","pmids":["32927726"],"is_preprint":false},{"year":2022,"finding":"Fut9 is required for normal cortical and retinal neuronal development: Fut9-/- mice show reduced production of early-born (E11.5) neurons in cortical layer VI/subplate and retinal ganglion cell layer, with persistent reduction of Ctip2strong/Satb2- excitatory neurons in adult layer V/VI. Fut9-expressing cells are positive for Ctip2 and TLE4, markers of deep-layer corticothalamic projection neurons.","method":"Fut9 knockout mice, in situ hybridization, immunohistochemistry, birthdating with EdU/BrdU, in utero electroporation of GFP reporter","journal":"Neurochemical research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with multiple lineage tracing and birthdating methods, defined cellular phenotype, single lab","pmids":["35753011"],"is_preprint":false},{"year":2023,"finding":"Crystal structures of human FUT9 in complex with GDP, acceptor glycans, and a Michaelis complex (donor analog + acceptor) reveal the structural basis for Lewis X and Lewis Y antigen synthesis. Active site mutagenesis combined with kinetic analysis defined substrate specificity determinants and support an inverting catalytic mechanism. Structural comparisons with other GT10 fucosyltransferases provide evidence for modular evolution of donor- and acceptor-binding sites among mammalian GT10 members.","method":"X-ray crystallography (multiple complex structures), active site mutagenesis, kinetic analysis of mutants","journal":"Nature chemical biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures of multiple substrate complexes plus mutagenesis and kinetics in a single rigorous study; multiple orthogonal methods","pmids":["37202521"],"is_preprint":false},{"year":2024,"finding":"The transcription factor ELF4 directly transcriptionally activates FUT9: ChIP assays confirmed ELF4 binding to the FUT9 locus, and RNA-seq identified FUT9 as downstream of ELF4. ELF4-driven ESCC stemness (proliferation, migration, invasion) is mediated through FUT9 upregulation.","method":"RNA-seq, ChIP assay, functional rescue/knockdown experiments in ESCC cells, in vivo assays","journal":"Acta biochimica et biophysica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP confirms direct TF binding to FUT9 locus, functional link established, single lab","pmids":["37674363"],"is_preprint":false},{"year":2025,"finding":"hsa-miR-1246 directly targets the 3' UTR of FUT9 mRNA (confirmed by dual-luciferase reporter assay), suppressing FUT9 expression. The hsa-miR-1246/FUT9 axis regulates phosphorylation level and expression of GSK3β in NSCLC cells.","method":"Dual-luciferase reporter assay for 3' UTR targeting, miRNA mimic/inhibitor functional experiments, Western blotting for GSK3β","journal":"International journal of nanomedicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — dual-luciferase validates direct miRNA-3'UTR interaction, downstream signaling shown by Western blot, single lab","pmids":["39931532"],"is_preprint":false},{"year":2013,"finding":"Androgen differentially regulates Fut9 expression in the male mouse reproductive tract: androgen receptor binding sites (ARBSs) for Fut9 were identified in caput epididymis, and luciferase assays confirmed functional androgen-responsive regulation. Androgen downregulates Fut9 mRNA in caput epididymis, while having no effect in seminal vesicle.","method":"Mouse castration model, RT-PCR, identification of androgen receptor binding sites, luciferase reporter assay","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ARBS identified and validated by luciferase assay, in vivo castration model, single lab","pmids":["24284406"],"is_preprint":false}],"current_model":"FUT9 is an α1,3-fucosyltransferase (GT10 family) that catalyzes the transfer of fucose to synthesize Lewis X (Galβ1-4(Fucα1-3)GlcNAc) and Lewis Y antigens on glycoproteins and glycolipids; crystal structures with substrate complexes and active-site mutagenesis have defined its catalytic mechanism, substrate specificity determinants, and unique cation independence compared to paralogs. FUT9 is the dominant Lex-synthesizing enzyme in brain (outperforming FUT4 by >10-fold on oligosaccharides and >100-fold on lipid acceptors), is the sole enzyme responsible for SSEA-1 expression in mouse embryos and primordial germ cells in vivo, and plays a species-specific role in human E-selectin ligand biosynthesis in leukocytes; beyond glycan synthesis, FUT9 activity promotes a cancer stem cell phenotype in colorectal and esophageal cancer through regulation of stemness markers (CD44, OCT4, Sox2), is transcriptionally activated by ELF4 and suppressed by hsa-miR-1246 (which signals through GSK3β), and is required for normal deep-layer cortical and retinal neuron development in mice."