{"gene":"STON2","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2013,"finding":"Deletion of stonin 2 (Stn2) in mice causes selective missorting of synaptotagmin 1 (Syt1) to the neuronal surface, elevated SV pool size, and accelerated SV protein endocytosis, demonstrating that Stn2 is required for fidelity of synaptic vesicle (SV) protein sorting but dispensable for the speed of SV recycling. Loss of Stn2 correlates with up-regulation of SV reformation from bulk endosomes.","method":"Genetic knockout in mice, live imaging, FM dye assays, immunostaining of SV proteins at neuronal surface","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout mouse model with multiple orthogonal readouts (surface missorting, pool size, endocytosis speed), replicated phenotypes across assays","pmids":["23345427"],"is_preprint":false},{"year":2015,"finding":"Endocytic sorting of synaptotagmin 1 (Syt1) to synaptic vesicles is mediated by the overlapping activities of the Syt1-associated SV glycoprotein SV2A/B and the endocytic adaptor stonin 2 (Stn2). Deletion of either alone causes partial Syt1 missorting; deletion of both dramatically exacerbates Syt1 loss and impairs neurotransmission efficacy at hippocampal synapses.","method":"Genetic knockout and knockdown (single and double) in mice/neurons, immunostaining, electrophysiology at hippocampal synapses","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double-mutant rescue/exacerbation, multiple orthogonal methods, independent of prior knockout study","pmids":["26015569"],"is_preprint":false},{"year":2024,"finding":"Schizophrenia-associated STON2 variants (307Pro-851Ala haplotype) cause protein dephosphorylation that impairs STON2's interaction with synaptotagmin 1 (Syt1), disrupting clathrin-mediated endocytosis (CME) of synaptic vesicles. STON2307Pro851Ala knockin mice exhibit deficits in synaptic transmission, short-term plasticity, and schizophrenia-like behaviors. Acute haloperidol administration recovers Syt1 sorting and synaptic transmission deficits in knockin mice.","method":"Knockin mouse model (STON2307Pro851Ala), co-immunoprecipitation, synaptic transmission electrophysiology, behavioral assays, pharmacological rescue with haloperidol","journal":"Science bulletin","confidence":"High","confidence_rationale":"Tier 2 / Strong — knockin mouse model with multiple orthogonal methods (Co-IP for interaction, electrophysiology, behavior, pharmacological rescue)","pmids":["38402028"],"is_preprint":false},{"year":2018,"finding":"STON2 knockdown in ovarian cancer cells increases MUC1 expression via decreased DNMT1 expression and reduced methylation of the MUC1 promoter, and STON2 overexpression suppresses MUC1-induced sphere formation of ovarian cancer stem cells, placing STON2 upstream of a DNMT1/MUC1 epigenetic axis that regulates stem-like properties.","method":"siRNA knockdown and overexpression, RNA-seq, pyrosequencing of MUC1 promoter methylation, western blotting, sphere-forming assays, xenograft mouse model","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (methylation sequencing, western blot, functional rescue), single lab","pmids":["30518424"],"is_preprint":false},{"year":2023,"finding":"In oral cancer cells, STON2 maintains lysosomal membrane integrity and activates the Akt-mTOR axis, retaining mTOR on lysosomal membranes. STON2 overexpression restores lysosomal activity and Akt-mTOR expression in cells treated with the STON2 inhibitor trifluoperazine dihydrochloride (TFP), which causes lysosomal membrane permeabilization by disrupting this pathway.","method":"STON2 overexpression and inhibitor treatment (TFP), western blotting for Akt-mTOR pathway components, lysosomal membrane integrity assays, cell viability assays","journal":"Toxicology in vitro : an international journal published in association with BIBRA","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, primarily overexpression + pharmacological inhibitor without rigorous mechanistic dissection of direct vs. indirect effects","pmids":["36702439"],"is_preprint":false},{"year":2018,"finding":"STON2 is a direct target gene of miR-199b-5p in papillary thyroid carcinoma; miR-199b-5p suppresses tumor cell growth, migration, invasion, and EMT by downregulating STON2, and STON2 overexpression reverses the tumor-suppressive effects of miR-199b-5p.","method":"Dual-luciferase reporter assay confirming direct miR-199b-5p binding to STON2 3'UTR, overexpression and knockdown in B-CPAP cells, in vivo xenograft","journal":"IUBMB life","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — luciferase reporter validates direct targeting, multiple functional assays and in vivo rescue, single lab","pmids":["30325582"],"is_preprint":false},{"year":2022,"finding":"miR-144-5p