{"gene":"TBC1D16","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2012,"finding":"TBC1D16 is a GTPase-activating protein (GAP) for Rab4A that enhances the intrinsic rate of GTP hydrolysis by Rab4A. TBC1D16 is both cytosolic and membrane-associated; the membrane pool colocalizes with transferrin receptor, EGFR, and EEA1 (early endosome antigen 1), but not with LAMP1. Expression of two TBC1D16 isoforms (but not the catalytically inactive R494A mutant) reduces transferrin receptor recycling without affecting internalization. Overexpression of TBC1D16 alters GFP-Rab4A membrane localization, enhances EGF-stimulated EGFR degradation, and decreases EGFR levels and signaling.","method":"In vitro GTPase activity assay, active-site mutagenesis (R494A), subcellular fractionation/colocalization imaging, transferrin receptor recycling assay, EGFR degradation assay in HeLa cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay plus catalytic mutant plus multiple orthogonal cellular assays (recycling, EGFR degradation, localization) in a single focused study","pmids":["23019362"],"is_preprint":false},{"year":2015,"finding":"A short isoform of TBC1D16 (TBC1D16-47KD), reactivated by promoter hypomethylation, exacerbates melanoma growth and metastasis. Using immunoprecipitation and mass spectrometry, RAB5C was identified as a TBC1D16 target. TBC1D16-47KD regulation of RAB5C controls EGFR levels in melanoma cells.","method":"Immunoprecipitation combined with mass spectrometry to identify RAB5C as substrate; in vitro and in vivo functional assays for melanoma growth and metastasis; DNA methylation analysis","journal":"Nature medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal immunoprecipitation/MS identifying RAB5C plus in vivo tumor assays, single lab, two orthogonal methods","pmids":["26030178"],"is_preprint":false},{"year":2021,"finding":"TBC1D16 inhibits Prototype Foamy Virus (PFV) replication by acting as a GAP for Rab5C. Overexpression of TBC1D16 suppressed PFV Tas and Gag transcription/expression; silencing TBC1D16 enhanced PFV replication. The conserved TBC domain residues R494 and Q531 were essential for this antiviral activity. TBC1D16 also promoted PFV-induced IFN-β production and downstream interferon-stimulated gene transcription.","method":"Overexpression and siRNA knockdown of TBC1D16, active-site mutagenesis (R494 and Q531), viral replication assays, IFN-β reporter assays","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss- and gain-of-function with active-site mutagenesis identifying Rab5C as target, single lab, two orthogonal methods","pmids":["34367131"],"is_preprint":false},{"year":2021,"finding":"TBC1D16 expression in colorectal cancer is driven by a super enhancer. ChIP-Seq-based super enhancer profiling followed by functional validation experiments demonstrated that the super enhancer governing TBC1D16 regulates colorectal cancer tumorigenesis.","method":"H3K27ac ChIP-Seq super enhancer profiling in 73 pairs of colorectal cancer patient tissues; functional validation experiments of TBC1D16 super enhancer activity","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-Seq in large patient cohort plus functional validation, single lab","pmids":["34737287"],"is_preprint":false},{"year":2026,"finding":"Silencing TBC1D16 in HCC cells reduced proliferation, migration, and invasion, and activated NF-κB signaling, indicating that TBC1D16 inhibits NF-κB signaling in HCC. TBC1D16 expression in HCC is transcriptionally regulated by the transcription factor SP1.","method":"siRNA knockdown of TBC1D16, cell functional assays (proliferation, migration, invasion), RNA-seq/KEGG/GSEA pathway analysis, biochemical validation of NF-κB pathway, transcription factor database analysis","journal":"Scandinavian journal of gastroenterology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO/KD with defined cellular phenotype plus pathway validation, single lab, two orthogonal methods","pmids":["41677126"],"is_preprint":false},{"year":2010,"finding":"Computational integration of copy number and expression data identified TBC1D16 and RAB27A as candidate drivers of melanoma proliferation; empirical validation confirmed that melanoma cells are dependent on TBC1D16, suggesting it contributes to abnormal regulation of protein trafficking in melanoma.","method":"Integrative Bayesian framework (copy number + expression), empirical knockdown validation for melanoma cell proliferation dependency","journal":"Cell","confidence":"Low","confidence_rationale":"Tier 3 / Weak — computational prediction plus single empirical dependency validation with limited mechanistic resolution","pmids":["21129771"],"is_preprint":false}],"current_model":"TBC1D16 is a TBC-domain Rab GTPase-activating protein (GAP) that stimulates GTP hydrolysis by Rab4A (and Rab5C), thereby suppressing receptor recycling from early endosomes back to the plasma membrane: membrane-associated TBC1D16 colocalizes with early endosomal markers and EGFR, reduces transferrin receptor recycling, and promotes EGFR degradation and attenuation of EGF signaling; catalytic activity depends on conserved TBC residues R494 and Q531; an epigenetically reactivated short isoform (TBC1D16-47KD) additionally targets RAB5C to modulate EGFR trafficking in melanoma, and TBC1D16 also suppresses NF-κB signaling in hepatocellular carcinoma and acts as an antiviral host factor against Prototype Foamy Virus through its Rab GAP activity."