{"gene":"STX6","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2013,"finding":"STX6 forms a complex with CAL (CFTR-associated ligand) and CFTR at the Golgi, and recruits the E3 ubiquitin ligase MARCH2 to this complex; STX6 synergistically enhances MARCH2 binding to CAL, leading to MARCH2-mediated ubiquitination and lysosomal degradation of mature CFTR.","method":"Co-immunoprecipitation, co-localization, in vivo ubiquitination assay, siRNA knockdown, overexpression with catalytically dead RING mutant and PDZ-motif CFTR mutant","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, multiple orthogonal approaches (ubiquitination assay, catalytic mutant, PDZ mutant, siRNA), rigorous controls in single study","pmids":["23818989"],"is_preprint":false},{"year":2016,"finding":"STX6 is recruited to GAS-containing autophagosome-like vacuoles (GcAVs) via its tyrosine-based sorting motif and transmembrane domain, where it forms a SNARE complex with VTI1B and VAMP3 to drive fusion between recycling endosomes and GcAVs, thereby promoting xenophagy of Group A Streptococcus. RABGEF1 mediates this RE-GcAV fusion through the STX6-VAMP3-VTI1B complex.","method":"Knockdown and knockout experiments, co-immunoprecipitation, co-localization with transferrin receptor-positive puncta, domain mutant analysis, live-cell imaging","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO/KD with defined phenotype, Co-IP, domain mutant analysis, and epistasis with RABGEF1 in a single rigorous study","pmids":["27791468"],"is_preprint":false},{"year":2021,"finding":"STX6 forms a trans-SNARE Q-SNARE complex with STX7 and VTI1B that pairs with the R-SNARE VAMP4 on Golgi-derived vesicles to mediate fusion with late endosomes, regulating transport of MT1-MMP to the cell surface in LPS-activated macrophages. Depletion of STX6 reduces surface MT1-MMP and gelatin degradation; overexpression of the Stx6/Stx7/Vti1b complex increases surface MT1-MMP.","method":"Fixed and live imaging, siRNA depletion with functional readout (gelatin degradation assay), overexpression rescue","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD with defined functional readout (degradation assay) and overexpression rescue, single lab, two orthogonal methods","pmids":["34476885"],"is_preprint":false},{"year":2023,"finding":"STX6 is primarily involved in early endosome to trans-Golgi network retrograde transport. Genetic knockout of Stx6 in mice modestly extended prion disease incubation periods (by ~12 days) following RML or ME7 prion inoculation, suggesting a functional role in prion pathogenesis. Stx6-/- mice are viable and fertile with no gross neurological, biochemical, or skeletal impairments under non-disease conditions.","method":"Stx6 knockout mouse model, prion transmission study (inoculation with RML and ME7 prions), histopathological analysis of neuropathology endpoints","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined in vivo phenotypic readout, but modest effect size and single study","pmids":["37996040"],"is_preprint":false},{"year":2016,"finding":"STX6 silencing in esophageal squamous cell carcinoma (ESCC) cells inhibited cell viability and proliferation in a p53-dependent manner, and also impaired integrin trafficking and cell migration.","method":"siRNA silencing, cell viability and proliferation assays, integrin trafficking assay, migration assay","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, KD phenotype without detailed pathway mechanistic validation; integrin trafficking link stated but not deeply characterized","pmids":["26906622"],"is_preprint":false},{"year":2025,"finding":"STX6 is a direct target of miR-375-3p; overexpression of STX6 rescued endothelial cell senescence phenotypes (SA-β-gal staining, p15/IL6/IL8 upregulation) induced by miR-375-3p. Mechanistically, the miR-375-3p/STX6 axis promotes endothelial cell senescence and atherosclerosis via the SMAD2/p15 pathway in a SMAD2-dependent manner.","method":"Luciferase reporter assay (miR-375-3p targeting STX6 3'UTR), STX6 overexpression rescue, in vivo ApoE-/- mouse model with miR-375-3p inhibition, SA-β-gal