{"gene":"B4GALT5","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2018,"finding":"B4GALT5 (together with B4GALT6) encodes lactosylceramide (LacCer) synthase activity in the CNS. Double knockout of B4galt5 and B4galt6 in mice completely abolished LacCer synthase activity and eliminated major brain gangliosides, demonstrating that both genes are required for LacCer synthesis and downstream ganglioside biosynthesis.","method":"Conditional B4galt5 knockout (Nestin-Cre) crossed with B4galt6 KO to generate CNS-specific double KO mice; LacCer synthase activity assay; ganglioside biochemical profiling; histological analysis of myelin and neuronal markers","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via double KO with enzymatic activity assay and multiple orthogonal phenotypic readouts; demonstrates that both B4GALT5 and B4GALT6 are necessary for LacCer synthase activity in the CNS","pmids":["30114188"],"is_preprint":false},{"year":2018,"finding":"Loss of B4GALT5/6-dependent gangliosides (e.g., GM1a) impairs neurosphere interaction with laminin, leading to defects in neurite outgrowth and branch formation, and impairs perineuronal net (PNN) formation and axonal/myelin formation in vivo.","method":"Neurosphere culture from double KO mice; neurite outgrowth assay; laminin adhesion assay; immunohistochemistry for myelin-associated proteins and PNN markers","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function with defined cellular phenotypes and pathway placement (ganglioside-laminin interaction), replicated in vitro and in vivo","pmids":["30114188"],"is_preprint":false},{"year":2023,"finding":"B4GalT5 physically interacts with UGCG (UDP-glucose ceramide glycosyltransferase), and limiting B4GalT5 expression impaired UGCG's ability to promote cardiomyocyte hypertrophy, placing B4GalT5 downstream of UGCG in the sphingolipid-ERK-mitochondrial oxidative stress pathway driving cardiac hypertrophy.","method":"Co-immunoprecipitation; B4GalT5 knockdown in cardiomyocytes with UGCG overexpression; ERK pathway and oxidative stress markers measured in vitro and in vivo (pressure overload mouse model)","journal":"Cellular & molecular biology letters","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP interaction plus functional epistasis (KD rescue experiment), single lab, multiple readouts","pmids":["37658291"],"is_preprint":false},{"year":2023,"finding":"B4GALT5 promotes cardiac fibrosis by directly interacting with laminin and activating the Akt/GSK-3β/β-catenin signaling pathway, promoting cardiac fibroblast-to-myofibroblast transformation and collagen deposition.","method":"AAV9-shB4GALT5 knockdown in transverse aortic constriction (TAC) mouse model; B4GALT5 overexpression in vitro; co-immunoprecipitation with laminin; Akt/GSK-3β/β-catenin pathway analysis; histological staining for collagen","journal":"European journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP plus gain/loss-of-function in vivo and in vitro, single lab, two orthogonal approaches","pmids":["38081351"],"is_preprint":false},{"year":2025,"finding":"B4GALT5 suppresses MHC-I expression in pancreatic cancer cells through the endoplasmic reticulum-associated degradation (ERAD) pathway, enabling tumor cells to evade CD8+ T-cell immune surveillance.","method":"RNA sequencing; co-immunoprecipitation; animal models (tumor-infiltrating CD8+ T cell quantification and activity); B4GALT5 knockdown/overexpression in PDAC cells","journal":"Journal for immunotherapy of cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus in vivo and in vitro functional studies with defined mechanistic pathway (ERAD), single lab","pmids":["40316305"],"is_preprint":false},{"year":2025,"finding":"B4GALT5 is a direct substrate-level target of miR-491-5p: miR-491-5p binds the 3'-UTR of B4GalT5 mRNA, suppresses its expression, and thereby attenuates airway smooth muscle cell proliferation, cytokine release, mitochondrial dysfunction, and oxidative stress associated with asthma.","method":"Dual-luciferase reporter assay (3'-UTR binding validation); miR-491-5p mimic transfection in airway smooth muscle cells; OVA-induced asthma mouse model with AAV-miR-491-5p; oxidative stress markers (ROS, MDA, SOD, ATP); histological staining","journal":"Journal of inflammation research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter validation plus in vivo and in vitro functional studies, single lab","pmids":["40896538"],"is_preprint":false},{"year":2026,"finding":"B4GALT5 directly interacts with YWHAZ (14-3-3ζ) and catalyzes N-glycosylation of YWHAZ at the N95 site, enhancing YWHAZ binding to FOXO3a, which promotes FOXO3a ubiquitination and degradation, preventing its nuclear translocation