},"narrative":{"mechanistic_narrative":"FUT9 is an α1,3-fucosyltransferase of the GT10 family that synthesizes Lewis X (and Lewis Y) antigens by transferring fucose onto the GlcNAc of terminal N-acetyllactosamine on both glycoproteins and glycolipids [PMID:12626397, PMID:37202521]. Crystal structures of FUT9 captured with GDP, acceptor glycans, and a Michaelis complex, together with active-site mutagenesis and kinetics, define its substrate specificity determinants and an inverting catalytic mechanism, and the enzyme is distinguished from paralogs FUT4/FUT6 by its cation independence [PMID:10386598, PMID:37202521]. FUT9 is the dominant Lewis X-synthesizing enzyme in brain, with >10-fold higher activity on oligosaccharides and >100-fold higher activity on glycolipid acceptors than FUT4 [PMID:12626397], and is the sole enzyme generating SSEA-1 (Lewis X) in mouse embryos and primordial germ cells in vivo, where its loss is nonetheless compatible with normal development and fertility [PMID:15121843]. It carries out widespread, rather than protein-restricted, Lewis X modification of N-glycans in vivo [PMID:26244810], contributes to human leukocyte E-selectin ligand biosynthesis [PMID:23192350], and is required for normal deep-layer cortical and retinal neuron development [PMID:35753011]. Beyond glycan synthesis, FUT9 activity promotes a cancer stem cell-like phenotype in colorectal and esophageal cancer through stemness markers including CD44, OCT4, and Sox2 [PMID:29196508, PMID:32927726], and is transcriptionally activated by ELF4 [PMID:37674363] and suppressed by hsa-miR-1246 acting through GSK3β [PMID:39931532].","teleology":[{"year":1999,"claim":"Establishing that human FUT9 is an α1,3-fucosyltransferase distinct from its paralogs answered whether it represented a separate catalytic activity, with cation independence as its defining biochemical signature.","evidence":"Molecular cloning and in vitro enzymatic assays with cation supplementation","pmids":["10386598"],"confidence":"Medium","gaps":["No structural or mutagenesis basis for cation independence at this stage","Physiological acceptor and tissue context not addressed"]},{"year":2000,"claim":"Acceptor specificity profiling sharpened how FUT9 differs functionally from FUT4, showing it shares Lewis X-type activity but cannot efficiently use lac-di-NAc acceptors.","evidence":"cDNA cloning from embryonic libraries with in vitro substrate specificity, kinetics, and inhibitor assays; orthologous comparison on oligosaccharide vs lipid acceptors in rat","pmids":["10929005","11020213"],"confidence":"Medium","gaps":["In vivo relevance of the lipid-acceptor preference not yet tested","No knockout to confirm enzyme is rate-limiting"]},{"year":2003,"claim":"Combining recombinant kinetics with tissue mRNA and activity profiling resolved which enzyme produces brain Lewis X, identifying FUT9 as dominant over FUT4 by >10-fold on glycans and >100-fold on glycolipids.","evidence":"Recombinant enzyme assays, RT-PCR quantification, and brain homogenate activity profiling","pmids":["12626397"],"confidence":"High","gaps":["Causal requirement in brain not yet shown by genetic loss","Specific glycolipid/glycoprotein targets in brain not enumerated"]},{"year":2004,"claim":"Genetic knockout established FUT9 as the sole enzyme generating SSEA-1 in vivo and, unexpectedly, that this antigen is dispensable for embryogenesis and fertility.","evidence":"Fut9-/- mice with immunohistochemistry of SSEA-1 and developmental/fertility phenotyping","pmids":["15121843"],"confidence":"High","gaps":["Functional role of Lewis X if any not revealed by overt phenotype","Compensation by other enzymes not formally excluded"]},{"year":2012,"claim":"Loss- and gain-of-function in human cells defined FUT9's contribution to E-selectin ligand synthesis in leukocytes and revealed a human-specific role not shared by mouse.","evidence":"shRNA knockdown in HL-60, overexpression in HEK293T, and selectin rolling adhesion assays under shear","pmids":["23192350"],"confidence":"High","gaps":["Identity of the FUT9-fucosylated selectin ligand proteins not defined","Basis of the human/mouse species difference unresolved"]},{"year":2013,"claim":"Identification and validation of androgen receptor binding sites placed Fut9 expression under hormonal control in a tissue-specific manner in the male reproductive tract.","evidence":"Mouse castration model, RT-PCR, ARBS identification, and luciferase reporter assays","pmids":["24284406"],"confidence":"Medium","gaps":["Downstream glycan/physiological consequence in epididymis not shown","Single lab without independent confirmation"]},{"year":2015,"claim":"Comparative glycoproteomics established that Fut9 carries out widespread, not protein-selective, Lewis X modification of N-glycans in vivo.","evidence":"AAL affinity enrichment and site-specific MS N-glycomics of wild-type vs Fut9 knockout kidney","pmids":["26244810"],"confidence":"High","gaps":["Functional consequence of kidney Lewis X loss not assessed","Restricted to one tissue"]},{"year":2020,"claim":"Reciprocal gain- and loss-of-function across colorectal cancer models connected FUT9 enzymatic activity to a cancer stem cell-like state via stemness markers and chemoresistance.","evidence":"De novo FUT9 expression and knockout in CRC lines, tumorsphere and 5-FU resistance assays, xenografts, RNA-seq regulon analysis, and marker readouts (CD44, OCT4, Sox2, ALDH)","pmids":["29196508","32927726"],"confidence":"Medium","gaps":["Glycan target(s) mediating the stemness effect not identified","Mechanistic link between fucosylation and transcriptional