},"narrative":{"mechanistic_narrative":"TBC1D16 is a TBC-domain Rab GTPase-activating protein (GAP) that controls endosomal membrane trafficking by accelerating GTP hydrolysis on Rab4A, thereby restraining recycling of internalized receptors back to the plasma membrane [PMID:23019362]. The protein partitions between cytosol and membranes, with its membrane pool localizing to early endosomes (EEA1-positive) together with transferrin receptor and EGFR; catalytically active TBC1D16 reduces transferrin receptor recycling without affecting its internalization, redistributes Rab4A, and promotes EGF-stimulated EGFR degradation with consequent attenuation of EGFR signaling [PMID:23019362]. GAP activity depends on the conserved catalytic TBC residues R494 and Q531 [PMID:23019362, PMID:34367131]. A short isoform reactivated by promoter hypomethylation (TBC1D16-47KD) additionally engages RAB5C to control EGFR levels and drives melanoma growth and metastasis [PMID:26030178], and TBC1D16 is itself a melanoma proliferation dependency [PMID:21129771]. Beyond endosomal trafficking, TBC1D16 acts as an antiviral host factor that suppresses Prototype Foamy Virus replication and enhances IFN-β responses through its Rab5C GAP activity [PMID:34367131], and it suppresses NF-κB signaling in hepatocellular carcinoma [PMID:41677126]. Its transcription is governed by a super enhancer in colorectal cancer [PMID:34737287] and by the transcription factor SP1 in hepatocellular carcinoma [PMID:41677126].","teleology":[{"year":2010,"claim":"Before any biochemical role was known, an unbiased genomic screen asked which amplified genes drive melanoma proliferation, nominating TBC1D16 as a candidate trafficking regulator.","evidence":"Integrative Bayesian analysis of copy number and expression with empirical knockdown validation in melanoma cells","pmids":["21129771"],"confidence":"Low","gaps":["Computational prediction with limited mechanistic resolution; no molecular activity defined","Did not establish the GAP function or any Rab substrate","Dependency mechanism in melanoma not resolved"]},{"year":2012,"claim":"To define TBC1D16's molecular activity, this work established it as a Rab4A GAP that regulates receptor recycling and EGFR turnover, converting a trafficking 'candidate' into a defined enzyme.","evidence":"In vitro GTPase assay, R494A catalytic mutant, endosomal colocalization imaging, transferrin recycling and EGFR degradation assays in HeLa cells","pmids":["23019362"],"confidence":"High","gaps":["Full Rab substrate spectrum beyond Rab4A not delineated here","Mechanism targeting TBC1D16 to specific endosomal subdomains unknown","No structural model of the catalytic interaction"]},{"year":2015,"claim":"Building on the GAP function, this study asked how TBC1D16 promotes cancer and identified a hypomethylation-reactivated short isoform that targets RAB5C to control EGFR in melanoma.","evidence":"Immunoprecipitation/mass spectrometry to identify RAB5C, DNA methylation analysis, and in vivo melanoma growth/metastasis assays","pmids":["26030178"],"confidence":"Medium","gaps":["Direct in vitro GAP activity toward RAB5C not biochemically reconstituted here","Relationship between Rab4A and RAB5C targeting by different isoforms unclear","Single lab"]},{"year":2021,"claim":"Extending TBC1D16 beyond cancer trafficking, this work showed its Rab5C GAP activity functions as an antiviral effector against Prototype Foamy Virus and boosts interferon responses.","evidence":"Overexpression/siRNA, R494 and Q531 active-site mutants, viral replication assays, IFN-β reporter assays","pmids":["34367131"],"confidence":"Medium","gaps":["Mechanistic link between Rab5C GAP activity and viral transcription suppression not detailed","How TBC1D16 enhances IFN-β production unresolved","Single lab"]},{"year":2021,"claim":"To explain TBC1D16 overexpression in tumors, this study identified a super enhancer driving its transcription in colorectal cancer and tumorigenesis.","evidence":"H3K27ac ChIP-Seq super enhancer profiling across 73 colorectal cancer patient tissue pairs plus functional validation","pmids":["34737287"],"confidence":"Medium","gaps":["Downstream trafficking/GAP consequences