staining, Western blot","journal":"Aging cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter validation of direct miRNA-target relationship, overexpression rescue, in vivo mouse validation, SMAD2-dependence established; single lab","pmids":["41367311"],"is_preprint":false}],"current_model":"STX6 (syntaxin-6) is a Golgi/endosomal SNARE protein that functions in multiple membrane trafficking pathways: it forms a Q-SNARE complex with STX7 and VTI1B (pairing with R-SNARE VAMP4) to mediate Golgi-to-late-endosome transport; it forms a complex with VTI1B and VAMP3 to fuse recycling endosomes with autophagosomes during xenophagy; and at the Golgi it partners with CAL and recruits MARCH2 E3 ubiquitin ligase to ubiquitinate and direct CFTR to lysosomal degradation. Additional evidence implicates STX6 in prion disease pathogenesis (endosome-to-TGN retrograde transport context), p53-dependent proliferation control via integrin trafficking, and regulation of endothelial cell senescence through the SMAD2/p15 pathway downstream of miR-375-3p."},"narrative":{"mechanistic_narrative":"STX6 (syntaxin-6) is a Q-SNARE protein that mediates membrane fusion across multiple Golgi and endosomal trafficking pathways [PMID:37996040, PMID:34476885]. As a core fusogen it assembles a Q-SNARE complex with STX7 and VTI1B that pairs with the R-SNARE VAMP4 on Golgi-derived vesicles to drive their fusion with late endosomes, a route that controls delivery of MT1-MMP to the cell surface and consequent matrix degradation in activated macrophages [PMID:34476885]. In a distinct fusion event, STX6 is recruited to GAS-containing autophagosome-like vacuoles through its tyrosine-based sorting motif and transmembrane domain, where it forms a SNARE complex with VTI1B and VAMP3 to fuse recycling endosomes with these vacuoles during xenophagy of Group A Streptococcus, a step dependent on RABGEF1 [PMID:27791468]. Beyond its fusogenic role, at the Golgi STX6 forms a complex with CAL and CFTR and recruits the E3 ubiquitin ligase MARCH2, synergistically enhancing MARCH2 binding to CAL to drive ubiquitination and lysosomal degradation of mature CFTR [PMID:23818989]. Genetic ablation of Stx6 in mice modestly prolongs prion disease incubation, consistent with a function in early-endosome-to-trans-Golgi-network retrograde transport relevant to prion pathogenesis, while leaving animals otherwise viable and unimpaired [PMID:37996040]. Additional cellular roles include support of cancer cell proliferation and integrin trafficking [PMID:26906622] and, as a direct target of miR-375-3p, restraint of endothelial cell senescence via the SMAD2/p15 pathway [PMID:41367311].","teleology":[{"year":2013,"claim":"Established that STX6 acts beyond vesicle fusion by serving as a scaffold that couples an E3 ligase to a cargo at the Golgi, defining a route for CFTR quality-control degradation.","evidence":"Reciprocal Co-IP, in vivo ubiquitination assay, siRNA knockdown, and catalytic/PDZ-motif mutants in cells","pmids":["23818989"],"confidence":"High","gaps":["Whether STX6's SNARE/fusion activity is required for the MARCH2-CAL-CFTR scaffolding role is not separated","Structural basis of STX6-driven enhancement of MARCH2-CAL binding unresolved"]},{"year":2016,"claim":"Showed STX6 directs a specific fusion event in antibacterial autophagy, defining the SNARE partners and recruitment determinants that fuse recycling endosomes with pathogen-containing vacuoles.","evidence":"Knockout/knockdown with xenophagy phenotype, Co-IP, domain mutant analysis, live imaging, RABGEF1 epistasis","pmids":["27791468"],"confidence":"High","gaps":["Mechanism by which RABGEF1 promotes assembly of the STX6-VAMP3-VTI1B complex not detailed","Generality of this SNARE set beyond Group A Streptococcus xenophagy unknown"]},{"year":2016,"claim":"Linked STX6 to cancer cell proliferation and migration, implicating it in p53-dependent growth control and integrin trafficking.","evidence":"siRNA silencing with viability, proliferation, integrin trafficking, and migration assays in ESCC cells","pmids":["26906622"],"confidence":"Low","gaps":["KD