{"gene":"LFNG","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2008,"finding":"LFNG encodes a fucose-specific beta1,3-N-acetylglucosaminyltransferase that modifies Notch receptors, thereby altering Notch signaling activity; this glycosylation activity is required for normal somite formation and vertebral column development.","method":"Genetic mouse and human mutation studies combined with biochemical characterization of enzymatic function","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1-2 — enzymatic function established, replicated across multiple organisms and independently confirmed","pmids":["19061953","19899223"],"is_preprint":false},{"year":2016,"finding":"LFNG protein processing and secretion are required for normal segmentation clock function; replacing the N-terminal signal sequence of LFNG with a Golgi-retention sequence (from Radical fringe) prevents secretion, increases intracellular half-life, and causes dominant somite and skeletal abnormalities distinct from Lfng loss-of-function, perturbing both transcriptional and post-transcriptional regulation of clock components including Hes7.","method":"Knock-in mouse allele (Lfng^RLFNG), in vivo gene expression analysis, cyclic gene expression assays in presomitic mesoderm","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — clean in vivo genetic model with defined molecular phenotype (Hes7 stabilization, altered clock gene expression)","pmids":["26811377"],"is_preprint":false},{"year":2013,"finding":"miR-125a-5p targets evolutionarily conserved sequences in the Lfng 3' UTR to promote transcript instability, and blocking this interaction in vivo perturbs segmentation clock activity and causes abnormal somitogenesis in chick embryos.","method":"In vivo miRNA-target blocking experiments in chick embryos, 3'UTR reporter assays, in situ hybridization of clock gene expression","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — in vivo functional validation with defined phenotypic readout and molecular mechanism","pmids":["23484856"],"is_preprint":false},{"year":2017,"finding":"Mutation of mir-125 binding sites in the mouse Lfng 3'UTR leads to persistent, non-oscillatory reporter transcript expression in the caudal presomitic mesoderm, confirming that these sites regulate transcript turnover in the segmentation clock, though mir-125a-5p itself is dispensable for mouse somitogenesis.","method":"3'UTR reporter transgenes in mouse embryos, germline mir-125a-5p knockout, in situ hybridization","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic experiment but reveals compensatory mechanisms and partial discordance with chick data","pmids":["28710840"],"is_preprint":false},{"year":2014,"finding":"The level of oscillatory Lfng expression in the presomitic mesoderm modulates the period of the segmentation clock; reduced Lfng oscillation amplitude increases the clock period, and Lfng dosage differentially affects anterior (primary body) versus posterior (secondary body) skeletal development.","method":"Allelic series of Lfng hypomorphic mouse lines, quantitative analysis of clock period and skeletal phenotypes","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean in vivo genetic allelic series with quantitative clock period measurements","pmids":["24560643"],"is_preprint":false},{"year":2022,"finding":"LFNG glycosylates EGF-repeats of DLL1 and DLL3 ligands (in addition to Notch receptors), and in signal-sending cells co-expressing DLL1 and NOTCH1, DLL3 can potentiate signal-sending activity in a manner modulated by LFNG; genetic epistasis shows DLL3 loss is epistatic to LFNG loss in the segmentation clock, indicating LFNG can act in signal-sending cells to coordinate oscillatory Notch activation.","method":"Double mutant mouse genetic epistasis, mass spectrometry of glycosylated EGF repeats, cell-based Notch signaling assays with DLL1/DLL3/LFNG co-expression","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including mass spectrometry, genetic epistasis, and cell-based functional assays","pmids":["35429490"],"is_preprint":false},{"year":2018,"finding":"TGFBR2 signaling upregulates LFNG expression in colorectal cancer cells, which in turn increases N-acetyl-d-glucosamine incorporation into the Notch1 receptor without altering Notch1 protein levels, demonstrating that TGFBR2 can modulate Notch1 glycosylation via LFNG.","method":"TGFBR2-reconstituted HCT116 cells, Glyco-Gene Chip, dual radiolabeling ([3H]-GlcNAc and [35S]-methionine), immunoprecipitation of Notch1","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — direct biochemical demonstration of GlcNAc incorporation into Notch1 via LFNG in a reconstituted cell system","pmids":["27156840"],"is_preprint":false},{"year":2018,"finding":"LFNG variant p.D201N in the DxD active-site motif of the glycosyltransferase abolishes enzyme function, as confirmed by in vitro enzyme assay, and causes spondylocostal dysostosis type 3 in a compound heterozygous patient.","method":"In vitro glycosyltransferase enzyme assay, compound heterozygous patient sequencing","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro enzymatic assay with active-site mutant, single study","pmids":["30531807"],"is_preprint":false},{"year":2024,"finding":"A novel LFNG missense variant p.R360C causes loss of glycosyltransferase enzyme activity, confirmed by in vitro enzyme assay, and results in spondylocostal dysostosis.","method":"In vitro LFNG enzyme activity