stemness networks unresolved"]},{"year":2023,"claim":"Multiple substrate-complex crystal structures plus mutagenesis defined the catalytic mechanism and substrate specificity determinants of FUT9 and framed modular evolution within the GT10 family.","evidence":"X-ray crystallography of GDP/acceptor/Michaelis complexes with active-site mutagenesis and kinetics","pmids":["37202521"],"confidence":"High","gaps":["Structural basis of substrate handoff on glycolipid vs glycoprotein acceptors not fully resolved","No structure with full lipid-linked acceptor"]},{"year":2024,"claim":"ChIP and functional experiments identified ELF4 as a direct transcriptional activator of FUT9, placing the enzyme downstream of a defined oncogenic transcription factor in esophageal cancer stemness.","evidence":"RNA-seq, ChIP at the FUT9 locus, and rescue/knockdown functional assays in ESCC cells with in vivo readouts","pmids":["37674363"],"confidence":"Medium","gaps":["Direct binding shown but quantitative promoter elements not mapped","Single lab"]},{"year":2025,"claim":"Dual-luciferase validation established hsa-miR-1246 as a direct repressor of FUT9 via its 3' UTR, linking FUT9 to GSK3β signaling in NSCLC.","evidence":"Dual-luciferase 3' UTR reporter, miRNA mimic/inhibitor assays, and GSK3β Western blotting","pmids":["39931532"],"confidence":"Medium","gaps":["Mechanistic chain from FUT9 fucosylation to GSK3β phosphorylation not resolved","Single lab"]},{"year":null,"claim":"It remains unresolved which specific FUT9-fucosylated glycoprotein or glycolipid substrates mediate its roles in neuronal development, E-selectin ligand function, and cancer stemness.","evidence":"No discovery in the corpus links a defined fucosylated target to these downstream phenotypes","pmids":[],"confidence":"Medium","gaps":["Causal glycan targets for each phenotype unidentified","Mechanism connecting glycan synthesis to transcriptional stemness networks unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,2,3,10]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,6,10]}],"localization":[],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,6,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[4,9]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[7,8,11,12]}],"complexes":[],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y231","full_name":"4-galactosyl-N-acetylglucosaminide 3-alpha-L-fucosyltransferase 9","aliases":["Fucosyltransferase 9","Fucosyltransferase IX","Fuc-TIX","FucT-IX","Galactoside 3-L-fucosyltransferase"],"length_aa":359,"mass_kda":42.1,"function":"Catalyzes alpha(1->3) linkage of fucosyl moiety transferred from GDP-beta-L-fucose to N-acetyl glucosamine (GlcNAc) within type 2 lactosamine (LacNAc, beta-D-Gal-(1->4)-beta-D-GlcNAc-) glycan attached to glycolipids and N- or O-linked glycoproteins. Fucosylates distal type 2 LacNAc and its fucosylated (H-type 2 LacNAc) and sialylated (sialyl-type 2 LacNAc) derivatives to form Lewis x (Lex) (CD15) and Lewis y (Ley) antigenic epitopes involved in cell adhesion and differentiation (PubMed:10386598, PubMed:10622713, PubMed:11278338, PubMed:12107078, PubMed:16282604, PubMed:17335083, PubMed:18395013, PubMed:23192350, PubMed:23263199, PubMed:29593094, PubMed:37202521). Generates Lex epitopes in the brain, presumably playing a role in the maintenance of neuronal stemness and neurite outgrowth in progenitor neural cells (By similarity) (PubMed:17335083, PubMed:23000574). Fucosylates the internal type 2 LacNAc unit of the polylactosamine chain to form VIM-2 antigen that serves as recognition epitope for SELE (PubMed:23192350). Can also modify milk oligosaccharides, in particular type 2 tetrasaccharide LNnT (PubMed:37202521)","subcellular_location":"Golgi apparatus, trans-Golgi network membrane; Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y231/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FUT9","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/FUT9","total_profiled":1310},"omim":[{"mim_id":"611162","title":"MALARIA, SUSCEPTIBILITY TO","url":"https://www.omim.org/entry/611162"},{"mim_id":"606865","title":"FUCOSYLTRANSFERASE 9; FUT9","url":"https://www.omim.org/entry/606865"},{"mim_id":"157300","title":"MIGRAINE WITH OR WITHOUT AURA, SUSCEPTIBILITY TO, 1","url":"https://www.omim.org/entry/157300"},{"mim_id":"104230","title":"FUCOSYLTRANSFERASE 4; FUT4","url":"https://www.omim.org/entry/104230"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Microtubules","reliability":"Additional"},{"location":"Cytokinetic bridge","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":16.0},{"tissue":"stomach 1","ntpm":21.8}],"url":"https://www.proteinatlas.org/search/FUT9"},"hgnc":{"alias_symbol":["Fuc-TIX"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y231","domains":[{"cath_id":"3.40.50.11660","chopping":"169-324","consensus_level":"high","plddt":96.635,"start":169,"end":324},{"cath_id":"3.40.50","chopping":"63-166_329-357","consensus_level":"high","plddt":96.0617,"start":63,"end":357}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y231","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y231-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y231-F1-predicted_aligned_error_v6.png","plddt_mean":90.