in colorectal cancer not linked to phenotype","Transcription factors binding the super enhancer not identified","Single lab"]},{"year":2026,"claim":"This work connected TBC1D16 to a distinct signaling axis, showing it suppresses NF-κB signaling in hepatocellular carcinoma and is transcriptionally driven by SP1.","evidence":"siRNA knockdown with proliferation/migration/invasion assays, RNA-seq pathway analysis, NF-κB validation, transcription factor analysis","pmids":["41677126"],"confidence":"Medium","gaps":["Mechanism linking Rab GAP activity to NF-κB regulation not defined","Direct SP1 binding to the TBC1D16 promoter not biochemically confirmed","Single lab"]},{"year":null,"claim":"It remains unresolved how a single Rab GAP integrates endosomal receptor trafficking with antiviral interferon signaling and NF-κB suppression, and whether these arise from shared or distinct Rab substrates and isoforms.","evidence":"No timeline discovery reconciles the trafficking, antiviral, and signaling roles mechanistically","pmids":[],"confidence":"Low","gaps":["No structural model of TBC1D16 substrate engagement","Functional division of labor between full-length and 47KD isoforms across contexts unclear","Mechanism coupling Rab GAP activity to NF-κB and interferon outputs unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2]}],"complexes":[],"partners":["RAB4A","RAB5C","EGFR"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TBP0","full_name":"TBC1 domain family member 16","aliases":[],"length_aa":767,"mass_kda":86.4,"function":"May act as a GTPase-activating protein for Rab family protein(s)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q8TBP0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TBC1D16","classification":"Not Classified","n_dependent_lines":15,"n_total_lines":1208,"dependency_fraction":0.012417218543046357},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TBC1D16","total_profiled":1310},"omim":[{"mim_id":"616637","title":"TBC1 DOMAIN FAMILY, MEMBER 16; TBC1D16","url":"https://www.omim.org/entry/616637"},{"mim_id":"179511","title":"RAS-ASSOCIATED PROTEIN RAB4A; RAB4A","url":"https://www.omim.org/entry/179511"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Intermediate filaments","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TBC1D16"},"hgnc":{"alias_symbol":["MGC25062","FLJ20748"],"prev_symbol":[]},"alphafold":{"accession":"Q8TBP0","domains":[{"cath_id":"2.30.29.30","chopping":"4-19_33-106_289-378","consensus_level":"high","plddt":71.281,"start":4,"end":378},{"cath_id":"1.10.8.270","chopping":"428-561","consensus_level":"high","plddt":93.9899,"start":428,"end":561},{"cath_id":"1.10.472,1.10.472","chopping":"570-725","consensus_level":"high","plddt":87.2604,"start":570,"end":725}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBP0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBP0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBP0-F1-predicted_aligned_error_v6.png","plddt_mean":68.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TBC1D16","jax_strain_url":"https://www.jax.org/strain/search?query=TBC1D16"},"sequence":{"accession":"Q8TBP0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TBP0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TBP0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBP0"}},"corpus_meta":[{"pmid":"21129771","id":"PMC_21129771","title":"An integrated approach to uncover drivers of cancer.","date":"2010","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/21129771","citation_count":356,"is_preprint":false},{"pmid":"26030178","id":"PMC_26030178","title":"Epigenetic activation of a cryptic TBC1D16 transcript enhances melanoma progression by targeting EGFR.","date":"2015","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26030178","citation_count":99,"is_preprint":false},{"pmid":"34737287","id":"PMC_34737287","title":"Genome-wide profiling in colorectal cancer identifies PHF19 and TBC1D16 as oncogenic super enhancers.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34737287","citation_count":86,"is_preprint":false},{"pmid":"31383000","id":"PMC_31383000","title":"Characterisation of DNA methylation changes in EBF3 and TBC1D16 associated with tumour progression and metastasis in multiple cancer types.","date":"2019","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/31383000","citation_count":39,"is_preprint":false},{"pmid":"23019362","id":"PMC_23019362","title":"TBC1D16 is a Rab4A GTPase activating protein that regulates receptor recycling and EGF receptor signaling.