{"gene":"SYTL2","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2013,"finding":"Slp2-a (SYTL2) controls renal epithelial cell size through a Rab27-independent mechanism: its C2B domain recruits Rap1 GAPs to the plasma membrane of MDCK II cells, thereby inactivating Rap signaling. Functional ablation of Slp2-a increased cell size, and blockade of ezrin (a downstream Rap target) with miglustat inhibited cell spreading in Slp2-a-knockdown cells.","method":"siRNA knockdown, domain mutagenesis, pharmacological inhibition (miglustat), epistasis with Drosophila Bitesize ortholog rescue, fractionation/localization assays in MDCK II cells","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal domain mapping, genetic rescue with Drosophila ortholog, pharmacological epistasis, and multiple orthogonal methods in a single focused study","pmids":["24284068"],"is_preprint":false},{"year":2013,"finding":"Slp2-a (SYTL2) aberrant expression was detected in pcy (Nphp3-pcy) mice, a polycystic kidney disease model, together with increased ezrin activity, consistent with its role in controlling renal cell size via the Rap-ezrin axis.","method":"Protein expression analysis and ezrin activity assay in pcy mouse kidney tissue","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — correlative tissue data in a disease model, but mechanistic link supported by the same paper's functional experiments","pmids":["24284068"],"is_preprint":false},{"year":2008,"finding":"In dysferlin-deficient (LGMD2B) muscle, Rab27A and Slp2a/SYTL2 are co-induced and proposed to form a compensatory vesicular trafficking pathway for membrane repair. The same pathway may release endocytotic vesicle contents, contributing to inflammatory onset.","method":"mRNA expression profiling of patient muscle biopsies compared with disease controls and normals; pathway analysis","journal":"The American journal of pathology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — expression profiling only; no direct functional reconstitution of the SYTL2-Rab27A complex in this context","pmids":["18832576"],"is_preprint":false},{"year":2023,"finding":"SYTL2 promotes prostate cancer cell migration, invasion, pseudopodia formation, and lymph node metastasis by binding to fascin actin-bundling protein 1 (FSCN1) and inhibiting its proteasome-mediated degradation, thereby stabilizing FSCN1 protein levels. Targeting FSCN1 rescued and reversed the oncogenic effect of SYTL2.","method":"Co-immunoprecipitation, protein stability assay, migration/invasion assays, 3D migration model, popliteal lymph node metastasis mouse model, rescue experiments with FSCN1 knockdown/inhibition","journal":"Journal of translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, protein stability assays, in vitro and in vivo functional models, rescue experiments; single lab but multiple orthogonal methods","pmids":["37147713"],"is_preprint":false},{"year":2023,"finding":"In alveolar soft part sarcoma (ASPS), Rab27a and Sytl2 together facilitate trafficking of cytoplasmic vesicles containing angiogenic factors (Pdgfb and Vwf) to promote pericyte-rich vascular network construction. ASPSCR1::TFE3 drives Sytl2 expression via super-enhancer activity, and loss of ASPSCR1::TFE3 reduces Sytl2 enhancer activity and impairs angiogenesis in vivo.","method":"Epigenomic CRISPR/dCas9 screening, super-enhancer mapping, in vivo tumor model, vesicle trafficking functional assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR epigenomic screen and in vivo model; trafficking function inferred from Rab27a/Sytl2 co-upregulation and angiogenic factor levels, single lab","pmids":["37029109"],"is_preprint":false},{"year":2016,"finding":"Overexpression of SYTL2 in ovarian carcinoma cells (SK-OV-3) promoted cell migration and invasiveness. SYTL2 expression in metastatic xenograft implants was regulated by DNA methylation at specific CpG sites in its promoter, and demethylating agents and HDAC inhibitors induced SYTL2 upregulation.","method":"Gene overexpression, migration and invasion assays, bisulfite sequencing of CpG methylation, pharmacological demethylation (5-aza-2'-deoxycytidine) and HDAC inhibition (TSA), xenograft mouse model","journal":"Oncology reports","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional migration/invasion assays with overexpression and methylation mechanistic