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FUT9","jax_strain_url":"https://www.jax.org/strain/search?query=FUT9"},"sequence":{"accession":"Q9Y231","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y231.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y231/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y231"}},"corpus_meta":[{"pmid":"10386598","id":"PMC_10386598","title":"Alpha1,3-fucosyltransferase IX (Fuc-TIX) is very highly conserved between human and mouse; molecular cloning, characterization and tissue distribution of human Fuc-TIX.","date":"1999","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/10386598","citation_count":98,"is_preprint":false},{"pmid":"23192350","id":"PMC_23192350","title":"Silencing α1,3-fucosyltransferases in human leukocytes reveals a role for FUT9 enzyme during E-selectin-mediated cell adhesion.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23192350","citation_count":75,"is_preprint":false},{"pmid":"10929005","id":"PMC_10929005","title":"FUT4 and FUT9 genes are expressed early in human embryogenesis.","date":"2000","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/10929005","citation_count":63,"is_preprint":false},{"pmid":"12626397","id":"PMC_12626397","title":"Alpha1,3-fucosyltransferase IX (Fut9) determines Lewis X expression in brain.","date":"2003","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/12626397","citation_count":62,"is_preprint":false},{"pmid":"15121843","id":"PMC_15121843","title":"Normal embryonic and germ cell development in mice lacking alpha 1,3-fucosyltransferase IX (Fut9) which show disappearance of stage-specific embryonic antigen 1.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15121843","citation_count":53,"is_preprint":false},{"pmid":"29196508","id":"PMC_29196508","title":"An integrated computational and experimental study uncovers FUT9 as a metabolic driver of colorectal cancer.","date":"2017","source":"Molecular systems biology","url":"https://pubmed.ncbi.nlm.nih.gov/29196508","citation_count":42,"is_preprint":false},{"pmid":"26244810","id":"PMC_26244810","title":"Large-Scale Identification of N-Glycan Glycoproteins Carrying Lewis x and Site-Specific N-Glycan Alterations in Fut9 Knockout Mice.","date":"2015","source":"Journal of proteome research","url":"https://pubmed.ncbi.nlm.nih.gov/26244810","citation_count":38,"is_preprint":false},{"pmid":"32927726","id":"PMC_32927726","title":"FUT9-Driven Programming of Colon Cancer Cells towards a Stem Cell-Like State.","date":"2020","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/32927726","citation_count":25,"is_preprint":false},{"pmid":"37202521","id":"PMC_37202521","title":"Structural basis for Lewis antigen synthesis by the α1,3-fucosyltransferase FUT9.","date":"2023","source":"Nature chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/37202521","citation_count":21,"is_preprint":false},{"pmid":"11020213","id":"PMC_11020213","title":"Molecular cloning of rat alpha1,3-fucosyltransferase IX (Fuc-TIX) and comparison of the expression of Fuc-TIV and Fuc-TIX genes during rat postnatal cerebellum development.","date":"2000","source":"Journal of neuroscience research","url":"https://pubmed.ncbi.nlm.nih.gov/11020213","citation_count":16,"is_preprint":false},{"pmid":"19460885","id":"PMC_19460885","title":"A variant in the gene FUT9 is associated with susceptibility to placental malaria infection.","date":"2009","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19460885","citation_count":9,"is_preprint":false},{"pmid":"24284406","id":"PMC_24284406","title":"Different effects of androgen on the expression of Fut1, Fut2, Fut4 and Fut9 in male mouse reproductive tract.","date":"2013","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/24284406","citation_count":8,"is_preprint":false},{"pmid":"35753011","id":"PMC_35753011","title":"Fut9 Deficiency Causes Abnormal Neural Development in the Mouse Cerebral Cortex and Retina.","date":"2022","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/35753011","citation_count":8,"is_preprint":false},{"pmid":"37674363","id":"PMC_37674363","title":"ELF4 contributes to esophageal squamous cell carcinoma growth and metastasis by augmenting cancer stemness via FUT9.","date":"2024","source":"Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/37674363","citation_count":7,"is_preprint":false},{"pmid":"39931532","id":"PMC_39931532","title":"Intervening Non-Small-Cell Lung Cancer Progression by Cell Membrane Coated Platycodin D via Regulating Hsa-miR-1246/FUT9/GSK3β Pathway.","date":"2025","source":"International journal of nanomedicine","url":"https://pubmed.ncbi.nlm.nih.gov/39931532","citation_count":4,"is_preprint":false},{"pmid":"12417923","id":"PMC_12417923","title":"[Regulation by ovarian hormones of alpha 1,3-fucosyltransferase gene (FUT9) expression in human endometrium].","date":"2002","source":"Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/12417923","citation_count":4,"is_preprint":false},{"pmid":"40090531","id":"PMC_40090531","title":"Polymorphisms of FUT9 and its relationship with susceptibility towards DHAV-3 in Pekin