directly down-regulates STON2 expression (validated by dual-luciferase reporter assay), and STON2 overexpression reverses the inhibitory effects of miR-144-5p on thyroid carcinoma cell viability, proliferation, migration, and invasion, as well as on EMT marker expression (E-cadherin, MMP-9, N-cadherin).","method":"Dual-luciferase reporter assay, qRT-PCR, western blotting, overexpression rescue experiments, xenograft mouse model","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, overlapping with miR-199b-5p finding; direct STON2 mechanism in cancer not mechanistically distinct","pmids":["35184686"],"is_preprint":false},{"year":2020,"finding":"The lncRNA GACAT1 adsorbs miR-875-3p (sponge), relieving repression of STON2 (validated as a direct miR-875-3p target by dual-luciferase reporter assay); STON2 overexpression partially rescues proliferation inhibited by miR-875-3p in breast cancer cells.","method":"Dual-luciferase reporter assay for miR-875-3p/STON2 interaction, qRT-PCR, overexpression rescue assays in MCF-7 and BCap-37 cells","journal":"Oncology letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, STON2 is a secondary target in a lncRNA study; mechanistic dissection of STON2's role is limited","pmids":["32194758"],"is_preprint":false}],"current_model":"STON2 (stonin 2) functions as a clathrin-mediated endocytic adaptor at presynaptic terminals that directly binds synaptotagmin 1 (Syt1) — an interaction regulated by phosphorylation — to sort Syt1 back to synaptic vesicles after exocytosis; loss of STON2 causes selective surface missorting of Syt1 (partially compensated by SV2A/B), impairs synaptic transmission and short-term plasticity, and schizophrenia-associated STON2 variants that disrupt this interaction produce synaptic dysfunction and schizophrenia-like behaviors in knockin mice, while in cancer contexts STON2 additionally modulates a DNMT1/MUC1 epigenetic axis and a lysosomal Akt-mTOR pathway."},"narrative":{"mechanistic_narrative":"STON2 (stonin 2) is a clathrin-mediated endocytic adaptor that ensures the fidelity of synaptic vesicle (SV) protein sorting at presynaptic terminals [PMID:23345427]. Genetic deletion in mice causes selective missorting of synaptotagmin 1 (Syt1) to the neuronal surface and an enlarged SV pool, while leaving the overall speed of SV recycling intact — establishing STON2 as a sorting fidelity factor rather than a rate-limiting endocytic component [PMID:23345427]. STON2 acts in parallel with the Syt1-associated SV glycoprotein SV2A/B: loss of either alone produces partial Syt1 missorting, whereas combined loss dramatically exacerbates Syt1 depletion and impairs neurotransmission at hippocampal synapses [PMID:26015569]. The retrieval of Syt1 depends on a direct STON2–Syt1 interaction controlled by STON2 phosphorylation; schizophrenia-associated STON2 variants (307Pro-851Ala) are dephosphorylated, weakening Syt1 binding and disrupting SV endocytosis, and knockin mice carrying these variants display deficits in synaptic transmission, short-term plasticity, and schizophrenia-like behaviors that are reversed by haloperidol [PMID:38402028]. Beyond its synaptic role, STON2 has been linked in cancer cells to a DNMT1/MUC1 epigenetic axis governing stem-like properties [PMID:30518424] and is itself a direct target of multiple microRNAs that regulate proliferation and EMT [PMID:30325582].","teleology":[{"year":2013,"claim":"Established that STON2 is required for accurate sorting of SV proteins rather than for the speed of vesicle recycling, defining its core function as a fidelity factor in synaptic vesicle protein retrieval.","evidence":"Stn2 knockout mice with live imaging, FM dye assays, and surface immunostaining of SV proteins","pmids":["23345427"],"confidence":"High","gaps":["Did not resolve the direct molecular binding interface mediating Syt1 selectivity","Mechanism of the observed up-regulation of bulk endosome SV reformation not defined"]},{"year":2015,"claim":"Resolved whether STON2 acts alone in Syt1 sorting by showing it operates in parallel with SV2A/B, with the two providing overlapping retrieval activity that converges on neurotransmission efficacy.","evidence":"Single and double genetic knockout/knockdown in mice and neurons, immunostaining, and hippocampal electrophysiology","pmids":["26015569"],"confidence":"High","gaps":["Did not establish whether STON2 and SV2A/B engage Syt1 at distinct sites or compete","Structural basis of the redundancy unresolved"]},{"year":2024,"claim":"Connected STON2 phosphorylation state to the strength of the Syt1 interaction and to human disease, showing dephosphorylated schizophrenia-associated variants impair Syt1 