follow-up; single lab, multiple orthogonal methods but no domain-level mechanistic dissection","pmids":["27220283"],"is_preprint":false}],"current_model":"SYTL2 (Slp2-a) is a Rab27 effector protein whose C2A domain binds Rab27-bearing vesicles for organelle transport and whose C2B domain independently recruits Rap1 GAPs to the plasma membrane to inactivate Rap-ezrin signaling and control epithelial cell size; in cancer contexts, SYTL2 promotes cell migration, invasion, and metastasis by stabilizing the actin-bundling protein FSCN1 against proteasomal degradation (driving pseudopodia formation in prostate cancer) and, together with Rab27a, facilitates trafficking of angiogenic factor-containing vesicles (Pdgfb, Vwf) to support tumor vascularization in alveolar soft part sarcoma."},"narrative":{"mechanistic_narrative":"SYTL2 (Slp2-a) is a membrane- and vesicle-associated effector that couples Rab27-dependent vesicular trafficking to actin- and Rap-based control of cell shape, spreading, and motility [PMID:24284068, PMID:37029109]. Its two C2 domains act through separable mechanisms: the C2B domain recruits Rap1 GAPs to the plasma membrane of renal epithelial cells to inactivate Rap signaling and its downstream effector ezrin, thereby restraining cell spreading and controlling epithelial cell size in a Rab27-independent manner [PMID:24284068]. In cancer settings SYTL2 acts as a pro-migratory and pro-metastatic factor: in prostate cancer it binds the actin-bundling protein FSCN1 and protects it from proteasomal degradation, stabilizing FSCN1 to drive pseudopodia formation, migration, invasion, and lymph node metastasis [PMID:37147713]. Together with Rab27a it facilitates trafficking of vesicles carrying angiogenic factors (Pdgfb, Vwf) to support tumor vascularization in alveolar soft part sarcoma, where it is driven as a super-enhancer target of the ASPSCR1::TFE3 fusion [PMID:37029109]. SYTL2 expression is itself epigenetically regulated, with promoter CpG methylation governing its levels in ovarian carcinoma [PMID:27220283].","teleology":[{"year":2008,"claim":"Established a candidate compensatory trafficking role for SYTL2 by linking it with Rab27A in a disease context where the question was how membrane repair pathways adapt to dysferlin loss.","evidence":"mRNA expression profiling of dysferlin-deficient (LGMD2B) patient muscle biopsies with pathway analysis","pmids":["18832576"],"confidence":"Low","gaps":["Correlative expression only, no direct functional reconstitution of a SYTL2-Rab27A complex in muscle repair","Did not demonstrate vesicular trafficking activity for SYTL2 directly","Causal contribution to inflammation not tested"]},{"year":2013,"claim":"Resolved how SYTL2 controls epithelial cell size, showing a Rab27-independent C2B-domain mechanism that recruits Rap1 GAPs to inactivate Rap-ezrin signaling and restrain cell spreading.","evidence":"siRNA knockdown, domain mutagenesis, pharmacological epistasis (miglustat), Drosophila ortholog rescue, and fractionation in MDCK II cells; with correlative ezrin-activity data in the pcy polycystic kidney model","pmids":["24284068"],"confidence":"High","gaps":["Identity of the specific Rap1 GAP(s) recruited not fully defined","Mechanism of C2B-domain membrane targeting not structurally resolved","Disease model link to polycystic kidney disease is correlative"]},{"year":2016,"claim":"Showed SYTL2 is a migration/invasion-promoting factor whose expression is set epigenetically, addressing how its oncogenic levels are controlled.","evidence":"Overexpression with migration/invasion assays, bisulfite sequencing of promoter CpGs, pharmacological demethylation and HDAC inhibition, and xenograft model in ovarian carcinoma cells","pmids":["27220283"],"confidence":"Medium","gaps":["Molecular effector through which SYTL2 drives migration not identified in this context","No domain-level mechanistic dissection","Single cell-line system"]},{"year":2023,"claim":"Defined a molecular mechanism for SYTL2-driven metastasis: it binds and stabilizes FSCN1 against proteasomal degradation to promote pseudopodia and invasion.","evidence":"Reciprocal Co-IP, protein stability assays, 3D migration and invasion assays, popliteal lymph node metastasis mouse model, and FSCN1 rescue experiments in prostate cancer","pmids":["37147713"],"confidence":"High","gaps":["Mechanism by