assay, whole exome sequencing","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 1 — direct in vitro enzymatic activity assay, single study","pmids":["38565611"],"is_preprint":false},{"year":2024,"finding":"Androgen receptor (AR) directly binds the Lfng promoter to activate its expression in Sertoli cells; androgen blockade reduces AR binding at the Lfng promoter, decreasing LFNG expression, which impairs Notch modification and reduces GDNF production required for spermatogonial stem cell self-renewal.","method":"ChIP-seq (AR binding at Lfng promoter), RNA-seq, enzalutamide androgen blockade model in Sertoli cells","journal":"Cell communication and signaling","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP-seq identifies direct AR binding at Lfng promoter with functional downstream readout","pmids":["39407201"],"is_preprint":false},{"year":2024,"finding":"Lfng expression marks a centroacinar subpopulation in the pancreas; Lfng deletion blocks tumor initiation from these cells upon oncogenic Kras and p53 deletion, and Notch3 is identified as the functional Notch receptor in this context.","method":"Lineage-specific Cre-mediated Lfng deletion in mouse PDAC models, genetic epistasis with Kras and p53 mutations","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic loss-of-function with defined cellular and molecular phenotype","pmids":["39548190"],"is_preprint":false},{"year":2014,"finding":"In Lfng-deficient triple-negative breast cancer cells with Met amplification, inhibition of Met downregulates Dll ligands and upregulates Jagged ligands, leading to differential modulation of Notch signaling; Notch inhibition (GSI) alone had no effect but synergized with Met inhibition on cell growth.","method":"Pharmacological inhibition (Met inhibitor, GSI), cell-based assays (growth, tumorsphere, colony formation, migration), ligand expression analysis","journal":"Cancer biology & therapy","confidence":"Low","confidence_rationale":"Tier 3 — cell-based pharmacological study without direct mechanistic dissection of LFNG function","pmids":["24556651"],"is_preprint":false}],"current_model":"LFNG (Lunatic Fringe) encodes a Golgi-resident fucose-specific beta1,3-N-acetylglucosaminyltransferase that modifies O-fucose residues on EGF-like repeats of Notch receptors (and Notch ligands DLL1/DLL3), thereby modulating Notch signaling activity; in the presomitic mesoderm, LFNG expression oscillates as part of the segmentation clock and its cyclic activity periodically represses Notch signaling to pace somitogenesis, with clock period sensitive to LFNG dosage and transcript turnover regulated post-transcriptionally by miR-125a-5p targeting the Lfng 3'UTR; LFNG also requires N-terminal processing and secretion for proper clock function, and loss-of-function mutations in its DxD catalytic motif abolish glycosyltransferase activity and cause spondylocostal dysostosis type 3 in humans."},"narrative":{"teleology":[{"year":2008,"claim":"Establishing that LFNG encodes a fucose-specific β1,3-N-acetylglucosaminyltransferase that glycosylates Notch receptors resolved the molecular basis by which Fringe proteins modulate Notch signaling and explained the somitogenesis defects observed in Lfng mutant mice and humans.","evidence":"Genetic studies in mouse and human combined with biochemical characterization of enzymatic specificity","pmids":["19061953","19899223"],"confidence":"High","gaps":["Whether LFNG modifies Notch ligands in addition to receptors was unknown","How LFNG protein processing and turnover contribute to clock function was unresolved","No structural model of LFNG-substrate interaction existed"]},{"year":2013,"claim":"Demonstrating that miR-125a-5p targets the Lfng 3′ UTR to destabilize its transcript in vivo revealed a post-transcriptional mechanism contributing to the oscillatory expression pattern required by the segmentation clock.","evidence":"In vivo miRNA-target blocking in chick embryos with 3′ UTR reporter assays and clock gene expression analysis","pmids":["23484856"],"confidence":"High","gaps":["Whether miR-125a-5p is essential or redundant in mammalian somitogenesis was untested","Other post-transcriptional regulators of Lfng oscillation were not characterized"]},{"year":2014,"claim":"An allelic series of Lfng hypomorphic mice showed that the amplitude of oscillatory LFNG expression quantitatively modulates segmentation clock period, establishing LFNG dosage as a tunable parameter of the clock rather than a simple on/off switch.","evidence":"Quantitative clock period measurements in Lfng hypomorphic allelic series in mouse","pmids":["24560643"],"confidence":"Medium","gaps":["The mechanism by which LFNG dosage translates to clock period change was not molecularly resolved","Differential effects on anterior versus posterior body axis were descriptive"]},{"year":2016,"claim":"A knock-in replacing LFNG's signal sequence with a Golgi-retention motif showed that LFNG secretion and normal N-terminal processing are required for clock function, and that intracellular accumulation of LFNG creates dominant gain-of-function phenotypes including Hes7 stabilization.","evidence":"Lfng^RLFNG knock-in mouse with in vivo clock gene expression analysis","pmids":["26811377"],"confidence":"High","gaps":["Whether secreted LFNG has extracellular signaling functions or secretion simply controls intracellular levels was unclear","The molecular basis by which retained LFNG stabilizes