retrieval and cause schizophrenia-like phenotypes reversible by haloperidol.","evidence":"STON2(307Pro851Ala) knockin mouse, co-immunoprecipitation, synaptic electrophysiology, behavioral assays, and pharmacological rescue","pmids":["38402028"],"confidence":"High","gaps":["Identity of the kinase/phosphatase controlling STON2 phosphorylation not defined","Mechanism by which haloperidol restores Syt1 sorting not established"]},{"year":2018,"claim":"Extended STON2 function beyond the synapse by placing it upstream of a DNMT1/MUC1 epigenetic axis that controls cancer stem-like properties.","evidence":"siRNA knockdown/overexpression in ovarian cancer cells with RNA-seq, MUC1 promoter pyrosequencing, sphere-forming assays, and xenografts","pmids":["30518424"],"confidence":"Medium","gaps":["Whether STON2 regulates DNMT1 directly or indirectly not resolved","Connection between endocytic adaptor activity and epigenetic regulation unexplained"]},{"year":2018,"claim":"Identified STON2 as a direct miRNA target, with miR-199b-5p suppression of STON2 modulating tumor cell growth, migration, invasion, and EMT.","evidence":"Dual-luciferase reporter validation of miR-199b-5p binding to STON2 3'UTR, overexpression/knockdown in B-CPAP cells, and xenografts","pmids":["30325582"],"confidence":"Medium","gaps":["Downstream effectors of STON2 in thyroid carcinoma not defined","Whether STON2's pro-tumor role uses its endocytic activity unknown"]},{"year":2020,"claim":"Positioned STON2 within a competing-endogenous-RNA network as a downstream node of an lncRNA GACAT1/miR-875-3p axis in breast cancer proliferation.","evidence":"Dual-luciferase reporter for miR-875-3p/STON2, qRT-PCR, and overexpression rescue in MCF-7 and BCap-37 cells","pmids":["32194758"],"confidence":"Low","gaps":["STON2 is a secondary target in the lncRNA study with limited mechanistic dissection","Direct functional role of STON2 in breast cancer not isolated"]},{"year":2022,"claim":"Reinforced miRNA regulation of STON2 by showing miR-144-5p directly downregulates STON2 to control thyroid carcinoma proliferation and EMT.","evidence":"Dual-luciferase reporter, qRT-PCR, western blot, and overexpression rescue with xenografts","pmids":["35184686"],"confidence":"Low","gaps":["Single lab and mechanistically overlapping with prior miRNA findings","Molecular mechanism downstream of STON2 not distinct from earlier reports"]},{"year":2023,"claim":"Linked STON2 to lysosomal membrane integrity and Akt-mTOR signaling in oral cancer cells, suggesting a membrane-trafficking role beyond the synapse.","evidence":"STON2 overexpression with TFP inhibitor treatment, western blots for Akt-mTOR, and lysosomal integrity and viability assays","pmids":["36702439"],"confidence":"Low","gaps":["Primarily overexpression plus pharmacological inhibitor without dissection of direct vs. indirect effects","Whether STON2 physically associates with the lysosomal membrane or mTOR machinery untested"]},{"year":null,"claim":"How STON2's defined presynaptic endocytic adaptor activity relates mechanistically to its reported roles in cancer epigenetics and lysosomal signaling remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of the STON2-Syt1 interface","Kinase/phosphatase regulating STON2 phosphorylation unidentified","No unifying mechanism connecting synaptic and cancer functions"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2]}],"localization":[],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,1,2]}],"complexes":[],"partners":["SYT1","SV2A","SV2B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8WXE9","full_name":"Stonin-2","aliases":["Stoned B"],"length_aa":905,"mass_kda":101.2,"function":"Adapter protein involved in endocytic machinery. Involved in the synaptic vesicle recycling. May facilitate clathrin-coated vesicle uncoating","subcellular_location":"Cytoplasm; Membrane; Synapse, synaptosome","url":"https://www.uniprot.org/uniprotkb/Q8WXE9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/STON2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/STON2","total_profiled":1310},"omim":[{"mim_id":"608467","title":"STONIN 2; STON2","url":"https://www.omim.org/entry/608467"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":30.4}],"url":"https://www.proteinatlas.org/search/STON2"},"hgnc":{"alias_symbol":["STNB2","STN2"],"prev_symbol":[]},"alphafold":{"accession":"Q8WXE9","domains":[{"cath_id":"2.30.29.30","chopping":"424-553","consensus_level":"medium","plddt":89.1542,"start":424,"end":553},{"cath_id":"2.60.40.1170","chopping":"563-683_842-868","consensus_level":"medium","plddt":92.2331,"start":563,"end":868},{"cath_id":"2.60.40.1170","chopping":"689-839_876-904","consensus_level":"high","plddt":76.1935,"start":689,"end":904}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WXE9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WXE9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WXE9-F1-predicted_aligned_error_v6.png","plddt_mean":61.