which SYTL2 binding blocks FSCN1 ubiquitination/degradation not defined","Domain of SYTL2 mediating FSCN1 binding not mapped","Whether Rab27 binding contributes to this function unknown"]},{"year":2023,"claim":"Connected SYTL2 to tumor angiogenesis, showing it works with Rab27a to traffic angiogenic-factor vesicles and is itself a super-enhancer target of the ASPSCR1::TFE3 fusion.","evidence":"Epigenomic CRISPR/dCas9 screening, super-enhancer mapping, vesicle trafficking assays, and in vivo tumor model in alveolar soft part sarcoma","pmids":["37029109"],"confidence":"Medium","gaps":["Trafficking role inferred from co-upregulation and angiogenic factor levels rather than direct vesicle-tracking of SYTL2","Direct cargo selectivity for Pdgfb/Vwf vesicles not established","Single lab and tumor type"]},{"year":null,"claim":"How SYTL2's distinct C2A/Rab27-dependent trafficking activity and C2B/Rap-GAP and FSCN1-stabilizing activities are integrated or switched between epithelial homeostasis and cancer remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No unified model linking the Rab27-binding and FSCN1-stabilizing functions","Structural basis of C2-domain partner selection not determined","Physiological (non-cancer) role of the FSCN1 interaction untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[4]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[3,4,5]}],"complexes":[],"partners":["RAB27A","FSCN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9HCH5","full_name":"Synaptotagmin-like protein 2","aliases":["Breast cancer-associated antigen SGA-72M","Exophilin-4"],"length_aa":934,"mass_kda":104.9,"function":"Isoform 1 acts as a RAB27A effector protein and plays a role in cytotoxic granule exocytosis in lymphocytes. It is required for cytotoxic granule docking at the immunologic synapse. Isoform 4 binds phosphatidylserine (PS) and phosphatidylinositol-4,5-bisphosphate (PIP2) and promotes the recruitment of glucagon-containing granules to the cell membrane in pancreatic alpha cells. Binding to PS is inhibited by Ca(2+) while binding to PIP2 is Ca(2+) insensitive","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9HCH5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SYTL2","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/SYTL2","total_profiled":1310},"omim":[{"mim_id":"612880","title":"SYNAPTOTAGMIN-LIKE 2; SYTL2","url":"https://www.omim.org/entry/612880"},{"mim_id":"612878","title":"EXOPHILIN 5; EXPH5","url":"https://www.omim.org/entry/612878"},{"mim_id":"603868","title":"RAS-ASSOCIATED PROTEIN RAB27A; RAB27A","url":"https://www.omim.org/entry/603868"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"intestine","ntpm":68.5},{"tissue":"stomach 1","ntpm":118.9}],"url":"https://www.proteinatlas.org/search/SYTL2"},"hgnc":{"alias_symbol":["FLJ20163","FLJ21219","KIAA1597","exophilin-4","CHR11SYT","SLP2","SGA72M","MGC102768","PPP1R151"],"prev_symbol":[]},"alphafold":{"accession":"Q9HCH5","domains":[{"cath_id":"-","chopping":"10-77","consensus_level":"high","plddt":85.7634,"start":10,"end":77},{"cath_id":"2.60.40.150","chopping":"625-755","consensus_level":"high","plddt":88.7755,"start":625,"end":755},{"cath_id":"2.60.40.150","chopping":"772-924","consensus_level":"high","plddt":88.5125,"start":772,"end":924}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HCH5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HCH5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HCH5-F1-predicted_aligned_error_v6.png","plddt_mean":57.72},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SYTL2","jax_strain_url":"https://www.jax.org/strain/search?query=SYTL2"},"sequence":{"accession":"Q9HCH5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9HCH5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9HCH5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HCH5"}},"corpus_meta":[{"pmid":"22724020","id":"PMC_22724020","title":"Deregulation of Rab and Rab effector genes in bladder cancer.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22724020","citation_count":100,"is_preprint":false},{"pmid":"15501219","id":"PMC_15501219","title":"Muscle satellite cell-specific genes identified by genetic profiling of MyoD-deficient myogenic cell.","date":"2004","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/15501219","citation_count":68,"is_preprint":false},{"pmid":"35487942","id":"PMC_35487942","title":"Comprehensive profiling of 1015 patients' exomes reveals genomic-clinical associations in colorectal cancer.