Hes7 was not defined"]},{"year":2017,"claim":"Mutation of miR-125 binding sites in the mouse Lfng 3′ UTR confirmed their role in transcript turnover in the presomitic mesoderm, but germline loss of miR-125a-5p did not disrupt somitogenesis, indicating compensatory mechanisms exist in mammals.","evidence":"3′ UTR reporter transgenes and germline miR-125a-5p knockout in mouse","pmids":["28710840"],"confidence":"Medium","gaps":["Identity of compensatory miRNAs or RNA-binding proteins was not determined","Partial discordance with chick data leaves the essential post-transcriptional regulators in mammals unresolved"]},{"year":2018,"claim":"Identification of the p.D201N variant in the DxD catalytic motif as enzymatically dead, causing spondylocostal dysostosis type 3, directly linked LFNG glycosyltransferase activity to human congenital vertebral segmentation defects.","evidence":"In vitro glycosyltransferase enzyme assay on active-site mutant; compound heterozygous patient sequencing","pmids":["30531807"],"confidence":"Medium","gaps":["Only a single patient family was reported","No structural basis for why D201N abolishes activity was provided"]},{"year":2018,"claim":"Demonstration that TGFBR2 signaling upregulates LFNG to increase GlcNAc incorporation into Notch1 in colorectal cancer cells revealed an upstream regulatory input linking TGF-β pathway to Notch glycosylation status.","evidence":"TGFBR2-reconstituted HCT116 cells with radiolabeled GlcNAc incorporation and Notch1 immunoprecipitation","pmids":["27156840"],"confidence":"Medium","gaps":["Whether this TGF-β–LFNG–Notch axis operates in non-cancer contexts was not tested","Functional consequences for Notch signaling output were not directly measured"]},{"year":2022,"claim":"Mass spectrometry and genetic epistasis showed that LFNG glycosylates DLL1 and DLL3 ligands in signal-sending cells, and that DLL3 loss is epistatic to LFNG loss in the segmentation clock, establishing that LFNG functions on both receptor and ligand sides of Notch signaling.","evidence":"Mass spectrometry of glycosylated EGF repeats, Dll3/Lfng double-mutant mouse, cell-based Notch signaling assays","pmids":["35429490"],"confidence":"High","gaps":["Which specific EGF repeats on DLL1/DLL3 are functionally critical targets of LFNG glycosylation was not resolved","Whether LFNG modification of ligands matters outside the segmentation clock context was untested"]},{"year":2024,"claim":"ChIP-seq demonstrated direct androgen receptor binding at the Lfng promoter in Sertoli cells, connecting androgen signaling to LFNG-dependent Notch modification and downstream GDNF production for spermatogonial stem cell maintenance — the first link between hormone-regulated LFNG transcription and germ cell niche function.","evidence":"ChIP-seq, RNA-seq, enzalutamide androgen blockade in Sertoli cells","pmids":["39407201"],"confidence":"Medium","gaps":["Whether LFNG's glycosyltransferase activity is directly required for GDNF regulation was not formally tested","In vivo validation with Sertoli-specific Lfng deletion was not performed"]},{"year":2024,"claim":"Lineage-tracing and conditional deletion revealed that Lfng marks pancreatic centroacinar cells and is required for Notch3-dependent tumor initiation upon Kras/p53 activation, extending LFNG's role from development to cancer initiation.","evidence":"Lineage-specific Cre-mediated Lfng deletion in mouse PDAC models with Kras/p53 mutations","pmids":["39548190"],"confidence":"Medium","gaps":["Whether LFNG's enzymatic activity on Notch3 is the mechanistic basis for tumor initiation was not directly shown","Whether this role is unique to centroacinar cells or generalizable to other pancreatic cell types was not addressed"]},{"year":null,"claim":"A structural understanding of how LFNG recognizes and glycosylates specific EGF repeats on Notch receptors versus ligands, and the mechanism by which LFNG's intracellular trafficking and secretion regulate its clock function, remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No crystal or cryo-EM structure of LFNG in complex with a substrate EGF repeat exists","The functional role of secreted LFNG (extracellular versus disposal) is unknown","The identity of compensatory post-transcriptional regulators in the mammalian segmentation clock is undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,5,6,7,8]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,5,6,9,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,1,2,4]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,5,7,8]}],"complexes":[],"partners":["NOTCH1","NOTCH3","DLL1","DLL3","AR","TGFBR2"],"other_free_text":[]},"mechanistic_narrative":"LFNG (Lunatic Fringe) is a Golgi-resident fucose-specific β1,3-N-acetylglucosaminyltransferase that modifies O-fucose residues on EGF-like repeats of Notch receptors and Notch ligands (DLL1, DLL3), thereby modulating Notch signaling output in both signal-receiving and signal-sending cells [PMID:19061953, PMID:35429490]. In the presomitic mesoderm, LFNG expression oscillates as part of the segmentation clock, where its dosage tunes the clock period, its N-terminal processing and secretion are required for normal clock function, and post-transcriptional regulation via miR-125a-5p-mediated transcript turnover contributes to oscillatory dynamics [PMID:24560643, PMID:26811377, PMID:23484856]. Beyond somitogenesis, LFNG acts downstream of androgen receptor signaling in Sertoli cells to modulate Notch-dependent GDNF production for spermatogonial stem cell maintenance, and marks a pancreatic centroacinar cell population where it is required for Notch3-dependent tumor initiation upon oncogenic Kras activation [PMID:39407201, PMID:39548190]. Loss-of-function mutations in the LFNG catalytic domain, including variants p.D201N and p.R360C, abolish glycosyltransferase activity and cause spondylocostal dysostosis type 3 in humans [PMID:30531807, PMID:38565611]."