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23019362","citation_count":36,"is_preprint":false},{"pmid":"35592538","id":"PMC_35592538","title":"Identification and Characterization of Extrachromosomal Circular DNA in Plasma of Lung Adenocarcinoma Patients.","date":"2022","source":"International journal of general medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35592538","citation_count":26,"is_preprint":false},{"pmid":"28276657","id":"PMC_28276657","title":"Investigation of correlations between DNA methylation, suicidal behavior and aging.","date":"2017","source":"Bipolar disorders","url":"https://pubmed.ncbi.nlm.nih.gov/28276657","citation_count":25,"is_preprint":false},{"pmid":"34367131","id":"PMC_34367131","title":"Novel Host Protein TBC1D16, a GTPase Activating Protein of Rab5C, Inhibits Prototype Foamy Virus Replication.","date":"2021","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/34367131","citation_count":17,"is_preprint":false},{"pmid":"35437351","id":"PMC_35437351","title":"Construction of a circRNA-Mediated ceRNA Network Reveals Novel Biomarkers for Aortic Dissection.","date":"2022","source":"International journal of general medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35437351","citation_count":16,"is_preprint":false},{"pmid":"35033200","id":"PMC_35033200","title":"Epigenome-wide association study of lung function in Latino children and youth with asthma.","date":"2022","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/35033200","citation_count":16,"is_preprint":false},{"pmid":"25387527","id":"PMC_25387527","title":"Mapping of a blood pressure QTL on chromosome 17 in American Indians of the strong heart family study.","date":"2014","source":"BMC cardiovascular disorders","url":"https://pubmed.ncbi.nlm.nih.gov/25387527","citation_count":5,"is_preprint":false},{"pmid":"39736507","id":"PMC_39736507","title":"Genome-wide analysis in northern Chinese twins identifies twelve new susceptibility loci for pulmonary function.","date":"2024","source":"BMC genomics","url":"https://pubmed.ncbi.nlm.nih.gov/39736507","citation_count":1,"is_preprint":false},{"pmid":"38730308","id":"PMC_38730308","title":"Large-scale transcriptomic and genomic analyses reveal a novel functional gene SERPINB6 for chicken carcass traits.","date":"2024","source":"Journal of animal science and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/38730308","citation_count":1,"is_preprint":false},{"pmid":"41677126","id":"PMC_41677126","title":"The expression pattern and clinical implications of TBC1D16 in hepatocellular carcinoma.","date":"2026","source":"Scandinavian journal of gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/41677126","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.25.25327632","title":"Methylome and transcriptome functional analysis identifies key biomarkers in ketamine’s sustained therapeutic effect on PTSD","date":"2025-05-27","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.25.25327632","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10157,"output_tokens":1819,"usd":0.028878,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8682,"output_tokens":2585,"usd":0.054018,"stage2_stop_reason":"end_turn"},"total_usd":0.082896,"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\": 2012,\n      \"finding\": \"TBC1D16 is a GTPase-activating protein (GAP) for Rab4A that enhances the intrinsic rate of GTP hydrolysis by Rab4A. TBC1D16 is both cytosolic and membrane-associated; the membrane pool colocalizes with transferrin receptor, EGFR, and EEA1 (early endosome antigen 1), but not with LAMP1. Expression of two TBC1D16 isoforms (but not the catalytically inactive R494A mutant) reduces transferrin receptor recycling without affecting internalization. Overexpression of TBC1D16 alters GFP-Rab4A membrane localization, enhances EGF-stimulated EGFR degradation, and decreases EGFR levels and signaling.\",\n      \"method\": \"In vitro GTPase activity assay, active-site mutagenesis (R494A), subcellular fractionation/colocalization imaging, transferrin receptor recycling assay, EGFR degradation assay in HeLa cells\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay plus catalytic mutant plus multiple orthogonal cellular assays (recycling, EGFR degradation, localization) in a single focused study\",\n      \"pmids\": [\"23019362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"A short isoform of TBC1D16 (TBC1D16-47KD), reactivated by promoter hypomethylation, exacerbates melanoma growth and metastasis. Using immunoprecipitation and mass spectrometry, RAB5C was identified as a TBC1D16 target. TBC1D16-47KD regulation of RAB5C controls EGFR levels in melanoma cells.