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35487942","citation_count":62,"is_preprint":false},{"pmid":"18832576","id":"PMC_18832576","title":"Dysferlin deficiency shows compensatory induction of Rab27A/Slp2a that may contribute to inflammatory onset.","date":"2008","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/18832576","citation_count":42,"is_preprint":false},{"pmid":"37029109","id":"PMC_37029109","title":"ASPSCR1::TFE3 orchestrates the angiogenic program of alveolar soft part sarcoma.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37029109","citation_count":27,"is_preprint":false},{"pmid":"33539530","id":"PMC_33539530","title":"Diseasome and comorbidities complexities of SARS-CoV-2 infection with common malignant diseases.","date":"2021","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/33539530","citation_count":26,"is_preprint":false},{"pmid":"30760317","id":"PMC_30760317","title":"Dermal mesenchymal stem cells: a resource of migration-associated function in psoriasis?","date":"2019","source":"Stem cell research & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/30760317","citation_count":23,"is_preprint":false},{"pmid":"27220283","id":"PMC_27220283","title":"Synaptotagmin-like protein 2 gene promotes the metastatic potential in ovarian cancer.","date":"2016","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/27220283","citation_count":15,"is_preprint":false},{"pmid":"23660444","id":"PMC_23660444","title":"Cortisol treatment of prespawning female cod affects cytogenesis related factors in eggs and embryos.","date":"2013","source":"General and comparative endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/23660444","citation_count":15,"is_preprint":false},{"pmid":"32351327","id":"PMC_32351327","title":"Long noncoding RNA BSN-AS2 induced by E2F1 promotes spinal osteosarcoma progression by targeting miR-654-3p/SYTL2 axis.","date":"2020","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/32351327","citation_count":13,"is_preprint":false},{"pmid":"37147713","id":"PMC_37147713","title":"SYTL2 promotes metastasis of prostate cancer cells by enhancing FSCN1-mediated pseudopodia formation and invasion.","date":"2023","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37147713","citation_count":12,"is_preprint":false},{"pmid":"30157785","id":"PMC_30157785","title":"Daphnane diterpenes inhibit the metastatic potential of B16F10 murine melanoma cells in vitro and in vivo.","date":"2018","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/30157785","citation_count":11,"is_preprint":false},{"pmid":"24284068","id":"PMC_24284068","title":"Slp2-a controls renal epithelial cell size through regulation of Rap-ezrin signaling independently of Rab27.","date":"2013","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/24284068","citation_count":9,"is_preprint":false},{"pmid":"33378017","id":"PMC_33378017","title":"Molecular insights into the development of hepatic metastases in colorectal cancer: a metastasis prediction study.","date":"2020","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33378017","citation_count":9,"is_preprint":false},{"pmid":"39955494","id":"PMC_39955494","title":"Hippocampal gray matter volume alterations in patients with first-episode and recurrent major depressive disorder and their associations with gene profiles.","date":"2025","source":"BMC psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/39955494","citation_count":8,"is_preprint":false},{"pmid":"37640670","id":"PMC_37640670","title":"Effects of COL1A1 and SYTL2 on inflammatory cell infiltration and poor extracellular matrix remodeling of the vascular wall in thoracic aortic aneurysm.","date":"2023","source":"Chinese medical journal","url":"https://pubmed.ncbi.nlm.nih.gov/37640670","citation_count":6,"is_preprint":false},{"pmid":"35369343","id":"PMC_35369343","title":"Identification of Potential Diagnostic Biomarkers From Circulating Cells During the Course of Sleep Deprivation-Related Myocardial Infarction Based on Bioinformatics Analyses.","date":"2022","source":"Frontiers in cardiovascular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35369343","citation_count":6,"is_preprint":false},{"pmid":"36232302","id":"PMC_36232302","title":"mRNA