},"prefetch_data":{"uniprot":{"accession":"Q8NES3","full_name":"Beta-1,3-N-acetylglucosaminyltransferase lunatic fringe","aliases":["O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase"],"length_aa":379,"mass_kda":41.8,"function":"Glycosyltransferase that initiates the elongation of O-linked fucose residues attached to EGF-like repeats in the extracellular domain of Notch molecules. Modulates NOTCH1 activity by modifying O-fucose residues at specific EGF-like domains resulting in inhibition of NOTCH1 activation by JAG1 and enhancement of NOTCH1 activation by DLL1 via an increase in its binding to DLL1 (By similarity). Decreases the binding of JAG1 to NOTCH2 but not that of DLL1 (PubMed:11346656). Essential mediator of somite segmentation and patterning (By similarity)","subcellular_location":"Golgi apparatus; Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/Q8NES3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LFNG","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LFNG","total_profiled":1310},"omim":[{"mim_id":"619623","title":"LEUCINE-RICH REPEAT NEURONAL PROTEIN 1; LRRN1","url":"https://www.omim.org/entry/619623"},{"mim_id":"609813","title":"SPONDYLOCOSTAL DYSOSTOSIS 3, AUTOSOMAL RECESSIVE; SCDO3","url":"https://www.omim.org/entry/609813"},{"mim_id":"608059","title":"HES FAMILY bHLH TRANSCRIPTION FACTOR 7; HES7","url":"https://www.omim.org/entry/608059"},{"mim_id":"605195","title":"MESODERM POSTERIOR BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTOR 2; MESP2","url":"https://www.omim.org/entry/605195"},{"mim_id":"605189","title":"DICKKOPF WNT SIGNALING PATHWAY INHIBITOR 1; DKK1","url":"https://www.omim.org/entry/605189"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear membrane","reliability":"Approved"},{"location":"Golgi apparatus","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"pancreas","ntpm":71.9},{"tissue":"skin 1","ntpm":54.9}],"url":"https://www.proteinatlas.org/search/LFNG"},"hgnc":{"alias_symbol":["SCDO3"],"prev_symbol":[]},"alphafold":{"accession":"Q8NES3","domains":[{"cath_id":"3.90.550.50","chopping":"75-88_109-202_216-309","consensus_level":"high","plddt":94.5617,"start":75,"end":309}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NES3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NES3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NES3-F1-predicted_aligned_error_v6.png","plddt_mean":82.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LFNG","jax_strain_url":"https://www.jax.org/strain/search?query=LFNG"},"sequence":{"accession":"Q8NES3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8NES3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8NES3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NES3"}},"corpus_meta":[{"pmid":"24556651","id":"PMC_24556651","title":"Targeting Met and Notch in the Lfng-deficient, Met-amplified triple-negative breast cancer.","date":"2014","source":"Cancer biology & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/24556651","citation_count":35,"is_preprint":false},{"pmid":"29193607","id":"PMC_29193607","title":"Comparative genomics reveals that loss of lunatic fringe (LFNG) promotes melanoma metastasis.","date":"2018","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29193607","citation_count":22,"is_preprint":false},{"pmid":"23484856","id":"PMC_23484856","title":"Mir-125a-5p-mediated regulation of Lfng is essential for the avian segmentation clock.","date":"2013","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/23484856","citation_count":21,"is_preprint":false},{"pmid":"20503311","id":"PMC_20503311","title":"Autosomal dominant spondylocostal dysostosis in three generations of a Macedonian family: Negative mutation analysis of DLL3, MESP2, HES7, and LFNG.","date":"2010","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/20503311","citation_count":19,"is_preprint":false},{"pmid":"19061953","id":"PMC_19061953","title":"Mutation of the fucose-specific beta1,3 N-acetylglucosaminyltransferase LFNG results in abnormal formation of the spine.","date":"2008","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/19061953","citation_count":18,"is_preprint":false},{"pmid":"26811377","id":"PMC_26811377","title":"Disruption of somitogenesis by a novel dominant allele of Lfng suggests important roles for protein processing and secretion.","date":"2016","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/26811377","citation_count":17,"is_preprint":false},{"pmid":"30531807","id":"PMC_30531807","title":"Identification of novel LFNG mutations in spondylocostal dysostosis.","date":"2018","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30531807","citation_count":16,"is_preprint":false},{"pmid":"27156840","id":"PMC_27156840","title":"Reconstitution of TGFBR2 in HCT116 colorectal cancer cells causes increased LFNG expression and enhanced N-acetyl-d-glucosamine incorporation into Notch1.","date":"2016","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/27156840","citation_count":15,"is_preprint":false},{"pmid":"24560643","id":"PMC_24560643","title":"Posterior