phenotype without detailed pathway mechanistic validation; integrin-trafficking link stated but not deeply characterized","How STX6 connects mechanistically to p53 is undefined","Single lab, single cancer model"]},{"year":2021,"claim":"Defined the trans-SNARE pairing (STX6/STX7/VTI1B with VAMP4) for Golgi-to-late-endosome fusion and tied it to a functional cargo output, surface MT1-MMP and matrix degradation.","evidence":"Fixed/live imaging, siRNA depletion with gelatin degradation readout, overexpression rescue in LPS-activated macrophages","pmids":["34476885"],"confidence":"Medium","gaps":["Single lab with two orthogonal methods; not independently reconstituted","Regulation of complex assembly in response to LPS not resolved"]},{"year":2023,"claim":"Tested the physiological requirement for STX6 in vivo, showing it is dispensable for development but modulates prion disease progression, consistent with its retrograde transport role.","evidence":"Stx6 knockout mouse, RML/ME7 prion inoculation, histopathology","pmids":["37996040"],"confidence":"Medium","gaps":["Modest effect size (~12 day extension) from a single study","Direct molecular link between STX6 retrograde transport and prion propagation not established"]},{"year":2025,"claim":"Positioned STX6 as a miRNA-regulated node controlling endothelial senescence, identifying it as a direct miR-375-3p target acting through SMAD2/p15.","evidence":"Luciferase 3'UTR reporter, STX6 overexpression rescue, ApoE-/- mouse with miR-375-3p inhibition, SA-β-gal and Western blot","pmids":["41367311"],"confidence":"Medium","gaps":["How STX6 trafficking activity mechanistically couples to SMAD2/p15 signaling is unspecified","Single lab"]},{"year":null,"claim":"How STX6's diverse fusion and scaffolding activities are spatially and temporally partitioned among its distinct SNARE partners and cargoes remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of STX6 trans-SNARE complexes in the corpus","Determinants selecting between STX7/VTI1B/VAMP4 versus VTI1B/VAMP3 partnerships unknown","Mechanism connecting trafficking activity to downstream signaling outcomes (p53, SMAD2/p15) uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,3]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,2]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[1]}],"complexes":["STX6-STX7-VTI1B Q-SNARE complex","STX6-VTI1B-VAMP3 SNARE complex","STX6-CAL-CFTR-MARCH2 complex"],"partners":["STX7","VTI1B","VAMP4","VAMP3","CFTR","MARCH2","RABGEF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43752","full_name":"Syntaxin-6","aliases":[],"length_aa":255,"mass_kda":29.2,"function":"SNARE promoting movement of transport vesicles to target membranes. Targets endosomes to the trans-Golgi network, and may therefore function in retrograde trafficking. Together with SNARE STX12, promotes movement of vesicles from endosomes to the cell membrane, and may therefore function in the endocytic recycling pathway","subcellular_location":"Golgi apparatus membrane; Golgi apparatus, trans-Golgi network membrane; Recycling endosome membrane","url":"https://www.uniprot.org/uniprotkb/O43752/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/STX6","classification":"Not Classified","n_dependent_lines":7,"n_total_lines":1208,"dependency_fraction":0.005794701986754967},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000135823","cell_line_id":"CID000761","localizations":[{"compartment":"vesicles","grade":3}],"interactors":[{"gene":"VTI1A","stoichiometry":10.0},{"gene":"STX16","stoichiometry":4.0},{"gene":"STX16;STX16-NPEPL1","stoichiometry":4.0},{"gene":"VPS45","stoichiometry":4.0},{"gene":"NAPA","stoichiometry":0.2},{"gene":"STX12","stoichiometry":0.2},{"gene":"SNAP23","stoichiometry":0.2},{"gene":"NSF","stoichiometry":0.2},{"gene":"PTTG1IP","stoichiometry":0.2},{"gene":"OSBPL6","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000761","total_profiled":1310},"omim":[{"mim_id":"620986","title":"T-SNARE DOMAIN-CONTAINING PROTEIN 1; TSNARE1","url":"https://www.omim.org/entry/620986"},{"mim_id":"619811","title":"UHRF1-BINDING PROTEIN 