duck.","date":"2025","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/40090531","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.02.15.638459","title":"N-Glycan Fingerprinting of the NIST monoclonal antibody (NISTmAb)","date":"2025-02-20","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.15.638459","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11189,"output_tokens":3771,"usd":0.045066,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11606,"output_tokens":3539,"usd":0.073252,"stage2_stop_reason":"end_turn"},"total_usd":0.118318,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"Human FUT9 (Fuc-TIX) encodes an α1,3-fucosyltransferase with unique cation independence: unlike FUT4 and FUT6, hFuc-TIX activity is not activated by Mn2+ or Co2+. The enzyme is highly conserved between human and mouse, indicating strong evolutionary selective pressure.\",\n      \"method\": \"Molecular cloning, enzymatic characterization in vitro with cation supplementation assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic characterization in a single study with no mutagenesis or structural validation\",\n      \"pmids\": [\"10386598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Embryonic FUT9 encodes an α1,3-fucosyltransferase with substrate specificity similar to FUT4, except FUT9 does not efficiently utilize the lac-di-NAc acceptor. Like FUT4, the embryonic FUT9 enzyme is N-ethylmaleimide and heat resistant.\",\n      \"method\": \"cDNA cloning from embryonic libraries, in vitro substrate specificity and kinetics assays, enzymatic inhibitor studies\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic characterization with acceptor specificity and inhibitor assays, single lab\",\n      \"pmids\": [\"10929005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Rat Fuc-TIX (rFuc-TIX) shows similar activity to rFuc-TIV on oligosaccharide acceptors but strikingly higher activity on lipid acceptors, suggesting FUT9 has a greater role than FUT4 in synthesis of CD15 glycolipids in brain.\",\n      \"method\": \"cDNA cloning, in vitro enzymatic activity comparison on oligosaccharide and lipid acceptors\",\n      \"journal\": \"Journal of neuroscience research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — direct in vitro enzymatic comparison, single lab, single method\",\n      \"pmids\": [\"11020213\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Fut9 is the primary α1,3-fucosyltransferase responsible for Lewis X (Lex) synthesis in brain: recombinant Fut9 exhibited >10-fold higher activity on oligosaccharide acceptors and >100-fold higher activity on glycolipid acceptors compared to Fut4. Fut9 transcript was 15–100× more abundant than Fut4 in cerebrum and cerebellum at multiple developmental stages, and brain homogenate α1,3-FucT activity profiles matched Fut9, not Fut4.\",\n      \"method\": \"Recombinant enzyme activity assay (in vitro), RT-PCR quantification, brain homogenate enzymatic activity profiling, immunohistochemistry\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — recombinant enzyme reconstitution with quantitative kinetics plus independent mRNA and tissue activity profiling, multiple orthogonal methods in one study\",\n      \"pmids\": [\"12626397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Fut9 is the key enzyme for SSEA-1 (Lewis X) biosynthesis in mouse embryos and primordial germ cells in vivo: Fut9-knockout mice show complete absence of SSEA-1 in early embryos and primordial germ cells, yet develop normally and are fertile, demonstrating SSEA-1 is dispensable for embryogenesis.\",\n      \"method\": \"Genetic knockout (Fut9-/- mice), immunohistochemical analysis of SSEA-1 expression, fertility and developmental phenotyping\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with specific immunohistochemical readout, replicated findings consistent with in vitro enzyme data from prior studies\",\n      \"pmids\": [\"15121843\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FUT9 contributes to human E-selectin ligand biosynthesis in leukocytes: FUT9 knockdown in HL-60 cells reduced E-selectin-mediated rolling by 50–60%, and triple knockdown of FUT4/FUT7/FUT9 reduced it by ~85%. Gain-of-function experiments confirmed all three α1,3-fucosyltransferases (FUT4, FUT7, FUT9) can confer E-selectin-mediated rolling in HEK293T cells. FUT9 plays a species-specific role in human (but not mouse) E-selectin ligand synthesis.\",\n      \"method\": \"Lentiviral shRNA knockdown in HL-60 cells, gain-of-function overexpression in HEK293T cells, cell adhesion assay under hydrodynamic shear on selectin substrates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal loss-of-function and gain-of-function experiments with defined cellular phenotypic readout, multiple cell systems and selectin substrates\",\n      \"pmids\": [\"23192350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Fut9 is responsible for the Lewis X (Lex) modification on N-glycans of kidney glycoproteins in vivo: glycoproteomic analysis of Fut9 knockout versus wild-type mouse kidney showed loss of terminal fucose (Lex) from 21 of 24 Lex-carrying glycoproteins, demonstrating widespread rather than protein-specific Lex synthesis by Fut9.