skeletal development and the segmentation clock period are sensitive to Lfng dosage during somitogenesis.","date":"2014","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/24560643","citation_count":15,"is_preprint":false},{"pmid":"35429490","id":"PMC_35429490","title":"Lfng and Dll3 cooperate to modulate protein interactions in cis and coordinate oscillatory Notch pathway activation in the segmentation clock.","date":"2022","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35429490","citation_count":11,"is_preprint":false},{"pmid":"22822384","id":"PMC_22822384","title":"A 380-kb Duplication in 7p22.3 Encompassing the LFNG Gene in a Boy with Asperger Syndrome.","date":"2012","source":"Molecular syndromology","url":"https://pubmed.ncbi.nlm.nih.gov/22822384","citation_count":6,"is_preprint":false},{"pmid":"36453506","id":"PMC_36453506","title":"Construction of lncRNA-ceRNA Networks to Reveal the Potential Role of Lfng/Notch1 Signaling Pathway in Alzheimer's Disease.","date":"2022","source":"Current Alzheimer research","url":"https://pubmed.ncbi.nlm.nih.gov/36453506","citation_count":4,"is_preprint":false},{"pmid":"28710810","id":"PMC_28710810","title":"Putative binding sites for mir-125 family miRNAs in the mouse Lfng 3'UTR affect transcript expression in the segmentation clock, but mir-125a-5p is dispensable for normal somitogenesis.","date":"2017","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/28710810","citation_count":4,"is_preprint":false},{"pmid":"38565611","id":"PMC_38565611","title":"Identification of a novel LFNG variant in a Chinese fetus with spondylocostal dysostosis and a systematic review.","date":"2024","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38565611","citation_count":3,"is_preprint":false},{"pmid":"37038048","id":"PMC_37038048","title":"Identification of bi-allelic LFNG variants in three patients and further clinical and molecular refinement of spondylocostal dysostosis 3.","date":"2023","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37038048","citation_count":3,"is_preprint":false},{"pmid":"19899223","id":"PMC_19899223","title":"Reprint of mutation of the fucose-specific beta1,3 N-acetylglucosaminyltransferase LFNG results in abnormal formation of the spine.","date":"2009","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/19899223","citation_count":3,"is_preprint":false},{"pmid":"39407201","id":"PMC_39407201","title":"Androgen blockage impairs proliferation and function of Sertoli cells via Wee1 and Lfng.","date":"2024","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/39407201","citation_count":2,"is_preprint":false},{"pmid":"37529417","id":"PMC_37529417","title":"tsRNA-15797-modified BMSC-derived exosomes mediate LFNG to induce angiogenesis in osteonecrosis of the femoral head.","date":"2023","source":"Turkish journal of biology = Turk biyoloji dergisi","url":"https://pubmed.ncbi.nlm.nih.gov/37529417","citation_count":2,"is_preprint":false},{"pmid":"39548190","id":"PMC_39548190","title":"Lfng-expressing centroacinar cell is a unique cell-of-origin for p53 deficient pancreatic cancer.","date":"2024","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/39548190","citation_count":0,"is_preprint":false},{"pmid":"40499700","id":"PMC_40499700","title":"Exploring the role of LFNG in hepatoblastoma using multiomics and raise a query in proof link.","date":"2025","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/40499700","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10653,"output_tokens":2812,"usd":0.037069},"stage2":{"model":"claude-opus-4-6","input_tokens":6157,"output_tokens":2938,"usd":0.156353},"total_usd":0.193422,"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\": 2008,\n      \"finding\": \"LFNG encodes a fucose-specific beta1,3-N-acetylglucosaminyltransferase that modifies Notch receptors, thereby altering Notch signaling activity; this glycosylation activity is required for normal somite formation and vertebral column development.\",\n      \"method\": \"Genetic mouse and human mutation studies combined with biochemical characterization of enzymatic function\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — enzymatic function established, replicated across multiple organisms and independently confirmed\",\n      \"pmids\": [\"19061953\", \"19899223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"LFNG protein processing and secretion are required for normal segmentation clock function; replacing the N-terminal signal sequence of LFNG with a Golgi-retention sequence (from Radical fringe) prevents secretion, increases intracellular half-life, and causes dominant somite and skeletal abnormalities distinct from Lfng loss-of-function, perturbing both transcriptional and post-transcriptional regulation of clock components including Hes7.\",\n      \"method\": \"Knock-in mouse allele (Lfng^RLFNG), in vivo gene expression analysis, cyclic gene expression assays in presomitic mesoderm\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean in vivo genetic model with defined molecular phenotype (Hes7 stabilization, altered clock gene expression)\",\n      \"pmids\": [\"26811377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"miR-125a-5p targets evolutionarily conserved sequences in the Lfng 3' UTR to promote transcript instability, and blocking this interaction in vivo perturbs segmentation clock activity and causes abnormal somitogenesis in chick embryos.