during H. pylori-induced gastric carcinogenesis.","method":"Lectin microarray; co-immunoprecipitation; site-directed mutagenesis of YWHAZ N95 site; in situ tumor-bearing mouse model; B4GALT5 overexpression/knockdown in gastric epithelial cells","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, site-directed mutagenesis, and in vivo rescue experiment, single lab, multiple orthogonal methods","pmids":["42097241"],"is_preprint":false},{"year":2025,"finding":"B4GALT5 synthesizes lactosylceramide (LacCer), the obligate precursor for Gb3 glycosphingolipid. CRISPR/Cas9 knockout of B4GALT5 in CHO-Lec2 cells abolished Gb3 but not glycoprotein-based P1 glycotope, and rendered cells resistant to Shiga toxin 1 and 2 binding/cytotoxicity.","method":"CRISPR/Cas9 gene disruption; Shiga toxin binding assay; cytotoxicity assay; glycolipid biochemical analysis","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — CRISPR/Cas9 loss-of-function with direct biochemical validation of enzyme product (LacCer/Gb3 loss) and functional cytotoxicity readout, corroborated by preprint version","pmids":["40036900"],"is_preprint":false},{"year":2025,"finding":"eIF2B enhances translation of B4GALT5 mRNA, upregulating glycosphingolipid (GSL) biosynthesis (GM3 and SM4), which remodels plasma membrane lipid composition to facilitate eIF2B:SOS:mutant KRAS complex formation and mutant KRAS nanoclustering and activation.","method":"Translational regulation assay; GSL metabolite profiling; plasma membrane lipid composition analysis; mutant KRAS nanoclustering and activity assays in cancer cells","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single lab, mechanistic link to B4GALT5 as translational target is described but abstracts compress methods; B4GALT5 role is one step in a broader eIF2B/KRAS pathway","pmids":[],"is_preprint":true},{"year":2018,"finding":"Porcine B4GALT5 physically interacts with PRRSV glycoprotein GP5, as detected by co-immunoprecipitation, and co-localizes with GP5 in Golgi membranes; B4GALT5 overexpression modestly inhibited PRRSV proliferation and upregulated inflammatory cytokines and antigen-presenting surface glycoproteins.","method":"Co-immunoprecipitation; confocal microscopy co-localization; B4GALT5 overexpression with viral titer measurement; qRT-PCR for cytokines","journal":"Frontiers in cellular and infection microbiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP in porcine cells, single lab, porcine ortholog with limited mechanistic follow-up","pmids":["29546034"],"is_preprint":false}],"current_model":"B4GALT5 encodes a β-1,4-galactosyltransferase (LacCer synthase) that catalyzes the synthesis of lactosylceramide from glucosylceramide, serving as the committed step for ganglioside and globoside (Gb3) biosynthesis; in the CNS, B4GALT5 acts redundantly with B4GALT6 to generate gangliosides required for neuronal maturation, myelin formation, and laminin-dependent neurite outgrowth, while in non-neural contexts B4GALT5 glycosylates protein substrates (e.g., YWHAZ at N95) and interacts with partners such as UGCG, laminin, and MHC-I machinery to modulate cardiac fibrosis, cardiomyocyte hypertrophy, and tumor immune evasion via the ERAD pathway."},"narrative":{"mechanistic_narrative":"B4GALT5 encodes a β-1,4-galactosyltransferase that synthesizes lactosylceramide (LacCer) from glucosylceramide, the committed precursor step for downstream glycosphingolipid biosynthesis [PMID:30114188, PMID:40036900]. In the CNS, B4GALT5 acts redundantly with B4GALT6 to generate brain gangliosides: double knockout abolishes LacCer synthase activity and eliminates major gangliosides, and the resulting loss of ganglioside-laminin interaction impairs neurite outgrowth, perineuronal net formation, and axonal/myelin development [PMID:30114188]. Its LacCer product is also the obligate precursor for the globoside Gb3, such that B4GALT5 disruption abolishes Gb3 and confers resistance to Shiga toxin binding and cytotoxicity [PMID:40036900]. Beyond glycolipid synthesis, B4GALT5 participates in disease-associated signaling and protein glycosylation: it interacts with UGCG to drive a sphingolipid-ERK-oxidative stress axis promoting cardiomyocyte hypertrophy [PMID:37658291], binds laminin to activate Akt/GSK-3β/β-catenin signaling in cardiac fibrosis [PMID:38081351], suppresses MHC-I via the ERAD pathway to enable tumor immune evasion [PMID:40316305], and catalyzes N-glycosylation of YWHAZ (14-3-3ζ) at N95 to promote FOXO3a degradation during gastric carcinogenesis [PMID:42097241].","teleology":[{"year":2018,"claim":"Established that B4GALT5, acting redundantly with B4GALT6, is genetically required for LacCer synthase activity and ganglioside production in the