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=STON2","jax_strain_url":"https://www.jax.org/strain/search?query=STON2"},"sequence":{"accession":"Q8WXE9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8WXE9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8WXE9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WXE9"}},"corpus_meta":[{"pmid":"23345427","id":"PMC_23345427","title":"Compromised 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Loss of Stn2 correlates with up-regulation of SV reformation from bulk endosomes.\",\n      \"method\": \"Genetic knockout in mice, live imaging, FM dye assays, immunostaining of SV proteins at neuronal surface\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout mouse model with multiple orthogonal readouts (surface missorting, pool size, endocytosis speed), replicated phenotypes across assays\",\n      \"pmids\": [\"23345427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Endocytic sorting of synaptotagmin 1 (Syt1) to synaptic vesicles is mediated by the overlapping activities of the Syt1-associated SV glycoprotein SV2A/B and the endocytic adaptor stonin 2 (Stn2). Deletion of either alone causes partial Syt1 missorting; deletion of both dramatically exacerbates Syt1 loss and impairs neurotransmission efficacy at hippocampal synapses.\",\n      \"method\": \"Genetic knockout and knockdown (single and double) in mice/neurons, immunostaining, electrophysiology at hippocampal synapses\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double-mutant rescue/exacerbation, multiple orthogonal methods, independent of prior knockout study\",\n      \"pmids\": [\"26015569\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Schizophrenia-associated STON2 variants (307Pro-851Ala haplotype) cause protein dephosphorylation that impairs STON2's interaction with synaptotagmin 1 (Syt1), disrupting clathrin-mediated endocytosis (CME) of synaptic vesicles. STON2307Pro851Ala knockin mice exhibit deficits in synaptic transmission, short-term plasticity, and schizophrenia-like behaviors. Acute haloperidol administration recovers Syt1 sorting and synaptic transmission deficits in knockin mice.\",\n      \"method\": \"Knockin mouse model (STON2307Pro851Ala), co-immunoprecipitation, synaptic transmission electrophysiology, behavioral assays, pharmacological rescue with haloperidol\",\n      \"journal\": \"Science bulletin\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knockin mouse model with multiple orthogonal methods (Co-IP for interaction, electrophysiology, behavior, pharmacological rescue)\",\n      \"pmids\": [\"38402028\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"STON2 knockdown in ovarian cancer cells increases MUC1 expression via decreased DNMT1 expression and reduced methylation of the MUC1 promoter, and STON2 overexpression suppresses MUC1-induced sphere formation of ovarian cancer stem cells, placing STON2 upstream of a DNMT1/MUC1 epigenetic axis that regulates stem-like properties.\",\n      \"method\": \"siRNA knockdown and overexpression, RNA-seq, pyrosequencing of MUC1 promoter methylation, western blotting, sphere-forming assays, xenograft mouse model\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (methylation sequencing, western blot, functional rescue), single lab\",\n      \"pmids\": [\"30518424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In oral cancer cells, STON2 maintains lysosomal membrane integrity and activates the Akt-mTOR axis, retaining mTOR on lysosomal membranes. STON2 overexpression restores lysosomal activity and Akt-mTOR expression in cells treated with the STON2 inhibitor trifluoperazine dihydrochloride (TFP), which causes lysosomal membrane permeabilization by disrupting this pathway.\",\n      \"method\": \"STON2 overexpression and inhibitor treatment (TFP), western blotting for Akt-mTOR pathway components, lysosomal membrane integrity assays, cell viability assays\",\n      \"journal\": \"Toxicology in vitro : an international journal published in association with BIBRA\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, primarily overexpression + pharmacological inhibitor without rigorous mechanistic dissection of direct vs. indirect effects\",\n      \"pmids\": [\"36702439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"STON2 is a direct target gene of miR-199b-5p in papillary thyroid carcinoma; miR-199b-5p suppresses tumor cell growth, migration, invasion, and EMT by downregulating STON2, and STON2 overexpression reverses the tumor-suppressive effects of miR-199b-5p.