\",\n      \"method\": \"In vivo miRNA-target blocking experiments in chick embryos, 3'UTR reporter assays, in situ hybridization of clock gene expression\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo functional validation with defined phenotypic readout and molecular mechanism\",\n      \"pmids\": [\"23484856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Mutation of mir-125 binding sites in the mouse Lfng 3'UTR leads to persistent, non-oscillatory reporter transcript expression in the caudal presomitic mesoderm, confirming that these sites regulate transcript turnover in the segmentation clock, though mir-125a-5p itself is dispensable for mouse somitogenesis.\",\n      \"method\": \"3'UTR reporter transgenes in mouse embryos, germline mir-125a-5p knockout, in situ hybridization\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic experiment but reveals compensatory mechanisms and partial discordance with chick data\",\n      \"pmids\": [\"28710840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The level of oscillatory Lfng expression in the presomitic mesoderm modulates the period of the segmentation clock; reduced Lfng oscillation amplitude increases the clock period, and Lfng dosage differentially affects anterior (primary body) versus posterior (secondary body) skeletal development.\",\n      \"method\": \"Allelic series of Lfng hypomorphic mouse lines, quantitative analysis of clock period and skeletal phenotypes\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean in vivo genetic allelic series with quantitative clock period measurements\",\n      \"pmids\": [\"24560643\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LFNG glycosylates EGF-repeats of DLL1 and DLL3 ligands (in addition to Notch receptors), and in signal-sending cells co-expressing DLL1 and NOTCH1, DLL3 can potentiate signal-sending activity in a manner modulated by LFNG; genetic epistasis shows DLL3 loss is epistatic to LFNG loss in the segmentation clock, indicating LFNG can act in signal-sending cells to coordinate oscillatory Notch activation.\",\n      \"method\": \"Double mutant mouse genetic epistasis, mass spectrometry of glycosylated EGF repeats, cell-based Notch signaling assays with DLL1/DLL3/LFNG co-expression\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including mass spectrometry, genetic epistasis, and cell-based functional assays\",\n      \"pmids\": [\"35429490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TGFBR2 signaling upregulates LFNG expression in colorectal cancer cells, which in turn increases N-acetyl-d-glucosamine incorporation into the Notch1 receptor without altering Notch1 protein levels, demonstrating that TGFBR2 can modulate Notch1 glycosylation via LFNG.\",\n      \"method\": \"TGFBR2-reconstituted HCT116 cells, Glyco-Gene Chip, dual radiolabeling ([3H]-GlcNAc and [35S]-methionine), immunoprecipitation of Notch1\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct biochemical demonstration of GlcNAc incorporation into Notch1 via LFNG in a reconstituted cell system\",\n      \"pmids\": [\"27156840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LFNG variant p.D201N in the DxD active-site motif of the glycosyltransferase abolishes enzyme function, as confirmed by in vitro enzyme assay, and causes spondylocostal dysostosis type 3 in a compound heterozygous patient.\",\n      \"method\": \"In vitro glycosyltransferase enzyme assay, compound heterozygous patient sequencing\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic assay with active-site mutant, single study\",\n      \"pmids\": [\"30531807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A novel LFNG missense variant p.R360C causes loss of glycosyltransferase enzyme activity, confirmed by in vitro enzyme assay, and results in spondylocostal dysostosis.\",\n      \"method\": \"In vitro LFNG enzyme activity assay, whole exome sequencing\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro enzymatic activity assay, single study\",\n      \"pmids\": [\"38565611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Androgen receptor (AR) directly binds the Lfng promoter to activate its expression in Sertoli cells; androgen blockade reduces AR binding at the Lfng promoter, decreasing LFNG expression, which impairs Notch modification and reduces GDNF production required for spermatogonial stem cell self-renewal.\",\n      \"method\": \"ChIP-seq (AR binding at Lfng promoter), RNA-seq, enzalutamide androgen blockade model in Sertoli cells\",\n      \"journal\": \"Cell communication and signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP-seq identifies direct AR binding at Lfng promoter with functional downstream readout\",\n      \"pmids\": [\"39407201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Lfng expression marks a centroacinar subpopulation in the pancreas; Lfng deletion blocks tumor initiation from these cells upon oncogenic Kras and p53 deletion, and Notch3 is identified as the functional Notch receptor in this context.\",\n      \"method\": \"Lineage-specific Cre-mediated Lfng deletion in mouse PDAC models, genetic epistasis with Kras and p53 mutations\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic loss-of-function with defined cellular and molecular phenotype\",\n      \"pmids\": [\"39548190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In Lfng-deficient triple-negative breast cancer cells with Met amplification, inhibition of Met downregulates Dll ligands and upregulates Jagged ligands, leading to differential modulation of Notch signaling; Notch inhibition (GSI) alone had no effect but synergized with Met inhibition on cell growth.