Capture Sequencing and RT-qPCR for the Detection of Pathognomonic, Novel, and Secondary Fusion Transcripts in FFPE Tissue: A Sarcoma Showcase.","date":"2022","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36232302","citation_count":6,"is_preprint":false},{"pmid":"30391830","id":"PMC_30391830","title":"In-depth characterization of the pituitary transcriptome in Simmental and Chinese native cattle.","date":"2018","source":"Domestic animal endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/30391830","citation_count":6,"is_preprint":false},{"pmid":"38162650","id":"PMC_38162650","title":"Lineage tracing of T cell differentiation from T-iPSC by 2D feeder-free culture and 3D organoid culture.","date":"2023","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/38162650","citation_count":5,"is_preprint":false},{"pmid":"29159500","id":"PMC_29159500","title":"Comparative analysis of molecular activity in dermal mesenchymal stem cells from different passages.","date":"2017","source":"Cell and tissue banking","url":"https://pubmed.ncbi.nlm.nih.gov/29159500","citation_count":4,"is_preprint":false},{"pmid":"33936709","id":"PMC_33936709","title":"Transition to lanadelumab-flyo from three medications for a hereditary angioedema patient with a variant in the SYTL2 gene: A case report.","date":"2021","source":"Clinical case reports","url":"https://pubmed.ncbi.nlm.nih.gov/33936709","citation_count":1,"is_preprint":false},{"pmid":"39009511","id":"PMC_39009511","title":"[Alveolar Soft Part Sarcoma-The Angiogenic Mechanism Regulated by a Fusion Gene Product].","date":"2024","source":"Gan to kagaku ryoho. Cancer & chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/39009511","citation_count":1,"is_preprint":false},{"pmid":"42181237","id":"PMC_42181237","title":"SYTL2 and DENND2B as shared drivers in mouse abdominal aortic aneurysm and lung cancer.","date":"2026","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/42181237","citation_count":0,"is_preprint":false},{"pmid":"39676131","id":"PMC_39676131","title":"Identification of diagnostic biomarkers in prostate cancer-related fatigue by construction of predictive models and experimental validation.","date":"2024","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/39676131","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14921,"output_tokens":1728,"usd":0.035341,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8531,"output_tokens":2396,"usd":0.051277,"stage2_stop_reason":"end_turn"},"total_usd":0.086618,"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\": \"Slp2-a (SYTL2) controls renal epithelial cell size through a Rab27-independent mechanism: its C2B domain recruits Rap1 GAPs to the plasma membrane of MDCK II cells, thereby inactivating Rap signaling. Functional ablation of Slp2-a increased cell size, and blockade of ezrin (a downstream Rap target) with miglustat inhibited cell spreading in Slp2-a-knockdown cells.\",\n      \"method\": \"siRNA knockdown, domain mutagenesis, pharmacological inhibition (miglustat), epistasis with Drosophila Bitesize ortholog rescue, fractionation/localization assays in MDCK II cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal domain mapping, genetic rescue with Drosophila ortholog, pharmacological epistasis, and multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"24284068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Slp2-a (SYTL2) aberrant expression was detected in pcy (Nphp3-pcy) mice, a polycystic kidney disease model, together with increased ezrin activity, consistent with its role in controlling renal cell size via the Rap-ezrin axis.\",\n      \"method\": \"Protein expression analysis and ezrin activity assay in pcy mouse kidney tissue\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — correlative tissue data in a disease model, but mechanistic link supported by the same paper's functional experiments\",\n      \"pmids\": [\"24284068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In dysferlin-deficient (LGMD2B) muscle, Rab27A and Slp2a/SYTL2 are co-induced and proposed to form a compensatory vesicular trafficking pathway for membrane repair. The same pathway may release endocytotic vesicle contents, contributing to inflammatory onset.