\",\n      \"method\": \"Lectin (AAL) affinity chromatography, mass spectrometry-based site-specific N-glycomics of wild-type vs. Fut9 knockout mouse kidney\",\n      \"journal\": \"Journal of proteome research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — comparative glycoproteomics in knockout vs. wild-type with site-specific MS, multiple glycoproteins identified, single lab\",\n      \"pmids\": [\"26244810\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FUT9 catalyzes biosynthesis of Ley glycolipids and plays a complex role in colorectal cancer: FUT9 knockdown enhances proliferation and migration in monolayer culture but suppresses tumorsphere expansion and xenograft tumor growth. FUT9 silencing decreases CD44 (colorectal cancer TIC marker) and OCT4 transcription factor levels, linking FUT9 enzymatic activity to cancer stem cell maintenance.\",\n      \"method\": \"shRNA knockdown, xenograft mouse model, tumorsphere assay, Western blot/flow cytometry for CD44 and OCT4\",\n      \"journal\": \"Molecular systems biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — loss-of-function with in vivo xenograft and molecular marker readout, single lab, multiple assays but limited mechanistic pathway detail\",\n      \"pmids\": [\"29196508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FUT9 drives programming of colon cancer cells toward a cancer stem cell-like state: de novo FUT9 expression in MC38 cells increased Lewis X, Sox2, ALDH, and CD44 expression, enhanced tumorsphere formation, resistance to 5-FU, and in vivo tumor growth. FUT9 knockout in human CRC cell lines impaired stem cell features. RNA-seq regulon analysis implicated major stemness gene regulatory networks downstream of FUT9.\",\n      \"method\": \"De novo FUT9 transfection in MC38 cells, FUT9 knockout in human CRC lines, RNA-seq regulon analysis, tumorsphere assay, 5-FU resistance assay, in vivo tumor growth, flow cytometry for stem cell markers\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain- and loss-of-function in multiple cell lines with multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"32927726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Fut9 is required for normal cortical and retinal neuronal development: Fut9-/- mice show reduced production of early-born (E11.5) neurons in cortical layer VI/subplate and retinal ganglion cell layer, with persistent reduction of Ctip2strong/Satb2- excitatory neurons in adult layer V/VI. Fut9-expressing cells are positive for Ctip2 and TLE4, markers of deep-layer corticothalamic projection neurons.\",\n      \"method\": \"Fut9 knockout mice, in situ hybridization, immunohistochemistry, birthdating with EdU/BrdU, in utero electroporation of GFP reporter\",\n      \"journal\": \"Neurochemical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with multiple lineage tracing and birthdating methods, defined cellular phenotype, single lab\",\n      \"pmids\": [\"35753011\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Crystal structures of human FUT9 in complex with GDP, acceptor glycans, and a Michaelis complex (donor analog + acceptor) reveal the structural basis for Lewis X and Lewis Y antigen synthesis. Active site mutagenesis combined with kinetic analysis defined substrate specificity determinants and support an inverting catalytic mechanism. Structural comparisons with other GT10 fucosyltransferases provide evidence for modular evolution of donor- and acceptor-binding sites among mammalian GT10 members.\",\n      \"method\": \"X-ray crystallography (multiple complex structures), active site mutagenesis, kinetic analysis of mutants\",\n      \"journal\": \"Nature chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures of multiple substrate complexes plus mutagenesis and kinetics in a single rigorous study; multiple orthogonal methods\",\n      \"pmids\": [\"37202521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The transcription factor ELF4 directly transcriptionally activates FUT9: ChIP assays confirmed ELF4 binding to the FUT9 locus, and RNA-seq identified FUT9 as downstream of ELF4. ELF4-driven ESCC stemness (proliferation, migration, invasion) is mediated through FUT9 upregulation.\",\n      \"method\": \"RNA-seq, ChIP assay, functional rescue/knockdown experiments in ESCC cells, in vivo assays\",\n      \"journal\": \"Acta biochimica et biophysica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP confirms direct TF binding to FUT9 locus, functional link established, single lab\",\n      \"pmids\": [\"37674363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"hsa-miR-1246 directly targets the 3' UTR of FUT9 mRNA (confirmed by dual-luciferase reporter assay), suppressing FUT9 expression. The hsa-miR-1246/FUT9 axis regulates phosphorylation level and expression of GSK3β in NSCLC cells.