\",\n      \"method\": \"Immunoprecipitation combined with mass spectrometry to identify RAB5C as substrate; in vitro and in vivo functional assays for melanoma growth and metastasis; DNA methylation analysis\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal immunoprecipitation/MS identifying RAB5C plus in vivo tumor assays, single lab, two orthogonal methods\",\n      \"pmids\": [\"26030178\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TBC1D16 inhibits Prototype Foamy Virus (PFV) replication by acting as a GAP for Rab5C. Overexpression of TBC1D16 suppressed PFV Tas and Gag transcription/expression; silencing TBC1D16 enhanced PFV replication. The conserved TBC domain residues R494 and Q531 were essential for this antiviral activity. TBC1D16 also promoted PFV-induced IFN-β production and downstream interferon-stimulated gene transcription.\",\n      \"method\": \"Overexpression and siRNA knockdown of TBC1D16, active-site mutagenesis (R494 and Q531), viral replication assays, IFN-β reporter assays\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss- and gain-of-function with active-site mutagenesis identifying Rab5C as target, single lab, two orthogonal methods\",\n      \"pmids\": [\"34367131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TBC1D16 expression in colorectal cancer is driven by a super enhancer. ChIP-Seq-based super enhancer profiling followed by functional validation experiments demonstrated that the super enhancer governing TBC1D16 regulates colorectal cancer tumorigenesis.\",\n      \"method\": \"H3K27ac ChIP-Seq super enhancer profiling in 73 pairs of colorectal cancer patient tissues; functional validation experiments of TBC1D16 super enhancer activity\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-Seq in large patient cohort plus functional validation, single lab\",\n      \"pmids\": [\"34737287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Silencing TBC1D16 in HCC cells reduced proliferation, migration, and invasion, and activated NF-κB signaling, indicating that TBC1D16 inhibits NF-κB signaling in HCC. TBC1D16 expression in HCC is transcriptionally regulated by the transcription factor SP1.\",\n      \"method\": \"siRNA knockdown of TBC1D16, cell functional assays (proliferation, migration, invasion), RNA-seq/KEGG/GSEA pathway analysis, biochemical validation of NF-κB pathway, transcription factor database analysis\",\n      \"journal\": \"Scandinavian journal of gastroenterology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO/KD with defined cellular phenotype plus pathway validation, single lab, two orthogonal methods\",\n      \"pmids\": [\"41677126\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Computational integration of copy number and expression data identified TBC1D16 and RAB27A as candidate drivers of melanoma proliferation; empirical validation confirmed that melanoma cells are dependent on TBC1D16, suggesting it contributes to abnormal regulation of protein trafficking in melanoma.\",\n      \"method\": \"Integrative Bayesian framework (copy number + expression), empirical knockdown validation for melanoma cell proliferation dependency\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — computational prediction plus single empirical dependency validation with limited mechanistic resolution\",\n      \"pmids\": [\"21129771\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TBC1D16 is a TBC-domain Rab GTPase-activating protein (GAP) that stimulates GTP hydrolysis by Rab4A (and Rab5C), thereby suppressing receptor recycling from early endosomes back to the plasma membrane: membrane-associated TBC1D16 colocalizes with early endosomal markers and EGFR, reduces transferrin receptor recycling, and promotes EGFR degradation and attenuation of EGF signaling; catalytic activity depends on conserved TBC residues R494 and Q531; an epigenetically reactivated short isoform (TBC1D16-47KD) additionally targets RAB5C to modulate EGFR trafficking in melanoma, and TBC1D16 also suppresses NF-κB signaling in hepatocellular carcinoma and acts as an antiviral host factor against Prototype Foamy Virus through its Rab GAP activity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TBC1D16 is a TBC-domain Rab GTPase-activating protein (GAP) that controls endosomal membrane trafficking by accelerating GTP hydrolysis on Rab4A, thereby restraining recycling of internalized receptors back to the plasma membrane [#0]. The protein partitions between cytosol and membranes, with its membrane pool localizing to early endosomes (EEA1-positive) together with transferrin receptor and EGFR; catalytically active TBC1D16 reduces transferrin receptor recycling without affecting its internalization, redistributes Rab4A, and promotes EGF-stimulated EGFR degradation with consequent attenuation of EGFR signaling [#0]. GAP activity depends on the conserved catalytic TBC residues R494 and Q531 [#0, #2]. A short isoform reactivated by promoter hypomethylation (TBC1D16-47KD) additionally engages RAB5C to control EGFR levels and drives melanoma growth and metastasis [#1], and TBC1D16 is itself a melanoma proliferation dependency [#5]. Beyond endosomal trafficking, TBC1D16 acts as an antiviral host factor that suppresses Prototype Foamy Virus replication and enhances IFN-\\u03b2 responses through its Rab5C GAP activity [#2], and it suppresses NF-\\u03baB signaling in hepatocellular carcinoma [#4]. Its transcription is governed by a super enhancer in colorectal cancer [#3] and by the transcription factor SP1 in hepatocellular carcinoma [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Before any biochemical role was known, an unbiased genomic screen asked which amplified genes drive melanoma proliferation, nominating TBC1D16 as a candidate trafficking regulator.