CNS, resolving which enzyme(s) commit the ganglioside pathway in brain.","evidence":"CNS-specific B4galt5/B4galt6 double knockout mice with LacCer synthase activity assay and ganglioside profiling","pmids":["30114188"],"confidence":"High","gaps":["Does not resolve the individual catalytic contribution of B4GALT5 versus B4GALT6 in non-CNS tissues","No structural basis for substrate specificity"]},{"year":2018,"claim":"Connected ganglioside loss to a defined cellular mechanism by showing B4GALT5/6-dependent gangliosides mediate neurosphere-laminin interaction required for neurite outgrowth, PNN, and myelin formation.","evidence":"Neurosphere and neurite outgrowth/laminin adhesion assays from double KO mice plus in vivo immunohistochemistry","pmids":["30114188"],"confidence":"High","gaps":["Which specific ganglioside species mediates laminin binding is not pinpointed","Molecular receptor linking gangliosides to laminin not identified"]},{"year":2018,"claim":"Tested whether B4GALT5 acts on viral glycoproteins, finding the porcine ortholog interacts with and co-localizes with PRRSV GP5 in the Golgi and modestly restricts viral replication.","evidence":"Co-IP and confocal co-localization in porcine cells with overexpression viral titer measurement","pmids":["29546034"],"confidence":"Low","gaps":["Single Co-IP in porcine ortholog without reciprocal validation","Restriction effect modest and mechanistically undefined","Human relevance not established"]},{"year":2023,"claim":"Placed B4GALT5 downstream of UGCG in a sphingolipid-driven cardiac hypertrophy pathway, addressing how glucosylceramide synthesis feeds hypertrophic signaling.","evidence":"Co-IP plus B4GalT5 knockdown rescue of UGCG-driven hypertrophy with ERK/oxidative-stress readouts in vitro and pressure-overload model","pmids":["37658291"],"confidence":"Medium","gaps":["Whether the effect requires B4GALT5 catalytic activity or only physical interaction unclear","Single lab"]},{"year":2023,"claim":"Identified a laminin-binding, pro-fibrotic role for B4GALT5 via Akt/GSK-3β/β-catenin activation in fibroblast-to-myofibroblast transition.","evidence":"AAV9 knockdown in TAC model, in vitro overexpression, laminin Co-IP, and pathway/collagen analysis","pmids":["38081351"],"confidence":"Medium","gaps":["Direct vs indirect nature of laminin interaction not fully resolved","Single lab","Catalytic dependence not tested"]},{"year":2025,"claim":"Defined a non-glycolipid immune-evasion mechanism in which B4GALT5 suppresses MHC-I through ERAD, attenuating CD8+ T-cell surveillance of pancreatic cancer.","evidence":"RNA-seq, Co-IP, knockdown/overexpression in PDAC cells, and in vivo tumor-infiltrating CD8+ T-cell quantification","pmids":["40316305"],"confidence":"Medium","gaps":["ERAD substrate directly engaged by B4GALT5 not identified","Whether MHC-I suppression depends on glycosyltransferase activity unclear","Single lab"]},{"year":2025,"claim":"Confirmed B4GALT5 as the LacCer synthase generating the Gb3 receptor for Shiga toxin, distinguishing its glycolipid role from glycoprotein-based glycotopes.","evidence":"CRISPR/Cas9 knockout in CHO-Lec2 cells with Gb3/P1 glycolipid analysis and Shiga toxin binding/cytotoxicity assays","pmids":["40036900"],"confidence":"High","gaps":["Does not address redundancy with B4GALT6 in this system","Tissue-specific contribution to Gb3 in humans not measured"]},{"year":2025,"claim":"Identified miR-491-5p as a post-transcriptional repressor of B4GALT5 that limits airway smooth muscle proliferation and oxidative stress in asthma.","evidence":"Dual-luciferase 3'-UTR reporter, miR mimic transfection, and OVA-induced asthma mouse model with AAV-miR-491-5p","pmids":["40896538"],"confidence":"Medium","gaps":["Which downstream B4GALT5 product mediates the asthma phenotype not defined","Single lab"]},{"year":2025,"claim":"Proposed B4GALT5 as a translationally upregulated node downstream of eIF2B that remodels membrane glycosphingolipids to promote mutant KRAS nanoclustering.","evidence":"Translational regulation and GSL profiling with KRAS nanoclustering/activity assays (preprint)","pmids":[],"confidence":"Low","gaps":["Preprint, not peer reviewed","B4GALT5 is one step in a broader eIF2B/KRAS pathway and its specific necessity is not isolated"]},{"year":2026,"claim":"Demonstrated B4GALT5 directly glycosylates a protein substrate, N-glycosylating YWHAZ at N95 to enhance FOXO3a binding and degradation during gastric carcinogenesis, extending its activity beyond glycolipids.","evidence":"Lectin microarray, Co-IP, YWHAZ N95 site-directed mutagenesis, and in vivo tumor-bearing mouse model","pmids":["42097241"],"confidence":"Medium","gaps":["Whether protein N-glycosylation is a general