\",\n      \"method\": \"mRNA expression profiling of patient muscle biopsies compared with disease controls and normals; pathway analysis\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — expression profiling only; no direct functional reconstitution of the SYTL2-Rab27A complex in this context\",\n      \"pmids\": [\"18832576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SYTL2 promotes prostate cancer cell migration, invasion, pseudopodia formation, and lymph node metastasis by binding to fascin actin-bundling protein 1 (FSCN1) and inhibiting its proteasome-mediated degradation, thereby stabilizing FSCN1 protein levels. Targeting FSCN1 rescued and reversed the oncogenic effect of SYTL2.\",\n      \"method\": \"Co-immunoprecipitation, protein stability assay, migration/invasion assays, 3D migration model, popliteal lymph node metastasis mouse model, rescue experiments with FSCN1 knockdown/inhibition\",\n      \"journal\": \"Journal of translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, protein stability assays, in vitro and in vivo functional models, rescue experiments; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"37147713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In alveolar soft part sarcoma (ASPS), Rab27a and Sytl2 together facilitate trafficking of cytoplasmic vesicles containing angiogenic factors (Pdgfb and Vwf) to promote pericyte-rich vascular network construction. ASPSCR1::TFE3 drives Sytl2 expression via super-enhancer activity, and loss of ASPSCR1::TFE3 reduces Sytl2 enhancer activity and impairs angiogenesis in vivo.\",\n      \"method\": \"Epigenomic CRISPR/dCas9 screening, super-enhancer mapping, in vivo tumor model, vesicle trafficking functional assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR epigenomic screen and in vivo model; trafficking function inferred from Rab27a/Sytl2 co-upregulation and angiogenic factor levels, single lab\",\n      \"pmids\": [\"37029109\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Overexpression of SYTL2 in ovarian carcinoma cells (SK-OV-3) promoted cell migration and invasiveness. SYTL2 expression in metastatic xenograft implants was regulated by DNA methylation at specific CpG sites in its promoter, and demethylating agents and HDAC inhibitors induced SYTL2 upregulation.\",\n      \"method\": \"Gene overexpression, migration and invasion assays, bisulfite sequencing of CpG methylation, pharmacological demethylation (5-aza-2'-deoxycytidine) and HDAC inhibition (TSA), xenograft mouse model\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional migration/invasion assays with overexpression and methylation mechanistic follow-up; single lab, multiple orthogonal methods but no domain-level mechanistic dissection\",\n      \"pmids\": [\"27220283\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SYTL2 (Slp2-a) is a Rab27 effector protein whose C2A domain binds Rab27-bearing vesicles for organelle transport and whose C2B domain independently recruits Rap1 GAPs to the plasma membrane to inactivate Rap-ezrin signaling and control epithelial cell size; in cancer contexts, SYTL2 promotes cell migration, invasion, and metastasis by stabilizing the actin-bundling protein FSCN1 against proteasomal degradation (driving pseudopodia formation in prostate cancer) and, together with Rab27a, facilitates trafficking of angiogenic factor-containing vesicles (Pdgfb, Vwf) to support tumor vascularization in alveolar soft part sarcoma.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SYTL2 (Slp2-a) is a membrane- and vesicle-associated effector that couples Rab27-dependent vesicular trafficking to actin- and Rap-based control of cell shape, spreading, and motility [#0, #4]. Its two C2 domains act through separable mechanisms: the C2B domain recruits Rap1 GAPs to the plasma membrane of renal epithelial cells to inactivate Rap signaling and its downstream effector ezrin, thereby restraining cell spreading and controlling epithelial cell size in a Rab27-independent manner [#0]. In cancer settings SYTL2 acts as a pro-migratory and pro-metastatic factor: in prostate cancer it binds the actin-bundling protein FSCN1 and protects it from proteasomal degradation, stabilizing FSCN1 to drive pseudopodia formation, migration, invasion, and lymph node metastasis [#3]. Together with Rab27a it facilitates trafficking of vesicles carrying angiogenic factors (Pdgfb, Vwf) to support tumor vascularization in alveolar soft part sarcoma, where it is driven as a super-enhancer target of the ASPSCR1::TFE3 fusion [#4]. SYTL2 expression is itself epigenetically regulated, with promoter CpG methylation governing its levels in ovarian carcinoma [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established a candidate compensatory trafficking role for SYTL2 by linking it with Rab27A in a disease context where the question was how membrane repair pathways adapt to dysferlin loss.