\",\n      \"method\": \"Dual-luciferase reporter assay confirming direct miR-199b-5p binding to STON2 3'UTR, overexpression and knockdown in B-CPAP cells, in vivo xenograft\",\n      \"journal\": \"IUBMB life\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — luciferase reporter validates direct targeting, multiple functional assays and in vivo rescue, single lab\",\n      \"pmids\": [\"30325582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"miR-144-5p directly down-regulates STON2 expression (validated by dual-luciferase reporter assay), and STON2 overexpression reverses the inhibitory effects of miR-144-5p on thyroid carcinoma cell viability, proliferation, migration, and invasion, as well as on EMT marker expression (E-cadherin, MMP-9, N-cadherin).\",\n      \"method\": \"Dual-luciferase reporter assay, qRT-PCR, western blotting, overexpression rescue experiments, xenograft mouse model\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, overlapping with miR-199b-5p finding; direct STON2 mechanism in cancer not mechanistically distinct\",\n      \"pmids\": [\"35184686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The lncRNA GACAT1 adsorbs miR-875-3p (sponge), relieving repression of STON2 (validated as a direct miR-875-3p target by dual-luciferase reporter assay); STON2 overexpression partially rescues proliferation inhibited by miR-875-3p in breast cancer cells.\",\n      \"method\": \"Dual-luciferase reporter assay for miR-875-3p/STON2 interaction, qRT-PCR, overexpression rescue assays in MCF-7 and BCap-37 cells\",\n      \"journal\": \"Oncology letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, STON2 is a secondary target in a lncRNA study; mechanistic dissection of STON2's role is limited\",\n      \"pmids\": [\"32194758\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STON2 (stonin 2) functions as a clathrin-mediated endocytic adaptor at presynaptic terminals that directly binds synaptotagmin 1 (Syt1) — an interaction regulated by phosphorylation — to sort Syt1 back to synaptic vesicles after exocytosis; loss of STON2 causes selective surface missorting of Syt1 (partially compensated by SV2A/B), impairs synaptic transmission and short-term plasticity, and schizophrenia-associated STON2 variants that disrupt this interaction produce synaptic dysfunction and schizophrenia-like behaviors in knockin mice, while in cancer contexts STON2 additionally modulates a DNMT1/MUC1 epigenetic axis and a lysosomal Akt-mTOR pathway.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"STON2 (stonin 2) is a clathrin-mediated endocytic adaptor that ensures the fidelity of synaptic vesicle (SV) protein sorting at presynaptic terminals [#0]. Genetic deletion in mice causes selective missorting of synaptotagmin 1 (Syt1) to the neuronal surface and an enlarged SV pool, while leaving the overall speed of SV recycling intact — establishing STON2 as a sorting fidelity factor rather than a rate-limiting endocytic component [#0]. STON2 acts in parallel with the Syt1-associated SV glycoprotein SV2A/B: loss of either alone produces partial Syt1 missorting, whereas combined loss dramatically exacerbates Syt1 depletion and impairs neurotransmission at hippocampal synapses [#1]. The retrieval of Syt1 depends on a direct STON2–Syt1 interaction controlled by STON2 phosphorylation; schizophrenia-associated STON2 variants (307Pro-851Ala) are dephosphorylated, weakening Syt1 binding and disrupting SV endocytosis, and knockin mice carrying these variants display deficits in synaptic transmission, short-term plasticity, and schizophrenia-like behaviors that are reversed by haloperidol [#2]. Beyond its synaptic role, STON2 has been linked in cancer cells to a DNMT1/MUC1 epigenetic axis governing stem-like properties [#3] and is itself a direct target of multiple microRNAs that regulate proliferation and EMT [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established that STON2 is required for accurate sorting of SV proteins rather than for the speed of vesicle recycling, defining its core function as a fidelity factor in synaptic vesicle protein retrieval.\",\n      \"evidence\": \"Stn2 knockout mice with live imaging, FM dye assays, and surface immunostaining of SV proteins\",\n      \"pmids\": [\"23345427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not resolve the direct molecular binding interface mediating Syt1 selectivity\",\n        \"Mechanism of the observed up-regulation of bulk endosome SV reformation not defined\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Resolved whether STON2 acts alone in Syt1 sorting by showing it operates in parallel with SV2A/B, with the two providing overlapping retrieval activity that converges on neurotransmission efficacy.