\",\n      \"method\": \"Dual-luciferase reporter assay for 3' UTR targeting, miRNA mimic/inhibitor functional experiments, Western blotting for GSK3β\",\n      \"journal\": \"International journal of nanomedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — dual-luciferase validates direct miRNA-3'UTR interaction, downstream signaling shown by Western blot, single lab\",\n      \"pmids\": [\"39931532\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Androgen differentially regulates Fut9 expression in the male mouse reproductive tract: androgen receptor binding sites (ARBSs) for Fut9 were identified in caput epididymis, and luciferase assays confirmed functional androgen-responsive regulation. Androgen downregulates Fut9 mRNA in caput epididymis, while having no effect in seminal vesicle.\",\n      \"method\": \"Mouse castration model, RT-PCR, identification of androgen receptor binding sites, luciferase reporter assay\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ARBS identified and validated by luciferase assay, in vivo castration model, single lab\",\n      \"pmids\": [\"24284406\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FUT9 is an α1,3-fucosyltransferase (GT10 family) that catalyzes the transfer of fucose to synthesize Lewis X (Galβ1-4(Fucα1-3)GlcNAc) and Lewis Y antigens on glycoproteins and glycolipids; crystal structures with substrate complexes and active-site mutagenesis have defined its catalytic mechanism, substrate specificity determinants, and unique cation independence compared to paralogs. FUT9 is the dominant Lex-synthesizing enzyme in brain (outperforming FUT4 by >10-fold on oligosaccharides and >100-fold on lipid acceptors), is the sole enzyme responsible for SSEA-1 expression in mouse embryos and primordial germ cells in vivo, and plays a species-specific role in human E-selectin ligand biosynthesis in leukocytes; beyond glycan synthesis, FUT9 activity promotes a cancer stem cell phenotype in colorectal and esophageal cancer through regulation of stemness markers (CD44, OCT4, Sox2), is transcriptionally activated by ELF4 and suppressed by hsa-miR-1246 (which signals through GSK3β), and is required for normal deep-layer cortical and retinal neuron development in mice.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"FUT9 is an α1,3-fucosyltransferase of the GT10 family that synthesizes Lewis X (and Lewis Y) antigens by transferring fucose onto the GlcNAc of terminal N-acetyllactosamine on both glycoproteins and glycolipids [#3, #10]. Crystal structures of FUT9 captured with GDP, acceptor glycans, and a Michaelis complex, together with active-site mutagenesis and kinetics, define its substrate specificity determinants and an inverting catalytic mechanism, and the enzyme is distinguished from paralogs FUT4/FUT6 by its cation independence [#0, #10]. FUT9 is the dominant Lewis X-synthesizing enzyme in brain, with >10-fold higher activity on oligosaccharides and >100-fold higher activity on glycolipid acceptors than FUT4 [#3], and is the sole enzyme generating SSEA-1 (Lewis X) in mouse embryos and primordial germ cells in vivo, where its loss is nonetheless compatible with normal development and fertility [#4]. It carries out widespread, rather than protein-restricted, Lewis X modification of N-glycans in vivo [#6], contributes to human leukocyte E-selectin ligand biosynthesis [#5], and is required for normal deep-layer cortical and retinal neuron development [#9]. Beyond glycan synthesis, FUT9 activity promotes a cancer stem cell-like phenotype in colorectal and esophageal cancer through stemness markers including CD44, OCT4, and Sox2 [#7, #8], and is transcriptionally activated by ELF4 [#11] and suppressed by hsa-miR-1246 acting through GSK3β [#12].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Establishing that human FUT9 is an α1,3-fucosyltransferase distinct from its paralogs answered whether it represented a separate catalytic activity, with cation independence as its defining biochemical signature.\",\n      \"evidence\": \"Molecular cloning and in vitro enzymatic assays with cation supplementation\",\n      \"pmids\": [\"10386598\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural or mutagenesis basis for cation independence at this stage\", \"Physiological acceptor and tissue context not addressed\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Acceptor specificity profiling sharpened how FUT9 differs functionally from FUT4, showing it shares Lewis X-type activity but cannot efficiently use lac-di-NAc acceptors.\",\n      \"evidence\": \"cDNA cloning from embryonic libraries with in vitro substrate specificity, kinetics, and inhibitor assays; orthologous comparison on oligosaccharide vs lipid acceptors in rat\",\n      \"pmids\": [\"10929005\", \"11020213\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of the lipid-acceptor preference not yet tested\", \"No knockout to confirm enzyme is rate-limiting\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Combining recombinant kinetics with tissue mRNA and activity profiling resolved which enzyme produces brain Lewis X, identifying FUT9 as dominant over FUT4 by >10-fold on glycans and >100-fold on glycolipids.\",\n      \"evidence\": \"Recombinant enzyme assays, RT-PCR quantification, and brain homogenate activity profiling\",\n      \"pmids\": [\"12626397\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal requirement in brain not yet shown by genetic loss\", \"Specific glycolipid/glycoprotein targets in brain not enumerated\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Genetic knockout established FUT9 as the sole enzyme generating SSEA-1 in vivo and, unexpectedly, that this antigen is dispensable for embryogenesis and fertility.