B4GALT5 activity or YWHAZ-specific unknown","Single lab","Structural/enzymatic detail of protein glycosylation absent"]},{"year":null,"claim":"It remains unresolved whether B4GALT5's disease-associated signaling roles (cardiac, tumor immune, protein glycosylation) depend on its canonical LacCer synthase catalytic activity or on activity-independent protein interactions.","evidence":"No catalytic-dead rescue experiments across the non-glycolipid phenotypes in the corpus","pmids":[],"confidence":"Low","gaps":["No catalytic-dead mutant tested in cardiac, immune, or protein-glycosylation contexts","No structural model of substrate engagement"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,7,6]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[9]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,7]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["UGCG","YWHAZ","LAMININ","FOXO3A","GP5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43286","full_name":"Beta-1,4-galactosyltransferase 5","aliases":["Beta-1,4-GalT II","Glucosylceramide beta-1,4-galactosyltransferase","Lactosylceramide synthase","LacCer synthase","UDP-Gal:beta-GlcNAc beta-1,4-galactosyltransferase 5","UDP-galactose:beta-N-acetylglucosamine beta-1,4-galactosyltransferase 5"],"length_aa":388,"mass_kda":45.1,"function":"Catalyzes the synthesis of lactosylceramide (LacCer) via the transfer of galactose from UDP-galactose to glucosylceramide (GlcCer) (PubMed:24498430). LacCer is the starting point in the biosynthesis of all gangliosides (membrane-bound glycosphingolipids) which play pivotal roles in the CNS including neuronal maturation and axonal and myelin formation (By similarity). Plays a role in the glycosylation of BMPR1A and regulation of its protein stability (By similarity). Essential for extraembryonic development during early embryogenesis (By similarity)","subcellular_location":"Golgi apparatus, Golgi stack membrane; Golgi apparatus","url":"https://www.uniprot.org/uniprotkb/O43286/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/B4GALT5","classification":"Not Classified","n_dependent_lines":22,"n_total_lines":1208,"dependency_fraction":0.018211920529801324},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/B4GALT5","total_profiled":1310},"omim":[{"mim_id":"613569","title":"SAD1 AND UNC84 DOMAIN-CONTAINING PROTEIN 2; SUN2","url":"https://www.omim.org/entry/613569"},{"mim_id":"604017","title":"UDP-GAL:BETA-GlcNAc BETA-1,4-GALACTOSYLTRANSFERASE, POLYPEPTIDE 6; B4GALT6","url":"https://www.omim.org/entry/604017"},{"mim_id":"604016","title":"UDP-GAL:BETA-GlcNAc BETA-1,4-GALACTOSYLTRANSFERASE, POLYPEPTIDE 5; B4GALT5","url":"https://www.omim.org/entry/604016"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/B4GALT5"},"hgnc":{"alias_symbol":["beta4GalT-V"],"prev_symbol":[]},"alphafold":{"accession":"O43286","domains":[{"cath_id":"3.90.550.10","chopping":"135-384","consensus_level":"high","plddt":95.6394,"start":135,"end":384},{"cath_id":"1.20.5","chopping":"25-68","consensus_level":"medium","plddt":80.4848,"start":25,"end":68}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43286","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43286-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43286-F1-predicted_aligned_error_v6.png","plddt_mean":87.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=B4GALT5","jax_strain_url":"https://www.jax.org/strain/search?query=B4GALT5"},"sequence":{"accession":"O43286","fasta_url":"https://rest.uniprot.org/uniprotkb/O43286.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43286/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43286"}},"corpus_meta":[{"pmid":"30114188","id":"PMC_30114188","title":"Lactosylceramide synthases encoded by B4galt5 and 6 genes are pivotal for neuronal generation and myelin formation in mice.","date":"2018","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30114188","citation_count":51,"is_preprint":false},{"pmid":"34709725","id":"PMC_34709725","title":"Circ_0009910 sponges miR-491-5p to promote acute myeloid leukemia progression through modulating B4GALT5 expression and PI3K/AKT signaling pathway.","date":"2021","source":"International journal of laboratory hematology","url":"https://pubmed.ncbi.nlm.nih.gov/34709725","citation_count":23,"is_preprint":false},{"pmid":"29546034","id":"PMC_29546034","title":"The Immunological Regulation Roles of Porcine β-1, 4 Galactosyltransferase V (B4GALT5) in PRRSV Infection.","date":"2018","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/29546034","citation_count":15,"is_preprint":false},{"pmid":"37658291","id":"PMC_37658291","title":"UGCG modulates heart hypertrophy through B4GalT5-mediated mitochondrial oxidative stress and