\",\n      \"evidence\": \"Single and double genetic knockout/knockdown in mice and neurons, immunostaining, and hippocampal electrophysiology\",\n      \"pmids\": [\"26015569\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not establish whether STON2 and SV2A/B engage Syt1 at distinct sites or compete\",\n        \"Structural basis of the redundancy unresolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected STON2 phosphorylation state to the strength of the Syt1 interaction and to human disease, showing dephosphorylated schizophrenia-associated variants impair Syt1 retrieval and cause schizophrenia-like phenotypes reversible by haloperidol.\",\n      \"evidence\": \"STON2(307Pro851Ala) knockin mouse, co-immunoprecipitation, synaptic electrophysiology, behavioral assays, and pharmacological rescue\",\n      \"pmids\": [\"38402028\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the kinase/phosphatase controlling STON2 phosphorylation not defined\",\n        \"Mechanism by which haloperidol restores Syt1 sorting not established\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Extended STON2 function beyond the synapse by placing it upstream of a DNMT1/MUC1 epigenetic axis that controls cancer stem-like properties.\",\n      \"evidence\": \"siRNA knockdown/overexpression in ovarian cancer cells with RNA-seq, MUC1 promoter pyrosequencing, sphere-forming assays, and xenografts\",\n      \"pmids\": [\"30518424\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether STON2 regulates DNMT1 directly or indirectly not resolved\",\n        \"Connection between endocytic adaptor activity and epigenetic regulation unexplained\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified STON2 as a direct miRNA target, with miR-199b-5p suppression of STON2 modulating tumor cell growth, migration, invasion, and EMT.\",\n      \"evidence\": \"Dual-luciferase reporter validation of miR-199b-5p binding to STON2 3'UTR, overexpression/knockdown in B-CPAP cells, and xenografts\",\n      \"pmids\": [\"30325582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Downstream effectors of STON2 in thyroid carcinoma not defined\",\n        \"Whether STON2's pro-tumor role uses its endocytic activity unknown\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Positioned STON2 within a competing-endogenous-RNA network as a downstream node of an lncRNA GACAT1/miR-875-3p axis in breast cancer proliferation.\",\n      \"evidence\": \"Dual-luciferase reporter for miR-875-3p/STON2, qRT-PCR, and overexpression rescue in MCF-7 and BCap-37 cells\",\n      \"pmids\": [\"32194758\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"STON2 is a secondary target in the lncRNA study with limited mechanistic dissection\",\n        \"Direct functional role of STON2 in breast cancer not isolated\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Reinforced miRNA regulation of STON2 by showing miR-144-5p directly downregulates STON2 to control thyroid carcinoma proliferation and EMT.\",\n      \"evidence\": \"Dual-luciferase reporter, qRT-PCR, western blot, and overexpression rescue with xenografts\",\n      \"pmids\": [\"35184686\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single lab and mechanistically overlapping with prior miRNA findings\",\n        \"Molecular mechanism downstream of STON2 not distinct from earlier reports\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linked STON2 to lysosomal membrane integrity and Akt-mTOR signaling in oral cancer cells, suggesting a membrane-trafficking role beyond the synapse.\",\n      \"evidence\": \"STON2 overexpression with TFP inhibitor treatment, western blots for Akt-mTOR, and lysosomal integrity and viability assays\",\n      \"pmids\": [\"36702439\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Primarily overexpression plus pharmacological inhibitor without dissection of direct vs. indirect effects\",\n        \"Whether STON2 physically associates with the lysosomal membrane or mTOR machinery untested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How STON2's defined presynaptic endocytic adaptor activity relates mechanistically to its reported roles in cancer epigenetics and lysosomal signaling remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of the STON2-Syt1 interface\",\n        \"Kinase/phosphatase regulating STON2 phosphorylation unidentified\",\n        \"No unifying mechanism connecting synaptic and cancer functions\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"SYT1\",\n      \"SV2A\",\n      \"SV2B\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}