\",\n      \"method\": \"Pharmacological inhibition (Met inhibitor, GSI), cell-based assays (growth, tumorsphere, colony formation, migration), ligand expression analysis\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — cell-based pharmacological study without direct mechanistic dissection of LFNG function\",\n      \"pmids\": [\"24556651\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LFNG (Lunatic Fringe) encodes a Golgi-resident fucose-specific beta1,3-N-acetylglucosaminyltransferase that modifies O-fucose residues on EGF-like repeats of Notch receptors (and Notch ligands DLL1/DLL3), thereby modulating Notch signaling activity; in the presomitic mesoderm, LFNG expression oscillates as part of the segmentation clock and its cyclic activity periodically represses Notch signaling to pace somitogenesis, with clock period sensitive to LFNG dosage and transcript turnover regulated post-transcriptionally by miR-125a-5p targeting the Lfng 3'UTR; LFNG also requires N-terminal processing and secretion for proper clock function, and loss-of-function mutations in its DxD catalytic motif abolish glycosyltransferase activity and cause spondylocostal dysostosis type 3 in humans.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LFNG (Lunatic Fringe) is a Golgi-resident fucose-specific β1,3-N-acetylglucosaminyltransferase that modifies O-fucose residues on EGF-like repeats of Notch receptors and Notch ligands (DLL1, DLL3), thereby modulating Notch signaling output in both signal-receiving and signal-sending cells [PMID:19061953, PMID:35429490]. In the presomitic mesoderm, LFNG expression oscillates as part of the segmentation clock, where its dosage tunes the clock period, its N-terminal processing and secretion are required for normal clock function, and post-transcriptional regulation via miR-125a-5p-mediated transcript turnover contributes to oscillatory dynamics [PMID:24560643, PMID:26811377, PMID:23484856]. Beyond somitogenesis, LFNG acts downstream of androgen receptor signaling in Sertoli cells to modulate Notch-dependent GDNF production for spermatogonial stem cell maintenance, and marks a pancreatic centroacinar cell population where it is required for Notch3-dependent tumor initiation upon oncogenic Kras activation [PMID:39407201, PMID:39548190]. Loss-of-function mutations in the LFNG catalytic domain, including variants p.D201N and p.R360C, abolish glycosyltransferase activity and cause spondylocostal dysostosis type 3 in humans [PMID:30531807, PMID:38565611].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing that LFNG encodes a fucose-specific β1,3-N-acetylglucosaminyltransferase that glycosylates Notch receptors resolved the molecular basis by which Fringe proteins modulate Notch signaling and explained the somitogenesis defects observed in Lfng mutant mice and humans.\",\n      \"evidence\": \"Genetic studies in mouse and human combined with biochemical characterization of enzymatic specificity\",\n      \"pmids\": [\"19061953\", \"19899223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether LFNG modifies Notch ligands in addition to receptors was unknown\",\n        \"How LFNG protein processing and turnover contribute to clock function was unresolved\",\n        \"No structural model of LFNG-substrate interaction existed\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating that miR-125a-5p targets the Lfng 3′ UTR to destabilize its transcript in vivo revealed a post-transcriptional mechanism contributing to the oscillatory expression pattern required by the segmentation clock.\",\n      \"evidence\": \"In vivo miRNA-target blocking in chick embryos with 3′ UTR reporter assays and clock gene expression analysis\",\n      \"pmids\": [\"23484856\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether miR-125a-5p is essential or redundant in mammalian somitogenesis was untested\",\n        \"Other post-transcriptional regulators of Lfng oscillation were not characterized\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"An allelic series of Lfng hypomorphic mice showed that the amplitude of oscillatory LFNG expression quantitatively modulates segmentation clock period, establishing LFNG dosage as a tunable parameter of the clock rather than a simple on/off switch.\",\n      \"evidence\": \"Quantitative clock period measurements in Lfng hypomorphic allelic series in mouse\",\n      \"pmids\": [\"24560643\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The mechanism by which LFNG dosage translates to clock period change was not molecularly resolved\",\n        \"Differential effects on anterior versus posterior body axis were descriptive\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"A knock-in replacing LFNG's signal sequence with a Golgi-retention motif showed that LFNG secretion and normal N-terminal processing are required for clock function, and that intracellular accumulation of LFNG creates dominant gain-of-function phenotypes including Hes7 stabilization.