\",\n      \"evidence\": \"mRNA expression profiling of dysferlin-deficient (LGMD2B) patient muscle biopsies with pathway analysis\",\n      \"pmids\": [\"18832576\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Correlative expression only, no direct functional reconstitution of a SYTL2-Rab27A complex in muscle repair\", \"Did not demonstrate vesicular trafficking activity for SYTL2 directly\", \"Causal contribution to inflammation not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Resolved how SYTL2 controls epithelial cell size, showing a Rab27-independent C2B-domain mechanism that recruits Rap1 GAPs to inactivate Rap-ezrin signaling and restrain cell spreading.\",\n      \"evidence\": \"siRNA knockdown, domain mutagenesis, pharmacological epistasis (miglustat), Drosophila ortholog rescue, and fractionation in MDCK II cells; with correlative ezrin-activity data in the pcy polycystic kidney model\",\n      \"pmids\": [\"24284068\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the specific Rap1 GAP(s) recruited not fully defined\", \"Mechanism of C2B-domain membrane targeting not structurally resolved\", \"Disease model link to polycystic kidney disease is correlative\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed SYTL2 is a migration/invasion-promoting factor whose expression is set epigenetically, addressing how its oncogenic levels are controlled.\",\n      \"evidence\": \"Overexpression with migration/invasion assays, bisulfite sequencing of promoter CpGs, pharmacological demethylation and HDAC inhibition, and xenograft model in ovarian carcinoma cells\",\n      \"pmids\": [\"27220283\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular effector through which SYTL2 drives migration not identified in this context\", \"No domain-level mechanistic dissection\", \"Single cell-line system\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a molecular mechanism for SYTL2-driven metastasis: it binds and stabilizes FSCN1 against proteasomal degradation to promote pseudopodia and invasion.\",\n      \"evidence\": \"Reciprocal Co-IP, protein stability assays, 3D migration and invasion assays, popliteal lymph node metastasis mouse model, and FSCN1 rescue experiments in prostate cancer\",\n      \"pmids\": [\"37147713\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which SYTL2 binding blocks FSCN1 ubiquitination/degradation not defined\", \"Domain of SYTL2 mediating FSCN1 binding not mapped\", \"Whether Rab27 binding contributes to this function unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Connected SYTL2 to tumor angiogenesis, showing it works with Rab27a to traffic angiogenic-factor vesicles and is itself a super-enhancer target of the ASPSCR1::TFE3 fusion.\",\n      \"evidence\": \"Epigenomic CRISPR/dCas9 screening, super-enhancer mapping, vesicle trafficking assays, and in vivo tumor model in alveolar soft part sarcoma\",\n      \"pmids\": [\"37029109\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Trafficking role inferred from co-upregulation and angiogenic factor levels rather than direct vesicle-tracking of SYTL2\", \"Direct cargo selectivity for Pdgfb/Vwf vesicles not established\", \"Single lab and tumor type\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SYTL2's distinct C2A/Rab27-dependent trafficking activity and C2B/Rap-GAP and FSCN1-stabilizing activities are integrated or switched between epithelial homeostasis and cancer remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unified model linking the Rab27-binding and FSCN1-stabilizing functions\", \"Structural basis of C2-domain partner selection not determined\", \"Physiological (non-cancer) role of the FSCN1 interaction untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [3, 4, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RAB27A\", \"FSCN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":5,"faith_total":5,"faith_pct":100.0}}