the ERK signaling pathway.","date":"2023","source":"Cellular & molecular biology letters","url":"https://pubmed.ncbi.nlm.nih.gov/37658291","citation_count":14,"is_preprint":false},{"pmid":"40316305","id":"PMC_40316305","title":"B4GALT5 inhibits CD8+ T-cell response by downregulating MHC-I level through ERAD pathway in PDAC.","date":"2025","source":"Journal for immunotherapy of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/40316305","citation_count":6,"is_preprint":false},{"pmid":"38081351","id":"PMC_38081351","title":"Downregulation of B4GALT5 attenuates cardiac fibrosis through Lumican and Akt/GSK-3β/β-catenin pathway.","date":"2023","source":"European journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/38081351","citation_count":3,"is_preprint":false},{"pmid":"40036900","id":"PMC_40036900","title":"B4GALT5-deficient CHO-Lec2 cells expressing human α1,4-galactosyltransferase: A glycoengineered cell model for studying Shiga toxin receptors.","date":"2025","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/40036900","citation_count":1,"is_preprint":false},{"pmid":"39422791","id":"PMC_39422791","title":"Ginsenoside 20(S)-Rg3 Hinders Esophageal Squamous Cell Carcinoma Cells Malignant Behaviors by miR-210-3p/B4GALT5 Axis.","date":"2024","source":"Cell biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/39422791","citation_count":1,"is_preprint":false},{"pmid":"40896538","id":"PMC_40896538","title":"MiR-491-5p Targets B4GalT5 to Alleviate Airway Inflammation and Remodeling in Asthma by Regulating Pulmonary Oxidative Stress.","date":"2025","source":"Journal of inflammation research","url":"https://pubmed.ncbi.nlm.nih.gov/40896538","citation_count":0,"is_preprint":false},{"pmid":"42097241","id":"PMC_42097241","title":"Mechanism of Helicobacter pylori-induced FOXO3a ubiquitination and degradation in gastric epithelial cells by modifying YWHAZ through B4GALT5-mediated glycosylation during gastric carcinogenesis.","date":"2026","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/42097241","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.10.686860","title":"eIF2B Selectively Anchors and Activates Mutant KRAS","date":"2025-11-12","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.10.686860","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.26.620404","title":"<i>B4GALT5</i>  -deficient CHO-Lec2 cells expressing human α1,4-galactosyltransferase: a glycoengineered cell model for studying Shiga toxin receptors","date":"2024-10-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.26.620404","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.11.17.24317460","title":"Phenome-wide causal proteomics enhance systemic lupus erythematosus flare prediction: A study in Asian populations","date":"2024-11-18","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.17.24317460","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10382,"output_tokens":2866,"usd":0.037068,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10097,"output_tokens":3415,"usd":0.06793,"stage2_stop_reason":"end_turn"},"total_usd":0.104998,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"B4GALT5 (together with B4GALT6) encodes lactosylceramide (LacCer) synthase activity in the CNS. Double knockout of B4galt5 and B4galt6 in mice completely abolished LacCer synthase activity and eliminated major brain gangliosides, demonstrating that both genes are required for LacCer synthesis and downstream ganglioside biosynthesis.\",\n      \"method\": \"Conditional B4galt5 knockout (Nestin-Cre) crossed with B4galt6 KO to generate CNS-specific double KO mice; LacCer synthase activity assay; ganglioside biochemical profiling; histological analysis of myelin and neuronal markers\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via double KO with enzymatic activity assay and multiple orthogonal phenotypic readouts; demonstrates that both B4GALT5 and B4GALT6 are necessary for LacCer synthase activity in the CNS\",\n      \"pmids\": [\"30114188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Loss of B4GALT5/6-dependent gangliosides (e.g., GM1a) impairs neurosphere interaction with laminin, leading to defects in neurite outgrowth and branch formation, and impairs perineuronal net (PNN) formation and axonal/myelin formation in vivo.\",\n      \"method\": \"Neurosphere culture from double KO mice; neurite outgrowth assay; laminin adhesion assay; immunohistochemistry for myelin-associated proteins and PNN markers\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function with defined cellular phenotypes and pathway placement (ganglioside-laminin interaction), replicated in vitro and in vivo\",\n      \"pmids\": [\"30114188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"B4GalT5 physically interacts with UGCG (UDP-glucose ceramide glycosyltransferase), and limiting B4GalT5 expression impaired UGCG's ability to promote cardiomyocyte hypertrophy, placing B4GalT5 downstream of UGCG in the sphingolipid-ERK-mitochondrial oxidative stress pathway driving cardiac hypertrophy.