1-LIKE; UHRF1BP1L","url":"https://www.omim.org/entry/619811"},{"mim_id":"615850","title":"VPS53 SUBUNIT OF GARP COMPLEX; VPS53","url":"https://www.omim.org/entry/615850"},{"mim_id":"615738","title":"VPS51 SUBUNIT OF GARP COMPLEX; VPS51","url":"https://www.omim.org/entry/615738"},{"mim_id":"615328","title":"SHAHEEN SYNDROME; SHNS","url":"https://www.omim.org/entry/615328"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/STX6"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O43752","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43752","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43752-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43752-F1-predicted_aligned_error_v6.png","plddt_mean":81.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=STX6","jax_strain_url":"https://www.jax.org/strain/search?query=STX6"},"sequence":{"accession":"O43752","fasta_url":"https://rest.uniprot.org/uniprotkb/O43752.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43752/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43752"}},"corpus_meta":[{"pmid":"23116876","id":"PMC_23116876","title":"An exploratory study on STX6, MOBP, MAPT, and EIF2AK3 and late-onset Alzheimer's disease.","date":"2012","source":"Neurobiology of aging","url":"https://pubmed.ncbi.nlm.nih.gov/23116876","citation_count":49,"is_preprint":false},{"pmid":"23818989","id":"PMC_23818989","title":"Ubiquitination and degradation of CFTR by the E3 ubiquitin ligase MARCH2 through its association with adaptor proteins CAL and STX6.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23818989","citation_count":49,"is_preprint":false},{"pmid":"27791468","id":"PMC_27791468","title":"The STX6-VTI1B-VAMP3 complex facilitates xenophagy by regulating the fusion between recycling endosomes and autophagosomes.","date":"2016","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/27791468","citation_count":39,"is_preprint":false},{"pmid":"32274658","id":"PMC_32274658","title":"Circular RNA hsa_circ_0002052 promotes osteosarcoma via modulating miR-382/STX6 axis.","date":"2020","source":"Human cell","url":"https://pubmed.ncbi.nlm.nih.gov/32274658","citation_count":27,"is_preprint":false},{"pmid":"26906622","id":"PMC_26906622","title":"Essential role of STX6 in esophageal squamous cell carcinoma growth and migration.","date":"2016","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/26906622","citation_count":18,"is_preprint":false},{"pmid":"23415606","id":"PMC_23415606","title":"STX6 rs1411478 is not associated with increased risk of Parkinson's disease.","date":"2013","source":"Parkinsonism & related disorders","url":"https://pubmed.ncbi.nlm.nih.gov/23415606","citation_count":15,"is_preprint":false},{"pmid":"34476885","id":"PMC_34476885","title":"The trans-SNARE complex VAMP4/Stx6/Stx7/Vti1b is a key regulator of Golgi to late endosome MT1-MMP transport in macrophages.","date":"2021","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/34476885","citation_count":12,"is_preprint":false},{"pmid":"37996040","id":"PMC_37996040","title":"Characterisation and prion transmission study in mice with genetic reduction of sporadic Creutzfeldt-Jakob disease risk gene Stx6.","date":"2023","source":"Neurobiology of disease","url":"https://pubmed.ncbi.nlm.nih.gov/37996040","citation_count":11,"is_preprint":false},{"pmid":"38505873","id":"PMC_38505873","title":"KDM4A-AS1 Promotes Cell Proliferation, Migration, and Invasion via the miR-4306/STX6 Axis in Hepatocellular Carcinoma.","date":"2024","source":"Critical reviews in eukaryotic gene expression","url":"https://pubmed.ncbi.nlm.nih.gov/38505873","citation_count":4,"is_preprint":false},{"pmid":"40618089","id":"PMC_40618089","title":"DNA methylation as a contributor to dysregulation of STX6 and other frontotemporal Lobar degeneration genetic risk-associated loci.","date":"2025","source":"Acta neuropathologica communications","url":"https://pubmed.ncbi.nlm.nih.gov/40618089","citation_count":3,"is_preprint":false},{"pmid":"39975316","id":"PMC_39975316","title":"DNA methylation as a contributor to dysregulation of STX6 and other frontotemporal lobar degeneration genetic risk-associated loci.