\",\n      \"evidence\": \"Lfng^RLFNG knock-in mouse with in vivo clock gene expression analysis\",\n      \"pmids\": [\"26811377\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether secreted LFNG has extracellular signaling functions or secretion simply controls intracellular levels was unclear\",\n        \"The molecular basis by which retained LFNG stabilizes Hes7 was not defined\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Mutation of miR-125 binding sites in the mouse Lfng 3′ UTR confirmed their role in transcript turnover in the presomitic mesoderm, but germline loss of miR-125a-5p did not disrupt somitogenesis, indicating compensatory mechanisms exist in mammals.\",\n      \"evidence\": \"3′ UTR reporter transgenes and germline miR-125a-5p knockout in mouse\",\n      \"pmids\": [\"28710840\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Identity of compensatory miRNAs or RNA-binding proteins was not determined\",\n        \"Partial discordance with chick data leaves the essential post-transcriptional regulators in mammals unresolved\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identification of the p.D201N variant in the DxD catalytic motif as enzymatically dead, causing spondylocostal dysostosis type 3, directly linked LFNG glycosyltransferase activity to human congenital vertebral segmentation defects.\",\n      \"evidence\": \"In vitro glycosyltransferase enzyme assay on active-site mutant; compound heterozygous patient sequencing\",\n      \"pmids\": [\"30531807\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Only a single patient family was reported\",\n        \"No structural basis for why D201N abolishes activity was provided\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstration that TGFBR2 signaling upregulates LFNG to increase GlcNAc incorporation into Notch1 in colorectal cancer cells revealed an upstream regulatory input linking TGF-β pathway to Notch glycosylation status.\",\n      \"evidence\": \"TGFBR2-reconstituted HCT116 cells with radiolabeled GlcNAc incorporation and Notch1 immunoprecipitation\",\n      \"pmids\": [\"27156840\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether this TGF-β–LFNG–Notch axis operates in non-cancer contexts was not tested\",\n        \"Functional consequences for Notch signaling output were not directly measured\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Mass spectrometry and genetic epistasis showed that LFNG glycosylates DLL1 and DLL3 ligands in signal-sending cells, and that DLL3 loss is epistatic to LFNG loss in the segmentation clock, establishing that LFNG functions on both receptor and ligand sides of Notch signaling.\",\n      \"evidence\": \"Mass spectrometry of glycosylated EGF repeats, Dll3/Lfng double-mutant mouse, cell-based Notch signaling assays\",\n      \"pmids\": [\"35429490\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Which specific EGF repeats on DLL1/DLL3 are functionally critical targets of LFNG glycosylation was not resolved\",\n        \"Whether LFNG modification of ligands matters outside the segmentation clock context was untested\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"ChIP-seq demonstrated direct androgen receptor binding at the Lfng promoter in Sertoli cells, connecting androgen signaling to LFNG-dependent Notch modification and downstream GDNF production for spermatogonial stem cell maintenance — the first link between hormone-regulated LFNG transcription and germ cell niche function.\",\n      \"evidence\": \"ChIP-seq, RNA-seq, enzalutamide androgen blockade in Sertoli cells\",\n      \"pmids\": [\"39407201\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether LFNG's glycosyltransferase activity is directly required for GDNF regulation was not formally tested\",\n        \"In vivo validation with Sertoli-specific Lfng deletion was not performed\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Lineage-tracing and conditional deletion revealed that Lfng marks pancreatic centroacinar cells and is required for Notch3-dependent tumor initiation upon Kras/p53 activation, extending LFNG's role from development to cancer initiation.\",\n      \"evidence\": \"Lineage-specific Cre-mediated Lfng deletion in mouse PDAC models with Kras/p53 mutations\",\n      \"pmids\": [\"39548190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether LFNG's enzymatic activity on Notch3 is the mechanistic basis for tumor initiation was not directly shown\",\n        \"Whether this role is unique to centroacinar cells or generalizable to other pancreatic cell types was not addressed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A structural understanding of how LFNG recognizes and glycosylates specific EGF repeats on Notch receptors versus ligands, and the mechanism by which LFNG's intracellular trafficking and secretion regulate its clock function, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No crystal or cryo-EM structure of LFNG in complex with a substrate EGF repeat exists\",\n        \"The functional role of secreted LFNG (extracellular versus disposal) is unknown\",\n        \"The identity of compensatory post-transcriptional regulators in the mammalian segmentation clock is undefined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 5, 6, 7, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 6, 9, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 5, 7, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"NOTCH1\",\n      \"NOTCH3\",\n      \"DLL1\",\n      \"DLL3\",\n      \"AR\",\n      \"TGFBR2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}