\",\n      \"method\": \"Co-immunoprecipitation; B4GalT5 knockdown in cardiomyocytes with UGCG overexpression; ERK pathway and oxidative stress markers measured in vitro and in vivo (pressure overload mouse model)\",\n      \"journal\": \"Cellular & molecular biology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP interaction plus functional epistasis (KD rescue experiment), single lab, multiple readouts\",\n      \"pmids\": [\"37658291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"B4GALT5 promotes cardiac fibrosis by directly interacting with laminin and activating the Akt/GSK-3β/β-catenin signaling pathway, promoting cardiac fibroblast-to-myofibroblast transformation and collagen deposition.\",\n      \"method\": \"AAV9-shB4GALT5 knockdown in transverse aortic constriction (TAC) mouse model; B4GALT5 overexpression in vitro; co-immunoprecipitation with laminin; Akt/GSK-3β/β-catenin pathway analysis; histological staining for collagen\",\n      \"journal\": \"European journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP plus gain/loss-of-function in vivo and in vitro, single lab, two orthogonal approaches\",\n      \"pmids\": [\"38081351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"B4GALT5 suppresses MHC-I expression in pancreatic cancer cells through the endoplasmic reticulum-associated degradation (ERAD) pathway, enabling tumor cells to evade CD8+ T-cell immune surveillance.\",\n      \"method\": \"RNA sequencing; co-immunoprecipitation; animal models (tumor-infiltrating CD8+ T cell quantification and activity); B4GALT5 knockdown/overexpression in PDAC cells\",\n      \"journal\": \"Journal for immunotherapy of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus in vivo and in vitro functional studies with defined mechanistic pathway (ERAD), single lab\",\n      \"pmids\": [\"40316305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"B4GALT5 is a direct substrate-level target of miR-491-5p: miR-491-5p binds the 3'-UTR of B4GalT5 mRNA, suppresses its expression, and thereby attenuates airway smooth muscle cell proliferation, cytokine release, mitochondrial dysfunction, and oxidative stress associated with asthma.\",\n      \"method\": \"Dual-luciferase reporter assay (3'-UTR binding validation); miR-491-5p mimic transfection in airway smooth muscle cells; OVA-induced asthma mouse model with AAV-miR-491-5p; oxidative stress markers (ROS, MDA, SOD, ATP); histological staining\",\n      \"journal\": \"Journal of inflammation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter validation plus in vivo and in vitro functional studies, single lab\",\n      \"pmids\": [\"40896538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"B4GALT5 directly interacts with YWHAZ (14-3-3ζ) and catalyzes N-glycosylation of YWHAZ at the N95 site, enhancing YWHAZ binding to FOXO3a, which promotes FOXO3a ubiquitination and degradation, preventing its nuclear translocation during H. pylori-induced gastric carcinogenesis.\",\n      \"method\": \"Lectin microarray; co-immunoprecipitation; site-directed mutagenesis of YWHAZ N95 site; in situ tumor-bearing mouse model; B4GALT5 overexpression/knockdown in gastric epithelial cells\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, site-directed mutagenesis, and in vivo rescue experiment, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"42097241\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"B4GALT5 synthesizes lactosylceramide (LacCer), the obligate precursor for Gb3 glycosphingolipid. CRISPR/Cas9 knockout of B4GALT5 in CHO-Lec2 cells abolished Gb3 but not glycoprotein-based P1 glycotope, and rendered cells resistant to Shiga toxin 1 and 2 binding/cytotoxicity.\",\n      \"method\": \"CRISPR/Cas9 gene disruption; Shiga toxin binding assay; cytotoxicity assay; glycolipid biochemical analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — CRISPR/Cas9 loss-of-function with direct biochemical validation of enzyme product (LacCer/Gb3 loss) and functional cytotoxicity readout, corroborated by preprint version\",\n      \"pmids\": [\"40036900\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"eIF2B enhances translation of B4GALT5 mRNA, upregulating glycosphingolipid (GSL) biosynthesis (GM3 and SM4), which remodels plasma membrane lipid composition to facilitate eIF2B:SOS:mutant KRAS complex formation and mutant KRAS nanoclustering and activation.