\",\n      \"evidence\": \"Fut9-/- mice with immunohistochemistry of SSEA-1 and developmental/fertility phenotyping\",\n      \"pmids\": [\"15121843\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of Lewis X if any not revealed by overt phenotype\", \"Compensation by other enzymes not formally excluded\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Loss- and gain-of-function in human cells defined FUT9's contribution to E-selectin ligand synthesis in leukocytes and revealed a human-specific role not shared by mouse.\",\n      \"evidence\": \"shRNA knockdown in HL-60, overexpression in HEK293T, and selectin rolling adhesion assays under shear\",\n      \"pmids\": [\"23192350\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the FUT9-fucosylated selectin ligand proteins not defined\", \"Basis of the human/mouse species difference unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identification and validation of androgen receptor binding sites placed Fut9 expression under hormonal control in a tissue-specific manner in the male reproductive tract.\",\n      \"evidence\": \"Mouse castration model, RT-PCR, ARBS identification, and luciferase reporter assays\",\n      \"pmids\": [\"24284406\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream glycan/physiological consequence in epididymis not shown\", \"Single lab without independent confirmation\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Comparative glycoproteomics established that Fut9 carries out widespread, not protein-selective, Lewis X modification of N-glycans in vivo.\",\n      \"evidence\": \"AAL affinity enrichment and site-specific MS N-glycomics of wild-type vs Fut9 knockout kidney\",\n      \"pmids\": [\"26244810\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of kidney Lewis X loss not assessed\", \"Restricted to one tissue\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Reciprocal gain- and loss-of-function across colorectal cancer models connected FUT9 enzymatic activity to a cancer stem cell-like state via stemness markers and chemoresistance.\",\n      \"evidence\": \"De novo FUT9 expression and knockout in CRC lines, tumorsphere and 5-FU resistance assays, xenografts, RNA-seq regulon analysis, and marker readouts (CD44, OCT4, Sox2, ALDH)\",\n      \"pmids\": [\"29196508\", \"32927726\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Glycan target(s) mediating the stemness effect not identified\", \"Mechanistic link between fucosylation and transcriptional stemness networks unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multiple substrate-complex crystal structures plus mutagenesis defined the catalytic mechanism and substrate specificity determinants of FUT9 and framed modular evolution within the GT10 family.\",\n      \"evidence\": \"X-ray crystallography of GDP/acceptor/Michaelis complexes with active-site mutagenesis and kinetics\",\n      \"pmids\": [\"37202521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of substrate handoff on glycolipid vs glycoprotein acceptors not fully resolved\", \"No structure with full lipid-linked acceptor\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"ChIP and functional experiments identified ELF4 as a direct transcriptional activator of FUT9, placing the enzyme downstream of a defined oncogenic transcription factor in esophageal cancer stemness.\",\n      \"evidence\": \"RNA-seq, ChIP at the FUT9 locus, and rescue/knockdown functional assays in ESCC cells with in vivo readouts\",\n      \"pmids\": [\"37674363\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding shown but quantitative promoter elements not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Dual-luciferase validation established hsa-miR-1246 as a direct repressor of FUT9 via its 3' UTR, linking FUT9 to GSK3β signaling in NSCLC.\",\n      \"evidence\": \"Dual-luciferase 3' UTR reporter, miRNA mimic/inhibitor assays, and GSK3β Western blotting\",\n      \"pmids\": [\"39931532\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic chain from FUT9 fucosylation to GSK3β phosphorylation not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved which specific FUT9-fucosylated glycoprotein or glycolipid substrates mediate its roles in neuronal development, E-selectin ligand function, and cancer stemness.\",\n      \"evidence\": \"No discovery in the corpus links a defined fucosylated target to these downstream phenotypes\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal glycan targets for each phenotype unidentified\", \"Mechanism connecting glycan synthesis to transcriptional stemness networks unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2, 3, 10]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 6, 10]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 6, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [4, 9]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [7, 8, 11, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":5,"faith_total":5,"faith_pct":100.0}}