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39975316","citation_count":1,"is_preprint":false},{"pmid":"41367311","id":"PMC_41367311","title":"miR-375-3p/STX6 Exacerbates Atherosclerosis by Promoting Endothelial Cell Senescence via Activation of TGF-Beta Signals.","date":"2025","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/41367311","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.01.21.634065","title":"DNA methylation as a contributor to dysregulation of  <i>STX6</i>  and other frontotemporal lobar degeneration genetic risk-associated 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Genes","date":"2024-07-21","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.19.24310476","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10523,"output_tokens":1847,"usd":0.029637,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8636,"output_tokens":2776,"usd":0.05629,"stage2_stop_reason":"end_turn"},"total_usd":0.085927,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"STX6 forms a complex with CAL (CFTR-associated ligand) and CFTR at the Golgi, and recruits the E3 ubiquitin ligase MARCH2 to this complex; STX6 synergistically enhances MARCH2 binding to CAL, leading to MARCH2-mediated ubiquitination and lysosomal degradation of mature CFTR.\",\n      \"method\": \"Co-immunoprecipitation, co-localization, in vivo ubiquitination assay, siRNA knockdown, overexpression with catalytically dead RING mutant and PDZ-motif CFTR mutant\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, multiple orthogonal approaches (ubiquitination assay, catalytic mutant, PDZ mutant, siRNA), rigorous controls in single study\",\n      \"pmids\": [\"23818989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"STX6 is recruited to GAS-containing autophagosome-like vacuoles (GcAVs) via its tyrosine-based sorting motif and transmembrane domain, where it forms a SNARE complex with VTI1B and VAMP3 to drive fusion between recycling endosomes and GcAVs, thereby promoting xenophagy of Group A Streptococcus. RABGEF1 mediates this RE-GcAV fusion through the STX6-VAMP3-VTI1B complex.\",\n      \"method\": \"Knockdown and knockout experiments, co-immunoprecipitation, co-localization with transferrin receptor-positive puncta, domain mutant analysis, live-cell imaging\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO/KD with defined phenotype, Co-IP, domain mutant analysis, and epistasis with RABGEF1 in a single rigorous study\",\n      \"pmids\": [\"27791468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"STX6 forms a trans-SNARE Q-SNARE complex with STX7 and VTI1B that pairs with the R-SNARE VAMP4 on Golgi-derived vesicles to mediate fusion with late endosomes, regulating transport of MT1-MMP to the cell surface in LPS-activated macrophages. Depletion of STX6 reduces surface MT1-MMP and gelatin degradation; overexpression of the Stx6/Stx7/Vti1b complex increases surface MT1-MMP.\",\n      \"method\": \"Fixed and live imaging, siRNA depletion with functional readout (gelatin degradation assay), overexpression rescue\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with defined functional readout (degradation assay) and overexpression rescue, single lab, two orthogonal methods\",\n      \"pmids\": [\"34476885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"STX6 is primarily involved in early endosome to trans-Golgi network retrograde transport. Genetic knockout of Stx6 in mice modestly extended prion disease incubation periods (by ~12 days) following RML or ME7 prion inoculation, suggesting a functional role in prion pathogenesis. Stx6-/- mice are viable and fertile with no gross neurological, biochemical, or skeletal impairments under non-disease conditions.\",\n      \"method\": \"Stx6 knockout mouse model, prion transmission study (inoculation with RML and ME7 prions), histopathological analysis of neuropathology endpoints\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined in vivo phenotypic readout, but modest effect size and single study\",\n      \"pmids\": [\"37996040\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"STX6 silencing in esophageal squamous cell carcinoma (ESCC) cells inhibited cell viability and proliferation in a p53-dependent manner, and also impaired integrin trafficking and cell migration.