\",\n      \"method\": \"Translational regulation assay; GSL metabolite profiling; plasma membrane lipid composition analysis; mutant KRAS nanoclustering and activity assays in cancer cells\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single lab, mechanistic link to B4GALT5 as translational target is described but abstracts compress methods; B4GALT5 role is one step in a broader eIF2B/KRAS pathway\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Porcine B4GALT5 physically interacts with PRRSV glycoprotein GP5, as detected by co-immunoprecipitation, and co-localizes with GP5 in Golgi membranes; B4GALT5 overexpression modestly inhibited PRRSV proliferation and upregulated inflammatory cytokines and antigen-presenting surface glycoproteins.\",\n      \"method\": \"Co-immunoprecipitation; confocal microscopy co-localization; B4GALT5 overexpression with viral titer measurement; qRT-PCR for cytokines\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP in porcine cells, single lab, porcine ortholog with limited mechanistic follow-up\",\n      \"pmids\": [\"29546034\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"B4GALT5 encodes a β-1,4-galactosyltransferase (LacCer synthase) that catalyzes the synthesis of lactosylceramide from glucosylceramide, serving as the committed step for ganglioside and globoside (Gb3) biosynthesis; in the CNS, B4GALT5 acts redundantly with B4GALT6 to generate gangliosides required for neuronal maturation, myelin formation, and laminin-dependent neurite outgrowth, while in non-neural contexts B4GALT5 glycosylates protein substrates (e.g., YWHAZ at N95) and interacts with partners such as UGCG, laminin, and MHC-I machinery to modulate cardiac fibrosis, cardiomyocyte hypertrophy, and tumor immune evasion via the ERAD pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"B4GALT5 encodes a β-1,4-galactosyltransferase that synthesizes lactosylceramide (LacCer) from glucosylceramide, the committed precursor step for downstream glycosphingolipid biosynthesis [#0, #7]. In the CNS, B4GALT5 acts redundantly with B4GALT6 to generate brain gangliosides: double knockout abolishes LacCer synthase activity and eliminates major gangliosides, and the resulting loss of ganglioside-laminin interaction impairs neurite outgrowth, perineuronal net formation, and axonal/myelin development [#0, #1]. Its LacCer product is also the obligate precursor for the globoside Gb3, such that B4GALT5 disruption abolishes Gb3 and confers resistance to Shiga toxin binding and cytotoxicity [#7]. Beyond glycolipid synthesis, B4GALT5 participates in disease-associated signaling and protein glycosylation: it interacts with UGCG to drive a sphingolipid-ERK-oxidative stress axis promoting cardiomyocyte hypertrophy [#2], binds laminin to activate Akt/GSK-3β/β-catenin signaling in cardiac fibrosis [#3], suppresses MHC-I via the ERAD pathway to enable tumor immune evasion [#4], and catalyzes N-glycosylation of YWHAZ (14-3-3ζ) at N95 to promote FOXO3a degradation during gastric carcinogenesis [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established that B4GALT5, acting redundantly with B4GALT6, is genetically required for LacCer synthase activity and ganglioside production in the CNS, resolving which enzyme(s) commit the ganglioside pathway in brain.\",\n      \"evidence\": \"CNS-specific B4galt5/B4galt6 double knockout mice with LacCer synthase activity assay and ganglioside profiling\",\n      \"pmids\": [\"30114188\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not resolve the individual catalytic contribution of B4GALT5 versus B4GALT6 in non-CNS tissues\", \"No structural basis for substrate specificity\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected ganglioside loss to a defined cellular mechanism by showing B4GALT5/6-dependent gangliosides mediate neurosphere-laminin interaction required for neurite outgrowth, PNN, and myelin formation.\",\n      \"evidence\": \"Neurosphere and neurite outgrowth/laminin adhesion assays from double KO mice plus in vivo immunohistochemistry\",\n      \"pmids\": [\"30114188\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific ganglioside species mediates laminin binding is not pinpointed\", \"Molecular receptor linking gangliosides to laminin not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Tested whether B4GALT5 acts on viral glycoproteins, finding the porcine ortholog interacts with and co-localizes with PRRSV GP5 in the Golgi and modestly restricts viral replication.