\",\n      \"evidence\": \"Integrative Bayesian analysis of copy number and expression with empirical knockdown validation in melanoma cells\",\n      \"pmids\": [\"21129771\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational prediction with limited mechanistic resolution; no molecular activity defined\", \"Did not establish the GAP function or any Rab substrate\", \"Dependency mechanism in melanoma not resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"To define TBC1D16's molecular activity, this work established it as a Rab4A GAP that regulates receptor recycling and EGFR turnover, converting a trafficking 'candidate' into a defined enzyme.\",\n      \"evidence\": \"In vitro GTPase assay, R494A catalytic mutant, endosomal colocalization imaging, transferrin recycling and EGFR degradation assays in HeLa cells\",\n      \"pmids\": [\"23019362\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full Rab substrate spectrum beyond Rab4A not delineated here\", \"Mechanism targeting TBC1D16 to specific endosomal subdomains unknown\", \"No structural model of the catalytic interaction\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Building on the GAP function, this study asked how TBC1D16 promotes cancer and identified a hypomethylation-reactivated short isoform that targets RAB5C to control EGFR in melanoma.\",\n      \"evidence\": \"Immunoprecipitation/mass spectrometry to identify RAB5C, DNA methylation analysis, and in vivo melanoma growth/metastasis assays\",\n      \"pmids\": [\"26030178\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct in vitro GAP activity toward RAB5C not biochemically reconstituted here\", \"Relationship between Rab4A and RAB5C targeting by different isoforms unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extending TBC1D16 beyond cancer trafficking, this work showed its Rab5C GAP activity functions as an antiviral effector against Prototype Foamy Virus and boosts interferon responses.\",\n      \"evidence\": \"Overexpression/siRNA, R494 and Q531 active-site mutants, viral replication assays, IFN-\\u03b2 reporter assays\",\n      \"pmids\": [\"34367131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between Rab5C GAP activity and viral transcription suppression not detailed\", \"How TBC1D16 enhances IFN-\\u03b2 production unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"To explain TBC1D16 overexpression in tumors, this study identified a super enhancer driving its transcription in colorectal cancer and tumorigenesis.\",\n      \"evidence\": \"H3K27ac ChIP-Seq super enhancer profiling across 73 colorectal cancer patient tissue pairs plus functional validation\",\n      \"pmids\": [\"34737287\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream trafficking/GAP consequences in colorectal cancer not linked to phenotype\", \"Transcription factors binding the super enhancer not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"This work connected TBC1D16 to a distinct signaling axis, showing it suppresses NF-\\u03baB signaling in hepatocellular carcinoma and is transcriptionally driven by SP1.\",\n      \"evidence\": \"siRNA knockdown with proliferation/migration/invasion assays, RNA-seq pathway analysis, NF-\\u03baB validation, transcription factor analysis\",\n      \"pmids\": [\"41677126\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking Rab GAP activity to NF-\\u03baB regulation not defined\", \"Direct SP1 binding to the TBC1D16 promoter not biochemically confirmed\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how a single Rab GAP integrates endosomal receptor trafficking with antiviral interferon signaling and NF-\\u03baB suppression, and whether these arise from shared or distinct Rab substrates and isoforms.\",\n      \"evidence\": \"No timeline discovery reconciles the trafficking, antiviral, and signaling roles mechanistically\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of TBC1D16 substrate engagement\", \"Functional division of labor between full-length and 47KD isoforms across contexts unclear\", \"Mechanism coupling Rab GAP activity to NF-\\u03baB and interferon outputs unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RAB4A\", \"RAB5C\", \"EGFR\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}