\",\n      \"method\": \"siRNA silencing, cell viability and proliferation assays, integrin trafficking assay, migration assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, KD phenotype without detailed pathway mechanistic validation; integrin trafficking link stated but not deeply characterized\",\n      \"pmids\": [\"26906622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"STX6 is a direct target of miR-375-3p; overexpression of STX6 rescued endothelial cell senescence phenotypes (SA-β-gal staining, p15/IL6/IL8 upregulation) induced by miR-375-3p. Mechanistically, the miR-375-3p/STX6 axis promotes endothelial cell senescence and atherosclerosis via the SMAD2/p15 pathway in a SMAD2-dependent manner.\",\n      \"method\": \"Luciferase reporter assay (miR-375-3p targeting STX6 3'UTR), STX6 overexpression rescue, in vivo ApoE-/- mouse model with miR-375-3p inhibition, SA-β-gal staining, Western blot\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter validation of direct miRNA-target relationship, overexpression rescue, in vivo mouse validation, SMAD2-dependence established; single lab\",\n      \"pmids\": [\"41367311\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STX6 (syntaxin-6) is a Golgi/endosomal SNARE protein that functions in multiple membrane trafficking pathways: it forms a Q-SNARE complex with STX7 and VTI1B (pairing with R-SNARE VAMP4) to mediate Golgi-to-late-endosome transport; it forms a complex with VTI1B and VAMP3 to fuse recycling endosomes with autophagosomes during xenophagy; and at the Golgi it partners with CAL and recruits MARCH2 E3 ubiquitin ligase to ubiquitinate and direct CFTR to lysosomal degradation. Additional evidence implicates STX6 in prion disease pathogenesis (endosome-to-TGN retrograde transport context), p53-dependent proliferation control via integrin trafficking, and regulation of endothelial cell senescence through the SMAD2/p15 pathway downstream of miR-375-3p.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"STX6 (syntaxin-6) is a Q-SNARE protein that mediates membrane fusion across multiple Golgi and endosomal trafficking pathways [#3, #2]. As a core fusogen it assembles a Q-SNARE complex with STX7 and VTI1B that pairs with the R-SNARE VAMP4 on Golgi-derived vesicles to drive their fusion with late endosomes, a route that controls delivery of MT1-MMP to the cell surface and consequent matrix degradation in activated macrophages [#2]. In a distinct fusion event, STX6 is recruited to GAS-containing autophagosome-like vacuoles through its tyrosine-based sorting motif and transmembrane domain, where it forms a SNARE complex with VTI1B and VAMP3 to fuse recycling endosomes with these vacuoles during xenophagy of Group A Streptococcus, a step dependent on RABGEF1 [#1]. Beyond its fusogenic role, at the Golgi STX6 forms a complex with CAL and CFTR and recruits the E3 ubiquitin ligase MARCH2, synergistically enhancing MARCH2 binding to CAL to drive ubiquitination and lysosomal degradation of mature CFTR [#0]. Genetic ablation of Stx6 in mice modestly prolongs prion disease incubation, consistent with a function in early-endosome-to-trans-Golgi-network retrograde transport relevant to prion pathogenesis, while leaving animals otherwise viable and unimpaired [#3]. Additional cellular roles include support of cancer cell proliferation and integrin trafficking [#4] and, as a direct target of miR-375-3p, restraint of endothelial cell senescence via the SMAD2/p15 pathway [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established that STX6 acts beyond vesicle fusion by serving as a scaffold that couples an E3 ligase to a cargo at the Golgi, defining a route for CFTR quality-control degradation.