\",\n      \"evidence\": \"Co-IP and confocal co-localization in porcine cells with overexpression viral titer measurement\",\n      \"pmids\": [\"29546034\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP in porcine ortholog without reciprocal validation\", \"Restriction effect modest and mechanistically undefined\", \"Human relevance not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed B4GALT5 downstream of UGCG in a sphingolipid-driven cardiac hypertrophy pathway, addressing how glucosylceramide synthesis feeds hypertrophic signaling.\",\n      \"evidence\": \"Co-IP plus B4GalT5 knockdown rescue of UGCG-driven hypertrophy with ERK/oxidative-stress readouts in vitro and pressure-overload model\",\n      \"pmids\": [\"37658291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the effect requires B4GALT5 catalytic activity or only physical interaction unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified a laminin-binding, pro-fibrotic role for B4GALT5 via Akt/GSK-3β/β-catenin activation in fibroblast-to-myofibroblast transition.\",\n      \"evidence\": \"AAV9 knockdown in TAC model, in vitro overexpression, laminin Co-IP, and pathway/collagen analysis\",\n      \"pmids\": [\"38081351\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect nature of laminin interaction not fully resolved\", \"Single lab\", \"Catalytic dependence not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a non-glycolipid immune-evasion mechanism in which B4GALT5 suppresses MHC-I through ERAD, attenuating CD8+ T-cell surveillance of pancreatic cancer.\",\n      \"evidence\": \"RNA-seq, Co-IP, knockdown/overexpression in PDAC cells, and in vivo tumor-infiltrating CD8+ T-cell quantification\",\n      \"pmids\": [\"40316305\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"ERAD substrate directly engaged by B4GALT5 not identified\", \"Whether MHC-I suppression depends on glycosyltransferase activity unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Confirmed B4GALT5 as the LacCer synthase generating the Gb3 receptor for Shiga toxin, distinguishing its glycolipid role from glycoprotein-based glycotopes.\",\n      \"evidence\": \"CRISPR/Cas9 knockout in CHO-Lec2 cells with Gb3/P1 glycolipid analysis and Shiga toxin binding/cytotoxicity assays\",\n      \"pmids\": [\"40036900\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address redundancy with B4GALT6 in this system\", \"Tissue-specific contribution to Gb3 in humans not measured\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified miR-491-5p as a post-transcriptional repressor of B4GALT5 that limits airway smooth muscle proliferation and oxidative stress in asthma.\",\n      \"evidence\": \"Dual-luciferase 3'-UTR reporter, miR mimic transfection, and OVA-induced asthma mouse model with AAV-miR-491-5p\",\n      \"pmids\": [\"40896538\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which downstream B4GALT5 product mediates the asthma phenotype not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Proposed B4GALT5 as a translationally upregulated node downstream of eIF2B that remodels membrane glycosphingolipids to promote mutant KRAS nanoclustering.\",\n      \"evidence\": \"Translational regulation and GSL profiling with KRAS nanoclustering/activity assays (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Preprint, not peer reviewed\", \"B4GALT5 is one step in a broader eIF2B/KRAS pathway and its specific necessity is not isolated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrated B4GALT5 directly glycosylates a protein substrate, N-glycosylating YWHAZ at N95 to enhance FOXO3a binding and degradation during gastric carcinogenesis, extending its activity beyond glycolipids.\",\n      \"evidence\": \"Lectin microarray, Co-IP, YWHAZ N95 site-directed mutagenesis, and in vivo tumor-bearing mouse model\",\n      \"pmids\": [\"42097241\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether protein N-glycosylation is a general B4GALT5 activity or YWHAZ-specific unknown\", \"Single lab\", \"Structural/enzymatic detail of protein glycosylation absent\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved whether B4GALT5's disease-associated signaling roles (cardiac, tumor immune, protein glycosylation) depend on its canonical LacCer synthase catalytic activity or on activity-independent protein interactions.\",\n      \"evidence\": \"No catalytic-dead rescue experiments across the non-glycolipid phenotypes in the corpus\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No catalytic-dead mutant tested in cardiac, immune, or protein-glycosylation contexts\", \"No structural model of substrate engagement\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 7, 6]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"UGCG\", \"YWHAZ\", \"laminin\", \"FOXO3a\", \"GP5\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":4,"faith_total":4,"faith_pct":100.0}}