\",\n      \"evidence\": \"Reciprocal Co-IP, in vivo ubiquitination assay, siRNA knockdown, and catalytic/PDZ-motif mutants in cells\",\n      \"pmids\": [\"23818989\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether STX6's SNARE/fusion activity is required for the MARCH2-CAL-CFTR scaffolding role is not separated\",\n        \"Structural basis of STX6-driven enhancement of MARCH2-CAL binding unresolved\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed STX6 directs a specific fusion event in antibacterial autophagy, defining the SNARE partners and recruitment determinants that fuse recycling endosomes with pathogen-containing vacuoles.\",\n      \"evidence\": \"Knockout/knockdown with xenophagy phenotype, Co-IP, domain mutant analysis, live imaging, RABGEF1 epistasis\",\n      \"pmids\": [\"27791468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which RABGEF1 promotes assembly of the STX6-VAMP3-VTI1B complex not detailed\",\n        \"Generality of this SNARE set beyond Group A Streptococcus xenophagy unknown\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked STX6 to cancer cell proliferation and migration, implicating it in p53-dependent growth control and integrin trafficking.\",\n      \"evidence\": \"siRNA silencing with viability, proliferation, integrin trafficking, and migration assays in ESCC cells\",\n      \"pmids\": [\"26906622\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"KD phenotype without detailed pathway mechanistic validation; integrin-trafficking link stated but not deeply characterized\",\n        \"How STX6 connects mechanistically to p53 is undefined\",\n        \"Single lab, single cancer model\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined the trans-SNARE pairing (STX6/STX7/VTI1B with VAMP4) for Golgi-to-late-endosome fusion and tied it to a functional cargo output, surface MT1-MMP and matrix degradation.\",\n      \"evidence\": \"Fixed/live imaging, siRNA depletion with gelatin degradation readout, overexpression rescue in LPS-activated macrophages\",\n      \"pmids\": [\"34476885\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab with two orthogonal methods; not independently reconstituted\",\n        \"Regulation of complex assembly in response to LPS not resolved\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Tested the physiological requirement for STX6 in vivo, showing it is dispensable for development but modulates prion disease progression, consistent with its retrograde transport role.\",\n      \"evidence\": \"Stx6 knockout mouse, RML/ME7 prion inoculation, histopathology\",\n      \"pmids\": [\"37996040\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Modest effect size (~12 day extension) from a single study\",\n        \"Direct molecular link between STX6 retrograde transport and prion propagation not established\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Positioned STX6 as a miRNA-regulated node controlling endothelial senescence, identifying it as a direct miR-375-3p target acting through SMAD2/p15.\",\n      \"evidence\": \"Luciferase 3'UTR reporter, STX6 overexpression rescue, ApoE-/- mouse with miR-375-3p inhibition, SA-β-gal and Western blot\",\n      \"pmids\": [\"41367311\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"How STX6 trafficking activity mechanistically couples to SMAD2/p15 signaling is unspecified\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How STX6's diverse fusion and scaffolding activities are spatially and temporally partitioned among its distinct SNARE partners and cargoes remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of STX6 trans-SNARE complexes in the corpus\",\n        \"Determinants selecting between STX7/VTI1B/VAMP4 versus VTI1B/VAMP3 partnerships unknown\",\n        \"Mechanism connecting trafficking activity to downstream signaling outcomes (p53, SMAD2/p15) uncharacterized\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\n      \"STX6-STX7-VTI1B Q-SNARE complex\",\n      \"STX6-VTI1B-VAMP3 SNARE complex\",\n      \"STX6-CAL-CFTR-MARCH2 complex\"\n    ],\n    \"partners\": [\n      \"STX7\",\n      \"VTI1B\",\n      \"VAMP4\",\n      \"VAMP3\",\n      \"CFTR\",\n      \"MARCH2\",\n      \"RABGEF1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}